DRESSING FOR ALTITUDE U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle
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Since its earliest days, flight has been about ...

Since its earliest days, flight has been about
pushing the limits of technology and, in many
cases, pushing the limits of human endurance.
The human body can be the limiting factor in
the design of aircraft and spacecraft. Humans
cannot survive unaided at high altitudes.
There have been a number of books written
on the subject of spacesuits, but the literature
on the high-altitude pressure suits is lacking.
This volume provides a high-level summary
of the technological development and operational
use of partial- and full-pressure suits,
from the earliest models to the current highaltitude,
full-pressure suits used for modern
aviation, as well as those that were used for
launch and entry on the Space Shuttle. The
goal of this work is to provide a resource on
the technology for suits designed to keep
humans alive at the edge of space. Hopefully,
future generations will learn from the hardfought
lessons of the past.
NASA is committed to the future of
aerospace, and a key component of that
future is the workforce. Without these men
and women, technological advancements
would not be possible. Dressing for Altitude
is designed to provide the history of the
technology and to explore the lessons learned
through years of research in creating, testing,
and utilizing today’s high-altitude suits. It
is our hope that this information will prove
helpful in the development of future suits.
Even with the closeout of the Space Shuttle
and the planned ending of the U-2 program,
pressure suits will be needed for protection as
long as humans seek to explore high frontiers.
The NASA Aeronautics Research Mission
Directorate is committed to the training of
the current and future aerospace workforce.
This book and the other books published
by the NASA Aeronautics Research Mission
Directorate are in support of this commitment.
Hopefully, you will find this book a
valuable resource for many years to come.
Tony Springer
Lead, Communications and Education
NASA Aeronautics Research Mission Directorate

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    DRESSING FOR ALTITUDE U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle DRESSING FOR ALTITUDE U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle Presentation Transcript

    • Dressingfor AltitudeU.S. Aviation Pressure Suits–Wiley Post to Space ShuttleDennis R. Jenkins
    • DRESSING FOR ALTITUDEU.S. Aviation Pressure Suits—Wiley Post to Space Shuttle
    • Copyright © 2012 by the National Aeronautics and Space Administration The opinions expressed in this volume are those of the authors and do notnecessarily reflect the official positions of the United States Government or of the National Aeronautics and Space Administration. I S B N 978-0-16-090110-2 For sale by the Superintendent of Documents, U.S. Government Printing Office Internet: bookstore.gpo.gov Phone: toll free (866) 512-1800; DC area (202) 512-1800 90000 Fax: (202) 512-2104 Mail: Stop IDCC, Washington, DC 20402-0001 I S B N 978-0-16-090110-2 9 780160 901102
    • DRESSING FOR ALTITUDEU.S. Aviation Pressure Suits—Wiley Post to Space ShuttleDennis R. JenkinsNational Aeronautics and Space AdministrationHeadquarters300 E Street SWWashington, DC 20546NASA SP-2011-595
    • Library of Congress Cataloging-in-Publication DataJenkins, Dennis R. Dressing for altitude : U.S. aviation pressure suits-- Wiley Post to spaceshuttle / Dennis R. Jenkins. p. cm. -- (NASA SP ; 2011-595)ISBN 978-0-16-090110-21. Pressure suits--United States. 2. Space suits--United States. I.Title. TL697.P7J46 2012 629.13443--dc23 2012004448
    • Table of Contentsiii NASA 116 ATAGS and the F-22 262 A/P22S-2—Production USAF 118 Rediscovering the Progressive Full-Pressure Suitsv Foreword Arterial Occlusion Suit 264 Sidebar: The Evolving Pressure Suitvii Jack Bassick Biography 119 Summary Depot 279 A/P22S-3—A Navy Suit for theix Preface 121 4: Partial-Pressure Suits Air Forcexii Acknowledgments 121 Pressure Breathing 283 A/P22S-4 and A/P22S-6—Evolvingxiii Dedication 125 S-1—Genesis of the Partial-Pressure the Concept Suit 293 Boyles Law Suit15 1: Introduction 135 S-2 and T-1—Production Partial- 295 PHAFO—The StillBorn15 Horror Vacui Pressure Suits High-Altitude Flying Outfit18 Structure of the Atmosphere 141 MC-1—Featherweight Suit20 Atmospheric Pressure 146 MB-1 and MB-2—Ill-Fated Air 301 7: Special Project Suits22 Physiological Issues of High- Defense Command Suits 301 S901 and S970—Suits for Oxcart Altitude Flight 147 MC-3 and MC-4—Dragon Ladies 316 S-100—Hybrid Suit for the and Hustlers Original U-225 2: Mark Ridge, Wiley Post, 161 MC-3A Specials—Manhigh, 322 S901J—Initial Suit for Senior Crown and John Kearby Excelsior, and Stargazer 334 S1010—A Suit for the Dragon Lady25 Early Pressure Suits 165 CSU-2/P—Attempt to Improve 339 S1030—Improved Senior Crown Suits2835 Wiley Post and the Winnie Mae International Efforts 167 the MC-4 C-1A and C-4—Navy Capstan Suits 348 349 S1031—Improved Dragon Lady Suits S1031C—Common Suit i41 Aeromedical Pioneers 168 CSU-4/P and CSU-5/P—Bladders 350 S1034—Improved Common Suit43 The U.S. Army Rediscovers the Only 362 Sidebar: The Shrinking Industrial Base Pressure Suit 173 HAPS—NASA Dryden High-69 Summary Altitude Protective System 365 8: Space Shuttle Pressure Suits 366 ISSA and EIS—Stillborn Space Shuttle71 3: Acceleration Protection 179 5: Navy Full-Pressure Suits Suits72 The Physiology of Acceleration 215 Russell Colley, Again 374 S1030A—Ejection Escape System74 Human Centrifuges 218 Mark I (EES) Suits80 The Beginning of an Idea 220 Mark II 378 LEH—Launch Entry Helmet83 Australian Cotton 222 Mark III 382 S1032—Launch Entry Suits (LES) Aerodynamic Anti-G Suit 227 Mark IV 399 S1035—Advanced Crew Escape Suit86 Canadian Franks Flying Suit 231 Mark IV Suits for Strato-Lab (ACES)89 The Americans 233 Mark V 410 Comparing Columbia to an92 Berger Brothers 233 Project Mercury Spacesuits SR-71 Breakup96 The Worcester Connection105 Cutaway Suits 237 6: Air Force Full-Pressure Suits 413 Endnotes109 Postwar Suits 241 Lines of Nonextension110 TLSS and COMBAT EDGE 243 MC-2—A New Beginning 471 Index Dressing Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle Aviation Pressure Suits—Wiley | Dennis R. Jenkins
    • NaSa
    • NASASince its earliest days, flight has been about future is the workforce. Without these menpushing the limits of technology and, in many and women, technological advancementscases, pushing the limits of human endurance. would not be possible. Dressing for AltitudeThe human body can be the limiting factor in is designed to provide the history of thethe design of aircraft and spacecraft. Humans technology and to explore the lessons learnedcannot survive unaided at high altitudes. through years of research in creating, testing,There have been a number of books written and utilizing today’s high-altitude suits. Iton the subject of spacesuits, but the literature is our hope that this information will proveon the high-altitude pressure suits is lacking. helpful in the development of future suits.This volume provides a high-level summary Even with the closeout of the Space Shuttleof the technological development and opera- and the planned ending of the U-2 program,tional use of partial- and full-pressure suits,from the earliest models to the current high- pressure suits will be needed for protection as long as humans seek to explore high frontiers. iiialtitude, full-pressure suits used for modernaviation, as well as those that were used for The NASA Aeronautics Research Missionlaunch and entry on the Space Shuttle. The Directorate is committed to the training ofgoal of this work is to provide a resource on the current and future aerospace workforce.the technology for suits designed to keep This book and the other books publishedhumans alive at the edge of space. Hopefully, by the NASA Aeronautics Research Missionfuture generations will learn from the hard- Directorate are in support of this commit-fought lessons of the past. ment. Hopefully, you will find this book a valuable resource for many years to come.NASA is committed to the future ofaerospace, and a key component of thatTony SpringerLead, Communications and EducationNASA Aeronautics Research Mission Directorate
    • ivForeword
    • ForewordForewordThe definitive story of pressure suits began A key ingredient to successful pressure suit 50,000 feet, wearing their capstan partiallong ago and has involved a great many people programs has been the close collaboration pressure suits for extended periods of time,to obtain the present state of the art as this between vehicle designers, pressure suit often experiencing cabin decompressions,book well chronicles. Many of these people designers, and, most importantly, the aircrews which necessitated that they continue flyingwere visionaries who anticipated the need for themselves. Given that pressure suits are of in their pressurized suit. Thus began asuch highly specialized equipment long before necessity, totally encompassing, the importance concerted effort to make continuous pressureit could actually be employed in any practical of satisfying all human factors cannot be suit improvements as materials, processes,application. A remarkable number of pressure overstated. Just how effectively pioneering and technologies allowed, so as to maximizesuit designs were developed early on, the vast suit designers dealt with human factors is functionality and minimize suit-induced stressmajority of which never made it into flight, perhaps best illustrated by the fact that the and fatigue on the pilot to the extent possible.amounting to little more than science projects. first practical pressure suit design developedNonetheless, these early “experiments”informed later work, which led to practical for high-attitude flight above 50,000 feet (the capstan-operated partial pressure suit The first operational full-pressure suit employed (in the D-558-2 Douglas Sky- vpressure suits when they were needed for high- first employed in the X-1 rocket plane in the rocket) for flight above 50,000 feet was alsoaltitude flight. late 1940s) was subsequently employed in the result of a collaboration between suit untold numbers of aircraft all over the world, designers and the pilot (Scott Crossfield).All successful pressure suit designs have remaining in service until 1989 when the last This close collaboration continued on for thebeen the result of efforts to address a specific Lockheed U-2C aircraft was retired. development of the landmark full-pressureneed in a specific application, beginning suit for the X-15 program. The X-15 suit firstwith Wiley Post’s pressure suit designed for The snug-fitting, conformal nature of the employed link-net material, originally con-use in his Lockheed Vega, the Winnie Mae. capstan partial pressure suit necessitated a ceived for the neck section of early U-2 pilotLong considered the granddaddy of modern very close working relationship between suit helmets to aid pressurized mobility, for thepressure suits, interestingly, Post’s suit was designers and aircrews, thus fostering an entire restraint layer of the suit. This uniqueemployed principally for protection from ongoing awareness of human factors and their material greatly facilitated custom suit fittinghypoxia rather than decompression sickness, importance. This awareness became most and enhanced pilot comfort and remains insince his Lockheed Vega’s altitude ceiling was acute with the advent of the U-2 program, use to the present. Thus, the X-15 suit is really50,000 feet. wherein pilots were required to fly well above the granddaddy of modern-day pressure suits, Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Foreword as it led directly to the standardized military From the dawn of high-altitude flight, the The future of pressure suits remains to be seen; full-pressure suits that followed and continue cadre of people specializing in crew protection however, it is reasonably certain that man in service to the present. Further, the X-15’s for this extreme regime has remained relatively will continue to fly high and fast, and since high performance required that the pressure small and, consequently, cross fertilization he must wear something, it would seem suit be capable of withstanding exposure to of knowledge amongst the different programs prudent to wear an ensemble that affords a extreme altitudes, temperatures, and high-Q and disciplines was (fortunately) inevitable. large measure of safety as does a pressure suit ejections, thus setting the stage to satisfy simi- Thus, today’s advanced state of the art for (witness Lockheed test pilot Bill Weaver’s lar requirements for later programs, namely pressure suits is the result of many people’s SR-71 incident). The challenge is for designers the A-12, SR-71, XB-70, and Space Shuttle. dedicated work in government, industry, and to further expand the performance envelope of even academia. However, one program, in pressure suits by making them even more user- The development of a versatile thru-helmet particular, stands out for advancing the state of friendly through the use of new and emerg-vi feeding and drinking system and a reliable urine collection system in the late 1960s further the art of pressure suits over the past 56 years, the U-2 program. From the beginning in 1955, ing materials, processes, and technologies, such as those offered by the emerging field enhanced pilot comfort and performance. the U-2 program’s enlightened management of nanotechnologies. Leveraging such future Two later innovations aimed at reducing pilot has remained ever supportive of advancements technological advancements, while exercising stress and fatigue were the development of a in pilot’s protective equipment when/wherever due diligence in addressing human factors, will non-conformal, full-pressure helmet with a possible. At present, the U-2 program husbands quite certainly ensure a continued advance- moveable visor and breathable gas containers, the sole remaining national high-altitude pilot ment in the state of the art of pressure suits. both of which were originally developed for protection capability. the U-2 program but were quickly adopted by Jack Bassick NASA for the Space Shuttle. Director David Clark Company Incorporated Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Jack Bassick BiographyJack Bassick Biography Jack Bassick has worked closely with pressure variety of air and spacecraft applications, suits for over fifty years, beginning in 1961 being awarded a number of pressure suit as a physiological training instructor with related patents and receiving NASA Astronaut the United States Air Force before joining Corps’ prestigious Silver Snoopy Award for David Clark Company in 1965. Jack’s tenure his contributions to Astronaut safety. Jack at David Clark has included numerous represents the third generation of pressure suit assignments and responsibilities, including specialists at David Clark Company, following pressure suit field service at Area 51 with the in the footsteps of founder David M. Clark CIA’s A-12 Oxcart program and Edwards and his chosen successors, John Flagg and North Base with the Agency U-2 program. Joe Ruseckas. Appointed Director of Research Throughout his career, Mr. Bassick has and Development and elected Executive Vice participated in the research, development, qualification testing, production, crew President of David Clark Company in the late 1980’s, Mr. Bassick recently retired from vii training and field support of numerous active employment, remaining involved with partial and full pressure suit systems for a the company as a director. Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Preface
    • PrefacePrefaceAnybody who has watched many movies or of aviation pressure suits from the modern Aeronautics (NACA) effort, raised the state oftelevision shows has seen them: the ubiquitous beginning. Moreover, the company is also the art for partial-pressure suits, and the com-silver suits worn by pilots as they explore the the sole survivor among the original pressure pany’s early full-pressure suit was first used onunknown. They are called pressure suits, and suit manufacturers and was very enthusiastic the Douglas D558-2 program, which was aone can trace their lineage to famed pilot about telling the story. The other principal U.S. Navy-NACA effort. Major full-pressureWiley Post. player in modern American full-pressure suits, suit improvements were made for the X-15 B.F. Goodrich, has morphed so many times program, which was a USAF-Navy-NACAAbstractly, the remote ancestor of the mod- that the archives—other than a small col- venture. Ultimately, the Space Shuttle Pro-ern full-pressure suit is the “dry suit” used by lection at the University of Akron—for the gram, a uniquely NASA enterprise, becameturn-of-the-20th-century commercial salvage division that employed pioneering pressure- the most visible user of aviation pressure suits.divers. Interestingly, although conceptually suit architect Russell S. Colley could not besimilar, the two concepts—the diver’s dry located. Most of what remains are some minor There are several items of clothing that aresuit and the aviation full-pressure suit—areexactly the opposite functionally; the dry suit reports in various Government archives, and there are surprisingly few of those. Unfortu- relevant to high-altitude flight. All operate using a couple of different principles that ixensemble worn by divers protected the wearer nately, therefore, an important part of this produce similar results. The first garment isfrom the hazards of too much pressure (hyper- story is only lightly touched on. not directly related to high-altitude flight butbaric environment), whereas today’s aviation rather to protecting against high acceleration.counterpart protects the occupant from the When I began this project, Jack Bassick, Nevertheless, the “G-suit” is highly relevantconsequences of too little pressure (hypobaric the executive vice president of David Clark to this story since it was developed duringenvironment). In reality, diving suits have Company and a man with great experience World War II by many of the same people,played only a small role in the development of with pressure suits, commented that it was institutions, and companies that would go onaviation pressure suits, and then only prior to appropriate that the National Aeronautics to develop pressure suits. During the 1940s,World War II. and Space Administration (NASA) sponsor and even into the 1950s, it was difficult to this book. Although NASA seldom directly separate G-suits and pressure suits—bothMuch of this history centers on the David funded the development of aviation pres- were commonly designated “altitude suits” byClark Company for several reasons. Perhaps sure suits, Jack Bassick pointed out that the the military, and both were frequently calledmost importantly, Clark, and the company Bell X-1 program, a joint U.S. Air Force pressure suits, even by the agencies that werehe founded, has been involved in the concept (USAF)–National Advisory Committee on developing them (a G-suit does, after all, Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Preface apply pressure to the body). This sometimes air for the Americans and carbon dioxide lungs become unable to provide enough oxy- complicates the story, although I have tried to (CO2) for the Australians. It soon became genation of the blood due to the insufficient separate the activities as much as possible. clear that the airplane itself could provide driving pressure. Just prior to World War II, compressed air more efficiently than could researchers determined that to survive at the The G-suit, as finally developed, serves two a tank of CO2, and all G-suits eventually midaltitudes it was possible to force oxygen main purposes. The first is to prevent the switched to engine-mounted air sources. into the lungs under pressure. The problem pooling of blood in the lower extremities, was that the lack of air pressure outside the and the second is to provide firm abdominal The third way to apply pressure to the legs chest made it very difficult to exhale—pilots support to enhance the straining maneuver was, mostly, mechanical. Researchers at had to deliberately force the air out of their pilots use to raise their blood pressure and to Yale University and General Electric devel- lungs. It was unnatural and tiring and effec- support the chest cavity to prevent the shift- oped a capstan—essentially, a fabric tube that tively a reversal of the natural breathing pro- ing of major organs. Preventing the pooling ran along the legs—attached to a series of cess (i.e., one had to actively exhale and of blood, particularly in the legs, is accom- interdigitating tapes. As air pressure expanded inhalation became passive). A partial answer plished by applying external pressure on the the capstan, the tapes pulled the fabric tightly was a pressure vest that operated much like a thighs and calves to constrict the blood vessels, around the leg, constricting it. In theory this G-suit. A bladder located on the front (and hence increasing total peripheral resistance. should be more effective since it applies rela- sometimes back) of the chest inflated and The external pressure exerted by the G-suit tively uniform pressure around the entire cir- deflated in opposition to the pilot’s breath- cycles in proportion to the +Gz forces being cumference of the limb (most of the bladder ing (the bladder deflated as the pilot inhaled,x experienced by the wearer. Researchers tried three different approaches to generate the skin systems only applied pressure to the sides of the main muscle groups), but tests showed the allowing the chest to expand; as the pilot exhaled, the bladder inflated to force air out of counter-pressure. Two approaches used blad- capstans could not react quickly enough given the lungs). This balanced pressure-breathing ders placed against the skin that were covered the available pressure sources on airplanes. technique worked satisfactorily up to about by a layer of restraining cloth; as pressure The capstan G-suit was rather quickly forgot- 43,000 feet. inside the bladders increased, the bladders ten, although the technology later proved could not expand outward because of the critical to early partial-pressure suits. Next came pressure suits. There are two kinds restraining fabric, so they expanded inward of pressure suits: partial pressure and full pres- against the skin. Almost everybody has expe- The next item of protective clothing was the sure. David Clark, the man, once pointed out rienced a similar concept: the blood pressure pressure-breathing vest. The human body that these were not very good names, but they cuff, in the doctor’s office. requires a certain amount of oxygen to sur- are the ones that stuck. In a partial-pressure vive. As you fly higher, it becomes hard to suit, the counter-pressure is not as complete as The Canadians and Germans used water to receive this partial pressure of oxygen just by in a full-pressure suit, but it is placed so that fill the bladders, but this proved to be heavy breathing normal air at the reduced pressure shifts in body fluids are kept within reasonable and uncomfortable for the pilots. The Ameri- at altitude, so flyers switch to pure oxygen. limits. Essentially, a partial-pressure suit oper- cans and Australians used gas—compressed However, as altitude increases further, the ates much as a G-suit, except it covers more Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Prefaceof the body and operates for prolonged times. On the other hand, a full-pressure suit, which and vision, and can cause dizziness andThe suit works by applying pressure over the is an anthropomorphic pressure vessel, creates reduce muscle coordination. Without anmajor muscle masses and thorax while keeping an artificial atmosphere for the pilot. Unlike a oxygen supply, pilots can lose consciousnessthe joints relatively free of counter-pressure. partial-pressure suit, there is no direct mechan- in less than a minute after exposure to lowIn this way, by striking a balance between ical pressure on the body, and pressure breath- pressures at high altitudes.counter-pressure and limb freedom, sufficient ing is not required. Instead, a small volume ofmobility is retained to permit the use of the gas surrounds the pilot, and the body responds • Decompression sickness (also known assuit for limited periods. Partial-pressure suits as if the pilot is at some predetermined lower “aviator bends”): This includes severe jointalso need to provide substantial counter- altitude, generally between 25,000 and 37,000 pain caused by nitrogen coming out ofpressure to the chest to aid in pressure breath- feet. The pilot has to breathe pure (or mostly solution in blood and tissues as a result ofing. Two different types of partial-pressure so) oxygen, but it does not need to be forced a rapid decrease in atmospheric pressure.suits were developed. The first suits used into his lungs under high pressure, as with a Severe cases can result in death.the capstan principle to provide mechanical partial-pressure suit. Because the suit is pres-counter-pressure on the arms, legs, and across surized, it is often fairly stiff, limiting mobility. • Armstrong Line: The altitude (roughlythe shoulders and back. Capstans worked here In fact, providing sufficient mobility has been 63,000 feet) at which water goes from abecause they did not need to react particularly one of the continuing challenges for develop- liquid to a gas (i.e., boils) at body tempera-quickly, unlike the G-suit. These suits used ers. However, since the pilot is in a “normal” ture. Exposure above this altitude can causebladders—essentially, a pressure-breathing vest, atmosphere, he can wear the suit almost indefi- unconsciousness and result in rapid deathfitted around the chest. The second type of suitused bladders everywhere, eliminating the cap- nitely, at least from a physiological perspective. due to hypoxia, decompression sickness, and severe gas expansion. xistans. For the most part, researchers expected One type of pressure suit is not necessarily bet-partial-pressure suits to be emergency “get- ter than the other, and both partial pressure There are, of course, many other pieces of pro-me-down” suits to allow crews of high-altitude and full pressure suits are still in use around tective clothing that are intimately related toaircraft to return to safe altitudes following the world. Both type of suits have benefits and pressure suits, including helmets, gloves, boots,unexpected loss of cabin pressure. However, limitations and, by and large, pilots dislike and oxygen masks, plus ancillary equipmentthe suit could also support operations at high- both, even while acknowledging their necessity. such as regulators, controllers, and valves. Thealtitudes for a relatively limited time such as focus of this book is on the suits themselveswhen a crew depressurizes the cabin of a strate- All pressure suits protect against several physi- and why and how they were developed andgic bomber before entering a heavily defended ological risks associated with high-altitude fielded. The other components are covered inarea, or when a research pilot takes an experi- flying, including: passing as seems appropriate, but their detailedmental aircraft to high altitude for a few min- development history is left to others.utes of testing. Almost heroically, U-2 pilots • Hypoxia: The decrease of oxygen in thewore partial-pressure suits for hours while fer- blood caused by reduced atmospheric pres- It should also be understood that the focusreting out secrets over the Soviet Union.1 sure can affect mental capacity, judgment, of this book is aviation pressure suits, not Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Preface spacesuits. Although the two pieces of clothing ACKNOWLEDGMENTS TD Barnes (Roadrunners Internationale), are generally thought to be the same, in reality Roger J. Barnicki (NASA/Dryden Flight they differ in several ways. A spacesuit has to No book can be produced in a vacuum Research Center, retired), Dan Barry (David provide additional protection from radiation (pun intended), especially one that attempts Clark Company), Thomas W. Bowen (9th (although some pressure suits also provide lim- to cover 75 years of technology development. Physiological Support Squadron, Beale Air ited radiation protection) and impact strikes The project would not have gotten started Force Base), Steven Bromley (Gentex Corp.), (from micrometeorites and orbital debris) without Tony Springer at NASA Headquar- Dr. Fred Buick (Defence Research and Devel- and also be more self-contained since there ters. Many people helped during my research, opment Canada), Tony Chong (Northrop is often not a vehicle attached to the suit to and I am indebted to each of them. Grumman), Dr. Jonathan B. Clark, William J. provide oxygen and power. A full-pressure suit Close (NASA/Johnson Space Center), normally does not provide its own oxygen or In particular, a small group of people went Kenneth S. Collins (Dutch 21), Daniel power except for very limited times after an above and beyond the call, including: Robert Coulom (Hamilton Standard), Regina ejection or bailout, and it usually has some R. “Bob” Banks (David Clark Company), (Conrad David Clark Company), Rob sort of anti-suffocation feature in which the John W. “Jack” Bassick (David Clark Com- Coppinger (Flight International), A. Scott helmet vents to the atmosphere if the oxygen pany), Ed Dubois (David Clark Company), Crossfield, William H. Dana (NASA/ supply is exhausted. In addition, most pressure Dennis Gilliam, Joseph A. Ruseckas (David Dryden), John J. Devine, Jr. (Government suits provide some sort of exposure protection Clark Company), Dr. Jan Stepanek (Mayo Documents Department, Boston Public in case the pilot finds himself in water after Clinic), and Brett Stolle (National Museum Library), Duane W. Deal (Brig. Gen, USAF,xii an ejection. Pressure suits, partial and full, can allow a pilot to survive in a vacuum for a lim- of the United States Air Force). Ret.), Archie Difante (Air Force Historical Research Agency), John Dodson (University ited period, but that is not their primary focus. Others who graciously contributed include: of Sydney), Gail E. Farr (National Archives The history of spacesuits has been well covered Aric Ahrens (Paul V. Galvin Library), Research Agency Mid Atlantic Region), Gail in literature; this book attempts to fill the void Tom Anderson (SpaceAge Control), William Fithian (Government Documents Depart- regarding aviation pressure suits. Ayrey (ILC Dover), Dr. James P. Bagian, ment, Boston Public Library), Alan Freeman Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Preface(David Clark Company), Steve Gaut (Federal- Murray (Dutch 20), Jennifer Ross-Nazzal DEDICATIONMogul), Christian Gelzer (NASA/Dryden), (NASA/Johnson Space Center, HistorySandy Gettings, Terry Greenfield (NASA/ Office), William Norton, Kenneth Przybyla During this project, two men intimatelyKennedy Space Center), Richard H. Graham (Carleton Controls), Don Pyeatt, Gary Ray familiar with pressure suits passed away.(Col., USAF, Ret.), Wes Henry (National (NASA/Kennedy Space Center), Dr. Sally Joseph A. Ruseckas, from the David ClarkMuseum of the United States Air Force), John K. Ride, Dr. Erik L Ritman (Mayo Clinic), Company, helped design many of the pressureC. Harper (Chevron), Jan K. Herman (Bureau Dr. Angus H. Rupert (U.S. Army Aeromedi- suits described in this book, while USAF testof Medicine and Surgery Historian), Craig cal Research Laboratory), Bruce W. Sauser pilot Maj. Gen. Robert M. White made goodA. Holbert (University of Akron), Marty (NASA/Johnson Space Center), Carlton F. use of the suits as he became the first man toIsham, Eliza L. Johnson (NASA/Johnson “TC” Thomas (USA/Johnson Space Center), fly a winged aircraft above Mach 4, Mach 5,Space Center), Linda F. Jones (Chevron), Kenneth S. Thomas (Hamilton Standard), and Mach 6 and higher than 200,000 andDonald Lacey (ILC Dover-Johnson Space Tommy Thomason, Malcom V. “Mike” Todd 300,000 feet. I had the good fortune to countCenter), Tony R. Landis (NASA/Dryden), (Red Bull Stratos), Lucien Van Oosten (Gen- both men as friends. They made untoldIvy Leaf (Webmaster at Corsetiere), Denny tex Corp.), Col. Donald J. White (USAF/ contributions to aviation, and both will beLombard (Lockheed Martin, Ret.), Michael HQ), Maura White (NASA/Johnson Space missed. Godspeed.J. Lombardi (Boeing Historian), Betty J. Love Center), Lt. Col. Charles P. Wilson (USAF,(NASA/Dryden, Ret.), Joseph D. Malone Ret.), Ronald C. Woods (NASA/Kennedy(David Clark Company), Daniel R. McCarter Space Center), and Dr. James O. Young(David Clark Company), Jewel M. Melvin(Air Force Material Command/576th Air- (Air Force Flight Test Center, History Office). xiiicraft Sustainment Squadron), Marcel Meyer(Fédération Aéronautique Internationale),Roger Mott (Emil Buehler Library), MikeMoore (Lockheed Martin), Francis J. “Frank” Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • 1
    • Chapter 1: Introduction1: IntroductionOne of the unidentified authors of an Air shrinking planet and ventured into the handheld water plungers, with inconclusiveForce history of the Wright Air Development vast emptiness of space. In the interim, the results.3 Plato (427–347 B.C.E.), mathemati-Center wrote an epilogue that conveyed the altitude suit appeared to be the inevitable cian, writer of philosophical dialogues, andawe associated with aviation pressure suits armor of man as he strove to continue his founder of the Academy in Athens, thought theduring the mid-1950s. climb from the caves to the stars.1 idea of a vacuum inconceivable. He believed that all physical things were instantiations of an The high point in the development of Space Shuttle astronauts who donned their abstract Platonic ideal and could not imagine the altitude suit was reached on 17 June David Clark Company S1035 full-pressure an “ideal” form of a vacuum. Aristotle (384– 1954 when Maj. Arthur Murray rode suits were living proof. 322 B.C.E.), philosopher, student of Plato and the rocket-propelled X-1A to an altitude teacher of Alexander the Great, believed that in excess of 90,000 feet. When Murray HORROR VACUI a vacuum was a logical contradiction: nothing reached the peak of his record setting could not be something. The common view, flight, he was atop more than 97 percent of the atmosphere on the planet. Outside Vacuum, adjective; a space entirely devoid of matter; an enclosed space attributed to Aristotle and held true for a mil- lennium, that nature abhorred a vacuum was 15 the cabin of the X-1A, the rarified air was from which matter, esp. air, has been called horror vacui (literally, a fear of empty only about two percent as dense as that partially removed so that the matter spaces).4 It all made perfect sense at the time. at sea level. For all practical purposes, he or gas remaining in the space exerts was in the airless environs of outer space. less pressure than the atmosphere.2 In medieval Europe, the Catholic Church, a While he did not use the high altitude suit major influence on science and philosophy, that he wore, he proved that a man could Although difficult to imagine today, man held the idea of a vacuum to be heretical since survive outside the earth’s atmosphere for debated the question of whether a vacuum the absence of anything implied the absence short periods if he took along his own could exist for centuries. Ancient Greek phi- of God, and harkened to the void that existed environment. The lesson for the future losophers did not admit to the existence of a prior to the story of Genesis. The Inquisition was patent: The high altitude suit which vacuum, asking themselves “how can ‘nothing’ made certain this idea was held true. had evolved in the first decade after World be something?” Islamic philosopher Al-Farabi War II probably would—in one form (970–850 B.C.E.) appears to have conducted However, this began to subtly change in 1277, or another—accompany man when he the first recorded experiments concerning the when Bishop Étienne Tempier of Paris decreed finally escaped the confines of his rapidly existence of the vacuum when he investigated there were no restrictions on the powers of Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 1: Introduction God, which led to the conclusion that God ideas but kept an extensive journal, from which Perhaps more important was that this experi- could create a vacuum if He so wished.5 So, his brother published some of his observations ment left a space above the water in the tube although the concept of a vacuum was no in 1644. However, given the relative obscurity that had no opening for air to refill. Berti longer heretical, neither was it much men- of Beeckman, this went largely unnoticed. In believed the space above the water was a tioned. Another 400 years would pass before 1615, the Tuscan mathematician, astronomer, vacuum, although the followers of Aristotle the concept of a vacuum was anything but a and philosopher Galileo Galilei (1564–1642) vigorously contested the claim. One of the philosophical discussion, usually conducted wrote, “that all the air … weighs nothing.”7 most vocal was René Descartes (1596–1650), in private. a French philosopher and scientist who argued Against this background, the Italian Giovanni that the space was filled with a substance called From the science of the 21st century, it is dif- Batista Baliani (1582–1666), among others, aether, which was able to flow through tiny ficult to understand how a sensible concept noted that pumps would not draw water higher pores in the tube to replace the receding water.9 of a vacuum could emerge without a cor- than 34 feet and siphons would not work over responding concept of pressure. Yet, it took hills of the same height. Baliani described this Magiotti apparently mentioned this experi- several hundred years for the two ideas to be effect in a letter to Galileo, who responded with ment to Evangelista Torricelli (1608–1647), linked. Interestingly, despite the science of the usual explanation: the pump or siphon cre- who had been Galileo’s assistant for the last the day not understanding the physics behind ated a partial vacuum, and horror vacui caused 3 months of the philosopher’s life. Torricelli the device, suction pumps were becoming water to rush in to fill the void. Nature would had radically different theories about why increasingly common devices used to move not allow the partial vacuum to exist long pumps and siphons worked and decided in16 water. The popular understanding was that these devices created a partial vacuum on one enough to move water higher than 34 feet. 1643 to duplicate much of Berti’s experi- ment to prove those theories. In a book writ- end, and water rushed from the other end to Baliani, however, did not accept this answer ten 300 years later, Isaac Asimov provided a fill the void in accordance with horror vacui. and believed that a vacuum was possible. description of Torricelli’s experiment: He also believed that air had weight. To Some questioned this explanation. An anony- test Baliani’s theories, some time prior to It occurred to Torricelli that the water was mous 13th century pupil of German philoso- 1643, Gasparo Berti and Raffaello Magiotti lifted, not because it was pulled up by the pher and mathematician Jordanus de Némore built a 36-foot tube, filled it with water, and vacuum, but because it was pushed up (1225–1260) understood that pressure in a plugged both ends. They placed one end of by the normal pressure of air.… In 1643, liquid increased with depth, but the publica- the upright tube in a basin of water, removed to check this theory, Torricelli made use tion of Némore’s book in which the discussion the bottom plug, and watched water pour of mercury. Since mercury’s density is appeared was delayed for three centuries.6 Inde- out into the basin. However, only part of the 13.5 times that of water, air should be pendently, Dutch philosopher Isaac Beeckman water in the tube flowed out, and the level of able to lift it only 1/13.5 times as high (1588–1637) correctly theorized that air pres- the water inside the tube stayed at 34 feet, the as water, or 30 inches. Torricelli filled a sure was what caused a water pump to work, same height others had observed as the limit 6-foot length of glass tubing with mer- not horror vacui. Beeckman did not publish his of a siphon.8 cury, stoppered the open end, upended Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 1: Introduction it in a dish of mercury, unstoppered it, Having replicated the experiment, Pascal ques- In 1650, German scientist and politician and found the mercury pouring out of tioned what force kept some mercury in the Otto von Guericke (1602–1686) invented the tube, but not altogether: 30 inches tube and what filled the space above it. Fol- the first vacuum pump and demonstrated of mercury remained, as expected.10 lowing more experimentation, in 1647 Pascal the force of air pressure with dramatic published Experiences nouvelles touchant le experiments. The most famous used a pair ofIn conducting this experiment, Torricelli vide,12 which detailed rules describing to what 20-inch-diameter copper hemispheres14 withhad built the first mercury barometer and degree various liquids could be supported by mating rims sealed with grease. Guericke useddeveloped a convincing argument that the air pressure. It also provided reasons why it his pump to remove the air in the enclosurespace at the top of the tube was a vacuum. was indeed a vacuum above the column of liq- and then harnessed a team of eight horses toThe height of the column was limited to the uid in a barometer tube. Science was, slowly, each half and showed that they were not ablemaximum weight that atmospheric pressure supplanting philosophy. to separate the hemispheres. When Guerickecould support. In honor of his contributions, let air into the enclosure, the halves easilyhis name was given to one of the early However, Pascal went further. If, as he and separated. He repeated this demonstration inmeasures of pressure. Oddly, however, unlike Torricelli suspected, air had weight caused 1663 at the court of Friedrich Wilhelm I ofKelvin and Pascal, who were honored using by the miles-thick atmosphere, it should Brandenburg in Berlin, using 24 horses.15their full names, only half of Torricelli’s was decrease at higher altitudes. Pascal wrote to hisused, and then without a leading capital brother-in-law, Florin Perier, who lived near With his experiments, Guericke dramaticallyletter: torr. Despite the significance of the the Puy-de-Dôme volcano in south-central disproved the hypothesis of horror vacuiexperiment, it took 20 years for the firstfull account to be known. In “De motu France, requesting he perform an experiment. Perier was to take a barometer up the Puy-de- and demonstrated that the pressure of the surrounding fluids pushed substances 17gravium,” which was published as part of Dôme and make measurements along the way instead of a vacuum pulling them. Later,the 1644 Opera Geometrica, Torricelli also of how high the column of mercury stood. Robert Boyle (1627–1691) and Robert Hookeproved that the flow of liquid through an In 1648, Perier meticulously carried out the (1635–1703) improved Guericke’s design.opening is proportional to the square root experiment and found that Pascal’s predictions In 1659, using his and Hooke’s Machinaof the height of the liquid, now known as were correct: the mercury barometer stood Boyleana, or Pneumatical Engine, BoyleTorricelli’s Theorem.11 lower at higher altitude.13 The Puy-de-Dôme began a series of experiments on the properties experiment ultimately caused the Aristotelian of vacuum. Boyle published an account ofAs important as Torricelli’s contribution philosophers to admit defeat and concede these in 1660 as “New Experiments Physico-was, the Aristotelian philosophers held fast, that air had weight. Within the International Mechanical, Touching the Spring of the Air,and it would take another legendary scientist System of Units (abbreviated SI from the and its Effects.”16 Among the critics of theseto finally put the debate to rest. By 1646, French “Le Système International d’Unités”), experiments was a Jesuit, Franciscus LinusBlaise Pascal (1623–1662), a French mathema- the Pascal (Pa) replaced the torr as the standard (1595–1675), and it was while answering histician, physicist, and philosopher, had learned measurement of pressure—this time using the objections that Boyle made his first mentionof Torricelli’s experiments with barometers. entire capitalized surname. that the volume of a gas varies inversely to Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 1: Introduction the pressure of the gas. Today this is known as The atmosphere consists of several concentric The troposphere contains water vapor and Boyle’s Law. layers, each displaying its own unique char- the vast majority of weather happens in this acteristics, known as spheres. Thermal vari- layer. The tropopause is the atmospheric Oddly, the study of vacuum then, largely, ances within the atmosphere help define these boundary between the troposphere and the lapsed until 1850, when August Toepler spheres. Between each of the spheres is an stratosphere. Going upward from the surface, (1836–1912) invented an improved mercury imaginary boundary, known as a pause.18 it is the point where air ceases to cool with piston pump called, logically enough, the height and becomes almost completely dry. Toepler pump. Then, in 1855, Heinrich The troposphere extends from sea level to Geissler (1814–1879) invented the mercury about 26,500 feet over the poles and nearly The stratosphere extends from the tropopause displacement pump and achieved a record 52,500 feet above the equator. Temperatures to roughly 160,000 feet (about 30 miles). Avia- vacuum of about 10 Pa (0.1 torr). A number decrease 3.6 degrees Fahrenheit (ºF) for each tion pressure suits, the subject of this book, are of electrical properties become observable 1,000 feet in altitude in the troposphere and meant to allow humans to survive in this layer, at this vacuum level, allowing Geissler continue to decrease until the rising air mass although many will function at higher altitudes. to invent the basic technologies behind achieves an altitude where temperature is in The stratosphere is subdivided into two regions fluorescent tube lights, vacuum tubes, and, equilibrium with the surrounding atmosphere. based on their thermal characteristics. Although ultimately, cathode ray tubes. Shortly after this, Hermann Sprengel (1834–1906) Table 1—Percentages of Atmospheric Gases invented a continuously operable vacuum18 pump, naturally called the Sprengel pump. Finally, the concepts of pressure and vacuum Gas Nitrogen Symbol N2 Volume (percentage) 78.0840 were well established.17 Oxygen O2 20.9480 Argon Ar 0.9340 STRUCTURE OF THE ATMOSPHERE Water Vapor H2O 0.4000 All of this experimentation, in some form, Carbon Dioxide CO2 0.0314 concerned the atmosphere. The atmosphere Neon Ne 0.0018 is the gaseous envelope that surrounds Helium He 0.0005 Earth from sea level to an altitude of about Methane CH4 0.0001 120,000 miles, held in place by gravity. With- out this envelope of gas, life as we know it Krypton Kr 0.0001 could not exist. The atmosphere provides Hydrogen H <0.0001 breathing air and protection from ultraviolet radiation, and it acts as a layer of insulation to Source: National Oceanic and Atmospheric Administration at maintain a relatively constant temperature. http://esrl.noaa.gov/gsd/outreach/education/climgraph/index.html Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 1: Introductionthese regions differ thermally, the water vapor of fast-moving jet streams, both here and in Rising temperatures characterize the secondcontent of both is virtually nonexistent. the upper regions of the troposphere, cause region, which contains the ozone layer. This the turbulence traditionally associated with serves as a double-sided barrier that absorbsThe first region is the isothermal layer where the stratosphere. harmful solar ultraviolet radiation whiletemperature is a constant −67 ºF. The presence allowing solar heat to pass through unaffected. Table 2—Atmospheric Data Altitude Atmospheric Pressure Atmospheric Pressure Oxygen Partial- Temperature Time of Useful (feet) (psi) (mm Hg) Pressure (mm Hg) (ºF) Consciousness 100,000 0.15 8 2 −51 0 90,000 0.25 13 3 −56 0 75,000 0.50 27 6 −65 0 63,000 0.73 47 10 −67 0 50,000 1.69 88 18 −67 0–5 seconds 43,000 40,000 2.40 2.72 123 141 26 30 −67 −67 5–10 seconds 10–20 seconds 19 35,000 3.50 179 38 −66 30–60 seconds 30,000 4.36 226 47 −48 1–3 minutes 25,000 5.45 282 59 −30 3–5 minutes 20,000 6.75 349 73 −12 10–20 minutes 18,000 7.34 380 80 −5 20–30 minutes 15,000 8.30 429 90 5 30+ minutes 10,000 10.11 553 116 23 Nearly Indefinitely 7,000 11.30 587 123 34 Indefinitely Sea Level 14.69 760 160 59 Indefinitely Data for an ISO standard day (59 °F / 15 °C) at 40 degrees latitude. Source: U.S. Naval Flight Surgeon’s Manual, Naval Aerospace Medical Institute, Third Edition, 1991. Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 1: Introduction In addition, this region reflects heat back and carbon dioxide. Table 1 shows the As designed, human beings are not well toward the surface of Earth, keeping the lower concentrations of gases commonly found in equipped to operate at the altitudes normally regions of the atmosphere warm, even at night the atmosphere.19 found in the higher mountainous regions during the absence of significant solar activity. of Earth, let alone in the upper atmosphere. Although a vital ingredient in the chain of An average person in decent health normally The mesosphere extends from the stratopause life, nitrogen is not readily used by the human has no problem with daily activities at to an altitude of 264,000 feet (50 miles). body. However, respiration saturates body altitudes below 10,000 feet, although Temperatures decline from a high of 26 ºF fluids and tissues with nitrogen, which can disorders impacting oxygen uptake, delivery, at the stratopause to nearly −171 ºF at the result in evolved-gas disorders because of the or utilization (such as smoking or lung mesopause. Consisting of meteor dust and decreased solubility of nitrogen at higher disease) can result in shortness of breath at water vapor and shining only at night, nocti- altitudes due to lower ambient pressure. any altitude. Above 10,000 feet, even well- lucent clouds are a visible characteristic of conditioned individuals feel the effect of this atmospheric layer. Oxygen is the second most plentiful gas in exertion much quicker than at sea level. As the atmosphere. Respiration unites oxygen altitude increases, there are physiological The thermosphere, characterized by tempera- and sugars to meet the energy requirements of limits to the maximum time a human can tures that vary in direct relation to solar activ- the body, and the lack of oxygen in the body continue to function. ity, extends from the mesopause to an altitude at altitude will cause drastic physiological of about 310 miles. Temperature ranges from effects that can result in death. To function ATMOSPHERIC PRESSURE20 −171 ºF at the mesopause to 2,700 ºF during periods of extreme solar activity. Another char- normally, the healthy human body requires approximately 3 pounds per square inch (psi) Standard atmospheric pressure, or barometric acteristic of the thermosphere is the presence of oxygen pressure in the lungs—conveniently, pressure, is the force (that is, weight) exerted of charged ions that are the result of high- about what is available at sea level (21 percent by the atmosphere at any given altitude. speed subatomic particles emanating from the of 14.7 psi is 3.1 psi). Atmospheric pressure decreases with increas- sun. These particles collide with atmospheric ing altitude, making barometric pressure gas atoms and split them apart, resulting in a Carbon dioxide is the product of cellular respi- of great concern to aircrews because oxygen large number of charged particles (ions). ration in most life forms. Although not present diffusion in the body depends on total in large amounts, CO2 in the atmosphere plays barometric pressure.20 The exosphere extends from the thermopause a vital role in maintaining the oxygen supply to 120,000 miles, and from most perspectives, of Earth. Through photosynthesis, plants use There are many units of pressure, including it is indistinguishable from outer space. CO2 to create energy and release oxygen as a millimeters of mercury (mm Hg, for all byproduct. Because of animal metabolism and intents, the same as a torr, and used in this The atmosphere contains many gases photosynthesis, CO2 and oxygen (O2) supplies book), inches mercury (in. Hg), inches of (although only a few are essential to human in the atmosphere remain constant. water (in. Aq), torr, Pascals (and its standard survival), including mostly nitrogen, oxygen, metric derivatives), psi, and the Standard Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 1: IntroductionAtmosphere (atm). The approximate gases remains constant with increasing altitude, conscious for any useful time. Breathingconversations are as follow: each gas’s partial pressure decreases in direct 100 percent oxygen at 34,000 feet is proportion to the total barometric pressure. physiologically equivalent to breathing air at 1 atmosphere = 760 mm Hg (torr) = 14.69 sea level. Breathing 100 percent oxygen at psi = 101.325 kilopascals (kPa). Changes in the partial pressure of oxygen dra- 40,000 feet is equivalent to breathing air at matically affect respiratory functions within 10,000 feet. At altitudes between 40,000 andA close relationship exists between atmo- the human body, and rapid decrease in the 50,000 feet, pressure breathing must be usedspheric pressure and the amount of the vari- partial pressure of oxygen may quickly result wherein the breathing cavity, for exampleous gases in the atmosphere, an effect known in physiological impairment. Although a per- the helmet, is maintained at a small positiveas Dalton’s Law of partial pressures. Dalton son may not notice this impairment at lower pressure. This increases the ability of the bodydemonstrated that the pressure exerted by a altitudes, the effects are cumulative and grow to absorb the oxygen into the blood stream.mixture of ideal (nonreacting) gases is equal to progressively worse as altitude increases. Fortu- At altitudes above 50,000 feet, humans mustthe sum of the pressures that each gas would nately, within certain limits, the human body resort to using pressure breathing and a partial-exert if it alone occupied the space filled by can acclimatize and hence improve its perfor- pressure suit or, alternately, a full-pressurethe mixture. Put another way, the pressure of mance in a hypoxic environment over days suit. Being at very high altitudes without aeach gas within a gaseous mixture is indepen- and weeks. Decreases in the partial pressure of pressure suit is extremely dangerous and resultsdent of the pressures of the other gases in the nitrogen (N2), especially at high altitude, can in a condition in which the free nitrogen inmixture. The independent pressure of each lead to a decrease in the solubility of N2 in the the blood bubbles from solution, resulting ingas is termed the partial pressure of that gas.Mathematically, Dalton’s Law is expressed as: body and result in decompression sickness. severe organ injury or death in minutes.22 21 Decompression sickness (DCS), also called There are two absolutes when dealing with Pt = PN + PO2 + PCO2 + … (assuming the bends and caisson disease arises from the humans and ever-decreasing atmospheric constant volume and temperature) precipitation of dissolved gasses into bubbles pressures: the first occurs at about 43,000 feet inside the body on depressurization. DCS altitude and the second at 63,000 feet.23In this equation, Pt represents the total most commonly refers to a specific type ofpressure of the mixture and PN, PO2, scuba diving hazard but may be experienced in The first, 43,000 feet, is the altitude atPCO2 represent the partial pressures of each other depressurization events such as working which it is impossible, without resorting toindividual gas (nitrogen, oxygen, and carbon in caissons, flying in unpressurised aircraft, pressure breathing, for the lungs to absorbdioxide, in this example). and space-based extra-vehicular activity. Its enough oxygen to sustain oxygenation and effects may vary from joint pain and rashes to consciousness, even if breathing 100 percentDalton’s Law illustrates that increasing altitude paralysis and death.21 oxygen. Pressure breathing is pure oxygenresults in a proportional decrease of partial delivered under pressure—usually less thanpressures of gases found in the atmosphere. At altitudes above 28,000 feet, the body 1 psi (52 mm Hg) but enough to physicallyAlthough the percentage concentration of requires 100 percent oxygen to remain force the gas into the lungs. Unfortunately, Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 1: Introduction it is necessary to forcefully exhale the carbon PHYSIOLOGICAL ISSUES OF HIGH- supplemental protection for the crew. The dioxide, and then relax sufficiently to allow ALTITUDE FLIGHT physiological effects of a rapid decompres- more pressurized oxygen to enter the lungs. sion include acute hypoxia, effects on the As Donn Byrnes describes in Blackbird Rising, The homeostatic responses in humans to gas-containing cavities of the body, decom- “This pressure breathing is conducted under sudden exposure to low barometric pressures pression sickness, thermal exposure, and ebul- very low mask pressure, usually equivalent to are limited in their adaptive capabilities since lism (formation of bubbles in body fluids). the weight of a column of water about five this hostile environment is foreign to human Less rapid but equally debilitating effects of inches high. Imagine blowing a five-inch plug physiology. Hence, there is no opportunity unpressurized flight at high altitude include of water out of your snorkel in the swimming for a sufficient adaptive response. Exposure hyperventilation, fatigue, reduction in effec- pool each time you exhaled, and doing that results in a rapid onset of unconsciousness tive circulating blood volume, and fainting for a couple of hours or more.” It is hard unless otherwise protected by artificial means. associated with pressure breathing. Also, work and represents a complete reversal of If there should be a sudden or even slow loss acceleration forces during high-speed egress a human being’s normal physiology with of cabin pressurization at altitudes above (ejection) can have a profound consequence respect to breathing. Essentially, nobody can 40,000 feet, even while breathing 100 percent on the skeletal structure and the cardiovas- function well under pressure breathing for any oxygen at ambient pressures, the time of cular system. All of these reactions can have prolonged length of time, even with specially useful consciousness (TUC), the duration in potentially grave effects upon aircrew perfor- designed suits that assist with exhalation.24 which the pilot can perform basic emergency mance and mission effectiveness and all are tasks, begins to shrink. At 40,000 feet, avoidable by the employment of appropriate22 The second absolute is more frightening. At approximately 63,000 feet, called the Arm- breathing pure oxygen at ambient pressure, the TUC is theoretically indefinite (ignoring life support equipment and adequate training. Most pressure suits maintain the crewmember strong Line, pressure decreases to only 5 per- decompression sickness). This ability decreases at an equivalent altitude of approximately cent of sea level. The vapor pressure of water rapidly, and an increment of only 3,000 feet 34,000 feet breathing 100 percent oxygen, (47 mm Hg) at this altitude is the same as the (to 43,000 feet) makes it necessary to employ which is roughly equivalent to breathing sea atmospheric pressure (47 mm Hg) and water pressure breathing to have any TUC. By level air, thereby preventing most of these boils at the normal temperature of the human 50,000 feet, even breathing pure oxygen at problem areas.27 body (98.6 ºF). It is important to note that ambient pressure provides less than 5 seconds this applies to unconfined water, such as saliva TUC. The physiology and biochemistry of Hypoxia: Altitude hypoxia results when the and tears. Normal human diastolic blood pres- hypoxia in humans is beyond the scope of oxygen partial pressure in the lung falls below sure is sufficiently high that, contrary to oft- this book, and only the pertinent details are that comparable to sea level. However, it is repeated myth, a person’s blood will not boil summarized here.26 not generally significant until the alveolar in a vacuum, although there are many other oxygen tension falls below a 10,000-foot environmental threats such as hypoxia, cold, In high-altitude flight, a structural failure equivalent. At 10,000 feet, the reduced ability and trapped gas expansion that will quickly kill in a pressurized cabin or loss of cabin pres- to learn new tasks can be measured and con- an unprotected human above this altitude.25 sure control would be catastrophic without sequently 10,000 feet is used as the altitude Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 1: Introductionthat supplemental oxygen is considered neces- equilibrium with ambient pressure. When tearing and blinking during pressure breathing,sary.28 As the partial-pressure of oxygen in the ambient pressure is reduced, nitrogen bubbles which effectively blinds the crewmember.32inspired air continues to drop, the signs and form in the body tissues. If the drop in pres-symptoms of hypoxia become more evident sure is not too great or too fast, bubbles Thermal Extremes: The effects of the lowand include loss of peripheral vision, skin evolved in the tissues are safely carried to temperatures following loss of cabin pressuresensations (numbness, tingling, or hot and the lungs by the vascular system, where the at high altitude can cause impaired functioncold sensations), cyanosis, euphoria and evolved nitrogen is eliminated. Prolonged and eventual tissue damage to exposed regionseventually unconsciousness at higher altitudes. exposure to altitudes in excess of 25,000 feet of the body; or, if exposure occurs over aUp to an altitude of 34,000 feet, increasing may lead to one or more of the symptoms of longer duration, it could cause a drop in corethe percentage of oxygen allows an approxi- DCS, such as the bends, chokes, and circula- temperature causing a progressing impairmentmation of sea level oxygen equivalent. Above tory and neurological disturbances. Recent of performance followed by unconsciousness40,000 feet, breathing 100 percent oxygen studies have established the need for increas- and, eventually, death. An aircrew memberwithout additional pressure is not sufficient ing the pressure differential from 5 to 7 psi in wearing normal flying clothing with a maskfor efficient aircrew performance. Pressure future aircraft. Air Force researchers believe and gloves will not suffer any serious damagebreathing is required and is accomplished this increased pressure differential provides during a short exposure (5 minutes) to theby use of an oxygen system that delivers less risk of DCS during prolonged exposure to lowest temperature conditions encountered100 percent oxygen at greater than ambient cabin altitudes greater than 20,000 feet.31 at high altitude. Exposure beyond this timepressures. However, the pressures needed will lead to more severe peripheral cold injuryto sustain consciousness above 50,000 feetrapidly become intolerable.29 Ebullism: When the total barometric pressure is less than the vapor pressure of tissue fluid at unless appropriate clothing and heating gar- ments are worn. The garment must also pro- 23 body temperature (47 mm Hg), vaporization tect against heat when the temperatures onMechanical Effects: During a cabin depres- of the body fluids occurs. This occurs in the the outer surfaces of Mach 3 aircraft approachsurization, gases trapped within the intestinal nonpressurized portions of the body at alti- 560 ºF, and it also must protect against thetract, nasal sinuses, middle ear, and lungs tudes above 63,000 feet. However, exposure thermal pulse of ejection at Mach 3.33will expand. The magnitude of the effect of peripheral regions of the body (e.g., theon the gas-containing cavities of the body is hands) to pressures less than the vapor pres-directly proportional to the range and rate sure of the tissue fluids leads to vaporizationof change of pressure. Serious consequences of these fluids with little or no impairment ofresult when there is an occlusion or partial performance. When combined with low envi-occlusion between a gas-containing cavity ronmental temperatures, the evaporative cool-and the environment.30 ing associated with vaporization may accelerate freezing and drying of exposed tissues. WhileDecompression Sickness: Body tissues con- wearing only a mask for short exposures abovetain dissolved gas, principally nitrogen, in 63,000 feet, vision is affected as a result of Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • 2
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby2: Mark Ridge, Wiley Post, and John KearbyPressure suits, usually called spacesuits by the seemingly was the first to suggest that a suit be used) helmet split vertically, hinged on onepublic (although these are but one example similar to the diver’s ensemble could protect side, and latched on the other. The helmet wasof this type of garment), are essentially taken an aviator at high altitudes. There appeared, attached to the suit via bolts “or other securingfor granted today. Seventy-five years ago, they however, to be little immediate need for such elements” and had an oxygen hose connectedwere the stuff of science fiction. These suits a garment. The normally aspirated piston- to its back. Under the outer coveralls wasserve several necessary purposes, with sup- powered airplanes of the era were incapable an inflatable bladder that provided counter-plying the correct partial pressure of oxygen of altitudes much in excess of 20,000 feet, pressure to the chest. The suit buttoned up thethe most obvious, although masks or full-face and the major concern at the time was simply front like single-piece long underwear and didhelmets can also accomplish this somewhat keeping the pilot warm. However, the increas- not include integral gloves or boots, terminat-less efficiently, at least at the middle altitudes. ing use of supercharged engines during the ing instead with elastic cuffs at the wrists andTheir most important purpose, however, is late 1920s led to the first serious studies into ankles. Conceptually, it was similar to whatto protect the pilot against the increasingly the physiological effects of altitude. As aircraft others would ultimately build, but there is nolow atmospheric pressures encountered athigh altitude—pressures that reach essentially became capable of climbing above 30,000 feet, the concern was no longer how to keep the record that Sample ever fabricated his suit.3 That brings the story to the other side of 25zero above about 250,000 feet—and the ter- aviator warm but how to provide him oxygen North America.rible cold encountered at extremely high alti- and protect him from reduced pressure.2tude.1 Years before the involvement of EARLY PRESSURE SUITSlarge Government, academic, and corporate The first known serious concept for a pressureentities, however, comes the story of a couple suit came from Fred M. Sample of Jackson- It seems that Massachusetts has an indelibleof visionaries and the early pioneering work ville, OR. On July 16, 1918, Sample received link to pressure suits. The David Clarkon full-pressure suits. U.S. Patent 1,272,537 for his “Suit for Avia- Company, an entity that will play a remark- tors.” Being a smart inventor, never claiming able role later on, was founded only 50 milesA distant precursor of the full-pressure suit an original item, he instead claimed “certain from where the story nominally begins.was, arguably, the dry suit used by turn-of- new and useful improvements.” In particular,the-century commercial salvage divers, com- he expected the suit could supply oxygen for Four years before David M. Clark foundedplete with their brass helmets and weighted aviators or travelers crossing high mountains. the company that would bear his nameboots. During 1920, renowned Scottish physi- The full suit included a metal (although in Worcester, MA, Mark Edward Ridgeologist Dr. John Scott Haldane (1860–1936) Sample indicated any suitable material could (1906–1962) resided in nearby Dorchester Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby and aspired to do great things. Before he did, balloons, so he decided to use an open basket. clearly described a “stratosphere flying suit”9 however, Ridge would try a meaningless stunt. Although he apparently did not understand developed in collaboration with Priestly. On January 16, 1931, he parachuted out of the physiology behind the concept, Ridge an airplane 2,000 feet above the Charles River. knew he would need to surround his body At the time, Haldane was working with Oddly, at the time, Massachusetts had a law with pressure. Lacking a pressurized gondola, Sir Robert H. Davis10 of Siebe Gorman & prohibiting anybody from jumping out of he concluded a pressure suit would serve the Company to develop improved deep-sea div- an otherwise perfectly good airplane, and the same purpose. Ridge was certain he had hap- ing suits. Siebe Gorman was the preeminent police promptly arrested Ridge, who eventu- pened upon a crucial idea and began search- diving equipment makers of the day, and the ally received a suspended sentence.4 ing for a patron. Repeated correspondence company made a range of different diving with the U.S. Army and U.S. Navy brought helmets that could be identified by the num- Just two days after the court sentenced continued disappointment. Ultimately, at the ber of bolts (6, 8, or 12, depending on the Ridge, on May 27, 1931, Auguste Piccard suggestion of Dr. Timothy Leary,6 the Boston operating depth) used to attach the helmet to (1884–1962), a Swiss professor of physics medical examiner, Ridge contacted Dr. John the collar of the suit.11 Diving suits had gone at the University of Brussels, and his assistant, Scott Haldane, Professor of Metallurgy, Gas- through a revolution during the mid-1800s, Charles Knipfer, reached a record altitude of ses, Liquids, and Respirations at the University much as aviation pressure suits would in the 51,775 feet over Augsburg, Germany, becom- of Oxford, England, seeking assistance.7 1950s. The earliest diving suits were nothing ing the first humans to venture into the strato- more than vests with separate helmets held sphere. Their balloon, designated CH-113, Haldane, along with his son John Burdon in place by just their weight. Many divers26 was little more than a rubberized cotton gasbag with a 7-foot-diameter pressurized gondola that Sanderson “Jack” Haldane (1892–1964), had spent 30 years experimenting with a small drowned because they moved in a way that allowed water to enter the helmet. One diver, Piccard designed to combat the effects of high pressure chamber to determine the reason George Edwards, suggested bolting the helmet altitude. Funded by King Albert’s Fund for behind decompression sickness in deep- to the breastplate of a full suit, making a truly Scientific Research, the pair studied the inten- sea divers. In 1908, Haldane and Dr. John watertight ensemble. Edwards encouraged sity of cosmic rays using a small electroscope. G. Priestly published the first meaningful Augustus Siebe to produce the design, and it About 15 hours after ascending, the balloon decompression tables for divers, which was the start of a long and successful series of settled on the glacier above the village of Ober the Royal Navy subsequently adopted for diving suits from the company.12 Gurgl in the Austrian Tyrol region.5 Ultimately, service.8 In 1911, Haldane led an expedition Piccard made 27 balloon flights, setting a final up Pikes Peak, CO, to study the effects of Less than a month after their initial contact record of 72,177 feet. They were altitudes that low barometric pressure, and he concluded with Ridge, Haldane and Davis had con- airplanes of the day could not touch. that a pressure suit would eventually be structed a hypobaric protection suit by sub- needed by flyers attempting to reach high stantially altering one of their diving suits. Ridge also wanted to set a record. However, altitudes. World War I distracted Haldane, Like the diving suit it was derived from, he believed that pressurized gondolas were who concentrated on the development of Ridge’s garment was made of rubber and can- too heavy to exploit the full performance of oxygen equipment, but in 1922, the professor vas, sewn together into an airtight full coverall Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby helmet covered the head. Ridge left Boston stratosphere. In response, Ridge designed an for London as soon as Haldane confirmed the insulating garment he could wear under the suit was ready. On November 16, 1933, Ridge suit. Along with Samuel Ring, a Boston alu- donned the suit and became, apparently, the minum foil dealer, Ridge made a set of long first human to be tested wearing a pressure underwear made up of 12 alternating layers suit in an altitude chamber. Haldane lowered of aluminum foil and cotton cloth. Gloves, the pressure to a simulated 50,000 feet alti- socks, and a head covering completed the tude (87 mm Hg) and Ridge suffered no ill ensemble. The chamois facemask had three effects. Two weeks later, on November 29, holes: one for each eye and one for the mouth. 1933, Ridge used a suit pressure equivalent to A set of goggles covered the eyes and a primi- approximately 42,000 feet (133 mm Hg) at tive oxygen mask covered the mouth. a chamber pressure equivalent to 83,500 feet (17 mm Hg); the entire test had taken about The Liquid Carbonic Corporation in an hour, with at least a few minutes at the Cambridge, MA, agreed to support a test of the maximum altitude.13 suit, largely to obtain the publicity such a stunt would bring. The company lined a steel tank The London Daily Mail reported the tests, with 1,000 pounds of dry ice, and on March 8, and the British Air Ministry quickly expressed 1934, Ridge entered the tank. Despite carrying interest in the suit. Ridge tried to persuade the Ministry to supply an open-basket balloon for a small tank of breathing oxygen, carbon dioxide gas quickly subdued Ridge. The failure 27 flight tests in the stratosphere, but ultimately was traced to the oxygen mask, which did not the British declined. The denial apparently had seal well. By the time Ridge and Ring could little to do with concerns over possible injuries repair it, Liquid Carbonic had a change of to Ridge, but rather it was based on the likeli- heart and refused to allow a second test. For aAlthough undoubtedly not Mark Ridge’s suit, this example of hood the balloon would drift over Europe and while, Ridge gave up.15a Haldane-Davis full-pressure suit shows that Siebe Gorman that the Haldane-Davis “stratosphere flyingwas certainly on the right track. The suit is tight fitting, and suit” would fall into German hands.14 Two years later, on March 25, 1936, Dr. Karlthe straps on the torso are likely to keep the suit from balloon- T. Compton, renowned physicist and presidenting under pressure. Ridge brought his suit back to the of the Massachusetts Institute of Technology, United States and quickly realized a flaw in wrote a letter endorsing Ridge’s pressure suitNational Archives College Park Collection the tests in London. Although they demon- to Maj. Gen. Oscar Westover, the chief of the strated that the suit provided protection from U.S. Army Air Service.16 Apparently, Ridgewith gloves and boots (minus the lead weights the low pressure at high altitude, the tests had convinced Compton to support his causeused by divers). A modified brass diving not simulated the cold temperatures in the based largely on grossly exaggerated claims of Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby his tests at Siebe Gorman and Liquid Carbonic. age of 14, reportedly, had decided to become a couple of years, Hall decided to sell his air- By this time, Wiley Post had already made his an aviator. It was not as easy as it sounded. plane, and Post went to work as a test pilot for record-attempting flights with an operating His aviation career finally began at age 26 as a Lockheed Aircraft Company in Burbank, CA. pressure suit, and the Army was well aware of parachutist for the Burrell Tibbs & His Texas There, he fell in love with the Vega.21 the technology since Post had tested his suit in Topnotch Fliers flying circus. After making an altitude chamber at Wright Field, OH. The 91 jumps, Post decided the career path did not Designed by John K. “Jack” Northrop and Army researchers were more than willing to test provide sufficient funds to pursue his real pas- Gerard “Jerry” Vultee, both of whom would Ridge’s suit, but Westover overruled them for sion of flying, and he went to work as an oil later form their own aircraft companies, the unknown reasons.17 rigger in Seminole, TX. On his second day of Vega broke ground by using a full monocoque work, October 1, 1926, an accident cost him fuselage and cantilever wings. The laminated Ridge subsequently wrote to Louis A. Johnson, his left eye, but he used the $1,698 settlement wood fuselage skin was manufactured using a the Assistant Secretary of War, and finally to to buy his first aircraft—a wrecked Curtiss large concrete mold, and the fuselage halves President Franklin Delano Roosevelt, neither JN-4 Jenny that he subsequently rebuilt.19 In were then nailed and glued over a previously with any success. Without support from the August 1928, Post applied for a commercial made wooden rib frame. The metal wing was military and unable to raise sufficient financial pilot’s license, which presented the Depart- mounted in a streamlined faring on top of support for the cost of his balloon, Ridge could ment of Commerce with something of a quan- the fuselage and power came from a single not put his suit to actual use. The courts judged dary given the loss of Post’s left eye. The flight 225-horsepower (hp) Wright J-5 Whirlwind him insane in 1942 and Ridge never again surgeon agreed that Post’s depth perception radial engine.2228 saw the outside of an asylum. Mark Edward Ridge died on April 16, 1962, at the age of 56, was better than most people with two eyes, and eventually the Government issued Post a The first Vega 1 made its maiden flight on without realizing his dream of flying into the waiver that allowed him to obtain a commer- July 4, 1927. The airplane spanned 41 feet stratosphere in an open balloon.18 Nevertheless, cial ticket.20 across, was 27.5 feet long, and had a gross he lays claim to having, with the able assistance weight of 4,200 pounds. It could cruise at a of John Scott Haldane and Sir Robert Davis, Post used the Jenny for stunt flying, making then-fast 120 miles per hour (mph) and had conceived and built the first full-pressure suit. a better living than he did as a parachutist. a top speed of 135 mph. However, airlines While performing in Ardmore, OK, Post met quickly decided that a 4-passenger airplane WILEY POST AND THE WINNIE MAE Mae Laine, and later the same day, the couple was not economical, and most of the 68 Vega was married. It did not take long for Post to 1s went to private owners. Despite its commer- Despite the dreams of Ridge and the pioneer- discover that he could not support a wife by cial failings, the airplane was fast: in the ing efforts of Haldane and Davis, American stunt flying. During an air show, Post heard 1928 National Air Races in Cleveland, OH, adventurist Wiley H. Post (1898–1935) that millionaire oilman Florence C. “F.C.” Vegas won every category. In 1929, Lockheed lays claim to being the first to actually use Hall, had recently purchased an airplane and, introduced the Vega 5, which, used the a full-pressure suit. Post was fascinated by despite never having previously met the man, 450-hp Pratt & Whitney R-1340 Wasp engine the Wright Brothers as a child and by the Post wrangled a job as his personal pilot. After and carried six passengers. Equipped with a Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbystreamlined NACA engine cowling, cruise around the world in 8 days, 15 hours, and advantage of the powerful tailwinds hespeed increased to 155 mph and top speed to 51 minutes, earning the pair a ticker-tape believed existed at high altitudes.29165 mph. Unfortunately, its economics were parade in New York City and lunch at thenot much better, and almost all of the 64 Vega White House. Two years later, Post equipped Writing in the 1850s, the pioneering American5s went to private owners as well. Regardless the Winnie Mae with an autopilot and radio balloonist John Wise (1808–1879) theorizedof its perceived failings as an airliner, the Vega compass, then proceeded to fly around the there was a “great river of air which alwaysbecame famous for its use by a number of world solo in 7 days, 18 hours, and 49 min- blows from west to east” that could take hisnow-legendary pilots who were attracted to the utes, earning himself a second ticker-tape balloon across the Atlantic.30 Wise made overrugged and long-range design. Amelia Earhart parade. The Fédération Aéronautique Inter- 450 flights during his lifetime and was respon-used a Vega to become the first woman to fly nationale (FAI) awarded Post the Gold Medal sible for several innovations in balloon design.solo across the Atlantic, and Wiley Post would and the International League of Aviators Unfortunately, Wise mysteriously disappearedfly his around the world, twice.23 (Ligue Internationale des Aviateurs) presented on a trip in high winds from East St. Louis on him with the Harmon Trophy.26 More impor- September 28, 1879, before he had made anyPost’s enthusiasm for the Vega was contagious, tant, perhaps, to Post was an observation he progress in further defining his theory.and Hall agreed to purchase one if Post would made during these flights: the higher you fly,fly it for him. Post agreed, on the condition the faster you go. Based on his observations during his around-that he could enter it in the National Air Race the-world flights, Post was certain that WiseDerby from Los Angeles to Chicago. Hall During 1933, Melbourne, Australia, was was correct and believed that “high winds,”thought it was a good plan. On August 23,1930, the gloss-white Vega with purple cheat preparing to celebrate its centennial in October 1934. To properly mark the event, as he called them, existed in the stratosphere. If he could find these, they could carry the 29lines landed at the Curtis-Reynolds Airport Sir MacPherson Robertson (1859–1945), Winnie Mae at greatly increased speeds. Thesejust north of Chicago after a 9-hour, 9-minute an Australian philanthropist, entrepreneur, winds are now known as the “jetstream.”record flight. Hall was ecstatic and promptly and founder of the Mac Robertson Steamgave Post the $22,000 airplane. It was the Confectionery Works,27 offered a cash prize During the early 1930s, the physiologicalbeginning of worldwide fame for Wiley Post, of £10,000 (about $50,000 at the time, or aspects of long periods at altitude were notand the airplane named Winnie Mae.24 $750,000 today) to the winner of an air race well understood, and neither the engines nor between Mildenhall, England and Melbourne, propellers of the day were capable of propel-In 1929, the German airship Graf Zeppelin Australia, via a designated course over Baghdad, ling a meaningful airplane at high altitudes(LZ127) circumnavigated Earth in 21 days, Allahabad, Singapore, and Darwin.28 It was a for any length of time. There was an ongoing5 hours, and 31 minutes, making a journey race Post could not resist. However, Post was competition, mostly in Europe, to set altitudethat covered 30,831 miles.25 Wiley Post was also well aware that much better aircraft had records, but these were simple up-and-downcertain a fixed-wing aircraft could do the emerged during the 5 years since Winnie Mae flights that provided minimal exposure to thesame trip much faster. With Australian was built. To compensate, Post intended to effects of high-altitude flight. Nobody wasHarold Gatty, Post took the Winnie Mae fly in the thin air above 30,000 feet, taking talking seriously about long-distance flights Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby above 30,000 feet or even 20,000 feet—except requirements, and difficulties, in the develop- The sleeves were carried to the neckline in Wiley Post.31 ment of pressure suits. a raglan cut, and the suit included pigskin gloves and rubber boots. The two-piece gar- Despite his lack of knowledge of the subject, In the spring of 1934, Post asked for assistance ment (shirt and trousers) sealed at the waist Post knew that he needed pressurization to from his friend Jimmy Doolittle, who had using a Duralumin metal belt.34 keep him alive. Oxygen masks of the period joined Shell Oil Company as director of avia- were ineffective at any serious altitude, tion and might have been capable of making At the same time, Lowell Peters, a metal- and physiologists had not yet discovered a pressure suit. Doolittle referred him to the worker in Los Angeles, fabricated an alumi- the concept of pressure breathing. Post Research Aviation Department of the B.F. num helmet for Post. It generally resembled a realized that it was impossible to pressurize Goodrich Company in Los Angeles. Post first welder’s helmet, weighed 3.5 pounds, and had the wooden fuselage of Winnie Mae, and visited the Goodrich plant on April 6, 1934, a 2.75- by 7.5-inch rectangular visor made incorporating a separate pressurized cabin into and requesting, “a rubber suit which will of two layers of clear plastic. A bulge covered the Vega would be prohibitively expensive. enable me to operate and live in an atmosphere each ear to accommodate headphones and Running out of options, Post decided on of approximately twelve pounds absolute Post could eat when the suit was unpressur- the only other course available—he would [5,500 feet altitude equivalent]. I expect to fly ized by opening a small door over the mouth. have to pressurize himself.32 through rarefied areas where the pressure is as Addressing another area that would long vex low as five pounds absolute [27,000 feet]. The designers, front and rear handles on the lower Post’s pressure suit seemingly had no connec- temperature incident will be taken care of by edge of the helmet allowed Post to tie it down30 tion to the efforts of Mark Ridge around the same time, and it is not clear if Post knew heating the air from the supercharger by coil- ing it around the exhaust manifolds.”33 A new to the suit to keep the helmet from rising when the suit was pressurized. The estimated about Fred Sample or John Scott Haldane’s engine supercharger would provide compressed cost of the pressure suit and helmet was $75 theoretical suggestions. In any case, the suit air for suit pressurization and ventilation. (an unbelievable $1,500 in 2009).35 that Post needed was quite different than the one developed by Haldane and Davis. Because Goodrich assigned William R. Hucks as the Goodrich tested the suit by pressurizing it to of its deep-sea roots, the Haldane-Davis suit project engineer for the development of the 5 psi. A major flaw quickly became appar- was stiff, and even simple movements were suit, with John A. Diehl and J. Stevens assist- ent: the pressurized suit would not allow the difficult to perform when the suit was inflated. ing in its fabrication. Progress was agonizingly wearer to raise his arms, which hang uselessly This would not have been a major issue for slow, primarily because none of the Goodrich at his sides. Hucks quickly reworked the arms Ridge since flying an open-basket balloon personnel were familiar with making clothes, of the suit and subsequent tests showed the requires little movement; mostly it involves so Post eventually asked Goodrich to hire a arms could be raised with considerable effort. quietly sitting and waiting. Flying an airplane, professional tailor to make the initial patterns. Some leakage was detected near the waist on the other hand, requires the pilot to move Goodrich fabricated the first suit from 6 yards joint, but it was considered acceptable, so his legs, arms, and fingers almost constantly. of rubberized parachute cloth with two layers Goodrich shipped the suit to Post in Ohio.36 This would become one of the defining glued together on a bias to minimize stretch. Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Wiley Post shows off his inflated full-pressure suit in frontof the Winnie Mae. Note the wingnut on Post’s shoulder,just behind the helmet. The oxygen generator is on theground next to Post, connected to the left side of the visor.The position of Post’s arms shows the relative stiffness of theinflated suit, something that would hamper pressure suitdevelopment for another 50 years.Courtesy of Chevron Corporation ArchivesPost was at Wright Field consulting withthe Engineering Division of the Army AirCorps. In particular, he dealt with the Equip-ment Branch, which was responsible forevaluat-ing flying suits, goggles, and methodsof protecting aircrew against cold. WrightField had an altitude chamber large enough(10 feet high and 9 feet in diameter) for aman, although the Army mostly used it to 31check altimeters. This chamber had origi-nally been installed at the Medical ResearchLaboratory at Hazelhurst Field in Mineola,Long Island, NY. In March 1921, a firedestroyed much of the laboratory, but,fortunately, the chamber survived.37During the 1930s, the Army Air Corps wasan organization in search of an identity.Funding was at an all-time low, and serviceonly had several hundred operationalairplanes, most hopelessly obsolete. WileyPost and his pressure suit seemed the stuffof science fiction when he showed up and
    • asked for assistance in testing the garment. On June 23, 1934, while Post was pressurizing the suit to a differential pressure of 2 psi as a demonstration for the Army engineers, a piece of reinforcing tape failed, effectively ending the effort. Nevertheless, according to a press report in The Cleveland News, Post apparently made at least one flight in the Winnie Mae while wearing the unpressurized suit, most likely to check mobility and vision while wearing the ensemble.38 Post took the damaged suit to the Goodrich plant in Akron, OH, where he met Russell S. Colley (1899–1996), who was intimately familiar with using rubber products in aero- nautical applications. Colley had been born in 1899 in Stoneham, MA. As a young man,32 Colley displayed excellent mechanical skills but told his parents that he wanted to designThe Post pressure suit was women’s clothing. Not agreeing with thisfairly flexible when not career choice, his parents persuaded him topressurized, allowing Post enroll at the Wentworth Institute of Mechani-a reasonable amount of cal Engineering. In 1928, Colley accepted amovement and comfort. position with the B.F. Goodrich CompanyNote the nipple below the as a mechanical engineer and was part ofleft knee where air exited the team that developed de-icing boots forthe suit; normally this was aircraft.39 Goodrich researchers determinedattached to a regulator and that gluing an inflatable rubber “boot” on thepressure gauge. Given that it leading edge of an aircraft’s wing (and empen-was the first real attempt at nage) and alternately inflating and deflatingbuilding a workable pressure it, caused ice to break off. In December 1931,suit, the Post garment Colley and Wesley L. Smith, a former Airworked remarkably well. Mail Service pilot who was then operationsNASA
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbymanager for National Air Transport, used he had been measured for the original suit and Unlike the first two suits, which Post entereda Travel Air 6000 mail plane for a series of Colley had used the same patterns. The only from the waist, an enlarged neck openingflights into known icing conditions to test way to extract Post was to cut the suit into provided entry to the third suit. The newthe Goodrich de-icing boots. Colley sat on an pieces. Nevertheless, Colley and Post learned a helmet bolted to a metal collar after the pilotorange crate in the mail compartment of the great deal concerning the behavior of the suit was securely in the suit. Post could not reachairplane and used a bicycle pump to inflate under static pressure.42 By now it was obvious the wing nuts in the back of the helmet andthe tubes, alternating from one tube to the that Post would not have a suit ready for the required assistance to don and doff the suit.45other by means of a manually operated valve. MacRobertson Race.43In late 1932, William S. “Billy” Brock flew The new helmet was considerably improvedfurther tests using a Goodrich-owned Lock- After the unexpected turn of events with the and included a large round window, made ofheed Vega named Miss Silver Town. By 1934, second suit, in late July 1934, Post and Colley glass instead of plastic, that Post could eas-the Goodrich system was becoming standard decided to fabricate an entirely new suit and ily remove since the faceplate edge had largeequipment on American airliners and many helmet. For the third suit, Colley suggested notches to accommodate gloved fingers. Thelower-speed aircraft still use similar systems two separate layers: an inner, body-contoured helmet was wide enough to accommodate(they are not effective on high-speed aircraft rubber garment that would contain gaseous earphones and did not have the bulges of thethat require precise airfoil shapes).40 oxygen under pressure, and an outer, three-ply first helmet. Oxygen entered through a port cloth garment, made to resist stretching and to just to the left of the window (Post had theMeanwhile, the MacRobertson Race was only hold the rubber suit to Post’s body contours. patch over his left eye) to defog the glass. An3 months away. Colley developed a new suitthat would work with the original helmet, The third suit used a differential pressure of 7.25 psi (0.5 atmosphere), 2 psi greater than outlet to the right of the window vented the helmet. A valve, attached to a regulator and a 33although he installed an oxygen hose fitting the first two suits.44 pressure gauge, just below the left inner kneebelow the visor. Post entered the two-piece controlled outflow from the suit.suit through the waist, and two large metal Colley began by taking precise measurementsplates sealed the torso. Flexible elbow and of Post sitting in a position that mimicked After a detailed evaluation and several staticknee joints allowed improved limb movement what was needed to fly the Winnie Mae. He inflation tests, on August 27, 1934, Post madewhen the suit was inflated.41 made cardboard limb and trunk forms and the first altitude chamber test of a pressure used them to cut the fabric for the outer layer. suit in the United States. As the simulatedIn a turn straight out of a slapstick comedy Colley formed the inner pressure layer by altitude passed 18,000 feet, Post screwed inof the era, the first time Post tried on the new pouring liquid latex over sheet-metal forms. the glass window and the suit began to inflate.suit, he became stuck in it. Partly, this was Thanks to the new set of measurements, this Everybody immediately noticed the helmetbecause of the hot and humid weather that suit fit much better. Since Colley formed began to rise off Post’s head, and Colley notedembraces Dayton in July (and the lack of the suit for the sitting position, Post walked the need for some type of restraint. However,air conditioning in 1934), but it was mostly slightly bent over while wearing it, although the liquid oxygen system was not providingbecause Post had gained several pounds since he could stand straight with some effort. enough oxygen, and after 27 minutes, as the Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John KearbyThe Winnie Mae while it up, Post asked if Parker could interest Phillipswas sponsored by the Pure in sponsoring his flights. Post soon flew theOil Company. The Lockheed Winnie Mae to Bartlesville, OK, to meet withVega was 27.75 feet long, Frank Phillips, sealing a deal.51spanned 41 feet, and hada gross weight of just over Post used his pressure suit on eight or nine4,000 pounds. Lockheed flights at Bartlesville, reportedly reachingdesigned the airplane to 50,000 feet. However, it takes two inde-cruise at 140 mph and fly pendent means to verify a record; in this725 miles at altitudes under case, those sources of verification were two20,000 feet, figures that Post barographs installed in the aft fuselage by theroutinely exceeded. National Aeronautic Association, the U.S. representative to the FAI. Unfortunately, theCourtesy of Chevron National Bureau of Standards reported thatCorporation Archives both barographs failed on all but one flight on which one barograph failed and the other recorded only 38,000 feet after corrections for atmospheric conditions. No record for Post.5234 chamber passed 21,000 feet, Post signaled he during an altitude-record attempt sponsored Despite the setback, Post began to prepare for needed to descend.46 by the Pure Oil Company (now part of Chev- a coast-to-coast stratospheric flight. He flew ron) as part of the Chicago World’s Fair.48 The to Burbank, CA, for one further modifica- Afterward, Colley added bandolier-type cords, flight revealed that the pressure suit worked tion to Winnie Mae: eliminating the landing which were looped around the helmet and well, although some minor adjustments gear to reduce drag. At the Pacific Airmotive attached to a semi-rigid, 8-inch-wide sling would be necessary, including extending the Hangar in Burbank, Jimmy Gerschler and that Post sat on. On August 29, Post reached control stick to allow the inflated glove to the soon-to-be-legendary Clarence L. “Kelly” 23,000 feet during 35 minutes in the chamber better grasp it. The maximum pressure differ- Johnson—another person who would have and by all accounts, was satisfied with the per- ential on the flight was 3 psi.49 a major influence on later events—designed formance of the suit.47 new main landing gear that could be jet- From Chicago, Post called Will D. “Billy” tisoned via a handle in the cockpit. A spruce On the following day, Post took the Winnie Parker, the aviation director for Phillips timber was glued to the fuselage for use as a Mae on the first flight with an operating pres- Petroleum.50 After explaining that the Pure skid during landing, and a strong V-shaped sure suit. On September 5, 1934, Post reported Oil Company and other sources of financing support was placed in front of the lower that he reached 42,000 feet over Chicago for his stratosphere experiments were drying engine cylinders that ran to the lower front Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbyedge of the NACA cowling. Post made five second ending at Wichita, KS, (1,188 miles) On August 15, 1935, just 2 months after hisflights at Burbank, all using the pressure suit on June 15 after a piston burned-through.56 last flight in the stratosphere, Post made hisin preparation for his stratospheric flight.53 Post decided the Winnie Mae was too old and final takeoff, in a bastardized Lockheed Orion- tired for further attempts. He had nonethe- Explorer seaplane in Alaska. The engineTranscontinental and Western Airlines (TWA) less proved the practicality of a pressure suit, stopped at a low altitude, and the ensuingjoined Phillips Petroleum as sponsors of the spending about 30 hours in the stratosphere. crash killed Post and his passenger, humoristflight and arranged for Post to carry airmail, The Winnie Mae approached ground speeds Will Rogers. Post was only 36 years old butincluding special stamps bearing his picture of 340 mph, more than a third faster than the had made an indelible mark on aviation.57and the inscription “First Air Mail Strato- airplane’s normal maximum speed. The Smith-sphere Flight.”54 On February 22, 1935, Post sonian Institution subsequently purchased the INTERNATIONAL EFFORTStook off, but the engine began to leak oil Winnie Mae, which is currently on displayafter only 31 minutes, forcing Post to land at the Udvar-Hazy Center near Washington The 1930s saw considerable internationalon Muroc Dry Lake, later home to Edwards Dulles International Airport in Chantilly, VA. competition to set altitude records, and thisAir Force Base, only 57 miles from Burbank. The helmet from Post’s first suit, and his entire spurred the development of several pressureSince Post could not doff his pressure suit hel- third suit, are also in the collection of the suits. It should be noted that almost all ofmet by himself, he walked about 400 yards to National Air and Space Museum. these were simple up-and-down flights thatask H.E. Mertz for assistance; Mertz promptlyfainted. A few days later, Post announced thatit was not a broken oil line that had foiled hisflight, but rather emery dust that mechanics 35found in his engine. Someone had deliberatelysabotaged the flight.55After repairs, Post tried again. On March 5, Wiley Post peers over thehe got as far as Cleveland before his oxygen top of the Winnie Maeran out. After climbing out of the airplane and while wearing his pressureremoving the pressure suit, Post learned that suit. Given it was the firsthe had flown 2,035 miles in the record time of of its type to be used opera-7 hours and 19 minutes. The Winnie Mae had tionally, the Russell Colley-averaged a ground speed of 279 mph, approxi- designed garment workedmately 100 mph faster than she should have remarkably well.flown. Two more flights followed, the first end-ing at Lafayette, IN, (1,760 miles) on April 14, Courtesy of Lockheedafter the external supercharger failed, and the Martin Aeronautics Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Post tried numerous times extended chord wings and a superchargedto set an altitude record, engine driving a four-blade propeller.but it was just not to be. However, Pezzi did not use a pressure suitDespite his failure at this one on this flight since the Ca.161bis had aendeavor, Post remains one pressurized cockpit.60of the early aviation legends. In France, Dr. Paul Garsaux developed a suitCourtesy of Chevron during the mid-1930s with the backing ofCorporation Archives the Potez Airplane Company. Garsaux was a pioneer of aviation medicine in France and director of the Paul Bert Aeromedical Center at Le Bourget. During World War I, Garsaux developed an aviation oxygen system that used an aluminum mask shaped to conform to spent little time at high altitude and did not several layers of canvas and rubber, with a the wearer’s face, with inflatable face-sealing put the same stress on aircraft, pressure suits, metal collar that attached to a cylindrical bladders to ensure a tight seal. The mask had or pilots as does cruising in the stratosphere. metal helmet with square viewing ports. a built-in heating system to avoid the exhaled In addition to the Americans and British, the The electrically heated suit used metal alloy water vapor turning to ice.6136 French, Germans, Italians, Russians, and Span- ish developed high-altitude pressure garments, restraint devices, including a breastplate, to prevent the fabric from ballooning. In The first Garsaux suit, codeveloped with all of which would later be called full-pressure 1934, Baronessa Carina Negroni reportedly Dr. Rosenstiel from the French Navy, suits. There were many objectionable features wore the suit to climb to 50,583 feet, used two layers of linen, but this proved to these early suits since they prevented evapo- undoubtedly becoming the first woman to unsatisfactory and was soon replaced by ration of perspiration, greatly restricted mobil- use a pressure suit. Despite several reports laminated layers of silk and rubber doped ity when pressurized, and were heavy and that the Italians, including Negroni, used the with acetone to make it airtight. Large bulky.58 Nevertheless, they worked, mostly. suit to set records in the mid-1930s, the FAI shoulder joints allowed arm movement and database does not reflect this. It is likely that a set of gloves was spring-loaded into a The Italians developed a suit in 1933 to the reported flights took place but were not closed-fist position. A round Duralumin allow Regia Aeronautica pilots to set altitude recognized by the FAI for various reasons.59 helmet had rectangular eye openings made records using several specially built open Ultimately, Italian Col. Mario Pezzi took the of two layers of glass with an air space in cockpit Caproni Ca.161 airplanes. These were altitude record from the British on October between them to prevent fogging, although conventional biplanes based on the Ca.113 22, 1938, when he climbed to 56,046 feet the mask also had an electric defogging with staggered wings of equal span. The suit, above Guidonia Montecelio, Italy. He used system. At only 31 pounds, the French suit designed by Capt. Cavallotti, was made of a modified Caproni Ca.161bis that had was lighter than the one used by Wiley Post.62 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John KearbyGarsaux demonstrated the suit at Le Bour- tall and permit “rapid dressing and undressing this severely restricted mobility and ultimatelyget in June 1935. Most likely, Marie-Louise without additional help.”66 The suit needed to proved unsatisfactory.68“Maryse” Hilsz wore the suit when she set the allow free movement of the arms, legs, and fin-female altitude record of 46,949 feet on June gers to permit the pilot to fly the aircraft and One of the most difficult requirements faced23, 1936, flying a Potez 506 over Villacoublay, provide the possibility of parachute escape. by Dräger, and all future pressure suit devel-France. The climb took 36 minutes in the Electric heaters would protect against the cold opers, was how to provide sufficient mobility770-hp biplane. Similarly, Georges Détré likely at high altitude and prevent fogging of the at the joints. Dräger started with a tube withused the suit when he climbed to 48,698 feet visor. Dräger calculated that the required test longitudinal folds held in place with one longi-over Paris in a Potez 506 on August 14, 1936, pressure of 35.3 psi necessitated the use of a tudinal band. This provided, under pressure, aalthough no documentation was available to heavy material that “cannot readily be formed tube that was flexible in one plane, but it pro-confirm he used the suit.63 Unfortunately, all of into a garment.”67 Nevertheless, the company vided insufficient mobility. A careful analysisGarsaux’ work and records were destroyed by produced a series of “hard suits” that looked of pilot movements in the cockpit of large air-German bombs on June 3,1940, and by Octo- much like medieval suits of armor. craft showed that the arms did not need a fullber all further aeromedical research in France range of movements; only the forearms neededhad been halted by the Nazi occupiers.64 Based on revised, relaxed requirements, the first to move enough to manipulate the control Dräger full-pressure suit used laminated layers wheel and throttles. This led to the develop-As might be expected, the Germans were not of natural silk cloth and rubber strengthened ment of airtight ball-bearing socket joints usedidle. In 1935, Dräger-Werke AG in Lübeck, by an external layer of silk fishnet cord that was at the shoulders, biceps, elbows, and wrists.Germany, began developing a hard-shell, full-pressure suit for the German Air Ministry. supposed to control the fabric’s tendency to balloon under pressure. The helmet, made of By 1942, Dräger was concentrating on alu- minum hard suit designs pressurized at 11 psi 37Dräger was familiar with technologies that the same material, was integral to the suit, but that still offered satisfactory mobility. In Juneinvolved pressure, including beer-tap systems under pressure the ballooning fabric pressed 1942, Dräger demonstrated a hard suit to thethat used compressed carbon dioxide, medici- the visor painfully against the pilot’s forehead. Air Ministry; it was unacceptably heavy, diffi-nal compressed-oxygen systems, anesthesia Despite the silk cord, the entire suit ballooned cult to walk in, and never became operational.69machines, and aviation-oxygen systems. Per- unacceptably, so the engineers replaced the silkhaps most famously, the company produced fishnet with steel wire and reduced the inter- In the meantime, on October 28, 1941, thethe Dräger underwater breathing apparatus nal pressure to 4.4 psi (0.3 atmosphere). This Air Ministry ordered Dräger to develop anused by the Germans during World War II.65 helped somewhat, but the wire presented a emergency descent suit. Unlike all earlier safety hazard by catching on any protuberance full-pressure suits designed to be the onlyThe requirements levied by the Air Ministry in the cockpit. In addition, the suit elongated protection for a pilot in an unpressurizedincluded being able to operate at an internal (head to feet) to the point that the pilot could cockpit, the get-me-down suit provided onlypressure of 11.8 psi (0.8 atmosphere) with a no longer see out of the visor. Eventually, the short-term protection when an otherwise pres-“three-fold safety factor.” The ministry wanted idea evolved to using chainmail mesh, allow- surized cockpit suddenly depressurized. If thea suit that would fit a pilot 5 feet, 10 inches ing a pressure of 11 psi (0.75 atmosphere), but cockpit suddenly depressurized as the result Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby These oft-published photos38 of the Dräger hard suit show that it was completely impractical as an aviation garment. Note the unusual gloves, where the thumb and forefinger are separate but the remaining fingers are grouped as in a mitten. The concept of a satisfactory hard suit has still not been realized, although NASA continues to experiment with them as exploration suits for journeys to the Moon or Mars. National Archives College Park Collection Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbyof battle damage or equipment failure, the This Dräger Model 8 get-me-down suit was possibly thesuit would quickly inflate to 2.2 psi to protect most developed of the German suits. Note the large, clearthe crewmember long enough to descend to a plexiglass helmet. The pilot is not wearing his oxygen mask insurvivable altitude. The crewmember wore an this photo, but the shape of the helmet was partly dictated byordinary oxygen mask inside a cloth helmet, needing to allow the pilot to move his head side to side withinand air from an engine-mounted compressor the helmet while wearing the mask. Pleats at the elbows andpressurized the suit when required. Ultimately, knees provided at least some measure of flexibility when thethis helmet proved unsatisfactory and the Ger- suit was pressurized.mans eventually settled on a completely clearplexiglass70 dome helmet, but this new helmet National Archives College Park Collectionstill used a separate oxygen mask inside it.71 with pressurized cabins. The pilot was to fly inThe Luftwaffe experimental station (Erpro- a prone position, and the Institute indicatedbungsstelle) at Rechlin, Germany, tested a that freedom of movement under the 3.1-psiseries of get-me-down models, but a flaw in operating pressure was not a concern.73 There isthe original logic quickly became apparent. no evidence that this suit was ever completed.Initially, the Luftwaffe viewed the suit as amethod of keeping the crew alive after cabin In Spain, Col. Don Emilio Herrera Linarespressure failed without regard of who wouldactually be flying the airplane. Unfortunately, built a full-pressure suit in anticipation of an open-basket balloon stratospheric flight 39the initial suits, when inflated, offered almost scheduled for early 1936. Unfortunately, theno mobility. This led to the development of Spanish Civil War intervened. Herrera choseball-bearing joints, similar to those devel- the Republican side and cannibalized theoped for the heavy hard suit, at the shoulder, rubberized silk suit to make rain ponchos forelbows, and wrists. The final suit was made of Republican troops. In 1939, Herrera fled torubberized silk and was entered through an France, where he died in exile in 1967.74enlarged neck opening, although work contin-ued on a two-piece suit that was entered at the The Herrera suit used an inner airtight gar- according to its inventor, although thiswaist. Again, there is no evidence that the get- ment covered by a pleated metallic frame was most certainly an overstatement basedme-down suit entered production.72 with articulating joints for the shoulders, on experience with later suits. The helmet hips, elbows, knees, and fingers. When tested faceplate had three heated glass layers: oneOddly, in the summer of 1944, the German at the Cuatro Vientos Experimental Station, unbreakable, another with an ultraviolet filter,Glider Research Institute ordered Dräger to near Madrid, the suit’s pressurized mobility and the outer one opaque to infrared. Initially,develop a rescue suit for use in gliders equipped was found to be “thoroughly satisfactory” based on the cold atmosphere present at high Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby altitudes, Herrera included an electric heater After World War II, the U.S. in the suit. However, when Herrera tested the Army Air Forces issued a suit in an altitude chamber, he noticed that “Translation of a Report on even at an ambient temperature of –110 ºF, Development of a Pressure the temperature inside the suit climbed rap- Suit” that contained this idly to 90 ºF. A trained engineer, he soon real- diagram of “the final model ized that the task was not to warm the suit but German pressure suit.” The rather to remove body heat by some method. suit is obviously a soft-suit Herrera called his stratospheric suit an esca- but does not precisely match fandra estratonautica. Unfortunately, mostly the description of any because of the urgencies of war, the suit was specific suit in the report. never used in an airplane or a balloon.75 Courtesy of the David Clark When declining to help Mark Ridge, the Company, Inc. British Air Ministry concerns centered on the indeterminate flight paths of balloons, not on the Haldane-Davis suit itself. After Ridge returned to the United States, Dr. Gerald40 Struan Marshall, consultant and applied physiologist for the Royal Air Force, worked with Siebe Gorman to continue development, resulting in the procurement of several proto- type suits. These two-piece garments used rubberized fabric fastened together with a metal and rubber belt at the waist. Instead of a metal helmet like Ridge and Post used, Siebe Gorman used a simple rubber fabric cover with a curved visor made of two layers of Celastoid. Pure oxygen pressurized the suit to a maximum 2.5-psi differential through a flexible tube attached to the right side of the faceplate. Exhaled air exited the left side of the faceplate into a chemical canister that dried the air and removed the CO2.76 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John KearbySquadron Leader F.D.R. “Ferdie” Swain77 used War Department was aware of the need to Ferdie Swain used a laterone of these suits to take a Bristol 138a to an improve the fitness and efficiency of military Siebe Gorman suit toaltitude of 49,944 feet over Farnborough on aviators to carry out combat operations. In capture the world’s altitudeSeptember 28, 1936. The Bristol was an exper- 1917, a Medical Research Board was chartered record in 1936. The lineageimental all-wood monoplane intended specifi- to investigate all conditions that affected the of the suit to the early workcally to capture the world’s altitude record. A efficiency of pilots, determine the ability of of Haldane-Davis is obvious.43,000-foot oxygen-equivalent altitude was pilots to fly at high altitudes, develop suitable Although the suit seemed tomaintained in Swain’s suit because greater apparatus for the supply of oxygen to pilots at perform satisfactorily for thepressures reduced mobility and comfort to an high altitudes, and consider all matters relat- short up-and-down altitudeintolerable degree. The suit performed satis- ing to the physical fitness of pilots. This led to flights, it severely restrictedfactorily, although Swain complained of some the establishment of the Army Signal Corps movement and was generallydiscomfort as the suit inflated and he found it Medical Research Laboratory on January 18, uncomfortable.difficult to move his arms and legs. However, 1918, at Hazelhurst Field on the outskirts ofas the pilot began to descend after his record Mineola, NY. The laboratory’s research scien- National Archivesflight, the faceplate began to fog over and he tists initially focused on developing pilot selec- College Park Collectionfound it difficult to breathe. Unable to unzip tion standards and understanding the effects that reached 28,820 feet before descendinghis suit, Swain had to slice open his visor with on humans of exposure to high altitude. after all three occupants lost consciousness.a knife as he descended through 14,000 feet.78 Although Bert had warned the men about theDespite the problem, the FAI ratified thisflight as a world record.79 On June 30, 1937, Already, aeromedical scientists were well aware that the lack of oxygen (hypoxia) was the necessity of using supplemental oxygen at alti- tude, they apparently failed to heed the advice, 41Flight Lieutenant Maurice James Adam wore pivotal hazard encountered during flight. The and Croce-Spinelli and Sivel asphyxiated,a modified suit to set a record of 53,937 feet effects of hypoxia had been investigated by marking the first reported casualties due toin the Bristol 138a. On this flight, the canopy Dr. Paul Bert (1833–1886), a French zoolo- hypoxia. Tissandier survived to tell the tale.81failed and the Haldane-Davis pressure suit gist, physiologist, and politician, who carriedlikely saved the pilot’s life.80 out 670 separate experiments from 1870 to During World War I, combat pilots found 1878 dealing with the physiologic effects of it necessary to fly above 15,000 feet to avoidAEROMEDICAL PIONEERS altered atmospheric pressure. In 1874, Bert ground fire and soon began reporting symp- subjected two balloonists, Joseph-Eustache toms including headache, loss of muscleShortly after the first powered flight in 1903, Croce-Spinelli and Henri-Theodore Sivel, to strength, dizziness, and fatigue. In addition,scientific interest in the medical aspects of a chamber altitude of 23,000 feet to investi- cases of unexplained losses of aircraft began toflight grew dramatically. It quickly became gate the use of oxygen to prevent hypoxia. On accumulate. Physiologists soon recognized theobvious that the aviation environment was April 15, 1875, Gaston Tissandier, a French root cause as a lack of oxygen and the Armyvery different from the environment on the chemist, meteorologist, and aviator, joined Air Service mounted a major effort to developground. On the cusp of World War I, the Sivel and Croce-Spinelli on a balloon flight the “Clark-Dreyer Oxygen System,” consisting Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby of an automatic regulator and a leather and and proved to be an ideal home for the new temperatures, Armstrong suffered severe frost- rubber mask, in 1918. However, the war School of Aviation Medicine. Four years later, bite, his goggles frosted over, and he did not ended before the new oxygen system was actu- in the summer of 1926, following the rapid have an oxygen mask. Following his return ally installed in more than a small fraction of postwar drawdown of the Air Service, the War to Selfridge, Armstrong thought about the Army combat aircraft. Department moved the School of Aviation obvious physiologic threat to combat effec- Medicine to Brooks Field, TX, to collocate it tiveness and wrote a letter to the Air Surgeon Shortly before the end of the war, a young with the flight training program at that base. in Washington. He concluded his letter with chemical engineer, Lt. Harold Pierce, joined The school’s research program was redirected a strong recommendation that the Air Corps the Medical Research Laboratory after com- to focus on understanding the practical Research and Development Center at Wright pleting a physiology teaching fellowship at requirements for the selection and care of Field address the deficiencies in protective fly- Harvard University. In 1919, he designed pilots. The “Mineola Chamber” was declared ing equipment immediately. Sometimes you a second-generation altitude chamber fab- surplus and subsequently shipped to the need to be careful what you ask for. As a result ricated by the Lancaster Iron Works. The Equipment Laboratory at Wright Field, OH. of his letter, Armstrong was transferred to the chamber, insulated with cork and equipped Closing the chamber was based on the school Equipment Laboratory of the Engineering with a refrigeration unit, enabled researchers commander’s annual report that declared, Section at Wright Field to serve as an aero- to study human response to combined cold “There is reason to believe that the facts of medical advisor. stress, reduced atmospheric pressure, and oxy- physiology which have been so extensively gen starvation that occur at altitude. During investigated during the past six years are far In 1935, now-Capt. Harry Armstrong estab-42 unmanned tests, the chamber reached an alti- tude of 75,000 feet at a temperature of −31 ºF. in advance of the immediate requirements for the Air Service.” This conclusion, of course, lished the Physiological Research Unit as part of the Equipment Laboratory. He discovered Using this facility, researchers at Hazelhurst proved to be false.82 the “Mineola Chamber” sitting idle, covered built the foundation for modern protective with dust in a storage room in the basement. flying equipment. In the fall of 1929, Harry George Armstrong Armstrong had the chamber refurbished and graduated from the School of Aviation used it for 2 years to conduct research on the In November 1919, the Medical Research Medicine and decided his future lay in mili- physiologic effects of altitude. During this Laboratory moved to nearby Mitchel Field tary aviation. During his first assignment as period, the Air Corps began developing the and was subsequently renamed the School of the flight surgeon for the First Pursuit Group long-range bombardment aircraft that rede- Aviation Medicine on November 18, 1922. at Selfridge Field, MI, Armstrong discov- fined the meaning of extreme environments. Mitchel Field was named in honor of a former ered how inadequate the equipment used by The Equipment Laboratory was assigned New York City mayor, John Purroy Mitchel, pilots was. While flying in an open-cockpit responsibility for development of a sealed who was killed while training for the Air Berliner-Joyce P-16 from Minneapolis to pressure cabin for high-flying bombers. Service in Louisiana. Before the War ended, Chicago in late 1934, Armstrong discovered Armstrong was tasked to define the physi- Mitchel Field served as a major training his flight clothing provided little protection ologic requirements for a pressurized cabin.83 base for the rapidly expanding Air Service against the elements. Exposed to −40 ºF air Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John KearbyTo meet this challenge, Armstrong recruited • Reduced atmospheric pressure effects its own on Wright Field, and Benson orga-several talented scientists, including J. William on the middle ear, nasal sinuses, and nized a research program for the laboratory“Bill” Heim, who was about to complete dental fillings; that persisted throughout World War II. Hepostgraduate training in physiology at Harvard staffed the laboratory with nationally knownUniversity. Heim accepted Armstrong’s • Explosive decompression; scientists, drawing significantly upon theinvitation and remained at Wright Field for contacts that he had developed earlier in hismore than 31 years. Armstrong and Heim • The risk of gas bubbles forming in the training at the Mayo Clinic and Harvarddefined the requirements for the pressurized body and prebreathing requirements; University. In collaboration with the Mayocabin demonstrated in the Lockheed XC-35 Clinic, he established a human centrifugeduring 1937. • High-altitude flight stresses, including program to evaluate G-suits and the effects of cold exposure, loss of body fluids, and acceleration on pilots. Prior to World War II,Armstrong was among the first to recognize flying fatigue; Benson recognized the need for a radicallythat in addition to the effects of altitude, different method of supplying oxygen topilots were becoming exposed to increased • Acceleration effects on blood pressure aircrews at high altitude and led the develop-g-forces during aerial maneuvers. In response, and vision; ment of the diluter demand oxygen system.85he designed the first human centrifuge in theUnited States. Though unsophisticated by • Vertigo, airsickness, and spatial disorienta- THE U.S. ARMY REDISCOVERS THEmodern standards, the Balloon Hangar centri- tion; and PRESSURE SUITfuge, fabricated by the Equipment Laboratorymachine shops, allowed Armstrong to study • Toxic hazards in the cockpit, including car- Despite having tested Wiley Post’s full-pressure 43the effects of accelerative forces on blood pres- bon monoxide and radioactive materials. suit in 1934, the Army Air Corps was late tosure, first using goats, and finally humans. start the development of its own suit. It was Armstrong understood the human element not until October 10, 1939 that the ArmyArmstrong’s research encompassed virtually all was an important factor in aircraft design; yet tasked three companies—B.F. Goodrich,aspects of aerospace medicine, and many of engineers of his time paid little attention to Goodyear Tire & Rubber, and United Stateshis investigations were the first of their kind the pilot. Another young physician, Dr. Otis Rubber—to investigate the concept of a full-to be carried out anywhere in the world. An O. Benson, Jr., (then a captain) became the pressure suit for crews of future high-altitudeabbreviated list of the aeromedical problems second chief of the laboratory. Under his direc- aircraft. Based on these initial studies, dur-he investigated during his 6 years as director tion, the Aeromedical Research Unit separated ing the latter part of 1940, the Army issuedof the laboratory include the following:84 from the Equipment Laboratory and formed contracts to B.F. Goodrich and U.S. Rubber three units of its own (Physiological, Biophys- for the development of experimental pressure• Hypoxia and requirements for supplemental ics, and Clinical Research). The newly named suits. For the most part, the early pressure suit oxygen; Aero Medical Laboratory was moved from its contracts ran concurrently with the develop- overcrowded quarters into a new building of ment of the G-suit, although they seldom Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby involved the same companies. Captain John Laboratory in the spring of 1941. This was a for 10 minutes without serious leakage. The G. Kearby of the Equipment Laboratory at two-piece garment made of rubberized fabric Army thought, however, that the neck joint Wright Field was the project officer for the that used a large transparent plexiglass helmet. was overly complicated and that the suit was pressure suit contracts.86 Unlike later suits, this model was pressurized difficult to don and doff.89 using oxygen and a separate oxygen mask was The requirements levied by the Army on both not required. The oxygen hose attached to The U.S. Rubber contract, W535-ac-18048 companies included completely enclosing the the helmet ring directly in front of the face, of December 19, 1940, covered the fabrica- aviator, using fabric that could withstand pres- perhaps not the ideal location. The tight fit- tion of a single pressure suit at a cost of $500 sure and oxidation effects, and delivering a ting suit had metal arms and articulated metal and one G-suit for $142. The low price and prototype suit within 120 days. Other require- elbow joints that resembled a medieval suit 30-day delivery schedule were the result of ments, ones that would continue to prove of armor. Surprisingly, according to Colley the suits having been developed by research- difficult for decades, included permitting the these elbow joints did not leak. The body ers at Wright Field; U.S. Rubber was simply “proper articulation of the limbs and waist” and legs had multiple straps between various fabricating them. The 80-pound Type 1 pres- and using a transparent helmet “to permit the locations to control ballooning. During initial sure suit used rubberized fabric with a lace-up full visibility range.”87 At first, the Army used testing, the suit was pressurized to 2.5 psi front closure and a large transparent plexiglass a sequential “Type” number for the pressure suits. Somewhat later, it adopted an “XH” designation (presumably for “Experimental, Table 3—1943 U.S. Army Pressure Suite Designations44 High altitude”). There was no correspondence between the “Type” designators and the later Original “Type” Designations Later “XH” Designations “XH” designators. Type 1 U.S. Rubber XH-1 B.F. Goodrich Type 2 U.S. Rubber XH-2 U.S. Rubber The B.F. Goodrich contract, W535-ac-17000 Type 3 B.F. Goodrich “Strato-Suit” XH-3 Goodyear of November 29, 1940, covered the fabrica- tion of one high-altitude pressure suit at a cost Type 4 U.S. Rubber XH-4 U.S. Rubber of $6,100. A contract amendment in February Type 5 B.F. Goodrich “Strato-Suit” XH-5 B.F. Goodrich 1941 added a second pressure suit of a slightly Type 6 B.F. Goodrich “Strato-Suit” XH-6 B.F. Goodrich revised design. Goodrich had an advantage Type 7 National Carbon Company XH-7 National Carbonic over the other contractors: its project lead, Russell Colley, had already developed a work- Type 8 B.F. Goodrich XH-8 Unknown able full-pressure suit for Wiley Post.88 Type 9 Goodyear XH-9 Goodyear The designation systems were separate and reflected different pressure suits Goodrich delivered the first Type 3 suit, called (i.e., the Type 1 was not the same as the XH-1). a “Strato-Suit” by Colley, to the Aero Medical Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbyhelmet. Three assistants were required to tore and U.S. Rubber switched its efforts to British claims, the Royal Air Force (RAF)dress the wearer. The original rubber mittens the Type 2. This revised suit was generally had not conducted operational flights aboveproved difficult to use, so U.S. Rubber manu- similar to the Type 1A, except it used a zip- 35,000 feet until 2 months prior to the surveyfactured a steel manipulating device, eerily per front closure and rubber gloves. Since the and did not routinely fly at such altitudes.similar to the one used a quarter century later basic suit was little changed, it too went rigid Nevertheless, Armstrong endorsed theby the robot on the Lost in Space television when pressurized. Despite a relatively poor development of a pressure suit.94series, for the left arm only, as an alternative. showing, U.S. Rubber had substantially sim-Elaborate rubber accordion bellows were plified the Type 2 suit and reduced its bulki- When the Army began testing a revisedlocated at the elbows and knees to provide ness and leakage.92 Goodrich pressure suit at Wright Field, itflexibility under pressure.90 found the new garment considerably improved Shortly after the initial batch of suits arrived over the initial suit. After approximatelyTesting the U.S. Rubber suit at the Aero Medi- at Wright Field, the British Air Commission 10 minutes with the suit pressurized to 2.5 psi,cal Laboratory disclosed numerous deficien- requested information concerning the Army researchers noted that the overall com-cies, including excessive expansion, leakage, American pressure suits. The Materiel Division fort and freedom of motion were fair andand severe discomfort when the suit was pres- wrote a special report for the commission that the normal movements required to flysurized. But perhaps the most critical problem, including the latest details of the Goodrich an airplane were possible with some effort.and the one that would prove most vexing to and U.S. Rubber suits, and in February 1942 The researchers also reported that the suit wascorrect, was that at 3 psi the suit became so provided an unidentified pressure suit to the much easier to don and doff than previousrigid that the wearer could barely move. TheArmy amended the contract on February 18, Royal Aircraft Establishment at Farnborough.93 garments. Joint articulation, particularly of the fingers, was possible even at 3 psi inflation.95 451941, to cover the addition of a single Type 1A In a May 3, 1941, memo, Maj. Gen. Henrypressure suit at the cost of $4,210 and a single H. “Hap” Arnold, the acting chief of staff for These tests seemed to indicate that aType 1G G-suit for $142, both for immediate air, informed Lt. Gen. George H. Brett, the satisfactory high-altitude pressure suit wasdelivery. Although the Army tested the two Chief of the Air Corps, that the British were attainable, and the Army awarded Goodrichtypes of suits independently, the goal was to already routinely flying above 35,000 feet a new contract (W535-ac-21580) ondiscover the best features of both and eventu- using supercharged engines in their fighters. September 25, 1941, for two Type 5 suits.ally to combine them into a single garment.91 Arnold believed it was essential that the The first suit cost $6,500 while the second United States be prepared to fly at these cost an additional $7,500. The Army wantedAs had the original Type G, the Type 1G altitudes without using pressurized cabins, the first suit delivered within 90 days andG-suit proved essentially worthless, and the essentially meaning that pressure suits would the second within 180 days. These suits wereArmy did not pursue the design further, be mandatory. To emphasize his point, Arnold made of rubberized fabric and used fabricexplaining why U.S. Rubber is not mentioned commissioned a survey by now-Maj. Harry bellows-type elbow joints braced with thinin the G-suit chapter. When the Army tested Armstrong of high-altitude operations in steel rods. There was a steel brace across thethe Type 1A pressure suit, an adjustment strap England. Armstrong discovered that, despite front of the chest that connected to shoulder Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby rings that supported the arms. Colley to Wright Field to coordinate the development Akerman was friends with Dr. Walter M. intended this arrangement, incorporated of a suitable pressure suit and of familiarizing Boothby at the Mayo Clinic and spent a into many later Goodrich suits, to control them with the problems involved.97 considerable amount of time working with ballooning. The pressurization hose, electrical the Mayo researchers, only 81 miles away in wires, and radio connections attached to the Sometime in late 1941, the aircraft companies Rochester, MN. Ultimately, between late 1941 left side of the abdomen. Testing showed this decided to take things into their own hands, and the middle of 1943, Akerman would lead suit offered relatively decent mobility and did at least to some extent. Bell and Boeing joined the development of a series of at least nine not suffer from any significant deficiencies.96 with the Strato Equipment Company of pressure suits that he designated BABM for Minneapolis, MN, to develop a pressure suit. Boeing, Akerman, Bell, and Mayo. During 1941, several American aircraft John D. Akerman (1897–1972) had founded companies expressed interest in developing the company to develop oxygen equipment for Akerman designed the BABM suits to oper- their own pressure suits. For instance, high-altitude flight, as well as iron lungs for ate at 1.5 psi, meaning a pilot at 50,000 feet Bell Aircraft submitted a $12,695 proposal patients with respiratory paralysis. Akerman altitude would feel like he was at 37,000 feet. to the Army to fabricate a single pressure had an interesting biography, graduating in This was a much lower pressure than the suit, reportedly for use in a high-altitude 1916 from the Aeronautical School of the typical 2.5–3.0 psi used by other suits. All version of the Bell P-39D Airacobra. During Imperial Technical Institute in Moscow, of these tight fitting suits used double-layer an inspection tour, Boeing chief test pilot studying under professor Nikolai Yegorovich construction so that a tear in one layer would Edmund T. “Eddie” Allen approached Zhukovsky, and enlisting in the Engineering not render the suit useless. Pilots wore the suit46 Maj. John W. Sessums, Jr., the assistant technical executive at Materiel Division, Corps of the Russian Army’s air service branch. He immigrated to the United over regulation underwear and under their flying clothes. Six different valves were used to about having a Seattle company build States in 1918 and graduated from the pressurize each suit, including ones that pro- a prototype pressure suit and charging University of Michigan in 1925 with a B.S. vided ventilation air for the head, hands, and the estimated $5,000 cost to the B-17F in aeronautical engineering. Akerman worked feet. Unsurprisingly, given the Bell and Boeing production contract. Allen indicated that with the Ford Stout Airplane Company connections, various versions of the suit were if the suit proved successful, Boeing would and Hamilton Metal Plane Company and optimized for use in the P-39 Airacobra and purchase at least 10 of them to protect its advanced to Chief Engineer of the Mohawk B-17 Flying Fortress. For instance, the model pilots during flight tests. Sessums knew the Aircraft Corporation. In 1929, he joined the designed for use in the B-17 had a helmet that problem of pressurizing the aircrew would University of Minnesota and founded the could be removed from the front of the face eventually confront all manufacturers of Department of Aeronautical Engineering. rather than over the head, simplifying don- combat airplanes equipped with turbocharged For the next 20 years, Akerman worked with ning and doffing with a low overhead.99 engines and high service ceilings. Although many aircraft manufacturers and was the Sessums declined to allow Boeing to develop Dean of Faculty of Aeronautical Engineering During the week of January 12, 1942, repre- a pressure suit, he commented on the at the University of Minnesota from 1931 sentatives from the Army, Boeing, the Mayo desirability of inviting engineers and pilots until 1959.98 Clinic, and the University of Minnesota held Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbya series of conferences in Seattle to discuss high as 4 psi. Ward T. Van Orman, a champion around to acquaint himself with the limitationsoxygen equipment. Boeing disclosed that it balloon racer, headed the development effort. of the suit and then climbed into the pilot’shad contracted, using company monies, with Goodyear estimated that production suits seat. Compressed air and oxygen were suppliedAkerman to develop the pressure suit that the would cost just $200, versus $1,000 for the through long hoses from supplies outside theArmy had declined to fund the previous year. other suits under consideration.102 airplane. Reed went through all the motionsBoeing acquired Akerman’s services to fur- necessary to fly a mission and had major com-ther its understanding of high-altitude flight For 5 days beginning on January 16, 1942, plaints about only three things: he could notin anticipation of improved models of the Bell test pilot Mervin E. Erickson wore the reach the landing light switches, could not seeB-17 and the upcoming B-29. Akerman had third BABM suit, logically called BABM-3, the dials on one of the radios on the ceiling,already developed, fabricated, and tested sev- in the newly opened Strato-Lab environ- and had great difficulty seeing instruments oneral suits. However, despite progress with the mental chamber at Boeing Plant 1 in Seattle. the lower edge of the panel near his knees.105suits, Boeing cancelled scheduled flight tests Dr. Walter M. Boothby and Dr. William J.using a B-17E because the company did not Randolph “Randy” Lovelace II had already On January 20, 1942, the Army orderedbelieve they had sufficient understanding of evaluated the chamber and pronounced it 10 Type 6 Goodrich suits, generally similarthe underlying physiology. At the time of the ready for operation. The chamber had a to the earlier pair of Type 5 garments, forconference, the BABM suits were cumbersome 108,000 British thermal unit (Btu) refrigera- $34,500. A month later, the Army placedto don and doff, it was nearly impossible to tion unit capable of producing temperatures another order, this time for six Type 6A suits.bend at the waist when the suits were inflated, less than −100 ºF.103 Erickson spent 60 min- All of these suits had a pressurization hoseand the helmets were uncomfortable to wearfor long periods.100 utes in the chamber at temperatures ranging from −57 to −61 ºF accompanied by two and electrical connection in the middle of the abdomen. A further modification, the Type 6B, 47 Boeing technicians wearing electrically heated incorporated a conduit that contained the oxy-In a January 12, 1942, letter, Goodyear also flying suits. Neither the air used to compress gen hose as well as the electrical and radio con-expressed interest in manufacturing high- the pressure suit nor the breathing oxygen was nectors. The conduit attached to the left sidealtitude pressure suits despite their exclusion heated. The suit had undergone cold weather of the abdomen and the wearer could discon-from the initial round of development testing in Minneapolis earlier in January.104 nect it in one quick motion if he needed tocontracts the previous year.101 After some abandon the airplane. Standard A-9 gloves andnegotiations, on July 16 the Army issued Two days later, on January 18, Erickson and A-6 boots were worn over the suit for thermala $5,000 contract, W535-ac-31183, to Lovelace went to 53,800 feet in the Boeing protection. The Type 6B suit was tested atGoodyear for four Type 9 suits. These two- Strato-Lab at temperatures as low as −4 ºF. Eglin Field, FL, in October, and it showedpiece garments used a unique fabric that Boothby and Arthur H. Bulbulian from Mayo promise, the suit still ballooned and limitedpromised significant advantages over previous Clinic monitored the test. The following day, mobility more than desired. By April 1942,fabrics. It was claimed that the fabric would Al C. Reed, Boeing chief test pilot, evaluated Goodrich had progressed to the Type 8Astretch at proper joint locations, yet exhibit no the BABM-3 in a B-17 cockpit. After don- suit. Although much improved, it still didtendency to balloon at operating pressures as ning the suit, Reed spent 30 minutes moving not meet the minimum specifications.106 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby48 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John KearbyAt the same time, the Army ordered 10 slightly Left: During one of the tests,modified U.S. Rubber Type 4A suits at a cost a set of cold-weather leatherof $25,000. The 2-piece Type 4A was made outer clothing was wornfrom dark, rubberized fabric with an integral over the BABM pressurehelmet, boots, and gloves of the same mate- suit. Note the helmet isrial. The Aero Medical Laboratory deemed somewhat different than thethe U.S. Rubber Type 4A suits unsatisfactory, other Akerman suits, withprimarily for a lack of mobility. However, the a flat metal top instead oflessons learned from these suits contributed to being all plexiglass.the development of the XH-2 suit. This two-piece ensemble used detachable rubber gloves Used with permission of theand the lower legs and integral boots were Mayo Historical Unit, Mayodetachable at ring joints just above the knees. Clinic, Rochester, MNUnfortunately, the suit was still too rigid andoffered inadequate ventilation. This was thefinal suit produced by U.S. Rubber.107The Army awarded Bell a contract(W535-ac-24203) on February 7, 1942,stipulating the first suit would be delivered 49within 30 days. Ultimately, developing thehelmet would frustrate Bell, as it would mostother developers. On February 21, 1942, Bellwrote the contracting officer, indicating theyRight and photos on page 48: Researchers at the Mayo Clinictested this unidentified BABM suit sometime during late1942 or early 1943. The suit was typical of the Akermangarments, being tight fitting and well tailored. Note thepleated knee and elbow joints and the leather straps holdingthe gloves and boots on.All used with permission of the Mayo Historical Unit,Mayo Clinic, Rochester, MN Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John KearbyThe XH-2 was the last full-pressure suit produced byU.S. Rubber. Initially, U.S.Rubber had produced suitsdesigned by Army researchers,but the XH-2 was, by allaccounts, an indigenousdesign. Like several of itscontemporaries, the suit haddetachable gloves and legsto allow some tailoring toindividual wearers.National ArchivesCollege Park Collection50 were experiencing problems developing a sat- Above: All of the U.S. Rubber suits were extremely stiff when Above: The XH-2 was a two-piece design with an upper and isfactory method of attaching the helmet to pressurized. The XH-2 used pleated elbows with adjustment lower torso that made donning the suit easy. A zipper ran the suit, and would be unable to make their straps that afforded some mobility that had been lacking completely around the waist and required an assistant to close required delivery date. Wright Field agreed to in early suits. Note the position of the wearer’s head in the it. Note the neck seal under the helmet and the relatively extend the date to April 14, 1942.108 helmet, graphically illustrating suit elongation. Interestingly, small hole the wearer had to maneuver his head through. the pressure gauge on the left glove stood several inches above While at a conference at the National Carbon the garment. Courtesy of the David Clark Company, Inc. Company in Cleveland on February 13, 1942, researchers examined a multi-layer, plastic- Courtesy of the David Clark Company, Inc. to 1.5 psi, and the garment appeared to fabric pressure suit based on the BABM be relatively flexible and offer reasonable garments designed by John Akerman. The covered by a tight fitting, single-piece restraint mobility. Boothby and Akerman believed the suit consisted of an airtight Vinylite bladder layer. A National Carbon employee modeled suit was useable to 50,000 feet. Officials from worn over full-length cotton underwear the complete 15-pound suit while inflated the Aero Medical Laboratory were sufficiently Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbyimpressed to order the suit, now designatedType 7, to be tested at Wright Field. The suitultimately proved disappointing and the Armydiscontinued development, although Akermanlater presented a similar suit to the Navy.109The Army held subsequent conferences atGoodrich and the Royal Canadian Air ForceInstitute of Aviation Medicine in Toronto. AtGoodrich, researchers inspected the texture ofthe material the company was using for theirpressure suits and found it was essentiallysnag-proof and almost self-sealing when pen-etrated by a 0.50-caliber projectile. Stating theobvious, the conference report commentedthat, “it was anticipated that if the suit andits occupant were struck by a 20mm ball, orlarger, the occupant would have no furtherneed for the pressurization.”110 In Toronto,researchers observed tests in the recently 51opened human centrifuge. Once more, recom- B. F. Goodrich developed the XH-1 suit, part of a series of The suit was also fit checked in a Bell P-39D Airacobramendations included the construction of a increasingly better suits that were ultimately judged the best (41-7100). The location is not identified, but given thatgarment that combined the features of a pres- of the Word War II efforts. Bellows at the elbows and knees Akerman was a consultant for Bell, it is likely the Bellsure suit and a G-suit. provided improved mobility. Note the metal rod stretching facility in Buffalo, NY. It is uncertain if an attempt was between the shoulder rings, an attempt to control side-wise made to fly with the suit.After the conference, Goodrich began develop- ballooning. This would become a feature on most of thement of the XH-1 suit. Made of brown rub- subsequent suits designed by Russell Colley. By permission of the Mayo Historical Unit, Mayo Clinic,berized fabric, the suit used bellows supported Rochester, MNby thin steel rods attached to rings at the National Archives College Park Collectionelbows and knees. The chest brace connected On May 22, 1942, Akerman tested thethe shoulder ring joints, and wires ran from a usual, the wearer wore a normal soft flying BABM-5 suit in the Mayo altitude chamber towaist ring to the knees for additional support cover, earphones, and a demand-oxygen mask a maximum of 40,000 feet with no ill effects.and to minimize ballooning. A clear plexiglass inside the helmet. Standard A-6 boots were The following day, Bell chief test pilot Roberthelmet was attached to the neck ring and, as worn over the suit’s built-in feet.111 M. Stanley tested the BABM-7 suit in the Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby chamber. Stanley believed the suit was suffi- Company provided the valves and regula- hypodermic to the other two subjects.”115 This ciently developed to try in an airplane, and by tors. The suit itself weighed about 8 pounds, was meant to show the mobility afforded by June 25, Bell had modified a P-39 cockpit to increasing to 17 pounds when including the the suit under pressure. The Mayo researchers accommodate the pressure suit. Stanley real- helmet, boots, and accessories.113 monitored an Oximeter in Milliken’s ear and ized that the suit and airplane were not well determined his oxygen level was normal dur- matched, primarily because the cockpit was Nay donned the suit, unassisted, in 12 min- ing the entire experiment. too small to comfortably accommodate the utes and doffed it in 5 minutes. During the suit. Two controls at the rear of the side of the altitude chamber tests, Nay could write legibly By the middle of 1942, the Army had consoli- seat could not be reached when the suit was on a chalkboard. The suit, like many of the dated the Goodrich, Goodyear, and U.S. Rub- pressurized, and the landing gear switch was BABM models, had a unique safety feature ber efforts into classified Project MX-117.116 too close to the helmet to be activated with a built into the neck ring: pulling one clamp This was an overarching effort to provide pres- gloved hand. In addition, Akerman and Stan- separated the ring and allowed the helmet to sure suits for high-altitude flight and G-suits ley determined the pressurized air provided by be removed quickly. Normally, the helmet was for high-speed flight. According to a July 1, the airplane contained trace amounts of oil. It removed by releasing a clamp on either side 1942, report, various companies had deliv- is not clear if Stanley ever flew the P-39 while of the neck ring. The suit required between ered eight experimental pressure suits since using the pressure suit.112 3.0 and 3.3 liters of air per minute to keep it October 1940, and testing at Wright Field had inflated to 1.5 psi. John Kearby tested the suit shown that five were unsatisfactory for various Wayne W. Nay, a senior aeronautical engineer at Wright Field and found that it required reasons. The contractors had also delivered52 at the University of Minnesota, tested the BABM-9 suit in the Mayo altitude chamber 80 liters per minute to maintain 1.5 psi; exactly what accounted for the tremendous 10 G-suits, but no formal testing had yet taken place. At the time, Goodyear was under on July 19, 1942. Akerman built this suit for difference could not be ascertained. Subse- contract to deliver four pressure suits, and Bell according to anthropomorphic measure- quent tests at Minneapolis-Honeywell showed Goodrich and U.S. Rubber were to deliver ments provided by the Aero Medical Labora- that even with all six vent valves completely 10 suits each by August 1.117 Eventually, the tory at Wright Field. An airtight, lightweight, open, 1.45 psi could be maintained with Army awarded 13 contracts worth $129,695 close-fitting helmet included built-in ear- only 68.7 liters per minute.114 in support of MX-117.118 phones, microphone, goggles, and a demand- oxygen mask. The suit had an umbilical that A week later, on July 25, 1942, Al C. Reed, Although a good deal of research was tak- combined electrical connections, breathing- William F. Milliken, Jr., and M.J. Lunier ing place on G-suits and pressure suits, it all oxygen, connections, and compressed-air took three BABM pressure suits (a BABM-8, seemed uncoordinated, at least to some of the connections into a single conduit. Special -8a, and -9) to 52,100 feet for 30 minutes researchers involved. The Army attempted to shoulder-to-hip straps provided a hinge line to in the Mayo altitude chamber. According share development information among the automatically facilitate bending and to hold to Akerman’s account, on several occasions contractors and research organizations that the pilot in the sitting position required by the Reed, “went to the medicine cabinet, loaded were working on the suits, but this effort never P-39. The Minneapolis-Honeywell Regulator a hypodermic needle, and pretended to give a proved completely successful. Partly this was Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • just the state of the art at the time; the Inter- The improved Goodyearnet did not exist, and telephone and mail ser- Type 9A suit was tightvice was relatively crude and slow. In addition, fitting, with a large, fulldevelopments in rubber chemistry and fabrics hemisphere helmet thatwere often jealously guarded and protected provided good visibility. Thefrom competitors. Military secrecy further Aero Medical Laboratoryrestricted or delayed access to information. found the suit relatively flexible at its normal 4-psiFor instance, Dr. Harold Lamport from Yale operating pressure, but theUniversity stated that while researchers were zippers leaked excessively.working on pressure suits at the Mayo Clinic,at Welfare Island, NY, and in England, it National Archivesappeared, “there [was] a remarkable paucity College Park Collectionof reports concerning any of these suits.”119 Inretrospect, these criticisms seem exaggerated.The major problem was that developmentwas taking place in many scattered places andhappening very quickly, which did not allowresearchers to engage in their normal cadenceof preparing formal reports, attending confer- 53ences, and exchanging ideas.Partly to address these concerns, in August1942, the Army published the results of aninspection tour that had examined several ofthe pressure suits then under development.At Bell, inspectors reviewed the 18-poundBABM-9 suit developed by John Akerman.At Goodyear, John Kearby and Maj. JosephA. Resch from the Aero Medical Labora-tory donned a Type 9A suit and found the8-pound suit relatively flexible and comfort-able at 4-psi pressure. The inspection teambelieved the suit could be adapted for gunners
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby and men operating in crowded positions in Ward T. Van Orman, now working at Good- At the same time, the Army subjected the the airplane. One of its major problems was year, developed an airtight zipper with over- Goodrich XH-1 to a series of altitude cham- that, like almost all of the suits, it leaked lapping, interlocked rubber strips. Van Orman ber tests that showed the suit still suffered around the zipper. This was solved when filed a patent application on February 9, 1943, from excessive bulkiness, poor mobility when and the patent (2,371,776) was granted on pressurized, and inadequate ventilation. These Goodyear continued to improve the Type 9 suit, resulting March 20, 1945, assigned to the aptly named faults notwithstanding, Kearby took the XH-1 in the XH-3A, which had detachable limbs to allow sizing Wingfoot Corporation.120 to a simulated altitude of 60,200 feet on the suit to each individual. Like all of the rubber suits, the October 2, 1942, and found it offered satisfac- XH-3A exhibited too much contraction when the elbows and Based on the results of Kearby’s evaluation, tory physiological protection. This represented knees were bent, significantly impeding mobility and causing Goodyear built an improved XH-3 suit. This the highest altitude so far.123 a certain amount of pain for the wearer. suit operated at 3 psi and consisted of a tight- fitting single-piece garment that weighed During 2 weeks beginning on October 4, National Museum of the U.S. Air Force Collection 12.25 pounds. A detachable transparent 1942, a crew using four experimental pressure plexiglass dome helmet and integral gloves suits—XH-1, XH-2, XH-3, and XH-6— and boots completed the ensemble. The suit made 5 flights in a B-17E at Eglin Field. Of was donned through a crotch-to-neck airtight these, the XH-1 and XH-3 appeared the most zipper. According to Kearby, it was one of encouraging from a technical perspective, and the lightest suits and the easiest to don and the crew preferred the XH-3 since it was the54 doff. However, much like Russell Colley and Wiley Post—and pretty much everybody lightest and easiest to don and doff. Never- theless, the crew considered all of the suits else—Kearby found the helmet and shoulders too heavy and too restrictive of mobility. The lifted upward under more than 2 psi. In addi- pilots, in particular, complained the suits so tion, the suit was poorly ventilated, causing affected their balance that movements were the wearer to perspire excessively.121 slow and awkward and that they lost the “feel” of their airplane. In fact, the Army ended Goodyear worked on these problems, and the test program early, after only five of nine the improved XH-3A had arms and legs that scheduled flights. The researchers concluded could be detached at ring joints above the that none of the suits was truly satisfactory elbows and knees. These changes facilitated and that all needed further development.124 customizing the size of the suit for each wearer and made donning and doffing a bit Seeking other opinions, on October 20, the easier. Although much improved, the XH-3A Army loaned one of the Goodyear XH-3 still exhibited too much contraction at the suits to researchers at the Naval Air Crew 90-degree bend of the elbows.122 Equipment Laboratory in Philadelphia for Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbyevaluation. Unlike Kearby, who thought the On November 15, 1942, Akerman demon- woven cotton fabric known as “Byrd Cloth”suit easy to doff, the Navy found it impossible strated the BABM-5 suit to LT Donald W. and could be worn over special interwovento remove without the aid of an assistant. Gressly at the Naval Air Experimental Cen- double-layer wool-cotton flying suits forNavy evaluators also found it difficult to stand ter at Philadelphia. Gressly was reportedly greater warmth. Byrd Cloth was named afterfrom a sitting position and impossible to stand impressed with the suit’s mobility and many the fabric worn by ADM Richard E. Byrd andupright under more than 2.5 psi pressure.125 details of the design but felt the 1.5-psi pres- his team during explorations that ranged from sure differential was insufficient. Gressly and the poles to the tropics. The British ArmyAkerman demonstrated the BABM-8 suit, Akerman discussed designing a suit that used adopted the material in the 1940s, and it wastailored for Al Reed of Boeing, at 31,110 feet a 3.5-psi differential (the same as most of the considered the gold standard in military fab-in the Mayo altitude chamber on October 28, other pressure suits then under development), rics for a generation. Known to the British as1942. For this test, Akerman used a 2-pound but apparently, no agreements were reached.127 Grenfell Cloth, the material was a lightweight,air compressor that could supply about tightly woven herringbone twill made of long-55 liters of air per minute. A larger pump, In December 1942, researchers tested an staple Egyptian cotton. The closely wovenweighing about 6 pounds, was available that improved Goodyear XH-3A suit in a B-17F at fabric allowed body heat to dissipate throughcould pressurize two suits simultaneously.126 Eglin Field. This suit was made using a tightly sweat evaporation. Unfortunately, Byrd Cloth also tended to tear at seams.128 Researchers made five flights to altitudes of 10,000 feet, 10,000 feet, 32,240 feet, 39,000 feet, and 40,000 feet and found that the fatigue caused by the suit’s restricted mobility limited long- 55 duration flights. The researchers believed that the suit exhibited too much contrac- tion at the 90-degree bend of the elbow and the hose connectors on the underside of the neck ring were too large and heavy. In addi- tion, the weight of the suit and its supporting John Kearby used a Boeing B-17E, much like this one, to test full-pressure suits at Eglin Field, FL. The airplane could not fly high enough to actually need pressure suits, but it still provided a realistic temperature and motion environment to evaluate the usefulness of the garments. National Archives College Park Collection Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby equipment added approximately 20 pounds would accrue through frequent and regular Although the XH-6B was developed later in the war, per crewmember to the airplane.129 use of high-altitude clothing.132 Goodrich suspended work on the suit after determining the earlier XH-5 provided better mobility. This photo provides In January 1943, Bell finally delivered its first The results of the Army tests led Goodrich a good view of the neck seal inside the helmet. Note the BABM suit to the Army, 8 months after the to develop the improved XH-1C, which was straps on the knees that could be fastened in a variety of revised delivery date. Bell indicated it had soon redesignated XH-5, as well as a largely ways to maintain the desired sitting or kneeling position. successfully tested the suit to 50,000 feet in new suit, the XH-6. In addition to the usual an altitude chamber, and the volunteers that Goodrich chest brace, the XH-6 added a National Archives College Park Collection donned the suit had been comfortable and, flexible wire that ran from the crotch up after some practice, were able to move about and across the chest and around the back. and write legibly.130 Photographs show three of The arms and legs were detachable at rings this model BABM suits in an altitude chamber above the elbows and knees, respectively. The at the same time, so at least that many were separate arms and legs were constructed of fabricated. At the Aero Medical Laboratory, heavy rubber to keep them from ballooning, Lt. Waring L. “Pete” Dawbarn wore the Bell with straps that could be fastened to help the suit for a 1-hour flight in the altitude chamber wearer keep the limbs in the desired position. at 30,000 feet on March 25, 1943. Even Dawbarn evaluated the suit beginning on inflated to only 1.5 psi, the tests revealed April 19, 1943, and found the thick rubber56 the suit suffered a severe lack of mobility that prevented the proper manipulation of arms and legs overly hindered mobility when pressurized. Work on the XH-6 was cancelled simulated aircraft controls.131 and all effort concentrated on the XH-5. Further flight tests at Eglin Field during the The Goodrich XH-5 was probably the best first half of February 1943 attempted to deter- pressure suit developed during World mine the usefulness of the various suits in a War II. The suit was made of laminated B-17 and Republic P-47 Thunderbolt. One rubberized fabric, and ball-bearing joints extended flight in the bomber, to determine facilitated mobility at the elbows and fatigue effects, showed that combat personnel knees. A Goodrich-designed self-sealing could fly at any altitude without additional zipper ran from the crotch to the neck ring. fatigue caused by the pressurized suits, contra- Large, rounded bellows formed the arms dicting earlier tests. Nevertheless, the evalua- and legs to improve mobility, leading to it tors suggested changes to the prototypes, and being called the tomato-worm suit. According researchers wanted to make additional tests to to Russell Colley, “I watched a tomato worm better determine the pathological results that bend about 90 degrees, and the pressure in Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • the worm did not change as far as I could see. The Goodrich XH-5 wasIt did not increase in diameter; so I tried it on commonly called the tomato-the suit.”133 Colley demonstrated the ability worm suit, in referenceto don the 20-pound suit in under 4 minutes to its exaggerated bellowswithout assistance, and he stated it could be on the arms and legs. Thedone in 1 minute with assistance.134 Colley laminated rubber fabricfiled a patent for this suit on August 3, 1943, suit was somewhat bulkylisting Carroll P. Krupp and Donald H. Shook and sagged when it was notas co-inventors and B.F. Goodrich as the pressurized. This was inassignee. The patent (2,410,632) was awarded stark contrast to the tight-on November 5, 1946. fitting Mark IV suit that Russell Colley would laterThe XH-5 was pressurized using an 8-pound, design for the U.S. Navy.24-volt electrical compressor that supplied5 cubic feet (141 liters) per minute (cfm) National Archivesat 3 psi and operated up to altitudes of College Park Collection80,000 feet. The same type of combinedumbilical first used on the Type 6B was fittedat the left side of the abdomen. The wearerwore a standard A-14 demand oxygen mask, 57although Goodrich also developed a smallermask that could be worn instead.The Army ordered a single XH-5 on April 10,1943, at a cost of $3,350, but at least five oth-ers were delivered (one photo shows six suitsin the Wright Field altitude chamber). Reportsindicate more than 30 subjects wore the suitsin the altitude chamber during tests as highas 80,000 feet. In September, Armstrong tookthe suits to Eglin Field and made five flightsaboard a B-17F at altitudes up to 25,000 feet.The evaluators determined that despite itsadvances, the XH-5 was still uncomfortable,
    • Bell delivered this version of the BABM suit to the Army in January 1943, and the suit was extensively tested by Boeing. The tight-fitting suit provided adequate mobility when unpressurized, but proved extremely stiff when pressurized even to 1.5 psi. The suit still required the use of a traditional oxygen mask inside the large clear helmet. The Boeing Company58
    • 59It is uncertain how many BABM suits were produced,but this photo shows three of the suits being worn in frontof the Strato-Lab environmental chamber at BoeingPlant 1 Seattle. Despite being aesthetically appealing, thetight-fitting suits proved disappointing since they werevery stiff while pressurized. John D. Akerman was theprimary designer of the suits, and between late 1941 andthe middle of 1943 he led the development of a seriesof at least nine pressure suits designated “BABM” forBoeing, Akerman, Bell, and Mayo.The Boeing Company
    • suffered from inadequate ventilation, and required too much effort to move the arms and legs when pressurized. Wearers were unable to use the Norden bombsight, the defensive machine guns, or the radio controls on a B-17. Although it might be possible to adapt the airplane to the suit, as built, the suit could not adapt to the airplane. The Army ordered the final Goodyear suit, the $750 XH-3B, on April 7, 1943, and the suit was tested late in the year. For the most part, this suit was an evolutionary development of the garments that had come before. Van Orman filed for a patent on this suit on October 6, 1943, and it (2,401,990) was granted on June 11, 1946. Ultimately, along with the Goodrich XH-5, this suit60 came closest to meeting the stated Army requirements for a full-pressure suit.135As with all of the contempo- During the summer of 1943, the U.S. Navyrary suits, it was impossible tested several of the Army pressure suits at theto stand straight while the Naval Air Crew Equipment Laboratory in Phil-XH-5 was pressurized. This adelphia. LCDR Donald W. Gressly was thewas not considered particu- flight surgeon in charge, assisted by mechani-larly significant but served cal engineer L.W. Meakin. For the most part,to demonstrate the relative the Navy did not identify the suits by a modellack of mobility afforded by number, only by a manufacturer, making itthe suits. Perhaps the most difficult to determine exactly what they tested.significant advantage of the However, their observations were interesting.XH-5 was that it did notelongate excessively, and the Between February 15 and February 19, 1943,pilot’s head stayed centered Meakin and physicist W.E. Scott tested awithin the hemisphericplexiglass helmet.National ArchivesCollege Park Collection
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby 25-pound U.S. Rubber suit under the supervi- connector rings allowed various size limbs to sion of then-Lieutenant Gressly. The suit con- be attached as needed. Accordion pleats in sisted of an upper and lower torso section, and the hip, knees, and elbows were designed to separate arms and legs attached via metal rings facilitate mobility. The pilot donned the suit on the upper arms and thighs. Two zippers through a zipper, covered by rubber flaps, connected the upper and lower torso with an which ran from the crotch to the neck. The inflatable rubber tube between them as a seal. Goodrich garment used a Wiggins Model A15 A metal neck ring formed a twist-type lock diluter demand type oxygen regulator with the joint with the dome helmet. A Wiggins Type diluter side closed off. The suit used a neck seal 108A demand regulator supplied oxygen.136 and a dome helmet connected via a grooved metal ring with a clamp. There was a differen- At 1.5-psi inflation, arm and leg movement tial pressure gauge on the left forearm.138 proved possible but difficult, and it was only possible to stand up from a sitting position During sea-level tests of the Goodrich suit, with great difficulty. The elongation of the Greesly and Meakin found the garment suit made downward vision nearly impossible. leaked around the neck ring and the ring At 2.5 psi, the suit was even more uncomfort- bent easily, making it impossible to secure able and less mobile. At this pressure, the the helmet until it was repaired. The suit, helmet had risen to the point that outward vision was nearly non-existent and it was designed for a 6-foot man, did not fit either of the Navy evaluators particularly well, 61 impossible to stand up even with assistance. making it difficult to judge its comfort. At both 1.5 and 2.5 psi, the left elbow When pressurized to 3.5 psi, the shoulders joint opened unexpectedly. At 3.5 psi, all and helmet rose such that the neck ring movement was impossible. Gressly wore almost covered the eyes. Standing up from the U.S. Rubber suit in the Navy altitude a sitting position was accomplished onlyThis photo shows at least four XH-5 suits in the Wright Field chamber up to 60,000 feet without incident, with great effort, but arm, finger, leg, andaltitude chamber (only a part of the fourth suit may be seen although perspiration proved to be a problem foot motions were “comparatively good.”at center right in a crouched position). Other photos from and movement was largely impossible.137 The suit could be self-donned, but mobility,this series show six suits. The two suits nearest the camera are even when unpressurized, was insufficientnot fully pressurized, allowing the wearers to stand straighter Between June 1 and July 15, 1943, the Navy to enter a fighter cockpit without assistance.than normal (note the hunched position of the suit at the tested the 22.25-pound B.F. Goodrich Type When the suit was pressurized, the pilotback of the chamber). 5E Strato-Suit that operated at 3.5 psi. Metal could not see many of the instruments, could shoulder joints with ball bearings allowed not operate any of the controls on the sideNational Archives College Park Collection 360-degree rotation, and metal arm and leg consoles, and could not reach up to open or Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby of the oxygen inlets, near the ears, resulted The double-layer transparent methyl- in an unacceptable noise level. Greesly and methacrylate helmet was 11 inches in Meakin found the suit unacceptable in diameter with an elliptical top. The front its current form but believed it could be of the helmet sloped down below the improved relatively easily.139 neckline to provide downward visibility, and a perforated tube ran around the front side Concurrently with their tests of the Goodrich of the top to distribute air and prevent suit, between July 5 and July 16, 1943, fogging. The helmet was attached to the suit Gressly and Meakin tested a 20-pound suit using two clamps on a neck ring. Like all of made by the Strato Equipment Company. Akerman’s suits, a third clamp provided a The BABM suit the Navy tested was repre- way to quickly separate the neck ring and sentative of the later John Akerman creations. helmet with one motion in case of an The suit was made of two layers of rubberized emergency. Dry air was trapped between the fabric, operated at 1.5 psi, and consisted of layers of the helmet to prevent fogging.141 five pieces: an upper torso, trousers, a pair of gloves, and a helmet. Metal connecting rings Ventilation air was routed through spring at the neck, waist, and wrists secured the tubing to the middle of the back, head, arms, pieces together. There were leather straps run- hands, and legs. The head ventilation port62 ning from the waist ring over the shoulders to prevent rising and from the waist to the crotch was automatically closed when the helmet was removed. The ventilation valve automatically to prevent elongation. A pocket under each closed when the air supply was disconnected armpit creased by thin wire aided mobility to ensure the suit remained pressurized for a for the arms. Straps across the stomach and short time. This was intended for use when thighs provide breaking points in the inflated the pilot bailed out of an airplane. The The B.F. Goodrich Type 5E Strato-Suit weighed 22.5 pounds fabric for forward bending and sitting. Three Type B-12 constant-flow oxygen mask had and was significant in having detachable arms and legs, clamps attached the gloves to a rubber gasket, two inputs—one from the airplane and one allowing a certain amount of tailoring for the individual. and a standard Army harness and parachute from the bailout bottle—and automatically The neck seal for the helmet is shown at top left. was worn over the suit. There were five zippers switched to whichever one was delivering on each suit: one 11-inch zipper on each side, pressure. Akerman used a Wiggins Type 15A Courtesy of the David Clark Company, Inc. one 11-inch zipper on the trouser at the waist- diluter demand-oxygen regulator.142 line, one 11-inch zipper on the chest of the close the canopy. The suit was not adequately torso, and one 11-inch zipper on the back of Sea-level testing revealed minimal leakage, but ventilated, and perspiration accumulated in the torso. In theory, flaps on the inner side of the suit was difficult to don and doff without the gloves and boots. In addition, the location each zipper provided an airtight seal.140 assistance. Downward visibility was good, Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby The Type 5E was not particularly flexible, and this hunched-over stance was about as straight as a subject could stand. Although evaluators considered limb motion “comparatively good,” a seated pilot could not operate many cockpit controls when the suit was pressurized. Courtesy of the David Clark Company, Inc. 63and elongation and helmet rise were well perspiration was noted. Perhaps the largest Between July 12 and July 21, 1943, Gresslycontrolled. The wearer could easily climb into complaint was a pungent odor, likely from and Makin tested a Goodyear suit that oper-the cockpit of a Vultee SNV-1 trainer (the the particular plastic, within the helmet that ated at 2.5 psi. The black rubberized fabricNavy version of the BT-13A Valiant) without caused extreme nausea. Gressly tested the one-piece suit weighed 12.25 pounds andassistance when the suit was deflated. With suit in the altitude chamber to a simulated used a Wiggins Type 108A demand regulator.the suit inflated to 1.5 psi, gross movements 50,000 feet. He noted that any movement Donning the suit was done through a frontwere easily accomplished, but fine movements, within the suit, or pressing on the outside zipper with rubber flaps that ran from thesuch as adjusting instruments or controls in of the suit, caused a partial deflation, and crotch to the neck ring. A hinge-type clampthe cockpit, were very difficult. The ventila- because of this, internal pressure varied attached to the rubber neck ring tightenedtion in the suit was adequate and no excessive between 0.7 and 1.5 psi constantly.143 the ring around the dome helmet to form Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby64 The BABM-18, created by John Akerman’s Strato Equipment an airtight seal. A pressure gage was on the though the suit lost 1 psi per minute when Company, was one of the most advanced of the World War II left forearm, and built-in restraint straps pre- the air supply was shut off. Since the suit was suits. The suit was fabricated in five pieces: the upper torso, vented elongation of the suit.144 made in a single piece, a tear in a glove or leg trousers that included pressure footings, a pair of gloves, and would render the entire suit useless until it the clear helmet. The oddly shaped helmet was a recurring Tests of the Goodyear suit showed that it was was repaired, unlike the multi-piece suits from theme on several BABM and early David Clark Company impossible to stand up from a sitting posi- Goodrich and others in which a new arm or full-pressure suits. tion without assistance, and even then it was leg could be attached easily. The cockpit eval- impossible to stand upright when the suit was uation showed the wearer had a very restricted Courtesy of the David Clark Company, Inc. inflated. Oddly, Gressly thought the “rub- range of vision and could not see any control ber flap and zipper seal was satisfactory” even or instruments in the airplane. Shoulder, arm, Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • hand, and leg mobility was difficult and The BABM-18 used leathertiring, and there was no ventilation in the straps that ran from the waistarms or legs, leading to excessive perspiration. and crotch over the shouldersThe Navy evaluators also commented that to control elongation,the suit had no provisions for adjusting to although the design of thesubjects of varying heights and weights, helmet still allowed the pilotmeaning that a custom suit would need to to see even if it rose severalbe made for every pilot, something the Navy inches. Note the break pointsbelieved unacceptable.145 at the knees and waist to allow bending.Between November 3 and December 9, 1943,Gressly and Meakin tested a 34-pound General Courtesy of the David ClarkElectric pressure suit. The suit consisted of a Company, Inc.one-piece rubberized fabric inner suit, outertrousers, an outer waist section, a methyl-methacrylate dome helmet, gloves, and metalcrotch reinforcement. The suit used a neck sealand there were small vents in the toes and backof the gloves to help ventilation. The suit fea-tured hinged metal shoulder rings to improve 65mobility and restraining straps across the arms,upper thighs, and from the knees to the instepto prevent elongation. The metal crotch sup-port prevented ballooning and facilitated hipand trunk motion.146The Navy found the suit was difficult to donand doff without the aid of an assistant. Therubber neck seal was fragile and tore easily,and despite the toe and hand vents, subjectsperspired excessively. When the suit was notinflated, subjects “were able to move aboutquite freely,” but when it was inflated to2.5 psi, all motions were made with great
    • Chapter 2: Mark Ridge, Wiley Post, and John KearbyThis Goodyear suit was muchless sophisticated than thecontemporary XH-3A fornot having detachable limbs.Like most suits of the era,the suit elongated excessivelyas it pressurized—note theposition of the subject’s headwithin the suit while inthe seated position. This, ofcourse, made it nearly impos-sible to pilot an airplanewhile wearing the suit.Courtesy of the David ClarkCompany, Inc.66 difficulty.147 The suit was worn by a represen- also seemed to place a different emphasis on are often of lesser or greater magnitude tative of General Electric in the Navy altitude what movements were important. than intended. In the standing or kneel- chamber up to 50,000 feet altitude. At 2.5 psi ing positions, as may be required of in the chamber, fine motions were jerky and Manufacturers’ claims of fine movements bombardiers or gunners, the restriction difficult and the subject perspired excessively. in the fingers and hands do not clearly in motions necessary for these men to represent the basic problem of mobility be efficient are considered too great due The Navy concluded its evaluation of the for it is in the area of greatest diameter, either to the inability to perform the Army suits with a note that, “all suits so far such as the trunk, thighs, and shoulder motions or the fatigue resulting from tested have been characterized by requiring so rotation where mobility has been found such performance.149 much exertion to enable the person within to to be greatly restricted by pressure. Also, maintain a normal sitting position that gen- rotation of the forearm from the elbow The Navy also criticized the suits as too heavy, eralized fatigue is outstanding.”148 The report joint has been exceedingly difficult. All uncomfortable, and not sufficiently ventilated noted that movement was practically impos- movements from these areas of greater to remove perspiration. Seemingly ignoring sible at 3.5 psi in any of the suits. The Navy diameter are of a rough, jerky type and the state of the art in airtight fabrics, the Navy Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John KearbyTop Left: The General Electric suit had a one-piece gascontainer with built-in booties and glove liners. Separateouter gloves were provided. The metal shoulder rings weresupposed to allow increased mobility while pressurized,but testing at the Naval Air Crew Equipment Laboratoryshowed that motion was jerky and difficult, even at arelatively low 2.5 psi.Top Right: General Electric used a two-piece outer suit tofurther control ballooning and provide a protective layerfor the delicate rubber gas container. The outer suit usedintegral boots and had a variety of straps to provide somesize tailoring and control ballooning.U.S. Navy photos, courtesy of the David Clark Company 67 Like most of the full-pressure suits of the era, this General Electric suit ballooned when it was pressurized and significantly restricted mobility. Note the unusual stance of the wearer. GE included a variety of straps on the arms and around the torso in a generally unsuccessful attempt to control ballooning. U.S. Navy photos. Courtesy of the David Clark Company Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearby researchers believed any pressure suit should running risks which not only endangered given company representatives the freedom be made of a lightweight fabric, although they his life, but which were far beyond the call to work with its suits in actual airplanes or noted that the General Electric and Akerman of duty.”151 to take its suits to aircraft manufacturers for suits, which used such fabric, tore too easily evaluation, excepting Bell and Boeing, which under pressure. Acknowledging a problem first Despite the setback, the Army tested the had developed their own suits. Representa- noted by Russell Colley and Wiley Post, the improved Goodrich XH-5 and Goodyear tives at the conference concluded that the Navy researchers found all the suits elongated XH-3B suits at Eglin Field in September Army should discontinue the pressure suit to the point that the helmet rose above eye 1943 and found them airworthy but not development effort but that one suit should be level. The Navy concluded that “none of the ready for combat. The Goodyear suit, in retained to determine fatigue and metabolism pressure suits … have been able to fulfill the particular, severely restricted mobility to the characteristics and for characterizing move- requirements” needed for an operational suit. point that it was unsuited for use at any crew ments physiologically.153 Much like the Army, the Navy concluded the position, but it provided sufficient physiologi- Goodrich suit, although unsatisfactory, offered cal protection to be used on special missions On October 12, 1943, Randy Lovelace, chief the most promise.150 to any altitude readily foreseen as possible. of the Aero Medical Laboratory, advised Nevertheless, the improved suits showed each of the contractors that the Army had The Army program suffered a major setback remarkable advancements over the original decided to terminate MX-117. On October on August 2, 1943, when Maj. John G. Kearby pressure suits tested in 1942.152 29, the Army officially discontinued pressure (1905–1943) was killed after his Lockheed suit development and surplused the research68 A-28 Hudson crashed. He was returning to Wright Field after flight-testing a full-pressure Researchers concluded that none of the suits tested over the past year were sufficiently equipment that had supported the effort.154 suit at Eglin Field. In addition to being advanced to warrant quantity production. At a A USAF Technical Report released in March project manager, Kearby had been the first conference at Wright Field, the Materiel Divi- 1949 stated that, “basically, all attempts to subject to test an Army pressure suit in an sion stated it was time to either buy the suits develop equipment around the principle of altitude chamber and the first to test one as they were or close the project since develop- full pressurization for survival at altitudes had in flight. On October 18, 1943, Maj. Gen. ment had gone as far as possible at that time. failed because of the inability to resolve the Franklin O. Carroll, chief of the Engineering The consensus was that Goodrich was at least fundamental paradox of adequate mobility at Division, recommended Kearby be a year ahead of all the other companies on high pressure.”155 The report further stated posthumously awarded the Legion of Merit; pressure-suit development. After its evaluation that, “it would be extremely unwise and most Maj. Gen. Charles E. Branshaw, commander of several Army pressure suits, the Navy stated unfair to state categorically that the fully of the Air Materiel Command, concurred on that, although generally interested, it had no inflated suit might never be used at high pres- January 10, 1944. The citation noted that, need for high-altitude suits. Many researchers sures for long periods of time (4-6 hours).”156 “Between November 1942 and March 1943, also felt that the entire concept of a pressure Maj. Kearby personally conducted extensive suit competed with the concept of a pressur- The relative failure of the Army full-pressure flight tests of the pressure suit at Eglin Field, ized cabin. Interestingly, the Army had not suit development effort did not deter movies Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 2: Mark Ridge, Wiley Post, and John Kearbyand magazines from featuring the suits. For suit has proved practical in pressure- needs, such as improved oxygen systems, para-instance, the July 2, 1945, issue of Time chamber tests equivalent to 80,000 feet, chutes, and clothing to keep aviators warm.Magazine contained an article entitled, “Sci- or 15 miles above the earth. When fully As legendary test pilot A. Scott Crossfield laterence: A Shape that Came,” along with a photo pressurized, the suit surrounds the airman opined, “During World War II, the armedof a “spacesuit” used in the 1933 movie The with four pounds of air pressure. It pro- services, absorbed with more vital matters,Shape of Things to Come and a photo of a B.F. vides oxygen for breathing, microphone advanced the pressure suit not a whit.”159Goodrich Strato-Suit prototype tested by the and earphones for communication, andArmy in 1943. The article said: electricity for heated underwear. All are ‘piped in’ via a single junction assembly One of the costumes that the cinemadapt- that can be disconnected in one quick ers of H. G. Wells’s The Shape of Things movement. A transparent plastic bubble to Come dreamed up is here. The flyer headpiece is removed in less than a sec- is wearing a “Strato-Suit” developed by ond by a secret device. Donned in two the late Major John G. Kearby of the Air minutes, the suit has airtight and water- Technical Service Command and by B. F. tight zipper enclosures.158 Goodrich Co. Designed for high-altitude flying, the electrically heated, pressurized If only it were so. suit could theoretically keep a man com- fortable at 80,000 feet. The plastic bubble enclosing the head has oxygen for breath- SUMMARY 69 ing, a microphone and earphones for Although several of the pressure suits devel- communication. A man can zip himself oped during the 1930s appeared to work and into the suit in two minutes.157 were even used on a limited number of “oper- ational” flights, none were truly satisfactory.Similarly, the November 1945 issue of Popular All of them were heavy and had extremelyScience contained an article describing the B.F. limited mobility. In addition, there was aGoodrich suit. surprising lack of scientific method applied to their development, most being almost “hobby Made of rubberized fabric, a new flex- shop” efforts rather than true engineering ible, pressurized “Strato-Suit” for flyers projects. The Army efforts of the early 1940s may enable flyers to go farther than ever were better organized and funded but failed before into the stratosphere. Developed to live up to the initial expectations. Despite by the AAF Air Technical Service Com- some limited successes, the waxing winds of mand and B.F. Goodrich Company, the war turned most efforts to more immediate Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • 3
    • Chapter 3: Acceleration Protection3: Acceleration ProtectionDespite the failure of the U.S. military to developed a rubber suit that he could inflate gun and the common mousetrap to his credit,develop a workable full-pressure suit dur- using a bicycle hand pump. However, despite wanted to build an airplane. By 1894, heing World War II, a separate effort yielded a some limited successes during surgery and had largely given up. However, as part of hisperhaps more important garment. Pressure postsurgical recovery, Crile eventually con- research, Maxim built a test rig that used two-suits and “anti-gravity” suits, more often called cluded that the suit was “cumbersome and passenger cars hung using cables from a largeG-suits within the industry, serve two separate, uncomfortable.” As alternate treatments spinning frame; as the machine spun, the carsbut ultimately related, purposes, and their became available, Crile’s suit was forgotten.2 swung outward, simulating flight. Experimentsdevelopment was intertwined. Although not a using the machine continued long after Maximspecific topic of this book, G-suits are discussed Blood pressure, what Crile was attempting to abandoned his attempts to build an actual air-since many of the concepts, institutions, and control with his suit, plays an important role plane. During one of these tests, in Decemberpeople involved with their development are in any human activity and is one of the key 1903, Dr. Albert P. Thurston,3 an engineerinseparable from pressure-suit developments. parameters to maintaining consciousness. It working for Maxim, took a ride and promptlyIn the same year, 1903, that the Wright has long been known that quick or extreme movement can cause a person to temporarily lost consciousness as the car exceeded +6-Gz of centrifugal force.4 Fortunately, Thurston woke 71brothers made their first powered flight at lose consciousness, or to “black out.” This is up a little dazed but none the worse for theKitty Hawk, an American doctor published true of any physical activity, but is perhaps experience. Despite the incident, Maxim saw aBlood-Pressure in Surgery, a book that had most closely associated with pilots flying commercial opportunity and further developedmore to do with aviation than was understood highly maneuverable aircraft capable of high the rig into the “Sir Hiram Maxim’s Captiveat the time. George W. Crile, a cofounder of g-forces. Ultimately, this phenomenon was Flying Machines”5 amusement park ride, whichthe Cleveland Clinic, reported that bandaging linked to blood pressure, and its eventual miti- was installed for the 1904 exhibition at Earlsthe extremities of experimental animals raised gation is credited to a variant of Crile’s suit. Court in London.6 He subsequently built addi-their blood pressure and that compression of tional rides at the Crystal Palace and variousthe abdomen raised it further.1 Crile believed Interestingly, the first blackout resulting from English seaside resorts including Southport,a suit constructed using similar principles centrifugal force occurred only a week after New Brighton, and Blackpool. The Blackpoolmight be useful to maintain the blood pres- the Wright brothers flew at Kitty Hawk. ride, at least, is still operating.7sure of patients on the operating table. To The roots of the event went back to the latecontrol the externally applied pressure more 19th century when Sir Hiram Stevens Maxim Despite this early introduction to the poten-precisely during human experiments, Crile (1840–1916), an inventor with a machine tial problem, the issue of what is now called Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection gravity-induced loss of consciousness pylons. By the time the Coupe d’Aviation THE PHYSIOLOGY OF ACCELERATION (G-LOC) was not widely recognized for over Maritime Jacques Schneider (commonly called a decade. An article published in 1919 by the Schneider Trophy) for the highest speed Acceleration is measured in multiples of the Dr. Henry Head (1861–1940), an English by a seaplane was permanently secured by normal acceleration due to Earth’s gravity, neurologist knighted for his pioneering medi- Great Britain in 1931, loss of visual acuity, or which is 32.2 feet per second per second cal research, observed a phenomenon he called blacking out, had become a serious problem (ft/sec/sec). The normal force (+1-Gz) applied “fainting in the air” in pilots of highly maneu- in closed-circuit air racing. The Supermarine from head to foot upon a standing person verable airplanes such as the Sopwith Camel. S.6B used during the last Schneider Trophy with a mass of 175 pounds is 175 pounds. By 1920, experiments had shown that these race could easily sustain 6-G in turns around However, if this same person is subjected blackouts lasted about 20 seconds and began the course markers, but the physiological to an acceleration of +7-Gz, the force then as the vertical acceleration exceeded approxi- implications were not thoroughly understood applied from head to foot is 1,225 pounds, mately +4.5-Gz. The pursuit airplanes (what at the time.9 creating obvious problems for the body and are now called fighters) of World War I were certainly capable of rendering their pilots unconscious, but popular legend indicates that the pilots who could train themselves to withstand the maneuvers did not want to talk about it because it made them appear72 less professional, and those who could not adequately adapt were dead.8 After the war, air racers frequently talked about fuzzy vision or loss of concentration while making sharp turns around marker Three axes represent the human body when discussing the forces of acceleration. The X-axis (transverse) runs front to back through the chest, the Y-axis (lateral) is side to side through the shoulders, and the Z-axis is vertical from head to feet. A body can be impacted either positively or negatively in each axis. Aerodynamics dictate that almost all accelerations felt by a seated pilot are in the Gz axis. Dennis R. Jenkins Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectioninternal organs. At +7-Gz, blood is as heavy matter how fit and well-trained, is incapable the lungs. Negative transverse accelerationas iron, and the heart is not capable of pump- of functioning in this environment.12 (–Gx) results in breathing difficulties aboveing enough blood against the acceleration to –10-Gx.16 Lateral (Gy) acceleration is not amaintain adequate circulation.10 To increase human tolerance to acceleration, significant concern regarding consciousness, or it is necessary to maintain blood pressure to breathing, but it does have a significant effectAs with any coordinate system, three axes rep- the brain. Unfortunately, the elasticity of the on supporting muscles, such as the neck.17resent the human body. The X-axis (transverse) human vascular system allows blood to pool inruns front to back through the chest, the Y-axis the lower extremities under acceleration.13 Low Applying science to what pilots had been(lateral) is side to side through the shoulders, arterial pressure first impacts the eyes, begin- doing since World War I, researchers—and the Z-axis is vertical from head to feet. A ning around 3-G, when the loss of peripheral principally, at the Mayo Clinic—developedbody can be impacted either positively or neg- vision causes a tunnel vision effect.14 Slowly, a series of anti-G straining maneuvers dur-atively in each axis. The physiological effects cone vision will start to disappear until vision ing the early part of World War II to helpof G-loads vary with the magnitude and dura- is completely lost but the individual is usually pilots maintain consciousness. These involvetion of the acceleration, what axis of the body still conscious.15 If the acceleration continues, specialized, sequenced isometric musclethe acceleration acts against, and where on the unconsciousness follows. Consciousness is contractions and timed breathing routinesbody it is applied.11 regained as acceleration decreases, although that allow pilots to manually press with their this normally results in the dazed or confused muscles and lungs to squeeze the heart, forc-Aerodynamics dictate that almost all accelera- feeling experienced by Albert Thurston. This ing blood to the head. The general proceduretions act upon the seated aviator from head tofoot—in other words, Gz. Positive Gz pushes phenomenon is what Henry Head called “fainting in the air.” is to contract the lower extremity, buttocks, and abdominal muscles while taking a deep 73the body into the seat and drains the blood breath and holding it. At the same time, thefrom the head toward the lower extremities. It Conversely, in a negative Gz condition, much pilot began straining immediately prior to thebecomes difficult to breathe as the ribs and the like when standing on one’s head, blood is onset of acceleration. This was followed by ainternal organs are pulled down, emptying air forced away from the lower extremities and strict cycle of rapid inhaling, straining whilefrom the lungs. The heart has to pump harder toward the head. The first symptom of –Gz gradually exhaling through the partially opento get blood to the brain, partly because the is a sense of facial and, especially, eye fullness glotti. This sequence was repeated at 3-secondblood weighs more; eventually it is unable to and congestion followed by occasional visual intervals. These maneuvers require practicedo so. The magnitude of the acceleration is “red out.” to achieve proficiency, and they are difficulta function of the velocity of the aircraft and to perform and fatiguing at the best of times,the radius of the circle circumscribed. By the Human tolerances to positive transverse accel- let alone in combat. A well-executed anti-Gbeginning of the 1930s, some aircraft, such eration (+Gx) are much higher than +Gz con- straining maneuver provides up to +3-Gz ofas the Supermarine S.6B, were capable of sus- ditions, commonly reaching about +15-Gx. protection and is a very important aspect oftained +6-Gz maneuvers; by the 1970s, this The key problem with transverse acceleration acceleration protection. Many pilots havehad increased to +9-Gz. The human body, no rests in the increased difficulties of inflating mastered the anti-G straining maneuvers, Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection often with life-saving results. Just how well an circles might be useful to reduce heart Militaries recognized the potential impor- individual pilot is able to handle high accelera- activity, suppress fever, and induce sleep. To tance of research into acceleration protection, tions comes down to just how proficient they further this belief, James Watt (1736–1819), and the U.S. Army Air Corps opened the are in the issues of their domain.18 the Scottish inventor and mechanical first human centrifuge in North America on engineer whose improvements to the steam May 6, 1935, inside the abandoned Balloon Although everybody agreed the anti-straining engine were fundamental to the Industrial Hangar at Wright Field. A 20-foot arm allowed maneuvers helped, they were physically tire- Revolution, designed a hand-powered the device to produce up to 20-G, and the sub- some and diverted a pilot’s attention away “rotative couch” for Darwin. Although it is ject could sit or lie on an adjustable platform from flying his aircraft and tracking the unlikely the device was ever built, Darwin at the end of the arm. By 1937, Dr. Harry G. enemy. Researchers continued to look for tools and Watt were probably the first to envision Armstrong (1899–1983) and Dr. J. William that would assist the pilot with G-protection a human centrifuge.20 Heim (1903–1988) used the Balloon Hangar and decrease the need for extended straining. centrifuge to acquire sufficient data to The development of the G-suit was a major By 1877, Austrian physicist and philosopher publish their now-classic paper “The Effects advance during World War II. As with most Ernst Mach (1838–1916), best remembered of Acceleration on the Living Organism.”22 new technologies, its gestation was confus- for his study of shock waves and compression ing and complicated, although the pressures theory, formulated a hypothesis that gravity Armstrong played a major role in aerospace of war kept it short. What follows is not a and centrifugal force were equivalent in their medicine in the United States. After attend- definitive history of G-suits but rather an action on the sensory organs. Albert Einstein ing the University of Minnesota for a year, he74 introduction to many of the individuals and institutions that were also ultimately involved (1879–1955), the 1921 Nobel Laureate in physics, later came to the same general joined the U.S. Marine Corps before return- ing to school. Armstrong received his M.D. in the development of the aviation pressure conclusion—that the effects produced by from the University of Louisville in 1925 and suits discussed later. gravity and inertial forces are indistinguish- entered the Flight Surgeon Training Program able. Charles-Auguste Salathé was probably at the Army School of Aviation Medicine at HUMAN CENTRIFUGES the first physiologist to recognize their Brooks Field, TX. In 1931, Armstrong received equivalence for the cardiovascular system.21 an appointment as flight surgeon to the First Before delving into G-suits, it is appropriate Although largely unrecognized at the time, Pursuit Group at Selfridge Field, MI.23 to examine one of the main tools researchers it was an important realization. used to test human tolerance to acceleration: In a 1934 letter to the Federal Air Surgeon in the centrifuge. Erasmus Darwin (1731–1802), Although human centrifuges were constructed Washington, DC, Armstrong urged giving a physician, physiologist, abolitionist, inventor, by several nations during the late 1800s for higher priority to improving protective flying and poet, and grandfather of Charles, medical reasons, this account will focus on equipment. As a result, the Army assigned explored the nature of sleep in his 1818 book, the acceleration work starting in the 1930s him to the Engineering Division at Wright Zoönomia.19 Darwin believed the centrifugal in Australia and North America as being par- Field. After a while, Armstrong suggested the force resulting from rotating a body in ticularly pertinent to this story. need for a separate medical research laboratory Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionto deal with the physiological aspects of to operate it.27 Armstrong and Heim, would go of 9.5-G at a radius of 9 feet. Unlike otherflying. In May 1935, the Air Corps estab- on to design the Balloon Hangar centrifuge. centrifuges with swinging cabs that were builtlished the Physiological Research Unit with during this period, this one moved the subjectArmstrong as its director. Its initial mission Over the course of the next 6 years, Armstrong and measuring instruments outward andwas to discover ways to provide aircrew pro- developed, among many other things, crash inward along the radius of rotation. Sets oftection from temperature extremes and the helmets and shoulder-type safety belts. A guide rails ran from the center of the turntablelack of oxygen at high altitude.24 In 1939, number of the experiments and investigations to the outer rim. The chair carrying the subjectArmstrong published Principles and Practices Armstrong performed were the first of their traveled on one set of rails and on the other setof Aviation Medicine, considered the standard kind, and he regularly participated as a test were the counterweights necessary to maintaintext for over two decades.25 subject. Critical to the story of pressure suits, dynamic balance. The weights traveled he discovered what is now known as the inward as the chair travelled outward with theIn 1946, the Army named Armstrong Com- Armstrong Line. At approximately 63,000 feet, movement occurring as the turntable reachedmandant of the School of Aviation Medicine at the vapor pressure of water (47 mm Hg) is the the required angular velocity.29Randolph Field, and in June 1949, he became same as the atmospheric pressure (47 mm Hg),USAF Deputy Surgeon General. The following and water boils at the normal temperature ofDecember, he was named USAF Surgeon Gen- the human body. It is important to note thateral. Armstrong retired from the Air Force in this applies to unconfined water, such as saliva1957 as a major general and died in 1983.26 and tears. Normal human diastolic bloodBack in 1935, while organizing the new Physi- pressure is sufficiently high that, contrary to oft-repeated myth, a living person’s blood will 75ological Research Unit, Armstrong sought the not boil in a vacuum, although there are manyadvice of Dr. Cecil K. Drinker and his brother other physiological issues that will quickly killPhilip Drinker, at the Harvard School of Public an unprotected human.28 The Australians wereHealth. Cecil’s research included blood circula- early adopters of humantion and methods of artificial respiration. Philip Meanwhile, on the other side of the planet, in centrifuges. This machinewas an industrial hygienist who, among other mid-1941, the University of Sydney installed was designed by Charles W.things, invented the first widely used iron lung a centrifuge in the laboratory of professor Prescott and installed in thein cooperation with Louis Agassiz Shaw. Sev- Frank S. Cotton (1890–1955) funded by laboratory of Professor Frankeral years earlier, Harvard had built an altitude the Royal Australian Air Force (RAAF) and S. Cotton at the Universitychamber to research pressure related physiology, the Australian National Health and Medical of Sydney. The device wasprimarily as it pertained to deep-sea divers. On Research Council. Charles W. Prescott designed capable of generating 9.5-G.the advice of the Drinker brothers, Armstrong the machine, and White Elevators, Ltd. ofordered a duplicate of their altitude chamber Sydney built it. Two 10-hp electric motors Photos courtesy of Johnand hired their physiologist, J. William Heim, drove the turntable to a maximum acceleration Dodson, University of Sydney Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection The Royal Canadian Air Force (RCAF) com- could realistically mimic the effects of aircraft The United States also built several additional missioned the first modern human centrifuge acceleration on the human body.32 By August human centrifuges. The first came in 1942 in North America (having been predated by 1945, the Canadians had carried out more at the Mayo Clinic under the direction of the original Wright Field Balloon Hangar than 13,000 human runs without a mishap.33 Dr. Edward J. “E.J.” Baldes (1898–1975) and device) under the leadership of Nobel laureate Dr. Charles F. Code. The pair recognized that Sir Frederick Grant Banting (1891–1941), A pit 12 feet deep and 31.5 feet in diameter researchers would need a repeatable method the codiscoverer of insulin and Chair of the housed the device, which, had a single 8.5-foot of replicating flight conditions to uncover the Banting and Best Institute for Medical horizontal arm attached to a central shaft. A physiological underpinnings of the blackout Research at the University of Toronto.30 In 200-hp electric motor rotated the central shaft, problem. The Mayo Clinic machine was not as this case, the centrifuge came in response to causing the spherical gondola to swing out on powerful as the Canadian device, but was more a specific need. One of Banting’s colleagues, moveable joints to an almost horizontal posi- capable than most other human centrifuges of Dr. Wilbur R. “Bill” Franks (1901–1986) tion. The seat was suspended independently the era and designed to specifically allow for was developing a water-filled G-suit and had of the gondola, allowing the subject to be optimal biomedical data recording without used a Fleet 16 Finch biplane trainer to test positioned at different angles inside the gon- the necessity of a huge central motor. It was a the original prototype. It was obvious to dola, including in an upside-down position to collaborative design between the Mayo Clinic Banting and Franks that a safer and more produce negative-G—an unusual feature. The biophysics staff (especially Adrien Porter) controlled means of testing was necessary. Not centrifuge was capable of accelerating to 20-G and the Sperry Gyroscope. The device had a only were flight tests potentially dangerous and in 3 seconds.34 20-foot arm, could generate 2-G in 5 seconds,76 subject to the whims of unpredictable weather, but they also did not provide the precisely An observer outside the centrifuge would and add 2-G per second until it reached 10-G. The centrifuge stored rotational energy in two controlled environment that Franks required turn on lights and sound a buzzer; the 20-ton flywheels purchased from a Cincinnati to understand and improve his creation.31 subject responded by turning the signals brewery, powered by an engine from a “reason- off. A failure to turn off the lights indicated ably priced” wrecked Chrysler automobile. During 1939, Franks and George A. Meek the subject could not see; however, he was The engine drove the flywheels via a normal completed the preliminary design for a likely still conscious and could respond to automotive tire and wheel, although this pre- high-speed human centrifuge. In 1940, the buzzer. A failure to turn off the buzzer sented an initial problem as tires were rationed the National Research Council approved indicated the subject was unconscious. during the war, and Mayo could not explain C$25,000 funding, and Victory Aircraft Researchers monitored the subjects using why it needed one without compromising the built the machine (called an “accelerator”) electrocardiographs, electroencephalographs, security of the project. Fortunately, David M. with assistance from various departments and a photoelectric device attached to the Clark, who will play a major role in this story, at the university. At the time of its open- earlobe that measured blood flow to the head. had contacts within the rationing system and ing in late summer 1941, the RCAF device The latter instrument confirmed that high procured a brand-new tire for the centrifuge. was the fastest and most powerful human accelerative forces greatly reduced the volume Once the flywheels reached about 40 revolu- centrifuge in the world and was the first that of blood going to the head.35 tions per minute (rpm), the operator popped Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectiona clutch to clamp the resting gondola (with The human centrifuge at thethe subject inside) onto the spinning wheels. Mayo Clinic was essential“You’d take off with a tremendous zip,” Baldes in evaluating the originalnoted, “and the g would be applied almost American G-suits, particu-instantaneously.”36 The Mayo centrifuge was larly those developed by theinstrumental in the development of the Ameri- David Clark Company. Thecan G-suit.37 gondola at the end of the arm was a simple tube boxThe second modern American centrifuge with a seat (for sitting exper-opened in 1943 at Wright Field, replacing iments) or table (for prone).the earlier Balloon Hangar device that had The gondola was at the endbeen in use since 1935. This machine, located of a 20-foot arm and couldin the Centrifuge Building (Bldg. 55), had generate 10-G.a 48-foot double boom with a cab on eachend. The device could accelerate to 22-G in Courtesy of the David Clark9 seconds. Capt. George L. Maison, chief of Company, Inc.the Acceleration Unit, was the first to ride thedevice. Between its opening in May 1943 andthe beginning of 1946, 280 persons made sev-eral thousand runs on the machine under the suits. The 23-foot centrifuge, funded by the National Research Council, opened in 1944 Within the U.S. Navy, research in aviation medicine took place at the Medical 77supervision of Lt. Col. F. Gregory Hall, chief and could produce a peak acceleration of Department of Naval Air Station Pensacolaof the Physiology Branch.38 20-G with an onset of 6-G per second. from 1939 until 1946. To support this research, Pensacola opened a 20-foot humanIn late 1943, a group from the University Human centrifuges, it seems, were the centrifuge in 1945 that could operate at 20-Gof Southern California (USC) School of special province of James Henry, who later with a 2-G-per-second-rate of acceleration.Medicine arrived at the Mayo Clinic to replaced Maison as chief of the aptly named On October 1, 1946, the Secretary of thestudy the human centrifuge in preparation Acceleration Unit at the Aero Medical Navy established the Naval School of Aviationfor building a similar device in Los Angeles. Laboratory. To his credit, Henry rode just Medicine at Pensacola that included theIncluded in the group were Dr. Douglas R. about all of the devices in his domain, human centrifuge.40Drury, Dr. William G. Clark, and Dr. James although this may not have been muchP. Henry from the Departments of Physiology consolation to those who followed. Next to By the end of the 1940s, these centrifugesand Aviation Medicine.39 This group, and the John Paul Stapp, Armstrong probably endured allowed researchers to study the effects ofcentrifuge they ultimately built, would play more physical agony in the name of science increased gravitational levels, as representeda major role in the development of pressure than any other man of his generation. by centrifugal force, on the pressure and Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection70 “The Wheel” at the Naval Air Development Center (NADC) in Johnsville, PA, was by far the most sophisticated of the postwar human centrifuges. This device could attain 40-G and was used to train pilots for the X-15 and astronauts for Dyna-Soar, Mercury, and Apollo. The gondola sat at the end of a 50-foot arm and a control room was located above the centrifuge. U.S. Navy Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • The original single-person gondola at Johnsville was hardly the high-tech environment of today. The pilot sat on a simulated ejection seat and initially faced an instrument panel that was little more than an oscillograph with a few extra lights. Many early tests involved the pilot moving the control stick to follow a trace on the screen. During the X-15 program, researchers installed a full X-15 instrument panel, complete with side-stick controllers in the gondola. NASA followed with a simulated Mercury capsule instru- ment panel and controls. Pilots did not think the simulation provided by the human centrifuge was particularly realistic, but it offered at least a hint of the extreme accelerations provided by the X-15 and early manned launch vehicles. U.S. Navydistribution of blood in the lungs, heart, K. “Deke” Slayton, opined, “We feel thatbrain, and legs. Using these devices, the the centrifuge [Johnsville] has been one ofnature of human tolerance to acceleration was our most valuable training devices.”42 Thewell established, the cardiovascular factorslimiting human tolerance to short-term accel- centrifuge was the centerpiece of the Aviation Medical Acceleration Laboratory, located at 71erations were identified, and a general theory the Naval Air Development Center (NADC)of the function and operation of the vascular in Johnsville, PA. The designers of what pilotssystem at 1-G had been firmly established. often called, with a mixture of pride and fear,Many researchers believed they had solved the “the Wheel” anticipated the rapid growth inmajor aeromedical problems in this area.41 aircraft performance and foresaw the need for a new research tool. The resulting centrifugeDespite the increasing sophistication of the had a 10-G-per-second-rate of accelerationwartime centrifuges, one device would ulti- and could attain 40-G, whereas previous cen-mately render all of them obsolete. In 1950, trifuges were limited to 6-G per second and athe U.S. Navy dedicated what was then, by maximum of 22-G. Johnsville had a 50-footfar, the world’s most sophisticated centrifuge, radius as compared with other centrifuges thatalthough it seemed something of a white had radii between 10 and 23 feet. An altitudeelephant at the time. Much later, in 1962, the chamber 10 feet in diameter and 6 feet widechief of the NASA astronaut corps, Donald on the arm provided the ability to test at any
    • Chapter 3: Acceleration Protection altitude, including a vacuum, at temperatures symptoms leading me to think he had a interwar years, the U.S. Navy and U.S. Army from well below zero to nearly 200 ºF. A pair mild cerebral concussion with some gener- Air Corps began looking seriously into the of gimbals allowed the altitude chamber to alized cerebral capillary hemorrhage or at blackout problem. During the early 1920s, assume virtually any attitude. The inner least a marked degree of passive traumatic a pilot practicing for an air race remarked to gimbal provided 360 degrees of rotation at enlargement. Being interested in the case, LT John R. “Jack” Poppen, a nonflying naval rates up to 30 rpm, while the outer gimbal I wrote complete descriptions to Doctor flight surgeon, that his vision began to dim as rotated outward through a 90-degree arc. Schneider of Western University, and to he rounded the pylons at speed but returned to Although the Navy had originally intended Dr. Louis H. Bauer, Medical Director normal on the straight portions of the circuit. the Johnsville centrifuge for research, it of the Air Regulations Division at the The Navy began to investigate the phenomena became a primary training tool for the X-15, Department of Commerce. Both of them in 1921, using an accelerometer mounted on Dyna-Soar, and Mercury programs. In 1963, agreed with my opinion of the cause and a Curtiss JH-4 Jenny to measure aircraft load the Navy replaced the gondola with a larger nature of this condition, namely, it was factors. This was, probably, the beginning of unit to accommodate the three-person-wide due to sudden changes of centrifugal force scientific research into acceleration effects on configuration needed to train for Apollo. while doing high-speed flying in accelera- pilots in the United States.46 Today, the Wheel is a deserted building in an tion tests. There was a duty recovery from industrial park where the NADC used to be.43 this condition in about two weeks and By 1927, Poppen was in charge of the complete recovery in about a month. 44 Aviation Section at the Naval Medical THE BEGINNING OF AN IDEA School in Washington, DC, and was making80 It appears that the National Advisory Based on data from the doctors, Rhode concluded airplanes were reaching the limits great strides toward introducing aviation medicine as a formal discipline. Poppen Committee for Aeronautics (NACA) had of human tolerance to violent maneuvers, was a consultant to the NACA committee the distinction of employing the first person and that since the “pilot is the limiting factor that established a method of investigating hospitalized for “overexposure” to acceleration. … there is no need to curtail performance aircraft accidents and was instrumental in According to a June 8, 1928, letter from flight by over-strengthening the airplane structure changing the way the gyroscopic artificial surgeon Capt. Ira F. Peak, Jr., to Richard V. or by reducing control.”45 In other words, do horizon worked. When Sperry Gyroscope first Rhode, an aeronautical engineer at the Langley not build airplanes capable of greater accelera- introduced the artificial horizon instrument, Memorial Aeronautical Laboratory, an Army tion than an unprotected pilot could endure. the horizon line remained stationary while the Air Corps Reserve test pilot on duty with the Rhode, an otherwise brilliant engineer who symbol of the airplane moved. When many NACA lost consciousness on a flight in Sep- later became assistant director for advanced pilots, including Jimmy Doolittle, experienced tember 1927. Peak wrote: design for NASA, apparently never considered difficulty remembering that the moving bar providing any sort of protection for the pilot. represented the horizon and not the airplane, On examination he showed general- Poppen realized there was a problem. After ized conjunctivitis of both eyes. He also Despite the relatively insignificant budgets a few years of argument, Poppen published showed generalized systemic neurological that hampered the U.S. military during the an article in 1936 that seemed to settle the Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionmatter. Essentially, Poppen’s rationale was that This illustration was used bythe instrument should be an exact analogue Berger Brothers to describeof what the pilot was seeing through the the sequence of events thatwindscreen, a standard still in use.47 often led to a pilot blacking out during a dive-bombingThe Navy soon awarded a small grant to the mission. As aircraft becameHarvard School of Public Health to study faster and more maneuver-acceleration effects. While conducting experi- able, the problem becamements on animals exposed to high g-forces, more widespread and wasPoppen and Dr. Cecil K. Drinker found that not restricted to the verticalabdominal restraint diminished blood pressure maneuvers shown here.effects when acceleration occurred along thevertical axis of the body. During 1932, Pop- Berger Brothers.pen designed a pneumatic abdominal belt that Courtesy of the David Clarka pilot could inflate with a hand bulb prior Company, Inc.to an anticipated exposure to acceleration.48Harry Armstrong and John Heim tested thebelt on the 20-foot centrifuge at Wright Fieldin 1936 and found it of “some benefit.”49 81In 1939, the Navy flight-tested another versionof the Poppen belt, a device later shown in the1941 movie Dive Bomber starring Errol Flynnand Fred MacMurray.50 Pilots reported limited,but not adequate, protection, and there was thelarger problem of needing to anticipate whento inflate the belt, a luxury of time that combatseldom allowed.51 Although the abdominalbelt had been Poppen’s own idea, an indirectlink to George Crile had introduced Poppento the concept of a G-suit. In 1941, Crile wasin an aircraft that flew through the remnantsof a tornado, and the resulting turbulencecaused the flightcrew to lose consciousness; Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection the airplane crashed but Crile survived. In his Crile understood the principle of a G-suit autobiography, Crile wrote: and took his idea to Dr. Eugene F. DuBois, the chairman of the Committee on Aviation After the experience of everyone in the Medicine, one of the branches of the Advisory plane, it seems clear to me that the cause Committees to the Surgeons General of the of the blackout in aviation must be the War and Navy Departments and the Public failure of the blood to return to the brain Health Service.53 Crile had already discussed and the heart because of the rapid ascent his pneumatic suit with DuBois and now sug- of the plane. gested the idea could be used by dive bomber pilots to prevent blackout during the high-G So many times I have seen an uncon- pullout at the bottom of their attacks. DuBois scious patient restored to consciousness agreed the suit might hold promise to protect by being placed in the head-down posi- pilots during violent maneuvers and suggested tion that the blackout seems to me to Crile contact Poppen.54 be just one more phase of the problem that I have been trying to solve for so Separately, in November 1940, Dr. John F. long and which I solved years ago theo- Fulton, an American physiologist at the Yale retically if not practically by the device University Medical School, suggested that82 of the pneumatic suit which provided artificial peripheral resistance, giving pressurized leggings might keep blood from accumulating in the lower limbs during accel- control over the blood pressure within a eration. This was not a new idea, having been range from 25 to 60 mm mercury. This put forward in a German-language book by suit enveloped the body up to the chest. Dr. Siegfried Ruff and Dr. Hubertus Strughold Were an aviator encased in this suit and the previous year.55 Fulton constructed a set of the pneumatic pressure established, the inflatable leggings that worked with the inflat- In 1932, LT John R. “Jack” Poppen, a naval flight surgeon, suit in itself would prevent pooling of the able abdominal belt to force blood upward developed what became known as the Poppen Belt to fight blood in the large vessels in the abdomen from the lower extremities. Fulton did not the effects of acceleration. The concept was valid, but the belt and extremities and would maintain the have access to a human centrifuge for test- needed to be inflated using a hand bulb (shown) in advance conscious state. ing, but Dr. William K. Stewart of the RAF of being needed (a technique not well suited to the flight en- Institute of Aviation Medicine flight-tested vironment). A later version of the device was featured in the I believe that an aviator thus equipped the leggings at the Royal Aircraft Establish- 1941 movie Dive Bomber. would be protected against the failure of ment (RAE) in Farnborough, England.56 the blood to return to the heart and hence Stewart, a respected British pioneer in aviation Courtesy of the David Clark Company, Inc. would have protection against blackout.52 medicine, had been investigating the effects Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionof acceleration and found that about half of Australian physiologist Frank S. Cotton extremities and abdomen would keep bloodthose who experienced blackout had amnesia (1890–1955) was a professor at the University available to the heart. The obvious answer wasand could not remember the event. As the of Sydney specializing in the study of the to make a suit containing a set of bladdershead of a 1940 British research effort, Stewart effects of physical strain on the human body. that automatically inflated to some as-yet-made a flight expressly to experience blackout. In 1940, Cotton showed that the cardiac undetermined pressure. Cotton made the firstAfterward he was disappointed that nothing output, which decreases considerably when suit by cutting up two women’s bathing cos-had happened—until he saw photographs of a change is made from the supine (lying tumes (long before the invention of the bikinihimself unconscious.57 on back) to the standing posture, is nearly rendered salvaging fabric pointless) and gluing fully restored when the standing body is them to a pair of rubber boots. A rubber hoseStewart decided to test Fulton’s leggings. One surrounded by water up to the lower part connected the ensemble to an air compressorof the leggings ruptured during the first flight, of the sternum.60 and pressure valve.and it was evident that the covering fabric wasinadequate. The RAE fabricated a new set of The war in Europe was in full swing, and During November 1941, Cotton began test-leggings that underwent limited, albeit incon- the Battle of Britain took place between July ing the suit and found the concept worked asclusive, testing. In addition, the three-piece and October 1940. This was the first major he had predicted. On the advice of the RAAF,assembly (individual leggings and the abdomi- skirmish fought entirely by air forces, and Cotton took the prototype suit to Britain,nal belt) was awkward to don.58 the RAF Fighter Command gained a well- Canada, and the United States on a demon- deserved reputation during the fight. Ten stration tour beginning November 21, 1941.Although the leggings proved disappointing,they provided an unexpected inspiration for an thousand miles from London, Cotton fol- lowed the battle in the local newspaper. One Unknown to Cotton, by this time the water- filled Franks Flying Suit was already in limited 83American who happened to be at Farnborough article in particular caught his attention: pilots production in Canada. Regardless, Cottonduring the tests. Frederick D. Moller would were suffering from acceleration effects during met with Bill Franks and exchanged ideas. Insubsequently play a significant role in the the dogfights taking place daily over England. the United States, Cotton met with Poppen,development of a workable G-suit.59 Cotton was certain he could find a solution to who was impressed with the gradient-pressure help the pilots avoid the “dreaded blackout.”61 feature of the suit and passed the idea alongAUSTRALIAN COTTON to Moller at Berger Brothers for use in theirAERODYNAMIC ANTI-G SUIT Cotton already knew a considerable amount air-filled suit. about cardiac output. He also knew thatUltimately, American researchers would make German research several years earlier had After he returned to Sydney, Cottonthe most progress toward a workable G-suit, shown that the hearts of great apes were carried out further trials using the Australianbut the Australians and Canadians also recog- nearly empty of blood after centrifuge tests; centrifuge. The test subjects were Flight Lt.nized the potential benefits of the device and it is difficult to pump blood to the head when Robert H. Thompson and Flight Lt. Ken V.conducted extensive research that predated there is no blood in the heart. This led Cotton Robertson; both men were of similar sizemost American efforts. to believe that applying pressure to the lower and build and could use the same suits. In Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration ProtectionThe Royal Austrian The Cotton suit became operational withAir Force conducted opera- No. 452 Squadron at Strauss Airfield neartional trials using Curtiss Darwin, Australia, in July 1943. This, how-Kitty-hawks. Unfortun- ever, amplified a major problem with theately, Australia’s Northern suit. The squadron was responsible for theTerritory capital of defense of northern Australia, meaning thatDarwin experiences hot pilots spent long hours on alert, sitting in theweather most of the year, cockpit or a nearby readyroom, prepared toand pilots complained takeoff on short notice. Unfortunately, thethe suit was unbearably temperatures in Darwin during July are wellhot while sitting alerts in above 80 ºF, with 80-to-100-percent humid-their un-air-conditioned ity. Air-conditioning was largely unheard of atcockpits and readyrooms. the time, and the crews found sitting around in a rubber suit unbearable. Relief cameNational Archives from an unexpected source: Mac RobertsonCollege Park Collection Steam Confectionery Works provided an air- conditioned chocolate van for the pilots to use as a readyroom. This same company had84 March 1942, Thompson began testing the suit 9-G had been obtained. Despite its benefits, sponsored the 1935 air race that had inspired Wiley Post to develop the first pressure suit. using the only Hawker Hurricane (V7476) in pilots reported the suit was hot and uncom- Australia, followed by Robertson in April. On fortable, not ideal traits for Australia during The pilots from No. 452 Squadron were gen- one flight, the Hurricane pulled over 10-G, the summer. erally impressed with the Cotton suit, except- causing minor damage to the airplane without ing the complaints about heat. They did note ill effect to the pilot. Preliminary data was suf- At a conference between the RAF and that frequently the suit did not deflate after ficiently encouraging that the RAAF ordered RAAF on May 15, 1943, the British urged returning to normal 1-G flight, and this the suit into production. Operational trials the Australians to continue in which the made it difficult to fly the airplane smoothly began on October 20, 1942, using Curtiss Australians were developing the gas-filled since the feeling of the controls, particularly P-40E Kitty-hawks at the No. 2 Operational Cotton suit, the British and Canadians had the rudder pedals, was different. There was Training Unit at Mildura, Victoria. Six pilots already fielded the water-filled Franks suit, another, potentially more serious issue with were involved in the tests, including five with and the Americans were working on air-filled the parachute straps between the thighs not extensive combat experience. Flight-tests suits from Berger Brothers and the David spreading correctly when seated. Robertson results generally agreed with the results from Clark Company. expressed the concern eloquently in his report, the Sydney centrifuge, where a maximum of quipping that “I am not yet convinced that Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionone’s matrimonial value will not drop to zero manufactured by Dunlop Rubber Co. Ltd. bladders for the thigh, upper leg, lower leg,if one bails out wearing a suit.”62 He suggested (Australia) and was commonly called the “Zoot and boot. A full-length zipper extended alongfitting guide loops that would hold the thigh Suit” by operational pilots.64 The 25-pound the front of each legging. A short hose con-straps apart when seated, or adopting the suit consisted of a series of overlapping rub- nected the suit to a cylinder of compressedAmerican-style parachute harness that always ber bladders inside a set of rubber latex fabric carbon dioxide, and an acceleration-sensitivestayed separated because of its different design high-waist short trousers and leggings. Initially, valve released gas into the suit in proportionand sewing. the leggings extended from the soles of the to the acceleration it sensed. The suit applied a feet, but later models started at the ankles. gradient of 16 different pressures to the bodyIn August 1943, the RAAF conducted trials The short trousers overlapped the top of the from the ankles to the abdomen.65that pitted a Spitfire Mk V against a Mit- leggings, extending about halfway down thesubishi A6M Zero at Eagle Farm, Brisbane, thigh. This allowed adjustment to compensate By late 1944, the Australians had developedAustralia. The Australians assembled the Zero for different body builds. The shorts contained the so-called “Kelly One-Piece” (K.O.P.) suitfrom parts found on Papua, New Guinea, by a lower bladder that covered the abdomen in an attempt to produce a protective gar-the Allied Technical Air Intelligence Unit. and extended into the legs of the shorts and ment that was lighter and more comfortableThe tests showed the Zero was more maneu- an upper bladder that extended to the lower than the original C.A.A.G. suits. The Mk Iverable than the Spitfire at all altitudes when edge of the ribs. Each legging contained four version of the K.O.P. provided five levels ofneither pilot was wearing a G-suit, but theSpitfire could gain the upper hand if its pilotwas wearing a suit and the Zero’s pilot wasnot. Based on the results of these trials, the 85RAAF decided to equip the Spitfires of No. 1Fighter Wing with the Cotton suit. However,the Australians apparently never used theCotton suit in combat.63The production model of the Cotton Aero-dynamic Anti-G Suit (C.A.A.G.) Mk I wasThe Royal Australian Air Force equipped its SupermarineSpitfire Mk Vs, such as this RAF example, with the CottonG-suit but apparently never used the suit in combat.National Archives College Park Collection Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection gradient pressure from the feet to the waist, using a grant from the Canadian government, could withstand, without apparent damage, while the slightly lighter Mk. II version used Banting purchased the Eglinton Hunt Club over 100 times the normal gravity.”74 only three pressures. Although the suits were near downtown Toronto for use as an aviation an improvement, they still lagged behind the medicine research facility. This was initially It was obviously not practical to suspend pilots Berger Brothers and David Clark suits being known as the No. 1 Clinical Investigation in fluid-filled cockpits, so Franks decided to manufactured in the United States and were Unit and later as the RCAF Institute of develop a fluid-filled suit a pilot could wear. soon forgotten.66 Aviation Medicine.70 In 1940, the institute Although the concept was straightforward, built a low-temperature altitude chamber.71 Franks was uncertain exactly how to construct CANADIAN FRANKS FLYING SUIT the garment. He approached the Dunlop One of Banting’s colleagues, Dr. Wilbur R. Rubber Company, Ltd. and Dominion The Royal Canadian Air Force developed “Bill” Franks, was conducting cancer research, Textiles, Ltd. to develop a suitably strong the first modern human centrifuge in North and it was not immediately apparent what he and nonextensible fabric. The problem then America under the leadership of Nobel could contribute to aviation medicine—until became the joints, which eventually had to use laureate Sir Frederick Grant Banting (1891– he heard James explaining that fighter pilots vulcanized fabric.75 1941), the codiscoverer of insulin and chair were losing consciousness during high-speed of the University of Toronto’s Banting and maneuvers.72 The military considered this one Oddly, the Canadian government declined to Best Institute for Medical Research.67 of the most pressing problems affecting the provide funding for the experiment, but for- performance of their pilots, and James told tunately, Harry McLean, an eccentric Toronto86 Peter Allen, who wrote a paper on the early years of Canadian aviation medicine for the researchers it would provide an enormous tactical advantage if the G-tolerance of Allied businessman known for his philanthropy, donated $5,000 (Canadian dollars), which that Canadian Aviation Historical Society Journal, pilots could be increased.73 allowed Franks to buy the materials and hire a gives much of the credit for getting Sir tailor to make the first suit using an old sew- Frederick involved to Maj. A.A. James of the Earlier in his career, Franks had solved a ing machine in his office.76 This suit covered Royal Canadian Army Medical Corps. James problem with glass test tubes breaking in his the entire body from neck to toes and used had spent a year studying the state of aviation laboratory centrifuge by floating them in a nonextensible outer covering to withstand medicine in other countries. “Realizing that water while they were spinning. Wondering stretching and direct the fluid inward against all countries except Germany were appallingly if the same principle applied to pilots, Franks its wearer.77 A rubber inner bladder held the unprepared to support their aircrews in the experimented with mice in his small centri- incompressible working fluid, water.78 Under coming war, James was determined to see fuge and found they could withstand extreme high accelerations, the fluid was forced inward that situation changed in Canada.”68 accelerations (up to 240-G) when “immersed and downward in the suit, providing sufficient in water up to their necks inside condoms.” pressure on the lower extremities to prevent The Department of National Defence formed Specifically, he observed, “that mice, when the pooling of blood in these areas while sup- the Associate Committee on Aviation Medical suspended in a fluid the specific gravity of porting them against centrifugal force.79 This Research in June 1939.69 Soon thereafter, which approached that of the mouse’s body, allowed the heart to pump sufficient blood to Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionthe head, “thus preventing the occurrence of onset of blackout was experienced by the pilot, of testing was necessary. Fortunately, Franksblackouts and unconsciousness and delaying Flight Lt. Beer, who was not wearing a suit, and George A. Meek had already developedthe onset of fatigue.”80 but not by Franks. The researcher reported, preliminary plans for a human centrifuge, “The suit had been cut to fit me perfectly, and in 1940, the National Research CouncilApparently, unknown to Franks, the idea was standing up … in the airplane I was sitting approved funding. When the device opened innot new. Dr. Heinz von Diringshofen, a medi- down, and when the pressure hit I thought it late summer 1941, it was the fastest and mostcal officer in the part of the German army was going to cut me in two.” Franks found the powerful human centrifuge in the world.88that would become the Luftwaffe, had begun suit confining, uncomfortable, and very hot.85researching prolonged acceleration in flight Development of the suit continued, and induring 1931. Using the centrifuge at the Air Franks had already considered this possibility April 1941, Franks took a prototype of whatMinistry Aeromedical Research Institute in and quickly redesigned the suit to reduce the became the Mk III to Farnborough. It wasBerlin, Dr. Ruff and Dr. Otto Gauer had been coverage. During the redesign, Frank replaced the same place that William K. Stewart hadworking on fluid-filled anti-G suits since late the laces used in the first suit with zippers to tested Fulton’s leggings 6 months earlier. RAF1935.81 Centrifugal force acted on the water make donning and doffing easier. Somewhat pilots evaluated the suit using Fairey Battlesin the suit the same as it did on the blood in after the fact, the first suit was designated and Hawker Hurricanes and found it couldthe body, creating a compensating pressure Franks Flying Suit (F.F.S.) Mk I, while the “prevent blackout up to 9-G.”89 Despite con-gradient. Thus, the suit reduced the pooling second suit became the Mk II. On June 2, sistent complaints of discomfort from pilots,of blood in the lower half of the body and 1940, RAF Wing Commander D’Arcy Greig the evaluation showed the garment performedmaintained cerebral circulation.82 However,Ruff would later conclude that the “idea of began flight-testing the second suit at Malton, Ontario, using an RCAF Supermarine Spitfire as advertised. A report released on August 21, 1941, concluded, “In combat the wearer 87using a double-walled, fluid-filled suit (inner (L1090).86 Although he reported the suit pro- of the suit can follow his opponent howeverwall pliable for adjustment to the body surface vided a needed measure of protection, Greig sharply he turns and still retain his visionand outer wall rigid), although theoretically believed “the principle involving the design of which will enable him to use his [gun] sights.correct, is practically impossible.”83 Not only the suit is sound but in its present form it is In the pullout from a high speed dive at lowhad the Germans already invented the Franks not a practical proposition,” and “many modi- level a protected pilot will be able to forceFlying Suit, they had dismissed it as impracti- fications would be needed” before it could be a following opponent to black out or breakcal. But Franks did not know this—yet. used in combat.87 Franks brought an improved away.”90 However, a second report, written suit back to Farnborough in February 1941, by Stewart, found “difficulties” with the suit.In May 1940, Franks flight-tested the first suit but the trip turned tragic when Banting was Most of them concerned comfort, or the lackusing a Fleet 16 Finch biplane trainer (No. killed in an airplane crash on February 21 on thereof, and the amount of body heat trapped1021) at Camp Borden. Oddly, this was the his way to England. by the suit while waiting on the ground.91first time Franks had ever flown, and he wasinitiated with high-speed aerobatics.84 In two In addition to the suit modifications, it was Despite its problems, the suit held muchtests, one at 6.2-G and the other at 7.7-G, the obvious that a safer and more controlled means promise, and the British and Canadians Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection ordered it into production. Ultimately, furious dogfights like those during the Battle fluid, and this is exactly what the Americans Dunlop produced at least 800 Mk III of Britain, fighter pilots were more likely to did when they developed a G-suit that used suits beginning in September 1941.92 It find themselves escorting bombers over long compressed air to provide counter-pressure.98 subsequently became the first G-suit to distances: a situation that did not endear the The American suit weighed only 3 pounds be used in combat, by the Royal Navy heavy and uncomfortable water-filled suits to compared to 18 pounds for the Franks suit.99 Fleet Air Arm while providing cover for those who had to wear them. In addition, the American suits made by Berger Brothers Eisenhower’s invasion of North Africa at “bounce,” or surprise attack, especially from and David Clark Company quickly replaced Oran, Algeria, in November 1942.93 the rear, had become the preferred fighter- the Franks Flying Suit in RAF and RCAF versus-fighter tactic, and the majority of service. Nevertheless, the forward-thinking Combat trials dragged on for 2 years. Despite pilots never saw their attacker.96 The restricted Wilbur Franks received the Order of the several early successes, such as the battle at mobility of the Franks suit made it almost British Empire (OBE) in January 1944, Oran, and enthusiastic backing from some impossible for a pilot to turn and look aft, and the existence of his suit, previously pilots, British and Canadian fighter pilots making them particularly venerable to attack kept secret, became public knowledge in ultimately judged the Franks Flying Suit from the rear. December 1944.100 impractical.94 In 1946, a National Research Council study noted that “… certain The death knell for the water-filled Franks Late in the war, the Canadians developed objections were eventually raised against the Flying Suit was the testing on the human the air-activated F.F.S. Mk VI, which was a suit, in particular discomfort while ‘at the centrifuge at Mayo that revealed that using air cutaway (or “harness”) G-suit much like that88 ready,’ and difficulty in turning to search for enemy aircraft coming from behind.”95 to pressurize the F.F.S. Mk III provided 2.2-G of protection, significantly more than the developed by the Americans. This suit used a single, continuous air bladder to provide Franks designed the suit specifically to 1.5-G it offered when filled with water. counter-pressure over the abdomen, thighs, protect its wearer from the effects of Researchers at the Mayo Clinic conducted and calves. The suit had zippers on the legs accelerations without regard for the overall this testing in late 1943 and reported it to the and abdomen and lacing adjustments on the operational needs of the pilot. He did this Office of Scientific Research and Development waist, thighs, and calves. The hips and knees based on somewhat faulty logic due to not (OSRD) Committee on Aviation Medicine on were uncovered. The cutaway suit could be being a pilot. Unfortunately, air combat January 19, 1944. Based on this information, worn under or over standard flying clothes. maneuvering was only one aspect of a very the pursuit of hydrostatic suits for acceleration A similar Mk VII suit was a conventional complex environment. Fighter missions protection was largely abandoned in favor of set of trousers instead of a cutaway model. also involved long hours in the cockpit, and pneumatic suit systems.97 Although these suits were called Franks the weight, bulk, and mobility restrictions Flying Suits, three pilots at the Acceleration of the suit made pilots reluctant to wear The major problem with the Franks suit, Section in Toronto largely designed them it. At the same time, the nature of fighter like the German one before it, was the weight and they more closely resembled the combat had changed since the beginning of the 5 quarts of water. The only possible American G-suits.101 of the war. Rather than engaging in short, solution to the problem was to remove the Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration ProtectionTHE AMERICANS in Washington, DC, wrote to Dr. Vannevar Bush was already a legendary engineer and Bush (1890–1974), the chairman of NACA would later become, in effect, the first presi-On December 2, 1940, Maj. Mervin E. Gross, asking for assistance in determining the equip- dential science advisor during the Cold War.102the Executive Officer of the Materiel Division ment necessary for very high-altitude flying. Bush responded that the development of a pressure suit would allow aircrew to reach extreme altitude without imposing the same demand on an airplane (primarily weight) that a pressurized cockpit would. He believed the development of pressure suits for pursuit (fighter) pilots was of immediate importance and offered suggestions for a pressure suit development program along with the full cooperation of the NACA. In addition, Bush pointed out that the Canadians were already developing a water-filled G-suit and suggested the Army follow suit. Bush also suggested that the Air Corps enlist the services of the OSRD Committee on Aviation Medicine.103 89 In the years leading up to World War II, Aus- tralia, Canada, Germany, Italy, and Japan each looked to solve the problems of acceleration with, at best, marginal results. Not surpris- ingly, given the enormous resources available for the war effort, it was the Americans who Although the water-filled Franks Flying Suit Mk III was the first G-suit to see combat, pilots and researchers ultimately rejected the suit as too uncomfortable for operational use. Eventually, the Canadians adopted air-filled bladders with the introduction of the FFS Mk VI cutaway suit. These photos graphically show why this type of suit was known as a cutaway. Courtesy of the David Clark Company, Inc. Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration ProtectionThe Frank Flying Suit Mk Walter M. Boothby (1888–1953). Like manyVII used the same air-filled during the war years, “We were motivated bybladders as the cutaway a high sense of loyalty to our country,” CodeMk VI but featured a recalled nearly 40 years later.104conventional set of trousersinstead of being a cutaway. Aeromedical research at the Mayo Clinic wasSome pilots preferred this already well respected. The 1939 Robert J.design since they did not Collier Trophy, awarded to the “Airlines ofneed to wear flying clothes the United States for their high record ofunderneath. safety in air travel,” gave:Courtesy of the David Clark … special recognition to Drs. Walter M.Company, Inc. Boothby and W. Randolph Lovelace, II of the Mayo Foundation for Medical Educa- tion and Research and Captain Harry G. Armstrong of the U. S. Army Medical Corps at Wright Field, for their contribu- tion to this safety record through their90 work in aviation medicine in general and pilot fatigue in particular.105 The Mayo Aero Medical Unit had two areas of primary emphasis: one dealing with the threats of the high-altitude environment (lack of oxy- gen, decompression sickness) and the second focused on the threats of acceleration-induced blackout and risk related to acceleration in general. Boothby headed the high-altitude laboratory, formed in 1935, in close collabora- ultimately got the science right and produced Unit and offered their services to the Army for tion with Dr. William J. Randolph Lovelace II a truly workable G-suit. a dollar a year. A contract was formalized in and Dr. Arthur H. Bulbulian. Baldes headed February 1942. The original group of research- the acceleration laboratory, formed in 1942, In early 1942, researchers at the Mayo Clinic, ers included Charles F. Code (1910–1997), and his physician partner was Code. in Rochester, MN, formed the Aero Medical Edward J. “E.J.” Baldes (1898–1975), and Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration ProtectionCode was no stranger to challenges in life. fellowship in 1935 and, having an interest in the Mayo Clinic was founded by the MayoHe suffered from scarlet fever when he was 8, aviation, became a flight surgeon in the Army brothers and a group of six other doctors,contracted polio at 12, and was told that he Medical Corps Reserves. His interest in the including Dr. Henry Stanley Plummerwould never walk, a prediction that turned problems of high-altitude flight began during (1874–1936), who is considered by manyout to be wrong, although he wore back and his fellowship at the Mayo Clinic. Lovelace left American physicians to be the “architect ofleg braces. After earning a medical degree Rochester in 1942 to work at the U.S. Army the modern medical practice” and a primaryfrom the University of Manitoba and a Ph.D. Air Forces (USAAF) Aero Medical Laboratory reason for the Mayo Clinic’s early success.111from the University of Minnesota he turned and during World War II conducted high- While the Mayo brothers excelled as surgeons,to research. Code was known for establishing altitude parachute experiments, including one Plummer established the diagnostic, clinical,the role of histamine in allergic reactions jump from 40,200 feet during 1943. In 1958, and, in part, the organizational aspects ofand his basic research led pharmacologists Lovelace was appointed chairman of the NASA the practice. He also designed many of theto develop antihistamines.106 Special Advisory Committee on Life Science, systems now in use around the world, such where he played a key role in the selection of as individual dossier-style medical records. InBaldes was the head of the biophysics depart- the Mercury astronauts. NASA appointed him 1919, this group created the Mayo Propertiesment at Mayo. He earned a Ph.D. in physics Director of Space Medicine in 1964, but he Association, and their private practice becameat Harvard and in physiology at University died in a plane crash on December 12, 1965.109 a not-for-profit entity. The Mayo brothers,College in London.107 who had retained ownership of all clinic Bulbulian’s work as a part of the Mayo Aero properties and furnishings, ceded all of theirBoothby was the first chairman of the AeroMedical Unit, and he interacted formally Medical Unit led to the creation of a series of civilian and then, finally, military masks, assets to this newly formed association. 91with the Committee on Aviation Medicine. notably the A-14 oxygen mask for the Army. Code and Baldes recruited Dr. Earl H. WoodIn 1907, Boothby and Frederick J. Cotton The A-14 mask was frost proof and allowed (1912–2009), to run the newly completed(1869–1938) invented an apparatus to deliver the pilot to talk and eat while wearing it. human centrifuge at Mayo. After Pearlnitrous oxide, ether, and oxygen for use in Bulbulian also was the first director of the Harbor, Wood tried to volunteer for the Armyanesthesia. Subsequently, Boothby, Lovelace, Mayo Medical Museum and designed the Air Forces but remembered, “They refusedand Bulbulian developed the Boothby- exhibits for the Mayo Clinic’s display for me, because I was considered essential toLovelace-Bulbulian (BLB) nasal oxygen mask the A Century of Progress Exposition at the teach medical students.”112 He was teachingand the later oronasal mask that revolution- 1933 Chicago Worlds Fair.110 at Harvard Medical School when Baldesized high-altitude flying.108 and Code recruited him back to his native The Mayo Clinic evolved from the frontier Minnesota with the promise that he could beDr. William J. Randolph “Randy” Lovelace practice of Dr. William Worrall Mayo in charge of the centrifuge.II (1907–1965) studied medicine at Harvard (1819–1911) and his two sons, William JamesMedical School and graduated in 1934. Mayo (1861–1939) and Charles HoraceHe joined the Mayo Clinic for a surgical Mayo (1865–1939). What is now considered Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection Wood quickly realized that tests with animals BERGER BROTHERS Based largely on Moller’s enthusiasm, Berger could not provide sufficiently accurate infor- Brothers—makers of corsets and surgical mation. In fact, “We had to experiment on The Berger Brothers company was based in supports—became interested in “foundation ourselves,” he said, because “we would never New Haven, CT, and had three major subsid- garments” for pilots. Urged on by Moller, do anything on any subject that we didn’t first iaries: Spencer Inc., also in New Haven; Spen- the brothers decided, without consulting the do on ourselves.”113 In the end, Wood rode cer Supports (Canada) Ltd, in Rock Island, Government, to begin developing an inflatable the centrifuge so many times that he most Quebec; and Spencer (Banbury) Ltd. in garment that would provide positive control likely had more blackouts in controlled condi- Banbury, England. The brothers were Darwin of the splanchnic area, a strong support for the tions than any other subject. Code would later Spencer Berger and George Wendell Berger, spinal column, and a safeguard against hernia. comment, “There wasn’t anything we did then and Darwin’s son, Spencer Merriam Berger.116 The company began using principles already that was safe.”114 Beginning in the 1920s, the Spencer compa- employed in the Spencer Abdominal Support nies sold “individually designed supports for Belt, a device the company sold to the medical Wood, realizing how incomplete the scientific abdomen, back, and breasts.”117 The products profession.120 It did not take long for the explanations for the blackout problem were, seemed far removed from aviation. Government to notice. quickly ascertained the true major problem. By comparing blood pressure at heart and While William Stewart was testing John Eventually, Moller and Irving “Doc” Versoy head levels in the centrifuge, he learned that Fulton’s leggings at Farnborough in 1940, produced a simple pneumatic belt and leg- the heart could not generate sufficient pressure the idea caught the interest of an American gings in cooperation with LCDR Leon D.92 to pump blood to the head during periods of high acceleration. At 5-G, blood weighs five who happened to be at the base. Frederick D. Moller was an experienced pilot with more Carson from the U.S. Navy and with the assistance of the National Research Council. times as much, overwhelming the heart’s abil- than 3,000 flight hours, and he immediately The first suit was a set of fitted coveralls with a ity to move it, so blood pressure in the head recognized the potential of the concept but group of air bladders in the calves, thighs, and at 5-G is virtually zero. During his research, believed the entire outfit needed to be abdomen. Zippers, laces, and internal straps Wood found that the force exerted by a tight simplified. He proposed combining an allowed the suit to be adjusted to fit. The turn or a dive recovery could drive the dia- abdominal belt, leggings, and inflatable sleeves 20-pound suit progressively pulsated in seven phragm and the heart down toward the feet as into a single garment that would be easier to zones from the ankles to the abdomen.121 far as 2 inches. That meant the heart had to don than Fulton’s three-piece ensemble. An Initially, the pilot inflated the ensemble by generate even more pressure to pump blood intricate set of tubes sewn into the garment hand just before he expected to need it, but up to the brain. Compressing veins, as done allowed inflation from a single pneumatic like Poppen’s earlier experiments, this quickly by a water-filled suit, was not the answer; source.118 Upon his return to the United States, proved impractical. instead, arteries needed to be compressed to Moller took this idea to Berger Brothers, but it increase arterial pressure.115 is unclear if Moller had a previous relationship The Mayo Clinic evaluated the Berger Brothers with the company.119 suit using a tilt table since the human Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectioncentrifuge was not yet operational. These tests suits for use in the Pacific, but there is no evi- From the positive side of the pump, air passedrevealed that the suit provided approximately dence that they ever saw combat.122 through an oil vapor separator on its way to1-G under the best circumstance, but the mili- the cockpit through a 0.625-inch tube to thetary considered this adequate. Even at 1-G pro- Further development resulted in the 10-pound inlet of the gradient pressure valve assembly.tection, the suit allowed pilots to increase the G-1, which, consisted of tight, high-waist The operation of the valve was completelytolerance from 5-G to 6-G, a small but poten- trousers with built-in suspenders and a girdle automatic. The air came into the distribut-tially important advantage in aerial combat. In containing 17 air bladders in 3 pressure ing head of the control valve and a bellowsmid-1941, the Navy ordered a few hundred zones.123 Like the original suit, the G-1 pro- unit held the valve closed until acceleration vided the highest pressure over the ankles, an exceeded 1.5-G. From the control valve, air intermediate pressure over the calf area and traveled to the 3-G-compensated gradient- abdominal belt, and the lowest pressure over pressure valves actuated by weights and the thighs. Engineers at Spencer designed a syphons as a function of acceleration. The valve that operated off the same engine-driven gradient valve nearest the control valve was air pump that provided vacuum to instru- the high-rate valve that controlled the ankle ments in the cockpit. The Type B-2 or B-3 bladders. Next was the intermediate valve that vacuum pump used by the Vought F4U-1 controlled the calf area and abdominal blad- Corsair and Grumman F6F Hellcat already der. Last was the low-rate valve that transmit- supplied air pressure for a variety of purposes, ted air to the thigh bladders. Once properly including operating de-icer boots and pre- venting air locks in external drop tanks. The adjusted for their specific installation, the valves required no routine servicing.125 93 smaller B-2 pump rapidly lost the ability to pressurize the suit above 20,000 feet, although Because the vacuum pump could not provide the larger B-3 pump remained effective to sufficient pressure quickly enough to fill a about 30,000 feet.124 completely depressurized set of bladders, the suit always contained approximately 0.8 psi. The Berger Brothers G-suit consisted of a set of high-waist The suit began pressurizing at 1.5-G at a trousers and suspenders with a series of inflatable bladders rate of a little over 1.1 psi per G. At 4-G, the sewn inside. The suit had three zippers, one running from the suit provided 3.5 psi on the ankle bladders, top of the waist down to the bottom of each ankle (#1 and #2) increasing to 7.9 psi at 8-G; the other blad- and another running from the top of the waist to the bottom of ders had correspondingly lower pressures. The the crotch (#5). Various sets of laces (#7, #8, and #11) allowed Seamless Rubber Company in New Haven, each suit to be tailored for its wearer. CT, manufactured the bladders, which were generally similar to hot-water bottles made by Courtesy of the David Clark Company, Inc. the company.126 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection In addition to its inflatable bladder, the protection, and the military did not seem ter- abdominal belt supported the back and inter- ribly worried about possible discomfort caused nal abdominal organs, much like a hernia belt. by the suit always being slightly pressurized, The inflation of the rubber bladder within the although the pilots would later decide other- nonstretching fabric belt diminished the area wise.128 In December 1943, the Army ordered within the abdomen where blood could pool. 22 G-1 suits from Berger Brothers, along with If the pilot felt his vision “graying out,” he the equipment required for aircraft, and sent could push hard with the abdominal muscles them to the Eighth and Ninth Air Forces in against the belt; the tension of the belt made England. Based on the initial pilot reactions to the maneuver more effective than shouting or the suits, the Army ordered 1,000 production tensing without a restraint. suits, although ultimately only 500 would be delivered before the suit was replaced by the Berger Brothers provided suits in four sizes: improved G-2. small short, small long, large short, and large long. The suit had three zippers, one running In addition, Navy fighter squadron VF-8 from the top of the waist down to the bottom “Ghost Cats” tested the G-1 during combat of the ankle on each leg, and another running in the Pacific flying Grumman F6F-3 from the top of the waist to the bottom of the Hellcats off the USS Bunker Hill (CV-17) in94 crotch. To don the suit, all three zippers were opened completely and then zipped closed September 1943 and again during the attack at Palau in March 1944. Pilots involved in around the pilot. A set of adjustment laces was the combat attributed several victories over located on the front of each calf and the back Japanese Mitsubishi A6M Zero fighters of each thigh to allow each pilot to tailor the specifically to the advantage provided by Each Berger Brothers G-suit used 17 air bladders in three suit as needed. Generally, once the adjustment the G-suits. In general, the pilots liked the pressure zones to provide counter-pressure on the legs and laces were set for a pilot, they were not used protection provided by the suits but thought abdomen. Since the aircraft vacuum pump could not deliver again, with the pilot donning and doffing the they were too hot and cumbersome. Many sufficient volume quickly enough to fill all of the bladders, suit using only the zippers. The user manual pilots also worried what would happen if the suit always contained about 0.8 psi, making it somewhat said “Bear in mind that, while a snug adjust- they had to bailout over water while wearing uncomfortable when worn for prolonged periods. Although ment makes the suit more efficient, it is not the ensemble—the additional 10 pounds of the suit afforded a decent measure of protection against necessary for it to be uncomfortably tight equipment would not help flotation. The blacking out under acceleration, the pilots universally disliked under any conditions.”127 result was that pilots seldom wore the suits it (and all other contemporary suits). after the initial novelty wore off. Based on Centrifuge tests at Mayo showed that the pilot comments, LCDR Harry Schroeder Courtesy of the David Clark Company, Inc. Berger Brothers suit provided sufficient made several suggestions to the Naval Air Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration ProtectionCrew Equipment Laboratory on how to The G-1 consisted of a set of high-waist trousers thatsimplify the suit and its equipment. The Navy contained the air bladders for the legs and abdomen. Thesubsequently sent this information to the progressive feature of the suit, where different pressures wereAero Medical Laboratory at Wright Field.129 applied to different parts of the body progressively, led to a large and complex set of valves, shown on the table next to theThe reluctance of pilots to accept the G-1 suit model. The three pressure valves (one to the left and two toforced the military to go back to the drawing the right of where the hoses connect) each provided a differentboard. Based on testing with single-pressure pressure. There were several variants of this valve arrange-David Clark Company suits at Mayo Clinic, ment, but they all operated similarly.the Army decided to forego the gradient pres-sure concept and settle on a simple, single- Courtesy of the David Clark Company, Inc.pressure garment. Berger Brothers, DavidClark Company, and Mayo Clinic all cooper- suffered the same altitude limitations as theated in the development of the G-2 suit. Out- earlier B-2 and B-3 pumps, respectively.131wardly, the suit generally resembled the G-1,consisting of a set of high-waist trousers with On the Mayo Clinic centrifuge, the suit pro-suspenders. However, instead of the 17 blad- vided 1.4-G of protection, and researchersders in the G-1 suit, the G-2 contained only at Wright Field generated similar results on5 bladders, and weighed 6.5 pounds insteadof 10 pounds. The bladders consisted of one their centrifuge. Service trials at Eglin Field in February 1944 were satisfactory, and the Army 95rectangular unit over each calf and thigh, plus standardized the G-2 suit on June 19, 1944.an abdominal bladder.130 Within the next year, the military distributed more than 3,500 G-2 suits, made by a varietyThe pressurizing valve for the G-2 was differ- of manufacturers, to combat zones.132ent from the gradient pressure valve used bythe G-1. Under normal 1-G flight conditions, Nevertheless, much like its predecessor, com-the valve did not provide any air to the G-suit, bat pilots did not meet the G-2 with over-keeping it completely depressurized. However, whelming enthusiasm. The reports from theonce acceleration exceeded 1.5-G, the valve with the device. This valve became standard pilots, however, contained at least one veryrapidly increased pressure at the rate of 1 equipment on many midproduction Lockheed interesting observation. Most of the pilotspsi per g, meaning that at 9-G the valve was P-38 Lightnings, Republic P-47 Thunder- refused to use the G-suits as their only cloth-providing 7.5 psi to pressurize the suit. Other bolts, and North American P-51 Mustangs ing and instead wore the G-suit over theirthan connecting the inflation hose to the valve that used B-11 or B-12 vacuum pumps. normal flying uniforms. Despite pilots notprior to flight, there was no pilot interaction Unfortunately, the B-11 and B-12 pumps using the suits as intended, they worked.133 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection THE WORCESTER CONNECTION age 15 to go to work full time. Nevertheless, Clark convinced two older friends to help he continued taking accounting and business finance the endeavor in exchange for equal Engineer and test pilot A. Scott Crossfield classes in the evening, mostly at the urgings ownerships in the company. The business once described David Clark as “one of the of his father. In 1934, he founded a knitting apparently suited Clark and, in quick order, most interesting men I have ever met in the business in Worcester, MA, also with the he received six patents for improved knitting aviation world.”134 David M. Clark was born encouragement of his father. Not having suffi- techniques. Although making a good living in Massachusetts in 1903 and left school at cient capital to start the company on his own, from the knitting business, Clark developed a fascination with aviation and, with a World War on the horizon, sought ways to contrib- ute. Taking his cue from the “dreaded black- out” portrayed in newsreels of the time, Clark decided, sometime during 1940, to develop a garment that could protect aviators from high- G environments, apparently unaware of simi- lar efforts by Cotton, Franks, and Moller.135 One of Clark’s products was a knitted elastic support undergarment for men called the96 “Straightaway,” for which he used an innova- tive technique to change the knitting from ordinary to elastic fabric at the waist, result- ing in an undershirt attached to an elastic The G-2 G-suit, this one made by David Clark Company, was a major improvement over the original G-1. Introduced into combat in mid-1944, the G-2 contained only 5 bladders, compared to 17 on the G-1. More importantly to the pilots, the weight of the suit was reduced from 10 pounds to only 6.5 pounds. This G-suit found use in most front-line fighters and provided about 1.4-G of protection. Despite all of the improvements, one thing the new suit shared with its predecessor was that pilots universally disliked it. Courtesy of the David Clark Company, Inc. Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionabdominal support. This knitting technique Berger Brothers suit, but security restrictions Research Unit (soon to become the Aeroeliminated the cross seams that typically prevented him from discussing it with Clark. Medical Laboratory) at Wright Field. A busi-caused discomfort. It was an innovative gar- Perhaps it was just as well since this forced a ness trip a few days later brought Clark nearment for the time, and the Straightaway was separate development effort—competition is Wright Field, so he made an unannouncedthe subject of one of Clark’s patents. For always a good thing. visit. After a few bureaucratic hurdles, Clarkreasons unknown, Clark decided he could and Benson were introduced. Clark explainedmodify the Straightaway into a garment that Clark, correctly, interpreted this to mean that that he was not seeking contracts but wantedcould help pilots avoid blacking out. he needed a way to automatically inflate the to work with a group that understood the bladder based on changing flight conditions scientific principles, could evaluate his efforts,Lacking money to travel, Clark wrote letters and began a search of a suitable G-valve. Clark and offer advice for improvements. The proto-to the Army Air Corps and Navy Bureau of built a prototype using iron pipe, a domestic type suits would be pro bono since that is howAeronautics, but received no responses. He water valve, and a miniature bicycle pump. the commercial clothing business worked;also paid a traveling stationary salesman friend When swung around vigorously at arm’s companies made prototypes to show to clients$50 to show the Straightaway to the military. length, the device would inflate a football and recouped the development costs via pro-The particular Straightaway that Clark had bladder very quickly; the bladder deflated duction orders. Benson thought this a worth-supplied for this trip had an inflatable football when the swinging stopped. Soon, Clark while idea and arranged to have Clark issuedbladder sewn into the center of the lower part connected the valve to his modified Straight- the appropriate security clearances.137of the abdomen that would apply pressure and away via a pair of 10-foot hoses hooked to ahelp the aviator with the standard gruntingtechniques commonly used to combat loss of compressed air cylinder. Unfortunately, by this time, November 1941, the Navy had In the continuing connection to Mayo, Benson had spent a year at the clinic in 1939 study- 97consciousness during high-G maneuvers. Like transferred Jack Poppen to a new duty station ing aviation physiology. Afterward, Bensonseveral earlier concepts, the bladder needed to and his replacement, LCDR Leon D. Carson, attended Harvard University to continue hisbe inflated using a hand bulb before the pilot expressed no interest in the device since the study of aviation physiology. He became theanticipated he would need the support. Berger Brothers gradient-pressure G-suit was second chief of the Aero Medical Laboratory already in limited production. and, still later, commandant of the new SchoolApparently by shear chance, the salesman of Aerospace Medicine at Brooks Air Forcemanaged to gain an appointment with Jack Finding no encouragement from the military, Base (AFB), TX.138Poppen, who was seemingly impressed with Clark wrote letters to the various aircraftthe garment but not with its operation. Pop- manufacturers describing his garment. Only In the late summer of 1941, Benson suggestedpen wrote Clark a few days later explaining one responded, Boeing Chief Test Pilot Clark contact Dr. Hudson Hoagland, at thethe concept would not work because “it Edmund T. “Eddie” Allen, who confirmed Physiological Laboratory of Clark Universitylacked automaticity that I cannot tell you that some sort of G-protection was necessary in Worcester, MA, who had recently pre-about.”136 By this time, Poppen was well and suggested that Clark contact Maj. Otis sented a paper on acceleration protection.139familiar with the automatic valve used on the O. Benson, Jr., the chief of the Aeromedical Hoagland would leave Clark University in Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection 1944 and, with Gregory Pincus, found the The institution merged with the University of of Columbia. Ferwerda had a prototype Worcester Foundation for Experimental Biol- Massachusetts Medical School in 1997.141 G-suit, which he called a “Pulsatile” pressure ogy, now called the Worcester Foundation for suit, that was ready for testing on the newly Biomedical Research.140 It is best known for Benson and Hoagland both suggested that opened human centrifuge in Canada. The the development of the combined oral contra- Clark contact LT Thomas J. Ferwerda at Naval suit consisted of a heavy open-weave material ceptive pill by Pincus and Min Chueh Chang. Air Station (NAS) Anacostia in the District with seven bladders positioned crosswise in each leg. The pressure pulsated in a wave, traveling from the ankles to the thighs. The suit was tested by the Navy at Cecil Field, FL, in November 1942 but proved disappointing. Ferwerda subsequently modified the suit to include bladders along the arms and abdomen, but this suit also proved disappointing.142 However, perhaps the most important sug- gestion from Benson and Hoagland was to contact E.J. Baldes at the Mayo Clinic, who was also developing a human centrifuge.98 David Clark had already made preliminary contact with Mayo, sending it a Straightaway for evaluation as a postsurgery abdominal support. An exchange of correspondence with The second G-suit designed by LT Thomas Ferwerda included air bladders along the legs, arms, and abdomen that progressively inflated (or pulsated). Ferwerda, like Berger Brothers and David Clark, was convinced that progressively inflating a suit from the ankles to the thighs (and wrists to shoulders) would force blood from the extremities back toward the heart. It was a concept that worked in theory but had little practical effect. Courtesy of the David Clark Company, Inc. Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration ProtectionCharles Code at Mayo led to Clark mention- During 1941, Ernest L. Olrich, the president Company had more than 1,300 employeesing his conversation with Benson regarding of Munsingwear,145 another clothing manu- and occupied nearly 500,000 square feet ofBaldes. Eventually, word reached Baldes, facturer, purchased a majority stake in the factory space, but it ultimately closed its doorswho invited Clark to visit him in Rochester, David Clark Company by buying out the two in 1992.147MN. In a November 1941 meeting, Baldes older partners. David Clark kept 30-percentshowed Clark a scale model of the centrifuge, of the shares, the title of treasurer, and, by Clark’s original water-supply valve had anwhich had a construction budget of $50,000 agreement, absolute control of the company. important failing; if the source pressure var-despite the $1-per-year contract Mayo had Clark’s relationship with Olrich later assisted ied, so did the output pressure. This was notwith the Government. Unusually, Clark had the human centrifuge under construction a huge issue during desktop and laboratorynot brought his suit and valve with him but at Mayo. After the Japanese attack on Pearl demonstrations in which compressed air sup-described the device to Baldes, who approved Harbor, the nation went on strict rationing plied the source pressure, but it would be aof the basic concept.143 of “luxury items” that contained war-critical major concern in an airplane. Along with materials. This included automobile tires. As another engineer at Heald, Waldo Guild,During his discussions with Baldes, Benson, designed, the Mayo centrifuge used an auto- Wilder developed a valve that was immuneand Hoagland, David Clark determined that mobile tire to transfer power from a Chrysler to the variance of source pressure. The valveideally a G-suit should “milk” the blood from drivetrain to the flywheels that drove the could easily supply an inflation pressure ofthe lower legs up toward the torso since a centrifuge; because of the rationing, it was 1 psi per G. It was a workable, if large andsimple belly bladder might not be sufficient impossible to acquire tires without violat- heavy, solution to pressurizing a G-suit.148to delay loss of consciousness. Unknown toClark, this was not a new concept; the pro- ing the security restrictions surrounding the project. Clark knew the Government had To create a more sophisticated anti-G gar- 99gressive or gradient suits developed by Frank appointed Olrich the chief of rationing for ment, Clark needed somebody that couldCotton in Australia and Fred Moller at Berger Minnesota, and he quickly arranged the deliv- sew better than he could. Julia Greene wasBrothers shared a similar trait. ery of two new tires to Mayo.146 the daughter of Irish immigrants and a few years older than Clark. Greene already workedBack in Worcester, Clark developed a “bandage” Another of Clark’s contacts proved handy for Clark and was easily convinced to helphe could wrap around his legs. Hooked to when it came time to design a more sophis- develop the garment. The new G-suits starteda 50-psi air source, this bandage inflated ticated valve to operate the G-suit. Henry conventionally enough; Clark purchased sixprogressively from the ankle upward, forcing Wilder, an engineer at the Heald Machine khaki twill coveralls, two each of three sizes,blood from the legs into the torso. Clark Company, also located in Worcester, had in a store downtown. Greene altered the cov-demonstrated the garment for Baldes and been a Boy Scout with David Clark. After its eralls to provide a tight fit in the buttocks andCode in Worcester as they passed through on founding in 1826, Heald specialized in preci- sewed inflatable bladders into the lower legs,their way to convince Earl Wood at Harvard sion grinding machines, especially ones that thighs, and belly. These became the first Pro-to join the human centrifuge program at the shaped the inside surfaces of hollow, cylin- gressive Arterial Occlusion Suits (PAOS).149Mayo Clinic.144 drical parts. At its peak, the Heald Machine Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection The abdominal bladder was there not to the suit. This was significantly better than the on the principle of a tourniquet, placing compress abdominal arteries but to reduce 1-G provided by the Berger Brothers suit.151 strong encircling pressure on each thigh to the downward movement of the diaphragm stop the blood circulation to the limbs when and heart by supporting the abdominal David Clark returned to Worcester and began the pilot experienced acceleration.153 wall. Experimentation with different sizes designing a new G-suit. Despite the relative of orifices between the various bladders led success of the Mayo tests, each of the sub- The first AOS provided about 2-G of protec- to a configuration where, at 2-G, the suit jects had emerged from the centrifuge with tion and eliminated much of the petechiae would inflate progressively to 20 psi at the petechiae (small bruises) on their skin seen with the original PAOS. Although this ankles, 10 psi at the knees, 5 psi at the hips, where the bladders inflated. Wood thought was less protection than the PAOS provided, and 1.25 psi at the top of the belly.150 these might be an indication of too much it was still twice that provided by the standard pressure, or perhaps the friction of the latex Berger Brothers suit. However, the research- The Mayo Clinic had not yet completed bladders which had to stretch considerably ers ultimately determined the suit was not the human centrifuge, so Baldes and Wood as they inflated, caused the bruises. Clark acceptable because of the length of time it cut tested Clark’s suit using the same tilt table revised the size and shape of the bladders, off circulation to the limbs during prolonged researchers had previously used to test the and switched to a dipped, rubber-coated maneuvers and the resulting discomfort. Still, first Berger Brothers suit. The two doctors material to eliminate most of the stretching. it demonstrated the concept was workable.154 believed the suits might be able to provide a The “milking” idea of progressively inflating level of G-protection greater than that pro- the suit from the ankles upward did not seem After these tests, David Clark realized he100 vided by the Berger Brothers suit and asked Clark to leave them for further testing. to elicit any positive (or, for that matter, negative) comments from the researchers. needed some method of keeping track of the suit designs, so he retroactively called the orig- Although Clark still believed the idea was inal PAOS suits Model 1 and the first AOS In November 1942, David Clark witnessed potentially valuable, it also added considerable suit the Model 2.155 Each of the two-dozen the researchers at Mayo testing his G-suits complexity, and he eliminated it from the Clark experimental G-suits that followed was on the newly completed centrifuge. Earl next prototype suits. These changes resulted different, sometimes vastly so. In one model, Wood was the first to try the coveralls in the in the Arterial Occlusion Suit (AOS).152 there were arm cuffs that provided measur- centrifuge and found that they provided mea- ably better protection but at a huge increase surable protection. Dr. Edward H. Lambert The AOS was a pair of high-waist trousers in complexity, and they also severely restricted (1915–2003) then tried them, with the same with five interconnected air bladders: two the mobility of the pilot’s arms. Often, the results. David Clark also got a couple of runs fitted around the calves, two around the suits were similar except for the size of the at 5-G, providing valuable experience for the thighs, and one on the abdomen. They began abdominal bladders: the otherwise identical man that was designing the garment. Tests to inflate at 1.5-G to compress the arteries Model 5 used a 1.5-liter bladder, the Model 6 showed the PAOS could increase tolerance up in the lower half of the body, increasing the used 1.0-liter bladder, and the Model 8 used a to 3-G, meaning that a pilot that normally blood pressure in the upper half almost instan- whopping 4.0-liter bladder.156 blacked out at 5-G could tolerate 8-G with taneously. In essence, the suit worked Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration ProtectionThese early rounds of centrifuge studies protection was the application of pressure on not particularly critical. The simplest type ofprovided some surprising results that guided the abdomen and trunk. Pressurizing the legs leg bladders should be used, “since it is neces-the development of future G-suits. Research- was necessary for the effective use of abdomi- sary only that they be of such size as to ensureers discovered that the chief factor in suit nal pressure, but the amount of pressure was reasonable pressure transmission to the legs in spite of relatively wide variations in fit.”157 A conference was held at Wright Field to dis- cuss whether a G-suit, better than the Berger Brothers garment used by the Navy, existed that the Army could field in relatively short order. David Clark, Charles Code, and Earl Wood attended, and the Mayo researchers believed the AOS could fill the need. Clark was not so certain, feeling the suit was overly complicated and probably not sufficiently comfortable for long-term use in a combat zone. In addition, the Heald valves were large, heavy, and designed to operate off a fixed Left: The David Clark Company Model 8 Arterial Occlusion 101 Suit (AOS) used bladders on the abdomen and around the thighs. Like all of the AOS suits, the thigh bladders functioned almost as tourniquets, increasing the blood pressure in the upper half of the body almost instantly. Researchers, however, worried about the effect of cutting off circulation to the lower legs and pilots objected to the discomfort during maneuvering. Right: This variant of the AOS used a pair of arm cuffs, in addition to the abdominal and thigh bladders, in an attempt to keep as much blood volume as possible near the heart. Pilots found these made it nearly impossible to hold the control stick during maneuvering, and the concept was quickly dropped. Courtesy of the David Clark Company, Inc. Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection The Cornelius control valve for the World War II G-suits was ingeniously simple. A counterweight reacted to G-load and operated a valve that either allowed com- pressed air to enter the suit or for the suit to exhaust the air as needed. Considering that it contained no elec- tronics or complicated feed- back loops, the valve was remarkably accurate. Courtesy of the David Clark Company, Inc.102 50-psi source, not whatever source existed inflated (about 0.8 psi) at all times in order was working with Mayo and Wright Field on an airplane.158 The conference reached no to react quickly enough to G-loads. This on pressure-sensitive switches for parachutes. particular conclusion. increased the discomfort level of the suit on In addition to designing various air compres- long missions since it somewhat restricted sors for aviation applications during World Finding a pressure source on airplane—before movement in the cockpit.159 War II, Cornelius founded a company that the advent of jet engines and their omnipres- has become one of the world’s leading ent bleed air—was a challenge. The Berger During the Wright Field conference, it suppliers of beverage dispensing equipment, Brothers suits used the aircraft instrumenta- became obvious that the Heald valves that including a foam-free draught system for tion vacuum pump. Unfortunately, this small David Clark was using would not work in beer. Cornelius soon developed a suitable pump only provided 14.7 psi at sea level, an operational environment. Baldes turned valve under the guidance of David Clark and meaning the suit had to be kept partially to Richard Cornelius in Minneapolis, who the researchers at Mayo Clinic.160 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration ProtectionIn 1943, Baldes arranged for the Army to One of the features of thebail a Douglas A-24, essentially an olive-drab David Clark Companyversion of the Navy SDB-3A Dauntless dive G-suits that made them lessbomber, to the Mayo Clinic for in-flight expensive to fabricate andevaluation of G-suits. Showing a good sense easier to maintain was theirof humor, the researchers named the airplane bladder system. By moldingthe G-Whiz.161 Lambert instrumented the many of the interconnectedairplane, and the chief of the Army Reserve bladders as a single piece,contingent in Rochester, Lt. Kenneth Bailey, leakage was minimized, asassisted Mayo with maintenance and fly- was a lot of hand assembly.ing duties. Bailey soon learned to fly precise, These are some of the moldsrepeatable profiles that allowed researchers to used to make the bladdersacquire the necessary data.162 during 1945. suit. The inflation hose passed through the Researchers tested the new suit in the MayoMost of the prominent researchers in the belly bladder and branched through the thigh A-24, and James Henry came from USC to Courtesy of the David Clarkfield of G-protection and Government sections and into the calf sections to ensure evaluate the suit in the airplane. Lambert had Company, Inc.leaders from the USAAF, U.S. Navy, RCAF, the folds of the two layers of fabric could not installed movie cameras in the airplane so thatand RAF, convened at Wright Field in early occlude the flow. Clark carefully shaped the researchers could review the subjects’ reactions1944 to plot the course for pilot protectiveclothing for the rest of the war. One of the belly bladder to ensure it would not provide uncomfortable contact with the pelvic or rib to the suits after landing. By now, Bailey had pretty much perfected the art of taking the 103decisions that came out of this conference bones when inflated. lumbering dive bomber up to 10,000 feet, put-was that the Allies would adopt the simpli- ting it in a spiral dive, and producing whateverfied Berger Brothers G-suit. Although most When Earl Wood arrived the following G-load was required for about 15 seconds.present apparently agreed that the Clark AOS morning to say his goodbyes, Clark showedprovided greater protection, they deemed the him the experimental suit. Wood found it Coincidences are often critical. As Mayo wasBerger Brothers suit adequate, and the pilots quite comfortable, even at full inflation. He testing the suit, E.J. Baldes phoned Davidpreferred it. After the meeting, Earl Wood cancelled his outbound train, told Clark Clark with news that he had met Harrywent to Worcester to tell David Clark. to make a “more finished” suit, and called Schroeder, the man that had evaluated the Charles Code. Within a few days, Julia effectiveness of the 300 Berger Brothers G-1David Clark was not ready to give up. Over- Greene and fellow seamstress Rose Arlauskas suits the Navy had sent to combat squadronsnight, he fabricated a prototype that took the made three of the new suits in various sizes. in the Pacific. Baldes steered Schroeder tobest of the Berger Brothers suit and the AOS. Wood took the new suits to the Mayo Clinic Worcester, where he met Clark in July 1944.It had a one-piece bladder system that com- and found that the suit provided adequate Schroeder stressed that the Berger Brothersbined all five bladders, in the Berger Brothers protection when inflated at 1 psi per G. suits had worked well, when the pilots Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection conceded to wear them—all were reluctant. at the Electric Blanket Division of General Unfortunately, tests at USC also showed the The suits were hot in the tropical climates, Electric (GE) had contacted Harry Schroeder GE suit provided no measureable protection. uncomfortable, too heavy, and did not with an idea for a G-suit, developed in By the end of the war, the Pioneer Products contribute to survival if the pilot abandoned consultation with Dr. Harold Lamport at Yale Division of GE had evolved the concept into his airplane for some reason.163 University. General Electric used capstans the L-12 suit, which, provided slightly better on the calves and thighs instead of bladders, protection than the Clark G-3 on the Wright David Clark listened intently, and when making it more comfortable for the pilots Field centrifuge. Unfortunately, the L-12 Schroeder left for Wright Field a few days (the stomach bladder remained). The capstans needed higher pressure than was available later, he had an improved suit that weighed were large inflatable tubes that ran vertically on combat aircraft of the era, so it was never only 3.5 pounds. The new coveralls did not along the legs on the outside of the suit. Each ordered into production. The capstans, on the use lace adjustments but had several zippers capstan attached to a series of interdigitizing other hand, would reappear on the first Henry that allowed it to fit each pilot. Testing in laces that encircled the limb; as the capstan partial-pressure suit.168 the Wright Field centrifuge revealed the suit inflated, it tightened the laces around the provided adequate protection, but Schroeder limb and provided the required skin pressure. In the meantime, David Clark’s experimental had several ideas to improve the suit, mostly For this to work, the suit had to fit almost seamstress, Julia Greene, left Worcester to to make it more appealing to the pilots. He perfectly. A loose fit would easily allow the follow her husband to Burbank, CA, where had Clark add a large pocket on the front capstans to exceed their useful limit without he had recently gotten a job with Lockheed. of each shin, a smaller pocket for a hunting tightening the laces sufficiently to exert any This move would prove fortuitous a little later104 knife on the inside of the right shin, large chest pockets that were out of the way of the pressure on the skin. A tight fit provided too much counter-pressure, potentially shutting in the story, when Greene went to work for Henry while he developed his partial-pressure parachute harness, and a pocket for a pack of off circulation to the limb.166 suit. Back in Worcester, Alma Charland took cigarettes on the upper left arm. David Clark over the seamstress duties and, being more developed eight standard sizes (four waist Unfortunately, testing at both Wright Field experienced at making patterns, redesigned sizes in 2-inch gradients, with “shorts” and and Mayo Clinic showed the initial suit the Z-1 suit to better integrate the shin pock- “longs” in each size).164 These changes satisfied provided no measureable protection. The ets. The Navy ordered the modified suit into Schroeder, and he took the modified G-suit to major problem was that the capstans and quantity production as the Z-2.169 Washington. Schroeder named the new suit interdigitizing laces could not react quickly Z-1, the Army designated it G-2, and both enough given the available pressure. After the Despite the laboratory success of the Z-2 suit, suits were ordered into production from a tests, sometime in early 1944, Helen Lester pilots still did not like it; many preferred variety of manufacturers.165 visited David Clark to discuss the capstan blacking out to wearing it. “Pilots are just system.167 David Clark told Lester about that way,” Wood said. “They don’t think Sometimes a completely different idea comes the USC centrifuge, and the GE team took they need anything.”170 But the pilots had a from an unexpected source. Back in early their suit to California where James Henry point. On the ground, the suit was hot and 1943, Helen Lester and David C. Spooner was working on a partial-pressure suit. uncomfortable, and crew rooms without Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionair conditioning felt like saunas in tropical attack. If the abdominal bladder inflated too During testing in the Mayo centrifuge, 12 sub-climates. In combat, the suit could actually quickly, it gave not the usual hugging feeling jects made 320 runs and researchers used visualbe painful. During high-G maneuvers of but something like a punch in the stomach. symptoms as a subjective measurement and thelong duration, the pneumatic bladders could Although a clinical success, G-suits were blood content of the ear and ear pulse as objec-stay inflated for up to a minute and feel like proving to be an operational failure. tive measurements. The centrifuge runs lastedtourniquets. The suit could cut off blood 15 seconds with a maximum acceleration ofcirculation to the legs, which would ache CUTAWAY SUITS 6-G attained at a rate of 2-G per second. Thewith the pain of ischemia like that of a heart Army conducted similar tests at Wright Field Up to this point, all G-suits, whether and the Navy in Philadelphia. All of the tests designed by Berger Brothers or David Clark, confirmed the new Berger Brothers and David had been high-waist trousers or coveralls. Clark cutaway suits provided adequate protec- However, the reluctance of fighter pilots to tion, although somewhat less than the earlier use the suits, mostly due to discomfort, was coverall type.172 The Army evaluated both worrisome to the researchers. In response, company’s suits at Eglin Field in June 1944 George Maison at Wright Field suggested and determined that the Clark suit was supe- developing a “cutaway” version of the suit rior to that from Berger Brothers. The AAF that a pilot could wear over whatever clothing Proving Ground Command recommended was appropriate (i.e., heavy uniforms in cold that the Berger Brothers suit be discontinued climates and lighter uniforms in the tropics). It was largely the same path taken by Wilbur and all future suits be procured from David Clark Company.173 105 Franks in Canada. This resulted in the G-3 suit, a cutaway version of the G-2 that looked Beginning February 8, 1944, the Army Air like a set of trousers in which the front of Technical Services Command (ATSC) spon- the knees, crotch, and buttock area had been sored a set of conferences to standardize cutaway. There was just enough material to G-suits and their supporting equipment as keep the five bladders in the abdomen, thighs, part of classified Project MX-389.174 Darwin and calves in their proper positions. The suit Berger, Spencer Berger, David Clark, FredThis is the David Clark Company version of the Z-2 G-suit. came in four standard sizes and used lace Moller, and Capt. George A. HallenbeckNote the zippered pockets on the shins, chest, and sleeve. adjustments for fitting. The David Clark suit from the ATSC attended all of the confer-Sometimes it seemed as if the location and shape of the pock- weighed 2.25 pounds and the Berger Brothers ences, with other attendees as required.175ets were as important as the acceleration protection provided suit was about a half pound heavier due toby the bladders hidden inside the suit. its rubber bladders. The G-3 used the same Perhaps the most significant agreement to airplane-mounted equipment as the G-2 and come out of the conferences was to standard-Courtesy of the David Clark Company, Inc. was operationally interchangeable.171 ize the design for the G-3 cutaway suit. On Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection February 10–11, Moller and Doc Versoy from None of the safety issues won over pilots but Berger Brothers and David Clark and John performance data finally did. A P-51 Mustang Chisholm from the David Clark Company fighter group of the Eighth Air Force reported drew up patterns for the standardized G-3 that pilots wearing anti-G suits shot down suit using an interchangeable bladder system. 67 enemy aircraft per 1,000 operational hours, One of the major issues was that the Berger compared with only 33 kills for other pilots. Brothers preferred bladders made of rub- A doubling of the kill rate was persuasive.177 ber or synthetic rubber, while David Clark used Vinylite-coated nylon fabric. In the Based on comments from the combat zones, end, everybody agreed that Berger Brothers a slightly improved Type G-3A suit was soon would continue to use rubber bladders and developed to further improve comfort. The David Clark would use coated nylon fabric outer suit used a sage-green, basket-weave but that each company would use the same nylon cloth, and the inside areas around the design, making the bladders interchangeable. bladders used an oxford-weave cloth because it Somewhat later, the Army directed both com- tended to slip less around seams. The new suit panies to switch to neoprene bladders that provided 1.1-G of protection on the Wright were even more durable and somewhat lighter. Field centrifuge and 1.2-G on the Mayo Clinic machine. The suit came in four sizes: small106 Things moved much quicker in 1944, and Berger Brothers put the new suit into produc- short, small long, large short, and large long, and laces over the calves, thighs, and flanks tion on February 25, and David Clark fol- provided custom fitting. Surprisingly, the lowed on April 15. Munsingwear and several G-3A weighed almost a pound more than the A major advance in G-suits came with the advent of a other manufacturers also produced the suits. initial Clark G-3. Late in its production, the “cutaway” suit. This allowed pilots to wear the G-suit over By the end of 1944, more than 4,100 G-3 G-3A came with a device that allowed the suit whatever clothing was appropriate for the conditions they suits were delivered to the Eighth, Ninth, and to be inflated by mouth and used as a life vest were operating in, such as heavy uniforms in cold climates Twelfth Air Forces, and in November 1944 if the pilot was forced into the water.178 or lightweight cotton in the tropics. The cutaway contained the Army officially accepted the G-suit as just enough material to support the five bladders in the abdo- standard equipment and began issuing one to After Germany fell, the United States cutback men, thighs, and calves. This also reduced the weight of the every fighter pilot.176 many defense contracts, but the need for suit to just 2.25 pounds. The pilots still did not like the suit, G-suits kept both Berger Brothers and David but they began wearing it since data showed it significantly The G-3 suit became operational during Clark busy. When V–J Day arrived, the mili- increased their kill rate. the fall of 1944, and data soon showed that tary cancelled many contracts entirely, includ- blackouts and grayouts were happening much ing the G-suit contract with Berger Brothers. Courtesy of the David Clark Company, Inc. less frequently to pilots who wore the suit. The one with David Clark Company, however, Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection Pilots universally disliked all of the early G-suits but began to change their minds once the statistics began showing their combat performance, as measured in “kills” of enemy aircraft, improved while wearing the suits. In particular, a P-51 Mustang fighter group of the Eighth Air Force reported that pilots wearing anti-G suits shot down 67 enemy aircraft per 1,000 operational hours, compared with only 33 kills for other pilots. National Museum of the United States Air Force Collection David Clark to modify the pressurization valve to operate from much higher pressure, although details of its intended application were not immediately forthcoming. In fact, the modification was necessary to adapt the valve to use bleed air from the turbojet engines under development at GE.180 In due course, the military gave David Clark 107 permission to visit Muroc Army Air Field in California and witness test flights of both the Bell P-59A Airacomet and Lockheed P-80 Shooting Star. At the time, both airplanes werecontinued, although the company again began ramped up and the true cost of making the flying without the benefits of a G-suit. Richardmanufacturing undergarments for the civilian suit was known. The company cut a check Cornelius modified his valve to accept air frommarket (they were the “Sears Best” brassiere for $88,000 and returned the excess profits the highest stage of the compressor side of themanufacturer through the 1950s). Showing to the Navy, which, somewhat bewilderingly, General Electric I-16 and I-40 turbojets (laterhow the conduct of business differed during accepted it.179 produced as the J31 and J33).181the war years, when the end of 1945 came,the David Clark Company realized they had Even before V–J Day, there were some major At the request of the Navy, David Clark alsomade better than a 10 percent profit on a Navy changes in work for G-suits, although neither developed a set of full coveralls that containedG-suit contract. This was mostly because they David Clark nor Fred Moller knew what they bladders similar to the G-3. Naval Aviatorshad bid the per-suit cost before production were for. For instance, George Maison asked preferred the resulting Z-3 suit since they wore Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection The Lockheed P-80 program drove major changes to the way air was obtained to operate G-suits. The P-80 was the first operational jet fighter in the United States and formed the basis of the successful T-33 trainer that saw service for decades after World War II. Somehow, it seems that Lockheed was intimately involved with much of the evolution of G-suits and pressure suits. National Museum of the United States Air Force Collection Although the G-3 cutaway and G-4 coverall suits used similar bladder systems, there were some important differences. The bladders in the G-3 had a volume of 12.1 liters, while the G-4 used only 9.7 liters, primarily by reduc- ing the size of the abdominal bladder. Under identical conditions, this, along with eliminat- ing the leg lace adjustments, had the effect of108 reducing protection from 1.9-G for the G-3A to 1.5-G for the G-4. These changes made the G-4 more comfortable for the pilots, but in 1947, David Clark introduced the G-4A that used a larger abdominal bladder and provided 1.9-G of protection.183 Based on service trials on 25 fighter pilots during 1948 using both the G-3A and G-4A, the USAF determined the G-4A was more effective and more com- it instead of a normal flight suit, eliminating Joseph Ruseckas patterned the suit after the fortable. The USAF subsequently adopted one piece of clothing; it was also somewhat standard summer flight suit, and it came in the G-4A as its standard G-suit for the next cooler since only a single layer of cloth covered nine sizes without lace adjustments. While he several decades.184 the belly and legs. These were step-through was developing the patterns, Ruseckas inte- coveralls made of lightweight, inelastic, porous grated the parachute harness into the garment. By early 1948, the USAF was having second rayon cloth fitted with one abdominal and The Army bought a limited number of these thoughts about relying completely on the two leg zippers. At the David Clark Company, suits under the G-4 designation.182 David Clark Company for its G-suits, not Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionbecause of any failing with the company, getting ready to deploy to Korea and needed used an outer cover of 95 percent Nomex andbut because of competitive “sole source” the additional protection for its pilots.186 5 percent Kevlar cloth.188contracting concerns. Two other companiesexpressed interest: the Drybak Outdoor POSTWAR SUITS The CSU-15/P cutaway G-suit developed forClothing Company of Binghamton, NY, the Navy used pneumatic bladders located atand Warner Brothers of Bridgeport, CT. Shortly after the end of World War II, the the abdomen, left and right thigh, and leftThe USAF asked David Clark to assist both United States essentially halted attempts to and right calf. This suit differed from contem-companies in making prototype suits. When develop G-suits that were more effective than porary USAF suits by having different sizedthe USAF announced the winners of the the standard G-4A because the aircraft of the bladders, additional lacing adjustments, andfirst competitive procurement, David Clark era did not appear to need a better garment. a longer disconnect hose.189 A slightly revisedand Drybak shared the contracts. Eventually, Nevertheless, minor modifications resulted in version was designated CSU-15A/P. The offi-David Clark Company stopped producing the USAF and Navy using a variety of G-suits cial description of the CSU-15/P cutaway suitG-suits since there were fewer development through the end of the 20th century. did not differ much from the wartime G-3A:opportunities, concentrating instead on thedevelopment of pressure suits.185 The CSU-12/P coverall developed for the The CSU-15/P anti-G garment con- USAF used pneumatic bladders located at the sists of a fire-resistant Aramid clothGiven the head start that Wilbur Franks and abdomen, right and left thigh, and right and outer shell, which houses a bladder. Itthe Canadians had on developing G-suits, left calf. The bladder casings were fabricated of is cut away at the buttocks, groin, andit came as a crushing blow when the RCAFdecided in 1948 to purchase suits from David chloroprene-coated nylon and the outer cover of interwoven nylon and cotton. Laces at the knees. The outer shell has waist and leg entrance slide fasteners, six adjustment 109Clark Company. When Franks arrived in waist, thighs, and calves, covered by a Velcro lacing areas with lacing covers, and twoWorcester, David Clark showed them a new flap, allowed individual adjustment.187 easily detached leg pockets with slidesuit sewn by Joe Ruseckas. Franks asked fastener closures. The bladder system isfor some changes, including a larger belly The CSU-13/P was a cutaway G-suit devel- constructed of polyurethane-coated nylonbladder, and took the suit back to Toronto oped for the USAF that provided essentially cloth and covers the abdomen, thighs,for testing on the Canadian centrifuge. The the same protection as the CSU-12/P cover- and calves. The bladder system is fittedRCAF liaison at the Canadian Embassy in all. Bladders were located at the abdomen, left with a hose for connecting directly toWashington soon called David Clark and and right thigh, and left and right calf. The the aircraft anti-G system. This anti-Gordered 50 suits for immediate delivery bladder casings were fabricated of polyure- garment is available in six sizes.190and indicated an additional order would be thane-coated nylon taffeta and the outer coverforthcoming for an additional 250 suits (this of interwoven nylon and cotton. Laces at the On February 25, 1982, the Air Force andorder eventually got sidetracked, through the waist, thighs, and calves, covered by a Velcro Navy met at the Naval Air DevelopmentMutual Defense Assistance Program (MDAP) flap, allowed individual adjustment. The Center in Warminster, PA, to discuss stan-scheme, to another supplier). The RCAF was CSU-13A/P was a slightly revised version that dardizing on a single G-suit design to replace Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection the CSU-13/P and CSU-15/P, respectively. Corporation, Life Support International, Inc., Components of the ensemble included a Although the construction and placement of and Mustang Survival (Mustang Sportswear, lightweight helmet: low-profile, high-pressure the bladders differed somewhat in the two Ltd.). The CSU-13B/P replaced all earlier Air oxygen mask: an integrated full-coverage suits, the major differences were external. For Force and Navy G-suits as they reached the anti-G and immersion suit: and a specialized instance, the CSU-13/P leg closure zippers end of their service lives.192 Pilots commonly pressure/survival vest. The suit was tested closed in an upward direction, while the CSU- referred to the CSU-13B/P (and many other in a slightly modified General Dynamics 15/P used quick-release closures that separated G-suits) as “speed jeans.” F-16B (81-0816) at Edwards. The evaluators downward. The pocket configuration differed, felt the TFCS provided better protection as did the air supply attachment hose. The Air Although the CSU-13B/P was the standard- than the F-16/PBG and offered a significant Force had a large extra-long size that the Navy ized suit, several other G-suits were also used improvement over the standard-issue CSU- did not, while the Navy had a small, short size by the United States. For instance, the F-16/ 13B/P G-suit. However, the TFCS was bulkier for women that the Air Force did not. The Air PBG was developed by the Air Force Flight and more restrictive of movement than either Force rated the service life of the CSU-13/P at Test Center (AFFTC) at Edwards AFB specifi- American ensemble. Despite the TFCS vapor 12 months, but the Navy used the CSU-15/P cally for the F-16 Combined Test Force. The barrier, it was no cooler in the hot Edwards for 18 months.191 F-16/PBG featured the same G-suit bladder environment than the F-16/PBG. The TFCS coverage as the standard CSU-13B/P but helmet offered improved fields of view and During flight evaluations, pilots generally incorporated inflatable chest bladders into the greater noise attenuation. Notwithstanding the expressed a preference for the suit they upper portion of the ensemble to assist with advantages offered by the Swedish garment,110 were used to but felt that either suit was satisfactory. Based on the results of the tests, pressure breathing above 5-G. The suit used laces on the legs and torso to provide a snug the USAF did not procure it.194 the Department of Defense selected the CSU- fit. Below 5-G, the G-suit and chest bladders TLSS AND COMBAT EDGE 13/P as the common G-suit. The specific tri- functioned independently; above 5-G, the service model became the CSU-13B/P. This G-valve sent a proportionate pneumatic signal Officially, what came next are called “Anti-G cutaway suit used an Aramid cloth outer shell to activate the oxygen regulator to propor- Suits,” but, in reality, they are closer to partial- that contained polyurethane-coated nylon tionately increase breathing-gas output to the pressure suits. To increase pilot performance abdomen, thigh, and calf bladders. The outer chest bladders and the oxygen mask.193 under acceleration, modern G-suits use shell had waist and leg entrance slide fasteners, pressure-breathing masks and counter-pressure six lace adjustments with Velcro covers, and As a possible replacement for the F-16/PBG, vests in concert with lower-body G-suits. two detachable leg pockets with slide fastener from June 21 through August 24, 1989, the These suits also provide limited altitude pro- closures. The suit came in seven sizes: small F-16 CTF evaluated the Swedish Tactical tection up to 50,000 or 60,000 feet, although regular, small long, medium regular, medium Flight Combat Suit (TFCS). The TFCS was the lack of arm and hand protection limits long, large regular, large long, and large extra- an integrated life support ensemble designed to their use at high altitudes to a few minutes long. The suit was fabricated by a variety of provide protection from high-G, cold-water (truly a get-me-down capability). A brief manufacturers, including Aerotech Industry immersion, and temperature stress. description of the suits and their development Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • The McDonnell Douglas F-15 Eagle was the first of a newgeneration of highly maneuverable aircraft that drove thedevelopment of improved acceleration protection. Theseaircraft were capable of sustained +9-Gz maneuvers, wellbeyond the capabilities of the then-current, wartime-derivedG-suits. In addition, the F-15 had a thrust-to-weight ratioof greater than 1:1, making radical vertical maneuveringfeasible for the first time.U.S. Air Forceis presented here instead of in the partial-pressure suit chapter for consistency withwhat the Government calls the ensembles.During the early 1970s, Dr. Sidney Leverettand his colleagues at the USAF School ofAerospace Medicine recognized the need forbetter G-protection to accompany the verymaneuverable McDonnell Douglas F-15 Eagle 111and General Dynamics F-16 Fighting Falcon.These aircraft were capable of sustained 9-Gzmaneuvers, well beyond the capabilities of thethen-current, wartime-derived G-suits.195 Inresponse, the Air Force established the TacticalLife Support System (TLSS) program. Thiseffort had a wide range of research objectivesthat included “NBC” (nuclear, biological,chemical) protection, advanced anti-G protec-tion, moderate high-altitude (60,000 feet)protection, thermal-flash-protection goggles,aircrew cooling (via a liquid-cooling gar-ment), and on-board oxygen generation viamolecular-sieve apparatus (onboard oxygen
    • Chapter 3: Acceleration Protection generation system, or OBOGS). Meeting all generally positive results. Four pilots tested fully integrated pressure-vest/torso garment of the requirements involved the development the fully integrated TLSS prototype system (upper-pressure garment, or UPG), TLSS of several new pieces of equipment, including (including OBOGS) in the front seat of the extended-coverage G-suit (lower-pressure a new breathing regulator that could interface F-15B during 26 flights that included high- garment, LPG), and a modified CRU-73 with the OBOGS and a new type of G-valve to altitude, air-to-air, and air-to-ground roles. regulator. Ensemble II included the TLSS operate the G-suit and counter-pressure vest.196 A simplified system that used a modified component pressure vest/torso garment, CRU-73 breathing oxygen regulator and standard CSU-13B/P G-suit, and modified Instead of a competitive development effort, the existing G-valve was tested in the CRU-73 regulator. The component pressure the Government formed a team that included back seat of an F-16B by 4 pilots during vest did not provide complete coverage of the various USAF laboratories, the Canadian 24 flights in the air-to-air mode. In addition, torso like the fully integrated pressure vest. Defence and Civil Institute of Environmental the suit successfully survived an explosive Ensemble III used an extended pressure-vest/ Medicine (DCIEM), Boeing, and Gentex. decompression at 60,000 feet in the Brooks torso garment, CSU-13B/P G-suit, and a As with most ambitious programs, TLSS ran AFB altitude chamber. Despite its seeming modified CRU-73 regulator. The extended behind schedule and over budget, and it even- success, the Air Force and Congress ulti- pressure vest provided more coverage than the tually dropped some of its original objectives. mately deemed TLSS too expensive to component pressure vest, but not as much as produce in large numbers. the fully integrated pressure vest. Ensemble The DCIEM was responsible for design of IV featured the extended pressure vest/ the TLSS G-suit and constructed a garment However, the relative success of the simplified torso garment, a full-coverage G-suit, and a112 that included a lower-body G-suit and a counter-pressure vest to aid with pressure system tested in the F-16B resulted in the Air Force redirecting the program during 1988 modified CRU-73 regulator. The full coverage G-suit used bladders that completely covered breathing. The suit featured full NBC and toward improving G-protection and dropping the thighs and calves instead of the separate thermal flash-protection goggles. Canada had many of the other original goals. In part, bladders in the CSU-13B/P that only applied earlier identified the need for suitable high- this was the result of a significant increase counter-pressure to the sides of the limb. altitude protection for aircrews of the new in gravity-induced loss of consciousness Ensemble V used the extended pressure vest/ high performance fighter it was planning to (G-LOC) accidents in the F-16. torso garment, full-coverage G-suit, and an acquire. However, when that aircraft turned experimental (NGL) pressure regulator from out to be the McDonnell Douglas CF-18 The USAF School of Aerospace Medicine the United Kingdom that provided the same Hornet, which was limited to altitudes around undertook an extensive series of centrifuge pressures as the CRU-73 at lower breathing 50,000 feet, the need for the suit largely went studies with several combinations of resistance. All of the ensembles used the TLSS away. Nevertheless, Canada continued to par- components from the TLSS and other sources helmet and oxygen mask. ticipate in the TLSS program until the end. to define a workable combination that could be fielded quickly at a reasonable cost. Five Based on the results of tests on the Brooks The TLSS was flight-tested at Edwards during different ensembles were ultimately selected human centrifuge, Ensemble III seemed 1986–87 using an F-15B and F-16B with for further testing. Ensemble I used the TLSS to offer the best compromise between Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionprotection and comfort. This was also one Physiologists differentiate between pressure G-valve; therefore, the PBG pressure level alsoof the least expensive options to implement. breathing for G (PBG) and pressure breathing varies as a ramp function in response to higherThis configuration became the basis for the for altitude (PBA) although the differences acceleration levels.200Combined Advanced Technology Enhanced are so subtle as to be lost on laymen. In theDesign G-Ensemble, which, became bet- PBG mode, the same pressure that is applied During the early 1980s, the L-1 anti-Gter known as Combat Edge. The TLSS to the vest bladders is supplied to the pilot’s straining maneuver replaced the originalhelmet was replaced with the already fielded respiratory system through the oxygen mask. M-1 developed by the Mayo Clinic duringlightweight HGU-55/P. However, the tests Combat Edge obtains two beneficial effects World War II. The L-1 maneuver combinesconclusively demonstrated the full-coverage from this action. The most obvious benefit is a regular, 3-second strain (Valsalva) against aG-suits significantly increased acceleration that the pilot can breathe during PBG, but closed glottis, interrupted with rapid exhala-protection, so their development was con- in addition, since the system is squeezing the tion and inhalation while tensing of all majortinued as the Advanced Technology Anti-G pilot’s chest from the inside as well as the muscles of the abdomen, arms, and legs.Suit (ATAGS).197 Various configurations of outside, it denies even more volume for blood Properly executed, it provides an average pilotextended coverage G-trousers were designed pooling and more blood is pushed toward approximately 1.5-G protection. This is aboutand tested, and some of the designs pro- the head. the same as the standard G-suit, so combinedvided almost 100-percent coverage and even the suit and straining maneuver provideincluded booties to cover the feet.198 The pressure level of the Combat Edge about 3-G protection. The M-1 maneuver PBG breathing air supply is controlled by was essentially the same but against a partiallyFor all intents, Combat Edge is a descriptionof pressure breathing, and the components the breathing air regulator, which in turn, is controlled by the G-valve. An important open glottis, causing the pilot to audibly grunt during the strain, resulting in lower intra- 113of Combat Edge act in unison to sense and system feature is the interlock between thoracic pressures. The Navy teaches a slightrespond to high-G conditions. The G-valve the trousers and vest that is created by this variation of the L-1 called the Hook Maneu-sends a signal to the oxygen regulator to method of control. The system design ensures ver in which the pilots initiate the strain phaseincrease mask pressure up to 1.2 psi above that the G-trousers are fully pressurized and by saying, “hook” as they begin to strain. Thisambient. This same pressure is routed to the inflated before the counter-pressure vest helps ensure a completely closed glottis.201 Inoccipital bladder in the back of the helmet, can begin to fill and apply pressure. If this either case, the signal to commence strainingcausing it to inflate and push the pilot’s face interlock did not exist, and the counter- is the beginning inflation of the bladders, feltinto the oxygen mask. This same pressure pressure vest filled first, the blood from the first in the G-suit.is also sent to the counter-pressure vest to legs and abdomen would be trapped andbalance the breathing pressure supplied to the could not rise toward the pilot’s head. The While Combat Edge does not replace thelungs. Ultimately, Combat Edge maintains G-trouser pressure level is several times straining maneuver, it significantly reducespressure in the pilot’s chest cavity to help the higher than the PBG pressure level. The the effort required to execute it. A commonheart pump blood to the eyes and brain while output pressure of the PBG regulator varies misconception is that fighter pilots tendinhibiting the downward blood flow.199 in response to the output pressure of the to make long sweeping turns that produce Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection medium-to-high acceleration levels that are The initial USAF Combat Edge ensemble The CSU-20/P is similar to the CSU-13B/P maintained for a relatively long time. In fact, consisted of the CSU-17/P counter-pressure with a 40-percent increase in leg- and abdo- this is seldom the case. Air combat maneuver- vest, CSU-13B/P G-suit, HGU-55/P helmet men-bladder coverage. It has a flame-resistant ing (ACM) is a constantly changing accelera- with an occipital bladder, and MBU-20/P cloth outer shell with waist and inner-leg slide tion environment, often consisting of a zigzag oxygen mask. The flight-test community fasteners, adjustment lacing with covers, and pattern that generates anywhere between evaluated the first prototypes at Edwards leg pockets with slide-fastener closures. The +5-Gz and +9-Gz on each alteration. Except in 1988, and formal testing took place in CSU-21/P vest has a flame-resistant cloth for the straining action, Combat Edge func- 1990 using F-15s and F-16s. Operational outer shell with a front slide-fastener closure tions automatically. The bladders sequentially test and evaluation of the ensemble was for easy donning and doffing and laces to inflate and deflate, the mask tightens and loos- completed in 1991, and all F-15 and allow sufficient adjustment for correct fit.206 ens, and the pilot is allowed to concentrate on F-16 aircraft were modified, mostly with flying the airplane. At the end of a mission, new G-valves, to accept the equipment by Somewhat before the development of the pilot who has flown with Combat Edge is mid-1995. New production aircraft after Combat Edge, McDonnell Douglas considerably less fatigued than one flying the that date have the equipment installed at undertook a program called Atlantis Warrior, same mission in a conventional G-suit.202 the factory. led by Dr. D. Lambert, which was conceived around a hydrostatic suit containing 6 liters Despite its improved acceleration protec- The Navy was not completely happy with of water. It was conceptually similar to what tion, the Combat Edge counter-pressure vest the Combat Edge ensemble. Instead of the Bill Franks fabricated during World War II. A114 has a significant drawback: it is hot to wear. The original TLSS-integrated flight suit used CSU-15B/P G-suit, the Navy selected the Canadian-developed Sustained Tolerance prototype was tested on a human centrifuge, where it reportedly performed well, and where a liquid-cooling system composed of tub- for Increased G extended-coverage G-trouser. it demonstrated the ability for the pilot to ing threaded inside the bladder layer. This The Navy Combat Edge ensemble is des- talk under +10-Gz acceleration loads for up liquid-cooling system was not carried forward ignated A/P22P-16 and provides enhanced to 3 minutes and maintain consciousness at as part of Combat Edge because it was not acceleration protection between +4- and +12-Gz.207 The suit underwent comparative logistically supportable, leaving the Combat +9-Gz to an altitude of 50,000 feet. Below human prolonged high-G exposure testing Edge vest somewhat uncomfortable in some +4-G, the ensemble provides the same during 1996 at Wright-Patterson AFB. These climates. Nevertheless, liquid-cooling systems level of protection as the CSU-15B/P. The tests showed a higher number of tolerated continue to have supporters, and the Euro- Navy uses Combat Edge only in the 5-9-Gz peaks compared to the other suits, fighter Typhoon uses one.203 Recently, the Air F/A-18 fighter. The ensemble consists of and subjects did not suffer any documented Force authorized use of the Combat Edge the CSU-20/P cutaway anti-G garment, episodes of G-LOC.208 Despite its clinical system without the counter-pressure vest, the CSU-21/P counter-pressure vest with a success, Atlantis Warrior was not produced. justification being enough flight-hours have chest-mounted CRU-103/P G-compensated been accumulated to show that the wearer oxygen breathing regulator, HGU-68/P Interestingly, the German Luftwaffe finally would not be in danger.204 helmet, and MBU-24/P oxygen mask.205 fielded a hydrostatic G-suit, 60 years after Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionit initially developed, and rejected, the con- Force. With this ensemble, pilots were able at the onset of acceleration. Some of thecept. The Libelle G-Multiplus, developed by to withstand accelerations between –0.9-Gz subjects reported they had to be much moreAutoflug Libelle GmbH (a joint venture of and +10.4-Gz and at a maximum onset of conscious of the maneuvering of the aircraftLife Support Systems AG of Switzerland and +5-G per second with no apparent decrease to add their straining effort at the properAutoflug GmbH of Germany), is a full-body in situational awareness.210 During 1998, moment. Researchers determined the trainingG-suit that uses hydrostatic rather than pneu- the Swiss and German air forces evaluated requirements for optimum use of the systemmatic pressure. The suit looks much like what the suit in a direct comparison between the were almost the exact opposite to those ofHarold Lamport at Yale and Helen Lester and Libelle suit and the standard CSU-13B/P Combat Edge. Instead of straining (whichDavid C. Spooner at General Electric devel- pneumatic suit using 10 subjects (8 fighter will cause at least an interruption in normaloped in 1943, with the primary difference pilots, 1 M.D., and 1 civilian pilot). At that breathing), the trainee for the Libelle system isbeing the fact that the capstan tubes are fluid point, the Libelle consisted of a seat cushion encouraged to breathe as normally as possible.filled instead of air filled. that provided G-proportional pretensioning This promotes a greater ability to speak of the suit to allow for optimal efficacy of during the high-G maneuver. If the Libelle“Libelle” is German for “dragonfly,” because the hydrostatic capstan-like principle. The system were to be adopted, the Libelle trainingthe suit is based on the same principles that suit performed reliably and did not cause regimen would also have to be put in place.protect a dragonfly from the 30-G accelera- any G-LOC in a passive-acceleration profiletions the insect generates in flight. The suit and in simulated air-combat maneuvering. Beginning in March 2000, the Libelle wasuses 0.3 gallons of liquid to exert counter- The Libelle system achieved a relaxed evaluated by the USAF on centrifuges atpressure during acceleration. When accelera-tion forces push blood toward the lower part G-tolerance of +7.1-Gz compared to +6.7-Gz for the CSU-13B/P—a statistically irrelevant Holloman AFB and Brooks AFB and during flight demonstrations at the USAF Test Pilot 115of the body, it also pushes the liquid inside difference. Problems with the suit primarily School at Edwards AFB. The evaluation didthe suit in the same direction, providing a were the very tight fit and the need for a not exceed +9-Gz in either the centrifuge orcounter-pressure that is automatically adjusted different straining maneuver.211 flight tests. In general, the evaluation teamby the G-load itself. The suit uses fluid-filled had a favorable opinion of the Libelle, whichchannels traversing the arms, torso, and legs Combat Edge pilots need to perform a offered certain advantages over the Combatto tension its snug-fitting fabric. The suit is an straining maneuver as their contribution Edge suit.212 In the end however, the USAFautonomous, stand-alone system that does not to the successful system performance. did not pursue the Libelle system. Dr. Olarequire air or power from the aircraft.209 The signal to commence straining is the Eiken and his team also evaluated the suit beginning inflation of the bladders, felt first on the human centrifuge in Sweden in 2002.The suit was tested on the centrifuge at in the G-trousers. Combat Edge-trained They studied three pilots in the Saab JAS-39the German Air Force Institute of Aviation aircrew who have flown the “automatic” Gripen extended-coverage G-suit and com-Medicine in Königsbrück and in more than Libelle suits note that this physical signal is pared it to the tolerance afforded by use of the200 flights in Pilatus PC-7 turboprop trainers missing because hydrostatic operation does Libelle suit. The results showed a G-toleranceand a Learjet belonging to the Swiss Air not offer the sensation of the G-suit inflating of +6.3-Gz with the Libelle suit and +9.0-Gz Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection with the standard pneumatic suit, a result CSU-23/P are on the right side of the suit, left-hand connections. Three test conditions seemingly favoring the older technology.213 explaining why it is only compatible with the were evaluated, one using a standard left-hand Nevertheless, on January 31, 2005, the Libelle Lockheed Martin F-22 Raptor. On June 30, CSU-13B/P suit, one using the modified right- G-Multiplus became operational in Typhoons 2008, the Air Force awarded the latest con- hand CSU-15B/P suit, and the last using the from Jagdgeschwader 73 of the German Air tract for 150 ATAGS CSU-23/P G-trousers to CSU-23/P suit. For each of these, the G-suit Force at Laage Air Base. Vinyl Technology, Inc. of Monrovia, CA, for was inflated according to the standard aircraft $741,501, or approximately $4,943 each.217 A schedule. Pressure breathing began at +4Gz, ATAGS AND THE F-22 similar ATAGS suit, designated CSU-22/P, has with a linear increase in pressure of 12 mm interfaces on the left side that are compatible Hg per G to a maximum of 60 mm Hg at As the TLSS program morphed into Combat with the F-15, F-16, and F/A-18.218 +9Gz. The maximum possible time for each Edge, human centrifuge tests continued condition was 90 seconds. Unsurprisingly, the to show that full-coverage G-suits offered Having a unique G-suit for the F-22 posed researchers decided it did not matter which significantly increased acceleration protection, a variety of logistical problems for the Air side the G-suit hose connection was on. so the Air Force continued to develop the Force, so the Air Combat Command asked garments as the Advanced Technology Anti-G the Armstrong Laboratory to evaluate if the The researchers did find, however, that the Suit (ATAGS).214 Various configurations of CSU-23/P could be replaced by the standard CSU-23/P provided better protection under extended coverage G-trousers were designed CSU-15B/P from Combat Edge. Of course, some conditions than the CSU-15B/P. For and tested. Some of the designs provided the F-22 would still have its interface connec- instance, the CSU-23/P demonstrated a lower116 almost 100-percent coverage and even included booties to cover the feet.215 tions on the right side of the cockpit, mean- ing either the CSU-13B/P would need to be discomfort level and lower heart rate during gradual acceleration. The suit also allowed modified (negating the point of the exercise) the pilot to endure constant acceleration The final configuration of the G-suit was des- or some method would need to be found of for longer periods, and a lower heart rate ignated CSU-23/P but is generally still called connecting a left-handed G-suit to a right- during rapid acceleration. The test subjects ATAGS. As a stand-alone garment, ATAGS handed airplane.219 also tended to rate the CSU-23/P better provides a 60-percent increase in aircrew than the CSU-15B/P in overall G-protection endurance. Combined with Combat Edge, Since there are no two-seat F-22s, the Air and fatigue level after G-exposure.220 it increases aircrew endurance by 350 percent Force decided to use a two-seat F-15B for the over the standard G-suit. Unlike other G-suits, evaluations. This presented a problem since Instead of joining ATAGS, the Navy initi- ATAGS completely envelops the legs and but- the CSU-13B/P is configured to work correctly ated a parallel program called the Enhanced tocks and rides lower on the torso so that it in an F-15. The solution was to fabricate nine Anti-G Lower Ensemble (EAGLE) to develop does not push against the chest.216 CSU-13B/P suits with the inlet hose moved an improved G-suit. There were significant to the right-hand side. A hose was developed differences between ATAGS and EAGLE. The Oddly, unlike all previous G-suits for the that routed the air across the ejection seat to ATAGS CSU-23/P had a smaller abdominal past 50 years, the air connections for the interface the nonstandard suits with standard bladder than the standard CSU-13B/P G-suit Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protectionand the leg bladders completely enclosedthe legs and feet. The EAGLE CSU-20/Pabdominal bladder was the same size as theCSU-13B/P, and the leg bladders completelyenclosed and pressurized the upper and lowerlegs down to the boot, but the knees and feetwere unprotected. EAGLE also included aCSU-21/P counter-pressure vest, MBU-24/Ppressure breathing mask (an MBU-20/P withNavy communications equipment), and anupgraded HGU-68/P helmet with a blad-der. The HGU-68/P helmet featured a muchimproved, lightweight, and easily adjustedexternal visor that had been rocket-sled testedat the Hurricane Mesa facility to resist ejectionwindblast forces in excess of 600 knots.221In 1993, the Air Force Armstrong Laboratorycompared the performance of the ATAGSand EAGLE G-trousers. The human centri- 117fuge tests began at +3-Gz for 15 seconds andincreased to a maximum of +9-Gz until physi-ological termination criteria were exceeded orThe retrograde inflation anti-G suit (RIAGS) was a modernincarnation of the 1943 progressive arterial occlusion suit(PAOS) and featured a set of bladders that progressivelyinflated from the ankles to the abdomen. The goal wasto develop a G-suit that offered a significant increasein protection over the CSU-13B/P G-suit that was inwidespread service.Courtesy of the David Clark Company, Inc. Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection the 15-second limit was reached, whichever The RIAGS leggings contained a set of urethane-coated nylon came first. The tests found that both sets of bladders on the legs and abdomen that could be inflated to trousers provided better protection than the 12 psi. Modern fabrication techniques resulted in bladders standard CSU-13B/P, although they each had that were considerably less bulky than those used on the disadvantages such as increased heat load and 1943 suit. reduced mobility. The researchers found that, statistically, the ATAGS with pressure socks Courtesy of the David Clark Company, Inc. provided better protection than the EAGLE, which did not include pressure socks. The G-suit that could be tested in three configura- test subjects also reported less fatigue with tions: the basic abdomen and leg trousers, the ATAGS.222 those with arm and/or leg arterial-occlusion cuffs, and any combination of those with a set REDISCOVERING THE PROGRESSIVE of capstan sleeves. Modified medium-long, ARTERIAL OCCLUSION SUIT blue Nomex CWU-27/P flyers coveralls were also fabricated for each of these combinations. David Clark and Earl Wood’s 1943 progres- The urethane-coated nylon bladders were sive arterial occlusion suit (PAOS) was briefly ultrasonically sealed, resulting in a lighter- resurrected in 1989, when Lloyd D. Tripp, Jr., weight and less bulky suit than had been fab-118 and researchers from Systems Research Labo- ratories and the Crew Systems Directorate of ricated in 1943. The basic G-suit consisted of bladders located on the legs and abdomen that the Biodynamics & Biocommunications Divi- could be inflated to 12 psi. The arm and leg sion at Wright-Patterson AFB began looking cuffs could also operate at 12 psi, while the 5:1 for more effective G-suits. According to the ratio capstans on the sleeves operated at 30 psi researchers, “the original PAOS design was res- to provide 6 psi of skin pressure.225 urrected because of the G-induced loss of con- sciousness problem in USAF aircraft and the The suit was tested on the Dynamic Environ- suit’s apparent improvement in G-protection that inflated to 12 psi, and the other used a ment Simulator, a 19-foot radius human cen- over the standard CSU-13B/P G-suit.”223 set of capstans and interdigitizing laces that trifuge at Wright-Patterson AFB. The results inflated to 30 psi.224 showed that most of the subjects complained The Retrograde Inflation Anti-G suit (RIAGS) about the arterial occlusion cuffs, reporting used a series of bladders that progressively Fittingly, the Systems Research Laboratories tingling hands and fingers, decreased dexterity inflated from the ankles to the abdomen. issued a purchase order to the David Clark of the hands, and in some cases, pain. The use In addition, two different sets of arms were Company for the fabrication of the experi- of the capstan sleeves provided better protec- developed: one used arterial occlusion cuffs mental suit. The effort included fabricating a tion than the standard CSU-13B/P G-suit, Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 3: Acceleration Protection To cover the RIAGS leggings, David Clark Company SUMMARY fabricated a modified set of CWU-27/P flyers coveralls in blue Nomex. Although the suit performed well, by the time The past decade has seen a resurgence of the RIAGS tests were completed, the Armstrong Laboratory acceleration research, aimed primarily at at Brooks AFB was well along with the development of the future generations of highly maneuverable Advanced Technology Anti-G Suit (ATAGS) and the RIAGS fifth-generation fighters. These efforts are concept was dropped. well beyond the scope of this book. Courtesy of the David Clark Company, Inc. but the arterial cuffs provided no meaningful increase in protection. When the PAOS suit had been tested at the Mayo Clinic in 1943, the test durations were very short, and the use of arterial cuffs provided a meaningful, short- duration increase in acceleration protection. However, the modern tests ran much longer and showed the cuff actually decremented protection compared to either not having any arm protection or to using the capstan sleeves. 119 By the time the RIAGS tests were completed, the Armstrong Laboratory at Brooks AFB was well along with the development of ATAGS, and the RIAGS concept was dropped.226Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • 4
    • Chapter 4: Partial-Pressure Suits4: Partial-Pressure SuitsUltimately, the Army’s wartime effort to suit (PPS) and full-pressure suit (FPS) are not allow the pilot to descend to a safe altitude,develop a full-pressure suit proved unsuccess- particularly descriptive but through common either suit works satisfactorily. It is a differentful. However, the performance of airplanes, usage have become the accepted nomenclature story for an explosive decompression. Mostparticularly a new generation of fighters for the garments. As ultimately defined, a par- operational scenarios from the late 1940sequipped with turbojet engines and a series tial-pressure suit protects its occupant through show a pilot wearing an unpressurized suit,of rocket-powered research aircraft developed the application of mechanical pressure against mostly to increase comfort and lessen thelate in the war, continued to increase. The the skin, all of which may or may not be cov- effort necessary to fly the airplane. Because itadvent of the workable pressurized cockpit ered (the head, hands, and feet were often bare is a relatively tight-fitting garment, even anlargely relegated the pressure suit to that of in early suits). The friction of the fabric on the unpressurized partial-pressure suit providesan emergency device, much like a parachute. skin offers resistance to motion, and irregulari- some protection during a rapid decompres-What was needed was a garment that offered ties in body contour result in unequal distribu- sion. Oddly, although a full-pressure suitprotection in the event of a loss of cabin pres- tion of pressure, giving both pressure points would seem to be the garment of choice insure. At one end of this spectrum was a suitthat would protect against an engine flameout, and unpressurized areas. Pressure breathing is a key part of any partial-pressure suit, which such an event, an unpressurized full-pressure suit offers little protection against a rapid 121which would result in a slow decompression, provides sufficient counter-pressure to allow decompression since it is loose-fitting. To offersince the cabin structure would remain intact exhalation at extreme altitudes. On the other any protection, a full-pressure suit needs to bebut the source of pressurization would be hand, the full-pressure suit offers protection by pressurized to at least a low level all the time.2lost. At the other end of the spectrum was a applying gas pressure against the skin, creat-suit that would protect against the explosive ing a mini artificial environment in which the PRESSURE BREATHINGdecompression that would result from the loss occupant can breathe, more or less, normally.1of the canopy or a similar structural failure. In the decade after the Europeans tradedIn response, the Army began seeking an emer- For a slow decompression, as might happen altitude records, Wiley Post’s prediction thatgency partial-pressure suit. following a flameout of a jet engine, either a aircraft would routinely fly at high altitudes partial- or full-pressure suit provides adequate came true. As this was taking place, physiolo-All previous American pressure-suit-develop- protection since the pilot has time to close gists realized that standard demand-typement work had concentrated on the concept his helmet and pressurize the suit. Ultimately, oxygen systems were not adequate forof a full-pressure suit. As David Clark, the of course, the full-pressure suit provides bet- extended flights above 30,000 feet. In theman, once opined, the terms partial-pressure ter protection, but if the goal is simply to demand-type system, oxygen only flows Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 4: Partial-Pressure Suits when a person inhales, and then only as Laboratory. Pharo Gagge (pronounced like and coined the term “oximeter.” Initially used much as is required to fill the lungs. Even baggy) earned his doctorate in physics at to determine oxygen saturation in aviators, by on pure oxygen at 30,000 feet, the law of Yale University in 1933 and joined the John 1948 a similar device was used to control anox- partial pressures results in a severe decline B. Pierce Laboratory in New Haven, CT. emia during surgical anesthesia. The Waters in alveolar oxygen saturation levels. At The laboratory, an independent research Company X-350 Oximeter, based on work 43,000 feet, the alveolar oxygen saturation institute affiliated with Yale, was founded in by Earl H. Wood at the Mayo Clinic, was the produced by ambient pressure can sustain 1933 across the street from the Yale School first oximeter to give absolute readings of oxy- consciousness for only a short period.3 of Medicine. The laboratory still exists and gen saturation without prior adjustment to a is devoted to “studying the ways biological known concentration. Similar oximeters were During the mid-19th century in Germany, systems interact with their environment.”5 used during cardiac surgery at the Mayo Clinic. Dr. Louis Waldenburg (1837–1881) carried In 1950, Gagge became Chief of Medical out the first experiments on breathing at high Research for the USAF Surgeon General, and The pressure-delivery device used during these pressures, generally called pressure breathing from 1955 through 1960, he was Deputy experiments was a compensated metabolism (more recently called positive pressure breath- Commander and then Commander of the apparatus designed by Gagge when he was at ing, or PPB), in an attempt to cure various Air Force Office of Scientific Research. Gagge the Pierce Laboratory. The tests demonstrated respiratory diseases. From his, and similar, retired from the USAF in 1963 and returned that human subjects using pressure breathing experiments came pneumotherapy, using to the Pierce Laboratory. were able to survive and function effectively pressure-breathing devices that were often at higher altitude. In fact, Gagge was able to122 called Waldenburg apparatuses. The early researchers used intermittent pressure breath- Kearby was the project officer for the wartime full-pressure suit development effort. In early ascend to 46,000 feet in an altitude chamber and retain reasonable effectiveness. However, ing at 22 mm Hg to expand the lungs. It is December 1941, Kearby asked Gagge what by March 1942, Gagge realized that the com- probable that, under certain conditions, such effect “supercharging” air into the lungs would pensated metabolism apparatus, as a means of breathing may have given some benefit to have on human performance at high altitude, supplying pressure breathing, was incapable victims of pneumonia or various respiratory believing this might offer an emergency pro- of further improvement.7 diseases, but too little was known about the cedure in case of damage to a full-pressure physiology involved, and the whole matter suit during a chamber test. Researchers used Standard oxygen masks—all derived from the fell into disrepute and was forgotten.4 breathing pressures of 4, 7, and 11 mm Hg in BLB concept originally pioneered at the Mayo the altitude chamber, and an oximeter mea- Clinic—did not work well as pressure-delivery In the United States, the Aero Medical sured a noted increase in arterial saturation.6 devices since increased oxygen flow simply Laboratory at Wright Field led Army research Oximetry is the measurement of arterial oxy- pushed the masks away from the face, regard- into aviation medicine. In November 1941, gen saturation by transmitting light through less of how tightly they were cinched around A. Pharo Gagge (1908–1993) reported for a translucent area of a patient, usually the ear- the head. A full-face mask, then an integrated active duty, working for Capt. John G. Kearby lobe. In 1939, British scientist Glen Millikan mask-helmet, eventually addressed this prob- in the Miscellaneous Unit of the Aero Medical developed the lightweight ear-oxygen meter lem and forced oxygen into the lungs. As it Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 4: Partial-Pressure Suitsturned out, this was the easier part of the outside of the chest to prevent lung damage pressure breathing with a vest as without it. Aproblem. Now, the pilot had to exhale, and and to make exhaling easier. In response, number of researchers attempted to define thewithout external pressure on his chest (which Dr. Alvan L. Barach (1895–1977), a physician factors responsible for lung collapse and even-normally comes from the ambient air pres- affiliated with Columbia University in New tually traced the phenomenon to a diminishedsure), this proved difficult. Instead of breath- York who had long specialized in pulmonary cardiac output caused by excessive pooling ofing normally, the pilot had to forcibly exhale, research, developed a counter-pressure vest. blood in the veins. The counter-pressure vestan action that is not instinctive and takes Nominally, the vest maintained the same pres- reduced pooling in the abdomen, and experi-more concentration that one would expect. In sure as the oxygen a pilot was breathing. As ments using inflatable trousers (essentially,addition, the lungs are not particularly power- the pilot inhaled, the vest deflated, and when G-suits) prevented pooling in the legs—thisful, as evidenced by the amount of effort it the pilot exhaled, the vest inflated, forcing allowed somewhat higher pressures. Henrytakes to blow up a balloon. Researchers found the chest inward and helping the pilot exhale. Bazett ascended to 51,500 feet for 30 min-that many subjects suffered from collapsed Similar vests were developed by Bazett, utes using an inflatable vest and trousers, andlungs while pressure breathing. It was a per- Dr. Walter M. Boothby at the Mayo Clinic, others found it possible to get to 55,000 feetplexing problem. and Professor John D. Akerman at the Uni- using the technique. Ultimately, researchers versity of Minnesota. Further, it was clear to determined this was the maximum altitudeIn January 1942, the National Research at least Barach and Bazett that if pilots were to that could safely be supported using a pressure-Council Committee on Aviation Medicine avoid serious disturbances in the circulatory breathing mask and counter-pressure vest.11visited the Aero Medical Laboratory to eval- system, it would be necessary to apply similaruate pressure breathing. Dr. Eugene F. DuBois(1882–1959) was chairman, and the com- pressures to the abdomen and limbs.9 Work continued to improve pressure-breathing equipment. In June 1942, the J.H. Emerson 123mittee included Dr. John F. Fulton of Yale Under the direction of Kearby, one of the Company in Cambridge, MA, specialistsUniversity and Dr. Henry C. Bazett (1885– companies developing full-pressure suits, B.F. in medical respiratory equipment and iron1950) of the University of Pennsylvania. Goodrich, fabricated a rubber bladder and lungs, developed a modified A-12 demandShowing that it is a small world, Pharo Gagge rigid outer vest to place around the chest wall. regulator that supported pressure breathing.and Bazett had previously worked together Essentially, this used the same principle as At the same time, Capt. Francis E. Randallat the Banting and Best Institute for Medical the vests developed by Barach and the others. at the Aero Medical Laboratory used anthro-Research in Toronto. The committee was Pharo Gagge used this vest for the first time in pomorphic facial measurements to develop aimpressed by the results of the pressure- March 1942, and the vest supported the chest mask that allowed pressure breathing whilebreathing experiments.8 sufficiently to allow exhaling against pressures remaining relatively comfortable to the wearer. of 30 to 40 mm Hg (enough to usefully sur- The prototype Randall mask was designatedHowever, it was immediately obvious to the vive at 50,000 feet for about 30 minutes).10 Type XA-13, and the Army requested furthercommittee that if it was going to use more development from the Mine Safety Appliancesthan 15 mm Hg pressure, it would be neces- However, physiologists discovered that lung Company in Pittsburgh, PA (a company withsary to apply a balancing pressure on the collapse ensued almost as readily when a long history of research on mining breathing Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 4: Partial-Pressure Suits systems). In November 1942, Randy Lovelace pressure breathing at 48,000 feet in the aspects of flying. At the same time that Bazett tested the Emerson valve and A-13 mask Wright Field altitude chamber.14 Pharo Gagge was working with the British, Drury at USC aboard a B-17E flown by Boeing test pilots later stated that “the doubting Thomases conducted a separate evaluation of a breathing Al C. Reed and Jim Frasier to 43,600 feet. still remained, as several even questioned vest combined with inflatable trousers. He Using data from the flight, Bradford Holmes the accuracy of our altimeters and even the was unable to demonstrate any significant gain of the Pioneer Bendix Company simplified the mercury barometers. All calibrations later in pressure tolerance and dismissed the con- Emerson regulator so that a single knob con- proved accurate.”15 cept as impractical. This soon became trolled the exhalation pressure and diaphragm the USAAF position, the successes by the pressure. Lovelace and Lockheed test pilot During the conference, Bazett used an RAF notwithstanding.17 Joe Towle tested an early Holmes pressure- ensemble consisting of a pressure-breathing breathing regulator in a two-seat Lockheed mask, a pressure vest, and an early G-suit to By the end of 1943, the Aero Medical P-38 Lightning to 45,000 feet over Burbank, demonstrate the altitude gains possible while Laboratory and its contractors had largely CA, in April 1943.12 pressure breathing at 35 mm Hg. However, abandoned efforts to gain altitude using the ensemble did not provide sufficient coun- counter-pressure clothing, settling instead for In May 1943, the Joint Services Pressure ter-pressure, and Bazett had to discontinue the slightly lower altitudes afforded by pressure Breathing Conference convened at Wright the experiment without demonstrating a con- breathing alone. The 28th Photographic Field to discuss the status of various experi- vincing gain in altitude over pressure breath- Reconnaissance Squadron at Peterson Field, ments. By this time, several leading authorities ing without any counter-pressure clothing. CO, conducted operational flight tests of124 in the field of respiration had expressed con- siderable disbelief that pressure breathing pro- Nevertheless, Bazett stated that he thought it possible to use a similar ensemble for short the pressure-demand oxygen system in early October 1943. Based on the encouraging vided any benefit, especially at the relatively fights up to 55,000 feet. The RAF seemed results of these tests, the USAAF issued low pressures used by the Army. For instance, particularly interested in pressure breathing contracts to Mine Safety for 4,000 Type A-13 Dr. Douglas R. Drury at USC believed that since it would allow a relatively quick method masks packaged with Type A-14A regulators pressure breathing afforded protection only of improving the operational altitude of recon- supplied by the ARO Corporation. The 14th when used at very high levels. He thought naissance aircraft. Bazett worked with the Photographic Reconnaissance Squadron flew the enthusiasm for pressure breathing and Royal Aircraft Establishment at Farnborough, the first operational combat mission with for increased altitude performance resulted England, to develop a pressure-breathing the new equipment in February 1944, using from “high motivation rather than improved apparatus that the British quickly pressed into Supermarine Spitfire PR.XI aircraft.18 By physiology.”13 Later, this opinion would prove service. The RAF would refine this basic tech- late 1944, the Biophysics Branch of the Aero substantially correct. nology for the next six decades.16 Medical Laboratory, under the leadership of Pharo Gagge, had equipped all Lockheed Despite the contrary opinions expressed dur- Pharo Gagge, on the other hand, was gener- F-5 Lightning and Boeing F-13 Superfortress ing the conference, Capt. Norman Molomut ally opposed to counter-pressure clothing, reconnaissance aircraft with the Type A-13 of the Aero Medical Laboratory demonstrated feeling that it overly complicated the military masks and Type A-14A regulators.19 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 4: Partial-Pressure Suits The United States operated several Supermarine Spitfire PR.XI photo-reconnaissance aircraft and these became the first users of the new Type A-13 oxygen mask and Type A-14A regulators. National Museum of the U.S. Air Force Collection As World War II progressed, the USC Aero- medical Laboratory became increasingly busy, so the researchers turned many of the lesser tasks over to a young researcher named James Paget Henry (1914–1966). Henry was born to an American father and British mother and graduated from Sidney Sussex College in 1935. He earned a master’s degree from Cambridge University in 1938, an M.D. from USC in 1952, and a Ph.D. from McGill University, in Montreal, Canada, in 1955. Henry initially specialized in acceleration physiology using the USC human centrifuge from 1943 to 125S-1—GENESIS OF THE PARTIAL- unlimited access to funding and resources. 1947 and designed the first partial-pressurePRESSURE SUIT Former NACA chairman Vannevar Bush, suit. In 1947, Henry moved his pressure suit who reported directly to President Franklin work from USC to Wright Field as the ChiefIn February 1943, the Office of Scientific Delano Roosevelt, headed the organization. of the Acceleration Unit of the Aero MedicalResearch and Development (OSRD) awarded The research involved new and more accurate Laboratory. The following year he became aa small contract to the University of Southern bombs, reliable detonators, work on the prox- naturalized American citizen. During the earlyCalifornia (USC) Aeromedical Laboratory for imity fuze and radar, more effective medical 1950s, Henry was the director of the Air Forcethe further development of counter-pressure treatments, and (most secret of all) the “S-1 Physiology of Rocket Flight research projectand acceleration protective clothing.20 Execu- Section,” which later became the Manhattan and, in May 1952, supervised some of the firsttive Order 8807 created the OSRD on June Engineering District and developed the first successful animal rocket launches at Holloman28, 1941, to coordinate scientific research nuclear weapons. Although contracted and AFB, NM. He then became the director offor military purposes during World War II. It funded by OSRD, the Aero Medical Labora- the Project Mercury animal research effortsuperseded the work of the National Defense tory at Wright Field had technical cognizance for NASA. Henry left NASA in 1965 andResearch Committee and had virtually over the USC research.21 returned to USC as a professor of physiology.22 Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 4: Partial-Pressure Suits In late 1943, a group from USC arrived at the while breathing at high pressures. In response without overly hindering actions. The pres- Mayo Clinic to study the human centrifuge to this finding, the group embarked on the sure-breathing garment, on the other hand, in preparation for building a similar device development of a full-face, high-pressure could inflate relatively slowly and, generally, in Los Angeles. Included in the group were breathing mask, which would prove crucial once inflated it stayed inflated for a prolonged Dr. Douglas R. Drury, Dr. William G. for Henry’s pressure suit.25 period. Although the capstans could not Clark, and Jim Henry from the Departments respond quickly enough to provide meaning- of Physiology and Aviation Medicine.23 During a symposium at Mayo Clinic in early ful acceleration protection, they seemed excel- E.J. Baldes introduced each of the members, 1944, Dr. Harold Lamport of Yale University lent candidates to provide counter-pressure including Henry, to David Clark who was presented a paper on using external longi- over large areas of the arms and legs and, at Mayo observing G-suit tests. A few weeks tudinal bladders that could, when inflated, somewhat later, the shoulders and back. later, Henry asked Clark for assistance tighten a counter-pressure suit evenly and developing a new type of counter-pressure comfortably using interdigitating tapes and In April 1944, the Requirements Division at suit. Unfortunately, Clark had to decline since the so-called “capstan effect.” Helen Lester the Office of the Assistant Chief of Air Staff, in his small company was overwhelmed with and David C. Spooner at the Electric Blanket Washington, DC, asked the OSRD to investi- orders for G-suits and other war material. Division of General Electric had developed gate new types of pressure suits to replace the However, Clark offered to send materials, an the concept in consultation with Lamport failed Army effort to develop a full-pressure industrial sewing machine, thread, and the during 1943 in an attempt to revolutionize suit.27 Specifically, the requirements were for a services of his former experimental seamstress, G-suits. However, tests on the Wright Field, suit capable of operating at 60,000 feet for at126 Julia Greene, who had recently relocated with her husband to Burbank, CA. David Clark Mayo Clinic, and USC centrifuges showed the General Electric G-suit provided no least 30 minutes, while allowing a crewmem- ber to perform his duties with no permanent even agreed to pay Greene’s salary while she meaningful protection. However, the capstan medical consequences.28 The OSRD assigned assisted the USC team.24 idea struck a chord with Henry, who adopted the task to Henry at USC. it for use with his counter-pressure suit.26 By this time, USC had become the only Although the G-suit itself proved ineffective, Around the same time, the Army asked Dr. group in the United States studying pressure the capstan and pneumatic lever principle, Shannon Allen at the Aero Medical Labora- breathing. In November 1943, Douglas Drury along with the lace-adjustment feature, would tory to develop an emergency get-me-down assigned Jim Henry to lead a group to investi- shape most early partial-pressure suits. pressure suit for use with the Bell XS-1 (X-1) gate the issues associated with pressure breath- research airplane, and Shannon awarded USC ing. The researchers determined that as long The primary difference between a G-suit a small contract, which quickly found its way as the lungs were not allowed to overexpand, and pressure-breathing suit was the amount to Henry.29 almost any pressure could be used without of time available to inflate the capstans. A danger of aeroemphysema (a swelling condi- G-suit needs to react quickly to a changing These efforts were of particular interest to tion caused by the formation of gas in body acceleration environment, inflating and deflat- Lockheed, which was located just up the tissue). This relieved their fear of lung damage ing rapidly to provide protection for the pilot road from USC and, coincidently, employed Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 4: Partial-Pressure SuitsGreene’s husband. Engineers, led by Clarence the request of the National Research Council tapes covered the thighs and calves to provideL. “Kelly” Johnson, William P. Ralston, and to demonstrate the pressure vest and mask counter-pressure when needed. The capstansDon Palmer at the Lockheed Skunk Works he had developed for the RAF. Using the consisted of a molded, cold-resistant neoprenewere busy developing the second American jet Bazett vest and mask and a modified ver- tube inside a cloth sheath. When the capstanaircraft. In theory, the new P-80 Shooting Star sion of the unsuccessful G-suit developed by inflated, interdigitating tapes transmittedwould be capable of much greater operational General Electric and Harold Lamport, Henry the sheath tension to the cloth encircling thealtitudes than the piston-powered fighters of made a new type of altitude suit christened extremity. The advantages of the pneumaticthe era, and Lockheed engineers led by Lloyd a partial-pressure suit to differentiate it from lever (capstan) over the inflatable bladdersW. Jedeka wanted to know if the new pressure the full-pressure suit effort that the Army had used in early G-suits were that there were nosuit being developed by Henry could operate cancelled in late 1943.30 bladders in direct contact with the legs andat 55,000 feet. the pressure was applied more evenly over The garment began with a set of long-sleeve a larger skin area, minimizing discomfort.Henry Bazett, representing the Canadian coveralls. A large belly bladder, lifted directly Since the Army expected the partial-pressureAssociate Committee on Aviation Medical from a David Clark G-suit, provided pres- suit to be used for prolonged periods, atResearch visited USC in late April 1944 at sure to the torso. Capstans and interdigitating least compared with the few seconds or min- utes a G-suit was typically inflated, this was an important consideration. The suit used the standard Army A-13 oronasal pressure- breathing mask equipped with a Wildhack- Linde compensated exhalation valve and a 127 microphone. A set of Polaroid-GE electrically heated B-8 goggles completed the ensemble.31 At this point, the suit covered the torso and legs, but left the head, arms, hands, and feet Kelly Johnson was a driving force behind the first operational American jet fighter, the P-80. He would later drive the development of the first Mach 2 fighter (the F-104), the U-2 spy plane, and the Blackbird series of Mach 3 reconnaissance aircraft. All of these aircraft placed new demands on the pressure-suit industry. National Archives College Park Collection Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle | Dennis R. Jenkins
    • Chapter 4: Partial-Pressure Suits unprotected. Henry conducted the first test in tests by Harry Armstrong using rabbits had results. Although not tested above 60,000 feet, the USC altitude chamber on November 16, shown the possibility of serious gaseous swell- the suit demonstrated there was no particular 1944, with generally positive results. However, ing. When the ambient pressure surround- altitude limit at which it could be used, pro- based on early tests, several changes were made ing exposed parts of the body fell below the vided adequate counter-pressure was applied to the garment. For instance, the jock strap combined pressure exerted by the water vapor, across the tympanic membrane. Henry that held the pressure vest in place proved carbon dioxide, and oxygen tension in the tis- believed that, “some subjects might be able to somewhat uncomfortable, so Henry extended sues, the exposed region would swell, often employ the equipment in its present form for the vest bladder down over the perineum32 to grotesquely. The obvious conclusion was that short periods (5-10 minutes) in a vacuum.”37 provide protection against aeroemphysema. water in the hands had vaporized—boiled is To provide mobility, he added transverse break the more common term, although technically He