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


Published on

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

  1. 1. Dressingfor AltitudeU.S. Aviation Pressure Suits–Wiley Post to Space ShuttleDennis R. Jenkins
  2. 2. DRESSING FOR ALTITUDEU.S. Aviation Pressure Suits—Wiley Post to Space Shuttle
  3. 3. 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
  4. 4. 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
  5. 5. 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
  6. 6. 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
  7. 7. NaSa
  8. 8. 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
  9. 9. ivForeword
  10. 10. 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
  11. 11. 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
  12. 12. 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
  13. 13. Preface
  14. 14. 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
  15. 15. 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
  16. 16. 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
  17. 17. 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
  18. 18. 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
  19. 19. 1
  20. 20. 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
  21. 21. 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
  22. 22. 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
  23. 23. 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
  24. 24. 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
  25. 25. 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
  26. 26. 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
  27. 27. 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
  28. 28. 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
  29. 29. 2
  30. 30. 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