1. American Institute of Aeronautics and Astronautics
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A Small Artificial Gravity Generator for Experimental
Microgravity Flights
Stephen Hirst1
, Benjamin Corbin1
, Jeffrey Cunningham1
, Joe Coverston1
, and Jeremy Lawrence1
University of Central Florida, Orlando, Florida, 32817
The University of Central Florida chapter of the Students for the Exploration and
Development of Space (SEDS-UCF) have designed and built an autonomous experimental
artificial gravity centrifuge that meets all of the requirements for the experiment to be flown
as crew cargo onboard a ZERO-G Corporation microgravity research flight. The current
experimental configuration is designed to qualitatively view the effects of artificial gravity on
fluid boundary layer motion. However, the configuration can be changed for future flight
campaigns and multiple artificial gravity experiments.
Nomenclature
g = acceleration due to gravity
ac = centripetal acceleration
Fc = centripetal force
vt = tangential velocity
r = radius
m = mass
I. Introduction
N April 26th
, 2007, world-renowned physicist Stephen Hawking participated in a parabolic flight on the ZERO-
Gravity Corporation’s G-Force One.1
Afterwards, a new program was started for students to conduct research
in microgravity using small, automated boxes taken onboard the plane as crew equipment. The University of Central
Florida chapter of the Students for the Exploration and Development of Space (SEDS) has built one of the first five
experiments that will fly on the program’s maiden flight. The experiment contains a rotating platform with a large
prism that can hold mixtures of liquids, and the centripetal acceleration generated by the rotation is very close to the
force of gravity on Earth.
What follows is a brief Background of this microgravity program and the fundamental physics governing the
behavior of objects under rotational acceleration. The Experiment Design section details the many requirements that
the final design must meet in order to be flown legally under FAA regulations and describes the technical
specifications of the design. Finally, the Future Applications section discusses many of the alternative experiments
that can be done using the exact same equipment apparatus and a modified version of the spinning system.
II. Background
Microgravity flight research is the most inexpensive way to do reduced-gravity research for sustained periods of
time. The National Aeronautics and Space Administration (NASA) developed microgravity flight, and they have
used such research flights to train and assist manned and unmanned missions to space. With the national goal to first
colonize the moon and then take on the endeavor of becoming a multi-plant species, microgravity research is
essential to the advancement of these goals. This section is devoted to explaining what can be concluded about
microgravity experiments based off of prior knowledge.
A. Program Introduction.
This Project is a part of the pilot program for Stephen Hawking’s Microgravity Education and Research Center.
Since Stephen Hawking’s first microgravity experience in April of 2007, the Research Center has been in
1
SEDS-UCF Member, Mechanical, Materials, and Aerospace Engineering, 4000 Central Florida Blvd, Orlando, FL
32817, AIAA Student Member
O

2. American Institute of Aeronautics and Astronautics
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partnership with Space Florida and NASA. On
these experimental flights, 15 parabolas will be
flown, as is for research flights using G-Force
One
B. Process of Microgravity Flight.
A specially modified aircraft approved by
the FAA performs microgravity flights.2
Maneuvers are conducted in dedicated airspace
approximately 1000 square miles (100 miles
length by 10 miles width). Since controlling an
aircraft of that magnitude worthy of carrying
multiple research payloads is in itself difficult, specially trained pilots fly the aircraft in a series of parabolas to
create microgravity conditions in the research-payload area for approximately 30 seconds at a time.
The first stage (the preparation stage) of Microgravity Flight is when the aircraft pitches its nose to an angle of
45 degrees above the horizon. At this stage the experiment experiences increased amounts gravity due to an increase
in altitude. This takes the aircraft approximately 20 seconds to complete its climb from approx. 24,000 feet to
32,000 feet.
Stage 2 (the microgravity stage) consists of the pilots “pushing over” the aircraft at the “top” of the parabola to
create the “weightlessness/microgravity effect” which is between 20 and 45 seconds from when the parabola
officially begins. It is during Stage 2 that the experiments onboard will feel the effects of microgravity. It is crucial
for the accuracy of the experiment and for the safely of the crew that the pilots slowly conduct the plane to a level
altitude so that maximum amount of “Microgravity Time” is allowed for experiment to get the best results.
Stage 3 (the recovery stage) consists of the crew “recovering” the airplane to a stable flying altitude on which it
started (approximately 24,000 feet). This is so the aircraft can repeat the process until all required or desired
parabolas are achieved. Figure 1 shows these stages
C. The Physics of Microgravity
Microgravity is the condition in which an object is in synchronization with the acceleration of an object of a
greater mass. Also called “Free Fall”, Microgravity is the state of an object “constantly” falling. In space,
Microgravity is created either by being away from a bigger mass or by being in orbit (a state of constant free fall
around a reference object). Achieving microgravity on earth using aviation is simple. An airplane must change its
acceleration towards the earth at a rate equal to that of the acceleration of gravity. This is done on research aircraft
that fly parabolas to first increase altitude then rapidly change acceleration (equaling that of gravity) downward. The
time of absolute microgravity is restricted to about 30 seconds due to airspace restrictions; however, the amount of
parabolas made is depended upon the fuel capacity of the aircraft.
There is a common misconception about the term “zero gravity.” Gravitation is the natural phenomenon by
which all objects with mass attract each other. Any object that has mass has attractive force to another body of mass.
This reveals that gravitation is a force and therefore must have mass and acceleration. Therefore, absolutely zero
gravity is impossible when another body of mass is present anywhere in the universe. The term “microgravity”
accounts for the ever-present miniscule amount of gravity (Approximately 1x10^-6 g) on a “weightless” system in
our universe.
D. The Physics of Artificial Gravity
Currently the most feasible way to achieve artificial gravity in a microgravity environment is use centrifugal
force. According to Newton’s mechanics, Eq. 1 can describe centrifugal force.
Fc m ac m
v
2
r (1)
With the current configuration of our experiment, the fluid containment area is approximately 9 inches in
diameter; therefore, the radius is 4.5m inches. There are several side effects to using rotational artificial gravity,
including having a gravity gradient. A gravity gradient is in effect when there is a lesser gravitational force as you
approach the axis of rotation. We have designed the motor system to achieve and acceleration at its endpoints equal
Figure 1. Approximate flight path of a parabolic flight.2

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to that of gravity (approximately 9.8 m/s2
). Therefore, the system has a gravitational gradient with approximately
1x10-6
g at the axis of rotation and 1g at the endpoints. This would require the tangential velocity to be about 1.058
meters per second.
III. Experiment Design
A. Requirements
The ZERO-G Corporation battled the FAA for 10 years to gain permission to fly civilians on parabolic flight
campaigns. However, in order to stay in business, ZERO-G must still follow many of the rules set forth by the FAA
for airline companies. One FAA rule is that all airliners must have a luggage security manual in order for any
passengers to legally carry anything aboard the plane. Since ZERO-G does not have this manual, passengers cannot
bring on any equipment. Therefore, all flight experiments under this campaign must be classified as crew equipment
and pass the same standards as commercial airliner crew equipment.
In order to be classified as crew equipment and fit on board the pre-designated slots on board G-Force One, all
experiments must follow many strict requirements. In order to fit in the crew cargo closet, the experiment must be
contained in a 12x12x16 inch non-flammable box (There are spaces for 12x12x9 inch experiments underneath some
of the few passenger seats on board the plane). In addition to the given dimensions, the experiment had to have both
an inner and outer containment mechanism for the liquid experiment inside to safeguard against the possibility of
leakage. The outer casing of the experiment box had to be constructed of non-flammable and durable materials. The
inner experiment also had to be constructed so that it would continue to operate when tilted at all angles and shaken
on the ground. If the experiment contains Velcro, even that must be fireproof.
Because the experiment will be stored in an unreachable location during the flight, the entire experimental
operation must be automated once the experiment is activated by a ZERO-G crewmember. Passengers and
researchers will not be able to turn on the experiment, so instructions for turning on the experiment must be clearly
places on the front of the apparatus.
B. Design Specifications
The box was constructed from 12 angle aluminum 1/16” x 3/4” x 48” from Crown Bolt, Inc., and was bolted
together using 3 bolts per corner with machine round head slotted bolt and nut #6-32 x 3/8”, zinc for a total of 8
corners with 24 bolts. Holes were drilled into the 16” angle aluminum so that the Valley Roll AL EC 14” x 10’ sheet
aluminum could be bolted using machine round head slotted bolts and nuts #6-32 x 3/8”. The top and bottom
aluminum plates were made out of 5005 aluminum plating and were bolted to the angled aluminum in the same
manner as the sheet aluminum. The door was constructed from galvanized sheet metal and 2 flat aluminum pieces,
1/8” x 1” x 36” from Crown Bolt, Inc. were added to the
aluminum angle frame on the outside to connect the door to the
frame. Silicone sealant was placed in a ridge surrounding the door
on the aluminum angle and aluminum flat pieces in order for the
door to form an airtight seal. Silicone sealant was also used on the
inside of the box to seal the sheet aluminum and aluminum plate
to fulfill the FAA requirement of double containment. For the
inner rotating mechanism, 2 iron pipe flanges were welded
together and then bolted to the bottom aluminum plating of the
box. A Solidworks design of the experiment is shown in Fig. 2
and a recent photo of the final design is shown in Fig. 3.
Although experiments similar to this one have been performed
in previous microgravity campaigns under NASA’s Microgravity
University and other ZERO-G research campaigns, this
experiment is the first one to be fully automated. A Sony DSC-
S700 camera carrying a 2-gigabyte memory card and fresh
batteries is mounted to the upper platform. Four LED flashlights
mounted on the support rods provide enough illumination to view
the movement of liquids within the prism. Once the experiment is
completed, video data can be analyzed using a variety of video
software.
Figure 2. Solidworks model of experiment

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IV. Future Applications
A. Alternate Experiments in the Same Design Configurations
The first flight will only contain water and oil to demonstrate
the durability of the experiment and the ability to handle more
dangerous liquids that may not be allowed by the FAA. The FAA
is already worried about the flammability of oil and is only
allowing the experiment because it contains water. In the future,
more scientifically relevant fluids will be studied.
In addition to the separation of fluids of varying densities, the
apparatus can also accomplish the flash distillation of miscible
fluids by separating the phases created during partial vaporization.
Such a “phase separator” has a variety of alternative research
applications, such as conducting experiments to improve the
liquefaction of cryogenic fuels. Similar experiments can also
improve the thermodynamic efficiency of nuclear-electric
propulsion drives, of which a centrifugal phase separator is a
critical component.3
The distilling process involved also aids in
the decontamination of water, which proves invaluable to studies
of in-situ resource utilization systems on manned deep space
missions. Further experiments can also observe the effect of the
absence of gravity-induced buoyancy effects on alloy melting,
diffusion, crystal growth, and more.
B. Experiments with a Modified Apparatus
Although the current experimental configuration only supports liquid testing, applications of a small centrifuge
that can generate 1-g of acceleration at the endpoints are useful for studies in biology and animal behavior among
others. By surrounding the circular platforms with a flexible wall panel and moving the flashlights to the other sides
of the rods, a cage for small animals can be made to study how animals react to changes in the direction of the
acceleration vector. Whether or not these types of experiments will be allowed is still up for debate, however.
Because this experiment is automated, it can be placed on any microgravity flight that has room for it, whether it
flies with NASA or with ZERO-G.
V. Conclusion
The maiden voyage of this experiment will be conducted two days after this paper is submitted for publication.
SEDS hopes that this experiment will be used not only for this flight and this experiment but also for future studies
in fluid mechanics under artificial gravity. After the first flight of this pilot program, flights will be conducted more
often, resulting in more experiments and more contributions to microgravity studies.
Acknowledgments
The authors would like to acknowledge the help of Al Ducharme, PhD. as a project advisor for the experiment.
They would like to recognize the assistance of Ryan Maticka, Jason Dunn, Roberto Cloretti, and Erich Dondyk on
construction of the experiment. They would also like to thank Dr. Larry Chew, Matthew Reyes, the National
Aeronautics and Space Administration, Zero Gravity Corporation, and the University of Central Florida for all of
their efforts in making sure the project was successfully completed.
References
1
Boyle, A., “Hawking goes zero-G: ‘Space, here I come’,” MSNBC. 26 April 2007. URL: http://www.msnbc.msn.com/id/
18334489/ [cited 20 February 2008].
2
Zero Gravity Corporation, "How Parabolic Flight Works." Zero Gravity Corporation. URL: http://www.gozerog.com/how-
it-works.htm [cited 16 Feb 2008].
3
Committee on Microgravity Research, Space Studies Board, National Research Council, Microgravity Research in Support
of Technologies for the Human Exploration and Development of Space and Planetary Bodies, National Academics Press, 2000.
Figure 3. Experiment ready for flight.