AIAA ADS Conference 2011 in Dublin
1
Deployment and Flight Test
of Inflatable Membrane Aeroshell
using Large Scientific Balloon
Kazuhiko Yamada, Takashi Abe (JAXA/ISAS)
Kojiro Suzuki, Naohiko Honma, Yasunori Nagata,
Masashi Koyama (The University of Tokyo)
Daisuke Abe, Yusuke Kimura,
A. Koichi Hayashi (Aoyama Gakuin University)
Hitoshi Makino (Tokai University)
Daisuke Akita (Tokyo Institute of Technology)
2011/05/25
AIAA ADS Conference 2011 in Dublin
2
CONTENTS
 Background
Membrane aeroshell for atmospheric-entry capsule (MAAC)
Advantage and key technology.
 Inflatable aeroshell flight test using balloon (Mini MAAC)
Objectives.
Experimental vehicle.
Flight operation.
Results.
 Conclusions
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
3
Background
“HAYABUSA” capsule returned to the earth with success.
From now on, even more sample return missions and planetary
entry missions will be proposed.
Withstand
Aerodynamic heating
We weed innovation of atmospheric-entry system for frequent
space transportation between space and planet surface.
One of the candidates is flexible aeroshell system
Large and light aeroshell is deployed
in the space before reentry
Avoid
Aerodynamic heating
Flexible aeroshell can be
packed in launching and
operating in space.
Vehicle re-enters into atmosphere with low
aerodynamic heating and make soft landing
without a parachute
Flare-type membrane aeroshell supported by inflatable torus.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
4
Advantage and key technology
<Advantages of flexible aeroshell>
 Significant reduction of aerodynamic heating during reentry.
Vehicle with large and light aeroshell can decelerate at high altitude
where the atmospheric density is very low.
 Soft landing without additional parachute system or retro jet.
Large and light aeroshell also works to reduce terminal velocity
same as conventional parachute before landing.
<Key technologies of flexible aeroshell>
1) To understand aerodynamic characteristics
 in whole range of Mach number
Inflatable torus
2) To develop and evaluate flexible material
 especially thermal durability
3) To develop a large but low-mass flexible aeroshell
 utilizing inflatable structure
Thin membrane
Capsule
(payload)
Demonstration and investigate on inflatable aeroshell using a balloon
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
5
MINiature Inflatable MAAC experiment (MINI-MAAC)
<Objectives>
To demonstrate deployment and free flight of flare-type aeroshell supported by
inflatable torus which is one of the next generation reentry system.
 To demonstrate the aeroshell deployment in vacuum condition in the air
with remote control.
 To acquire the knowledge of the structural strength of inflatable torus
against aerodynamic force during free flight condition.
 To obtain the aerodynamic characteristics of low-ballistic-coefficient vehicle
in subsonic regime in free flight condition.
Free drop
Launch
All flight data is transmitted
to ground station.
Deployment and Separation
at ALT=25km
Ascend
Aeroshell is packed
Vehicle separation from gondola
after aeroshell deployment .
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
We does not request recover of
experimental vehicle
2011/05/25
AIAA ADS Conference 2011 in Dublin
6
Overview of Experimental System
Flight configuration
<Gas injection device>
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
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Experimental flight vehicle
Capsule
Packed aeroshell
Deployed aeroshell
Total mass : 3.375kg
 All of device including sensor, telemetry, transmitter and battery is in capsule.
Measurement item: Image of aeroshell, Ambient pressure, Inflatable pressure,
Position by GPS, Accelerator, Angle velocity and so on
 Flare part was made of Nylon cloth.
Inflatable torus was made of Nylon cloth coated by Urethane rubber.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
8
Deployed configuration of aeroshell
Before flight, deployment rehearsal was carried out in ambient pressure at sea
level (=100kPa) with remote command and gas injection devices.
Deployment
Gas injection
Remote
command
(Inflatable pressure = 120kPaA, 20kPaG)
60kPa X 2
The aeroshell was deformed into saddle shape due to the out-of-plane buckling of
inflatable torus.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
9
Flight operation
This experiment was carried out at TARF in 25th August, 2009.
Just before launch
Successful launch and ascend.
User’s room
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
10
Results of MINI-MAAC
All of test sequence was carried out as planned and the flight test was
very successful and fruitful.
We acquired a lot of information and technology for flare-type inflatable
aeroshell from MINI-MAAC experiment as following.
 Deployment technique in vacuum condition with remote control.
 Vehicle trajectory in horizontal direction compared with wind profile.
 Drag coefficient in low speed regime during free flight .
 Attitude of experimental vehicle during free flight.
 Data of structural strength of inflatable torus against aerodynamic
force.
These data in free flight condition are acquired just only flight test.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
11
Deployment demonstration
The inflatable aeroshell was deployed by injecting gas at altitude 25km.
Inflatable pressure history
Gas injection finish
Deployment was completed in 0.3 second after gas injection.
Inflatable pressure reached the design value in 6 seconds after gas injection.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
12
Separation from gondola
Experimental vehicle was separated from gondola after deployment.
From gondola
3-axis Acceleration history
Decelerate by aerodynamic force
From capsule
Capsule inclined
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
13
Horizontal Trajectory
Horizontal trajectory was determined by GPS data
<Horizontal flight trajectory >
<Comparison with wind profile>
Horizontal velocity vector almost coincided with the wind velocity and direction.
 Experimental vehicle dropped with zero horizontal airspeed
 aerodynamic characteristics can be understood only by considering vertical motion.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
14
Drag coefficient
Drag coefficient during free flight was estimated from altitude history.
<Time history of altitude>
Aeroshell was collapsed in 24 min after
separation at altitude 4.0km as planned
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
<Comparison with simulation>
Drag coefficient of vehicle is constant in 1.0
though the ambient pressure changed
significantly during free flight
2011/05/25
AIAA ADS Conference 2011 in Dublin
15
Motion and attitude of Capsule
Motion and attitude of capsule was measured by 3 axis acceleration sensors
and angle velocity sensors around the body axis.
<Roll angle velocity history>
Roll angle velocity
<Capsule inclination history>
Inclination
Gravity force
Capsule rotated around the body axis in 0.6Hz in maximum
Capsule inclined against the gravity force in 15 degrees in maximum
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
16
Relation between aeroshell and capsule
Aeroshell image captured through
the fisheye lens
Comparison between capsule
inclination and aeroshell inclination
The angle between capsule body axis and center line of the aeroshell coincide with
inclination of capsule against the gravity force.
 The aeroshell center line was almost same as the gravity force direction ,although
the capsule inclined against the gravity force.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
17
Attitude and motion of vehicle during flight
<Schematic of attitude and motion>
Capsule inclined against gravity force direction.
Capsule rotated around the body axis.
Aeroshell center line coincide with gravity force
direction
The capsule inclination and the angle velocity
decreased gradually as the experimental vehicle
descended.
non-axisymmetric deformation into saddle
shape due to out-of-plane buckling cause
the unexpected motion and attitude.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
18
Structural Strength of inflatable torus
The inner pressure in inflatable torus is purposely set to about 60kPaA．
 The aeroshell was collapsed during flight due to ambient pressure increase
<Aeroshell Image>
<Time history of inflatable pressure>
Steady
300sec
900sec
Sudden collapse
1200sec
Separation
Collapse
5.2kPa
1380sec
1440sec
Aeroshell was collapsed when the differential pressure is 5.2kPa in free flight.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
19
Comparison with simple analysis
The most simple prediction for structural strength is derived,
considering the balance between compressive force by external force and
Tensile force by inner pressure.
In this assumption,
aeroshell was collapsed
in only local crippling mode
FD  2
1 cos in
 r2 p
C AR sin  out
r = 0.032m
Θin = 40 deg
Θout = 75 deg
CAR = 0.97
FD = 33N
Threshold pressure = 2.1 kPa < 5.2 kPa : Flight data
The aeroshell did not collapse in the crippling mode in the flight test,
due to the considerable out-of-plane buckling deformation of the inflatable torus.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
20
Conclusions of MINI-MAAC
Our group carried out “Deployment and flight test of inflatable aeroshell”
using large scientific balloon in series of development of “membrane
aeroshell for new atmospheric-entry system”
This balloon test was very successful and fruitful.
Our group achieved the following results in this test.
1) The aeroshell deployment by injecting gas to the inflatable torus was
demonstrated through the remote command in the high altitude.
2) The flight trajectory, the vehicle attitude and motion and the aerodynamic
coefficient in the free flight was obtained by the onboard sensors and the
telemetry system.
3) The structural strength of the flare-type aeroshell sustained by the
inflatable torus was measured in free flight condition to compare the flight
data with the prediction of the preliminary analysis.
These data will be very useful for the vehicle design in next phase of
development.
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25
AIAA ADS Conference 2011 in Dublin
21
Fin
MAAC / Membrane Aeroshell for Atmospheric-entry Capsule
2011/05/25