Aeroship: A Hybrid Flight Platform for Planetary Flight,
Near-Space Flight and Personal Flight
Tianshu Liu, W. W. Liou, & M. Schulte
Department of Mechanical and Aerospace Engineering
Western Michigan University, Kalamazoo, MI 49008
Motivations
• Originally, the concept of aeroship (hybrid flight
vehicle) is proposed for designing a low-speed flight
vehicle with very short-takeoff/landing (STOL)
capability on Mars.
• Then it is found that aeroship is particularly suitable
to personal flight and high-altitude (near-space) flight
in the Earth atmosphere.
Conventional Flight Platforms
Aerostatic Force vs. Aerodynamic Force
The non-dimensional parameter: a ratio between the
aerodynamic force and total weight
W/)LW(W/W shipA
1A 0A
Grey or Fuzzy
Domain
10 A
Opportunities in a “Fuzzy” Parametric Domain
Optimum Equilibrium between
Aerostatic Force & Aerodynamic Force
for Challenging Flight
10 A
• Short takeoff/landing on a small open area (30-50 m)
Requirements for Personal Flight Vehicle:
• Good maneuver and easy control (level turn in 5 m)
• Reasonable cruising speed (50 km/h)
• Always soft landing in emergency situations
Generic Aeroship Configurations
Personal Aeroship
Airship module +
Wing/propulsion module
Generic Aeroship Configurations
High-Altitude Unmanned Aeroship
Generic Aeroship Configurations
Flapping-Wing Aeroship
Aeroship Force Equilibrium
Level Flight Climb
Gliding Level Turn
Relevant Physical Quantities and Parameters
)2/SU(CVgCL wing
2
LshipL wingship
The total lift of aeroship:
The total drag of aeroship:
)2/SU(C)2/SU(CD wing
2
Dship
2
D wingship
wingship DSDwing
2
D CRC)2/SU/(DC
The total drag coefficient:
wingshipS S/SR
The characteristic area and force ratios:
)]C/C(R1/[1wingship LLFA
A relation between the characteristic parameters:
)2/SU/(gVR wing
2
shipF
Aeroship Flight Performance
Thrust and Power for Steady Flight
2
wing
2
wing
0,DSDwing
2
RS
W
U
SK2)CRC)(2/SU(DT
wingship
The thrust required for level flight:
2/1
wing0,D
)T(S
W
C
K2U
minR
The velocity at the min thrust required for level flight:
3
Lwing
2
D
3
DL
RRCS
CW2
C/C
UWUTP
The power required for level flight:
The velocity at the min power required for level flight: 2/1
LF
2
L
2
F0,Dwing)C/C(
shipship
maxD2/3
L CRCR4K/C3
1
S
W2U
Aeroship Flight Performance
Maximum Lift-to-Drag Ratio
KC/241.1)D/L( 0,D2max
Optimum condition:
K/C761.0)CR( 0,DopLF ship
The velocity at max L/D: 2/1
wing0,D
)D/L(S
W
C
K2891.0U
max
Aeroship Flight Performance
Comparison with Aircraft on L/D
0,wingship DDSaircraftmax,
aeroship,2max
C/CR1
482.2
)D/L(
)D/L(
The max L/D:
0,wingship DDS
aircraftL
aeroshipLC/CR1257.1
)C(
)C(
The lift coefficient at the max L/D:
0,wingship DDSaircraftmax,)D/L(
aeroshipmax,)D/L(
C/CR1
891.0
U
U
The velocity at max L/D:
Aeroship Flight Performance
Climb
wing
2
21
wing
0,D
2
wing S
W
U
cosK2
S
WC
2
U
S
TUsinUC/R
The climb rate:
wing
2
21
wing
0,D
2
wing
pr
S
W
U
cosK2
S
WC
2
U
US
Psin
The climb angle:
2
wingwingpr S
W
)S/P(
K4U
max
The velocity at the max climb angle:
Aeroship Flight Performance
Gliding
The sink velocity:
The stall velocity:
wing
2
D
3
L
VS
W
C/C
2U
wing
W
W
C
C
U
U
wingD
D
aircraft,V
aeroship,V
Stall
wingmaxLFL
stallS
W
])C(RC[
2U
wingship
2/1
maxLLFaircraft,stall
aeroship,stall
)C/(CR1
1
U
U
wingship
Aeroship Flight Performance
Level Turn
2
0,D
wing
min
)W/T/(KC41)W/T(g
)S/W(K4R
The min level turn radius:
)W/T(
)S/W(K4U
wing
Rmin
The velocity at the min level turn:
Free Falling Velocity
2shipDship
VCS
W2U
Lake of Michigan
Conceptual Design of Personal Aeroship
Aeroship Component Mass
Wing 24 kg
Engine 40 kg
Propeller 3 kg
Instrument & wires 4 kg
Tails 9 kg
Fuselage 60 kg
Airship hull 30 kg
Pilot 80 kg
Total mass 250 kg
Mass Estimate
Intrinsic design parameters
Total weight (Newtons) 2450
Airship lift (Newtons) 1479.8
Wing area (m2) 12
Wing aspect ratio 5.3
Wing span efficiency 0.8
Airship characteristic area (m2) 14.25
Airship vertically projected area (m2) 40
Airship volume (m3) 144
Wing parasite drag coefficient 0.02
Airship drag coefficient 0.04
Wing lift coefficient 0.6
Maximum wing lift coefficient 1.4
Airship drag coefficient in free fall 1.2
Atmosphere density (kg/m3) 1.225
Helium gas density (kg/m3) 0.1785
Design Parameters
Climb Performance Compared with Aircraft
Max R/C
Climb Angle at Max R/C
Level Turn Performance Compared with Aircraft
Min Level Turn Radius
Speed at Min Level Turn
Takeoff Ground Roll Compared with Aircraft
Intrinsic Performance Parameters Aeroship Aircraft
U at the min thrust (m/s) 11.79 25.41
max L/D 17.43 12.90
U at the max L/D (m/s) 16.70 25.41
CL at the max L/D 1.19 0.51
U at the min power required (m/s) 14.64 19.31
CL at the min power required 1.55 0.894
CD at the min power required 0.164 0.08
The min power required (watts) 3807.08 4233.45
U at the max R/C (m/s) 14.64 19.31
glide angle (deg) 8.95 4.48
Uv, sink velocity, in gliding (m/s) 2.33 1.85
U stall (m/s) 8.52 15.43
Uv, sink velocity, in free fall (m/s) 5.74 -
Personal Aeroship Performance Parameters
High Altitude or Near-Space Aeroship
• Short takeoff/landing
• High lift-to-drag ratio
• Good maneuverability
• Low engine power required (solar powered)
Altitude:
> 30 km (100,000 ft)
Conceptual Design of High-Altitude Aeroship
Airship Component Mass
Airship hull 48 kg
H2 gas 5.5 kg
Wing/propulsion 36 kg
Payload 30.5 kg
Total mass 120 kg
Intrinsic Design Parameters
Total weight (Newtons) 1176
Airship lift (Newtons) 705.6
Wing area (m2) 30
Wing aspect ratio 7.5
Wing span efficiency 0.8
Airship characteristic area (m2) 136.2
Airship vertically projected area (m2) 514.5
Airship volume (m3) 4247
Wing parasite drag coefficient 0.02
Airship drag coefficient 0.04
Wing lift coefficient 0.6
Maximum wing lift coefficient 1.4
Airship drag coefficient in free fall 1.2
Atmosphere density (kg/m3) 0.0183
Gas density (kg/m3) 0.00128
Altitude for cruise (m) 30000
Mass Estimate Design Parameters
Parametric Variations with Altitude (without releasing the light gas)
Normalized Pressure Difference
Across the Hull Skin Airship Volume Lift
Parametric Variations with Altitude (with suitable initial gas mass and releasing the gas later)
Normalized Effective Gas Volume
Airship Lift
Climb Trajectory of High-Altitude Aeroship
Altitude with Horizontal Distance
Altitude with Time
High-Altitude Aeroship Performance Parameters
at Altitude of 30 km
Intrinsic Performance Parameters
U at the min thrust (m/s) 29.61
max L/D 12
U at the max L/D (m/s) 41.72
CL at the max L/D 2.45
U at the min power required (m/s) 36.48
CL at the min power required 3.21
CD at the min power required 0.44
The min power required (watts) 5880.14
U at the max R/C (m/s) 36.48
glide angle (deg) 20.2
Uv, sink velocity, in gliding (m/s) 19.63
U stall (m/s) 15.93
Uv, sink velocity, in free fall (m/s) 9.11
Model Aeroship and Flight Testing Design Parameters
Total Weight, W, (N) 19
Gas Envelope
Volume (m3) 1.08
Gross Buoyancy Lift (N) 13.3 (70% W)
Weight of Envelope (kg) 0.48
Front-Projected Area (m2) 0.98
Vertical-Projected Area (m2) 1.5
Max. Length (m) 2.3
Max. Diameter (m) 1.1
Horizontal Fin Area (m2) 0.25
Vertical Fin Area (m2) 0.126
Wing Parameters
Wing Section NACA4312
Span (m) 1.52
Chord (m) 0.203
Wing Area (m2) 0.309
Vertical Tail Parameters
Cross-Section flat plate
Area (m2) 0.053
Rudder Area (m2) 0.053
Vertical Tail Volume 0.102
Horizontal Tail Parameters
Cross-Section flat plate
Area (m2) 0.155
Elevator Area (m2) 0.155
Horizontal Tail volume 2.09
Videogrammetry in Flight Testing
Two-camera videogrammtric
system
Intensity-inversed image
Takeoff Performance
Rate of Climb Speed in Takeoff
Landing Performance
Rate of Climb Speed in Landing
Short Climb Performance
Rate of Climb Speed in Climb
Glide Performance
Rate of Climb Speed in Glide
Level Turn Performance
Left Turn Right Turn
Parameter Estimated Measured in Flight
Takeoff Ground Roll 5 m 3 m
Takeoff Speed 4.6 m/s 4.2 m/s
Approach Angle in Landing 15 deg 16.7 deg
Touch-Down Speed in Landing 4.6 m/s 3.3 m/s
Max. R/C 3.1 m/s 2.5 m/s
Angle at Max. R/C 30 deg 32.3 deg
Velocity at Max. R/C 6.1 m/s 4.5 m/s
Descent Rate in Glide 2.3 m/s 1.4 m/s
Glide Angle 15.4 deg 19.4 deg
Stall Speed 4.2 m/s 4.2 m/s
Min. Level Turn Radius 5.5 m 3.6 m (left), 5.3 m
(right)
Comparison between Predicted and Measured
Performance Parameters
The 24-foot Airship Model in Flight
Conclusions
• Short takeoff/landing (STOL)
• High lift-to-drag ratio
• Good climb and turn performance
• Low engine power required
• Emergency safety
Aeroship is an optimized integration of airship module
and wing/propulsion module