solar airplane design - phd slides - ethz - a. noth (30.09.2008)
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7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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Autonomous Systems LabETH Zentrum
Tannenstrasse 3, CLA8092 Zürich, Switzerland
AUTONOMOUS SYSTEMS LABAUTONOMOUS SYSTEMS LAB
Design of Solar Powered Airplanes for
Continuous Flight
André NothDoctoral Exam – September 30, 2008
1/30
http://www.sky-sailor.ethz.ch/E-mail: [email protected]
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Outline
1/30
• Introduction
• Design Methodology• Sky-Sailor Design
• Sky-Sailor Prototype
• Scaling• Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Motivations & Objective
2/30
• Project started with an ESA feasibility study
Introduction
y Motivationsy History of Solar Flight
y State of the Arty Contributions
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
Mars exploration
Satellites + extensive coverage, good resolution- place of interest not freely selectable
Rovers + excellent resolution, ground interaction- reduced range, limited by terrain
? Gap for systems with + high-resolution imagery+ extensive & selectable coverage
Î Study the feasibility of solar powered flight on Mars
Î Develop and realize a fully functional prototype on Earthand demonstrate continuous flight
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
History of Solar Flight
3/30
70’s 80’s 90’s 2000’s
Introduction
y Motivationsy History of Solar Flight
y State of the Arty Contributions
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
• Started in 1974
• 90 solar powered airplanes listed from 1974 to 2008
Sunrise (1974)1st solar powered flight
Solar Riser (1979)manned, battery solar
charged for short flights
Gossamer Penguin (1980)1st manned solarpowered flight
Sunseeker (1990)manned, crossedthe USA in 21 flight
Solar Challenger (1981)manned, channel
crossing
Helios (1999)umanned, flew at
> 29’000 m
Zephyr (2005)umanned, flew 83h
Solong (2005)1st continuous flight,used thermals
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
State of the art
4/30
Many solar airplanes in HistoryÎ … but no clear design methodologies explained
Î anyway useful practical papers on case studies
[BOUCHER79, MACCREADY83, COLELLA94]
Many design methodologies…
Î … but rarely validated with a prototype [REHMET97, WEIDER06]
Î very often nice design methods[IRVING74, YOUNGBLOOD82, BAILEY92]
but based on weak models for:
• Weight prediction
• Efficiencies
Î ends with irrealistic designs
[RIZZO08, ROMEO04]
Introduction
y Motivationsy History of Solar Flight
y State of the Arty Contributions
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
design
method
math.models
[ULM96,BRUSS91]
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Contributions
5/30
• Design methodology
– Simplicity
– Large design space
– Concrete and experienced based
– Flexible and versatile
• Theory validation with a prototype– Achieve > 24h flight
– Autonomous control
• Draw up a state of the art on solar aviation
– History
– Publications
Introduction
y Motivationsy History of Solar Flight
y State of the Arty Contributions
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Design Methodology
6/30
Introduction
Design Methodology
y Required Energyy Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Methodology
7/30
• Sizing the airplane : hen & egg problem
?
Airplane Parts• Solar cells
• Battery• Airframe• Payload•…
Î Total weightAerodynamics & flight conditions
Î Level Flight Power
Weight balance
Energy balance
• This loop can be solved:
Iteratively (trying existing components, refining the design)
Analytically (using mathematic models of the components)
ÎAllows to establish some general design principles
AABB
Introduction
Design Methodology
y Required Energyy Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Required Energy
• Equilibrium at steady level flight
8/30
2
2
2
2
L
D
L mg C Sv
D T C Sv
ρ
ρ
= =
= =
• Power required
3
3/ 2
( ) 2 Dlevel
L
C mgP D v
C S ρ = =
• Daily energy required
night
elec tot elec tot day
chrg dchrg
T E P T
η η
⎛ ⎞= +⎜ ⎟⎜ ⎟
⎝ ⎠
1
1( )
electot level
ctrl mot grb plr
av pld
bec
P P
P P
η η η η
η
=
+ +
Introduction
Design Methodology
y Required Energyy Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion levelP
electot P
grbη
ctrlη
mot η
plr η
becη
av pld P P+
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Required Energy
8/30
Introduction
Design Methodology
y Required Energyy Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Solar Energy
• Daily average solar irradiance– Irradiance ~ cosine
– I max T day = f(date, location, weather)
9/30
• Daily energy obtained
• Daily energy required = Daily energy obtained
ÎWe compute
/ 2
max day
day density wthr
I T E η
π =
elec tot day density sc sc cbr mppt
E E A η η η =
Introduction
Design Methodology
y Required Energyy Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
sc cbr η η
mppt η
day density E sc A electot E
sc A
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Required Energy
9/30
Introduction
Design Methodology
y Required Energyy Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Weight Prediction Models
• Fixed Masses
10/30
• Airplane Structure
– In the literature
• [BRANDT95, GUGLIERI96,…] consider
Î valid locally
• [HALL68] calculated all airframe elements separately
Î complex, only valid for 1000-3000 lbs airplanes
• [STENDER69] proposedÎ very widely adopted
Î adapted by [RIZZO04] to UAV
af W k S = ⋅
• Payload
• Avionic System (Autopilot)
pld m
avm
Introduction
Design Methodology
y Required Energy
y Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
0.311 0.778 0.467
8.763af W n S AR=
0.656 0.65115.19af
W S AR=
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Weight Prediction Models
• Verification of these models– Database of 415 sailplane
– Structure Weight vs Area
ÎModels don’t fit well
11/30
Introduction
Design Methodology
y Required Energy
y Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion pessimistic
optimistic
3.10 0.250.44af
W b AR−= ⋅
• New model proposed
– Same equation, new coef.
– Least square method fit
– Data set divided in two
– 5 iterations = 5 qualities– Best 5% model:
Keywords: Wing weight to area , wing area as a functionof structural weight, great flight diagram, Tennekes, wingmass to area, mass to surface, area to mass, surface tomass.
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Weight Prediction Models
OverviewBiologists already studied flyingin nature to extract tendencies
[TENNEKES92] presented the« Great Flight Diagram »
Clear cubic tendancy
Introduction
Design Methodology
y Required Energy
y Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
Our model is // to Tennekes curve
[STENDER69,RIZZO04] seem
incoherent
Keywords: Wing weight to area , wing area as a function
of structural weight, great flight diagram, Tennekes, wingmass to area, mass to surface, area to mass, surface tomass.
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Required Energy
12/30
Introduction
Design Methodology
y Required Energy
y Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Weight Prediction Models
• Solar Cells– Surface = f(cells properties, required energy)
– Weight proportionnal to the surface
• Maximum Power Point Tracker
– Study of high efficiency MPPT
ÎWeight linear with Pmax
13/30
• Batterie
– Weight proportionnal to capacity
( )sc sc sc encm A k k = +
mI
mppt mppt sol max
mppt ax sc cbr mppt sc
m k P
k Aη η η
=
=
night
bat elec tot
dchrg bat
T m P
k η
=
Introduction
Design Methodology
y Required Energy
y Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Required Energy
13/30
Introduction
Design Methodology
y Required Energy
y Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Weight Prediction Models
• Propulsion group– Existing models but none is proven on a large range
– Very large databases created
2264 motors
170 electronics controllers
997 gearboxes
673 propellers
14/30
Introduction
Design Methodology
y Required Energy
y Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
Interpolated Models
Keywords: Mass to power ratio of motors / Power to mass ratio of electrical motors, piezoelectric motors, Motor mass to power ratio / Motor power tomass ratio of electromagnetic motors, brushed and brushless motors energy density, power density, density of energy, density of power.
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Summary and Resolution
15/30
Mission parameters
Others: Technological parameters
Airplane’s shape variables
Î Search b and AR for which the loop has a solution
Introduction
Design Methodology
y Required Energy
y Solar Energyy Weight Modelsy Resolution
Sky-Sailor Design
Sky-Sailor Prototype
Scaling
Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Sky-Sailor Design
16/30
Introduction
Design Methodology
Sky-Sailor Design
y Math. Applicationy Real-Time Simulation
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Methodology application
• Mission parameters– Solar flight possible 3 months in summer (Tday=13.2h)
– 50g payload consuming 0.5W
– Flight location CH, at 500m above sea level
16/30
Introduction
Design Methodology
Sky-Sailor Design
y Meth. Applicationy Real-Time Simulation
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd Defense
Autonomous Systems LabETH Zürich, 24.09.08
Methodology application
• Sky-Sailor Layout– 3.2m wingspan
– 0.78m2 wing area (0.525m2 covered by cells)
– 14.2W for level flight (electrical)
16/30
Introduction
Design Methodology
Sky-Sailor Design
y Meth. Applicationy Real-Time Simulation
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
Real-Time Simulation
Objectives
– Validate the design
– Analyze energy flows on the airplane each second
– Rapidly see influence of parameters change
17/30
Introduction
Design Methodology
Sky-Sailor Design
y Meth. Applicationy Real-Time Simulation
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
Real-Time Simulation
Simulation of a 48 h flight– On the 21st of June
– On the 4th of August (+1.5 month)
18/30
Introduction
Design Methodology
Sky-Sailor Design
y Meth. Applicationy Real-Time Simulation
Sky-Sailor Prototype
Scaling
Conclusion
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
Sky-Sailor Prototype
19/30
Configuration3 axis glider, V-tail, constant chord
Adapted from « Avance » record airplane of W. Engel
Naturally stable
Structure
Composite materials (Carbon, Aramide, Balsa)Spar-Ribs construction method
Wingspan 3.2 m
Surface 0.776 m2
Empty Weight 0.725 kg
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototype
y Config & Structurey Aerodynamicsy Solar Generatory Propulsiony Autopiloty Modeling & Controly
Experiments
Scaling
Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
Aerodynamics
20/30
Dedicated Airfoil we3.55-9.3Nominal flight speed 8.4 m/s
Nominal flight power (2.55 kg) 9 W
Glide ratio 23.5
Vertical glide speed 0.35 m/s
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototype
y Config & Structurey Aerodynamicsy Solar Generatory Propulsiony Autopiloty Modeling & Controly
Experiments
Scaling
Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
Solar Generator
21/30
216 RWE solar cells (17% eff, ~90 W max)– encapsulated into 3 solar panels
– non reflective encapsulation
Maximum Power Point tracker– 97 % efficiency for 25 g and 90 W
Lithium-Ion battery– 250 Wh, 1.056 kgÎ 240 Wh/kg
– cycle efficiency 94.8 %
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototype
y Config & Structurey Aerodynamicsy Solar Generatory Propulsiony Autopiloty Modeling & Controly
Experiments
Scaling
Conclusion
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
Propulsion group
22/30
High efficiency Propeller from E. Schöberl– 60 cm diameter– Carbon– 85.6 % efficiency
Program created to select the best motor & gearbox combination
out of 2600 motors
Gearbox– Spur gearhead, own development
Brushless Motor (LRK Strecker)– 86.8% efficiency– Excellent cooling– Low weight
Jeti Advance 45 Opto Plus brushless controller
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototype
y Config & Structurey Aerodynamicsy Solar Generatory Propulsiony Autopiloty Modeling & Controly Experiments
Scaling
Conclusion
l
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
Autopilot
23/30
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototypey Config & Structurey Aerodynamicsy Solar Generatory Propulsiony Autopiloty Modeling & Controly Experiments
Scaling
Conclusion
• Special needs (solar panels monitoring,…)
• Extreme weight & power constraints
Î Own Control & Navigation SystemLink to videos:
http://www.sky-sailor.ethz.ch/videos.htm
M d li & C t l
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
Modeling & Control
GoalsTune controller parametersTest Navigation algorithmsEvaluate airplane capabilities
24/30
7
17
1
=
=
= + +
= + × + ×∑
∑
tot prop Li dii
tot i Li i di i
i
F F F F
M M F r F r
1
2
2
2
( , )
2
2
2
ρ
ρ
ρ
=
=
=
= ⋅
prop
li li i
di di i
i mi i i
F f x U
F C S v
F C S v
M C S v chord
[ ][ ][ ][ ]
[ ]
1 1 1 2
5 5 5 3
6 6 6 4
7 7 7 5
( , )
( ) for i=2,3,4
( , )
( , )
( , )
=
=
=
=
=
l d m i
li di mi i
l d m i
l d m i
l d m i
C C C f Aoa U
C C C f Aoa
C C C f Aoa U
C C C f Aoa U
C C C f Aoa U
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototypey Config & Structurey Aerodynamicsy Solar Generatory Propulsiony Autopiloty Modeling & Controly Experiments
Scaling
Conclusion
E i t
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André NothPhd DefenseAutonomous Systems LabETH Zürich, 24.09.08
25/30
Experiments
• Several tests with subgroups– Efficiencies increase– Weight reduction– Adding functionnalities– Safety increase
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototypey Config & Structurey Aerodynamicsy Solar Generatory Propulsiony Autopiloty Modeling & Controly Experiments
Scaling
Conclusion
• Flight tests with anon-solar proto
– Aerodynamics validation– Power consumption verification– Autopilot electronic tests– Control & Navigation tuning
• Flight tests with the Sky-Sailor– Solar charge– Long flights (>3h)– 24 hours flight
Flight videos:
http://www.sky-sailor.ethz.ch/videos.htm
h fli ht st f J 8
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André NothPhd DefenseAutonomous Systems Lab
ETH Zürich, 24.09.08
27 hours flight, 21st of June 2008
Conditions– Excellent irradiance
– Bad wind conditionsÎmore power needed during the day
Achievements– Duration: 27h05
– Distance: 874 km
– Av. speed: 8.4 m/s
– Mean power: 23+1.9W
– Eused: 675 Wh
– Eobtained: 768 Wh
25/30
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor Prototypey Config & Structurey Aerodynamicsy Solar Generatory Propulsiony Autopiloty Modeling & Controly Experiments
Scaling
Conclusion
Continuous flight proved to be feasible without
thermic or altitude gain
Scaling & Other considerations
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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Scaling & Other considerations
26/30
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor PrototypeScaling
y Down: MAVy Up: Manned & Haley Epot & Thermal
Conclusion
Down Scaling
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Down Scaling
26/30
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor PrototypeScaling
y Down: MAVy Up: Manned & Haley Epot & Thermal
Conclusion
Drawbacks
– Efficiency of propulsion group
– At low power, DC motor but no BLDC
– Efficiency of aerodynamic (low Re)
– Servos below 5 grams poor quality
– High Edensity batt not easily scalable
– Autopilot sensors limited (due to
weight, ex: no tiny GPS or IMU– Silicon solar cells scale in 2D (not 3D)
• Not flexible for low radius
• Weight percentage
– MPPT efficiency (Vdiode loss/VMPPT )
Î No 24h solar flight at MAV size, but day flight possible
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Potential Energy & Thermal soaring
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ETH Zürich, 24.09.08
Potential Energy & Thermal soaring
Two possibilities to increase flight endurance are:
– Use of altitude to store energy
+ less battery needed
- altitude variesÎ aerodynamics not optimized for a
fixed density
– Thermal soaring
+ free climbing, save energy
- require a method to detect & soar thermal
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor PrototypeScaling
y Down: MAVy Up: Manned & Haley Epot & Thermal
Conclusion
28/30
Conclusion
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Conclusion
• Methodology developed– Simple and versatile– Valid on a large range– Solid weight & efficiency models– Allows fast feasibility studies– Allows to identify bottle necks
• Prototype built
– Validation of the design– Continuous flight proven– Very good know-how acquired
29/30
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor PrototypeScaling
Conclusion
Conclusion
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Conclusion
• Scaling problems– Down: efficiencies and aerodynamics– Up: large wing structure
• Outlook
– Increase # parameters (efficiency = f(power))– Flight algorithm learning energy saving– Thermal soaring– Building: improve costs, time & robustness
29/30
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor PrototypeScaling
Conclusion
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ETH Zürich, 24.09.08
Thank you for your attention
29/30
Questions ?Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor PrototypeScaling
Conclusion
Special Thanks to:– Prof. Siegwart and the entire ASL
– Walter Engel & all the people who worked on the project
– Doctoral comity
Appendices
7/30/2019 Solar Airplane Design - PhD Slides - ETHZ - A. Noth (30.09.2008)
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Appendices
• Solar Generator– Spectrum, Albedo, Sun angle– Tday & Imax
– Best research cell efficiencies– I-V curve
– MPPT– Integration in the wing
• Energy Storage– All solutions– Energy density of fuel– Lithium-Ion battery evolution
• Propulsion Group– Motors– Propeller– Weight prediction models
• Autopilot– Schematic– Telemetry
– Power consumption– Placement– GUI (thermals)– Simulation & modeling
29/30
Introduction
Design Methodology
Sky-Sailor Design
Sky-Sailor PrototypeScaling
Conclusion
• Overall– Energy Chain– Solar Airplane: light and slow– Weight-Power-Autonomy– Methodology Resolution
– 30 Parameters– Weight distribution
• Applications– Potential applications– Sky-Sailor– MAV– Manned
– HALE– Mars
• Other– Using thermals– Sun Surfer– Design phases
– Airframe model– 27 hours flight
Solar Generator
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ETH Zürich, 24.09.08
Solar Generator
Solar Energy
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gy
Solar Spectrum
Direct, diffusedand reflected light
Angle of incidence
variation
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Solar Cells Research
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ETH Zürich, 24.09.08
Solar Cell
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MPPT
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Solar cells integration
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Structure
Energy storage
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ETH Zürich, 24.09.08
Energy Storage
Energy storage solutions
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Energy Storage
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ETH Zürich, 24.09.08
Energy density of some reactants [kWh/kg](LHV Lower heating value)
Hydrogen 33.3
Methane 13.9
Propane 12.9
Gasoline 12.2
Diesel 11.7
Ethanol 7.5
Methanol 5.6
Best 2008 LiIon Battery 0.2
Sugar 4.4
Oil (Colza,…) 10.4
10 20 300
ÎImportant to keep in mind Availability / Efficiency of converters
Lithium-Ion battery evolution
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Energy density + 6.6%/yearPrice - 17%/year
Propulsion Group
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Propulsion Group
Motors
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Propeller
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E f f i c i e
n c y
[ - ]
Designed by E. Schöberl• « Master of Prop »• Also worked on Icaré and other solarairplanes
Weight prediction modelsB hl t llP ll
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Brushless controllers
Gearboxes
Propellers
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Autopilot overview
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Telemetry
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Autopilot power consumption
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Element placement in fuselage
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Modeling & Simulation
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Overall
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Overall
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Why are solar airplanes large and slow ?
21L C S
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21
2L L C S v ρ =
Thrust T
Weight mg
21
2D D C S v ρ =
Speed v
2. Ratio between L and D is equal to CL/CD
x D
L
C C
1. Equilibrium of forces
Î the same ratio occurs between thrust and weightÎ
independent of v , it only requires Sv
2
constant
x D
L
C
C
3. Power for level flight is thus requiredP = T v = (mg / ) v D LC C ⋅ ⋅ ⋅4. A way to reduce the power is to lower the speed v Î in order to keep the lift (Sv 2 constant), S needs to be increased
Solar airplanes generally have large wings and a low speed
Weight – Power - Autonomy
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Methodology Resolution
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ctrl payload struct solar batt mppt prop m m m m m m m m = + + + + + +
( )( ) ( )( ) 1
10 11
3
21 x
0 1 7 8 9 5 6 2 7 9 5 6 3 4
a a
m a a a a a a a m a a a a a a a b b
− + + + = + + + +
The equation of the total mass is
It can be shown that it has a solution if:
N
1
1312
3
210 11 4
1 x
a a
m a m a a b b
− = +
2
12 13
4
27a a ≤
30 Parameters
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Sky-Sailor weight distributions
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Applications
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Applications
Potential Applications
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• high altitude communication platform
• law enforcement
• border surveillance
• forest fire fighting
• power line inspection
• …
Sky-Sailor
What is the influence of battery technology on the
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What is the influence of battery technology on themaximal flying altitude ?
MAV
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MAV
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Manned
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Manned
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HALE Platform
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Payload: 300 Kg
Altitude: 21’000 m
Mission time: 3 months in summer
HALE Platform
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HALE Platform
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Mars design
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Storing Potential Energy
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Using Thermals
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Sun-Surfer
Obj ti
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Sun-Surfer I
Wingspan: 0.77 meters
Weight: 115 g
P level flight: 1 W
P solar : 3 W
Sun-Surfer II
Wingspan: 0.78 meters
Weight: 190 gP level flight: 2.4 W
P solar : 8 W
Objective:reduce the scale and costdevelop low-cost solar MAVs with payload capacity of ~40 gr
Design Phases
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Airframe model
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27 hours flight
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27 hours flight
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