2014 uav propulsion - technion

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Solar Based Propulsion System UAV Conceptual Design (*)

Solar Based Propulsion System UAV Conceptual Design (*)

Avi Ayele*§, Ohad Gur§, and Aviv Rosen*

*Technion – Israel Institute of Technology§IAI – Israel Aerospace Industries

Avi Ayele*§, Ohad Gur§, and Aviv Rosen*

*Technion – Israel Institute of Technology§IAI – Israel Aerospace Industries

3rd Conference on Propulsion Technologies for Unmanned Aerial VehiclesJanuary 30, 2014, Technion, Haifa, Israel

(*)Ayele A., Gur O., Rosen A., "Conceptual MDO of solar powered UAV," 53rd Israel Annual Conference on Aerospace Sciences, March 6-7, 2013, Israel


Engineering DivisionEngineering & Development Group

Ragone Chart

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

Specific Energy [W-hr/kg]

Sp

eci

fic

Po

we

r [W

/kg

]

Carbon Nano Tubes

Shape Memory

Alloy

Metal Spring

Phase Change

Materials

Internal

Combustion

Engine

Fuel Cell

Flywheel

Li-Ion

Battery

Pneumatics

Synthetic Muscle

Radioisotope

Thermoelectric

Generator

Solar Panels

Ragone ChartCurtsey of Lidor A., Weihs D., Sher E.


Lidor A., Weihs D., Sher E., “Alternative Power-Plants for micro aerial vehicles (MAV),”

53rd Israel Annual Conference on Aerospace Sciences



Ragone Chart

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

Specific Energy [W-hr/kg]

Sp

eci

fic

Po

we

r [W

/kg

]

Carbon Nano Tubes

Shape Memory

Alloy

Metal Spring

Phase Change

Materials

Internal

Combustion

Engine

Fuel Cell

Flywheel

Li-Ion

Battery

Pneumatics

Synthetic Muscle

Radioisotope

Thermoelectric

Generator

Solar Panels



Lidor A., Weihs D., Sher E., “Alternative Power-Plants for micro aerial vehicles (MAV),”

53rd Israel Annual Conference on Aerospace Sciences



Firsts StepsFirsts Steps

1st “Solar” Vehicle

Sunrise II, Nov. 1975

1st Manned “Solar” Vehicle

Solar Riser, April 1979

1st Manned Solar Vehicle

Gossamer Pinguin, May 1980

André Noth, “History of Solar Flight,” Autonomous System Lab, Swiss Federal Institute of Technology, Zürich, July 2008

Crossing the English Channel

Solar Challenger, July 1981

Endurance Record, 2 Weeks Flight

Qinetiq Zephyr, July 2010



NASA HALEs (High Altitude, Long Endurance)NASA HALEs (High Altitude, Long Endurance)

Pathfinder

1994-1998

70,500 ft, 1998

b = 30m

AR=12

m=250 kg

Centurion

1997-1999

80,000 ft (goal)

b=63m

AR=26

m=860kg

Helios

1999-2003

96,800 ft, 2001

b=75m

AR=31

m=930kg

Dryden Flight Research Center Website, www.nasa.gov [cited: February 2013)

Pathfinder-Plus

1998-2002

80,200 ft, 1998

b = 37m

AR=15

m=315 kg



Main Design ChallengeMain Design Challenge

Energy Balance

Solar Panels Efficiency

Energy Storage Weight / Volume

Aerodynamics

Structure (Weight)



Main Design ChallengeMain Design Challenge

Energy Balance

Solar Panels Efficiency

Energy Storage Weight / Volume

Aerodynamics

Structure (Weight)

MDO: Multidisciplinary

Design

Optimization

Solution



Performance, Like Sausages…Performance, Like Sausages…

Power

WeightD

rag

Performance

Mission

Laws, like sausages, cease to inspire respect in proportion as we know how they are made

(John Godfrey Saxe, 1869)



Analysis ModelAnalysis Model

Solar Radiation Model

Date, Time, Location, Attitude

Aerodynamic Model

Air-Vehicle Geometry

Weight Estimation

Energy Balance

Vehicle

Weight

Drag

PolarAvailable

Power

Mission Definition

Flight

Condition

Mission

Feasibility

Power

WeightD

rag

Performance

Mission



Solar Radiation ModelSolar Radiation Model

Based on ESDU formulation

Time (date / hour)

Latitude / Longitude

Altitude

Attitude

Engineering Sheet Data Units, "Solar heating: total direct irradiance within the earth’s atmosphere,"

ESDU 69015, September 1975

August 2012 , Israel

0

200

400

600

800

1000

1200

1400

1600

0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

Time

Wat

t/S

qrm

Total Solar Irradiance Outside Earth's Atmosphere

Total Solar Irradiance at Sea Level

Horizontal Surface to the Earth

Israel Meteorological Service

Sunrise Sunset



Aerodynamic Drag EstimationAerodynamic Drag Estimation

Lift dependent drag

Only induced

Simple Oswald factor (e = 0.9)

Zero lift drag

Drag bookkeeping

Form-Factor

Interference-Factor

2

0e

1LDD C

ARCC

π+=

S

SIFFFCC iWet

iiifi0D

−−− =

1.1

244.1.1

,

2

,

=

++=

Wingi

Wingi

IF

c

t

c

tFF

( )1

0025.060

1

.,

..

.

2

...

.,

=

++=

Fusei

FuseFuse

Fuse

FuseFuseFuse

Fusei

IF

HW

L

HWLFF

Wing Fuselage

Roy T. Schemensky, “Development of an empirically based computer program to predict the aerodynamics characteristics of aircraft.

Volume 1, Empirical methods,” Air Force Flight Dynamic Laboratory, AD-780-100, November 1973



Weight EstimationWeight Estimation

Weight Bookkeeping

Structure

Propulsion system

Batteries

Solar Panel

Payload

A. Noth, "Design of Solar Powered Airplanes for Continuous Flight,"

Ph.D. Thesis, ETH, Eidgenössische Technische Hochschule Zürich,

September 2008

Motor Weight Estimation



Structure Weight EstimationStructure Weight Estimation

311.0556.1

,

005.0312.1

,

005.0312.1

,

25.01.3

,

763.8

8.225.1

19.15

44.0

−

−

−

−

=

=×

=

=

ARbm

ARbm

ARbm

ARbm

StenderStructure

RizzoStructure

RizzoStructure

NothStructure

0

100

200

300

400

500

600

700

800

900

1000

0 10 20 30 40 50 60 70 80

Actual Mass

Noth

Stender

Rizzo

Rizzo X 1.5

b, m

mS

tru

ctu

re,

kg

Pathfinder Pathfinder Plus

Centurion

Icare II

Helios



Mission DefinitionMission Definition

Sunrise

Sunset Sunset

Sunrise

70,000 ft

S.L

<70,000 ft

200 ft/min

200 ft/min



Mathematical Programming FormulationMathematical Programming Formulation

( )

( ) 0

..

min

≤

ℜ∈

xg

xfx

ts

n

f(x) – cost function

Vehicle mass

Night time altitude

Payload mass

x – design variables

Wing dimension

Battery mass

g(x) – design constraints

Energy balance



Numerical Implementation

Matlab & ESTECO modeFrontier environment

Numerical ImplementationMatlab & ESTECO modeFrontier environment



Design Variables

Cost Function

Night Time Altitude - Maximize

Total Vehicle Mass - Minimize

Design Constraint

Energy balance

Design Case ADesign Case A

100 m10 mWing Span, b

405 Aspect Ratio, AR

70,000 ft50,000 ftMinimum Cruise Altitude

1000 kg10 kgBattery mass, mBattery

Maximum ValueMinimum ValueDesign Variable



Design Case A, Pareto FrontDesign Case A, Pareto Front

mPayload = 2 kgmBattery,kg

b,kg (Diameter)

mBattery,kg

b,kg (Diameter)

Night Time Altitude, ft

Tota

l V

ehic

le M

ass,

kg



Design Case A, Pareto FrontDesign Case A, Pareto Front

mPayload = 2 kg

Bat

tery

Mas

s, m

Ba

tter

y, k

g

0

100

200

300

400

500

600

700

800

900

1000

55000 57500 60000 62500 65000 67500 70000


mBattery,kg

b,kg (Diameter)

mBattery,kg

b,kg (Diameter)


Tota

l V

ehic

le M

ass,

kg



Design Case A, Pareto Front DesignsDesign Case A, Pareto Front Designs

Win

g S

pan

, b

, m

15

25

35

45

55

65

75

85

95

105

50000 52500 55000 57500 60000 62500 65000 67500 70000


Win

g A

spec

t R

atio

, A

R

0

5

10

15

20

25

30

35

50000 52500 55000 57500 60000 62500 65000 67500 70000


Win

g A

rea,

S,

m2

0

50

100

150

200

250

300

350

50000 52500 55000 57500 60000 62500 65000 67500 70000


Str

uct

ura

l M

ass,

mS

tru

ctu

re,

kg

0

100

200

300

400

500

600

700

800

900

1000

50000 52500 55000 57500 60000 62500 65000 67500 70000




Technology ImprovementsDesign Case A

Technology ImprovementsDesign Case A

Two main technologies:

Solar panels efficiency

Nominal 22%, Improved: 40%

Batteries energy density

Nominal 350 W-hr/kgf, Improved: 500 W-hr/kgf



Technology ImprovementsTotal Mass

Technology ImprovementsTotal Mass

0

200

400

600

800

1000

1200

1400

1600

1800

2000

50000 52500 55000 57500 60000 62500 65000 67500 70000


To

tal

mas

s, k

g

η Sol. =0.22

ρ Bat. =350 W-hr/kg

η Sol. =0.4


η Sol. =0.22


η Sol. =0.4




Technology ImprovementsBattery Mass

Technology ImprovementsBattery Mass

0

100

200

300

400

500

600

700

800

900

1000

50000 52500 55000 57500 60000 62500 65000 67500 70000


Bat

tery

mas

s, k

g

η Sol. =0.22


η Sol. =0.4


η Sol. =0.22


η Sol. =0.4




Design Case BDesign Case B

100 m10 mWing Span, b

255 Aspect Ratio, AR

500 kg10 kgBattery mass, mBattery

Maximum ValueMinimum ValueDesign Variable

Design Variables

Cost Function

Payload Mass - Maximize

Total Vehicle Mass – Minimize

Two cases

Night time altitude 65 kft

Night time altitude 50 kft

Design Constraint

Energy balance

0

500

1000

1500

2000

2500

3000

3500

0 20 40 60 80 100 120

Payload Mass, kg

Req

uir

ed P

aylo

ad P

ow

er,

Watt



0

100

200

300

400

500

600

0 10 20 30 40 50 60 70 80 90 100 110

Payload Mass, kg

Night Altitude = 50,000 ft


Bat

tery

Mas

s, m

Ba

tter

y, k

g

Design Case B, Pareto FrontDesign Case B, Pareto Front

0

200

400

600

800

1000

1200

1400

1600

1800

0 10 20 30 40 50 60 70 80 90 100 110

Payload Mass, kg

Tota

l M

ass

, kg

Night Altitude 50,000 ft

Night Altitude 65,000 ft



Design Case B, Pareto Front DesignsDesign Case B, Pareto Front Designs

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 10 20 30 40 50 60 70 80 90 100 110

Payload Mass, kg

Pay

load M

ass

/ T

ota

l M

ass



0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50 60 70 80 90 100 110

Payload Mass, kg

(Pay

load

Mass

+ B

att

ery

Mass

) /

Tota

l M

ass



0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 10 20 30 40 50 60 70 80 90 100 110

Payload Mass, kg

Str

uct

ura

l M

ass

/ T

ota

l M

ass





ConclusionsConclusions

Solar UAV design is a MDO problem

Staying aloft ‘forever’ requires very big vehicles

Even for a very modest payload

Low feasibility for constant altitude HALE

Lower night time altitude is required

Crucial importance of improved technologies

Main effort: Energy storage weight and volume

Solar panels efficiency

Structure (Weight)

2014 uav propulsion - technion

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