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Design of Solar Powered Unmanned Biplanes for HALE Missions

  • Vittorio Cipolla
  • Aldo Frediani
Part of the Springer Optimization and Its Applications book series (SOIA, volume 66)

Abstract

Some of the results of a research about the design of solar powered Unmanned Aerial Vehicles (UAVs) to be used in High Altitude Long Endurance (HALE) missions are given. The proposed airframe architecture has a biplane layout, conceived to face the most significant challenge for this kind of aircraft: to fly at high altitude, under wintertime conditions and for a wide range of latitude angles. The Solar Powered Biplane (SPB) concept is presented as well as the related design procedure, which can be used to define UAVs for different purposes and mission conditions, such as loiter altitude, latitude and year’s day. A presentation of the design method is given, providing details about models for Aerodynamics, Flight Mechanics, energy balance evaluation, structural analysis and propulsion system sizing. As a particular result of this research, an SPB configuration capable to meet some of the requirements indicated by the US Defense Advanced Research Projects Agency (DARPA) as goals of the HALE flight, is illustrated. Such aircraft, which can operate in each year’s day, at latitudes up to 45° and altitudes up to 18 000 m, is described in details, and a flexibility analysis for different mission conditions is carried out.

Keywords

Unman Aerial Vehicle Defense Advance Research Project Agency Winter Solstice Defense Advance Research Project Agency Trail Edge 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

AM

Air Mass

ACV

Aerodynamic centre of vertical surfaces

b

Wingspan

B

Balancing Mass Fraction

CG

Centre of gravity

CP

Centre of pressure

CL

Lift coefficient

CD

Drag coefficient

E

Energy

EA

Aerodynamic efficiency

Gh

Non-dimensional horizontal distance between wings

Gv

Non-dimensional vertical distance between wings

H

Altitude

Hcruise

Cruise altitude

m

Pitch moment

mac

Mean aerodynamic chord

M

Mass

MoS

Margin of longitudinal stability

nz

Vertical load factor

NP

Neutral point

NV

Number of vertical wings

Nwt

Number of wing trunks on half wingspan

P

Power

Pmin

Minimum required power

Preq

Required power for cruise flight

Re

Reynolds number

SH

Horizontal wing area

SR

Ratio between rear wing and front wing areas

SV

Vertical wing area

T

Mission endurance

V

Speed

Vcruise

Cruise speed

\(V_{P_{\mathrm{min}}}\)

Minimum required power speed

VV

Vertical tail volume

Greek Symbols

α

Angle of attack

β

Angle of sideslip

γ

Angle of climb

ΔTth

Endurance variation threshold

ΔMth

Mass variation threshold

εg

Energy Density

Φ

Latitude angle

η

Efficiency

ρ

Density

Subscripts

ac

Accumulator

st

Structure

lg

Landing gear

m

Motor

pay

Payload

ch

Charge (ref. to accumulators)

dis

Discharge (ref. to accumulators)

sa

Solar array

sc

Solar cell

p

Propeller

f

Flight

d

Devices

in

Input or initial

out

Output

th

Threshold

Acronyms

AFOV

Angular Field of View

DARPA

Defense Advanced Research Projects Agency

DIA

Department of Aerospace Engineering

ERAST

Environmental Research Aircraft and Sensor Technology

FEM

Finite Element Method

HALE

High Altitude Long Endurance

IFOV

Instantaneous Field of View

IRS

Intelligence, Reconnaissance and Surveillance

LE

Leading edge

NASA

National Aeronautics and Space Administration

SPB

Solar Powered Biplane

TE

Trailing edge

TLC

Telecommunication

UAV

Unmanned Aerial Vehicle

VLM

Vortex-Lattice Method

Notes

Acknowledgements

My thanks go to all the people who worked with me on this topic at Department of Aerospace Engineering and, in particular, to the former students Paolo Rossi, Maurizio Borghi, Pasquale Cantisani, Luca Montanelli, Andrea Isoppo and Matteo Moisè. I also want to thank Prof. Aldo Frediani and Prof. Giuseppe Buttazzo for giving me the opportunity of presenting this work at the “Variational Analysis and Aerospace Engineering II” Workshop.

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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  1. 1.Department of Aerospace EngineeringUniversity of PisaPisaItaly

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