Conceptual and Preliminary Design of a Long Endurance Electric UAV Aerospace Engineering

129 Pages·2016·12.62 MB·English

by  Andre C. Marta

Conceptual and Preliminary Design of a Long Endurance
Electric UAV
Luís Miguel Almodôvar Parada
Thesis to obtain the Master of Science Degree in
Aerospace Engineering
Supervisor: Prof. André Calado Marta
Examination Committee
Chairperson: Prof. Filipe Szolnoky Ramos Pinto Cunha
Supervisor: Prof. André Calado Marta
Member of the Committee: Dr. José Lobo do Vale
November 2016
ii
Pelaminhafam´ılia,porterpermanecido.
iii
iv
Acknowledgments
Firstofall, Iwouldliketoexpress mygratitudetomy thesissupervisor, professorAndre´ Calado Marta,
for all technical guidance, patience and moral support throughout the period of time it took me to write
thisdocument.
Moving on to the extracurricular plan, a word of appreciation is due to the Autonomous Section of
AppliedAeronautics(S3A).Itwasthankstotheworkdevelopedatthishands-onorganizationofstudents
thatIstartedgaininginterestinmodelaircraft,whichmademelookatthisthesissubjecttwice.
Furthermore,Iwanttothankafewfriendsandacquaintancesthathelpedmethroughmyacademic
life. Borrowedclassnotes,carrides,sleeplessnightsworkingforcourseprojects,miraculouspiecesof
code,etc... allgenuinecontributionsmattered.
Finally, I must dedicate this work to my family, the foundation that allowed me to harvest a higher
education level. To my parents, for supporting me financially and emotionally, while respecting my
decisionsanddailystruggles. Tomygrandparents,fordiligentlynurturingmeovertheyearswithallthe
resiliencetheycouldpossiblyseed. Andlastbutnotleast, tomybrotherandtomysister, forbeingthe
bestdistractionsofmylife.
v
vi
Resumo
A presente tese documenta o projeto conceptual e preliminar de um ve´ıculo ae´reo na˜o tripulado de
grandeautonomiamovidoaenergiasolar. Tendoemcontapropo´sitosdevigilaˆncia, operfildamissa˜o
requerumasubidainicial,aumataxaquepermitaascender1000msobrepistaem10minutos,seguido
de voo nivelado com uma autonomia de 8 horas e um alcance de 200 km durante o equino´cio. Na
fase conceptual, va´rias configurac¸o˜es de aeronaves foram avaliadas considerando os requerimentos
da missa˜o. Recorrendo a` metodologia de um processo anal´ıtico hiera´rquico, o conceito de avia˜o com
caudaemVemotormontadonatraseiradafuselagemfoiescolhidoatrave´sdecomparac¸o˜esemparel-
hadasentreos10crite´riosdamissa˜o(Aerodinaˆmica,EstruturasePeso,Integrac¸a˜odePaine´isSolares,
Propulsa˜o,FabricoeManutenc¸a˜o,EstabilidadeeControlo,VolumedeCarga,Integrac¸a˜odeVisa˜oRe-
motana1a Pessoa,DescolagemeAterragem,eCaracter´ısticasPorta´teis)e8poss´ıveisconfigurac¸o˜es.
UmapesquisanomercadodosUAVproporcionouumaestimativainicialparaopesovazioedimenso˜es
da aeronave. Atrave´s de uma pesquisa bibliogra´fica, o sistema de comunicac¸o˜es ficou definido de
antema˜o e o sistema propulsivo tambe´m foi alvo de uma estimativa inicial. Durante o projeto prelimi-
nar, a aeronave foi redimensionada realizando um conjunto de iterac¸o˜es de ponto fixo, cujo ponto de
projeto resultante garante que e´ fisicamente poss´ıvel cumprir os requisitos do voo. Aliando mu´ltiplas
ana´lises aerodinaˆmicas, realizadas numa ferramenta computacional que suporta baixos nu´meros de
Reynolds, com a eficieˆncia apurada para o sistema de propulsa˜o, os consumos de poteˆncia de cada
fase da missa˜o foram determinados assumindo condic¸o˜es meteorolo´gicas ideais. A energia solar re-
cebidapelospaine´isfotovoltaicosinstaladosfoideterminadaparaumau´nicalocalizac¸a˜o,aplicandoum
modelo teo´rico de irradiac¸a˜o em diferentes estac¸o˜es do ano. Verificou-se que no equino´cio de Marc¸o
aautonomiaalcanc¸ouas7.5horas,enquantoquenodeSetembrooseuvalorma´ximoaumentoupara
quase 10 horas. Um conjunto das partes da aeronave foi desenhado em CAD sem detalhar soluc¸o˜es
estruturais para o seu interior. As partes desenvolvidas incluem uma asa de treˆs pec¸as com 5 metros
de envergadura, uma fuselagem composta por duas pec¸as desmonta´veis, perfazendo 1.9 metros de
comprimento,eduasmetadesindividuaisdeumacaudaemV.Oscomponentesavio´nicosedosistema
depropulsa˜otambe´mforammodeladosdeformasimplificadanointeriordaaeronave,comoso´lidosde
densidade uniforme. Uma ana´lise de estabilidade de voo foi levada a cabo, resultando numa margem
esta´ticade5.6%comC nuloemcondic¸o˜esdevoonivelado. Visionandoumfuturoprojetodetalhado,
m
oenvelopedevoocruzeirofoigeradoeadistribuic¸a˜odepressa˜onaasafoiobtida.
Palavras-chave:
UAVSolar,ProcessoAnal´ıticoHiera´rquico,PontodeProjeto,BaixoNu´mero
deReynolds,Autonomia,EnvelopedeVoo.
vii
viii
Abstract
The present thesis documents the conceptual and preliminary design of a solar long endurance Un-
manned Aerial Vehicle (UAV). Having in mind surveillance goals, the mission profile requires an initial
climb, at a rate that allows to ascend 1000 m above runway in 10 minutes, followed by cruise with an
enduranceof8 hoursanda range200kmduring theequinox. Intheconceptualstage, several aircraft
configurationswereevaluatedconsideringthemissionrequirements. ResortingtotheAnalyticHierarchy
Processmethodology,therearpusherV-tailairplaneconceptwaschosenthroughpairwisecomparisons
between10missioncriteria(Aerodynamics,StructuresanWeight,SolarPanelsIntegration,Propulsion,
Manufacturing and Maintenance, Stability and Control, Payload Volume, Remote-Person View Integra-
tion,Take-offandLandingandPortableCapabilities)and8prospectivecandidateconfigurations. AUAV
market investigation provided an initial estimate of the empty weight fraction and airframe dimensions.
Throughbibliographicresearch,thecommunicationssystemwasdefinedbeforehandandthepropulsion
system also received an initial estimate. In the preliminary design phase, the airframe was resized by
performing a set of fixed point iterations, whose resulting design point ensured it is physically possible
to fulfill flight requirements. Allying multiple aerodynamic analyses, performed on a low Reynolds num-
ber computational tool, with the ascertained efficiency of the propulsion system, power consumption
at each mission stage was determined under ideal weather conditions. The solar energy received by
the photo-voltaic arrays installed was determined in a single location applying a theoretical irradiation
modelindifferentseasonsoftheyear. ItwasverifiedthatintheMarchequinoxendurancereached7.5
hours, while in September its maximum increased to almost 10 hours. An aircraft CAD assembly was
modeledwithoutinternalairframedetail. Thedevelopedpartsincludeathree-piece5meterspanwing,
a fuselage composed by two connectable pieces, totaling 1.9 meter length, and two individual V-tail
halves. On-boardpropulsionandavionicscomponentswerealsomodeledinasimplifiedway,assolids
ofuniformdensity. Aflightstabilityanalysiswasperformed,resultinginastaticmarginof5.6%withnull
C incruiseconditions. Lookingatafuturedetaileddesign,thecruiseflightenvelopewascreatedand
m
thewingpressuredistributionwasobtained.
Keywords:
Solar UAV, Analytic Hierarchy Process, Design Point, Low Reynolds Number, En-
durance,FlightEnvelope.
ix
x