Improved Design of a High Lift System for General Aviation Aircraft

85 Pages·2015·11.26 MB·English

by  Dino Florjancic

Improved Design of a High Lift System
for General Aviation Aircraft
Master thesis
Dino Florjancic
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I D H L S
MPROVED ESIGN OF A IGH IFT YSTEM
G A A
FOR ENERAL VIATION IRCRAFT
MASTER THESIS
by
DinoFlorjancic
inpartialfulfillmentoftherequirementsforthedegreeof
MasterofScience
attheDelftUniversityofTechnology,
tobedefendedpubliclyonTuesdayAugust25,2015at1:30PM.
Studentnumber: 4317866
Tesisregistraionnumber: 039#15#MT#FPP
Supervisors: Prof.dr.ir.L.L.M.Veldhuis
Ir.D.Steenhuizen
Anelectronicversionofthisthesisisavailableathttp://repository.tudelft.nl/.
DepartmentofFlightPerformanceandPropulsion
FacultyofAerospaceEngineering•DelftUniversityofTechnology
Copyright©DinoFlorjancic
Allrightsreserved.
DELFT UNIVERSITY OF TECHNOLOGY
DEPARTMENTOF
FLIGHTPERFORMANCEANDPROPULSION
TheundersignedherebycertifythattheyhavereadandrecommendtotheFacultyofAerospaceEngineering
foracceptanceathesisentitledImprovedDesignofaHightLiftSystemforGeneralAviationAircraftbyDino
FlorjancicinpartialfulfillmentoftherequirementsforthedegreeofMasterofScience.
Dated:August25,2015
Headofdepartment:
Prof.dr.ir.L.L.M.Veldhuis
Supervisor:
Ir.DurkSteenhuizen
Reader:
Ir.W.A.Timmer

P
REFACE
Onthe19thofAugust2013IlandedattheSchipholairportforthefirsttime.Inthenexttwoyears,another22
flightswouldfollow,allowingmetomigratebetweenTheNetherlandsandSloveniainordertostudyabroad
andstillkeepintouchwithmyhome.Thisisonlypossiblebecausethedevelopmentsinaircraftengineering
have made the air travel fast, reliable and affordable. But as the aircraft industry keeps on growing expo-
nentiallyatarateof5%annually,theamountoffuelburntandgreenhousegassesemittedbytheaircraftis
growingaswell. ThereforetherearegreatchallengesremainingfortheinstitutionslikeTUDelftwhichIam
proudtohavebeenpartof,evenifjustasamastersstudent,forthelasttwoyears.Highliftsystems,thetopic
ofthisthesis,playanimportantroleinmakingtheaircraftmorefuelefficient.
TosaythatIlearnedalotduringmymastersattheTUwouldbeanunderstatement. Throughlecturesand
manyextracurriculareventstheTUgavemegreatinsightinaerospaceengineering, aswellastaughtme
a lot of useful analytical skills. I hope I also gave a small contribution back in the form of this thesis. At
thispointIwouldliketothankLeoVeldhuiswho,asachairmanoftheFlightPerformanceandPropulsion
group,approvedmyproposalforthisprojectandshowedalotofenthusiasmforit,andDurkSteenhuizen
whoservedasmydaytodaysupervisorandgavemeallthenecessaryfeedback.Asmoothcollaborationwith
thesupervisorsallowedmetofinishthisprojectintheplannedtimeframe.
TheinitialideaforthetopicoftheresearchcamefromGregorVebleofthePipistrelcompany,whoIwould
liketothankforgivingmethisopportunity.AdditionallyIwouldliketothankTineTomazic,VidPlevnikand
MihaSkof,allofthemPipistrelpersonnel,whohelpedmewithvarioustechnicaldataandadvice.
MystudyabroadwouldnothavebeenpossiblewithoutthescholarshipprogrammeoftheSloveneHuman
ResourcesDevelopmentandScholarshipFund(JavniskladRSzarazvojkadrovinstipendije),whichalmost
completelyfundedmystudyattheTUDelft.
Special thanks goes to Max Baan who offered me to print the hardcopies of the thesis while I was not in
Delft,aswellasgavemefeedbackandadvicethroughoutmytimeinthe"Kamertje1"(includingthefrequent
checkingofmyscreenforanysignsofthesis-unrelatedwebsites). Ialsoacknowledgealltheothermembers
ofthe"Kamertje1"duringmystaythereformakingtheatmospherehighlymotivational.
ImetalotofpeopleduringmystayinTheNetherlands,butonlyfewofthemIgottoknowwell.Oneofthem
isMustafaCanKaradayi,withwhomwespentmanyhoursworkingtogetherontheassignmentsaswellas
discussingcountlessrandomtopicsfromphysicstosociety. TheothersarethefellowSlovenianstudentsin
Delft,whomademefeelathomeonmanyoccasions.
Iwouldalsoliketothankmyparentsandmysisterforbeingsogenuinelyhappyduringeachofmyvisitsat
home. Thesameistrueformygrandparents,myauntsandmycousins-Ithankthemforallofthesupport
notonlyduringmystudyinDelftbutingeneral. Andaveryspecialthanksgoestomygirlfriend,Amelija,
becauseofhertrustinmeandinourrelationshipwhileIwasaway.
DinoFlorjancic
Delft,August2015
v

A
BSTRACT
Relatively high wing loading leads to increase in fuel efficiency in commercial as well as in small general
aviationaircraft,butrequiressophisticatedhighliftdevicestokeepthetake-offandlandingdistanceswithin
acceptablelimits.Highliftdevicescaninturnhaveadetrimentaleffectoncruiseperformance,andthusfuel
efficiency,intheformofadditionalparasiticdragofthehighliftsystemmechanismfairingsunderthewing.
Inaddition,theweightandcomplexityofthehighliftsystemincreaseswithitsperformance.Thepurposeof
thisresearchistoincreasethepayloadofahighlyefficientpropellerdriven4-seatergeneralaviationaircraft
byimprovingitsplainflaphighliftsystemwhiletherangestaysthesame.Thereforeadetaileddesignofthe
highliftsystemisrequired,aswellastheevaluationoftheoverallaircraftperformance.
Astudyofexistinghighliftsystemsingeneralaviationaircraftisconducted,basedonwhichapreliminary
designdecisiontoimplementasingle-slottedflapwithadroppedhingemechanismismade. Anoptimiza-
tionloopisdevelopedwithinwhichtheflapgeometryisgeneratedbasedonninedesignvariables(including
thepositionofthehingepointandtheflapdeflectionangle)andthecleanconfigurationairfoilshape.Two-
dimensionalaerodynamicanalysisofthetwo-elementairfoilsectionisperformedbytheMSEScodeatthree
differentanglesofattack.Amethodofreadingthemaximumvalueofdisplacementthicknessontheflapup-
persurfaceisimplementedtoalgorithmicallydetectseparatedflowanddiscardtheflapdesignsthatsuffer
fromseparationatlowanglesofattackinordertoavoidjumpsintheliftcurve. Three-dimensionalaero-
dynamiccharacteristicsoftheaircraftwithdeployedflapsareestimatedusingsemi-empiricalmethods.The
dragofthemechanismfairingsisalsoestimatedbyasemi-empiricalmethod.Asimpleperformancemodelis
usedtopredictthepayload,whichrepresentstheobjectivefunctionoftheoptimization. Landingandtake-
offdistancesarealsocalculatedusingtheperformanceequations. Matlab’sgeneticalgorithmandpattern
searchalgorithmareusedtoperformglobalandlocaloptimizationoftheflapgeometry.
Theresultingsingle-slottedflapdesignincreasethemaximumtake-offweightby13%whichresultsinthe
increaseinpayloadof42%. Take-offdistanceincreasesby12.5%andlandingdistanceincreasesby16.5%.
Maximumsectionalliftcoefficientisimprovedby27%withrespecttotheoriginalplainflap. Theadditional
cruisedragduetomechanismfairingsincreasesthefuelweightby3%fortherangeof1000nm. Limiting
phenomenainachievingthehighesttwo-dimensionalliftcoefficientistheburstingofmainelement’swake,
ratherthanflowseparationofftheairfoilsurface. Themethodofmonitoringthedisplacementthicknessof
theflapwakeissuccessfulinensuringthattheoptimizedflaphasnojumpsintheliftcurve.
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