Table Of ContentImproved 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.
vii
Description:who served as my day to day supervisor and gave me all the necessary by improving its plain flap high lift system while the range stays the same. dimensional aerodynamic analysis of the two-element airfoil section is .. 3.5 MSES grid convergence study for GA(W) airfoil at α = 8° and δf = 30°.
