1 EVALUATIONANDCOMPARISONOFHELICOPTERSIMULATIONMODELSWITH DIFFERENTFIDELITIES ATHESISSUBMITTEDTO THEGRADUATESCHOOLOFNATURALANDAPPLIEDSCIENCES OF MIDDLEEASTTECHNICALUNIVERSITY BY DEN˙IZYILMAZ INPARTIALFULFILLMENTOFTHEREQUIREMENTS FOR THEDEGREEOFMASTEROFSCIENCE IN AEROSPACEENGINEERING JULY2008 Approvalofthethesis: EVALUATIONANDCOMPARISONOFHELICOPTERSIMULATIONMODELSWITH DIFFERENTFIDELITIES submittedbyDENI˙ZYILMAZinpartialfulfillmentoftherequirementsforthedegreeof Master of Science in Aerospace Engineering Department, Middle East Technical Uni- versityby, Prof. Dr. CananO¨zgen Dean,GraduateSchoolofNaturalandAppliedSciences Prof. Dr. ˙IsmailH.Tuncer HeadofDepartment,AerospaceEngineering Dr. ˙IlkayYavrucuk Supervisor,AerospaceEngineeringDept.,METU ExaminingCommitteeMembers: Prof. Dr. CahitC¸ıray AerospaceEngineeringDept.,METU Dr. ˙IlkayYavrucuk AerospaceEngineeringDept.,METU Prof. Dr. OzanTekinalp AerospaceEngineeringDept.,METU Assist. Prof. Dr. Og˘uzUzol AerospaceEngineeringDept.,METU Assist. Prof. Dr. NilaySezerUzol MechanicalEngineeringDept., TOBBUniversityofEconomicsandTechnology Date: Iherebydeclarethatallinformationinthisdocumenthasbeenobtainedandpresented in accordance with academic rules and ethical conduct. I also declare that, as required bytheserulesandconduct,Ihavefullycitedandreferencedallmaterialandresultsthat arenotoriginaltothiswork. Name,LastName: DEN˙IZYILMAZ Signature : iii ABSTRACT EVALUATIONANDCOMPARISONOFHELICOPTERSIMULATIONMODELSWITH DIFFERENTFIDELITIES Yılmaz,Deniz M.S.,DepartmentofAerospaceEngineering Supervisor : Dr. ˙IlkayYavrucuk July2008,76pages This thesis concerns the development, evaluation, comparison and testing of a UH-1H heli- copter simulation model with various fidelity levels. In particular, the well known minimum complexitysimulationmodelisupdatedwithvarioushigherfidelitysimulationcomponents, such as the Peters-He inflow model, horizontal tail contribution, improved tail rotor model, controlmapping,groundeffect,fuselageinteractions,groundreactionsetc. Resultsarecom- pared with available flight test data. The dynamic model is integrated into the open source simulationenvironmentcalledFlightGear. Finally,themodeliscross-checkedthrougheval- uationsusingtestpilots. Keywords: helicopter,simulation,fidelity,mathematicalmodeling iv ¨ OZ GERC¸EKC¸˙IL˙IG˘˙IDEG˘˙IS¸KENHEL˙IKOPTERMODELLER˙IN˙INDEG˘ERLEND˙IR˙ILMES˙I VEKARS¸ILAS¸TIRILMASI Yılmaz,Deniz Yu¨ksekLisans,HavacılıkveUzayMu¨hendislig˘iBo¨lu¨mu¨ TezYo¨neticisi : Dr. ˙IlkayYavrucuk Temmuz2008,76sayfa Butezdeg˘is¸ikgerc¸ekc¸ilikseviyeleriolanUH-1Hhelikoptersimu¨lasyonmodelleriningelis¸tirilmesini, testinivekars¸ılas¸tırılmasınıic¸erir. Literatu¨rdeiyibilinen”minimumcomplexity”simulasyon modelininkontroldag˘ıtımı,yataykanatcıkaerodinamig˘i,rotoric¸ akıs¸ı,go¨vde,yeretkiles¸imi gibiyenibirimlerilegerc¸eklikseviyesiartırıldı. Sonuc¸laruc¸us¸ testverisiilekars¸ılas¸tırıldıve testpilotlarıtarafındansimulasyonortamındadenendi. AnahtarKelimeler: helikopter,simu¨lasyon,gerc¸ekc¸ilik,matematikselmodelleme v Tomyfamily vi ACKNOWLEDGMENTS I would like to express my sincere gratitude to Dr. ˙Ilkay Yavrucuk who supervised in all stepsofthisworkandprovidedthenecessaryresourcesofhisknowledgeandexperience. His energy,supportandguidancehelpedmetocompletethiswork. I would like to thank Prof. Dr. Cahit C¸ıray for setting the first light about helicopters in my mind during my undergraduate years. Also, many thanks to Assoc. Prof. Dr. SerkanO¨zgen for encouraging me to start my master thesis about helicopter simulation. Special thanks to Prof. Dr. OzanTekinalpandAssist. Prof. Dr. Og˘uzUzolfortheirassistanceandsuggestions. I wish to state my thanks to the Teoman O¨zmen, who has never turned down my specific requests about UH-1H helicopters and simulators located in helicopter maintenance center militarybase. IwishtostatemayendlessthankstoOnurTarımcıandS¸evketEserKubalı. Iprobablywould not be able to finish my thesis without their help about coding and integration to simulation environment. IwouldliketothankO¨zlemCeyhanandAdnanCeyhanforsharingmywhole thesis progress. I appreciate the useful discussions we had with Volkan Kargın and Hilal Erc¸in. I can not forget the assistance of Tolga Yapıcı, Tahir Turgut and Emre Altuntas¸ about latex formating. I also would like to thank Gu¨rsu Tas¸ar, Alper Ezertas¸ and Go¨khan Ahmet for always being on my side during the thesis. Thanks to Dr. Mustafa Kaya for his supports too. I would like to thank all my friends working in the same laboratory; Burcu Akın, Tuba C¸ig˘dem Elmas, Sinem Is¸ık, Zeynep C¸akır and Onur Tarımcı for supporting me whenever I needed. Also many thanks to my friends, Burcu C¸akın Erdog˘an and Bus¸ra Akay who had been far away but close enough to share my thesis progress. Special thanks to all aerospace engineeringdepartmentstafffortheirkindresponses. Finally, I would like to express my deepest thanks to my parents for their endless support throughout my life. Also, this thesis is supported by the 106M069 project of The Scientific andTechnologicalResearchCouncilofTurkey(TUBITAK). vii TABLE OF CONTENTS ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv O¨Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v DEDICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi ACKNOWLEDGMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii TABLEOFCONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii LISTOFTABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x LISTOFFIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi CHAPTERS LISTOFABBREVIATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 MATHEMATICALMODELING . . . . . . . . . . . . . . . . . . . . . . . 9 2.1 MainRotorModeling . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2 StabilizerBarModeling . . . . . . . . . . . . . . . . . . . . . . . . 18 2.3 TailRotorModeling . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.4 HorizontalTailModeling . . . . . . . . . . . . . . . . . . . . . . . 20 2.5 VerticalTailModeling . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.6 FuselageModeling. . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.7 SkidModeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.8 GroundSurfaceReactionModeling . . . . . . . . . . . . . . . . . . 24 2.9 Altitudeandthrustcoefficientupdating . . . . . . . . . . . . . . . . 26 2.10 GroundEffectModeling . . . . . . . . . . . . . . . . . . . . . . . . 27 2.11 OtherUpdates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 viii 3 TRIMMINGUSINGAFLIGHTCONTROLLER . . . . . . . . . . . . . . . 31 3.1 InnerLoopController . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.2 OuterLoopController . . . . . . . . . . . . . . . . . . . . . . . . . 33 4 SIMULATIONRESULTSANDMODELVERIFICATION . . . . . . . . . 37 4.1 TrimConditionValidation . . . . . . . . . . . . . . . . . . . . . . . 37 4.2 DynamicResponseValidation . . . . . . . . . . . . . . . . . . . . . 41 4.2.1 HoverCondition . . . . . . . . . . . . . . . . . . . . . . 42 4.2.1.1 PilotCollectiveStepInput . . . . . . . . . . 42 4.2.1.2 PilotLongitudinalCyclicStepInput . . . . . 44 4.2.1.3 PilotLateralCyclicStepInput . . . . . . . . 46 4.2.1.4 PilotPedalStepInputtoHover . . . . . . . . 48 4.2.2 60KnotsForwardFlightCondition . . . . . . . . . . . . 50 4.2.2.1 PilotCollectiveStepInput . . . . . . . . . . 51 4.2.2.2 PilotLongitudinalCyclicStepInput . . . . . 53 4.2.2.3 PilotLateralCyclicStepInput . . . . . . . . 55 4.2.2.4 PilotPedalStepInput . . . . . . . . . . . . . 57 4.3 PilotEvaluationinRealTimeSimulation . . . . . . . . . . . . . . . 58 4.3.1 IntegrationIntoaSimulationEnvironment . . . . . . . . . 58 4.3.2 PilotEvaluation . . . . . . . . . . . . . . . . . . . . . . . 60 5 CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 5.1 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 A GEOMETRYSPECIFICATIONSOFTHEUH-1HHELICOPTER . . . . . . 69 B MAINROTORINFLOWDISTRIBUTIONS . . . . . . . . . . . . . . . . . 70 B.1 LongitudinalStepInputto60KnotsTrimmedFlight . . . . . . . . . 71 B.2 LateralStepInputto60KnotsTrimmedFlight . . . . . . . . . . . . 76 ix
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