This page intentionally left blank AIRCRAFT DESIGN AircraftDesignexplorestheconceptualphaseofafixed-wingaircraft designproject.Designinganaircraftisacomplex,multifacetedprocess that embraces many technical challenges in a multidisciplinary envi- ronment. By definition, the topic requires intelligent use of aerody- namic knowledgeto configureaircraftgeometry suited specificallyto acustomer’sdemands.Itinvolvesconfiguringaircraftshape,estimat- ing its weight and drag, and computing the available thrust from the matched engine. The methodology includes formal sizing of the air- craft,enginematching,andsubstantiatingperformancetocomplywith a customer’s demands and government regulatory standards. Associ- atedtopicsincludesafetyissues;environmentalissues;materialchoice; structurallayout;andunderstandingtheflightdeck,avionics,andsys- tems(forbothcivilandmilitaryaircraft).Costestimationandmanu- facturingconsiderationsalsoarediscussed.Thechaptersarearranged to optimize understanding of industrial approaches to aircraft-design methodology. Example exercises based on the author’s industrial experience with typical aircraft design are included. Additional sec- tionsspecifictomilitaryaircrafthighlightedwithanasteriskareavail- ableontheWebatwww.cambridge.org/Kundu Ajoy Kumar Kundu was educated in India (Jadavpur University), the United Kingdom (Cranfield University and Queen’s University Belfast),andtheUnitedStates(UniversityofMichiganandStanford University). His experience spans nearly thirty years in the aircraft industry and fifteen years in academia. In India, he was Professor at the Indian Institute of Technology, Kharagpur; and Chief Aircraft DesigneratHindustanAeronauticsLtd.,Bangalore.InNorthAmer- ica, he was Research Engineer for the Boeing Aircraft Company, Renton,andIntermediateEngineerforCanadairLtd., Montreal.He began his aeronautical career in the United Kingdom with Short Brothers and Harland Ltd., retiring from Bombardier Aerospace- Shorts, Belfast, as Chief Assistant Aerodynamicist. He is currently associated with Queen’s University Belfast. He held British, Indian, and Canadian private pilot licenses. He is a Fellow of the Royal Aeronautical Society and the Institute of Mechanical Engineers and an Associate Fellow of the American Institute of Aeronautics and Astronautics. CambridgeAerospaceSeries EditorsWeiShyyandMichaelJ.Rycroft 1. J.M.RolfeandK.J.Staples(eds.):FlightSimulation 2. P.Berlin:TheGeostationaryApplicationsSatellite 3. M.J.T.Smith:AircraftNoise 4. N.X.Vinh:FlightMechanicsofHigh-PerformanceAircraft 5. W.A.MairandD.L.Birdsall:AircraftPerformance 6. M.J.AbzugandE.E.Larrabee:AirplaneStabilityandControl 7. M.J.Sidi:SpacecraftDynamicsandControl 8. J.D.Anderson:AHistoryofAerodynamics 9. A.M.Cruise,J.A.Bowles,C.V.Goodall,andT.J.Patrick:PrinciplesofSpaceInstru- mentDesign 10. G.A.KhouryandJ.D.Gillett(eds.):AirshipTechnology 11. J.Fielding:IntroductiontoAircraftDesign 12. J.G.Leishman:PrinciplesofHelicopterAerodynamics,2ndEdition 13. J.KatzandA.Plotkin:LowSpeedAerodynamics,2ndEdition 14. M.J.AbzugandE.E.Larrabee:AirplaneStabilityandControl:AHistoryoftheTech- nologiesthatMadeAviationPossible,2ndEdition 15. D.H.HodgesandG.A.Pierce:IntroductiontoStructuralDynamicsandAeroelasticity 16. W.Fehse:AutomaticRendezvousandDockingofSpacecraft 17. R.D.Flack:FundamentalsofJetPropulsionwithApplications 18. E.A.Baskharone:PrinciplesofTurbomachineryinAir-BreathingEngines 19. D.D.Knight:NumericalMethodsforHigh-SpeedFlows 20. C.Wagner,T.Hu¨ttl,andP.Sagaut:Large-EddySimulationforAcoustics 21. D.Joseph,T.Funada,andJ.Wang:PotentialFlowsofViscousandViscoelasticFluids 22. W.Shyy,Y.Lian,H.Liu,J.Tang,andD.Viieru:AerodynamicsofLowReynoldsNum- berFlyers 23. J.H.Saleh:AnalysesforDurabilityandSystemDesignLifetime 24. B.K.Donaldson:AnalysisofAircraftStructures,SecondEdition 25. C.Segal:TheScramjetEngine:ProcessesandCharacteristics 26. J.Doyle:GuidedExplorationsoftheMechanicsofSolidsandStructures 27. A.Kundu:AircraftDesign 28. M.Friswell,J.Penny,S.Garvey,andA.Lees:FundamentalsofRotorDynamics 29. B.Conway(ed):SpacecraftTrajectoryOptimization Aircraft Design Ajoy Kumar Kundu Queen’sUniversityBelfast CAMBRIDGEUNIVERSITYPRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo, Delhi, Dubai, Tokyo Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521885164 © Ajoy Kundu 2010 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published in print format 2010 ISBN-13 978-0-511-67785-4 eBook (NetLibrary) ISBN-13 978-0-521-88516-4 Hardback Cambridge University Press has no responsibility for the persistence or accuracy of urls for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. Contents ListofSymbolsandAbbreviations pagexxi Preface xxxi RoadMapoftheBook xxxv TheArrangement xxxv SuggestedRoutefortheCoursework xxxix SuggestionsfortheClass xli UseofSemi-empiricalRelations xlii 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Overview 1 1.1.1 WhatIstoBeLearned? 1 1.1.2 CourseworkContent 1 1.2 BriefHistoricalBackground 2 1.3 CurrentAircraftDesignStatus 7 1.3.1 ForcesandDrivers 8 1.3.2 CurrentCivilAircraftDesignTrends 9 1.3.3 CurrentMilitaryAircraftDesignTrends∗ 11 1.4 FutureTrends 11 1.4.1 CivilAircraftDesign:FutureTrends 12 1.4.2 MilitaryAircraftDesign:FutureTrends∗ 14 1.5 LearningProcess 15 1.6 UnitsandDimensions 17 1.7 CostImplications 17 2 MethodologytoAircraftDesign,MarketSurvey,and Airworthiness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.1 Overview 19 2.1.1 WhatIstoBeLearned? 20 2.1.2 CourseworkContent 20 2.2 Introduction 20 2.3 TypicalDesignProcess 21 ∗ ThesesectionsarefoundontheCambridgeUniversityWebsiteatwww.cambridge.org/Kundu v vi Contents 2.3.1 FourPhasesofAircraftDesign 23 2.3.2 TypicalResourcesDeployment 25 2.3.3 TypicalCostFrame 26 2.3.4 TypicalTimeFrame 26 2.4 TypicalTaskBreakdowninEachPhase 26 2.4.1 FunctionalTasksduringtheConceptualStudy (Phase1:CivilAircraft) 28 2.4.2 ProjectActivitiesforSmallAircraftDesign 29 2.5 AircraftFamiliarization 31 2.5.1 CivilAircraftandItsComponentConfigurations 31 2.5.2 MilitaryAircraftandItsComponentConfigurations∗ 33 2.6 MarketSurvey 33 2.7 CivilAircraftMarket 35 2.7.1 AircraftSpecificationsandRequirementsforThreeCivil AircraftCaseStudies 36 2.8 MilitaryMarket∗ 39 2.8.1 AircraftSpecifications/RequirementsforMilitaryAircraft CaseStudies∗ 39 2.9 ComparisonbetweenCivilandMilitaryAircraftDesign Requirements 40 2.10 AirworthinessRequirements 41 2.11 CourseworkProcedures 42 3 AerodynamicConsiderations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 3.1 Overview 43 3.1.1 WhatIstoBeLearned? 43 3.1.2 CourseworkContent 44 3.2 Introduction 44 3.3 Atmosphere 46 3.4 FundamentalEquations 48 3.5 AirflowBehavior:LaminarandTurbulent 50 3.5.1 FlowPastAerofoil 55 3.6 AircraftMotionandForces 56 3.6.1 Motion 56 3.6.2 Forces 57 3.7 Aerofoil 58 3.7.1 GroupingsofAerofoilsandTheirProperties 59 3.8 DefinitionsofAerodynamicParameters 62 3.9 GenerationofLift 63 3.10 TypesofStall 65 3.10.1 GradualStall 66 3.10.2 AbruptStall 66 3.11 ComparisonofThreeNACAAerofoils 66 3.12 High-LiftDevices 67 3.13 TransonicEffects–AreaRule 68 ∗ ThesesectionsarefoundontheCambridgeUniversityWebsiteatwww.cambridge.org/Kundu Contents vii 3.14 WingAerodynamics 70 3.14.1 InducedDragandTotalAircraftDrag 73 3.15 AspectRatioCorrectionof2DAerofoilCharacteristicsfor3D FiniteWing 73 3.16 WingDefinitions 76 3.16.1 PlanformArea,S 76 W 3.16.2 WingAspectRatio 77 3.16.3 WingSweepAngle,(cid:1) 77 3.16.4 WingRoot(c )andTip(c )Chord 77 root tip 3.16.5 WingTaperRatio,λ 77 3.16.6 WingTwist 78 3.16.7 High/LowWing 78 3.16.8 Dihedral/AnhedralAngles 79 3.17 MeanAerodynamicChord 79 3.18 CompressibilityEffect:WingSweep 80 3.19 WingStallPatternandWingTwist 82 3.20 InfluenceofWingAreaandSpanonAerodynamics 83 3.20.1 TheSquare-CubeLaw 84 3.20.2 AircraftWettedArea(A )versusWingPlanform W Area(S )8 5 w 3.20.3 AdditionalVortexLift 87 3.20.4 AdditionalSurfacesonWing 87 3.21 FinalizingWingDesignParameters 89 3.22 Empennage 90 3.22.1 H-Tail 90 3.22.2 V-Tail 91 3.22.3 TailVolumeCoefficients 91 3.23 Fuselage 93 3.23.1 FuselageAxis/Zero-ReferencePlane 93 3.23.2 FuselageLength,L 94 fus 3.23.3 FinenessRatio,FR 94 3.23.4 FuselageUpsweepAngle 94 3.23.5 FuselageClosureAngle 94 3.23.6 FrontFuselageClosureLength,L 94 f 3.23.7 AftFuselageClosureLength,L 95 a 3.23.8 MidfuselageConstantCross-SectionLength,L 95 m 3.23.9 FuselageHeight,H 95 3.23.10 FuselageWidth,W 95 3.23.11 AverageDiameter,D 95 ave 3.23.12 CabinHeight,H 96 cab 3.23.13 CabinWidth,W 96 cab 3.23.14 PilotCockpit/FlightDeck 96 3.24 Undercarriage 96 3.25 NacelleandIntake 96 3.26 SpeedBrakesandDiveBrakes 96 viii Contents 4 AircraftClassification,Statistics,andChoicesfor Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 4.1 Overview 98 4.1.1 WhatIstoBeLearned? 99 4.1.2 CourseworkContent 99 4.2 Introduction 99 4.3 AircraftEvolution 100 4.3.1 AircraftClassificationandTheirOperational Environment 101 4.4 CivilAircraftMission(Payload-Range) 104 4.5 CivilSubsonicJetAircraftStatistics(SizingParametersand RegressionAnalysis) 105 4.5.1 MaximumTakeoffMassversusNumberofPassengers 106 4.5.2 MaximumTakeoffMassversusOperationalEmptyMass 107 4.5.3 MaximumTakeoffMassversusFuelLoad 108 4.5.4 MaximumTakeoffMassversusWingArea 109 4.5.5 MaximumTakeoffMassversusEnginePower 111 4.5.6 EmpennageAreaversusWingArea 112 4.5.7 WingLoadingversusAircraftSpan 113 4.6 CivilAircraftComponentGeometries 113 4.7 FuselageGroup 114 4.7.1 FuselageWidth 114 4.7.2 FuselageLength 117 4.7.3 Front(NoseCone)andAft-EndClosure 117 4.7.4 FlightCrew(FlightDeck)CompartmentLayout 121 4.7.5 CabinCrewandPassengerFacilities 121 4.7.6 SeatArrangement,Pitch,andPosture(95thPercentile) Facilities 122 4.7.7 PassengerFacilities 123 4.7.8 CargoContainerSizes 124 4.7.9 Doors–EmergencyExits 125 4.8 WingGroup 126 4.9 EmpennageGroup(CivilAircraft) 128 4.10 NacelleGroup 130 4.11 SummaryofCivilAircraftDesignChoices 133 4.12 MilitaryAircraft:DetailedClassification,EvolutionaryPattern, andMissionProfile∗ 134 4.13 MilitaryAircraftMission∗ 134 4.14 MilitaryAircraftStatistics(SizingParameters–Regression Analysis)∗ 135 4.14.1 MilitaryAircraftMaximumTake-offMass(MTOM) versusPayload∗ 135 4.14.2 MilitaryMTOMversusOEM∗ 135 4.14.3 MilitaryMTOMversusFuelLoadM∗ 135 f 4.14.4 MTOMversusWingArea(Military)∗ 135 ∗ ThesesectionsarefoundontheCambridgeUniversityWebsiteatwww.cambridge.org/Kundu