Helicopter Flight Dynamics (Aiaa Education Series)

680 Pages·2007·8.39 MB·English

by  G. Padfield

HELICOPTER FLIGHT DYNAMICS
The Theory and Application
of
Flying Qualities
and
Simulation Modelling
Second Edition
Gareth D. Padfield
BSc,PhD,CEng,FRAeS

HELICOPTER FLIGHT DYNAMICS

HELICOPTER FLIGHT DYNAMICS
The Theory and Application
of
Flying Qualities
and
Simulation Modelling
Second Edition
Gareth D. Padfield
BSc,PhD,CEng,FRAeS
(cid:1)C 1996,2007byG.D.Padfield
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Firstpublished1996
Secondeditionpublished2007
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Padfield,G.D.
Helicopter flight dynamics : the theory and application of flying qualities and simulation
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p.cm.
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ISBN-13:978-1-4051-1817-0(hardback:alk.paper)
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1.Helicopters–Aerodynamics. 2.Helicopters–Handlingcharacteristics. I.Title.
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Contents
Prefacetofirstedition xiii
Prefacetosecondedition xvii
Copyrightacknowledgements xxi
Notation xxiii
Listofabbreviations xxxiii
Chapter1 Introduction
1.1Simulationmodelling 1
1.2Flyingqualities 3
1.3Missingtopics 4
1.4Simpleguidetothebook 5
Chapter2 Helicopterflightdynamics–anintroductorytour
2.1Introduction 9
2.2Fourreferencepoints 10
2.2.1Themissionandpilotingtasks 11
2.2.2Theoperationalenvironment 14
2.2.3Thevehicleconfiguration,dynamicsandflightenvelope 15
Rotorcontrols 15
Twodistinctflightregimes 17
Rotorstallboundaries 20
2.2.4Thepilotandpilot–vehicleinterface 22
2.2.5Re´sume´ofthefourreferencepoints 24
2.3Modellinghelicopterflightdynamics 25
Theproblemdomain 25
Multipleinteractingsubsystems 26
Trim,stabilityandresponse 28
Theflappingrotorinvacuo 30
Theflappingrotorinair–aerodynamicdamping 33
Flappingderivatives 36
◦
Thefundamental90 phaseshift 36
Hubmomentsandrotor/fuselagecoupling 38
Linearizationingeneral 41
Stabilityandcontrolre´sume´ 42
ThestaticstabilityderivativeMw 43
Rotorthrust,inflow, Zwandverticalgustresponseinhover 46
Gustresponseinforwardflight 48
Vector-differentialformofequationsofmotion 50
viii Contents
Validation 52
Inversesimulation 57
Modellingreview 58
2.4Flyingqualities 59
Pilotopinion 60
Quantifyingqualityobjectively 61
Frequencyandamplitude–exposingthenaturaldimensions 62
Stability–earlysurprisescomparedwithaeroplanes 63
Pilot-in-the-loopcontrol;attackingamanoeuvre 66
Bandwidth–aparameterforallseasons? 67
Flyingamissiontaskelement 70
Thecliffedgeandcarefreehandling 71
Agilityfactor 72
Pilot’sworkload 73
Inceptorsanddisplays 75
Operationalbenefitsofflyingqualities 75
Flyingqualitiesreview 77
2.5Designforflyingqualities;stabilityandcontrolaugmentation 78
Impurityofprimaryresponse 79
Strongcross-couplings 79
Responsedegradationatflightenvelopelimits 80
Poorstability 80
Therotorasacontrolfilter 81
Artificialstability 81
2.6Chapterreview 84
Chapter3 Modellinghelicopterflightdynamics:buildingasimulationmodel
3.1Introductionandscope 87
3.2Theformulationofhelicopterforcesandmomentsinlevel1modelling 91
3.2.1Mainrotor 93
Bladeflappingdynamics–introduction 93
Thecentre-springequivalentrotor 96
Multi-bladecoordinates 102
Rotorforcesandmoments 108
Rotortorque 114
Rotorinflow 115
Momentumtheoryforaxialflight 116
Momentumtheoryinforwardflight 119
Local-differentialmomentumtheoryanddynamicinflow 125
Rotorflapping–furtherconsiderationsofthecentre-spring
approximation 128
Rotorin-planemotion–lead–lag 135
Rotorbladepitch 138
Groundeffectoninflowandinducedpower 139
3.2.2Thetailrotor 142
3.2.3Fuselageandempennage 146
Thefuselageaerodynamicforcesandmoments 146
Theempennageaerodynamicforcesandmoments 149