cyclic & collective by shawn coyle
DESCRIPTION
Cyclic & Collective by Shawn Coyle This unique book, written from the prospective of the pilot provides a detailed, yet easy to understand overview of the theory and practice of helicopters. It covers nearly all aspects of learning to fly a helicopter, from basic theory through to Autopilots. Detailed explanations are provided for both beginner and advanced pilots on performance, handling and the mechanics of helicopters. This book has two sections:The beginner section has the fundamentals of helicopter theory of aerodynamics, performance and flying are covered in sufficient detail for the beginning helicopter pilot. Examples are based around a piston engine helicopter and a given from a cockpit perspective.The advanced section is for professional pilots, as well as those who want to know more about helicopters and how they work. It covers turbine engine helicopters with more advanced systems. Everything you could ever want to know about helicopters but didn’t know where to look. This book satisfies in one volume the needs of all helicopter pilots, from beginner through instructor to advanced pilots. It nicely bridges the gap between engineering textbooks and what pilots and engineers need to know. Book available from www.EagleEyeSolutionsLLC.comTRANSCRIPT
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Why Two “Books”? iiiWhy Did I Write This Book? iv
Keeping Things in Perspective ivStandard Disclaimers iv
Political Correctness ivAim of every flight iv
Terms Used vDedication v
Introduction to the Second Edition vCorrections and Additions vi
1 Some FundamentalsMath and Physics Revisited 1
Vectors 1Newton’s Laws 1
Newton’s First Law 1Newton’s Second Law 1Newton’s Third Law 2
Other Physics and Maths terms 2Momentum and Inertia 2Speed 2Velocity 2Acceleration 2Equilibrium 2
Vectors, Resultants and Resolving 3Moments and Couples 3
Moments 3Couple 4
Balance of Forces 4Dimensional Correctness 4Distance and Time 4
Mass, Force, Energy and Work 4Mass 4Force 5Energy 5Work 6Power 6
Graphs and Such 6Putting Together Some of the Basics 7
2 Introduction to Helicopter AerodynamicsTerms Used 11
Zero Airspeed vs. Zero Groundspeed Hover 11Center of Gravity (CG) 11Aerodynamic Terms 11Angle of Attack 14Lift 17
More Discussion of Lift 19Formula for Lift 20Drag 21Zero Angle of Attack 22
3 The Rotor BladeGeneral 25
Axes of the Blades 25How Lift Gets to the Hub 26Drag on the Whole Blade 27Blade Flapping 27A Brief Moment to Study Law 29
4 More Basics of the HelicopterGeneric Helicopter 31The Whole Rotor 31
Telling the Blades Apart 31Airframe Relative Airspeed 32
Relative Airflow and Disk 33Forward Flight and Dissymmetry of Lift 33
Cyclical Change of Pitch 34Flapping to Equality 35
Total Lift from the Disk 36Tip Path Plane 36
Drag at Different Parts of the Disk 37Total Drag on the Disk 37Keeping the Blades Clean 37
Flapback or Blowback 38Rotor Heads and Components 38
Fully Articulated Rotor Hub 38Control of the Rotor 39
The Swashplate 39Phasing of Control Inputs 39Rotating Scissors Assembly 41So What? 41
Tail Rotors 41Anti-Torque Control 41
5 Air, Wind and WeatherIntroduction 43
What Temperature is That? 43Where do we Measure Vertical Distance From? 43
International Standard Atmosphere 43Standard Day 43Pressure Altitude 43Non-Standard Day 44Density Altitude 44Importance of Understanding Density Altitude 45The How and Why of Density Altitude 46Relative Humidity 46
Wrong Information 47More Wrong Information 47Wind! 48
Knowing The Wind from Natural Sources 48Wind Speed Change with Height 49Wind Direction Change with Height 50
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Wind Shift and Turbulence 50A Lesson from the Birds 50
Weather 50So What do We Need to Worry About? 51An Example 51
6 Basic Helicopter PerformanceIntroduction 53Airframe Performance Defined 53
Measuring Performance 53Hover performance 53
Out of Ground Effect (OGE) 54In Ground Effect (IGE) 54How Does Ground Effect Happen? 54Using a Crane to Lift Instead of an Engine 55
Power Required vs. Density Altitude 56Hover Ceilings 56
Forward Flight Performance 56Power Required vs. Airspeed 56What You Can’t Do with This Chart 57The ‘Backside’ of the Power Curve 57
Low Airspeed Power Required 58Climb and Descent Performance - Simplified 59
Flight Manual Charts 59V Airspeeds 59Load Factors 60
7 Balance and WeightThe Importance of Center of Gravity 61
Calculating Weight and Balance 62Balance 62
Datum Forward of the Nose. 63Datum At Rotor Mast 64
Weight and CG Diagram 65Weight vs. Loaded Moment Method 65Yet Another Way to Measure CG 65Longitudinal CG 66Lateral CG 66Vertical CG 67
Balance of Forces 68General 68
Balance of Forces in the Hover 69Side View Four Basic Forces 69Top View Balance of Forces - Torque Reaction 69Rear View of Balance of Forces 69
Trim 71Balance of Forces - Forward Flight 71Side View of Balance of Forces 72Top View of Balance of Forces Forward Flight 72Inherent Sideslip 73Rear View of Balance of Forces - Forward Flight 73
8 The Aerodynamics of AutorotationIntroduction 75Autorotation Defined 75
Conditions Necessary for Autorotation 75Lift Vectors Again 76Effect of Forward Flight 78
How the Blade Works in Autorotation 78NR in Autorotation Descent 78Another Use for the Autorotation RPM Chart 79Effect of Density 79Effect of Weight 79
9 Instruments and Warning SystemsAirframe Instruments 81Sideslip and Side Force 81
What the Slip Ball Measures 81What is Sideslip? 82Slip Strings 84
Engine Transmission and Rotor Instruments 84NR Warnings 84Transmissions and Gearboxes 85Transmission Oil Temperature and Pressure 85Chip Detectors 85
10 The Piston EngineIntroduction 87Principles of Operation 87
Components 87Basics of Carburation 88
Vaporization 89Piston Engine Helicopter Instruments 89
Manifold Pressure 90Starting 91Clutches 91
Centrifugal (or Automatic) Clutch 91Idler or Manual Clutch 91
Free–Wheel Units 92Piston–Engine Helicopter Power Control 92
Rotor RPM 92Power Output 92Measuring Piston Engine Helicopter Power 93
Same Engine in a Seized Wing Airplane 93Carburetor Icing 94
Why do Carburetors Ice Up? 94More Carburetor Icing Explanation 94Effects of Icing 95Symptoms of Carburetor Icing 95Carburetor Heat 96Prevention of Carburetor Ice 97
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Mixture Control 97Throttle Handling 98Over-Pitching 98
Wrong Side of Torque Curve 99Only on Some Piston Engine Helicopters 99Coning Angle and Over-pitching 99Turbine Engines and Over-Pitching 100
Throttle Co–relators 100Fuel Injection 100Piston Engine Governors 101
How Does the Governor Work? 101Performance Rules of Thumb for Piston Engines 101Turbochargers 101Other Components of the Engine 102
Oil and Oil Pumps 102Generators 102Fans 102Fuel Systems 102
Operation of the Piston Engine 103 Pre-Start 103Fuel Draining 103Starting 103Lift-Off 103In-Flight 104
11 Dear StudentInstructors - What They Know and Don’t Know 105Personality Differences 105The Essential Pre-Flight Briefing 106Checklists 106For Those Who Make Checklists 106
All Those Gages and Clocks! 106Blindfold Cockpit Checks 106
For Both Instructor and Student 107Transfer of Control 107Following Through on the Controls 107
Where to Look 107Outside, Mostly 107Look Around 108Collision Course 108
Post-flight 108Walkaround 108
12 Before You Strap In…Introduction 109Prior to Lift-off 109Terms Used 109
Pre-Flight Actions 110Pre-Flight checks 110Walk-Around checks 110Start–Up checks 111
Energy and the Rotor System 111Pre-Lift-off Checks 111
Holding the Controls 112Light Training Helicopters 112Control Pressure, Not Control Movement 112Function of Controls 112
Effects of Controls 113Downwash 114Hand Signals 114
13 Helicopter Flying - The BasicsGeneral Introduction 117
Forward Flight 117Effects of Controls in Forward Flight 117
Cyclic stick 117Collective lever 118Pedals 118
Summary of Effects of Controls 119Attitude Flying 119
Cruise 120Changing Airspeed in Level Flight 121
Smooth Airspeed Changes 121Back Side of The Power Curve 122Two Airspeeds for the Same Power! 122
Climbs and Descents 122Turns 123
A Note 123Gentle Turns (up to 20�Angle of Bank) 123Nose Drop 123Increased Power 123A Changed Sight Picture 123Slip Ball 124Practice 124Medium Turns (20 to 45� Angle of Bank) 124Steep Turns (Greater than 45� Angle of Bank) 124
Developing a ‘Seat of the Pants’ Sense 124
14 The Divine Art of HoveringIntroduction 125
To the Hover! 125Hovering More Easily 125Vertical References 125Aim of Hovering 126
Concepts of Hovering 126Hover - Zero Groundspeed vs. Zero Airspeed 126Effects of Controls - Hover and Low Airspeed 126Forward Flight and ‘Low Airspeed’ 127Overcontrolling in the Hover 128Cyclic Stick as a Position Controller 129
NR Control 130Hovering With A Purpose 130
Partial Control Technique 130
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Lots of Things to Do 130Specific Exercises for Learning Hovering 131
Taxing Along a Line 131Changing Height While Hovering 131Changing Heading 132
Moving Around 132Hovering with Different References 132
Back to Flying 132Turns in the Hover 133
No Wind 133With Winds 133
In the Low Speed Environment 134Useful Training Exercises 134General Handling in the Hover 135
Taxing to the Side or Rear 136Ground Taxing Skid Helicopters 136
15 ‘Twixt Heaven and Earth,Introduction 137
Slipping and Crabbing 137Transition to Forward Flight 137Ground Track 138Translational Lift 138
Other Transitions to Forward Flight 138Cushion Creep 139Steep Climbout 139
Running Takeoff 139Why Running Takeoffs? 139How It Works 139How to Carry Out a Running Takeoff 140Cautions on the Running Takeoff 140
“Maximum Performance Climbout” 140An Example of Getting Caught 140
Downwind Transition 141Turns After Transition 141Approach and Touchdowns 141
Transition Back to the Hover 142Learning to Judge… 142
…Perspective 143…Rates of Closure 144
‘Normal’ Approach 144Suitable Rate of Descent 144Adding Power 144
Fast Approaches 145Steep Approach 145The No-Hover Touch Down 145
Downwind Approach to the Hover 146Approaches with Turns 146
Line-Up 146Turning into a Downwind Approach 146
VIP Approaches - Mastery of the Machine 146
Running Landing 147Traffic Patterns or Circuits 147
What do Traffic Patterns Teach / Show 148Confined Areas 148
16 Lift-off and TouchdownIntroduction 151
Flat Pitch to Light on the Skids 151How Do you Know ’Light on the Skids’? 151From ’Light on the Skids’ to the Hover 152Airborne! 152Lift-off out of Wind 153
Touching Down From The Hover 153Flat Surfaces 153Don’t Overcontrol 154A Neat Trick for Smooth Touch Downs 154
Sloping Surfaces 155Tail Rotor Side Thrust 156While You’re On the Sloping Ground 156Wind Across the Slope 157Lift-off from the Slope 157Nose Upslope / Downslope 157
One Last Word About Sloping Ground 157
17 Introducing EmergenciesEmergencies - General 159Critical Emergencies 159
Dual Concurrence (or Double Checking) 159What Emergencies Can Happen 160
Unanticipated Emergencies 160As a Student 160Chip Detectors 160Realistic Emergencies 160Where to Handle Emergencies 161
18 Engine Failures for BeginnersGeneral 163
Simulated vs. ‘Real’ Engine Failures 163Warming-up for Autorotations 163Vertical Landings 164
Engine Failures in the Hover 164Judging Collective Lever Application 164High Hover Engine Failures 165Self-Initiated Engine Failures Hover 165Quick Stops 165The Flare 166So What Should You Do? 167Flare Effectiveness 167
Collective Check - Why It Works 168Coupling of Forces in Leveling Helicopter 168
Power Recovery Autorotations 168Getting Back to the Hover 169
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‘Real’ Autorotations 170Eyes Out of the Cockpit! 170
Autorotative Performance 171Some Final words 171
Some Words on The Height-Velocity Curve 171
19 Peculiarities of the HelicopterIntroduction 173Loss of Translational Lift 173Vortex Ring State 174
Impossible Descent Conditions 175Not Just in Descent 175Demonstrating Incipient Vortex Ring State 175Uncommanded Attitude Changes 176Making the Situation Worse 176Recovery 176Wrong Advice 176The Why of Vortex Ring State 177Why The Symptoms? 177
Rollover 177Static Rollover 178Dynamic Rollover 178Dynamic Rollover on Landing 179Dynamic Rollover on Takeoff 179Action in Event of Dynamic Rollover 180
Retreating Blade Stall 180Symptoms 181
Blade Sailing 181
20 Flight Manuals, Rules and RegulationsWhy? 183The Civilian Flight Manual 183
Sections of the FM 183Emergency Definitions 184Notes, Cautions and Warnings 184Procedural Words 185Performance Data 185No Altimeter Correction Charts 185Flight Manual Supplements (FMS) 185Weight and Balance Information 186Manufacturer’s Data 186Individualized Copy of the FM 186
Some Philosophical Words about the Civilian FM 186More Philosophy… 187
Certification Basis 187Reasons for Rules 188
Two more Pet Peeves 188Reasons for Limitations 188
Another Way of Thinking About Limitations 189Side Wind, Sideward Flight and All That 189
Is it a Limit Because Its in the Limitations Section? 189Power Ratings and Limitations 190
The Military Flight Manual 190Visual Flight Rules (VFR) 190
V Speeds 191
21 MiscellaneousWhere the Pilot Sits 193Radios and Air Traffic Control 193
Negative Radio 193Safety Statistics 194
Ground Handling Wheels 194Safety for Others 194Going Solo 194Cross Country Flying 195Single Seat and Ultralight helicopters 195
Inexperienced Pilots Shouldn’t Be Flying Them 195Get A Private Pilot’s License First 196Get Experience in Several Different Types 196
General Words of Advice 196Shutdown 196
22 For the Professional Helicopter Pilot / InstructorFor the Professional Helicopter Pilot 199
Helicopter Pilots Are Different 199Legal Implications 199Maintenance 199Service Difficulty Reports (SDRs) 200Your Part in Safety 200Experience 200Care and Feeding of Passengers / Customers 200
Make a Decision 200Philosophy of Instruction 201Measuring or Predicting Pilot Performance 201More Philosophy 201Preflight Briefing 202Preflight Inspection 202Walkaround 202
Concepts of Controls 202Cyclic 202Collective 202Throttle 202Pedals 202
Looking Outside 202Limitations 203
Following Through 203Checklists 203Questions and Tests 203
When the Students Ask Questions 203
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What are you Really Trying to Teach? 203Even More Philosophy 203Specific Exercises 204
Trusting the Student 204Space Awareness 204
Flying by the Seat of the Pants 204Written Tests 205
23 Advanced Helicopter AerodynamicsReview 207
Hover 207Review of Lift and Drag 207
Airfoils 207Non-symmetrical Airfoils 207Lift and Drag 207Lift to Drag Ratio 208Changing NR 208Changing Density Altitude 208
Blade and Segment Aerodynamics 209Blade CG location 209AoA Changes due to Flapping 209AoA, Lift and Center of Pressure 210
Pitching Moments 211Symmetric Section 211Non-symmetric Section 212Why the Fuss about Pitching Moments? 212
Blades 212Blade Root Cutout 212Blade Tip Shapes 213Twist 213Taper 213Twist and Taper - Again 213Lift to Drag Ratio Again 214
Disk Aerodynamics 214Solidity 214Why 2 Blades May be More Efficient than 4 215AoA and the Disk 215Advance Ratio 215VNE and True Airspeed 216Retreating Blade Stall Again 216Coning Angle Again 216Transverse Flow Effect or Inflow Roll 216Stick Migration 217
Tail Rotors 218Location on Fuselage 218Size, Direction of Rotation 218Aerodynamics of the Tail Rotor 219
24Flight Controls and Rotor HeadsGeneral 221
Tip Anhedral 221
Blade Inertia 221More Reasons for Lead–Lag Motion 221Hook’s Joint Effect 221Other Phase Angles 222
Rotor Heads 223Lead–Lag Dampers 223Types of Drag Dampers 223Droop Stops / Flap Restrainers 224Droop Stop Pounding 224Lubrication 225
Disk Axes 225Shaft Axis 226Control Axis 226Yet Another Disk Axis 226
Hinges 227Flapping Hinge Offset 227Hinge Arrangements 228Delta–Three Hinges 228Elastomeric Bearings 229Hingeless Rotor Heads 229
New Rotor Heads 230The Teetering Rotor Head 230
Stabilizer Bars 231Flap or Hub Restraining Springs 232
Hiller Control System 233Robinson R-22 and R-44 Hub. 233MD Series Rotor Head 233Height of Hub Above the CG 233
Blade Lag Angle 233Negative Pitch 234
25 Advanced PerformanceGeneral 235Factors Affecting Performance 235
Power Loading 235Induced Velocity 236
Mach Number Effects 237Hover Performance and Altitude 237Surface Effect on Hover Performance 237Vertical Drag 238Another Look at Hover Performance 238
Typical Civil FM Performance chart 239Level Flight Performance 240
Indicated Airspeed and True Airspeed 240Collective Angle vs. Airspeed 240Power vs. Collective Angle 240
Peculiarities of Low Airspeed IGE 241Another Look at Power Required to Hover 241Rotor Efficiency 242Ground Vortex Roll Up 242Low Airspeed Power Required - Again 243
Range 244
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Range Improvements with Altitude 246Headwind and Tailwind Effects 246Point of No Return 247Equal Time Point 248What If Something Goes Wrong? 249
Endurance 249Radius of Action 250How to Trick A Navigation System 250Payload vs. Radius of Action 251
Climb and Descent Performance 251Climbs 252Best Angle of Climb Airspeed 252Descent Performance 253
Whizz Wheels 253Rules of Thumb 254
26 Other ComponentsGeneral 257Fuel Systems 257
Fuel Valves 257Fuel Pumps 257Low Fuel Warning Systems 257Other Parts of the Fuel System 258When is the Fuel Gauge Reading Correctly? 258Pounds or Gallons? 258Fuel Quality 258Fuel Drains and Living in the Field 259Fuel Jettison 260
Transmissions and Drive Shafts 260HUMS 261Electrical Systems 261
External Power 261Generators 261Batteries 262DC–Based Electrical Systems 262AC–Based Electrical Systems 262Electrical Failures 263Circuit Breakers 263When a Circuit Breaker ‘Pops’ 264
Hydraulic Systems 264Reasons For Hydraulics 264Typical Hydraulic System 264Unpressurized Reservoirs 265Hydraulic Emergencies 265
De-Ice / Anti-Ice systems 265De-Ice vs. Anti-Ice 266
Landing Gear 266General 266Skids 266Wheeled Undercarriage 266Retractable Landing Gear 268Off-level Landings 268Wheel Brakes 268
Skis 268Full Length Skis 269Bear Paw Skis 269Skis on Mud 269
Floats 269Fixed Floats 269Boating! 269Start-up / shutdown 269Spray 270Taxing on Water 270Liftoff and Touchdown from the Water 270Following the Waves 270Off-Level Touchdowns on Water 270Lift-off and Touchdown from the Ground 270Other Effects of Fixed Floats 271Emergency Floats 271Use and Problems 271
Fire Detection and Suppression 271Heating and Ventilation 272Seats 272Compasses 272Windshield Wipers 273
27 Advanced Helicopter FlyingSo How Do We Fly a Helicopter? 275
Driving a Car Explained 275Compensation 275
Flying a Helicopter – Hovering 276Cruising Flight Example 276Other Cue–Related Problems 277
Why are Helicopters Difficult to Fly? 277Slow Response Explained 278Cross Coupling 279Different Responses from the Pedals 279
How to Hold the Controls 279Cyclic 279Overcontrolling 280Collective 280Pedals 280
Helicopter Pilots are Easy… 280Artificial Control Feel or Trim Systems 281
Control Forces 282Collective Release 284Fuselage Attitudes 284Pedals Again 284
The Other Way ‘Round 284
28 More InstrumentsPitot Systems 287
Altimeters 288Corrections to the Altimeter in Cold Weather 288
Static Port Locations 289
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So What? 289What Can be Done About This? 290
LORAS (LOw aiRspeed System) 290LASSIE 290RAH-66 Commanche System 290General Comment on Low Airspeed Systems 290
Another Reason for Low Airspeed Systems 291Miscellaneous Instruments 292
Outside Air Temperature Gages 292Radar Altimeters 292Waves and Radar Altimeter 292Vertical Gyroscopes and Attitude Indicators 292
Entering the Digital Era 293Too Much Accuracy 293But Some Good News Too... 293
29 The Turbine EngineIntroduction 295Turbine Engines are Different! 295Typical Free Turbine Engine 295Ratings and Limitations of Engines 297
Difference between Ratings and Limitations 297How Long is Each Limit Good For? 297Cycles 297Measuring Temperature 297
Density Altitude vs. Pressure Altitude and OAT 297Less Power in Cold Temperatures 299Effect of Humidity on Turbine Performance 299Compressor Stalls 300Two Correct Answers Don’t Make a Third… 300Turbine Engine Instruments 301Torquemeters 302Use of the Torquemeter 304
Governing systems 304Reasons for Installing Governors 305Droop! 305Static Droop 306Oscillating Governors and Hysteresis 307Transient Droop 307Hydro–mechanical Governors 308
Electronic Fuel Controls 309FADEC 309What Has All This Got to Do With FADECs? 309Failures of Digital Fuel Controls 310Practical Benefits of FADEC 311Change of the Pilots Point of View 311Duplication of Sensors 311Some Improvements Possible? 311Manual Control of the Turbine Engine 311Question Time 312Tail Rotors, Governors and Free Drinks 312Differences from Piston Engine 312Transient Overtorques 312
Turbine Engine Power Monitoring 313Topping Checks 314Trend Monitoring Checks 314
Automatic Relight vs. Manual Air Starts 315Engine–Related Items 316
Intake Protection Systems 316Anti-Icing vs. De-Icing 316Bleed Air Systems 316Bleed valves 317Heaters 317Air Conditioning 317Performance Effects of Bleed Air Systems 317Starting Against the Rotor Brake 318
Turbine Engine Cool-Down 318Emergency Systems 319
Fixed Shaft Turbine Engines 319
30 Advanced Engine FailuresGeneral 321Autorotations 321
Sensory Deprived, Multi-Variable Maneuver 321The Big Picture 321
Where to Practice Autorotative Landings 322Pre-Nominate the Landing Spot 323Autorotations ‘En–Route’ 323
Closer Look of Autorotative Performance 323Energy and Autorotations 325Cone of Possible Areas 326Variations on the Theme 326
Zero–Airspeed Autorotations 326Reverse Cone of Energy 327Landing Site is Straight Ahead 328Three Basic Locations 329Kinetic Energy in the Flare 330Why Try the Variations? 331Other Situations with Respect to the Landing Spot 332Combinations! 333
Intervention Delay Time 333Run-Down Time of the Engine 334
Height Velocity (HV) Curves 334Ignoring A Part of Most HV Curves 335So What’s Missing about the HV Curve? 335Development of the HV Curve 336Miscellaneous Points About the HV Curve 337Another Type of Autorotation 337
31 Advanced EmergenciesGeneral 339Tail Rotor Problems 339
Loss of Thrust 339Loss of Thrust in the Hover 340
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Loss of Thrust in Forward Flight 340Loss of Control of Tail Rotor Thrust 340Diagnosis of the Situation 340Slip Ball Just Touching Right Side 341Slip Ball Fully Against Right Side 341Slip Ball Just to the Right of Center 341
Fires 342Fires in the Cockpit 342
Not All Emergencies are in the Book 342Some Emergencies have Other Implications 342
When to Inflate Pop-out Floats 342To Those Who Write Emergency Procedures 343Emergencies Caused by Vibrations and Noise 343
32 Multi-Engine HelicoptersGeneral Introduction 345Terms 345Other Differences 346
Why are AEO and OEI Limits Different? 346Power Matching - Non–FADEC Engines 347Left Side vs. Right Side 348
OEI Performance 349Level Flight 349Best Angle of Climb Airspeed (Again) 350
Engine Failures in Multi-Engine Helicopters 351Engine–Related Emergencies 351Training Mode In FADEC Engines 353
Category A or Category B? 353Common Points About Category A 354Using Everything You’ve Got 355Different Profiles 355Approach and Landings 356Use of Contingency Power 357General Criteria for Takeoff Techniques 357
Heliport Takeoff Techniques 357Vertical Climb 357Back-Up Technique 358‘Sideways Slide’ Technique 358Where to Practice Single Engine Techniques 358
33 Stability and Control of the HelicopterWeight and Balance 361
Weight and CG Calculations 361Weight and Balance Effects 362
Inherent Sideslip 363Cross–Coupling of CG Effects 363Keel Area Ratio, or Weathercock Effect 364Fixed Floats Effect on Stability and Control 364Flight Controls 365
Friction Systems on Cockpit Controls 365
Viscous Damping of Control Systems 365Control Mixing 366
Equations of Motion 366Control Margin / Limitations on Controls 366
Head and Mast Bending Moments 366Longitudinal Cyclic 367Forward Cyclic 367Aft Cyclic 367Lateral Cyclic 367Up Collective 367Down Collective 367Tail Rotor 368
Lesser Known Effects 368Cross–Coupling 368Lock Number 368Rotor Head Type Effect on CG Range 369
Solving Aerodynamic Problems 369Wings 369Rudders 370Horizontal Stabilizers 370Vertical Stabilizers 370End Plates 370Gurney Flaps and Blunt Trailing Edges 370Tail Boom Strakes 371More Aerodynamic Fixes 371
How We Control the Helicopter 371
34 Further Peculiarities of The HelicopterIntroduction 373Vibrations 373
Types Of Vibrations 373Determining The Type of Vibration 373Sources 374Solutions to Vibrations 376Solving Track and Balance Problems 378
Ground Resonance 378On Start-up 379Resonance During Landings or Takeoff 380
Tail Rotor Control 380Loss of Tail Rotor Effectiveness 381
Wingovers or Crop Duster Turns 382Rapid Rolling 385Underslung Loads 385
Knowing How Much it Weighs 385Why No Cargo Hook Weighing Devices? 386Watching the Load 386Problems 387CRAP Method of Load Obedience 387Weird Underslung Loads 387Flight Path Planning 388Emergencies With Underslung Loads 388Training For Underslung Loads 388
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Automatic Flight Control Systems and Underslung Loads 388Uncommanded Jettison of Underslung Loads 389
High Altitude Flying 389Icing 389
Why is Icing So Bad? 390Snow 391Flying in Your Own Dust 391Mast Bumping 391
Causes for Mast Bumping 392Too Much Sideslip 393Other Causes of Mast Bumping 393What to Do In the Event of Mast Bumping 393Training to Prevent Mast Bumping 393
Design Eye Point 394
35 Other Helicopter TypesBrief history 395
Coaxial 395Tandem 396Synchrocopter or Intermeshing Rotors 397
Coanda Effect 398Main Blades 398Tail Boom 398
Tip Jets 398Kaman Servo–Flap Controls 399Replacing the Tail Rotor 400
Fenestron/Ducted Tail Rotor 400NOTAR 401
Other Types 401
36 Night and Instrument FlyingIntroduction 403Night Flying 403Engine Failures at Night 404Night Vision Goggles (NVG) 404The Myth of Night VFR 404
Instrument Flying 405IFR Flight Envelope 405Why is Helicopter IFR Difficult? 405Disorientation 406Useful Instrument Flying Exercises 406Inadvertent IMC 407
Autorotations at Night, in Clouds, etc. 407Instrument Flying Rules (IFR) 408
GPS and IFR 408Helicopter Only Approaches 409
37 Automatic Flight Control SystemsIntroduction 411
Definitions 411Why install an AFCS? 411Hierarchy of an AFCS 412AFCS and the Big Picture of Control 412Internal vs. External Conditions 413Components of An AFCS 413Series Actuator 415Parallel Actuators 416Combined Systems 417
Types of AFCS 417Rate Damping Systems 417Stability Augmentation System (SAS) 418Pilot Commanded Inputs 418Retrimming 419Stability and Control Augmentation Systems (SCAS). 419Attitude Based Stabilization Systems 420Hybrid Systems 421
Automatic Trim Systems 421AFCS ‘Upper’ Modes 421Definition Problems 422
Attitude Datum Re-Adjustment 422Heading Hold and Coordinated Turns 423
Hover and Low Speed 423Forward Flight 423In-between Airspeeds 423
Autopilots 424Basic Autopilot. 424Operational Autopilot. 424Altitude or Height Hold 424Radio/Radar Altitude Hold 425Speed Hold in the Low Airspeed Region 425Programmed Maneuver 425Complex Helicopter AFCS 426Automatic Transition to the Hover 427Transition from Cruise to Hover 427Radio Coupled Operations 428
Advanced Concepts 428Side Arm Controllers 428
Failures of the AFCS 429Minimum Height for Engaged AFCS 429AFCS Disconnect Switches 429
38 Miscellaneous MusingsType Ratings 431
How To Survive 431Technical Examinations 431
Minimum Equipment Lists (MEL) 431Using GPS Intelligently 432
How Best to Use the Magic 432Myths of the Helicopter 433
’Tail Rotor Stall’ 433‘Pendulum Effect’ 433
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’Stick Reversal’ 433Torque Limiters 434Health, etc. 434
Smoking 434Fluids, Bodily 435Stress 435Glasses 435
Safety General 435Personal Equipment 435
Helmets 435Immersion Suits 436
The Helicopter is Not a Winch or Bulldozer 436Good Examples vs. Bad Examples 437
What Good Pilots Do 437Simulators 438
Learning to Say No 438Noise 439
Definitions
1 Bibliography
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