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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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