Engineering.design.handbook.helicopter.engineering.part.I

AD/A-002 007 ENGINEERING DESIGN HANDBOOK. HELICOPTER ENGINEERING. PART ONE. PRELIMINARY DESIGN Army Materiel Command Alexandria, Virginia 30 August 1974

DISTRIBUTED BY:

National Technical Iufnatou Service U. S. DEPARTMENT OF COMMERCE

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PAMPLET

AMCP 706.201

'0yba" IDEC 18 1974

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ENGINEERING DESIGN

HANDBOOK0HELICOPTER ENGINEERINGR*ptoducd by

NATIONAL TECHNICAL INFORMATION SERVICEUS Departmenit of Commere. Sprtigfield, VA. 22151

PART ONE PRELIMINARY DESIGN.AAPpro%,;d for ' , ! "

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HEADOUARTERS, U.S. ARMY MATERIEL COMMAND AUGUST 1974Reproduced From Best Available Copy

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"5001 AMC PAMPHLET No. 706-201

DEPARTMENT OF rHE ARMY HEADQUARTERS UNITED STATES ARMY MATERIEL COMMAND Eisenhower Ave, Alexandria, VA 22333 30 August 1q74 ENGINEERING DESIGN HANDBOOK HELICOPTER EVI'lNEERING, PART ONE PRELIMINARY DESIGN

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PaarahTABLE

OF CONTENTSLIST OF ILLUSTRATIONS ......................................... LIST OF TA BLES .................................................. FO R EWOR D ...................................................... PREFACE ........................................................ CHAPTER 1 INTRODUCTION CHAPTER 2 MISSION EFFECTIVENESS

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xxxi xlv xlvii xlviii

, 2-1 2-1 2-1 2-2 2-2 2-3 2-3 2-4 2-4 2-5 2-5 2-5 2-5 2-6 2-8 2-9 2-10 2-I1 2-11 2-13 2-13 2-13 2-13 2-13-. . -14 2-14 2-15 2-15 2-16

2-1 2-2 2-2.1 2-2.1.1 2-2.1.2 2-2.2 2-2.3 2-2.3.1 2-2.3.2 2-3 2-3.1 2-3.1.1 2-3.1.2 2-3.1.2.1 2-3.1.2.2 2-3.2 2-3.3 2-3.3.1 2-3.3.2 2-44 2-4.1 2-4.2 24.32-4.4

INTROD UCTION ................................................. MILITARY SYSTEM REQUIREMENTS AND MISSION EFFECTIVENESS MILITARY SYSTEM REQUIREMENTS ............................ Operations Research (OR) ........................................ Budgetary Considerations ........................................ D ESIG N CYCLE ................................................. MISSION-EFFECTIVENESS EQUATION ........................... Operational Factors ............................................. Econom ic Factor ................................................ OPERATIONAL FACTOR ANALYSIS ............................... M ISSION READINESS ........................................... Mission Capability (M C) ......................................... Availability .................................................... R eliability .................................................... M aintainability ............................................... SURVIVAPTLITY ................................................ PERFORM NCE ................................................ Performatice Requirements ....................................... Performance Effectiveness ........................................ ECONOMIC ANALYSIS ............................................ GENERA L ...................................................... ELEMENTS OF ECONOMIC ANALYSIS ........................... . FORMS OF CRITERIA ...........................................COST ANALYSIS ................................................

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2-4.4.1 2-4.4.1.1 24.4.1.2 2-4.4.1.3 24 .4.1.4

Cost Concepts .................................................. Life Cycle Cost ............................................... Incremental Cost .............................................. Real Resource Utilizaticn ....................................... Joint Costs ........ ..........................................

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OF CONTENTS (Continued)Page Other Cost Concepts ............................ Cost Estimation ..........................................

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2.4.4.2.1 2-4.4.2.22-4.4.2.3

Data Development ....................................... CER Display Formats ........................................CER Derivation ..............................................

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2-4.4.2.42-4.5

Use of C ERs .................................................SIMULATION MODELING: AN EXAMPLE ........................

2-17 2.17 2-18 2-182-19

2-5

LIST OF SYM BOLS ................................................ REFERENCES ................................................CHAPTER 3 PERFORMANCE

2-21 2-22

3-1 3-1.1 3-1.2 3-2 3-2.1 3.2.1.1 3-2.1.1.1 3-2.1.1.2 3-2.1.i.3 3-2.1.1.4 3-2.1.1.5 3-2.1.1.6 3-2.1.1.7 3-2.1.1.8 3-2.1.1.9 3-2.1.1.10 3-2.1.2 3-2.1.2.1 3-2.1.2.1.1 3-2.1.2.1.2 3-2.1.2.1.3 3-2.1.2.2 3-2.1.2.2.1 3-2.1.2.2.2 3-2.1.2.2.3 3-2.1.2.2.4 3-2.1.2.2.5 3-2.1.2.2.6 3-2.1.3 3-2.1.4 3-2.2 3-2.2.1 3-2.2.2 3-2.2.3 3-2.2.3.1

INTRODUCTION ................................................. WORKING STATES OF A ROTOR ................................ POWER REQUIRED FOR LEVEL FLIGHT ........................ AERO DYNAM ICS ................................................. BASIC ANALYTICAL METHODS ................................. H overing Flight ................................................. M om entum Theory ............................................ Figure of M erit ............................................... Blade Element Theory ......................................... Tip Loss Factor ............................................... Vortex Theory-Three-dimensional Considerations .................. Theoretical Three-dimensional Prediction Method .................. Em pirical Prediction M ethod .................................... G round Effect ................................................ Vertical Dcag/Thrust Recovery .................................. Power Train Effects ........................................... Forw ard Flight ................................................. Energy M ethods ....................................... Induced Pow er ............................................... Profile Pow er ................................................. Parasite Power ................................................ Blade Elem ent Theory ......................................... W heatley M ethod ............................................. .................... Iterative Procedure ....................... Blade Stall .................................................. N um erical M ethods ........................................... Graphical M ethod-NASA Charts ................................ Radial Flow Corrections ....................................... Tandem -rotor Interference . ...................................... F~xed Aerodynamic Surfaces ...................................... COMPOUND CONFIGURATIONS ............................... Speed Capability of Helicopters ................................... Prelim inary Design Considerations ................................. Selection of Configuration Parameter% .............................. W iag ........................................................

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3-1 3-1 3-2 3-2 3-2 3-3 3-3 3-4 3-4 3-6 3-6 3-7 3-7 3-11 3-12 3-14 3-14 3-14 3-15 3-17 3-18 3-19 3-19 3-20 3-20 3-21 3-21 3-22 3-23 3-26 3-2o 3-20 3-27 3-28 3-28

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AMCP 706-201f rTABLE

OF CONTENTS (Continued)Page R otor ....................................................... Auxiliary Propulsion ........................................... Torque Balancing and Directional Control ........................ Compound Helicopter Performance ................................ Wing/Rotor Lift Sharing ....................................... Calculating Procedure for Power Required ........................ Autorot-ion of a Compound Helicopter .......................... WIND TUN NEL TESTING ....................................... Objectives ...................................................... Support of a Project ............................................ Airframe Drag and Stability Studies .............................. Powered M odels .............................................. Dynam ic M odels .............................................. Special M odels ................................................ Two-dimensional Airfoil Tests ................................... Testing of Actual Hardware ..................................... Model Design Considerations .................................. M odels Without Rotors ........................................ M odels With Rotors ........................................... Rotor Design ................................................. Rotor Control Systems .........................................Rotor Power Supply ...........................................

'\'-dParagraph3-2.2.3,2 3-2.2,3.3 3-2.2.3.4 3.2.2.4 3-2.2.4.1 3-2.2.4.2 3-2.2.4.3 3.2.3 3-2.3.1 3-2.3.2 3.2.3.2.1 3-2.3.2.2 3.2.3,2.3 3-2.3.2.4 3.2.3.215 3-2.3.2.6 3-2.3.3. 3-2.3.3.1 3-2.3.3.2 3-2.3.3.2.1 3-2.3.3.2.23-2.3.3.2.3_

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3.29 3-30 ,.30 3-32 3.32 3-32 3.33 3-33 3-33 3.33 3-34 3-35 3-35 3-35 3-36 3-36 3-36 3-36 3-37 3-37 3-373-37

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3-2.3.3.2.4 3-2.3.43-2.3.5 3-2.3.5.1

Instrum entation ............................................... Test Procedures .................................................Data Reduction ................................................ W ind Tunnel W all Corrections ..................................

3-37 3 403-40 3-40 :

3-2.3.5.23-2.3.6 3-2.3.6.1 3-2.3.6.2 3-3 3-3.1 3-3.1.1 3-3.1,2 3-3.1.2.1 3-3.1.2.2

Presentation of Results .........................................Other Related Tests ............................................. Rotor Whirl Tower ............................................ Download Test Facilities ....................................... PROPULSION .................................................... PROPULSION SYSTEM ANALYSIS ............................... Propulsion Techniques ........................................... Gas Turbine Engine Characteristics ................................ Cycle Description ............................................. Specific Fuel Consumption (SFC) ................................

3-403-41 3-41 3-41 3-42 3-42 3-42 3-43 3-43 3-44

3-3.1.2.3 3-3.1.3 3-3.1.3. i 3-3.1.3.2 3-3.1.3.3 3-3.1.3.4 3-3.1.3.5 3-3.1.3.63-3.1.4

Specific Power ................................................ Process A nalysis ................................................ Inlet ....................................................... ..................... Compressor ............................ C om bustor ................................................... T urbine ...................................................... Exhaust Duct ................................................ Other Considerations ..........................................Partial Power Cycle Analysis .....................................

3-44 3-45 3.45 3-45 3-46 3-47 3-47 3-473-48

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3-3.1.5 3-3.1.5.1 3.3.1.5.2 3-3.2

R eaction Svstem s ............................................... Hot G as Cycle ................................................ Tip Jet ..................................................... ENGINE CHARACTERISTICS AND SELECTION

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3-49 3-50 3.51 3-51 iii

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AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph 3.3.2.1 3.3.2. 1.1 3-3.2.1.3 3-3.2.2 3-3.2.2.1 Basic Considerations ............................................ Gas Turbine Engine ........................................... Coupled and Free Power Turbine Engines .......................... Cycle Modifications ........................................... Selection of Design Point Cycle Parameters ......................... Partial Power Operation ....................................... Analytical Design ............................................. Control System ................................... ...... Simple Control System .................................. Variable-geometry Control System ............................... ROTOR AND PROPELLER ANALYSIS ............................ Rotor C onfigurations ............................................ Rotor Types ................................................. Rotor Hub Geometry .......................................... Rotor Control Systems ......................................... Elem ents of Rotor M otion ...................................... Characteristics of Rotors ....................................... Fully A rticu!ated Rotors ....................................... Two-bladed Teetering Semirigid Rotors ........................ M odified Two-bladed Rotors .................................... Rigid or Hingeless Rotors ...................................... Other Rotor System Considerations ....... ....... ...... . Page 3.51 3.52 3-52. 3-53 3.56 3-56 3.57 3-.. 57 3-58 3-5 3-59 3.59 3-60 3-60 3-65 3.67 3-67 3-068 3-69 3-69 3-70 ,'*

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"3-3.2.2.23-3.2.3 3-3.2.3.1 3-3.2.3.2 3-3.3 3-3.3.1 3.3.3.1.1 3-3.3.1.2 3-3.3.1.3 3-3.3.1.4 3-3.3.1.5 3-3.3.1.5.1 ,:3-3.3.1.5.2 3-3.3.1.5.3 3-3.3.1.5.4 3-3.3.1.6

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3-3.3.2' 3-3.3.2.1 3-3.3.2.2 3-3.3.2.3 3-3.3.2.4 3-3.3.2.4.1 3-3.3.2.4.2 3-3.3.2.4.3 3-34 3-3.4.1 3-3.4.1 . 1

Propeller Selection

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3.713.71 3-71 3-71 3-72 3-72 3-73 3-74 3-75 3-78 3-80

Propeller Types .............................................. Helicopter Application ......................................... A nalytical Procedures .......................................... Propeller Selection Procedure ....... ........................... Basic Considerations ........................................... D efinitions ................................................... Performance Calculation Method ................................ OTHER PROPULSIVE DEVICES .................................. Propeller Propulsion ............................................. Prim ary Propulsion ............................................

3-3.4.1.23-3.4.2 3-3.4.3 3-3.4.4 3-4 3-4.1 3-4.1.1 3-4.1.1.1 3-4.1.1.2 3-4.1.1.3 3-4.1.1.3.1 3-4.1..3.2 3-4.1.1.4 3-4.1.2 3-4.1.2.1 3-4.1.2.1.1 iv

Tail Rotor ..................................................Shrouded Propeller Propulsion .................................... Turbofan and Turbojet Propulsion ................................. Augm entation Systems ........................................... HELICOPTER PRELIMINARY DESIGN STUDY ..................... PARAMETRIC ANALYSIS ................. ................. Optimization in Helicopter Design ................................. Objective Functions ............................................ C onstraints ................................................... Optimization Techniques ..... ................................. M aximum Seeking M ethods ..................................... Graphical Techniques .......................................... Suboptim ization ........................... ................... Basic Relationships for Parametric Analysis ......................... Engine Performance Relationships ............................... Altitude Dependence of Power Output ............................

3-803-83 3-86 3-87 3-90 3-90 3-90 3-90 3-9 1 3-92 3-92 3-92 3-92 3-92 3-93 3-93

AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph 34.1.2.1.2 3.4.1.2.1.3 3-4.1.2.2 3-4.1.2.2.1 3-4.1.2.2.1.1 3-4.1.2.2.1.2 3-4.1.2.2.1.3 3-4.1.2.2.1.4 3-4.1.2.2.2 3-4.1.2.2.3 3-4.1.2.2.4 3-4.1.2.2.5 3-4.1.2.2.6 3-4.1.2.2.6.1 3-4.1.2.2.6.2 3-4.1.2.2.6.3 3-4.1.2.2.6.4 3-4.1.2.3 3-4.1.2.3.1 3-4.1.2.3.2 3-4.1.2.3.3 3-4.1.2.4 3-4.1.3 34.1.3.1 3-4.1.3.1.1 3-4.1.3.1.2 34.1.3.1.3 34.1.3.1.4 3-4.1.3.2 3-4.1.3.2.1 3-4.1.3.2.2 3-4.1.3.2.3 34.2 3-4.2.1 34 .2.1.1 34.2.1.2 3-4.2.2 3-4.2.2.1 3-4.2.2.2 34.2.2.2.1 34 .2.2.2.2 34 .2.2.2.3 34.2.2.2.4 3-4.2.2.2.5 3-4.2.2.2.6 3-4.2.3 3-4.2.3. 1 ( 3-4.2.3.2 " 3-4 , .2.3.2.1 Temperature Dependence of Available Power ...................... Specific Fuel Consumption ...................................... Helicopter Power Requirements ................................. M ain Rotor Power ............................................ Main-rotor Induced Power ...................................... Main-rotor Profile Power ....................................... Parasite Power ................................................ Power Requirements for Tandem-rotor Configurations .............. Control Power ................................................ Accessory Power .............................................. Auxiliary Propulsive Power ..................................... Gear and Transmission Power Losses ............................. Total Helicopter Power Requirement ............................. Hover Power Required Out-of-ground Effect (OGE) ................ Hover Power Required In-ground Effect (IGE) .................... Power Required in Forward Flight ............................... Power Required to Climb ....................................... Fuel Requirements ............................................ Fuel Flow in Hover .......................................... Fuel Flow in Foiward Flight ................................... Fuel Flow in Climb ........................................... Helicopter Weight-estimating Relationships ........................ Techniques of Configuration Selection .............................. Feasible Configurations ......................................... Installed Power and Tip Speed Selection .......................... Available Fuel Weight Ratio .................................... Required Fuel Weight Ratio ................................. .. Fuel Weight Ratio Method ..................................... Optim ization ... ............................................ Minimum Weight and Minimum Size Configurations ................ Minimum Cost Configurations ................................ Cost Effectiveness ............................................. MISSION PERFORMANCE ....................................... Hover Ceiling ................................................... G eneral ...................................................... Method of Analysis ............................................ Payload ....................................................... G eneral ...................................................... Definition of Weights .......................................... Takeoff Gross Weight .......................................... Em pty W eight ................................................ Basic Weight ................................................. Fixed Useful Load ............................................ Operating W eight ............................................. Useful Load .................................................. M ission Profile ................................................. M ission Profile Definition ...................................... Mission Profile Elements .................................... W arm up ..................................................... Page 3-93 3-93 3-93 3-94 3-94 3-95 3-95 3-95 3-96 3-96 3-96 3-97 3-97 3-97 3-99 3-99 3-99 3-100 3.100 3-100 3-100 3-101 3-101 3-101 3-101 3-102 3-102 3-103 3-104 3-104 3-104 3-104 3-104 3-105 3-105 3-106 3-107 3-107 3-107 3-107 3-109 3-109 3-109 3-109 3-110 3-110 3-110 3-1 10 3-110

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AMCP 706-201

TABLE OF CONTENTS (Continued) "Paragraph3-4.2.3.2.2 Hover At Takeoff .............................................Clim b to Cruise Altitude ....................................... Cruise at Constant A ltitude ..................................... Descent to Landing Site ........................................ H over at Landing Site ......................................... Reserve A llowance ............................................ External Load M ission ......................................... Effect of Altitude on Payload-range Capability ..................... R ange ......................................................... Specific Range Parameter Computation ........................... Variation W ith Gross W eight ................................... Range Index M ethod .......................................... Effect of Altitude and Gross Weight on Range ..................... Effect of W ind on Range Capability .............................. Ferry Range Capability and Range Extension ...................... Range Parameter in Generalized Form ........................... Breguet Range Equation ........................................ Endurance ..................................................... Analysis Method .............................................. Effect of Gross Weight and Altitude on Endurance ................. Breguet Endurance Equation .................................... Rate of Climb-Maximum and Vertical ............................ Basic Considerations ........................................... Forward Clim b ............................................... Service and Combat Ceilings .................................... Time, Fuel, and Distance to Climb ............................... Vertical Clim b ................................................ Takeoff and Landing ............................................ G eneral ...................................................... Takeoff Performance ........................................... A cceleration ....... .......................................... R otation ..................................................... C lim b ....................................................... Landing Performance .......................................... A pproach .................................................... R otation ..................................................... D eceleration .................................................. AIRSPEED-ALTITUDE LIMITS ................................... G eneral ....................................................... Definitions ..................................................... Power Constraints .............................................. Structural Constraint ............................................ Stability Constraints ............................................. Maneuverability and Controllability ................................ SPECIAL CONSIDERATIONS ...................................... AUTOROTATIONAL CHARACTERISTICS ........................ Basic Mechanism of Autorotation .................................. Entry into Autorotation .......................................... Calculation of the Rate of Descent in Autorotation .................... Page

3-1103.111 3.111 3.112 3-112 3-112 3-1 13 3-113 3-1 13 3-113 3-118 3-1 18 3-119 3-120 3.120 3-123 3-123 3-126 3-127 3-127 3-127 3-130 3-130 3-130 3-133 3-133 3-133 3-137 3-137 3-140 3-140 3-140 3-141 3-144 3-144 3-145 3-145 3-146 3-146 3-146 3-147 3-147 3-150 3-150 3-151 3-151 3-151 3-152 3-154

"3.4.2.3.2.33-4.2.3.2.4 3-4.2.3.2.5 3.-4.2.3.2.6 3-4.2.3.2.7 3-4.2.3.3 3.4.2.3.4 3-4.2.4 3-4.2.3.1 3-4.2.4.2 3-4.2.4.3 3.-4.2.4.4 3-4.2.4.5 3-4.2.4.6 3-4.2.4.7 3.4.2.4.8 3-4.2.5 3-4.2.5.1 3-4.2.5.2 3-4.2.5.3 3-4.2.6 3-4.2.6.1 3-4.2.6.2 3-4.2.6.3 3-4.2.6.4 3-4.2.6.5 3-4.2.7 3-4.2.7.1 3-4.2.7.2 3-4.2.7.2.1 3-4.2.7.2.2 3-4.2.7.2.3 3-4.2.7.3 3-4 .2.7.3.1 3-4.2.7.3.2 3-4.2.7.3.3 3-4.3 3-4.3.1 3-4.3.2 3-4.3.3 3-4.3.4 3-4.3.5 3-4.3.6 3-5 3-5.1 3-5.1.1 3-5.1.2 3-5.1.3 v:

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AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph 3-5.1.3.1 3-5.1.3.2 3-5.1.4 3-5.1.5 3-5.1.6 3-5.1.6.1 3-5.1.6.2 3-5.2 3.5.2.1 3-5.2,2 3-5.2.3 3-5.2.4 3-5.3 3-5.3 1 3-5.3.2 3-5.3.3 3-5.3.4 3-5.3.4.1 3-5.3.4.2 3-5.3.4.3 3-5.3.5 3-6 Vertical Autorotation .......................................... Forward Flight Autorotation .................................... G lide D istance ................................................. Flare .......................................................... Height-Velocity Curve ........................................... Single-engine Helicopters ....................................... M ultiengine Helicopters ........................................ MANEUVERING PERFORMANCE ................................ Power Required in Accelerated Flight .............................. Changing Energy States .......................................... Normal Acceleration Capability ................................... Effect of Wings ................................................. ENGINE(S) OFF/INOPERATIVE CONDITIONS .................... A utorotation ................................................... Performance With One Engine Inoperative (OEI) ..................... OEI Range and Endurance ....................................... Takeoff and Landing ............................................ Calculation of Flight Paths ..................................... Procedure for Calculating Takeoff and Landing Problems ............ Weight-altitude-temperature Characteristics ........................ Aircraft Trim Characteristics ..................................... LIST OF SYM BOLS ................................................ REFERENCES ................................................. Page 3-154 3-154 3-156 3-156 3-158 3-158 3-160 3-160 3-161 3-161 3-161 3-163 3-165 3-165 3-165 3-166 3-167 3-169 3-170 3-170 3-175 3-176 3-180

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CHAPTER 4 STRUCTURAL DESIGN 4-1 4-2 4-3 4-4 4-4.1 4-4.1.1 4-4.1.2 4-4.2 4-4.2.1 4-4.2.1.1 4-4.2.1.2 4-4.2.1.3 4-4.2.1.4 4-4.2.1.5 4-4.2.1.6 4-4,2.1.7 4-4.2.2 4-4.3 4-4.3.1 4-4.3.2 44.3.3 INTRODUCTION ................................................. DESIGN FLIGHT SPEEDS ......................................... GROSS W EIG HTS ................................................. FLIGHT AND TAKEOFF LOADING CONDITIONS .................. FLIGHT ENVELOPES AND MISSION PROFILES .................. Basic Flight Loading Conditions ................................... Mission Profile and Fatigue Analysis ............................... LIMIT LOAD FACTORS ......................................... Symmetrical Flight .............................................. Control of Limit Load Factors .................................. V-n Diagram ................................................. Maneuvers (Symmetrical Flight) ................................. Rotor Speed and Power Ranges ................................. Load Factors for Other Than Normal GrossWeights ............... Fatigue A nalysis .............................................. ........................................... Static Analysis .... Asymmetrical Flight ............................................ G U STS ......................................................... Conditions Requiring Gust Load Factors ............................ G ust Influence .................................................. Gust Loads During Maneuvers .................................... 4-1 4-2 4-2 4-3 4-3 4-5 4-6 4-10 4-10 4-11 4-12 4-12 4-12 4-13 4-13 4-14 4-14 4-15 4-16 4-16 4-17vii

"AMCP 706-201 TABLE OF CONTENTS (Continued) "Paragraph4-4.3.4 Page Fatigue Loadings ............................................... LANDING CONDITIONS .......................................... DESIGN LIMIT LANDING REQUIREMENTS ...................... Symmetrical Landings ........................................... Design Sinking Velocity ........................................ Landing Attitude Requirements ............................... Weight and CG Factors ........................................ Evaluation of Vehicle Designs ................................... Preliminary Substantiation Requirements .......................... Asymmetrical Landings .......................................... Landing Attitude Requirements ................................. Weight and CO Factors ................. ...................... Evaluation of Vehicle Designs ................................... RESERVE ENERGY REQUIREMENTS ............................ Reserve Energy Descent Velocities ............................... Reserve Energy Design Cotisiderations ............................. Other Considerations ............................................Autorotational Capability Indices (Landings) ........................

"4-54-5.1 4-5.1.1 4-5.1.1.1 4-5.1.1.2 4-5.1.1.3 4-5.1.1.4 4-5.1.1.5 4-5.1.2 4-5.1.2.1 4-5.1.2.2 4-5.1.2.3 S-5.2 4-5.2.1 4-5.2.2 4-5.2.34-5.2.4

4-17 4-17 4-17 4-17 4-18 4-18 4-20 4-21 4-22 4-22 4-23 4-26 4-26 4-26 4-26 4-27 4-284-28

4-5.3 4-5.3.1 4-5.3.2 4-5.3.2.1 4-5.3.2.2 4-5.3.2.3 4-5.3.2.4 4-5.3.2.5 4-5.3.2.6 4-5.3.2.7 4-5.3.3 4-5.3.4 4-6 4-6.1 4-6.1.1 4-6.1.1.1 4-6.1.1.2 4-6.1.1.3 4-6.1.1.4 4-6.1.1.5 4-6.1.2 4 4-6.1.4 4-6.1.5 4-6.2 4-6.2.1 4-6.2.2 4-6.3 4-6.3.1 4-6.3.2 4-7 viii

CRASH LOADS ................................................. Crash Environment ............................................... Structural Design ............................................... Lateral Impact ................................................ Vertical Impact .......................................... Longitudinal Impact ........................................... Combined Vertical and Forward Resultant Velocity ................. Rollover ..................................................... Landing Gear ........................................... Overhtad M asses .............................................. Seat and Restraint System Design ................................. Other Equipment and Stores ...................................... TAXI AND GROUND-HANDLING LOADING CONDITIONS ......... GROUND MANEUVERING ...................................... Braking Conditions .............................................. Two-point Braked Roll ......................................... Three-point Braked Roll ........................................ Unsymmetrical Braking ........................................ Reverse Braking .............................................. Wheel, Brakes, and Tire Heating ................................ T urning ....................................................... Pivoting ................................................ Taxiing ........................................................ Special Tail-gear Conditions ...................................... JACKING AND MOORING CONDITIONS ......................... lacking Loads .................................................. M ooring Loads ................................................. TOWING AND TRANSPORT LOADS ............................. Towing Loads .................................................. Transport Loads ................................................ MISCELLANEOUS LOADING CONDITIONS ........................

4-28 4-29 4-29 4-31 4-31 4-31 4-31 4-31 4-32 4-32 4-32 4-32 4-33 4-33 4-33 4-33 4-33 4-33 4-33 4-33 4-33 4-34 4-34 4-35 4-35 4-35 4-35 4-35 4-36 4-36

2 .. . '

..

~~~~~~. .,......... .::

AMCP 706-201

C'TABLEParagraph 4-7.1 4-7.1.1 4-7.1.2 4-7.1.3 4-7.2 4.8 4-8.1 4-8.1.1 4-8.1.1.1 4-8.1.1.2 4-8.1.1,3 4-8.1.1.4 4-8.1.1.5 4-8.1.1.6 4-8.1.1.7 4-8.1.1.8 4-8.1.2 4-8.1.3 4-8.1.4 4-8.2 4-8.2.1 4-8.2.2 4-8.2.2.1 i 4 8.2.2.2 4-8.2.2.3 4-8.2.2.4 4-8.2.3 4-8.3 4-8.3.1 4-8.3.2 4-8.3.3 4-8.3.4 4-8.4 4-8.4.1 4-8.4.1.1 4-8.4.1.2 4-8.4.1.3 4-8.4.1.4 4-8.4.2 4-8.4.3 4-8.4.4 4-8.4.4.1 4-8.4.4.2 4-8.4.4.3 4-8.5

OF CONTENTS (Continued)Page

S4-8.5.1i.

4-8.5.1.1 4-8.5.1.2 4-8.5.1.3

ROTOR ACCELERATION ........................................ Determination of Ground Idle Rotor Speed ......................... Determination of Peak Engine Torque .............................. Rotor Blade Loads .............................................. ROTOR BRAKING LOADS ....................................... SPECIAL LOADING CONDITIONS ................................. HARD-POINT LOADS ........................................... External Store Installations ....................................... D esign Criteria ............................................... W eight ..................................................... Center of G ravity ............................................. Methods of Analysis .......................................... Extent of Substantiation ........................................ Aerodynamic Load Determination ............................... D ynam ic Loads ............................................... Flight Load Determination ..................................... Reaction Forces ................................................ Firing Frequency Dynamics ...................................... Blast Overpressures ............................................. EXTERNAL CARGO ............................................ Rigidly Attached External Cargo .................................. Sling-loaded External Cargo ...................................... Static Loads .................................................. Aerodynam ic Loads ........................................... Com bined Loads .............................................. Asym m etrical Loading ......................................... Lifting and Aerial Towing ........................................ FLOORING AND WORK PLATFORMS ........................... Flooring Design Criteria ......................................... W ork Platform Design Criteria .................................... Interchangeability and Replacea .ility ............................... D urability . ................................ ................... DOORS AND HATCHES ......................................... D esign C riteria ................................................. Concentrated Loads ........................................... D istributed Loads ............................................. D eflection C riteria ............................................. Production Tolerance ......................... ................ Removal and Replacement ....................................... Emergency Jettison and/or Personnel Egress ........................ Size of O penings ................................................ A ccess O penings .............................................. Entry O penings ............................................... Egress O penings. ..................................... ........ STEPS AND HANDHOILDS ....................................... Steps .......................................................... Size and Clearance Requirements ................................ Strength Requirem ents ............. ........................... Other Considerations . ..................... ....................

4-36 4.36 4-38 4-39 4-39 4.39 4-39 4-39 4-39 4.40 4,40 . 40 4-40 4-40 4-40 4-41 4-41 4-41 4-42 4-42 4-42 4-43 4-4o 4-43 4-43 4-43 4-43 4-44 4-44 4-45 4.45 4-45 4-45 4-45 4-46 4-46 4-47 4-47 4-47 4-47 4-47 4-47 4-47 4-48 4-48 4-48 4-48 4-48 4-49 ix

AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph Handholds .................................................. Size and Clearance Requirements for Handholds.................... Strength Requirements ....................................... "4-.5.2.2 Other Considerations ........................................ 4-8.5.2.3 STRUCTURAL. SUBSTANTIATION, ROTOR, DRIVE AND CONTROL 4-9 SYSTEMS..................................................... ROTOR LOADS-STEADY AND UNSTEADY ...................... 4-9.1 Airloads.................................................... 4-9.1.1 Impressed Blade Pitch........................................ 4-9.1.1.1 Airflow ................................................... 4-9.1.1.2 Rotor Position and Motion .................................... 4-9.1.1.3 Airfoil Characteristics........................................ 4-9.1.1.4 491.5Transient Loads............................................. Analytic Approach to Rotor Load Prediction ........................ 4-9.1.2 Preliminary Design Considerations ................................ 4-9.1.3 HUB LOADS ................................................. 4-9.2 Characteristics of Rotor Hubs.................................... 4-9.2.1 Analysis of Rotor Loads........................................ 4-9.2.2 Flapwise Loads............................................. Inplane Loads.............................................. 4-9.2.2.2 Design Loads for Fatigue....................................... 4-9.2.3 Endurance Load Level ....................................... 4-9.2.3.1 .......................... Maneuver Loads ................. 4-9.2.3.2 Ground-air Load Cycle....................................... 4-9.2.3.3 Miscellaneous Loading Conditions ................................ 4-9.2.4 Starting and Shutdown Loads .................................. 4-9.2.4.1 Wind Loads ............................................... 4-9.2.4.2 Stop-banging Loads.......................................... 4-9.2.4.3 Folding Loads.............................................. 4-9.2.4.4 Mooring and Tiedown Loads................................... 4-9.2.4.5 Hoisting Loads............................................. 4-9.2.4.6 MECHANICAL DRIVE SYSTEM LOADS .......................... 4-9.3 Load Spectra ................................................ 4-9.3.1 ....... Cubic Mean Load ..................................... 4-9.3.2 Steady Loads ................................................ 4-9.3.3 Fatigue Loads................................................ 4-9.3.4 Load Analysis for Typical Helicopter .............................. 4-9.3.5 Main and Tail Rotor Gearboxes ................................ 4-9.3.5.1 Free-wheeling Unit .......................................... 4-9.3.5.2 Main Transmission Bevel Gear Stages............................ 4-9.3.5.3 Planetary Gear Stages ........................................ 4-9.3.5.4 Spur and Helical Gear Systems ................................. 4-9.3.5.5 Main Housing Loads......................................... 4-9.3.5.6 Drive Shaft and Coupling Loads ................................ 4-9.3.5.7 CONTROL SYSTEM SUBSTANTIATION........................... 4-9.4 Control System Description...................................... 4-9.4.1 Description of Load Sources and Reactions.......................... 4-9.4.2 Trim Actuators............................................. 4-9.4.2.1 Rate Restrictors............................................. 4-9.4.2.2 4-8.5.2 4-8.5.2.1 Page 4-48 4-48 4-48 4-49 4-49 4-49 4-49 4-49 4-50 4-52 4-52 4-56 4-57 4-59 4-62 4-62 4-62 4-63 4-63 4-64 4-64 4-64 4-64 4-64 4-64 4-65 4-65 4-65 4-65 4-65 4-65 4-66 4-66 4-68 4-68 4-68 4-69 4-70 4-71 4-72 4-73 4-74 4-74 4-75 4-76 4-77 4-79 4-79

V4-9.2.2.1

)

X

.

"AMCP 706-201TABLE OF CONTENTS (Continued)Paragraph 4-9.4,2.3 4.9.4.2.4 4-9.4.2.5 Hydraulic Boost .............................................. Power Systems ................................................ Stability Augmentation ......................................... Page 4-80 4-80 4-81

'

4-9.412.64-9.4.2.7 4-9.4.3 4-9.4.4 4-9.4.5 4-9.4,6 4-9.4.7 4-9.4.7.1 4-9.4.7.1.1 4-9.4.7.1.2 4-9.4.7.1.3 4.9.4.7.1.4 4-9.4.7.2 4-9.4.7.2.1 4-9.4.7.2.2 4-9.4.7.2.3 4-9.4.7.3

Vibration Absorbers

................................

......

.....

4-814-81 4-81 4-84 4-84 4-84 4-85 4-86 4-86 4-86 4-87 4-87 4-87 4-87 4-88 4-89 4-89

System Stops ................................................. Determination of Loads .......................................... Ground Condition Load Criteria .................................. M iscellaneous Controls ........................................... System Failure Effects ........................................... Control System Substantiation ..................................... Lower Controls ............................................... Static Design Load ............................................ A nalysii ..................................................... M aterial Allowables ........................................... .............................. M argin of Safety ............... Rotating and Stationary Upper Controls .......................... Alternating Design Loads ....................................... Static Strength ................................................ Stiffness Requirements ......................................... Structural Concepts ............................................

4-104-10.1 4-10.1.1 4-10.1.2 4-10.1.2,1

AIRFRAME STRUCTURAL SUBSTANTIATION

.....................

4-904-90 4-90 4-91 4-91

FUSELAGE STRUCTURE ........................................ Fuselage System Description ...................................... Load Sources ................................................... Flight M aneuver Loads ........................................

4-10.1.2.24-10.1.2.3 4-10.1.2.4 4-10.1.2.5 4-10.1.2.64-10.1.3

G ust Loads

..................................................

4-934-93 4-94 4-95 4-964-96

Landing Loads ................................................ Crash Loads ................................................. O ther Loadings ............................................... Load Paths ...................................................Determination of Loads ..........................................

I1

4.10.1.3.1

Weight Distribution ...........................................

4-96

4-10.1.3.24-10.1.3.3 4-10.1.3.4 4-10.1.4 4-10.1.5 4-10.1.6 4-10.1.7 4-10.1.8 4-10.2 4-10.2.1 4-10.2.2 4-10.2.3 4-10.2.4 4-10.2.5 4-10.2.6 4-10.2.7 4-10.2.8

Unit Shear, Moment, and Torsion Distribution .....................Specific Maneuver and Landing Condition Load Curves .............. Critical Condition Selection and Superposition of System Loads ....... Fail-safe Aspects ............................................... Fatigue Considerations ........................................... Internal Loads .................................................. Prelim inary Sizing .............................................. Substantiation .................................................. WING AND EMPENNAGE SUBSTANTIATION .................... Basic Considerations ............................................. Sign Convention ................................................ Inertial Loads .................................................. Aerodynamic Load Distribution ................................... G ust Loading .................................................. G round-handling Loads .......................................... Mooring, Jacking, Hoist, and Sling Loads ........................... Structural Design Requirements ...................................

4-964-98 4-98 4-100 4-100 4-101 4-102 4-102 4-102 4-103 4-104 4-104 4-106 4-108 4-109 4-109 4-109

r

4

,

xi

I)

AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph Page Combined Loading Conditions .................................... Stress A nalysis ................................................. LANDING GEAR SUBSTANTIATION ............................. Load Factor Determination ....................................... Specific Landing Gear Load Determination ......................... Wheel Gear Loads ............................................ Skid Gear Loads .............................................. Float G ear Loads ............................................. Reserve Energy Loads ........................................... Preliminary Structural Sizing ..................................... Substantiation of Landing Gear Design ............................. SUBSTANTIATION OF MISSION EQUIPMENT INSTALLATIONS ... Equipm ent Loads ............................................... Equipment Types. ............................................ Cabin Equipm ent ............................................. Equipment Outside Cabin but Inside Helicopter .................... Externally Installed Equipment .................................. Load Types .................................................. Flight M aneuver Loads ........................................ . . Air Loads ................................................. Vibratory Loads ...... ....................................... Determination of Loads ........................................ Loads on Cabin Equipment ..................................... Loads For Equipment Installed Internally but Outside of Cabin ....... Loads on Externally Attached Equipment ........................ Load Paths .................................................... Other Considerations ............................................ Prelim inary Sizing .............................................. Substantiation .................................................. FATIGUE LIFE DETERMINATION ................................. G ENERAL ..................................................... FATIGUE-CRITICAL COMPONENTS ............................. FATIGUE LOADINGS ........................................... Determination of Composite Maneuver Spectrum ..................... Determination of Gross Weight and Rotor Speed Distributions ......... FATIGUE PROPERTIES ......................................... FA T IG U E LIFE ................................................. SERVICE LIFE CALCULATION .................................. SPECTRUM TESTING ........................................... INFINITE FATIGUE LIFE ....................................... LIST O F SY M BO LS ................................................ REFERENCES ................................................ 4.111 4-112 4-112 4-112 4-115 4-115 4-115 4.118 4-118 4.118 4-119 4-119 4-119 4-119 4-119 4-120 4-120 4-120 4-120 4-120 4-121 4-121 4-121 4-122 4-122 4-123 4-124 4-125 4-125 4-125 4-125 4-125 4-126 4-126 4-128 4-132 4-133 4-135 4-136 4-137 4-137 4.140

4-10.2.94-10.2.10 4-10.3 4-10.3.1 4-10.3.2 4-10.3.2.1 4-10.3.2.2 4-10.3.2.3 4-10.3.3 4-10.3.4 4-10.3.5 4-10.4 4-10.4.1 4-10.4.1.1 4-10.4.1.1.1 4-10.4.1.1.2 4-10.4.1.1.3 4-10.4.1.2 4-10.4.1.2.1 4-10.4.1.2.2 4-10.4.1.2.3 4-10.4.1.3 4-10.4.1.3.1 4-10.4.1.3.2 4-10.4.1.3.3 4-10.4.2 4-10.4.3 4-10.4.4 4-10.4.5 4-11 4-11.1 4-11.2 4-11.3 4-11.3.1 4-11.3.2 4-11.4 4-11.5 4-11.6 4-11.7 4-11.8 4-12

CHAPTER 5 DYNAMICS 5-1 5.2xii

IN TRO DU CT IO N

................................................. .........................

5-1 5-3

AIRFRAME DYNAMICS AND VIBRATION

AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph5-2.1 5-2.2 5-2.2.1 5-2.2.2 5-2.2.3 5-2.2.4 5-2.2.4.1 5-2.2.4.2 5-2.2.4.3 5-2.2.4.4 5-2.3 5-2.3.1 5-2.3.2 5-2.3.3 5-2.3.3.1 5-2.3.3.2 5-2 3.3.3 5-2.45-2.4.1

PageG EN ERA L ...................................................... 5-3 VIBRATION CONTROL ANALYSIS AND DESIGN TECHNIQUES ... 5-4 Vibration A nalysis .............................................. 5-5 Equations of M otion ............................................. 5-5 Normal Mode Solution ........................................... 5-6 Methods of Calculating Normal Modes and Natural Frequencies ....... 5-7 Stodola Method and Matrix Iteration ............................. 5-8 M yklestad M ethod ............................................ 5-8 Finite Element Analysis ........................................ 5-8 Other M ethods ............................................... 5-9 VIBRATION REDUCTION ....................................... 5-9 Airframe M odification ........................................... 5-9 Vibration Absorbers ............................................. 5-9 Vibration Isolation .............................................. 5-10 Mathematical M ethods ......................................... 5-10 Recent Developments .......................................... 5-111 Fail-safe Design ............................................... 5-12 EXCITATION SOURCES ......................................... 5-13 R otor Forces ................................................... 5-13 O ther Sources .................................................. 5-14 GROUND RESONANCE ......................................... 5-15 Description of the Phenomenon ................................... 5-15 Im portant Parameters .. ......................................... 5-16 M ethod of A nalysis ............................................. 5-16 DESIGN CRITERIA AND CONSIDERATIONS ..................... 5-17 ROTOR SYSTEM INSTABILITIES .................................. 5-17 G EN ER A L ...................................................... 5-17 SINGLE-BLADE INSTABILITY ANALYSES ....................... .5-19 Single-blade Flutter and Torsional Divergence ....................... 5-19 Single-blade Flapping Instability ................................... 5-2.1 Single-blade Coupled Pitch-flap-lag Instability ....................... 5-25 COUPLED ROTOR/AIRFRAME INSTABILITY ANALYSES ......... 5-26 M ultiblade Flutter .............................................. 5-27 M ultiblade Flapping Instability .................................... 5-27 A xial F low ................................................... 5-27 Oblique Flow . ................................................ 5-29 Coupled Rotor-Airframe Lead-lag Instability ......................... 5-30 EFFECT OF ROTOR CONFIGURATION ON INSTABILITIES ....... 5-32 Fully H inged R otor ............................................. 5-33 Semihinged Rotor ............. ................................. 5-33 Seesaw R otor ................................................... 5-13 Floating H ub Rotor ................... ....................... . . 5-33 H ingeless R otor ................................................ 5-34 SUBSTANTIATION CRITERIA AND METHODS ................... 5-34 LIFTING SURFACE DYNAMICS ................................... 5-36 G E N ER A L ...................................................... 5-36 Definition% .............................. ..... . ................ 5-36 Basis of C riteria ................................................ 5-36 FLU TT E R ...................................................... 5-375-4.2I

)-

5-2.4.2 5-2.5 5-2.5.1 5-2.5.2 5-2.5.3 5-2.6 5-3 5-3.1 5-3.2 5-3.2.1 5-3.2.2 5-3.2.3 5-3.3 5-3.3.1 5-3.3.2 5-3.3.2.1 5-3.3.2.2 5-3.3.3 5-3.4 5-3.4.1 5-3.4.2 5-3.4.3 5-3.4.4 5-3.4.5 5-3.5 5-4 5-4.1 5-4.1.1 5-4.1.2 54.2

71

1)

.~ ,

,.l7"t"AW

W~~

~

AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph 5.4.3 5.4.4 DIVERGENCE ..................................................

-)Past 5.37

54.4.1 5-4.4.2 5-4.4.2.1 5.4.4.2.2 54.5 5-5 5.5.1 5.5.2 5-5.3 5.5.3.1 5-5.3.2 5-5.3.3 5-5.3.3.1 5-5.3.3.2 5-5.3.3.3 5-5.3.4 5.5.3.5 5-6

CONTROL SURFACE BALANCE AND STIFFNESS CRITERIA Mass Balance of Control Surface ................................. Balance W eights ............................................... . Location of Balance Weights .................................... Rigidity and Strength of Balance Weight Attachments ............... PROPELLER-NACELLE WHIRL FLUTTER ........................ DRIVE SYSTEM DYNAMICS ....................................... SCO PE .......................................................... DESIGN PHILOSOPHY AND DESIGN CRITERIA .................. MATHEMATICAL METHODS .................................... The Mathematical Model ......................................... Solution by Matrix Methods ...................................... Porter's M ethod ................................................ Mode Shapes Calculated by Porter's Method ...................... Parametric Studies ............................................ Sample Calculations ........................................... Effect of Rotor Characteristics .................................... Compatibility Between the Drive System and the Engine and Engine Control System ....................................................... LIST OF SYMBOLS ................................................ REFERENCES ................................................

5-38 5.38 5.38 5.38 5-38 5-38 5-39 5-39 5-39 5-40 5-40 5.40 5-41 5-42 5-42 543 5-46 5-46 5-48 5.50

CHAPTER 6 STABILITY AND CONTROL 6-1 6-2 6-2.1 6-2.1.1 6-2.1.2 6-2.1.3 6-2.1.4 6-2.1.5 6-2.2 6-2.3 6-2.4 6-2.4.1 6-2.4.2 6-2.4.3 6-2.2 '.3.1 6-2.4.3.2 6-2.4.4 6-2.4.4.1 6-2.4.4.2 6-2.4.4.3 xiv INTRODUCTION ................................................. FUNDAMENTALS OF HELICOPTER STABILITY AND CONTROL .... DEFINITIONS .................................................. Axis Systems .................................................. . G raivity Axes ................................................... Stability Axes ................................................. . Body A xes ..................................................... Choice of Axes ................................................ . EQUATIONS OF MOTION ....................................... STABILITY DERIVATIVES ....................................... BASIC STABILITY AND STABILIZATION SYSTEMS ............... Pertinent Rotor Derivatives ....................................... Dynamic Stability of Basic Helicopter .............................. Fundamentals of Automatic Stabilization ........................... Control Input Required ........................................ Response Char-cteristics of Mechanical Gyratory Systems ........... Gust Alleviation ................................................ Rotor Sensitivity .............................................. Mechanical Feedback Systems ................................... Electronic Feedback Systems .................................... 6-1 6-1 6.1 6-1 6-2 6-2 6-2 6-2 6-3 6-5 6-6 6-7 6-9 6-11 6-Il 6-14 6-16 6-16 6-18 6-19

*

"Ii4

AMCP 706-201

)Paragraph 6-2.5 6-2.5.1 6-2.5.1.1 6-2.5.1.2 6-2.5.2 6-2.5.3 6-2.5.4 6-3 6-3.1 6-3.1.1 6-3.1.1.1 6.3.1.1.2 6-3.1.1.3 6-3.1.1.4 6-3.1.2 6-3.1.2.1 6-3.1.2.1.1 6-3.1.2.1.2 6-3.1.2.2 6-3.1.2.2.1 6-3,1.2.2.2 6-3.2 6-3.2.1 6-3.2.2 6-3.2.2.1 6-3.2.2.2 6-3.2.2.3 6-3.2.3 6-3.2.3.1 6-3.2.3.2 6-3.1 6.3.5 6-3.5. I 6-3.5.2 6-3.5.3 6-3.5.4 6-3.5.5 6-3.5.6 6-3.5.7 6-3.5.7.1 6-3.5.7.2 6-3.5.7.3 6-3.5.8 6-3.6 6-3.6.1 6-3.6.1.1 6-3.6.1.2

TABLE OF CONTENTS (Continued)Page SPECIAL MISSION CONSIDERATIONS ........................... Center of' Gravity Travel ....................................... Single-rotor Helicopters ........................................ Tandem-rotor Helicopters ...................................... Hover Height Control ............................ .............. Weapon Platform Requirements . ................................... VFR /IFR Flight ................................................ FLIGHT DYNAM ICS .............................................. CONTROL POWER .............................................. R equirem ents ............................... ................... Control Sensitivity and Damping Requirements .................... Control Sensitivity and Damping Considerations ................... Control Power Requirements .................................... Other Control Power Considerations ............................. Determination of Control Characteristics ............................ Pitch and R oll ............................. .................. Single-rotor Helicopters ........................................ Tandem-rotor Helicopters ................................... Y aw ........................................................ Single-rotor Helicopters ......................................... Tandem-rotor Helicopters ...................................... CONTROL. POSITION VERSUS SPEED ............................ Requirem ents ................................................... Physical Phenomena Involved ..................................... Single-rotor Helicopters ...................................... Tandem-rotor Helicopters .................................... Synchropters ................................................. Methods for Calculating Speed Stability ............................ Single-rotor Helicopters ........................................ Tandem-rotor Helicopters ...................................... DYNAM IC STABILITY .......................................... EFFECTS OF EXTERNAL STORES ............................... A ngle of A ttack ................................................ A ttitude ....................................................... Aerodynamic Forces and Jettisoning of Stores or Dispensing of Payloads . Forced Jettisons ................................................ Effects of External Stores on Static and Dynamic Stability (Laterally Symmetrical Loadings) ................................................ Effects of External Stores (Asymmetrical Loadings) ................... Effects of W eapon Recoil ......................................... High-rate-of-fire W eapons ...................................... Medium- and Low-rate-of-fire Weapons ........................... High-impulse, Single-shot Weapons .............................. Sling Loads .................................................... CONTROL SYSTEMS ............................................ Control Feel ................................................... Force Feel ................................................... Control Forces ............................................... 6-20

6-21. 6-21 6-23 6.24 6-26 6-27 6-28 6-28 6-29 6-29 6-32 6-34 6-34 6-35 6-35 6-35 6-38 6-38 6-38 6-39 6-39 6-39 6-40 6-40 6-41 6-4 1 6-41 6-41 6-45

:1

[

SPEED STABILITY AND MANEUVERING FLIGHT

...............

6-46

6-47 6-48 6-48 6-4 6-51 6-51 6-52 6-52 6-52 6-53 6-53 6-54 6-54 6-54 6-54 6-54 6-56 xv

0:,

AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph 6-3.6.1.3 6-3.6.2 6-3.6.3 6-4 6-4.1 64.2 6-4.2.1 6.4.2.2 6-4.2.3 6-4.2.4 6-4.2.5 6-4.2.6 6-4.3 6-4.3.1 6-4 ,3.2 6-4.3.3 6-4.3.4 6-4.3.5 6-4.3.6 6.4.4 6-4.4.1 6-4.4.1.1 6-4.4.1.2 6-4.4.1.3 6-4.4.1.3.1 6-4.4.1.3.2 6-4.4.1.3.3 6-4.4.1.4 6-4.4.1.5 6-4.4.1.6 6-4.4.2 6-4.4.2.1 6-4.4.2.2 6-4.4.2.3 6-4.4.2.4 6-4.4.2.5 6-4.4.3 6-4.4.3.1 6-4.4.3.2 6-5 Control Linkage..............................................6-58 Control Harmony ............................................... Trim System s .................................................. STABILITY AUGMENTATION ..................................... STABILITY REQUIREMENTS .................................... STABILITY AUGMENTATION SYSTEMS (SAS) .................... Pitch Control .................................................. Normal Acceleration Control ..................................... Long-period M ode .............................................. Hardware ...................................................... G ust A lleviation ................................................ Dynamic Instability ............................................. STABILITY AUGMENTATION SYSTEM FAILURE ANALYSIS ...... Passive Failures ................................................. Hardover Failures ............................................... N ull-oft.,et Failures .............................................. SAS M onitoring ................................................ Redundancy .................................................... Other Considerations ............................................ AUTOMATIC STABILIZATION EQUIPMENT ...................... Pilot-assist M odes . .............................................. A ttitude-H old ................................................ Heading-Hold/Select Mode ..................................... Control Stick M aneuvering ..................................... Disconnect M aneuvering ....................................... Position Proportioral Maneuvering ... ............................ Force Proportional Maneuvering ................................. Automatic Turn Coordination ................................... Altitude-hold and Altitude-select ................................. Velocity Vector Control ........................................ Goidance Modes .................. ........................ Automatic Navigation .......................................... A utom atic Transition .......................................... A utom atic Hover ............................................. Autom atic Stationkeeping ....................................... Automatic Terrain-folloving ... ................................. Automatic Stabilization Equipment Failures ......................... Passive Failures ....... ....................................... H ardo,,er Failures ............................................. LIST O F SY M BO t.S .............. ................................. REFERENCES ............ .................................... Page

6-58 6-60 6-60

6-60

6-62 6-62 6-65 6-66 6-67 6-67 6-71 6-73 6-73 6-73 6-74 6-74 6-74 6-75 6-75 6-75 6-75 6-76 6-77 6-77 6-77 6-78 6-78 6-79 6-80 6-81 6-81 6-83 6-83 1-84 6-84 6-85 6-85 6-85 6-86 . 6-88

;,

)

CHAPTER 7 DRIVE SYSTEM DESIGN 7-1 7-1.1 7-1.1.1 xvi IN T RO D UCT IO N ................................................. TRANSM ISSION SYSTEMS ....................................... G ears . .... ......... ............ ... .... ......... 7-1 7-1 7-2

... ... ....

.....

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,

S

AMCP 706-201i ii

TABLE OF CONTENTS (Continued)Paragraph7-1.1.2 C lutches .......................................................

JPage7-2

7-I. 1.3 7-1.1.47-1.1.5

Transmission Shafting ........................................... Bearings and Housings ...........................................Lubrication...............

7.2 7-3..................... 7..3.

t................

7-1.1.6 7-1.27-2

A ccessories .................................................... ROTOR BRAKES ...............................................SYSTEM SELECTION ..............................................

7-4 7-47-5

J

7-2.1 7-2.2 7-2.2.1 7-2.2.? 7-2.2.3 7-2.2.4 7-2.2.5 7-3 7-3.1 7-3.1.1 7-3.1.1.. 7-3.1.1.2 7-3.1.1.3 7-3.1.1.4 7-3.1.2 7-3.2 7-. 2. i 7-3.2.1.1 7-3.2.1.2 7-3.2.2 7-3.2.2.1 7-3.2.2.2 7-3.2.3

GENERAL .............................. ....................... BASIC GEARED TRANSMISSION TYPES ......................... Spur G ears .............................................. H elical G ears ................................................... Bevel G ears .................................................... Planetary Gearing ............................................. M i.,celaneous Types of Gearing ............. ..................... TRANSMISSION REQUIREMENTS ................................. GEAR SYSTEMS ................................................ Design Considerations ........................................... Life-load Relationship .......................................... Suggestions for Good Design Practice of Gearboxes ................. Gearbox Lubrication Considerations .............................. Recess Action G ears ........................................... Preliminary Gearbox Weight Considerations .......................... BEA R IN G S .......... .......................................... Typical Installations ............ ................................ Accessory Bearings ............................................ Plate Thrust Bearings .......................................... Special Purpose Bearings ......................................... Transmission M ain Drive Train ................................. Oscillating or Limited Motion Bearings ........................... M ountings .....................................................

....

7-5 7-5 7-5 7-7 7-7 7.11 7-12 7-14 7-14 7-17 7-22 7-23 7-23 7-24 7-24 7-24 7-25 7-25 7-26 7-26 7-26 7-31 7-3 1

A

,

7-3.2.47 3.2.4.1 7-3.2.4.2 7-3.2.5 7-3.2.5.1 7-3.2.5.2 7-3.2.6 7-3.2.7 7-3.3 7-.1.3.1 " 7-3.3.1.1 7-3.3.1.2 7-3.3.1.3 7-3.3.2 7 .3.3 7-3.47-3.4.1

Seals . . .. .. . .. . .. .. .. . . ... . .. .. . .. . .. . .. . .. ... . ... . .. . .. .. . ... .

7-3 3

.

Integral T ype ...... .......................................... 7-33 Separate T%pe ................................................ 7-35 Installation Consideration ........................................ 7-37 I.ubrication ................................................... 7-37 Inner and Outer Ring Shaft and HIousing Fits ..................... 7-3. Common Problems in Bearing and Support Application ............... 7-38 F-atigue Considerations ........................................... 7-3t) LU BR IC A T IO N ............ .................... ...... ......... 7.39 .... . . . V';! ................. L~ubrication System . ...................... Splash l~uhrication Svytem ...................................... 7-31 Circulating Lubrication Systems .................................. . 7-39 L ubricatin!, O il ............................................... 7-40 luhrication System Components and Arrangement ................... 7-40 Oil Flow Requirements .......................................... 7-41 -EAT REJ[-'.CTION AND TRANSMISSION EFFICIENCY . ........... 7-41Gear and Bearing l.oscs ......................................... 7-42

7-3.4.1.1 7-3.4.1.2

Preliminary Gear and Bearing !.o,,, Predictions .................... (icar and Wearing I.os, Calculation s ..............................

7-42 7-43x% ii

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7I

T

AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph 7-3.4.2 7.3.4.3 7-4 Windage and Churning Losses .................................... Conversion of Losses to Heat Loss and Efficiency .................... TRANSMISSION DESIGN .......................................... MAIN ROTOR TRANSMISSION .................................. ANTITORQUE ROTOR TRANSMISSION .......................... COMBINING TRANSMISSION ................................... Functions ............... ...................................... Typical Combining Transmissions ................................. ENGINE/ROTOR CROSS-SHAFTING ............................. Functions and Features ......................................... Shafting ....................................................... Couplings ...................................................... ACCESSORY DRIVES ............................................ Helicopter Accessories ........................................... Accessory Drive Arrangement . ................................... Accessory Drive Pads ........................................... Specifications ................................................... State-of-the-Art ................................................. FAILURE WARNING SYSTEMS .................................. SH A FTS .......................................................... SHAFT DESIGN ................................................. Design Parameters .............................................. Strength/W eight .............................................. Dynamic Considerations ........................................ Shaft End Configurations ....................................... Vulnerability ................................... Large- vs Small-diameter Shafts ................................... SHAFT DYNAMICS ............................................. Critical Speeds ................................................. M athematical M ethods ......................................... Nonuniform Shafts ............................................ Uniform Shafts .............................................. Effects of Elasticity and Restraints at Bearings ..................... Effects of Masses Concentrated Between Bearings .................. Gyroscopic Effects ............................................ Other Effects ................................................. Design Criteria ................................................. CLUTCHES, BRAKES, AND COUPLINGS ........................... CLUTCH ES ..................................................... Sprag Theory ................................................... Sprag Clutch Design ............................................. Torque Capacity ............... ............................. ......... Inner Race Hertz Stress ............................ Overrunning Clutch Races ...................................... Positive Continuous Engagement Sprag ............................ Overrunning Capability and Lubrication ............................ Roller Clutch .................................................. SPLIN ES ........................................................ Types of Splines ................................................ Page 7-43 7-44 7.44 7-44 7-46 7-51 7-51 7-52 7-52 7.53 7-53 7-54 7-55 7-55 7-55 7.56 7-57 7-57 7-57 7-59 7-59 7-59 7-59 7-61 7-61 7.61 7-62 7-67 7-62 7-63 7-63 7-64 7-65 7-67 7-67 7-68 7-69 7-69 7-69 7-69 7-71 7-71 7-71 7-72 7-74 7-75 7-77 7-77 7-78

( .9

7.4.17.4.2

7-4.37-4.3.1 7-4.3.2 7-4.4 7-4.4.1 7-4 .4.2 7-4 .4.3 7-4.5 7-4.5.1 7-4.5.2 7-4.5.3 7-4.5.4 7-4.5.5 7-4.6 7-5 7-5.1 7-5.1.1 7-5.1 .1.1 7-5.1.1.2 7-5.1.1.3 7-5.1.2 7-5.1.3 7-S.2 7-5.2.1 7-5.2.1.1 7-5.2.1.1.1 7-5.2.1.1.2 7-5.2.1.1.3 7-5.2.1.1.4 7-5.2.1.1.5 7-5.2.1.2 7-5.2.2 7-6 7-6.1 7-6.1.1 7-6.1.2 7-6.1.2.1 7-6.1.2.1.1 7-6.1.2.1.2 7-6.1.3 7-6.1.4 7-6.1.5 7-6.2 7-6.2.1 xviii

.

2

S

AMCP 706-201

)yParagraph 7-6.2.2 7.6.2.3 7.6.2.4 7-6.2.5 7.6.2,6 7-6.3 7-6.3.1 7-6,3.2 7-6.3.3 7-6.3.4 7-6.3.5 7-6.3.6 7-6.4 7-6,4.1 7-6.4.2 7-6.4.3 '.6.4.4

TABLE OF CONTENTS (Continued)Page Typical A pplic'itions ............................................. Design Consideratl'ns ........................................... Spline Capacity (SAE Type) ...................................... Materials, Metallurgy, and Lubrication .............................. Failure Modes ................................................. MECHANICAL COUPLINGS ..................................... Laminated Ring Couplings ....................................... Flexible D isk Couplings .......................................... G ear C ouplings ................................ ................ Universal Joints ................................................ Elastom eric Couplings .... ....................................... Shaft Installation ............................................... ROTO R BRA K ES ................................................ Need for Rotor Brakes ........................................... Full On/Off vs Controllable Systems ............................... Description of a Typical Simple System ......... ................... Predesign Sizing Considerations ................................... Service Experiences .............................................. ISOLATION SYSTEM S ............................................. LIST O F SYM BO LS ................................................ REFERENCES ................................................ 7.78 7-78 7.79 7-80 7--0 7-81 7.82 7-83 7-84 7.84 7-,4 7-85 7-85 7-85 7-86 7-86 7-87 7-87 7-87 7-88 7.90

.

"7-6.4.57.7 7-8

CHAPTER 8 POWER PLANT SELECTION AND INSTALLATION 8-1 8-1.1 8-1.2 8-1.3 8-1.4 8-1.5 8-1.6 8-1.7 8-1.8 8-1.9 8-1.10 8-1.11 A-2 8-2.1 8-2.1.1 8-2.1.2 8-2.1.3 8-2.1.4 8-2.2 8-2.2.1 8-2.2.2 8-2.2.3 8-2.2.4 INTRO DUCTION ................................................. SELECTIO N .................................................... ENGINE POWER OUTPUT SHAFT ................................ ENGINE REPLACEMENT .............. ......................... ENGINE AIR INDUCTION SYSTEM .............................. ENGINE STARTING SYSTEM .................................... LUBRICATION, COOLING, AND EXHAUST SYSTEMS ............. FUEL SYSTEM .................................................. %ECONDARY POWER SYSTEM .................................. POWER MANAGEMENT SYSTEM ................................ AUXILIARY POWER UNIT (APU) ................................ SAFETY REQUIREMENTS ....................................... ENGINE INSTALLATION CONSIDERATIONS ...................... ENGINE MOUNTING AND VIBRATION ISOLATION .............. Engine Mounting Considerations .................................. Engine Mounting Forces and Reactions ............................. Engine Vibration Isolation ........................................ Engine Mount Installation Considerations ........................... ENGINE AIR INDUCTION SYSTEM .............................. G eneral Design ................................................. Air Induction System Inlet Location ............................... Engine Air Induction System Pressure Losses ........................ Evaluation of Pressure Losses ..................................... 8-1 8-1 8-1 8-1 8-2 8-2 8-2 8-2 8-2 8-3 8-3 8-3 8-4 8-4 84 8-4 8-4 8-5 8-5 8-5 8-6 8-6 8-7 xix

AMCP 706-201

TABLE OF CONTENTS (Coatimnced)Paragraph 8-2.2.5 8-2,2.6 8-2.2.6.1 8-2.2.6.2 8-2.2.6.3 8-2.2.6.4 8-2.2.7 8-2.2.8 8-2.3 8-2.3.1 8-2.3.2 8-2.3.3 8-2.3.4 8-2.3.5 8-2.4 8-2.4.1 8-2.4.2 8-2.4.4 8-2.4.5 8-2.4.6 8-2.4.7 8-2.4.8 8-2.4.9 Foreign Object Damage (FOD) .................................... Engine Air Particle Separator (EAPS) .............................. Inertial Separators ............................................. Vortex Tube Ineitial Separators ................................. Centrifugal (Inertial) Separator ........ ...................... EAPS Scavenge Pump ......................................... Power Losses ................................................... Air Induction System Anti-icing Provisions ......................... EXHAUST SUBSYSTEM .......................................... Exhaust Wake .................................................. Engine Exhaust Noise ........................................... Performance Losses ............................................. Infrared Radiation Suppression .................................... Estimation of Exhaust IR Emissions ............................... PROPULSION SYSTEM COOLING ................................ Insulation .................................................... Heat Exchangers . ............................................... Fans .......................................................... Engine Compartment Cooling...................................... Cooling System Air Inlet ......................................... Ejectors ...................................................... Survivability Upon Loss of Cooling System .......................... Cooling Power Requirements ..................................... ACCESSOR IES .................................................. Bleed-air-driven Accessories ...................................... Mechanically Driven Accessories .................................. Mechanical Power Extraction ..................................... Future D rive Designs ............................................ Effect of Air and Power Extraction ................................ Redundancy Requirements ....................................... M A INTENANCE ................................................ SUMMATION OF POWER LOSSES .............................. G EN ERA L ...................................................... ENGINE INSTALLATION LOSSES ................................ Air Induction System Pressure Loss ................................ Exhaust Pressure Rise ........................................... Engine Inlet Temperature ........................................ Power Extraction ............................................... Engine A ir Bleed ............................................... A ir Induction Anti-ice ........................................... Charts for Presentation of Installed Power . ......................... LOSSES BETWEEN ENGINE SHAFT AND MAIN ROTOR .......... Transmission Efficiency ......................................... Power Required for Antitorque .................................... A ccessories .... ........................................... .... FUEL AND LUBRICATION SYSTEMS .............................. FUEL SYSTEM REQUIREMENTS ................................. REQUIREMENTS FOR OIL SYSJ"EMS ............................ Oil Tanks ......................................................

Page page 8-7 .8-9 8-8 8-8 8-10 8.I 1 8-12 8-12 8-13 8-13 8-13 8-13 8-13 8-16 8-16 8-16 9-17 8-18 8-19 8-20 . 8.20 8-20 8-20 8-20 8-21 8-21 .8-22 8-22 8-22 8-22 8-23 8-24 8-24 8-24 8-24 8-24 3-25 8-25 8-25 8-25 8-26 8-26 . 8.26 8-26 8-27 8-27 8-27 8-28 8-28 ,

)

S8-2.58-2.5.1 8-2.5.2 8-2.5.3 8-2.5.4 8-2.5.5 8-2.5.6 8-2.6 8-3 8-3.1 8-3.2 8-3.2.1 8-3.2.2 8-3.2.3 8-3.2.4 8-3.2.5 8-3.2.6 8-3.2.7 8-3.3 8-3.3.1 8-3.3.2 8-3.3.3 8-4 8-4.1 8.4.2 8-4.2.1 xx

A,

AMCP 706-201

)Paragraph8-4.2.2 8.4.2.3 8-4.2.4 8.5 8-5.1 8-5.2 8-5.3 8-5.4 8.5.5 8-68-6.1

TABLE OF CONTENTS (Continued)PageOil Lines and Couplings ......................................... Other Oil System Components .................................... Oil Cooler .................................................... PROPULSION SYSTEM FIRE PROTECTION ........................ G EN ER A L ...................................................... FIRE PREVENTION ............................................. FIRE CONTAINMENT . .......................................... FIRE DETECTION SYSTEMS ..................................... FIRE EXTINGUISHING SYSTEMS ................................ ENGINE-STARTING SYSTEMS .....................................G EN ERA L ......................................................

8.28 8-48 8-28 8.28 8-28 8.28 8.29 8-29 8.29 8-298.29

8-6.2 8-6.2.1 8-6.2.2 8-6.2.3 8-6.3 8-6.4 8-6.4.1 8-6.4.1.1 8-6.4.1.2 8-6.4.1.3

S8-6.4.28.6.4.2.1 8-6.4.2.2 8-6.4.2.3 8.6.4.2.4

8-6.4.2.4.1

STARTING SYSTEM SELECTION ................................. Engine Parameters .............................................. Starter Parameters ............................................. Self-contained Power Sources ..................................... CARTRIDGE-BOOSTED ELECTRICAL STARTING SYSTEMS ....... AUXILIARY POWER UNIT (APU) INSTALLATIONS ............... M ajor APU Types .............................................. Shaft Pow er .................................................. Compressed Air Power ........................................ Compressed Air Bleed Combined With Combustion Products ........ Trade-off Considerations for APU Selection ......................... Self-suffi ciencv ................................................ Ground Support Functions ..................................... Flight or Alternate Support Functions ............................ W eight O ptim ization ........................................... Hydraulic Energy Transfer ...................................... Pneumatic Energy Transfer ..................................... Direct Drive Energy Transfer ................................... Combination Energy Transfer ................................... Space Optm bi,n a tion ............................................ APU Perform ance .............................................

.

.

8-6.4.2.4.2 8-6.4.2.4.3 8-6.4.2.4.4 8-6.4.2.4.5 8-6.4.2.5 8-6.4.2.6 8-6.4.3 8-7 8-7.1 8.7.2 8-7.3 8-7.4 9.7.5 8-7.5.1 8-7.5.2 8-7.5.3 8-7. 8-7.7 8-7.7.1 8-7.7.2 8-7.7.3 8..7-7.4

Electrical Energy Transfer ......................................

8-30 8.30 8.31 8-31 8-33 8-33 8-33 8-33 8.34 8.34 8-34 8-34 8-34 8-34 8-35

8-35

8.35 8-35 8-35 8-35 8-35 8-36 8-36 8-36 8-36 8.36 8.36 8-37 8.37 8.37 8-378.38

APU/Helicopter Interface Considerations ........................... ENGINE/AIRFRAME INTEGRATED CONTROL SYSTEM ............ GENERAL ..................................................... ROTOR SPEED REQUIREMENTS .................................. POWER MANAGEMENT REQUIREMENTS ....................... ENGINE LIMIT CONTROL REQUIREMENTS ..................... INTEGRATED CONTROL REQUIREMENTS ...................... Proportional Control System ...................................... Rotor System Response ............................ ..............Engine and Rotor Dam ping ........................ ..............

ENGINE RESPONSE. ................... ......................... COLLECTIVE PITCH SIGNAl ............ ........................ Variable G ain D evice,. ........................................... Slow Time Constant Governor% ................................... ,,c% hronou, C ontrok ........................................... Load-,haring ...................................................

8-39 8 41 8-41 8 -41 8-41 8-42xxi

AMCP 706.201

TABLE OF CONTENTS (Continued)Paragraph Page NONLINEAR ANALYSIS ........................................ EMERGENCY AND AUTHORITY LIMITATIONS .................. ENGINE STARTING AND POWER CONTROL LEVER SYSTEMS LIST OF SYM BOLS ................................................ REFERENCES ................................................ 8-42 8-42 8-43 8-46 8.46

(U

8.7.88.7.9 8-7.10 8&8

CHAPTER 9 SECONDARY POWER SYSTEMS 9-1 9-2 9-2.1 9-2.1.1 9-2.1.2 9-2.2 9-2.2.1 9-2.2.1.1 9-2.2.1.2 9-2.2.1.3 9-2.2.1.4 9-2.2.1.5 9-2.2.2 9-3 9-3.1 9-3.1.1 9-3.1.2 9-3.1.3 9.3.1.3.1 9-3.1.3,2 9-3.1.3.3 9-3.1.3.4 9-3.1.3.5 9-3.2 9-3.2.1 9-3.2.2 9-3.3 9-3.3.1 9-3.3.2 9-3.4 4-3.5 9-3.6 9-3.6.1 9-3.6.2 9-3.7 9-3.7.1 9-3.7.2 9-3.7.3 9.3.8i xxii

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INTROD UCTION ................................................. SU?3SYSTEM SELECTION .......................................... G EN ER A L .................................. ................... Maintainability and Reliability Considerations ....................... Safety ................................... ........... ......... PERFORMANCE CALCULATIONS ............................... Takeoff W eight Penalty Method ................................... Fixed W eight Penalty .......................................... Variable W eight Penalty ........................................ Ram Air Drag Penalty ......................................... Bleed Air Penalty ............................................. Shaft Horsepower Extraction Penalty ............................. Breguet Range Equation ......................................... ELECTRICAL SYSTEMS ........................................... GENERAL .................................................... Electrical Load Analysis ......................................... DC System s .................................................... AC Systems ................................................... Constant-speed Drive System .................................... Air Turbine System ........................................... Controlled-speed Hydraulic Motor System ......................... Cycloconverter System ....... ................................. High-voltage DC System ....................................... DC ELECTRICAL SYSTEMS ...................................... System Description .............................................. W eight A nalysis .... ........................................... VARIABLE-FREQUENCY AC ELECTRICAL SYSTEM .............. System Description .............................................. Weight Analysis ............................................... CONSTANT-FREQUENCY AC SYSTEM ........................... W EIGHT COMPARISON ......................................... CF AC SYSTEM WITH ONBOARD APU ........................... System Description .............................................. W eight A nalysis ................................................ PROTECTION ................................................... Direct Current System Protection .................................. Isolated AC System Protection .................................... Parallel AC System Protection .................................... PARALI EL VERSUS NONPARALLEL OPERATION ...............

.

9-1 9-2 9-2 9.2 9-i. 9-_ 9-3 9-3 9-3 9-4 9.4 9-4 9-5 9-5 ..9-1 9-5 9-5 9-6 9-6 9-6 9.6 9-6 9-6 9-6 9-6 9-7 9-10 9-10 9-10 9-10 9-11 9-13 9-13 9-13 9-14 9-14 9-15 9-17 9-18

AMCP 706-201

TABLE OF CONTENTS (Continued)Paragraph 9-3.8.1 9-3.8.2 9-3.9 9-3.10 9-3.11 9-3.12 9-3.13 9-4 9-4.1 9-4.2 9-4.2.1 9-4.2.2 9-4.2.2.19-4.2.2.2 9-4.2.2.3 9-4.2.3 9-4.2.4 9-4.2.5 9-4.2.6 9-4.2.7 9-4.2.8 9-4.2.9 9-4.3 9-4 .3.1 94 .3.2 9-4.3.3 9-4.3.4 9-4.4 9-4.4.1 9-4.4.2 9-4.4.3 9-4.4.4 94.4.5 9-4.4.6 9-4.4.7 9.4.4.7.1 9-4 .4.7.2 9-4.4.7.3 9-4.4.8 9-4.4.8.1 94.4.8.2 9-4.4.9 9-4.5 9-4.5.1 9-4.5.2 9-4.5.3

Page Parallel Operation ............................................... Nonparallel Operation ........................................... ELECTRICAL SYSTEM RELIABILITY ............................ ELECTRICAL SYSTEM SAFETY .................................. EMERGENCY SYSTEMS ......................................... DISTRIBUTION SYSTEM ........................................ ELECTROMAGNETIC COMPATIBILITY (EMC) ................... HYDRAULIC SYSTEMS ........................................... G ENERAL ...................................................... TRADE-OFF CONSIDERATIONS ................................. Mission 11erformance Requirements ................................ System Trade-offs ............................................... System Pressure Tende-offs .....................................Trade-offs Among Constant-pressure, Variable-flow; Constant-flow; and Load-sensitive Systems .................. ..................... Central Hydraulic Systems Versus Remotely Located Packaged Hydraulic System s ..................................................... System Filtration Trade-offs ...................................... Fluid Selection ............................................... Survivability/reliability Trade-offs ................................. System Reservoir Trade-off ....................................... Line Size Optimization ........................................... System Packaging Trade-offs ...................................... System Line and Fitting Tradeoff ................................. SURVEY OF MILITARY SPECIFICATION REQUIREMENTS ...... System Type ................................................... System Class ................................................... System Operation ............................................... System/Component Design ....................................... DESIGN FEATURES ............................................. Pum ps ........................................................ Reservoirs ..................................................... Accumulators .................................................. System Pressure Relief Valves ..................................... Filters ......................................................... Statie and Dynamic Seals ........................................ Distribution System ............................................. Fittings ...................................................... Tubing ...................................................... Hose Assemblies .............................................. Functional Subsystems ........................................... Flight Control Subsystems ...................................... Utility Systems ............................................... Engine-starting Systems .......................................... SAFETY. OPERATIONAL RELIABILITY, AND SURVIVABILITY CONSIDERATIONS ................................................. Routing the System ............................................. Component and Subsystem Design ................................. Instrumentation .................................................

9-18 9.19 9-19 9-199-19

9-20 9-20 9-21 9-21 9-21 9-21 9-21 9-219-22 9-22 9-23 .. 9-3 9-23 9-24 9-24 9-25 9-25 9.26 9-26 9-27 9-27 9-27 9-27 9-27 9-28 9-29 9-30 9-31 9-31 9-32 9-32 9-32 9-33 9-33 9-33 9-33 9-34 9-35 9-35 9-35 9-37 xxiii

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'. ". ":"..... ~.. . , .i".... . ............ ". ....... '" .... . ' . . " """......' . , . "'" . . .

.

.. ' . ..-............ . 1; empirical methods, discussed insucceeding paragraphs, should be used at lower

and where CC ACq are given by

ROTOR(4L-

R G - ROUND PLANE IMAGE

ROTOR HEIGHTP.

g3-14. Replasemat of Rotor and Ground by = Cylinda Vortex ad ImamVert"

heights. Theoretical ground effect corrections involve ideal rotors, and do not accountfor all factors that influence the rotor wake. To develop realistic analytical models, flight test data and small-scale investigations have been used to determine empirical modifications to theoretical ground effect equations. Cheeseman and Gregory (Rtd. 20) have used a mirror image rotor system theoretical upproach and single rotor helicopter test data to develop an empirical relationship. By use of the ideal power relationship, which states that the main rotor power equals the product of the rotor thrust and the induced velocity, the thrust augmentation ratio can be expressed as 'T. = v.,v at a constant power. The velocity induced at the center of the rotor by its mirror image is 3-11

AMCP 706-201Z ROTOR HE IGHT ABOVE "=+

R- RA+ ROO21 // / ; , .. _rl /efficiency where

16(ZR)= l +(V/,)=I16 Z/ ) [ I

dless (3-26)

Sd,;1.. , F-- 08 " 0.4 iCT'

+ 0.5 ' ,..v.. 1 i .5, 1-2.5---, 3.5 1 I

'

S

"qc =Cheeseman forward Rlight factor In hover V = 0 and when C(0.25,qc,a V'o-)'l a] = 1, Eq. 3-26 approximates Eq. 3-24. The Cheeseman equation correlates well for lightly loaded rotors. For'higher disk loadings, however, the equation is somewhat optimistic and flight data shoul

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Engineering.design.handbook.helicopter.engineering.part.I