Chapter
1.4 Simple Guide to the Book
Chapter 2 Helicopter and Tiltrotor Flight Dynamics - An Introductory Tour
2.2 Four Reference Points
2.2.1 The Mission and Piloting Tasks
2.2.2 The Operational Environment
2.2.3 The Vehicle Configuration, Dynamics, and Flight Envelope
Two Distinct Flight Regimes
2.2.4 The Pilot and Pilot-Vehicle Interface
2.2.5 Résumé of the Four Reference Points
2.3 Modelling Helicopter/Tiltrotor Flight Dynamics
2.3.2 Multiple Interacting Subsystems
2.3.3 Trim, Stability, and Response
2.3.4 The Flapping Rotor in a Vacuum
2.3.5 The Flapping Rotor in Air - Aerodynamic Damping
2.3.6 Flapping Derivatives
2.3.7 The Fundamental 90∘ Phase Shift
2.3.8 Hub Moments and Rotor/Fuselage Coupling
2.3.9 Linearization in General
2.3.10 Stability and Control Résumé
2.3.11 The Static Stability Derivative Mw
2.3.12 Rotor Thrust, Inflow, Zw, and Vertical Gust Response in Hover
2.3.13 Gust Response in Forward Flight
2.3.14 Vector-Differential Form of Equations of Motion
2.3.16 Inverse Simulation
2.4.2 Quantifying Quality Objectively
2.4.3 Frequency and Amplitude - Exposing the Natural Dimensions
2.4.4 Stability - Early Surprises Compared with Aeroplanes
2.4.5 Pilot-in-the-Loop Control; Attacking a Manoeuvre
2.4.6 Bandwidth - A Parameter for All Seasons?
2.4.7 Flying a Mission Task Element
2.4.8 The Cliff Edge and Carefree Handling
2.4.11 Inceptors and Displays
2.4.12 Operational Benefits of Flying Qualities
2.4.13 Flying Qualities Review
2.5 Design for Flying Qualities; Stability and Control Augmentation
2.5.1 Impurity of Primary Response
2.5.2 Strong Cross-Couplings
2.5.3 Response Degradation at Flight Envelope Limits
2.5.5 The Rotor as a Control Filter
2.5.6 Artificial Stability
2.6 Tiltrotor Flight Dynamics
Chapter 3 Modelling Helicopter Flight Dynamics: Building a Simulation Model
3.1 Introduction and Scope
3.2 The Formulation of Helicopter Forces and Moments in Level 1 Modelling
Blade Flapping Dynamics - Introduction
The Centre-Spring Equivalent Rotor
Momentum Theory for Axial Flight
Momentum Theory in Forward Flight
Local-Differential Momentum Theory and Dynamic Inflow
Rotor Flapping-Further Considerations of the Centre-Spring Approximation
Rotor in-Plane Motion: Lead-Lag
Ground Effect on Inflow and Induced Power
3.2.3 Fuselage and Empennage
The Fuselage Aerodynamic Forces and Moments
The Empennage Aerodynamic Forces and Moments
3.2.4 Powerplant and Rotor Governor
3.2.5 Flight Control System
3.3 Integrated Equations of Motion of the Helicopter
3.4 Beyond Level 1 Modelling
3.4.1 Rotor Aerodynamics and Dynamics
Modelling Section Lift, Drag, and Pitching Moment
Modelling Local Incidence
3.4.2 Interactional Aerodynamics
Appendix 3A Frames of Reference and Coordinate Transformations
3A.1 The Inertial Motion of the Aircraft
3A.2 The Orientation Problem - Angular Coordinates of the Aircraft
3A.3 Components of Gravitational Acceleration along the Aircraft Axes
3A.4 The Rotor System - Kinematics of a Blade Element
3A.5 Rotor Reference Planes - Hub, Tip Path, and No-Feathering
Chapter 4 Modelling Helicopter Flight Dynamics: Trim and Stability Analysis
4.1 Introduction and Scope
4.2.1 The General Trim Problem
4.2.2 Longitudinal Partial Trim
4.2.3 Lateral/Directional Partial Trim
4.2.4 Rotorspeed/Torque Partial Trim
4.2.5 Balance of Forces and Moments
4.2.6 Control Angles to Support the Forces and Moments
The Translational Velocity Derivatives
The Derivatives Xu, Yv, Xv, and Yu (Mv and Lu)
The Derivatives Mu and Mw
The Derivatives Mw, Mv, and Mv
The Derivatives Nu, Nw, Lu, Lw
The Angular Velocity Derivatives
The Derivatives Mq, Lp, Mp, Lq
The Derivatives Nr, Lr, Np
The Derivatives Z𝜃0, Z𝜃1s
The Derivatives M𝜃1s, M𝜃1c, L𝜃1s, L𝜃1c
The Derivatives Y𝜃OT, L𝜃OT, N𝜃OT
The Effects of Nonuniform Rotor Inflow on Damping and Control Derivatives
Some Reflections on Derivatives
4.3.3 The Natural Modes of Motion
The Lateral/Directional Modes
Appendix 4A The Analysis of Linear Dynamic Systems (with Special Reference to 6-Dof Helicopter Flight)
Appendix 4B The Three Case Helicopters: Lynx, Bo105 and Puma
4B.1 Aircraft Configuration Parameters
The RAE (DRA) Research Lynx, ZD559
The DLR Research Bo105, S123
The RAE (DRA) Research Puma, XW241
Fuselage Aerodynamic Characteristics
Empennage Aerodynamic Characteristics
4B.2 Stability and Control Derivatives
4B.3 Tables of Stability and Control Derivatives and System Eigenvalues
Appendix 4C The Trim Orientation Problem
Chapter 5 Modelling Helicopter Flight Dynamics: Stability Under Constraint and Response Analysis
5.1 Introduction and Scope
5.2 Stability Under Constraint
5.2.1 Attitude Constraint
5.2.2 Flight Path Constraint
5.3 Analysis of Response to Controls
5.3.2 Heave Response to Collective Control Inputs
Response to Collective in Hover
Response to Collective in Forward Flight
5.3.3 Pitch and Roll Response to Cyclic Pitch Control Inputs
Response to Step Inputs in Hover - General Features
Effects of Rotor Dynamics
Step Responses in Hover - Effect of Key Rotor Parameters
Response Variations with Forward Speed
Stability Versus Agility - Contribution of the Horizontal Tailplane
5.3.4 Yaw/Roll Response to Pedal Control Inputs
5.4 Response to Atmospheric Disturbances
Modelling Atmospheric Disturbances
Modelling Helicopter Response
Appendix 5A Speed Stability Below Minimum Power; A Forgotten Problem?
Chapter 6 Flying Qualities: Objective Assessment and Criteria Development
6.1 General Introduction to Flying Qualities
6.2 Introduction and Scope: The Objective Measurement of Quality
6.3 Roll Axis Response Criteria
6.3.1 Task Margin and Manoeuvre Quickness
6.3.2 Moderate to Large Amplitude/Low to Moderate Frequency: Quickness and Control Power
6.3.3 Small Amplitude/Moderate to High Frequency: Bandwidth
Early Efforts in the Time Domain
Bandwidth/Phase Delay Boundaries
The Measurement of Bandwidth
6.3.4 Small Amplitude/Low to Moderate Frequency: Dynamic Stability
6.3.5 Trim and Quasi-Static Stability
6.4 Pitch Axis Response Criteria
6.4.1 Moderate to Large Amplitude/Low to Moderate Frequency: Quickness and Control Power
6.4.2 Small Amplitude/Moderate to High Frequency: Bandwidth
6.4.3 Small Amplitude/Low to Moderate Frequency: Dynamic Stability
6.4.4 Trim and Quasi-Static Stability
6.5 Heave Axis Response Criteria
6.5.1 Criteria for Hover and Low-Speed Flight
6.5.2 Criteria for Torque and Rotorspeed During Vertical Axis Manoeuvres
6.5.3 Heave Response Criteria in Forward Flight
6.5.4 Heave Response Characteristics in Steep Descent
6.6 Yaw Axis Response Criteria
6.6.1 Moderate to Large Amplitude/Low to Moderate Frequency: Quickness and Control Power
6.6.2 Small Amplitude/Moderate to High Frequency: Bandwidth
6.6.3 Small Amplitude/Low to Moderate Frequency: Dynamic Stability
6.6.4 Trim and Quasi-Static Stability
6.7 Cross-Coupling Criteria
6.7.1 Pitch-to-Roll and Roll-to-Pitch Couplings
6.7.2 Collective to Yaw Coupling
6.7.3 Sideslip to Pitch and Roll Coupling
6.8 Multi-Axis Response Criteria and Novel-Response Types
6.8.1 Multi-Axis Response Criteria
6.8.2 Novel Response Types
6.9 Objective Criteria Revisited
Chapter 7 Flying Qualities: Subjective Assessment and Other Topics
7.1 Introduction and Scope
7.2 The Subjective Assessment of Flying Quality
7.2.1 Pilot Handling Qualities Ratings - HQRs
7.2.2 Conducting a Handling Qualities Experiment
Designing a Mission Task Element
Evaluating Roll Axis Handling Characteristics
7.3 Special Flying Qualities
Agility as a Military Attribute
Relating Agility to Handling Qualities Parameters
7.3.2 The Integration of Controls and Displays for Flight in Degraded Visual Environments
The Usable Cue Environment
UCE Augmentation with Overlaid Symbology
7.3.3 Carefree Flying Qualities
7.5 The Contribution of Flying Qualities to Operational Effectiveness and the Safety of Flight
Chapter 8 Flying Qualities: Forms of Degradation
8.1 Introduction and Scope
8.2 Flight in Degraded Visual Environments
8.2.1 Recapping the Usable Cue Environment
8.2.2 Visual Perception in Flight Control - Optical Flow and Motion Parallax
8.2.3 Time to Contact; Optical Tau, 𝝉
8.2.4 𝝉 Control in the Deceleration-to-Stop Manoeuvre
8.2.5 Tau-Coupling - A Paradigm for Safety in Action
8.2.6 Terrain-Following Flight in Degraded Visibility
8.3 Handling Qualities Degradation through Flight System Failures
8.3.1 Methodology for Quantifying Flying Qualities Following Flight Function Failures
8.3.2 Loss of Control Function
8.3.3 Malfunction of Control - Hard-Over Failures
8.3.4 Degradation of Control Function - Actuator Rate Limiting
8.4 Encounters with Atmospheric Disturbances
8.4.1 Helicopter Response to Aircraft Vortex Wakes
Analysis of Encounters - Attitude Response
Analysis of Encounters - Vertical Response
8.4.2 Severity of Transient Response
Appendix 8A HELIFLIGHT, HELIFLIGHT-R, and FLIGHTLAB at the University of Liverpool
8A.2 Immersive Cockpit Environment
Chapter 9 Flying Qualities: The Story of an Idea
9.1 Introduction and Scope
9.2 Historical Context of Rotorcraft Flying Qualities
9.2.1 The Early Years; Some Highlights from the 1940s-1950s
9.2.2 The Middle Years - Some Highlights from the 1960s-1970s
9.3 Handling Qualities as a Performance Metric - The Development of ADS-33
9.3.1 The Evolution of a Design Standard - The Importance of Process
9.3.2 Some Critical Innovations in ADS-33
9.5 Roll Control; A Driver for Rotor Design
9.6.1 ADS-33 Tailoring and Applications
9.6.2 Handling Qualities as a Safety Net; The Pilot as a System Component
9.7 The Future Challenges for Rotorcraft Handling Qualities Engineering
Chapter 10 Tiltrotor Aircraft: Modelling and Flying Qualities
10.1 Introduction and Scope
10.2 Modelling and Simulation of Tiltrotor Aircraft Flight Dynamics
10.2.1 Building a Simulation Model
Multi-Body Dynamic Modelling
FXV-15 Model Components and Data
Gimballed Proprotor Family
Power Plant and Transmission Family
Flight Control System Family
10.2.2 Interactional Aerodynamics in Low-Speed Flight
10.2.3 Vortex Ring State and the Consequences for Tiltrotor Aircraft
10.2.4 Trim, Linearisation, and Stability
10.3 The Flying Qualities of Tiltrotor Aircraft
10.3.2 Developing Tiltrotor Mission Task Elements
Acceleration-Deceleration Characteristics
Tolerance in the Transition Programme
Rate of Pitch Control Movement
10.3.3 Flying Qualities of Tiltrotors; Clues from the Eigenvalues
10.3.4 Agility and Closed-Loop Stability of Tiltrotors
Lateral-Directional Agility and Closed-Loop Stability
Longitudinal Pitch-Heave Agility and Closed-Loop Stability
10.3.5 Flying Qualities during the Conversion
10.3.6 Improving Tiltrotor Flying Qualities with Stability and Control Augmentation
V-22 Power Management and Control
Unification of Flying Qualities
Flying Qualities of Large Civil Tiltrotor Aircraft
10.4 Load Alleviation versus Flying Qualities for Tiltrotor Aircraft
10.4.1 Drawing on the V-22 Experience
Transient Driveshaft and Rotor Mast Torque
Oscillatory Yoke In-plane/Chordwise Bending
Nacelle Conversion Actuator Loads
10.4.2 Load Alleviation for the European Civil Tiltrotor
Modelling for SLA - Oscillatory Yoke (Chordwise) Bending Moments
10.5 Chapter Epilogue; Tempus Fugit for Tiltrotors
Appendix 10A Flightlab Axes Systems and Gimbal Flapping Dynamics
10A.1 FLIGHTLAB Axes Systems
10A.2 Gimbal Flapping Dynamics
Appendix 10B The XV-15 Tiltrotor
Aircraft Configuration Parameters
XV-15 Control Ranges and Gearings
10C.2 FXV-15 Stability and Control Derivative and Eigenvalue Tables
Helicopter Mode (Matrices Shown with and without (nointf) Aerodynamic Interactions)
Appendix 10D Proprotor Gimbal Dynamics in Airplane Mode
Appendix 10E Tiltrotor Directional Instability Through Constrained Roll Motion: An Elusive, Paradoxical Dynamic
10E.1 Background and the Effective Directional Stability
10E.2 Application to Tiltrotors
Helicopter Flight Dynamics
：Including a Treatment of Tiltrotor Aircraft
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