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Principles of Helicopter Aerodynamics

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ISBN-10: 0521858607

ISBN-13: 9780521858601

Edition: 2nd 2005 (Revised)

Authors: J. Gordon Leishman, Michael J. Rycroft, Wei Shyy

List price: $185.00
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This volume provides a thorough, modern treatment of the aerodynamic principles of helicopters and other rotating-wing vertical lift aircraft.
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Book details

List price: $185.00
Edition: 2nd
Copyright year: 2005
Publisher: Cambridge University Press
Publication date: 4/24/2006
Binding: Mixed Media
Pages: 864
Size: 7.50" wide x 10.75" long x 1.75" tall
Weight: 3.542
Language: English

J. Gordon Leishman is the Minta Martin Chair of Engineering and Professor of Aerospace Engineering at the University of Maryland. He is a former aerodynamicist at Westland Helicopters and has written extensively on topics in helicopter aerodynamics. Dr Leishman is a Fellow of the Royal Aeronautical Society and an Associate Fellow of the American Institute of Aeronautics and Astronautics. He is also Editor-in-Chief for the Journal of the American Helicopter Society.

Preface to the Second Edition
Preface to the First Edition
List of Main Symbols
Introduction: A History of Helicopter Flight
Rising Vertically
Producing Thrust
Key Technical Problems in Attaining Vertical Flight
Early Thinking
The Hoppers
The First Hoverers
Not Quite a Helicopter
Engines: A Key Enabling Technology
On the Verge of Success
The First Successes
Toward Mass Production
Maturing Technology
Compounds, Tilt-Wings, and Tilt-Rotors
Chapter Review
Fundamentals of Rotor Aerodynamics
Momentum Theory Analysis in Hovering Flight
Flow Near a Hovering Rotor
Conservation Laws of Aerodynamics
Application to a Hovering Rotor
Disk Loading and Power Loading
Induced Inflow Ratio
Thrust and Power Coefficients
Comparison of Theory with Measured Rotor Performance
Nonideal Effects on Rotor Performance
Figure of Merit
Estimating Nonideal Effects from Rotor Measurements
Induced Tip Loss
Rotor Solidity and Blade Loading Coefficient
Power Loading
Momentum Analysis in Axial Climb and Descent
Axial Climb
Axial Descent
Region between Hover and Windmill State
Power Required in Axial Climbing and Descending Flight
Four Working States of the Rotor in Axial Flight
Vortex Ring State
Momentum Analysis in Forward Flight
Induced Velocity in Forward Flight
Special Case, [alpha] = 0
Numerical Solution to Inflow Equation
General Form of the Inflow Equation
Validity of the Inflow Equation
Rotor Power Requirements in Forward Flight
Other Applications of the Momentum Theory
Coaxial Rotor Systems
Tandem Rotor Systems
Chapter Review
Blade Element Analysis
Blade Element Analysis in Hover and Axial Flight
Integrated Rotor Thrust and Power
Thrust Approximations
Torque-Power Approximations
Tip-Loss Factor
Blade Element Momentum Theory (BEMT)
Assumed Radial Distributions of Inflow on the Blades
Radial Inflow Equation
Ideal Twist
BEMT: Numerical Solution
Distributions of Inflow and Airloads
Effects of Swirl Velocity
The Optimum Hovering Rotor
Circulation Theory of Lift
Power Estimates for the Rotor
Prandtl's Tip-Loss Function
Blade Design and Figure of Merit
BEMT in Climbing Flight
Further Comparisons of BEMT with Experiment
Compressibility Corrections to Rotor Performance
Equivalent Blade Chords and Weighted Solidity
Mean Wing Chords
Thrust Weighted Solidity
Power-Torque Weighted Solidity
Weighted Solidity of the Optimum Rotor
Weighted Solidities of Tapered Blades
Mean Lift Coefficient
Blade Element Analysis in Forward Flight
Determining Blade Forces
Definition of the Approximate Induced Velocity Field
Chapter Review
Rotating Blade Motion
Types of Rotors
Equilibrium about the Flapping Hinge
Equilibrium about the Lead-Lag Hinge
Equation of Motion for a Flapping Blade
Physical Description of Blade Flapping
Coning Angle
Longitudinal Flapping Angle
Lateral Flapping Angle
Higher Harmonics of Blade Flapping
Dynamics of Blade Flapping with a Hinge Offset
Blade Feathering and the Swashplate
Review of Rotor Reference Axes
Dynamics of a Lagging Blade with a Hinge Offset
Coupled Flap-Lag Motion
Coupled Pitch-Flap Motion
Other Types of Rotors
Teetering Rotor
Semi-Rigid or Hingeless Rotors
Introduction to Rotor Trim
Equations for Free-Flight Trim
Typical Trim Solution Procedure for Level Flight
Chapter Review
Helicopter Performance
The International Standard Atmosphere
Hovering and Axial Climb Performance
Forward Flight Performance
Induced Power
Blade Profile Power
Compressibility Losses and Tip Relief
Reverse Flow
Parasitic Power
Climb Power
Tail Rotor Power
Total Power
Performance Analysis
Effect of Gross Weight
Effect of Density Altitude
Life-to-Drag Ratios
Climb Performance
Engine Fuel Consumption
Speed for Minimum Power
Speed for Maximum Range
Range-Payload and Endurance-Payload Relations
Maximum Altitude or Ceiling
Factors Affecting Maximum Attainable Forward Speed
Performance of Coaxial and Tandem Dual Rotor Systems
Autorotational Performance
Autorotation in Forward Flight
Height-Velocity (H-V) Curve
Autorotation Index
Vortex Ring State (VRS)
Quantification of VRS Effects
Implications of VRS on Flight Boundary
Ground Effect
Hovering Flight Near the Ground
Forward Flight Near the Ground
Performance in Maneuvering Flight
Steady Maneuvers
Transient Maneuvers
Factors Influencing Performance Degradation
Chapter Review
Aerodynamic Design of Helicopters
Overall Design Requirements
Conceptual and Preliminary Design Processes
Design of the Main Rotor
Rotor Diameter
Tip Speed
Rotor Solidity
Number of Blades
Blade Twist
Blade Planform and Tip Shape
Airfoil Sections
Case Study: The BERP Rotor
Fuselage Aerodynamic Design Issues
Fuselage Drag
Vertical Drag and Download Penalty
Vertical Drag Recovery
Fuselage Side-Force
Empennage Design
Horizontal Stabilizer
Vertical Stabilizer
Role of Wind Tunnels in Aerodynamic Design
Design of Tail Rotors
Physical Size
Thrust Requirements
Precessional Stall Issues
"Pushers" versus "Tractors"
Design Requirements
Representative Tail Rotor Designs
Other Anti-Torque Devices
NOTAR Design
High-Speed Rotorcraft
Compound Helicopters
Other High-Speed Concepts
Smart Rotor Systems
Human-Powered Helicopter
Hovering Micro Air Vehicles
Chapter Review
Aerodynamics of Rotor Airfoils
Helicopter Rotor Airfoil Requirements
Reynolds Number and Mach Number Effects
Reynolds Number
Concept of the Boundary Layer
Mach Number
Model Rotor Similarity Parameters
Airfoil Shape Definition
Airfoil Pressure Distributions
Pressure Coefficient
Critical Pressure Coefficient
Synthesis of Chordwise Pressure
Measurements of Chordwise Pressure
Aerodynamics of a Representative Airfoil Section
Integration of Distributed Forces
Pressure Integration
Representative Force and Moment Results
Pitching Moment and Related Issues
Aerodynamic Center
Center of Pressure
Effect of Airfoil Shape on Pitching Moment
Use of Trailing Edge Tabs
Reflexed Airfoils
Maximum Lift and Stall Characteristics
Effects of Reynolds Number
Effects of Mach Number
Advanced Rotor Airfoil Design
Representing Static Airfoil Characteristics
Linear Aerodynamic Models
Nonlinear Aerodynamic Models
Table Look-Up
Direct Curve Fitting
Beddoes Method
High Angle of Attack Range
Circulation Controlled Airfoils
Very Low Reynolds Number Airfoil Characteristics
Effects of Damage on Airfoil Performance
Chapter Review
Unsteady Airfoil Behavior
Sources of Unsteady Aerodynamic Loading
Concepts of the Blade Wake
Reduced Frequency and Reduced Time
Unsteady Attached Flow
Principles of Quasi-Steady Thin-Airfoil Theory
Theodorsen's Theory
Pure Angle of Attack Oscillations
Pure Plunging Oscillations
Pitching Oscillations
The Returning Wake: Loewy's Problem
Sinusoidal Gust: Sears's Problem
Indicial Response: Wagner's Problem
Sharp-Edged Gust: Kussner's Problem
Traveling Sharp-Edged Gust: Miles's Problem
Time-Varying Incident Velocity
General Application of the Indicial Response Method
Recurrence Solution to the Duhamel Integral
State-Space Solution for Arbitrary Motion
Indicial Method for Subsonic Compressible Flow
Approximations to the Indicial Response
Indicial Lift from Angle of Attack
Indicial Lift from Pitch Rate
Determination of Indicial Function Coefficients
Indicial Pitching Moment from Angle of Attack
Indicial Pitching Moment from Pitch Rate
Unsteady Axial Force and Airfoil Drag
State-Space Aerodynamic Model for Compressible Flow
Comparison with Experiment
Nonuniform Vertical Velocity Fields
Exact Subsonic Linear Theory
Approximations to the Sharp-Edged Gust Functions
Response to an Arbitrary Vertical Gust
Blade-Vortex Interaction (BVI) Problem
Convecting Vertical Gusts in Subsonic Flow
Time-Varying Incident Mach Number
Unsteady Aerodynamics of Flaps
Incompressible Flow Theory
Subsonic Flow Theory
Comparison with Measurements
Principles of Noise Produced by Unsteady Forces
Retarded Time and Source Time
Wave Tracing
Trace or Phase Mach Number
Ffowcs-Williams-Hawkins Equation
BVI Acoustic Model Problem
Comparison of Aeroacoustic Methods
Methods of Rotor Noise Reduction
Chapter Review
Dynamic Stall
Flow Morphology of Dynamic Stall
Dynamic Stall in the Rotor Environment
Effects of Forcing Conditions on Dynamic Stall
Modeling of Dynamic Stall
Semi-Empirical Models of Dynamic Stall
Capabilities of Dynamic Stall Modeling
Future Modeling Goals with Semi-Empirical Models
Torsional Damping
Effects of Sweep Angle on Dynamic Stall
Effect of Airfoil Shape on Dynamic Stall
Three-Dimensional Effects on Dynamic Stall
Time-Varying Velocity Effects on Dynamic Stall
Prediction of In-Flight Airloads
Stall Control
Chapter Review
Rotor Wakes and Blade Tip Vortices
Flow Visualization Techniques
Natural Condensation Effects
Smoke Flow Visualization
Density Gradient Methods
Characteristics of the Rotor Wake in Hover
General Features
Wake Geometry in Hover
Characteristics of the Rotor Wake in Forward Flight
Wake Boundaries
Blade-Vortex Interactions (BVIs)
Other Characteristics of Rotor Wakes
Periodicity versus Aperiodicity
Vortex Perturbations and Instabilities
Detailed Structure of the Tip Vortices
Velocity Field
Models for the Tip Vortex
Vorticity Diffusion Effects and Vortex Core Growth
Correlation of Rotor Tip Vortex Data
Flow Rotation Effects on Turbulence Inside Vortices
Vortex Models of the Rotor Wake
Biot-Savart Law
Vortex Segmentation
Governing Equations for the Convecting Vortex Wake
Prescribed Wake Models for Hovering Flight
Prescribed Vortex Wake Models for Forward Flight
Free-Vortex Wake Analyses
Aperiodic Wake Developments
Wake Stability Analysis
Flow Visualization of Transient Wake Problems
Dynamic Inflow
Time-Marching Free-Vortex Wakes
Simulation of Carpenter & Friedovich Problem
General Dynamic Inflow Models
Descending Flight and the Vortex Ring State
Wake Developments in Maneuvering Flight
Chapter Review
Rotor-Airframe Interactional Aerodynamics
Rotor-Fuselage Interactions
Effects of the Fuselage on Rotor Performance
Time-Averaged Effects on the Airframe
Unsteady Rotor-Fuselage Interactions
Fuselage Side-Forces
Modeling of Rotor-Fuselage Interactions
Rotor-Empennage Interactions
Airloads on the Horizontal Tail
Modeling of Rotor-Empennage Interactions
Rotor-Tail Rotor Interactions
Chapter Review
Autogiros and Gyroplanes
The Curious Phenomenon of Autorotation
Review of Autorotational Physics
Rolling Rotors: The Dilemma of Asymmetric Lift
Innovation of the Flapping and Lagging Hinges
Prerotating the Rotor
Autogiro Theory Meets Practice
Vertical Flight Performance of the Autogiro
Forward Flight Performance of the Autogiro
Comparison of Autogiro Performance with the Helicopter
Airfoils for Autogiros
NACA Research on Autogiros
Giving Better Control: Orientable Rotors
Improving Performance: Jump and Towering Takeoffs
Ground and Air Resonance
Helicopters Eclipse Autogiros
Renaissance of the Autogiro?
Chapter Review
Aerodynamics of Wind Turbines
History of Wind Turbine Development
Power in the Wind
Momentum Theory Analysis for a Wind Turbine
Power and Thrust Coefficients for a Wind Turbine
Theoretical Maximum Efficiency
Representative Power Curve for a Wind Turbine
Elementary Wind Models
Blade Element Model for the Wind Turbine
Blade Element Momentum Theory for a Wind Turbine
Effect of Number of Blades
Effect of Viscous Drag
Tip-Loss Effects
Tip Losses and Other Viscous Losses
Effects of Stall
Airfoils for Wind Turbines
Yawed Flow Operation
Vortex Wake Considerations
Unsteady Aerodynamic Effects on Wind Turbines
Tower Shadow
Dynamic Stall and Stall Delay
Advanced Aerodynamic Modeling Requirements
Chapter Review
Computational Methods for Helicopter Aerodynamics
Fundamental Governing Equations of Aerodynamics
Navier-Stokes Equations
Euler Equations
Vorticity Transport Equations
Vortex Methods
Boundary Layer Equations
Potential Equations
Surface Singularity Methods
Thin Airfoil Theory
Lifting-Line Blade Model
Applications of Advanced Computational Methods
Unsteady Airfoil Performance
Tip Vortex Formation
CFD Modeling of the Rotor Wake
Airframe Flows
Vibrations and Acoustics
Ground Effect
Vortex Ring State
Comprehensive Rotor Analyses
Chapter Review