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ENAE 631

HELICOPTER AERODYNAMICS I

The objectives of this course are to provide an introductory treatment of the aerodynamic theory of rotary-wing aircraft, including basic performance, control, and basic rotor dynamics. Prerequisites are a understanding of elementary aerodynamics and dynamics. Students should have taken two courses in aerodynamics at the undergraduate level. Students should also have an elementary background in computer programming.

Instructor
Office Hours
Email
Assessment Method
Homework Policy
Homework Problem Sets
Technical Essay
Exams
Textbooks
History of Rotorcraft
Specialist Topics
Course Outline

Instructor:

Prof. J. Gordon Leishman, Room 3179C,

Office Hours:

Open. Unavailable Tuesday and Thursdays until 11am (Reserved for ENAE 488A students). Only by prior appoinments on Fridays. Otherwise, you are welcome to come and see the instructor at anytime during regular office hours, workload permitting. Call or email first!

Email:

Students may use email as a means of interacting with the instructor. Make sure you have a computer account. Class announcements will often be made by email. Click here to email: J. Gordon Leishman.

Please do not send homework assignments by email (see homework requirements below).

Assessment Method:

Homework (70%)
Technical Essay (15%)
Final Exam (15%).

Homework Policy:

Homework is assigned (posted on the web page) about every other week, usually on a Tuesday.
Homework must be submitted one-week after it is assigned.
Submission of homework is mandatory.
Homework is expected to be done carefully and neatly, and submitted on-time.
Improperly done homework will be returned for correction and resubmision. Resubmissions may not be graded until the next batch of homework.
Students taking the course over instructional television (ITV) MUST submit all their assignments through ITV, or can mail the assignments directly to the instructor by regular US mail if submission through ITV is not possible. The homework must be dated as received by ITV or postmarked by the due date. DO NOT send homework by FAX.
Time-extensions for homework submissions will be granted, but only on a case by case basis. Homework submitted after the due date and without a time extension will receive no credit.

Homework Problem Sets (posted here when made available)

Homework #1. Posted 9/1/05. Due 9/13/05.

Homework #2. Posted 9/16/05. Due 9/27/05.

Homework #3. Posted 10/7/05. Due 10/17/05

Homework #4. Posted 10/18/05. Due 11/1/05

Homework #5. Posted 11/17/05. Due 11/24/05

Homework #6. Posted 11/29/05. Due 12/08/05

Download Introductory Slides for ENAE 631 here:

For Part 1 of the introductory slide presentation click here.
For Part 2 of the introductory slide presentation click here.
For a paper on the technical development of the autogiro, click here.

Technical Essay:

The Technical Essay will be due for submission on 11/22/05. NO EXTENSIONS.
The essay title must be submitted to the instructor for approval no later than 9/30/05
The essay can be on any subject related to rotorcraft technology, but must have relevance to aerodynamics.
For further details on the essay requirements, click here.

Exams:

There is no mid-term exam for the Fall 2004 semester.
The final exam is 12/16/04 at 10:30am.

Textbooks:

Primary textbook is: Principles of Helicopter Aerodynamics (Hardback) Cambridge University Press, ISBN: 0-5216606-0-2 or Paperback edition ISBN: 0-5215239-6-6.
The classic text on the subject is: Aerodynamics of the Helicopter by Gessow and Myers. Although the nomenclature is a little out of date, this text provides a solid coverage of the basic material.
A primary reference text will be Helicopter Theory by Johnson. This is the definitive reference for modern helicopter analyses. An inexpensive Dover publication of this book is now available.
Other useful books are: Rotary Wing Aerodynamics by Stepniewski and Keys, Helicopter Performance, Stability and Control by Prouty, and The Foundations of Helicopter Flight by Newman. The latter text is very modern and provides excellent coverage for an introductory course.

HISTORY OF ROTORCRAFT:

The ideas of vertical flight can be traced back to early Chinese tops, a toy first used about 400 BC. Amongst his many elaborate drawings, the Renaissance visionary Leonardo da Vinci shows what is a basic human-carrying helicopterlike machine. His sketch of the "aerial-screw" or "air gyroscope" device is dated to 1483 but it was first published nearly three centuries later. Da Vinci clearly did not build his machine, except perhaps for some small models, but his idea was clearly far ahead of its time. Read more....

Specialist Topics:

Course outline (not necessarily covered in order stated):

1. Introduction: A History of Helicopter Flight

Early Attempts at Vertical Flight
The Era of the Autogiro
The First Successes With Helicopters
Maturing Technology
Tilt-Wings and Tilt-Rotors

2. Fundamentals of Rotor Aerodynamics

Flow Near a Hovering Rotor
Conservation Laws of Fluid Mechanics
Application to a Hovering Rotor
Disk Loading and Power Loading
Induced Inflow Ratio
Thrust and Power Coefficients
Non-Ideal Effects on Rotor Performance
Figure of Merit
Induced Tip-Loss
Rotor Solidity and Blade Loading Coefficient
Power Loading
Axial Climb & Descent
Working States of the Rotor in Axial Flight
Autorotation
Momentum Analysis in Forward Flight
Induced Velocity in Forward Flight
Numerical Solution to Inflow Equation
Validity of the Inflow Equation
Rotor Power in Forward Flight
Other Applications of the Momentum Theory

3. 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
Ideal Twist
BEM Theory - A Numerical Approach
Distributions of Inflow and Airloads
The Optimum Hovering Rotor
Circulation Theory of Lift
Power Estimates
Prandtl's Tip Loss Function
Figure of Merit
Compressibility Corrections
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
Blade Forces
Induced Velocity Field

4. Rotating Blade Motion

Types of Rotors
Equilibrium About the Flapping Hinge
Equilibrium About the Lead/Lag Hinge
Equation of Motion for Flapping Blade
Physical Description of Blade Flapping

Coning Angle
Longitudinal Flapping
Lateral 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 Hinge Offset
Coupled Flap-Lag Motion
Introduction to Rotor Trim

5. Basic Helicopter Performance

Hovering and Axial Climb Performance
Forward Flight Performance

Induced Power
Blade Profile Power
Parasitic Power
Climb Power
Tail Rotor Power
Total Power

Effect of Gross Weight
Effect of Density Altitude
Lift-to-Drag Ratios
Climb Performance
Speed for Minimum Power
Speed for Maximum Range
Range-Payload and Endurance-Payload
Factors Affecting Maximum Attainable Forward Speed
Performance of Co-Axials and Tandems
Autorotation Revisited

Autorotation in Forward Flight
Height-Velocity (HV) Curve
Autorotation Index

Ground Effect

6. Conceptual Design of Helicopters

Design Requirements
Design of the Main Rotor

Rotor Diameter
Tip Speed
Rotor Solidity
Number of Blades
Blade Twist
Blade Planform & Tip Shape
Airfoil Sections
The BERP Rotor

Fuselage Design

Fuselage Drag
Vertical Drag or Download
Fuselage Side-Force

Empennage Design

Horizontal Stabilizer
Vertical Stabilizer
Modeling

Design of Tail Rotors

Physical Size
Thrust Requirements
Pushers Versus Tractors
Design Requirements
Aerodynamic Interactions
Typical Tail Rotor Designs

Other Anti-Torque Devices

Fan-in-Fin
NOTAR

High Speed Rotorcraft

Compound Helicopters
Tilt Rotors
Other High Speed Rotorcraft

Go back to the Rotorcraft Aerodynamics main page