Lecture 1 - Introduction
-
Upload
playboyaero -
Category
Documents
-
view
58 -
download
9
Transcript of Lecture 1 - Introduction
1
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 1
AERSP 407 and AERSP 504Aerodynamics of V/STOL Aircraft
Kenneth S. BrentnerDepartment of Aerospace Engineering
The Pennsylvania State University
PENNSTATE1 8 5 5
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 2
AERSP 407 and 504
Goals:To introduce and study key concepts related to aerodynamic loads, vehicle performance, basic rotor dynamics, and control of helicopters and tilt-rotor aircraft.
Time: Monday, Wednesday, Friday: 1:25-2:15pm
Place:151 Willard Building
Instructor:Dr. Kenneth S. Brentner233 D Hammond BuildingTel: (814) 865-6433Email: [email protected]
Office Hours: Monday and Wednesday 10:30-11:30am; by appointment; I also have an open door policy.
2
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 3
Reference Materials
Textbook:Principles of Helicopter Aerodynamics,
J. Gordon Leishman
I will be basing lecture note primarilyon this book.
Other Good References:Aerodynamics of V/STOL Flight, B. W. McCormick, Jr.Helicopter Theory, W. JohnsonRotary-Wing Aerodynamics, W. Z. Stepniewski and C. N. KeysAerodynamics of the Helicopter, A. Gessow and G. C. Meyers
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 4
Outline
1. Introduction (also read Chapter 1)2. Fundamentals of Rotor Aerodynamics (Chapter 2)3. Blade Element Analysis (Chapter 3)4. Blade Motion and Rotor Control (Chapter 4)5. Basic Helicopter Performance (Chapter 5)6. Conceptual Design of Helicopters (first part of Chapter 6)7. Introduction to Unsteady Aerodynamics, Dynamic Stall,
and Rotor Wakes – time permitting (portions of Chapters 7-10)
This is my first time teaching this course, so I don’t have dates for when we will cover each of the sections.
3
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 5
Grading – AERSP 407
Homework and computer assignments – 35%Approximately 7-8 assignments
Mid-term exam20% in class10% take-home tentatively Oct 21, 2005
Final exam - 35%Term paper - extra credit
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 6
Grading – AERSP 504
Homework and computer assignments – 20%Mid-term exam
20% in class10% take-hometentatively Oct 21, 2005
Final exam – 35%Term paper and presentation – 15%
Topic due Sept. 30Outline due Oct. 28Paper due Nov 23Presentations – sometime during last two weeks of class.
4
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 7
Academic Integrity
Faculty Senate Rule 49-20 states, in part, "Academic integrity is the pursuit of scholarly activity free from fraud and deception and is an educational objective of this institution."
Faculty are required to clarify the application of this rule to each course:
You are encouraged to study together and to discuss the homework assignments, but the work that you submit for grading must be your own.
Acts of academic dishonesty will result in either a grade of zero for an assignment, or an F for the course.
If you have any questions about this, please feel free to talk to me first – this will avoid any problems.
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 8
About Your Instructor:Kenneth S. Brentner
EducationBS Aeronautics and Astronautics, Purdue University – 1983MS Aerodynamics, The George Washington University – 1987Ph.D. Acoustics, University of Cambridge (UK) – 1991 (J.E. Ffowcs Williams, advisor)
Experience(1983 – 2000) Senior Research Engineer at NASA Langley Research Center
Rotorcraft AcousticsComputational AeroacousticsAuthor of WOPWOP rotorcraft noise prediction program
(2000 – present) Associate Professor at The Pennsylvania State University, Department of Aerospace EngineeringPersonal
5
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 9
Today’s Lecture
Introduction to CourseAdministrationMotivation
Introduction to HelicopterLay ground work for Helicopter Aerodynamics
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 10
What is a Helicopter?
Leishman“Helicopters are highly capable and useful rotating-wing
vehicles that have a variety of civilian and military applications. Their usefulness lies in their unique ability to take off and land vertically, to hover stationary to the ground,and to fly forward, backwards, or sideways. These unique flying qualities, however, come at a price, including complex aerodynamic problems, significant vibrations, high levels of noise, and relatively large power requirements compared to fixed-wing aircraft.”
Unique features:Rotating-wing vehiclesAbility to hoverLand and take off verticallyFly forward, backward, and sideways
Helicopters are closely related to autogiros and tiltrotors
6
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 11
Introduction and Motivation
A unique aspect of a helicopter is its ability to hover.The ability to hover is a very useful attribute
Example: A hummingbird is able to feed on the nectar in flowers by hovering for several seconds at a time.
Photo: Luiz Claudio Marigo
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 12
Introduction:Helicopters at Work
Helicopters perform a wide range of missions that benefit from this unique capability (hover or vertical lift)
Scheduled Passenger Service
Executive Transport
7
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 13
Introduction:Helicopters at Work
source: www.hmc.psu.edu/lifelion
Medical evacuation
source: www.hmc.psu.edu/lifelion
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 14
Introduction:Helicopters at Work
source: helispot.comPacific Rotors Magazine
Aerial fire fightingAerial Logging
8
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 15
Introduction:Helicopters at Work
Agricultural: crop spraying
Heavy Lift (tiltrotor in helicopter mode)
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 16
Introduction:Helicopters at Work
Boeing AH-64
Military Helicopters
9
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 17
Comparison of Fixed-Wing Aircraft and Helicopters
Fixed Wing AircraftWings produce lift and roll controlEngines produce thrustTail – primarily for directional and pitch control
Primary functions and controls are decoupled
HelicopterRotor
Produces liftProduces thrustProduces directional control
AND – unbalanced torque!Lift, Thrust, and Control are all
coupled in a helicopter
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 18
Unique Helicopter Problems1. Rotor Torque2. Unequal Lift3. Higher Power Requirements
More power required than a F/W aircraft at any forward velocityTurbine engines; composites; improved rotor airfoils all helped
4. ControlTilting of thrust vector (mechanically difficult)
Swashplate and cyclic pitchCross coupling of motions (pitch, roll, yaw, etc.)
5. Structural Weight6. Vibration and Dynamics Issues7. Interactional Aerodynamics8. Costs and Complexity
Direct Operating Costs (DOC) of helicopter is significantly higher than fixed-wing aircraftMaintenance hours / flight hour also higher
10
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 19
Rotor Torque Control
Ways of countering the Reactive Torque
Other possibilities: Tip jets, tip mounted engines
Question: Why do each of these methods work?What are the likely advantages and disadvantages of each?
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 20
Main Rotor - Tail Rotor Configuration
11
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 21
Tandem Rotors (Chinook)
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 22
Coaxial Rotors (Kamov KA-52)
12
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 23
NOTAR Helicopter
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 24
NOTAR Concept
13
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 25
Tilt Rotor (BA 609)
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 26
Unequal Lift Distribution
Ref: Principles of Helicopter Aerodynamics, J. Gordon Leishman
tipV R= Ω
tipV R V∞= Ω +
tipV R V∞= Ω −
Lift ~ V2
14
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 27
High-Speed Forward Flight Limitations
As the forward speed increases, advancing side experiences shock effects, retreating side stalls. This limits thrust available.Vibrations go up, because of the increased dynamic pressure, and increased harmonic content.Shock noise goes up.Fuselage drag increases, and parasite power consumption goes up as V3.We need to understand and accurately predict the air loads in high speed forward flight.
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 28
Interactional Aerodynamics
The aerodynamic environment for a helicopter rotor is complex – rotor aerodynamics important for:
PerformanceStructural AnalysisDynamicsFlight DynamicsAcoustics…
This is my area of research
15
PENNSTATE1 8 5 5
Kenneth S. Brentner, Dept. of Aerospace Engineering 29
Next Time
Read Chapter 1We will start on Momentum Theory for a hovering rotor