Lect 003 Introduction to Aerodynamics

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2Wednesday, July 30, 2014 Elements of Aeronautics

Elements of Aeronautics

Basics of basics

How to be happy in EOA?

Try to attend all the classes

Take notes on the class, maintain a notebook

Just read it every evening for 30 minutes

Own 2 books on Basics (Low Price Editions

available)

Do the Assignments and Cycle Tests properly...


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3. Introduction to Aerodynamics

Aerodynamic forces on aircraft

Classification of NACA Aerofoils, Aspect ratio, Wing

Loading, Mach NumberCentre of Pressure , Aerodynamic Centre

Aerofoil characteristics Life and Drag curves


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3.1. Aerodynamic Forces on Aircraft

The science of the action of air on an object, and with

the motion of air on other gases. Aerodynamics deals

with the production of lift by the aircraft, the relative

wind, and the atmosphere.


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5Elements of Aeronautics



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Four forces on Aircraft



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Thrust is the forward force produced by the power plant

/propeller. It opposes or overcomes the force of drag.

Drag is a rearward, retarding force, and is caused by disruption

of airflow by the wing, fuselage, and other protruding objects.

Weight is the combined load of the airplane itself, the crew, the

fuel, and the cargo or baggage. Weight pulls the airplane

downward because of the force of gravity.

Lift opposes the downward force of weight, is produced by the

dynamic effect of the air acting on the wing, and acts

perpendicular to the flight path through the wings center of lift.

Four forces on Aircraft




Reference axes system in Aircraft




Reference axes




Pitching moment

3.1. Aerodynamic Moments on Aircraft



Rolling moment




Yawing moment




3.2. Geometric Parameter of Wing


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Mean Chamber Line:Set of points halfway between upper and lower surfaces

Measured perpendicular to mean chamber line itself

Leading Edge:Most forward point of mean chamber line

Trailing Edge:Most reward point of mean chamber line

Chord Line:Straight line connecting the leading and trailing edges

Chord, c:Distance along the chord line from leading to trailing edge

Chamber:Maximum distance between mean chamber line and chord line

Measured perpendicular to chord line



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3 2 eometr c Parameter

o W ng


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3.2. eometr c Parameter o W ng


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Dihedral Angle: The positive acute angle between the lateral axis of

an airplane and a line through the center of a wing or horizontal

stabilizer. Dihedral contributes to the lateral stability of an airplane.


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3.3. Classification of NACA Aerofoil

First digitspecifies maximum camber in percentage of chord

Second digitindicates position of maximum camber in tenths of chord

Last two digitsprovide maximum thickness of airfoil in percentage of chord

Example: NACA 2415 Airfoil has maximum thickness of 15%

of chord (0.15c)

Camber of 2%(0.02c) located 40%

back from airfoil leading edge (0.4c)

NACA 2415

AOA 2


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AOA = 2

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AOA 3


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AOA = 3


AOA 6


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AOA = 6


AOA 9


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AOA = 9


AOA 12


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AOA = 12


AOA 20


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AOA = 20


AOA 60


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AOA = 60


AOA 90


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AOA = 90



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Lift coefficient (or lift) linearvariation with angle of attack, a

Cambered airfoils have

positive lift when a = 0

Symmetric airfoils have

zero lift when a =0

At high enough angle of attack,

the performance of the airfoil

rapidly degrades stall

Cambered airfoil has

lift at a=0

At negative aairfoil

will have zero lift


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3 2 Geometric Parameter of Wing


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Pressure Distribution on Aerofoil


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3 2 G i P f Wi


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3 2 G i P f Wi


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3 2 G i P f Wi


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3 2 G t i P t f Wi


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Lect 003 Introduction to Aerodynamics

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