Flight Mechanics Preliminaries

1
Flight Mechanics - Preliminaries

• K Sudhakar H Arya A
  Isaacs
• Centre for Aerospace Systems Design Engineering
• Department of Aerospace Engineering
• IIT Bombay, Mumbai 400076

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It Comes in All Shapes
What makes them fly?
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Contents

• Principles of Flight
• Airfoil
• Wing
• Wing Horizontal tail

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Why Airfoil ?
Drag
Airfoil Shape that offers very low drag
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Lift, Drag Moment

• - Angle of Attack

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Moment
L1 L M1 M - L x1
(dM1/d?) (dM/d?) (dL/d?) x1
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Lift Drag
More than that for airfoil

• - Angle of Attack
• Lift 0.5 ? V2 C a?
• Moment 0.5 ? V2 C2 d d 0

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Lift Drag

• - Angle of Attack
• Lift 0.5 ? V2 C a?
• Moment 0.5 ? V2 C2 d d gt 0

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Lift Drag
Lift
?
Drag
Moment (Pitching)
V

• - Angle of Attack
• Lift 0.5 ? V2 C a?
• Moment 0.5 ? V2 C2 d d lt 0

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Airfoil
Moment is about 0.25C
Moment does not change with ? Lift increases with
?
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Airfoil
Moment is about 0.25C
Moment does not change with ? Lift increases with
?
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Equilibrium Stability
Unstable
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Aerodynamic Center
Point about which Moment does not change with
? 0.25 C for an Airfoil. CG w.r.t. Aerodynamic
Center ? Stability
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Airfoil, Flat Plate Or Strip of Paper
L W L X Mo 0 X - Mo/L
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Airfoil, Flat Plate Or Strip of Paper

• How to make a strip of paper fly?
• AR is large ? Like a flat plate airfoil
• h 0 ? M0 0 ? X 0
• X 0 ? Neutral
• For stability
• h lt 0 ? M0 gt 0 ? X lt 0
• X lt 0 ? Stable

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Lets Fly a Strip of Paper!
Stable
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Lets Fly a Strip of Paper!
Stable
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Lets Fly a Strip of Paper!
Stable
Hinge line of elevator
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Wing
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Wing
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Wing
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Lets Fly a Wing!
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Wing Horizontal Tail (No Fuselage)
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Vertical Tail?
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Vertical Tail? Dihedral?
?
Lets move on
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Control Surfaces
Ailerons
Elevators
Rudder
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Elevators - Pitch
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Ailerons - Roll
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Rudder - Yaw
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Thank You