Title: Flight Mechanics Preliminaries
1Flight Mechanics - Preliminaries
- Center for Aerospace Systems Design Engineering
- Department of Aerospace Engineering
- IIT Bombay, Mumbai 400076
2Aircraft Come in All Shapes
What makes them fly?
3Contents
- Principles of Flight
- Airfoil
- Wing
- Wing Horizontal tail
- Flight Mechanics?
4Why Airfoil ?
Drag
Airfoil Shape that offers very low drag
5Airfoil Lift, Moment Thickness, Camber
Sign convention
V?
6Lift Moment
Fixed ? V? Some MRF
dL/d? dM/d? are constant over a range of ?
7Watch out ! CP and AC
L1 L M1 M - L x1
(dM1/d?) (dM/d?) (dL/d?) x1
8Lift Moment
Lift 0.5 ? V2 C a ? Moment 0.5 ? V2 C2
d Moment is about 0.25 C
9Flat Plate
More than that for airfoil
- Lift 0.5 ? V2 C a?
- Moment 0.5 ? V2 C2 d d 0
10Lift Moment
- Lift 0.5 ? V2 C a?
- Moment 0.5 ? V2 C2 d d gt 0
11Lift Moment
Lift
?
Drag
Moment (Pitching)
V
- Lift 0.5 ? V2 C a?
- Moment 0.5 ? V2 C2 d d lt 0
12Airfoil / Flat Plate
Moment is about 0.25C
Moment does not change with ? Lift increases with
?
13Airfoil
Moment is about 0.25C
Moment does not change with ? Lift increases with
?
14Equilibrium Stability
Unstable
15Aerodynamic Center
Point about which Moment does not change with
? 0.25 C for an Airfoil. CG w.r.t. Aerodynamic
Center ? Stability
16Flat Plate ? 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
17Lets Fly a Strip of Paper!
Stable
18Lets Fly a Strip of Paper!
Stable
19Lets Fly a Strip of Paper!
Stable
Hinge line of elevator
20Wing
21Wing
22Wing
23Lets Fly a Wing!
24Wing Horizontal Tail (No Fuselage)
25Vertical Tail?
26Vertical Tail? Dihedral?
?
27Flight Mechanics?
Thank You
28Equations of Motion
- Rigid body dynamics
- Aerodynamic forces moments modeled
29Decoupled Equations
30Decoupled Equations
Lo Longitudinal, LD
Lateral-Directional
31http//www.casde.iitb.ac.in sudhakar_at_aero.iitb.ac
.in
Thank You
32Airfoil, Flat Plate Or Strip of Paper
L W L X Mo 0 X - Mo/L
33Control Surfaces
Ailerons
Elevators
Rudder
34Elevators - Pitch
35Ailerons - Roll
36Rudder - Yaw