Role of Aerodynamic Center in Aircraft Stability
For longitudinal static stability: and
For directional static stability: and
Where:
For A Force Acting Away at the Aerodynamic Center, which is away from the reference point:
Which for Small Angles and =, simplifies to:
General Case: From the definition of the AC it follows that
- .
- .
The Static Margin can then be used to quantify the AC:
where:
- = yawing moment coefficient
- = pitching moment coefficient
- = rolling moment coefficient
- = X-force ~= Drag
- = Y-force ~= Side Force
- = Z-force ~= Lift
- ref = reference point (about which moments were taken)
- c = reference length
- S = reference area
- q = dynamic pressure
- = angle of attack
- = sideslip angle
SM = Static Margin
Read more about this topic: Aerodynamic Center
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