Aerodynamic Center - Role of Aerodynamic Center in Aircraft Stability

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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