Static & Dynamic Stability

Static Stability

The initial tendency of an aircraft to return to its original equilibrium position after being disturbed.

• Positive: Initial tendency to return to the original position.
• Neutral: Tendency to remain in the new displaced position.
• Negative: Initial tendency to move further away from the original position (Divergence).

Dynamic Stability

The behavior of the aircraft over time after being disturbed. It concerns the damping of oscillations.

• Positive: Oscillations decrease in amplitude over time (Damped).
• Neutral: Oscillations remain constant in amplitude (Undamped).
• Negative: Oscillations increase in amplitude over time (Divergent).

Relationship

• An aircraft can be statically stable but dynamically unstable (it tries to return, but overshoots more each time).
• However, for an aircraft to be dynamically stable, it must be statically stable.