Dynamic stability is defined as which property?

• A. The property that when disturbed from straight-and-level flight, forces moment restore original condition
• B. The ability to perform dynamic aerobatics
• C. The stability of an aircraft's structural frame
• D. The aerodynamic coefficient of drag

Answer: (C)

Dynamic stability describes how an aircraft responds over time after it’s disturbed from straight-and-level flight. If the aerodynamics produce restoring forces and moments that bring the aircraft back toward its original flight condition, and any resulting motion damps out rather than grows, the aircraft has positive dynamic stability. This concept focuses on the time-dependent behavior and damping of the aircraft’s motion, not on instantaneous shape, aerobatic capability, structural integrity, or drag properties. The option that captures this idea states that disturbances are countered by forces and moments that restore the original condition, which is why it best describes dynamic stability. The other ideas refer to performance traits or structural or drag aspects that don’t describe how the aircraft behaves over time after a disturbance.