If the center of gravity is positioned at the neutral point, what is the resulting stability condition?

• A. The aircraft is statically unstable.
• B. The aircraft is statically stable.
• C. The aircraft experiences unstable lift characteristics but not stability.
• D. The aircraft is neutrally stable.

Answer: (D)

Static stability hinges on whether a small pitch disturbance creates a restoring moment. The neutral point marks the aft limit for stability: with the CG ahead of it, you get positive stability and the airplane tends to return to its original attitude; behind it, the disturbance tends to grow, making the aircraft unstable. If the center of gravity is right at the neutral point, there’s no net restoring or overturning moment for small changes in angle of attack. That means the aircraft is neutrally stable: a slight disturbance leaves the aircraft in a new attitude rather than returning to the original or diverging. The static stability margin in this situation is zero.