If the center of gravity is aft of the aft limit, what effect does this have on controllability?

If the center of gravity is aft of the aft limit, what effect does this have on controllability?

• A. Increased maneuverability
• B. Stall and spin recovery may be difficult or impossible
• C. No effect
• D. Decreases stall speed

Answer: (B)

Pushing the center of gravity behind the aft limit reduces longitudinal stability and control effectiveness. When the CG is far aft, the airplane has less restoring pitch moment, so disturbances can cause the nose to pitch up and the aircraft to become more difficult to hold level. The tail-down force needed for trim and stability is reduced, and elevator authority becomes less effective as the wing approaches stall. That combination makes stall and spin recovery much more difficult, and in some cases the spin may be unrecoverable. The idea of increased maneuverability is not correct here—aft CG actually makes the airplane harder to control. Stall speed is not reliably reduced by moving the CG aft, so that option isn’t supported by how stability and control work in the airplane.

Pushing the center of gravity behind the aft limit reduces longitudinal stability and control effectiveness. When the CG is far aft, the airplane has less restoring pitch moment, so disturbances can cause the nose to pitch up and the aircraft to become more difficult to hold level. The tail-down force needed for trim and stability is reduced, and elevator authority becomes less effective as the wing approaches stall. That combination makes stall and spin recovery much more difficult, and in some cases the spin may be unrecoverable. The idea of increased maneuverability is not correct here—aft CG actually makes the airplane harder to control. Stall speed is not reliably reduced by moving the CG aft, so that option isn’t supported by how stability and control work in the airplane.