The aircraft becomes less stable as the CG is moved rearward. This is because when the CG is moved rearward it causes an increase in the AOA. Which CG location does this describe?

The aircraft becomes less stable as the CG is moved rearward. This is because when the CG is moved rearward it causes an increase in the AOA. Which CG location does this describe?

• A. Aft CG
• B. Fwd CG
• C. Neutral CG
• D. Center of gravity

Answer: (A)

Pitched stability is what’s being tested here. When the center of gravity moves toward the tail, the airplane’s ability to return to its original attitude after a disturbance is reduced. The neutral point is the aerodynamic balance point; if the CG sits behind it, the airplane becomes less stable and a small nose-up disturbance tends to grow rather than damp out. With the CG aft, a disturbance that increases the angle of attack is less effectively countered by the tail forces, so the aircraft tends to hold a higher angle of attack rather than return to the previous attitude. That’s why this situation describes an aft CG.

Pitched stability is what’s being tested here. When the center of gravity moves toward the tail, the airplane’s ability to return to its original attitude after a disturbance is reduced. The neutral point is the aerodynamic balance point; if the CG sits behind it, the airplane becomes less stable and a small nose-up disturbance tends to grow rather than damp out. With the CG aft, a disturbance that increases the angle of attack is less effectively countered by the tail forces, so the aircraft tends to hold a higher angle of attack rather than return to the previous attitude. That’s why this situation describes an aft CG.