What risks are associated with an aft center of gravity and how do performance characteristics change?

What risks are associated with an aft center of gravity and how do performance characteristics change?

• A. Aft CG increases stability and reduces stall tendency
• B. Aft CG reduces stall tendency and improves longitudinal control
• C. Aft CG has no effect on stability
• D. Aft CG reduces stability, increases stall tendency, and can reduce longitudinal control; may increase maneuverability but worsen stall behavior

Answer: (D)

An aft center of gravity shifts the balance toward the tail, reducing static longitudinal stability. With the CG behind the neutral point, the nose tends to stay where it is or even pitch up more easily after a disturbance, so the airplane is less stable in pitch and the restoring moment is weaker. This makes the aircraft more sensitive to control inputs and disturbances, and can make maintaining a steady pitch harder. Because the wing’s angle of attack can reach the critical value more readily with an aft CG, stall is more likely and can be less forgiving—often more abrupt. In a stall, airflow over the tail and around the elevator is altered, which reduces control effectiveness and makes pitch recovery tougher. At the same time, the airplane can feel more maneuverable or responsive to inputs due to the lowered stability, but that comes with reduced control margins and less predictable pitch behavior. So, an aft CG brings reduced stability, a higher tendency to stall, and potential loss of reliable longitudinal control; it can offer greater maneuverability in some regimes, but at the cost of worse stall characteristics and control reliability.

An aft center of gravity shifts the balance toward the tail, reducing static longitudinal stability. With the CG behind the neutral point, the nose tends to stay where it is or even pitch up more easily after a disturbance, so the airplane is less stable in pitch and the restoring moment is weaker. This makes the aircraft more sensitive to control inputs and disturbances, and can make maintaining a steady pitch harder.

Because the wing’s angle of attack can reach the critical value more readily with an aft CG, stall is more likely and can be less forgiving—often more abrupt. In a stall, airflow over the tail and around the elevator is altered, which reduces control effectiveness and makes pitch recovery tougher. At the same time, the airplane can feel more maneuverable or responsive to inputs due to the lowered stability, but that comes with reduced control margins and less predictable pitch behavior.

So, an aft CG brings reduced stability, a higher tendency to stall, and potential loss of reliable longitudinal control; it can offer greater maneuverability in some regimes, but at the cost of worse stall characteristics and control reliability.