Which statement about center of gravity location is correct?

• A. Forward CG decreases stability; aft CG increases elevator effectiveness
• B. CG location has no effect on stability
• C. Forward CG increases longitudinal stability and controllability margins but reduces elevator effectiveness; aft CG improves maneuverability but reduces stability and stall margin
• D. CG only affects fuel efficiency

Answer: (C)

Center of gravity position dictates how firmly the aircraft behaves in pitch and how much elevator is needed to change that pitch. When the CG is forward, the airplane has a stronger nose-down restoring tendency after any disturbance, giving greater longitudinal stability. That same forward placement means the tail must work harder to balance the forward weight, so for a given elevator deflection the pitching moment about the center of gravity is smaller, making elevator effectiveness (the ability of the elevator to produce a pitch change) reduced. In contrast, moving the CG toward the rear decreases the restoring forces, so maneuverability and responsiveness improve, but stability and stall margins erode. So the statement that a forward CG increases longitudinal stability and control margins while reducing elevator effectiveness, and that an aft CG improves maneuverability but reduces stability and stall margin, accurately describes the relationships.