Which statement best describes the effect of a rearward center of gravity on stability?

• A. It destabilizes the airplane about the vertical axis.
• B. It has no effect on stability.
• C. It improves stability about the vertical axis.
• D. It only affects wings' lift.

Answer: (C)

Yaw stability is the airplane’s tendency to align with the relative wind around the vertical axis. This stability mainly comes from the tail surfaces behind the center of gravity, which create a restoring moment when the aircraft yaws off course. The strength of that restoring moment depends on the distance from the center of gravity to the tail—the moment arm. If the center of gravity is moved rearward, that distance shortens, so the restoring yaw moment becomes smaller. The result is reduced stability about the vertical axis, making the aircraft more prone to sideslip and uncommanded yaw. This effect concerns yaw behavior and not the primary lift of the wings.