What are the consequences of forward CG versus aft CG on stability and stall characteristics?

• A. Forward CG generally improves stability and increases stall speed; aft CG can reduce stability but may increase cruise performance.
• B. Forward CG reduces stability but increases climb rate.
• C. Aft CG improves stability and increases stall speed.
• D. CG position has no effect on performance.

Answer: (A)

Moving the center of gravity forward makes the airplane more pitch-stable. The weight being ahead of the lift forces creates a stronger restoring moment if the nose pitches up or down, so the aircraft tends to return to level flight more readily. To maintain level flight with a forward CG, the tail must push downward harder to balance, which adds downforce and drag. That extra demand on the wing lift and the reduced elevator authority available to control pitch near the stall means you reach the stall at a higher airspeed. So stability goes up and stall speed goes up as the CG moves forward.

Shifting the CG aft reduces this restoring tendency, so the airplane becomes more pitch-sensitive and less stable. The tail-down force decreases, drag can drop, and cruise performance can improve, but stability and controllability near the stall become more marginal. That’s why the option describing forward CG as improving stability and increasing stall speed, with aft CG reducing stability while offering potential cruise improvements, is the best fit.