How does weight distribution forward versus aft center of gravity affect stability and elevator effectiveness?

• A. Forward CG increases longitudinal stability and elevator effectiveness but raises stall speed and may reduce pitch authority; aft CG decreases stability and elevator effectiveness and can make stalls more abrupt.
• B. Aft CG decreases stability and elevator effectiveness and can make stalls more abrupt.
• C. Forward CG increases stability and elevator effectiveness but raises stall speed.
• D. CG position has no effect on stability or elevator effectiveness.

Answer: (C)

Shifting weight forward makes the airplane more stable in pitch. With the CG toward the nose, the aircraft resists pitch changes and tends to return to the trimmed attitude after a disturbance, giving greater longitudinal stability.

That same forward shift also makes the elevator more effective in producing pitch changes. The tail has to generate a larger stabilizing force to balance the nose-down tendency, and for a given elevator deflection this tail force translates into a stronger pitching moment about the center of gravity. In practical terms, you get a more pronounced pitch response from the same elevator input, improving elevator effectiveness.

The trade-off is stall speed. A forward CG means the wing must generate more lift to keep the airplane level, so it flies at a higher angle of attack before stalling, raising the stall speed.

So, forward CG brings increased stability and stronger elevator response, at the cost of higher stall speed.