An airplane's center of gravity is shifted from mid-range toward the forward CG limit without changing the airplane's gross weight. How is the airplane's stall speed most likely affected, and why?
- AStall speed decreases because a forward CG increases static longitudinal stability
- BStall speed decreases because a forward CG reduces the airplane's induced drag
- CStall speed increases slightly because the wing must produce additional lift to offset increased tail download
- DStall speed remains exactly unchanged since total weight is unaffected by CG position
Show answer & explanationAnswer & explanation
Correct answer: C. Stall speed increases slightly because the wing must produce additional lift to offset increased tail download
With a forward CG, the horizontal stabilizer must generate more download to balance the airplane in pitch, which the wing must support in addition to the airplane's actual weight. This effectively increases the wing's lift requirement, meaning the wing must reach a slightly higher angle of attack (or the airplane a slightly higher speed) to stall — resulting in a small increase in stall speed compared to a more aft CG at the same gross weight.
Why the other options are wrong
- A. Increased static stability from a forward CG is real, but it does not by itself cause stall speed to decrease.
- B. Forward CG increases trim drag/tail download; it does not reduce induced drag or lower stall speed.
- D. While gross weight is unchanged, the effective load on the wing changes due to tail download, so stall speed is affected.
CG Position and Stall Speed
A forward CG requires more tail download to balance the airplane, increasing the effective load the wing must support and slightly increasing stall speed compared to an aft CG at the same gross weight.
- Forward CG → more tail-down force needed for pitch balance
- Wing must lift weight PLUS tail download
- Slightly higher stall speed and slightly better stability result from forward CG
Memory trick: Nose-heavy needs more tail push down, so the wing works a little harder to stall.