FAA Sport Pilot Airplane (SPA)Aircraft Performance and SystemsMedium
A pilot loads the airplane so the center of gravity is near the aft limit rather than the forward limit. Compared to a forward CG loading, which effect should the pilot expect?
- ANo change in stall speed but increased stability
- BHigher stall speed and increased longitudinal stability
- CHigher stall speed and decreased longitudinal stability
- DLower stall speed and decreased longitudinal stability
Show answer & explanationAnswer & explanation
Correct answer: D. Lower stall speed and decreased longitudinal stability
An aft CG reduces the download the tail must produce to balance the airplane, effectively reducing the wing's required lift and lowering stall speed slightly, but it also reduces the airplane's natural nose-down restoring tendency, decreasing longitudinal stability.
Why the other options are wrong
- A. Stall speed and stability both change with CG position, not remain constant.
- B. Forward CG, not aft, increases stall speed and stability.
- C. Aft CG does not raise stall speed; it lowers it slightly.
CG Position Effects
The location of the center of gravity affects stall speed, stability, and controllability; aft CG reduces stability while forward CG increases stall speed and stability.
- Aft CG: lower stall speed, less stable, easier to stall into a spin
- Forward CG: higher stall speed, more stable, harder elevator control in flare
- CG must remain within approved limits for safe flight
Memory trick: Aft CG: light on stall, loose on stability.