FAA Part 107 Remote Pilot (UAG)Loading and PerformanceMedium
A technician replaces a fixed-wing sUAS's standard battery with a significantly heavier extended-range battery, without changing the wing area. How will this affect the aircraft's stall speed?
- AStall speed will remain the same since stall speed depends only on airfoil shape
- BStall speed will increase because the added weight increases wing loading, requiring more airspeed to generate sufficient lift
- CStall speed will decrease because greater weight increases the aircraft's momentum through the air
- DStall speed will decrease because the added weight lowers the wing loading
Show answer & explanationAnswer & explanation
Correct answer: B. Stall speed will increase because the added weight increases wing loading, requiring more airspeed to generate sufficient lift
Wing loading is the aircraft's weight divided by wing area. Increasing weight without changing wing area raises wing loading, meaning the wings must produce more lift, which requires higher airspeed to reach the critical angle of attack — resulting in a higher stall speed.
Why the other options are wrong
- A. Stall speed is directly influenced by weight and wing loading, not just airfoil shape.
- C. Increased momentum does not lower stall speed; it is unrelated to the stall speed relationship.
- D. Added weight raises wing loading, it does not lower it.
Wing Loading and Stall Speed
Wing loading is weight divided by wing area; higher wing loading requires higher airspeed to generate the lift needed to avoid a stall.
- Wing loading = weight ÷ wing area
- Higher weight (same wing area) increases wing loading and stall speed
- Stall occurs at critical angle of attack regardless of speed, but higher loading requires higher speed to sustain lift
Memory trick: Heavier plane, same wings — it must fly faster to stay up.