FAA Sport Pilot Airplane (SPA)Aircraft Performance and SystemsHard
An airplane has a stalling speed of 50 knots in straight-and-level, unaccelerated flight. What is its approximate stalling speed while in a coordinated, level 60° bank turn?
- A71 knots
- B50 knots
- C61 knots
- D100 knots
Show answer & explanationAnswer & explanation
Correct answer: A. 71 knots
A 60° bank turn produces a load factor of 2 G. Stall speed increases by the square root of the load factor: new stall speed = 50 × √2 = 50 × 1.41 ≈ 71 knots.
Why the other options are wrong
- B. Incorrect — this ignores the load factor increase caused by banking.
- C. Incorrect — this understates the actual increase from the 2G load factor.
- D. Incorrect — this would require a load factor of 4G, not 2G.
Load Factor and Stall Speed in Turns
As bank angle increases in a level turn, load factor increases, and stall speed increases proportionally to the square root of the load factor.
- 30° bank = 1.15G load factor
- 45° bank = 1.41G load factor
- 60° bank = 2G load factor
- Stall speed increase = original stall speed × √(load factor)
Memory trick: 60° bank doubles your weight and raises your stall speed by root-2