FAA Commercial Pilot Airplane (CAX)Aerodynamics and PerformanceHard
A pilot is performing a rapid descent at a high rate of speed. During the recovery, the pilot pulls back on the control stick, imposing a load factor of +4.0G. If the airplane's unaccelerated (1G) stall speed is 60 KCAS, what is the accelerated stall speed in this maneuver?
- A60 KCAS
- B90 KCAS
- C120 KCAS
- D240 KCAS
Show answer & explanationAnswer & explanation
Correct answer: C. 120 KCAS
The accelerated stall speed is calculated by multiplying the unaccelerated stall speed by the square root of the load factor. So, for a 4.0G load factor: Accelerated Stall Speed = 60 KCAS * sqrt(4.0) = 60 KCAS * 2 = 120 KCAS.
Why the other options are wrong
- A. Incorrect, this is the 1G stall speed.
- B. Incorrect, likely a miscalculation (e.g., 60 * 1.5).
- D. Incorrect, a significant overestimation.
Accelerated Stall Speed
The stall speed an airplane exhibits when subjected to a load factor greater than 1G. It increases in proportion to the square root of the load factor.
- Occurs during accelerated maneuvers (e.g., steep turns, pull-ups).
- Formula: Vs_accelerated = Vs_1G * sqrt(Load Factor).
- Higher load factor means higher stall speed.
- Stalls can occur at any airspeed if the critical angle of attack is exceeded.
Memory trick: More Gs means your stall speed grows, like a weightlifter's muscle.