FAA Private Pilot Helicopter (PRH)Helicopter Aerodynamics and SystemsMedium
A helicopter pilot enters a coordinated 60-degree bank turn while maintaining altitude. Using the load factor formula (load factor = 1 / cosine of bank angle), what approximate load factor is the helicopter experiencing?
- A3.0 G
- B2.0 G
- C2.5 G
- D1.5 G
Show answer & explanationAnswer & explanation
Correct answer: B. 2.0 G
Load factor = 1 / cos(60°) = 1 / 0.5 = 2.0 G. In a level, coordinated 60-degree bank turn, the helicopter and rotor system experience twice the force of gravity, which increases power required and can lead to rotor RPM decay if not managed.
Why the other options are wrong
- A. 3.0 G would require a bank angle of about 70.5 degrees.
- C. 2.5 G would require a steeper bank angle of about 66 degrees.
- D. 1.5 G would correspond to a shallower bank angle (about 48 degrees), not 60 degrees.
Load Factor in a Bank
The ratio of total lift required to aircraft weight during a coordinated level turn, calculated as 1 divided by the cosine of the bank angle.
- 60-degree bank produces 2.0 G load factor
- Increased load factor increases power required and stall/blade-stall risk
- Steep turns can cause rotor RPM decay if power/collective is not adjusted
Memory trick: 60 degrees doubles your weight—2 G's on the gauge