FAA Private Pilot Helicopter (PRH)Performance and LimitationsHard
A helicopter weighing 2,000 pounds enters and maintains a coordinated, level 60° angle-of-bank turn. Using the load factor formula (n = 1 / cos(bank angle)), what approximate total lift must the rotor system produce to maintain altitude?
- A2,800 pounds
- B2,000 pounds
- C4,000 pounds
- D3,000 pounds
Show answer & explanationAnswer & explanation
Correct answer: C. 4,000 pounds
Load factor n = 1/cos(60°) = 1/0.5 = 2. Total lift required equals load factor multiplied by weight: 2 × 2,000 lb = 4,000 lb. This doubling of required lift substantially increases power demand and reduces the helicopter's performance margin.
Why the other options are wrong
- A. 2,800 lb does not correspond to the correct load factor calculation for a 60° bank.
- B. 2,000 lb would only apply in straight-and-level flight with no bank (1G).
- D. 3,000 lb corresponds to a load factor of 1.5, not the correct 2G for a 60° bank.
Load Factor Lift Calculation
In a level turn, required lift equals load factor (n = 1/cos bank angle) multiplied by aircraft weight; steep banks dramatically increase the lift and power demand.
- n = 1/cos(bank angle)
- At 60° bank, n = 2 (double weight in lift)
- Lift required = n × aircraft weight
Memory trick: 60° bank doubles your weight in the rotor's eyes—2,000 becomes 4,000