FAA Flight Instructor Airplane (FIA)Performance, Weight and BalanceHard
At a given altitude, an airplane's engine produces 150 hp of power available while 110 hp is required for level flight at that altitude and weight. If the airplane weighs 2,750 lb, what is the theoretical maximum rate of climb?
- A360 fpm
- B550 fpm
- C480 fpm
- D600 fpm
Show answer & explanationAnswer & explanation
Correct answer: C. 480 fpm
Excess power = 150 − 110 = 40 hp. ROC (fpm) = 33,000 × excess hp ÷ weight = 33,000 × 40 ÷ 2,750 = 480 fpm.
Why the other options are wrong
- A. Uses an incorrect excess power value.
- B. Overstates the result by an incorrect weight substitution.
- D. Rounds incorrectly and ignores the actual weight division.
Excess Power and Rate of Climb
Rate of climb depends on the excess power available beyond what is required for level flight; ROC (fpm) = 33,000 × excess hp ÷ weight (lb).
- Excess power = power available − power required
- ROC (fpm) = 33,000 × excess hp ÷ weight
- Zero excess power occurs at absolute ceiling
- More excess power or lighter weight increases climb rate
Memory trick: 'Extra power lifts you faster, extra weight drags you down.'