Question

What is the velocity of maximum specific endurance of the engine when the maximum air speed is 400m/s and the exponential value is 0.2?

(a) 350.43

(b) 490.34

(c) 494.37

(d) 380.43

This question was posed to me in an interview.

This intriguing question originated from Cruising Performance in chapter Cruising Performance of Aircraft Performance

Answer 1

The correct answer is (d) 380.43

For explanation: The answer is 380.43.

Given n=0.2, Vmd=400m/s. From the formula \(\big[\frac{2-n}{2+n}\big]^{\frac{1}{4}}\)Vmd. On substituting the values we get \(\big[\frac{2-0.2}{2+0.2}]^{\frac{1}{4}}\)*400=380.43.