Question

If a propeller has bhp of 700 and diameter as 1.2 ft. and rotating with 20 rps then, determine power coefficient. Consider sea level density.

(a) 15.8

(b) 1.8

(c) 30.2

(d) 40

I have been asked this question in an internship interview.

This interesting question is from Propulsion topic in portion Propulsion of Aircraft Design

Answer 1

The correct choice is (a) 15.8

The explanation is: Power coefficient = 550*bhp / (density*diameter^5*rps^3)

= 550*700 / (1.225*1.2^5*20^3) = 15.8.