Question

Find the acceptable value of ram drag if Turbojet is designed to provide net thrust of 88% of gross thrust. Engine gross thrust is 12.5KN.

(a) 1.5KN

(b) 2500

(c) 23456

(d) 4325

I have been asked this question at a job interview.

My question is based upon Propulsion in chapter Propulsion of Aircraft Design

Answer 1

The correct answer is (a) 1.5KN

For explanation: Ram drag = Gross Thrust – net Thrust = 12.5 – 0.88*12.5 = 1.5KN.