Question

Which of the following is correct?

(a) Typically, higher bypass ratio will give higher efficiency

(b) Higher bypass ratio always decreases efficiency

(c) Lift is equal to weight always

(d) Thrust required is the same as thrust available

This question was posed to me by my college professor while I was bunking the class.

My question is from Propulsion in chapter Propulsion of Aircraft Design

Answer 1

Right choice is (a) Typically, higher bypass ratio will give higher efficiency

To explain I would say: We can improve engine efficiency by using high bypass ratio. Lift is not always same as weight. Lift is same as weight during cruise segment. Thrust required and thrust available are different from each other. Thrust available is actual thrust produced by engine. Thrust required is the amount of thrust required to oppose the drag.