Question

What is the working principle of ‘fuel-fraction’ method?

(a) Division of mission profile into number of phases and finding individual phase fuel fraction

(b) Division of mission profile into 3 phases only

(c) Calculating fuel fraction for each stage

(d) Assuming any value for fuel fraction

This question was addressed to me in an interview for internship.

My question is taken from Conceptual Sketch Sizing in chapter Conceptual Sketch Sizing of Aircraft Design

Answer 1

Correct answer is (a) Division of mission profile into number of phases and finding individual phase fuel fraction

The best I can explain: The fuel fraction method is mostly used method for fuel weight fraction. This is very simple method in which we divide whole mission profile into number of mission phases. After that we calculate individual mission segment weight fraction. And based on which we determine approximated fuel weight.