Question

An Aircraft has gross weight of 10000lb. At the end of the mission segment it has weight fraction as 0.985. Determine fuel consumed for this mission.

(a) 150lb

(b) 150kg

(c) 60kg

(d) 60lb

The question was asked in an online interview.

This intriguing question originated from Conceptual Sketch Sizing in portion Conceptual Sketch Sizing of Aircraft Design

Answer 1

The correct choice is (a) 150lb

For explanation I would say: Given,

Aircraft gross weight W0 = 10000lb

Fuel weight fraction at the end of mission = Wx/W0 = 0.985

Here, there is no provision of reserved fuel is mentioned. So, we are neglecting reserve fuel fraction.

Now, from fuel fraction method,

Used fuel weight fraction is Wf / W0 = 1 – (Wx / W0)

= 1 – 0.985 = 0.015

Hence, fuel consumed during this mission = Wf = W0 * 0.015 = 10000 * 0.015 = 150lb.