Question

A prop-driven aircraft having fuel weight of 650kg. Now, aircraft is taxing on runway, after which it has fuel fraction of 0.975. Determine fuel used during taxing of aircraft, if W0 = 5000kg.

(a) 225kg

(b) 125kg

(c) 221kg

(d) 125.65lb

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

This intriguing question comes from Conceptual Sketch Sizing in division Conceptual Sketch Sizing of Aircraft Design

Answer 1

The correct answer is (b) 125kg

For explanation I would say: Given,

Aircraft take-off gross weight W0 = 5000kg,

Fuel weight fraction after taxi = Wtaxi/W0 = 0.975

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 – (Wtaxi/W0)

= 1 – 0.975 = 0.025

Hence, fuel used during taxing mission = Wf = W0 * 0.025 = 125kg.