Question

A Jet transport aircraft is flying with crew load of 175kg, payload of 1400kg and fuel weight of 500kg. Find out Fuel to empty weight fraction, if design take-off gross weight of the aircraft is 5600lb.

(a) 1.076

(b) 0.1831

(c) 0.196

(d) 0.1418

I got this question during an interview.

Question is from Conceptual Sketch Sizing topic in portion Conceptual Sketch Sizing of Aircraft Design

Answer 1

The correct answer is (a) 1.076

The explanation: Given,

Design take-off gross weight, W0 = 5600lb = 2539.6825kg

Crew load = 175kg

Payload weight = 1400kg, fuel weight = 500kg

Now the design take – off gross weight is given by,

W0 = Wcrew + Wpayload + Wfuel + Wempty

2539.682 = 175+ 1400 + 500 + Wempty

So, Wempty = 464.682kg

Fuel weight fraction = Wfuel / W0

Empty weight fraction = Wempty / W0

Now fuel to empty weight fraction = Wfuel / Wempty = 500/464.682 = 1.076.