Question

An aircraft has Crew and payload of 180kg. It has empty weight fraction of 0.48 and fuel weight is 0.7 times empty weight. What will be the gross weight of aircraft?

(a) 2157lb

(b) 215kg

(c) 950kg

(d) 1000lb

The question was asked by my college director while I was bunking the class.

Enquiry is from Conceptual Sketch Sizing in portion Conceptual Sketch Sizing of Aircraft Design

Answer 1

The correct answer is (a) 2157lb

Easy explanation: Given crew and payload = 180kg,

Empty weight fraction We / W0 = 0.48

Fuel weight is 0.7 times empty weight.

Hence, Wf = 0.7*We

Hence, Wf / W0 = 0.7*We / W0 = 0.7*0.48 = 0.336

Gross weight of aircraft is,

W0 = Wcrew + Wpayload + Wfuel + Wempty

By re-arranging,

W0 = Wcrew + Wpayload / [1 – (Wf/ W0) – (We / W0)]

= 180 / [1-0.336-0.48] = 978.26kg = 2157.06lb.