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Following diagram is showing mission profile with different phases with mission segment fuel fraction as shown. If crew weight is 150kg, payload of 600kg and empty fraction of 0.495. Determine gross weight of the aircraft.(a) 4430kg(b) 39810kg(c) 4431lb(d) 38910lbThe question was asked during an interview for a job.I need to ask this question from Conceptual Sketch Sizing topic in chapter Conceptual Sketch Sizing of Aircraft Design |
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Answer» CORRECT choice is (a) 4430kg Easy explanation: Given crew WEIGHT = 150kg, payload weight = 600kg Fuel weight fraction Wf / W0 = 1.06[1 – Wx/W0], Now from fuel fraction method, Wx / W0 = MULTIPLICATION of each phase fraction = 0.975*0.98*0.96*0.8*0.96*0.97 = 0.6833 Now, Wf / W0 = 1.06 * [1 – (Wx / W0)] = 0.3357 Empty weight fraction We / W0 = 0.481 Gross weight of aircraft is, W0 = Wcrew + Wpayload + Wfuel + Wempty By re-arranging, W0 = Wcrew + Wpayload / [1 – (Wf/ W0) – (We / W0)] = 150 + 600 / [1-0.3357-0.495] = 4430kg |
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