UNIFIED ENGINEERING Fall 2003
Problem U1. (Range Equation)
a) Assuming steady-level flight and no fuel reserves, estimate the range of a B-777 using
the information given in the lecture notes (and/or on Boeing’s web page). How well does
this compare to the estimates Boeing publishes on their web page?
b) Now assuming that L/D, propulsion system efficiency and final weight are unchanged,
estimate the range of a B-777 if the same volume of liquid hydrogen were to be used
instead of Jet-A.
c) Derive an equation for the range of a battery-powered aircraft in steady-level flight.
Express the range in terms of L/D, propulsion system efficiency, battery mass and
heating value, and aircraft weight. Estimate the range of a B-777 if the fuel was taken
out and replaced with its equivalent weight in batteries.
“FUEL” Heating Value (MJ/kg) Density (kg/m3)
Jet-A 42.8 800
Liquid Hydrogen 120 70
Batteries 2.5 8000
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