In aerospace engineering, payload fraction is a common term used to characterize the efficiency of a particular design. Payload fraction is calculated by dividing the weight of the payload by the weight of the otherwise empty aircraft when fully fueled. Fuel represents a considerable amount of the overall takeoff weight, and for shorter trips it is quite common to load less fuel in order to carry a lighter load. For this reason the useful load fraction calculates a similar number, but based on the combined weight of the payload and fuel together.
Propeller-driven airliners had useful load fractions on the order of 25-35%. Modern jet-powered airliners have considerably higher useful load fractions, on the order of 45-55%.
For spacecraft the payload fraction is often less than 1%, while the useful load fraction is perhaps 90%. In this case the useful load fraction is not a useful term, because spacecraft typically can't reach orbit without a full fuel load. For this reason the related term mass fraction, is used instead. However, if the latter is large, the payload can only be small.
Other articles related to "payload fraction, fraction, payload":
... Takeoff Mass Final Mass Mass ratio Mass fraction Ariane 5 (vehicle + payload) 746,000 kg (~1,645,000 lb) 2,700 kg + 16,000 kg (~6,000 lb + ~35,300 lb) 39.9 0.975 Titan ...
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