In
aerospace engineering
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is s ...
, payload fraction is a common term used to characterize the efficiency of a particular design. The payload fraction is the quotient of the payload mass and the total vehicle mass at the start of its journey. It is a function of
specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine, such as a rocket engine, rocket using propellant or a jet engine using fuel, generates thrust. In general, this is a ratio of the ''Impulse (physics), ...
,
propellant mass fraction and the
structural coefficient. In aircraft, loading less than full fuel for shorter trips is standard practice to reduce weight and fuel consumption. For this reason, the useful load fraction calculates a similar number, but it is based on the combined weight of the payload and fuel together in relation to the total weight.
Propeller-driven
airliner
An airliner is a type of airplane for transporting passengers and air cargo. Such aircraft are most often operated by airlines. The modern and most common variant of the airliner is a long, tube shaped, and jet powered aircraft. The largest ...
s had useful load fractions on the order of 25–35%. Modern
jet airliner
A jet airliner or jetliner is an airliner powered by jet engines (passenger jet aircraft). Airliners usually have twinjet, two or quadjet, four jet engines; trijet, three-engined designs were popular in the 1970s but are less common today. Air ...
s have considerably higher useful load fractions, on the order of 45–55%.
For
orbital rockets the payload fraction is between 1% and 5%, while the useful load fraction is perhaps 90%.
Examples
For payload fractions and fuel fractions in aviation, see
Fuel Fraction.
See also
*
Tsiolkovsky rocket equation
The classical rocket equation, or ideal rocket equation is a mathematical equation that describes the motion of vehicles that follow the basic principle of a rocket: a device that can apply acceleration to itself using thrust by expelling part o ...
References
{{DEFAULTSORT:Payload Fraction
Astrodynamics
Aerospace engineering