Fuel fraction

An aircraft's fuel fraction, fuel weight fraction, [cite book | last = Brandt | first = Steven | title = Introduction to Aeronautics: a Design Perspective | publisher = AIAA (American Institute of Aeronautics & Ast | pages = p. 359 | year = 2004 | isbn = 1563477017 ] or propellant fraction is the weight of the fuel or propellant divided by the gross take-off weight of the aircraft (including propellant): [cite book | last = Vinh | first = Nguyen | title = Flight Mechanics of High-Performance Aircraft | publisher = Cambridge University Press | location = Cambridge | pages = p. 139| year = 1993 | isbn = 0521478529 ]

:$zeta\; =\; frac\{Delta\; W\}\{W\_1\}$

The result of this mathematical division is often expressed as a percent.

Fuel fraction is a key parameter in determining an aircraft's range, the distance it can fly without refueling.

For aircraft with external drop tanks, the term internal fuel fraction is used to exclude the weight of external tanks and fuel. Breguet’s aircraft range equation describes the relationship of range with airspeed, lift-to-drag ratio, specific fuel consumption, and the part of the total fuel fraction available for cruise, also known as the cruise fuel fraction, or cruise fuel weight fraction. [cite book
title=Flight Performance of Fixed and Rotary Wing Aircraft
author=Filippone, Antonio
year=2006
publisher=Elsevier
pages=426
isbn=0750668172]

Fighter aircraft

At today’s state of the art for jet fighter aircraft, fuel fractions of 29 percent and below typically yield subcruisers; 33 percent provides a quasi–supercruiser; and 35 percent and above are needed for useful supercruising missions. The U.S. F-22 Raptor’s fuel fraction is 29 percent [ [http://www.af.mil/factsheets/factsheet.asp?fsID=199 8200/27900 = 0.29] ] , Eurofighter is 31 percent, both similar to those of the subcruising F-4 Phantom II, F-15 Eagle and the Russian Mikoyan MiG-29 "Fulcrum". The Russian supersonic interceptor, the Mikoyan MiG-31 "Foxhound", has a fuel fraction of over 45 percent. [ [http://www.pogo.org/p/defense/do-000812-f22.htm The F-22 Program FACT VERSUS FICTION] by Everest E. Riccioni, Col. USAF, Ret.] The Panavia Tornado had a relatively low internal fuel fraction of 26 percent, and frequently carried drop tanks. [cite book | last = Spick | first = Mike | title = Brassey's Modern Fighters | publisher = Potomac Books | location = Washington | year = 2002 | page = pp. 51-53 | isbn = 157488462X ]

Airliners

Airliners typically have a fuel fraction between 25 to 45 percent, so less than half their takeoff weight is fuel. The Boeing 777-200-IGW very long range airliner has a fuel fraction of 47 percent. [ [http://www.mh-aerotools.de/company/paper_7/astec_2002.htm The Sonic Cruiser – A Concept Analysis] by Dr. Martin Hepperle] Concorde had a high fuel fraction of around 55%. [ [http://mae.ucdavis.edu/faculty/sarigul/AIAA_2003_0909_revised_Sep03.pdf Manned Sub-Orbital Space Transportation Vehicles ] ] The Rutan Voyager took off on its 1986 around-the-world flight at 72 percent, the highest figure ever at the time. [cite journal
journal=Popular Mechanics
title=Burt Rutan and the Ultimate Solo
author=Noland, David
month=February
year=2005
url=http://www.popularmechanics.com/science/air_space/1262012.html?page=3] Steve Fossett's Virgin Atlantic GlobalFlyer could attain a fuel fraction of nearly 85 percent, meaning that it carried more than six times its empty weight in fuel. [cite news
first = Mike
last = Schneider
title = Adventurer Set for Record-Setting Flight
url = http://www.space.com/news/ap_060206_fosset_flight.html
work = Associated Press
publisher = Space.com
date = 2006-02-06
accessdate = 2007-03-18
quote = At takeoff, fuel is expected to account for almost 85 percent of the graphite-made aircraft's weight. ]

See also

*Mass ratio

References