JP-7

Usage

JP-7 was developed for the Pratt & Whitney J58 (JT11D-20) turbojet engine, which was used primarily in the Lockheed SR-71 Blackbird which retired in 1999. The SR-71 design speed was Mach 3.2 at which very high skin temperatures occurred due to aerodynamic heating. A new jet fuel with a high flash point and high thermal stability was developed as the fuel had to be used as a heat sink for the severe high temperature environment in the aircraft.

The Boeing X-51 Waverider also used JP-7 fuel in its Pratt & Whitney SJY61 scramjet engine, with fuel capacity of some 270 lbs.

Composition

JP-7 is a compound mixture composed primarily of [hydrocarbons; including alkanes, cycloalkanes, alkylbenzenes, indanes/tetralins, and naphthalenes; with addition of fluorocarbons to increase its lubricant properties, an oxidizing agent to make it burn more efficiently, and a caesium-containing compound known as A-50, which is to aid in disguising the radar and infrared signatures of the exhaust plume. The SR-71 Blackbirds used approximately 36000 - of fuel per hour of flight.

JP-7 is unusual in that it is not a conventional distillate fuel, but is created from special blending stocks in order to have very low (

The very low volatility, and relative unwillingness of JP-7 to be ignited, required triethylborane (TEB) to be injected into the engine in order to initiate combustion, and allow afterburner operation in flight. The SR-71 had a limited capacity for TEB, and therefore had a limited number of available 'shots' of TEB (usually 16) for restarts, and those had to be managed carefully on long-duration flights with multiple stages of relatively low-altitude air refueling and normal high-altitude cruise flight.

Properties

• Melting point: -30 C
• Boiling point at 1 atm: 282 -
• Density at 15 C: 779–806 kg/m3
• Vapor pressure at 300 F: 155 mmHg (20.7 kPa)
• Flashpoint: 60 C
• Net heat of combustion: min. 43.5 MJ/kg

References

;Notes

;References

;Bibliography

• Rich, Ben R. and Leo Janos. Skunk Works: A Personal Memoir of My Years at Lockheed. New York: Little, Brown and Company, 1994. .
• Faroon, Obaid; Mandell, Diane; Navarro, Hernan. Toxicological Profile for Jet Fuels JP-4 and JP-7. Agency for Toxic Substances and Disease Registry, Atlanta, June 1995.

References

1. (21 August 1998). "ASSIST Quick Search, Basic Profile: MIL-T-38219D Military Specification, Turbine Fuel, Low Volatility, JP-7". DLA Document Services.
2. (23 March 2011). "Factsheets: X-51A Waverider". [[U.S. Air Force]].
3. "SR-71 Flight Manual".
4. "Beale removes fuel storage tanks that kept Blackbird soaring".
5. (1961). "Relation of Luminometer Number to Molecular Structure and Smoke Point". Journal of Chemical & Engineering Data.