JP-7
Turbine Fuel Low Volatility JP-7, commonly known as JP-7 (referred to as Jet Propellant 7 prior to MIL-DTL-38219
Usage
JP-7 was developed for the Pratt & Whitney J58 (JT11D-20) turbojet engine, which was used primarily in the now retired Lockheed SR-71 Blackbird.[1] During flight, the SR-71 could attain speeds in excess of Mach 3+, which was the most efficient cruising speed for the J58 engines. However, very high skin temperatures are generated at this speed due to the rapid compression of the air along leading edges. A new jet fuel was needed that was not affected by the heat, so JP-7 jet fuel, with a high flash point and high thermal stability, was developed for this purpose.
The
History
"The operating envelope of the
impurities tolerated. Advanced fuels, JP-7 (PWA 535) and PWA 523E, were developed to meet the above requirements."
Composition
JP-7 is a compound mixture composed primarily of
JP-7 is unusual in that it is not a conventional
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 (−22 °F)
- Boiling point at 1 standard atmosphere (100 kPa): 282–288 °C (540–550 °F)
- Density at 15 °C (59 °F): 779–806 kg/m3
- Vapor pressure at 300 °F (149 °C): 155 kPa)
- Flashpoint: 60 °C (140 °F)
- Net )
See also
- JP-1
- JP-4
- JP-5
- JP-6
- JP-8
- JPTS
- Aviation fuel
- KC-135Q
References
- Notes
- ^ Note that a high luminometer number corresponds, somewhat counter-intuitively, to a low brightness for a given amount of heat generated.[7] Therefore, a high luminometer number means that, for a given amount of energy released in combustion, more of the energy goes into heating the gas, and less into heating the surrounding structure through radiative transfer, than would be the case for a low luminometer number fuel. But this does not say anything about other mechanisms of transfer, e.g., diffusive transfer, which may be greater or lesser.
- References
- ^ a b c d SR-71A Flight Manual (U), Issue E, Change 2. SR-71 Online - Paul R. Kucher. 31 July 1989. Retrieved 17 June 2017.
{{cite book}}:|website=ignored (help) - ^ "ASSIST Quick Search, Basic Profile: MIL-T-38219D Military Specification, Turbine Fuel, Low Volatility, JP-7". DLA.mil. DLA Document Services. 21 August 1998. Archived from the original on 22 February 2012.
- U.S. Air Force. 23 March 2011. Retrieved 17 June 2017.
- ^ "X-51 Waverider makes Historic Hypersonic Flight". ScientificComputing.com. Scientific Computing. 28 May 2010. Retrieved 17 June 2017.
- ^ Gregory W. Pedlow; Donald E. Welzenbach (1992). The Central Intelligence Agency and Overhead Reconnaissance: The U-2 and OXCART Programs, 1954-1974 (PDF). Washington DC: History Staff, Central Intelligence Agency. pp. 61–62. Archived from the original (PDF) on 22 April 2016.
{{cite book}}:|website=ignored (help) - ^ "Beale removes fuel storage tanks that kept Blackbird soaring". Beale Air Force Base. Retrieved 2020-07-29.
- .
- Bibliography
- Rich, Ben R. and Leo Janos. Skunk Works: A Personal Memoir of My Years at Lockheed. New York: Little, Brown and Company, 1994. ISBN 0-316-74330-5.
- 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.