JP-7

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Jet fuel formulation for certain supersonic aircraft

title: "JP-7" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["aviation-fuels", "shell-plc", "1955-introductions"] description: "Jet fuel formulation for certain supersonic aircraft" topic_path: "general/aviation-fuels" source: "https://en.wikipedia.org/wiki/JP-7" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Jet fuel formulation for certain supersonic aircraft ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b8/Pratt_&_Whitney_J58.jpg" caption="The [[Pratt & Whitney J58]] (JT11D-20) [[turbojet]] aero engine, which had a specific fuel requirement; namely JP-7 turbine fuel."] ::

Turbine Fuel Low Volatility JP-7, commonly known as JP-7 (referred to as Jet Propellant 7 prior to MIL-DTL-38219) is a specialized type of jet fuel developed at Pratt and Whitney by master chemist Clarence Brown CB Eichman in 1955 for the Central Intelligence Agency (CIA) for use in its reconnaissance aircraft, the Lockheed A-12, and subsequently for aircraft with similar high speed performance, the Lockheed YF-12 and Lockheed SR-71. It was also used for the higher speed Boeing X-51 Waverider.

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.

::quote[attribution="Mach]] flight, the fuel is also a [[heat sink]] for the various aircraft and engine accessories which would otherwise overheat at the high temperatures encountered. This requires a fuel having high thermal stability so that it will not break down and deposit [[Petroleum coke"] JT11D-20 engine]] requires special fuel. The fuel is not only the source of energy but is also used in the engine hydraulic system. During high [[Mach (speed) ::

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

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.

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