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JP-7
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<h2 id="usage">Usage</h2> <p>JP-7 was developed for the <a href="/facts/Pratt_%26_Whitney_J58/IoKE0jWT">Pratt & Whitney J58</a> (JT11D-20) <a href="/facts/Turbojet/tr3vYndL">turbojet</a> engine, which was used primarily in the <a href="/facts/Lockheed_SR-71_Blackbird/ESfv9oFq">Lockheed SR-71 Blackbird</a> which retired in 1999. The SR-71 design speed was <a href="/facts/Mach_number/Ee01MIgw">Mach</a> 3.2 at which very high skin temperatures occurred due to aerodynamic heating. A new jet fuel with a high <a href="/facts/Flash_point/97JQP35E">flash point</a> 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. </p><p>The <a href="/facts/Boeing_X-51/YDpmaYc9">Boeing X-51</a> Waverider also used JP-7 fuel in its <a href="/facts/Pratt_%26_Whitney/DI4FhYep">Pratt & Whitney</a> SJY61 <a href="/facts/Scramjet/2PdT7gKc">scramjet</a> engine, with fuel capacity of some 270 pounds (120 kg).<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p> <h2 id="composition">Composition</h2> <p>JP-7 is a compound mixture composed primarily of <a href="/facts/Hydrocarbon/Dcg95Ju5">hydrocarbons</a>; including <a href="/facts/Alkane/Qam7Hvmf">alkanes</a>, <a href="/facts/Cycloalkane/8dQAoD1N">cycloalkanes</a>, <a href="/facts/Aromatic_hydrocarbon/3EXq8Tgf">alkylbenzenes</a>, <a href="/facts/Indane/x6xKFHwh">indanes</a>/<a href="/facts/Tetralin/0YFvrDQq">tetralins</a>, and <a href="/facts/Naphthalene/RU2sV8mN">naphthalenes</a>; with addition of <a href="/facts/Fluorocarbon/jA9N6aoT">fluorocarbons</a> to increase its <a href="/facts/Lubricant/9PXISDwU">lubricant</a> properties, an oxidizing agent to make it burn more efficiently, and a <a href="/facts/Caesium/dXKN1S5k">caesium</a>-containing compound known as A-50, which is to aid in disguising the <a href="/facts/Radar/jk9BTbFA">radar</a> and <a href="/facts/Infrared_signature/od3S5Axr">infrared signatures</a> of the <a href="/facts/Exhaust_plume/kLpq1eUX">exhaust plume</a>. The SR-71 Blackbirds used approximately 36,000–44,000 pounds (16,000–20,000 kg) of fuel per hour of flight.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p><p>JP-7 is unusual in that it is not a conventional <a href="/facts/Distillation/plDvUMxn">distillate</a> fuel, but is created from special blending stocks in order to have very low (<3%) concentration of highly volatile components like <a href="/facts/Benzene/Fguue7nr">benzene</a> or <a href="/facts/Toluene/Pzdt8dwD">toluene</a>, and almost no <a href="/facts/Sulfur/IK0amTfM">sulfur</a>, <a href="/facts/Oxygen/acyn6o8r">oxygen</a>, and <a href="/facts/Nitrogen/Nf1QpGDz">nitrogen</a> impurities. It has a low vapor pressure, and high thermal oxidation stability. The fuel must operate across a wide range of temperatures: from near freezing at high altitude, to the high temperatures of the airframe and engine parts that are being cooled by it at high speed. Its <a href="/facts/Volatility_(physics)/90r3ep6w">volatility</a> must be low enough to make it flash-resistant at these high temperatures. </p><p>The very low volatility, and relative unwillingness of JP-7 to be ignited, required <a href="/facts/Triethylborane/qLlyzN2r">triethylborane</a> (TEB) to be injected into the engine in order to initiate combustion, and allow <a href="/facts/Afterburner/aDeuyqp3">afterburner</a> 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. </p> <h2 id="properties">Properties</h2> <ul><li>Melting point: −30 <a href="/facts/Celsius/okAEu1CA">°C</a> (−22 <a href="/facts/Fahrenheit/2TVmyJod">°F</a>)</li> <li>Boiling point at 1 <a href="/facts/Atmosphere_(unit)/aTbYALII">standard atmosphere</a> (100 <a href="/facts/Pascal_(unit)/Am1To2Qm">kPa</a>): 282–288 °C (540–550 °F)</li> <li>Density at 15 °C (59 °F): 779–806 <a href="/facts/Kilogram_per_cubic_metre/a3Qs7uBX">kg/m3</a></li> <li>Vapor pressure at 300 °F (149 °C): 155 <a href="/facts/Millimetre_of_mercury/qVG9oG1d">millimetres of mercury</a> (3.00 <a href="/facts/Pound_per_square_inch/RMdeTlB0">psi</a>) (20.7 <a href="/facts/KPa/Am1To2Qm">kPa</a>)</li> <li>Flashpoint: 60 °C (140 °F)</li> <li>Net <a href="/facts/Heat_of_combustion/HdQX0mPP">heat of combustion</a>: min. 43.5 <a href="/facts/Megajoule/9ndq9jD2">megajoules</a> per <a href="/facts/Kilogram/lU2zbPk8">kilogram</a> (5.48 <a href="/facts/Kilowatt-hour/qvVkEmPH">kWh</a>/<a href="/facts/Pound_(mass)/BNIGRRDI">lb</a>)</li></ul> <h2 id="see-also">See also</h2> <ul> <li>Energy portal</li></ul> <ul><li><a href="/facts/JP-1/4CDswF3t">JP-1</a></li> <li><a href="/facts/JP-4_(fuel)/xlGS536M">JP-4</a></li> <li><a href="/facts/JP-5/4CDswF3t">JP-5</a></li> <li><a href="/facts/JP-6/4CDswF3t">JP-6</a></li> <li><a href="/facts/JP-8/pfMUahpw">JP-8</a></li> <li><a href="/facts/JP-10_(fuel)/gG6mDRlw">JP-10</a></li> <li><a href="/facts/JPTS/znzUtcva">JPTS</a></li> <li><a href="/facts/Aviation_fuel/XGW64rro">Aviation fuel</a></li> <li><a href="/facts/KC-135_Stratotanker/hRmEJPJv">KC-135Q</a></li></ul> Notes References Bibliography <ul><li>Rich, Ben R. and Leo Janos. <i>Skunk Works: A Personal Memoir of My Years at Lockheed</i>. New York: Little, Brown and Company, 1994. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 0-316-74330-5.</li> <li>Faroon, Obaid; Mandell, Diane; Navarro, Hernan. <a href="https://www.atsdr.cdc.gov/ToxProfiles/tp76.pdf"><i>Toxicological Profile for Jet Fuels JP-4 and JP-7</i></a>. <a href="/facts/Agency_for_Toxic_Substances_and_Disease_Registry/jVG5SPBA">Agency for Toxic Substances and Disease Registry</a>, Atlanta, June 1995.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"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. <a href="https://web.archive.org/web/20120222064453/https://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=21921" target="_blank">https://web.archive.org/web/20120222064453/https://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=21921</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Factsheets: X-51A Waverider". AF.mil. U.S. Air Force. 23 March 2011. Retrieved 17 June 2017. <a href="https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104467/x-51a-waverider/" target="_blank">https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104467/x-51a-waverider/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Beale removes fuel storage tanks that kept Blackbird soaring". Beale Air Force Base. Retrieved 2020-07-29. <a href="https://www.beale.af.mil/News/Article-Display/Article/667324/beale-removes-fuel-storage-tanks-that-kept-blackbird-soaring/" target="_blank">https://www.beale.af.mil/News/Article-Display/Article/667324/beale-removes-fuel-storage-tanks-that-kept-blackbird-soaring/</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> </ol>