as a heat-sink for aircraft air conditioning and hydraulic systems and engine accessories. JP-8 is a jet fuel, specified and used widely by the U.S. military. It is specified by MIL-DTL-83133 and British Defence Standard 91-87. JP-8 is a kerosene-based fuel, projected to remain in use at least until 2025. The United States military uses JP-8 as a "universal fuel" in both turbine-powered aircraft and diesel-powered ground vehicles. It was first introduced at NATO bases in 1978. Its NATO code is F-34. JP-9 is a gas turbine fuel for missiles, specifically the Tomahawk cruise missile, containing the TH-dimer (tetrahydrodimethyldicyclopentadiene) produced by catalytic hydrogenation of methylpentadiene dimer. JP-10 is a gas turbine fuel for missiles, specifically the AGM-86 ALCM cruise missile. It contains a mixture of (in decreasing order) endo-tetrahydrodicyclopentadiene, exo-tetrahydrodicyclopentadiene (a synthetic fuel), and adamantane. It is produced by catalytic hydrogenation of dicyclopentadiene. It superseded JP-9 fuel, achieving a lower low-temperature service limit of . It is also used by the Tomahawk jet-powered subsonic cruise missile. JPTS was a combination of LF-1 charcoal lighter fluid and an additive to improve thermal oxidative stability officially known as "Thermally Stable Jet Fuel". It was developed in 1956 for the Pratt & Whitney J57 engine which powered the Lockheed U-2 spy plane. Zip fuel designates a series of experimental boron-containing "high energy fuels" intended for long range aircraft. The toxicity and undesirable residues of the fuel made it difficult to use. The development of the ballistic missile removed the principal application of zip fuel. Syntroleum has been working with the USAF to develop a synthetic jet fuel blend that will help them reduce their dependence on imported petroleum. The USAF, which is the United States military's largest user of fuel, began exploring alternative fuel sources in 1999. On December 15, 2006, a B-52 took off from Edwards Air Force Base for the first time powered solely by a 50–50 blend of JP-8 and Syntroleum's FT fuel. The seven-hour flight test was considered a success. The goal of the flight test program was to qualify the fuel blend for fleet use on the service's B-52s, and then flight test and qualification on other aircraft. Piston engine use Jet fuel is very similar to diesel fuel, and in some cases, may be used in diesel engines. The possibility of environmental legislation banning the use of leaded avgas (fuel in spark-ignited internal combustion engine, which usually