According to the Air BP website, the creation of jet fuel was needed following the development of the jet engine in Germany and the U.K. around the start of World War II. Early British jet engines of 1941 were powered by kerosene instead of gasoline because of gasoline shortages during the war.
The U.S. Centennial of Flight website reports early aircraft were powered by gasoline similar to that used in automobiles. During the 1930s Major Jimmie Doolittle realized a higher performing fuel was needed for aviation purposes if the U.S. was to take part in World War II. Doolittle helped develop aviation fuel, named AvGas, which was soon superseded by the need for higher quality jet fuel. Air BP explains that a gasoline-kerosene mix was developed for jet engines that was called JP1, and was improved quickly through to JP4 in 1951.
Initially, jet fuel was needed for military purposes. According to Air BP, one of the first improvements to jet fuel was to the amount of smoke and exhaust fumes that were visible in the sky. Another use developed by the military was the flashpoint, or temperature at which fuel fumes can be ignited by a naked flame. The U.S. Navy developed JP5 fuel with an even higher flashpoint than JP4. The chances of fire in the event of a crash were of primary importance in jet engine fuel.
The U.S. Centennial of Flight website explains that commercial jet aircraft use pure kerosene, instead of the gasoline-kerosene mix used by military aircraft. Commercial jet fuel, Jet-A, has a flashpoint of 120 degrees Fahrenheit, compared to regular gasoline with a flashpoint of 30 degrees Fahrenheit. Jet-A must pass stringent purity tests to be used in commercial aircraft. The U.S. Centennial of Flight website reports that when a fuel fails these tests, it is passed on to be used in ground-based vehicles, such as railroad engines.
Jet fuel as a gasoline-kerosene mix has had its properties altered as improvements were sought to raise the flashpoint and reduce the amount of harmful effects the fuel had on an engine. The U.S. Centennial of Flight reports that a jet fuel named JP7 was introduced with a flashpoint so high it was difficult to ignite in the engines of jet aircraft. To help the fuel ignite, a chemical called tri-ethyl borane (TEB) was added to JP7 because of its ability to burn at a high temperature when combined with the air. Adding TEB was the only way to ensure the jet fuel ignited to provide an engine with power.
The Shell website describes a number of additives that are combined with jet fuel in order to improve its properties. The amount and type of additives combined with jet fuels varies due to the type of fuel and its intended use. Some commonly used additives include metal deactivators, which reduce the harmful effects of metals within jet fuel, including copper. Shell also describes corrosion inhibitors, which reduce the corrosive effects of jet fuel on an engine by helping to lubricate the engine and maintaining performance.
