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Concept
Hypergolique
Résumé
A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other.
The two propellant components usually consist of a fuel and an oxidizer. The main advantages of hypergolic propellants are that they can be stored as liquids at room temperature and that engines which are powered by them are easy to ignite reliably and repeatedly. Common hypergolic propellants are difficult to handle due to their extreme toxicity or corrosiveness.
In contemporary usage, the terms "hypergol" and "hypergolic propellant" usually mean the most common such propellant combination: dinitrogen tetroxide plus hydrazine.
In 1935, Hellmuth Walter discovered that hydrazine hydrate was hypergolic with high-test peroxide of 80–83%. He was probably the first to discover this phenomenon, and set to work developing a fuel. Prof. Otto Lutz assisted the Walter Company with the development of C-Stoff which contained 30% hydrazine hydrate, 57% methanol, and 13% water, and spontaneously ignited with high strength hydrogen peroxide. BMW developed engines burning a hypergolic mix of nitric acid with various combinations of amines, xylidines and anilines.
Hypergolic propellants were discovered independently, for the second time, in the U.S. by GALCIT and Navy Annapolis researchers in 1940. They developed engines powered by aniline and red fuming nitric acid (RFNA). Robert Goddard, Reaction Motors, and Curtiss-Wright worked on aniline/nitric acid engines in the early 1940s, for small missiles and jet assisted take-off (JATO).The project resulted in the successful assisted take off of several Martin PBM and PBY bombers, but the project was disliked because of the toxic properties of both fuel and oxidizer, as well as the high freezing point of aniline. The second problem was eventually solved by the addition of small quantities of furfuryl alcohol to the aniline.
In Germany from the mid-1930s through World War II, rocket propellants were broadly classed as monergols, hypergols, non-hypergols and lithergols.
Source officielle
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