Editing Hypergolic propellant (section)

== History ==
The fact that [[turpentine]] may spontaneously combust when mixed with [[nitric acid]] was discovered as early as the late 17th century by [[Frederick Slare]],<ref>{{Cite journal |last=Slare |first=Frederick |date=1694 |title=An Account of Some Experiments Relating to the Production of Fire and Flame, Together with an Explosion; Made by the Mixture of Two Liquors Actually Cold |url=https://www.jstor.org/stable/102461 |journal=Philosophical Transactions  |volume=18 |pages=201–218 |jstor=102461 |issn=0260-7085}}</ref><ref>{{Cite book |last=Newman |first=William R. |url=https://books.google.com/books?id=NXGYDwAAQBAJ&pg=PA457 |title=Newton the Alchemist: Science, Enigma, and the Quest for Nature's "Secret Fire" |date=2018-12-11 |publisher=Princeton University Press |isbn=978-0-691-17487-7 |language=en}}</ref> but it remained a scientific curiosity for centuries until it was proposed to use it for [[rocket-assisted take off]] during WWII.<ref>{{US patent|2489051A}}</ref>

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 [[Hellmuth Walter Kommanditgesellschaft|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]].<ref name="Ignition" />{{rp|13}} BMW developed engines burning a hypergolic mix of nitric acid with various combinations of amines, xylidines, and [[aniline]]s.<ref name="Benecke">{{cite book |chapter=BMW Developments |last=Lutz |first=O. | editor1-last=Benecke | editor1-first=T. H. | editor2-last=Quick | editor2-first=A.W. | editor3-last=Schulz | editor3-first=W. | title=History of German Guided Missiles Development (Guided Missiles Seminar. 1956. Munich) | publisher=Appelhans | series=Advisory Group for Aerospace Research and Development-AG-20 | year=1957 | url=https://books.google.com/books?id=O5tNswEACAAJ | pages=420}}</ref>

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]].<ref name="Sutton">{{cite book | last=Sutton | first=G. P. | title=History of Liquid Propellant Rocket Engines | publisher=American Institute of Aeronautics and Astronautics | series=Library of flight | year=2006 | isbn=978-1-56347-649-5 | url=https://books.google.com/books?id=s1C9Oo2I4VYC}}</ref> [[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 JATO of several [[Martin PBM Mariner|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.<ref name="Ignition"/>{{rp|22-23}}

[[File:Walter Triebwerk HWK109-509 A Luftwaffenmuseum Berlin-Gatow Denis Apel.JPG|thumb|right|An early hypergolic-propellant rocket engine, the Walter 109-509A of 1942–45]]
In Germany from the mid-1930s through [[World War II]], rocket propellants were broadly classed as [[monergol]]s, hypergols, nonhypergols and [[Hybrid-propellant rocket|lithergols]]. The ending ''ergol'' is a combination of [[Greek language|Greek]] ''ergon'' or work, and Latin ''oleum'' or oil, later influenced by the chemical suffix ''-ol'' from [[Alcohol (chemistry)|alcohol]].<ref group="Note">"-ergol", ''Oxford English Dictionary''</ref>  Monergols were [[monopropellant]]s, while nonhypergols were [[Bipropellant rocket|bipropellants]] that required external ignition, and lithergols were solid/liquid hybrids. Hypergolic propellants (or at least hypergolic ignition) were far less prone to [[hard start]]s than electric or pyrotechnic ignition. The "hypergole" terminology was coined by Dr. Wolfgang Nöggerath, at the Technical University of [[Braunschweig]] (Brunswick), Germany.<ref>{{citation |title=Peenemünde West: Die Erprobungsstelle der Luftwaffe für geheime Fernlenkwaffen und deren Entwicklungsgeschichte |trans-title=Peenemünde West: The Luftwaffe's test center for secret guided missiles and the history of their development |last=Botho |first=Stüwe |location=Peene Münde West |publisher=Weltbildverlag |isbn=9783828902947 |year=1998 |page=220 |language=de}}</ref>

The only rocket-powered fighter ever deployed was the [[Messerschmitt Me 163]]B ''Komet'', which had an [[HWK 109-509]], a rocket motor which consumed methanol/hydrazine as fuel and high-test peroxide ''[[T-Stoff]]'' as oxidizer. The hypergolic rocket motor had the advantage of fast climb and quick-hitting tactics at the cost of being very volatile and capable of exploding with any degree of inattention. Other proposed combat rocket fighters such as the [[Heinkel P.1077|Heinkel ''Julia'']] and reconnaissance aircraft like the [[DFS 228]] were meant to use the Walter 509 series of rocket motors, but besides the Me 163, only the [[Bachem Ba 349]] ''Natter'' vertical launch expendable fighter was ever flight-tested with the Walter rocket propulsion system as its primary sustaining thrust system for military-purpose aircraft.

The earliest [[ballistic missiles]], such as the Soviet [[Sputnik (rocket)|R-7]] that launched [[Sputnik 1]] and the U.S. [[Atlas (rocket family)|Atlas]] and [[HGM-25A Titan I|Titan-1]], used [[kerosene]] and [[liquid oxygen]]. Although they are preferred in space launchers, the difficulties of storing a [[cryogenics|cryogen]] such as liquid oxygen in a missile that had to be kept launch ready for months or years at a time led to a switch to hypergolic propellants in the U.S. [[LGM-25C Titan II|Titan II]] and in most Soviet ICBMs such as the [[R-36 (missile)|R-36]], but the difficulties of such corrosive and toxic materials, including injury-causing leaks and the explosion of a Titan-II in its silo,<ref>{{Cite book |last=Schlosser |first=Eric |title=Command and control: nuclear weapons, the Damascus Accident, and the illusion of safety |date=2013 |publisher=The Penguin Press |isbn=978-1-59420-227-8 |location=New York, NY}}</ref> led to their near universal replacement with [[Solid-fuel rocket|solid-fuel]] boosters, first in Western [[SLBM|submarine-launched ballistic missiles]] and then in land-based U.S. and Soviet ICBMs.<ref name="Ignition"/>{{rp|47}}

In the 1960s, late variants of French [[Véronique (rocket)|Véronique]] [[sounding rocket]] and the [[Vesta (rocket)|Vesta]] rocket, as well as the first stage of the first orbital SLV [[Diamant]] used<ref>{{Cite web |title=Nitric acid/Turpentine |url=http://www.astronautix.com/n/nitricacidturpentine.html |access-date=2024-11-30 |website=www.astronautix.com}}</ref> the combination of nitric acid and turpentine discovered by Slare. It may also be used in [[amateur rocketry]].<ref>{{Cite web |title=Breaking Bad rocket style: Cooking fuel in a trailer lab {{!}} Pythom Space |url=https://www.pythomspace.com/updates/breaking-bad-rocket-style-cooking-fuel-in-a-trailer-lab |access-date=2024-11-30 |website=www.pythomspace.com |language=en}}</ref>

The [[Apollo Lunar Module]], used in the [[Apollo program|Moon landings]], employed hypergolic fuels in both the descent and ascent rocket engines. The [[Apollo command and service module|Apollo spacecraft]] used the same combination for the [[Service Propulsion System]]. Those spacecraft and the [[Space Shuttle]] (among others) used hypergolic propellants for their [[reaction control system]]s.

The trend among Western space-launch agencies is away from large hypergolic rocket engines and toward hydrogen/oxygen engines or methane/oxygen and [[RP-1]]/oxygen engines for various [[Liquid-propellant_rocket#Advantages_and_disadvantages|advantages and disadvantages]]. [[Ariane (rocket family)|Arianes]] 1 through 4, with their hypergolic [[Multistage rocket|first and second stages]] (and optional hypergolic boosters on the Ariane 3 and 4) have been retired and replaced with the Ariane 5, which uses a first stage fueled by liquid hydrogen and liquid oxygen. The Titan II, III, and IV, with their hypergolic first and second stages, have also been retired for the Atlas V (RP-1/oxygen) and Delta IV (hydrogen/oxygen). Hypergolic propellants are still used in upper stages, when multiple burn-coast periods are required, and in [[launch escape system]]s.