Editing Unsymmetrical dimethylhydrazine (section)

== Uses ==
UDMH is often used in [[hypergolic]] [[rocket fuel]]s as a [[bipropellant]] in combination with the oxidizer [[nitrogen tetroxide]] and less frequently with [[IRFNA]] (inhibited red fuming nitric acid) or [[liquid oxygen]].<ref>{{Cite journal |last1=Semenkov |first1=Ivan |last2=Koroleva |first2=Tatyana |date=1 December 2022 |title=Review on the environmental impact of emissions from space launches: a case study for areas affected by the Russian space programme |url=https://doi.org/10.1007/s11356-022-23888-8 |journal=Environmental Science and Pollution Research |language=en |volume=29 |issue=60 |pages=89807–89822 |doi=10.1007/s11356-022-23888-8 |pmid=36346528 |bibcode=2022ESPR...2989807S |s2cid=253396676 |issn=1614-7499}}</ref> UDMH is a derivative of [[hydrazine]] and is sometimes referred to as a hydrazine. As a fuel, it is described in specification MIL-PRF-25604 in the United States.<ref>{{cite web|title=Performance Specification Propellant, uns-Dimethylhydrazine (MIL-PRF-25604F)|url=https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=18058|date=11 March 2014|website=ASSIST Database Quicksearch|access-date=26 May 2020}}</ref>

UDMH is stable and can be kept loaded in rocket fuel systems for long periods, which makes it appealing for use in many [[liquid rocket]] engines, despite its cost. In some applications, such as the OMS in the [[Space Shuttle]] or [[orbital maneuvering system|maneuvering engines]], [[monomethylhydrazine]] is used instead due to its slightly higher [[specific impulse]].
In some kerosene-fueled rockets, UDMH functions as a starter fuel to start combustion and warm the rocket engine prior to switching to kerosene.

UDMH has higher stability than hydrazine, especially at elevated temperatures, and can be used as its replacement or together in a mixture. UDMH is used in many European, Russian, Indian, and Chinese rocket designs. The Russian [[UR-100|SS-11 Sego]] (aka 8K84) ICBM, [[UR-100N|SS-19 Stiletto]] (aka 15A30) ICBM, [[Proton (rocket)|Proton]], [[Kosmos-3M]], [[R-29RMU2 Layner]], [[R-36M]], [[Rokot]] (based on 15A30) and the Chinese [[Long March 2]] are the most notable users of UDMH (which is referred to as "heptyl" (codename from [[USSR|Soviet era]]){{Citation needed|date=October 2020}} by Russian engineers<ref>{{cite web|title = Following Russian rocket explosion, experts warn of 'major contamination'|date = 2 July 2013|url = https://www.theverge.com/2013/7/2/4487096/russian-rocket-explosion-proton-heptyl-contamination}}</ref>). The [[Titan (rocket family)|Titan]], [[Geosynchronous Satellite Launch Vehicle|GSLV]], and [[Delta rocket]] families use a mixture of 50% hydrazine and 50% UDMH, called [[Aerozine 50]], in different stages.<ref>{{Cite book | last = Clark | first = John D. | author-link = John Drury Clark | title = Ignition! An Informal History of Liquid Rocket Propellants | publisher = Rutgers University Press | year = 1972 | page = 45 | isbn = 0-8135-0725-1 }}</ref> There is speculation that it is the fuel used in the ballistic missiles that North Korea has developed and tested in 2017.<ref>{{cite news|url=https://www.nytimes.com/2017/09/17/world/asia/north-korea-rocket-fuel-missiles.html|title=The Rare, Potent Fuel Powering North Korea's Weapons|first1=William J.|last1=Broad|first2=David E.|last2=Sanger|newspaper=The New York Times|date=17 September 2017}}</ref>