Editing RP-1 (section)

==Usage and history==
[[File:Apollo 8 Liftoff.jpg|thumb|alt=Photo of Saturn V rocket lifting off|[[Apollo 8]], [[Saturn V]] with 810,700 litres of RP-1 and 1,311,100 liters of [[LOX]] in the [[S-IC]] first stage<ref name="Stages Saturn">{{cite book |last=Bilstein |first=Roger E. |date=1996 |orig-date=1980 |title=Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles |section=Appendix A—Schematic of Saturn V |page=405 |series=The NASA History Series |section-url=https://history.nasa.gov/SP-4206/p405.htm |url-status=live |publisher=[[NASA]] |isbn=0-16-048909-1 |archive-url=https://web.archive.org/web/20081101191827/https://history.nasa.gov/SP-4206/p405.htm |archive-date=2008-11-01}} Digitized copies are available from the Internet Archive: [https://archive.org/details/stagestosaturnte00bilsrich 1996 edition]; [https://archive.org/details/NASA_NTRS_Archive_19970009949 first edition].</ref>]]
RP-1 is a fuel in the first-stage boosters of the [[Electron rocket|Electron]], [[Soyuz (rocket family)|{{Transliteration|ru|Soyuz|italics=no}}]], [[Zenit (rocket family)|{{Transliteration|uk|Zenit|italics=no}}]], [[Delta rocket|Delta I-III]], [[Atlas (rocket)|Atlas]], [[Falcon rocket|Falcon]], [[Antares rocket|Antares]], and [[Tronador (rocket)|{{langr|es|Tronador II|nocat=y}}]] rockets. It also powered the first stages of the [[Energia (rocket)|{{Transliteration|ru|Energia|italics=no}}]], [[Titan I]], [[Saturn I (rocket)|Saturn I and IB]], and [[Saturn V]]. The [[Indian Space Research Organization]] (ISRO) is also developing an RP-1 fueled engine for its future rockets.<ref name="isro">{{cite web | title=ISRO Annual Report 2013-14 | website=isro.org | date=18 October 2015 | url=http://www.isro.org/sites/default/files/AnnualReports/2014/STS.html | archive-url=https://web.archive.org/web/20151018185434/http://www.isro.org/sites/default/files/AnnualReports/2014/STS.html | archive-date=18 October 2015 | url-status=dead | access-date=2 June 2022}}</ref>{{Update inline|date=January 2025}}

===Development===
During and immediately after World War II, alcohols (primarily [[ethanol]], occasionally [[methanol]]) were commonly used as fuels for large [[liquid-fueled rockets]]. Their high [[heat of vaporization]] kept [[Regenerative cooling (rocket)|regeneratively-cooled]] engines from melting, especially considering that alcohols would typically contain several percent water. However, it was recognized that [[hydrocarbon]] fuels would increase engine efficiency, due to a slightly higher [[density]], the lack of an [[oxygen]] atom in the fuel molecule, and negligible water content. Regardless of which hydrocarbon was chosen, it would also have to replace alcohol as a coolant.

Many early rockets burned [[kerosene]], but as burn times, combustion efficiencies, and combustion-chamber pressures increased, engine masses decreased, which led to unmanageable engine temperatures. Raw kerosene used as coolant tends to [[Dissociation (chemistry)|dissociate]] and [[Polymerization|polymerize]]. Lightweight products in the form of gas bubbles cause cavitation, and heavy ones in the form of wax deposits block narrow cooling passages in the engine. The resulting coolant starvation raises temperatures further, and causes more polymerization which accelerates breakdown. The cycle rapidly escalates (i.e., [[thermal runaway]]) until an engine wall rupture or other mechanical failure occurs, and it persists even when the entire coolant flow consists of kerosene. In the mid-1950s rocket designers turned to chemists to formulate a heat-resistant hydrocarbon, with the result being RP-1.

During the 1950s, LOX ([[liquid oxygen]]) became the preferred oxidizer to use with RP-1,<ref name=Sutton2006>{{cite book
 | title=History of Liquid Propellant Rocket Engines
 | first=George Paul | last=Sutton | date=2006
 | publisher=American Institute of Aeronautics and Astronautics
 | page=42 | isbn=9781563476495
 | url=https://books.google.com/books?id=s1C9Oo2I4VYC&pg=PA42
}}</ref> though other [[oxidizers]] have also been employed.