Editing Rocket engine (section)

==Safety==
[[Rocket]] vehicles have a reputation for unreliability and danger; especially catastrophic failures. Contrary to this reputation, carefully designed rockets can be made arbitrarily reliable.{{Citation needed|date=January 2017}} In military use, rockets are not unreliable. However, one of the main non-military uses of rockets is for orbital launch. In this application, the premium has typically been placed on minimum weight, and it is difficult to achieve high reliability and low weight simultaneously. In addition, if the number of flights launched is low, there is a very high chance of a design, operations or manufacturing error causing destruction of the vehicle.{{Citation needed|date=January 2017}}

===Saturn family (1961–1975)===
The [[Rocketdyne H-1]] engine, used in a cluster of eight in the first stage of the [[Saturn I]] and [[Saturn IB]] [[launch vehicle]]s, had no catastrophic failures in 152 engine-flights. The [[Pratt and Whitney]] [[RL10]] engine, used in a cluster of six in the Saturn I second stage, had no catastrophic failures in 36 engine-flights.{{refn|group=notes|name=RL10|The RL10 ''has'', however, experienced occasional failures (some of them catastrophic) in its other use cases, as the engine for the much-flown [[Centaur (rocket stage)|Centaur]] and [[Delta Cryogenic Second Stage|DCSS]] upper stages.}} The [[Rocketdyne F-1]] engine, used in a cluster of five in the first stage of the [[Saturn V]], had no failures in 65 engine-flights. The [[Rocketdyne J-2]] engine, used in a cluster of five in the Saturn V second stage, and singly in the Saturn IB second stage and Saturn V third stage, had no catastrophic failures in 86 engine-flights.{{refn|group=notes|name=J2fail|The J-2 had three premature in-flight shutdowns (two second-stage engine failures on [[Apollo 6]] and one on [[Apollo 13]]), and one failure to restart in orbit (the third-stage engine of Apollo 6). But these failures did not result in vehicle loss or mission abort (although the failure of Apollo 6's third-stage engine to restart ''would'' have forced a mission abort had it occurred on a crewed lunar mission).}}

===Space Shuttle (1981–2011)===
The [[Space Shuttle Solid Rocket Booster]], used in pairs, caused [[Space Shuttle Challenger disaster|one notable catastrophic failure]] in 270 engine-flights.

The [[RS-25]], used in a cluster of three, flew in 46 refurbished engine units. These made a total of 405 engine-flights with no catastrophic in-flight failures. A single in-flight [[RS-25]] engine failure occurred during {{OV|99}}'s [[STS-51-F]] mission.<ref name="P&WFS">{{cite web|url=http://www.pw.utc.com/products/pwr/assets/pwr_SSME.pdf |title=Space Shuttle Main Engine |publisher=Pratt & Whitney Rocketdyne |access-date=November 23, 2011 |year=2005 |url-status=dead |archive-url=https://web.archive.org/web/20120208191620/http://www.pw.utc.com/products/pwr/assets/pwr_SSME.pdf |archive-date=February 8, 2012 }}</ref> This failure had no effect on mission objectives or duration.<ref name="Hale">{{cite web|author=[[Wayne Hale]] & various|title=An SSME-related request|publisher=NASASpaceflight.com|access-date=January 17, 2012|date=January 17, 2012|url=http://forum.nasaspaceflight.com/index.php?topic=27783}}</ref>