Talk:RL10

Requested move
RL-10 (rocket engine) → RL-10 – Unnecessary disambiguation -- GW_SimulationsUser Page 11:09, 26 August 2006 (UTC)
 * It was moved, . —Centrx→talk &bull; 02:51, 7 September 2006 (UTC)

Blue Origin, speculation - removed
I know of no reason to believe Blue Origin might be using RL-10s, or even any similar engine. Everything I've heard (including the WP article) says they use HTP and RP-1 (or other kerosene). That and weasel words ("It is not known if...") justify removal of the comment, imho. I think it should be replaced only if there is a reputable current reference. Evand (talk) 15:03, 28 December 2008 (UTC)

Highest Isp of any chemical rocket engine
There is an assertion in Rocket Propulsion Elements, by George Paul Sutton and Oscar Biblarz that the RL10B-2 delivers the highest specific impulse of any chemical rocket engine. (p. 224). If this is correct it should be mentioned prominently in the lede of the article. One source shows 464 sec. This is presumably due in large part to the 285:1 nozzle expansion ratio, yes? (sdsds - talk) 07:06, 4 September 2009 (UTC)


 * If correct, I concur. (My copy of Sutton isn't handy at the moment, and p 224 isn't in the Google Books preview.)  However, it needs to be qualified appropriately.  Higher Isp has been achieved in testing (Li-F2-H2 tripropellant has reached 546 seconds).  I suspect the correct qualifier is highest Isp of any flight engine. Evand (talk) 22:13, 6 September 2009 (UTC)

Copyright problem
This article has been reverted by a bot to as part of a large-scale clean-up project of multiple article copyright infringement. (See the investigation subpage) This has been done to remove User:Accotink2's contributions as they have a history of extensive copyright violation and so it is assumed that all of their major contributions are copyright violations. Earlier text must not be restored, unless it can be verified to be free of infringement. For legal reasons, Wikipedia cannot accept copyrighted text or images borrowed from other web sites or printed material; such additions must be deleted. Contributors may use sources as a source of information, but not as a source of sentences or phrases. Accordingly, the material may be rewritten, but only if it does not infringe on the copyright of the original or plagiarize from that source. Please see our guideline on non-free text for how to properly implement limited quotations of copyrighted text. Wikipedia takes copyright violations very seriously. VWBot (talk) 05:56, 10 December 2010 (UTC)

This article has been reverted by a bot to as part of a large-scale clean-up project of multiple article copyright infringement. (See the investigation subpage) This has been done to remove User:Accotink2's contributions as they have a history of extensive copyright violation and so it is assumed that all of their major contributions are copyright violations. Earlier text must not be restored, unless it can be verified to be free of infringement. For legal reasons, Wikipedia cannot accept copyrighted text or images borrowed from other web sites or printed material; such additions must be deleted. Contributors may use sources as a source of information, but not as a source of sentences or phrases. Accordingly, the material may be rewritten, but only if it does not infringe on the copyright of the original or plagiarize from that source. Please see our guideline on non-free text for how to properly implement limited quotations of copyrighted text. Wikipedia takes copyright violations very seriously. VWBot (talk) 12:59, 10 December 2010 (UTC)

CECE efficiency
It is worth noting that in the picture of the CECE you see ice forming at the nozzle edge. This naturally has a negative impact on efficiency —Preceding unsigned comment added by 71.178.199.89 (talk) 17:07, 21 February 2011 (UTC)

Date issue for first flight of Centaur and RL10
There seems to be an inconsistency between this article and Centaur (rocket stage) as to the first flight date. The first Centaur flight was in 1962, but it was unsuccessful; this article gives a first flight date of 1963. I see no evidence that the first Centaur flight used a different engine type, so there seems to be a bit of an issue here. Mangoe (talk) 13:23, 13 December 2011 (UTC)

Rocketdyne vs Pratt & Whitney
The article currently states that the engine was developed by Rocketdyne. This is not the case - it was developed by Pratt & Whitney in the 50s, when Rocketdyne was its rival, being owned by North American Aviation. Pratt & Whitney then bought Rocketdyne, but this does not mean that Rocketdyne developed the engine, as it was already in production before P&W purchased Rocketdyne. A more accurate way to state the situation in the article would be 'developed by Pratt & Whitney and currently manufactured by Rocketdyne'. SalopianJames (talk) 12:47, 26 February 2012 (UTC)


 * I just reverted such a change again. The RL10 was a Pratt & Whitney produnct, not Rocketdyne. - BilCat (talk) 00:59, 4 December 2014 (UTC)

Edit warring by 99.194.201.73
This user has been reinserting badly sourced material and partially unsourced WP:OR material over the objections of other editors without engaging on the Talk page first, as requested, and as per WP:BRD. The edit-warring has been happening both here and over at RL60. Some of the proposed material can no doubt be added to the page, but it needs better sourcing and a consensus first. Martijn Meijering (talk) 16:34, 4 December 2014 (UTC)

Inconsistent data : dates, nozzle ratios, Isp, diameter
The summary box lists the first flight as 1962, the introduction gives 1961, & History has 1962. The summary lists nozzle ratios of 84:1 & 280:1 but the variant table gives 84:1 & 250:1 (note that this will change once the RL10C-1 is launched). The summary gives the Isp as 450 to 465.5 (said in the notes to be for the RL10B-2), Improvements & Specifications give 464, & the variant chart has 462. The summary & variant chart give the diameter as 2.13 m (7 ft 0 in) while Specifications gives 87 in (2.21 m). I'm not sure of this, but the photo of the second stage of a Delta IV Medium looks like it might be missing the nozzle extension. 69.72.92.87 (talk) 06:56, 6 December 2014 (UTC)

Also, the diameter of the RL10C-1-1 version is given in the table as 1.57 m (4 ft 9 in) but 1.57 m is over 5 ft. 96.88.198.77 (talk) 02:59, 1 November 2019 (UTC)


 * Any fixed yet, or Has anyone checked these against the references given ? I'll try to start next time I come by. (Commenting to delay archiving) - Rod57 (talk) 06:33, 8 January 2024 (UTC)

What is the approx price
Since cost prompted a search for alternatives: What was the approx cost of an RL10A or RL10B in 2012 ? - Rod57 (talk) 12:34, 10 January 2018 (UTC)
 * suggests they are about $17 million each ! - Rod57 (talk) 04:31, 16 January 2018 (UTC)

Picture caption refers to Saturn "kerosene burning rocket engines" - fixed
The first (at the moment) picture caption on the main page is "An RL10A-4 engine in London's Science Museum", but when the picture is clicked on and viewed by itself, the caption "Eight of these kerosene burning rocket engines loft the first stage of the Saturn 1 and 1B launch vehicle. LOX is the oxidiser" appears. 'Kerosene burning' presumably should instead be 'hydrogen burning'.

Jwpat7 (talk) 16:18, 27 January 2018 (UTC)


 * In fact the entire caption is wrong as it appears to be referring to a different engine entirely; the H-1 engine, of which there were eight on the first stage of Saturn 1 and 1B. The image is not an H-1. ChiZeroOne (talk) 18:11, 27 January 2018 (UTC)


 * Seems fixed now. Click on image now shows "6 of these liquid hydrogen burning rocket engines loft the second stage of the Saturn 1 and 1B launch vehicle." - Rod57 (talk) 06:45, 8 January 2024 (UTC)

Improvements?
The sections in the history section on improved versions appear to be outdated, as they describe a bunch of projects which started some years back but whose conclusions are never discussed. Probably most of the successor projects have the same issue. Can these be brought up to date? Mangoe (talk) 00:30, 19 June 2020 (UTC)

Launch anomalies
One RL10B-2 on a Delta IV M+ 2nd stage centaur, had a thrust anomaly on USA-239 GPS launch in 2012. It seems there was a fuel leak into the combustion chamber.. Worth noting ? - Rod57 (talk) 09:42, 21 July 2020 (UTC)

RL10A-4-2 really retired? - No, active on Atlas V May 2022
ULA says they're using the RL10A-4-2 on the Centaur upperstage for their test launch of the Starliner (potential crew capsule for ISS trips) today, 19-May-2022, yet it's listed here as "retired." I don't see a source for the retired label and maybe this is a pair of old engines they had lying around, so I didn't want to change the main article, but it does make me question whether that's accurate or not.

See |ULA: ATLAS V TO LAUNCH STARLINER OFT-2 "The Atlas V configuration for this mission is powered by dual RL10A-4-2 engines, each producing 22,600 lbs (100.5 kilo-Newtons) of thrust." Sp30305 (talk) 19:18, 19 May 2022 (UTC)


 * Seems fixed, now says Active (Centaur SEC, Centaur DEC). But maybe all later Atlas V Centaur will use different version RL10C-1. - Rod57 (talk) 07:17, 8 January 2024 (UTC)
 * The Kuiper flight also used an A-4-2. We know Starliner DECs will all have A-4-2s and it's looking more likely for Kuiper launches. That'd take A-4-2 use all the way to the end of Centaur III. Sub31k (talk) 07:59, 8 January 2024 (UTC)


 * More generally when is something "retired" ? When they stop marketing/selling it ? When they stop building them ? When they have no flyable examples left in stock ? when the last one built has flown (that was used for the space shuttle retirement in 2011) or been scrapped ? - Rod57 (talk) 06:53, 8 January 2024 (UTC)

Inconsistent data with respect to L3Harris Tech
@Mfb@Lazaro Fernandes@AmigaClone@Ergzay@Rod57 anyone of you know about RL-10 engine. If yes, please come forward and fix this issue raised by Tim Dodd on Twitter

https://x.com/Erdayastronaut/status/1744083615619699030?s=20

I am feeling shy of falling into controversies if i edit this famous engine's page. (He summons us to correct this) Thanking in advance, RIP B1058 (talk) 20:17, 7 January 2024 (UTC)


 * I don't know much about the RL-10, sorry Lazaro Fernandes (talk) 22:32, 7 January 2024 (UTC)


 * Sad that Tim Dodd didn't say which data of which RL10 model didn't match. Every row on the WP table has sources, so what do we do if the old sources disagree with L3H's latest summary? Maybe L3H are trying to rewrite history. But we'd need a reference to a reliable source, even a URL to the image that Tim Dodd posted. - Rod57 (talk) 06:23, 8 January 2024 (UTC)
 * Or maybe L3H has increased the characteristics of engines RIP B1058 (talk) 07:55, 8 January 2024 (UTC)
 * Thats why i forbade editing directly to avoid controversy RIP B1058 (talk) 07:56, 8 January 2024 (UTC)
 * Am I going mad? I have looked up and down in the table and on the AJR page to try and find discrepancy, and only found an erroneous value of mixture ratio for RL10C-1. What's the "very far off" thing he's complaining about for modern RL10? Genuinely confused. Sub31k (talk) 08:14, 8 January 2024 (UTC)
 * Many like thrust of RL10B-2 thrust by us is 24800lbf and L3H says 24750lbf RIP B1058 (talk) 08:22, 8 January 2024 (UTC)
 * That's a rounding error - the Cvt template is being used with metric units provided... somewhere? Delta PUG? that evaluate to, 24750 lb-f. Rounds to 3 sig figs though. I'll go change it - that's "very far off" though, is it? Sub31k (talk) 08:30, 8 January 2024 (UTC)
 * If we add precise ones like 92.45 instead of 92.5 this may go i think as he not an editor to know this rounding flaw is auto Generated.@Sub31k RIP B1058 (talk) 08:53, 8 January 2024 (UTC)
 * Not sure what you mean, but the correct way is to 1. ensure that all Cvt use the original unit (in many cases US Customary) as input and 2. correct with rounding parameters in the template. Sub31k (talk) 09:04, 8 January 2024 (UTC)
 * Thats right do it RIP B1058 (talk) 09:09, 8 January 2024 (UTC)