Talk:Space Shuttle main engine

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Good article Space Shuttle main engine has been listed as one of the Engineering and technology good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Article milestones
Date Process Result
July 20, 2010 Peer review Reviewed
April 26, 2012 Good article nominee Listed
Current status: Good article
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Designation of the SSME as RS-24[edit]

SSME was originally designated as RS-24 according to Rocketdyne's own document, publication 573-A-100 New 9/99 "Liquid Propellant Rocket Propulsion Systems," page 26. RS-25 was a misnomer adopted early in the Ares program. The term RS-25 was used to refer to an expendable version of the SSME. However, it was later discovered that the designation RS-25 had already been given to a NTO/MMH thruster that was never fielded. By that time, it was too late to make the change, so RS-25 stuck. Technically the expendable SSME was going to be called the RS-24f, because it was going to be the 6th block upgrade (f). Attempts at editing the page have been rejected due to "uncited references." Sorry that a website can't be provided, but feel free to contact Boeing or Rocketdyne to request the publication requested above. <--- The above statement is wrong and so is the author calling it a "misnomer". According to Program Designations documents here at Rocketdyne from *1971* (~40 years ago!) the RS-24 was reserved for the Space Shuttle Auxilary Propulsion System (SSAPS) and that RS-25 was reserved for the Space Shuttle Main Engine (SSME). Please update the article as the SSME is the RS-25. —Preceding unsigned comment added by 192.54.250.11 (talk) 18:50, 13 May 2010 (UTC)

"SSME was designated the RS-24 for it's original and Block I configuration, RS-25 for the Block II configuration, which was used for the Ares proposals and new SD-HLV proposals" <--- Once again someone changed this and it is completely wrong! That is a TYPO in the Boeing article! As I mentioned earlier, according to Program Designations documents here at Rocketdyne from *1971* (~40 years ago!... way before that boeing article and the Block I) the RS-24 was reserved for the Space Shuttle Auxilary Propulsion System (SSAPS) and that RS-25 was reserved for the Space Shuttle Main Engine (SSME). Please update the article as the SSME is the RS-25. — Preceding unsigned comment added by 192.54.250.11 (talkcontribs) 17:32, 14 January 2011 (UTC)

I must agree with the above IP user's analysis regarding the RS-24 designation; the only other place I can find a reference to it related to the SSME is on the Astronautix page, which I can only assume is incorrect (possibly transferred from here to there) - Pratt & Whitney Rocketdyne refer to it solely as the RS-25, and no-one on the NSF forum appears to have heard of it either. As a result, I'm removing the reference to RS-24 until someone can provide a reliable source (preferably from the manufacturer) which supports it. Colds7ream (talk) 16:40, 23 November 2011 (UTC)

Rocket engine guidelines[edit]

(Discussion copied from Wikipedia talk:WikiProject Spaceflight)
Hi folks, just wondering if there's any thoughts as to what format the articles concerning rocket engines should take? I've been having a go at sorting out Space Shuttle main engine and have reshuffled it into an organisational structure I think should do the job, but there are no high-quality rocket engine articles (that I can see) to compare it to, and I have been unable to find any project-specified guidelines. I posted a similar request at WP:ROCKETRY but they're inactive - any help or suggestions would be appreciated! Cheers, Colds7ream (talk) 15:53, 30 November 2011 (UTC)

The way you have the article set up now is perfect! All that it needs is to be sourced, I don't know where you would get them or I would help. I think all rocket engine articles should follow the SSME article. I would add just one thing to the article to make it perfect though. I would include a write up (short, long or in between) of major incidents or failures. For the SSME's one would be the damage to the nozzle lines on STS-129 (I think it was STS-129). I hope that helps!--NavyBlue84 15:34, 7 December 2011 (UTC)
Thanks for the confidence boost! :-) Yep, I've been trying to gather a reasonable set of sources, which is proving to be quite a mission - surprisingly little is available as far as I can tell, although there were a couple that I found when formatting the few references that were already there. Hopefully once I've put this through the usual article appraisal mangle we can see if we can sort out a guideline for engines so we can work on the rest! :-S Colds7ream (talk) 15:43, 7 December 2011 (UTC)

GOCE copyedit January 2012[edit]

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Hi

During the copyedit a few things came to light that may need attention:

Components
  • "produce the thrust required to launch the spacecraft" - if this is true, why does the SS have to piggyback on a huge rocket tank with solid fuel boosters?
  • "Fuel and oxidizer" - I think it might be best to explain what these are here, it can be confusing to see oxidizer - many people will assume Oxgygen and Hydrogen are fuel.
  • "Fuel and oxidizer from the external tank entered the orbiter at the umbilical disconnects," -> "Fuel and oxidizer from the Space Shuttle external tank entered the orbiter at the umbilical disconnects," It was not clear that the SS was being discussed. Past tense is also a little confusing, though the SS is of course now retired. Any chance of some links, umbilical disconnect and fuel and oxidizer - though "Fuel (liquid Hydrogen) and oxidizer (oxygen) from ..." would suffice.
  • "at the umbilical disconnects" - these are not mentioned previously so we have no idea where or what these are. Are they from the gantry to the craft, from the gantry to the SS, or from the large tank that takes off to the craft?
  • "the pressure of which creates the thrust required to launch the spacecraft." -> "the pressure of which creates the thrust." Perhaps not necessary to repeat the launch part, as well as it being only part of the necessary thrust required to launch the spacecraft. Would it be appropriate to explain that the expansion of the ignition is what creates the pressure?
  • Right, I think I've made all these changes, see what you think! :-) SalopianJames - previously Colds7ream (talk) 09:37, 25 January 2012 (UTC)
Oxidizer system
  • "at approximately 28,120 rpm with a power of 23,260 hp." -> "at approximately 28,120 rpm, giving a power output of 23,260 hp." I was not sure if this was hp needed to drive the turbo or hp output. If it was needed to drive, then perhaps "at approximately 28,120 rpm, giving the necessary pump drive power of 23,260 hp."
Fuel system
  • "180 degrees from the LPOTP." Unclear to what this is referring. Could do with some explanation - is it 180 horizontally or vertically in relation to the LPOTP, or does this mean on the opposite side of the engine or SS structure?
  • "with a power of" - same as before
  • "remaining hydrogen passes between the inner and outer walls to cool" - inner and outer walls of what?
Preburners
  • "The augmented spark igniter was a small" - what is it now? If this is in the past tense because it relates to the retired SS, that needs to be mentioned, perhaps "On the Space Shuttle Orbiter," at the beginning of the section, or in the title of the section. If this is all concerning the SSO, as there is no info available on the SLS, it is even more important to include it.
  • "When an engine was operating, the main valves were fully open." - should this read, "When an engine was operating at full thrust, the ..."
Nozzle
  • "varied the angle of the nozzle, reducing it near the exit" - what angle? THe whole nozzle from vertical? to the vertical angle of the SSO? In the shape of the bell wall?
  • "The inner part of the flow" - flow of what? does this mean the exhaust gas or internal mixing?
Space Launch System
  • "engines at its aft, and an interstage structure at the top." - the SLS article doews not list an "interstage", should this be "upper-stage"?
General
  • Abbreviations - need the first use spelled out in full with abbreviation in brackets, for example; "Liquid Oxygen (LOX)". After this the abbreviation can be used.
  • gas -> gases: I have changed this in a lot of places, though I could be incorrect. My reasoning is that if hydrogen and oxygen are mixed, that is a gaseous mix of two gases; in particular, "fuel-rich" implies that there is fuel and a smaller quantity of something else.
  • Is it correct that the hot hydrogen is mixed with liquid oxygen in the MCC? The opening paragraph of the Preburners section states "The fuel and oxidizer enter the preburners and are mixed..." while the later paragraph states "and liquid oxygen and gaseous hydrogen flow into the main combustion chamber" - am I to understand from this that they are separate systems, that mixing in the preburner and mcc are H2 gas and LOX, and that the oxygen used in the pre-burner is in gaseous form?
  • Past tense - While I understand that much of the use of past tense may derive from the redundancy of the SSO, the issue is consistency. We cannot have "The main oxidizer valve and the main fuel valve control the flow of liquid oxygen and liquid hydrogen into the engine and were controlled by each engine controller. When an engine was operating, the main valves were fully open." - either they must all be past tense, and the engine not in use any more or in the future, or context must be applied (see note on adding "On the Space Shuttle Orbiter...").
  • OK, so, again, I think I've made all the relevant changes you suggested - the only excaptions are your comment about main valve opening and liquid/gas mizing in the MCC, as I double-checked the soirce and confirmed that that's what it says. Looking good? :-) SalopianJames - previously Colds7ream (talk) 20:20, 26 January 2012 (UTC)

Notes[edit]

A flowchart showing the flow of liquid hydrogen fuel through an RS-25 engine. See adjacent text for details.
Fuel
A flowchart showing the flow of liquid oxygen oxidiser through an RS-25 engine. See adjacent text for details.
Oxidiser
RS-25 propellant flow.

I have only edited the first part, as it is quite technical I need reassurance that it is indeed still correct. The fuel flow is still hard to follow, even when reading the explanation in tandem with the diagram. I cannot immediately see how that could be improved, though the diagram is a little vague on fuel routes after the main valve. If satisfactory, I will continue tomorrow. Chaosdruid (talk) 06:38, 25 January 2012 (UTC)

Thanks very much indeed for this, as far as I can tell, everything you've edited is still correct. As for the complexity, I entirely agree; its a very technical subject that's hard to follow, which is why it needed a copyedit so badly. One way of helping out with this might be the two flowcharts on the right, which show in a clearer manner exactly where the propellants flow; might help out in the detangling of the prose. Cheers, SalopianJames - previously Colds7ream (talk) 09:37, 25 January 2012 (UTC)
I think adding the flowchart is a good idea. It is difficult to ascertain flow from the red arrows on the 2D engine diagram, especially where it flows through the manifold and behind other pipes. Chaosdruid (talk) 19:12, 26 January 2012 (UTC)
I have put this on hold due to what appears to be material copied from the website [1] - while I appreciate there is some leeway given with NASA documents, the citation is "Information content from the NSTS Shuttle Reference Manual (1988)"
Can someone please confirm whether or not this is copyrighted by anyone or exists as free from copyright under governmental documentation rules? Thanks Chaosdruid (talk) 13:37, 3 February 2012 (UTC)
NASA material is in the public domain - see Template:PD-USGov-NASA and NASA's own guidelines. SalopianJames (talk) 13:50, 3 February 2012 (UTC)
My main concern is that there is a list of guidelines, two of which are:
  • "4. NASA should be acknowledged as the source of the material."
  • "5. It is unlawful to falsely claim copyright or other rights in NASA material."
This poses the problem of attribution. The material which has been taken directly from any NASA site, or handbook, must either be attributed as, without attribution, the copyright notices which Wikipedia places for the material to be used on other sites may well become invalid (as it may break guideline No. 5).
My question is not about NASA copyright policy, which I am familiar with, but whether or not there is correct attribution in the amount of material copied directly from those NASA documents. It seems that the ref [3] is used 16 times and I wondered if this was enough for those directly copied portions of text? It may be as simple as looking at them and saying yes or no, and if no, then putting some more No. 3s in. Chaosdruid (talk) 09:05, 5 February 2012 (UTC)
I have noted your addition of a general attribution in the form of {{Include-NASA}} Chaosdruid (talk) 09:12, 5 February 2012 (UTC)
OK, I have gone as far as I can - thanks for your patience, RL issues have made it impossible to do much editing this past week or so. GOod luck with the GA :¬) Chaosdruid (talk) 03:27, 12 February 2012 (UTC)
Thank you so much for your time an assistance - its very much appreciated! :-) SalopianJames (talk) 19:00, 13 February 2012 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

GA1[edit]

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

GA Review[edit]

This review is transcluded from Talk:Space Shuttle Main Engine/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Titoxd (talk · contribs) 00:47, 1 March 2012 (UTC)

I will be reviewing this article. Note that since the article is rather long, this review will take a bit of time to finish; I also will be not be able to reply between March 2 and March 4 due to IRL committments. Titoxd(?!? - cool stuff) 00:47, 1 March 2012 (UTC)

GA review – see WP:WIAGA for criteria

  1. Is it reasonably well written?
    A. Prose quality:
    Detailed comments:
    Lede
    • The engine produces a specific impulse (Isp) of 453 seconds in a vacuum … — This entire paragraph provides a plethora of performance specs, but it doesn't give context. The lay reader doesn't know whether 453 s of ISP is a good or bad figure for bi-propellant engines. Give a comparison to other engines in the RS-25's class.
    • While we are on the topic of ISP, PWR gives the specific impulse of the SSME as 452 s. The SSME article's infobox and Comparison of orbital rocket engines both give 452.3 s. 452.3 ≠ 453; please fix this, and do a quick check of all the other performance statistics listed in the article.
    • The engine is capable of throttling between 67% and 111% of its rated power level in one percent increments and operates at extreme temperatures, with the liquid hydrogen fuel being stored at −250 °C (−418 °F) while the temperature in the combustion chamber reaches 3,315 °C (5,999 °F), higher than the boiling point of iron. — run-on sentence, please split; the thermal extrema info can be easily put into a standalone sentence. Also, hyphenate "one percent", and link to combustion chamber.
    • Also on the last sentence: I am surprised we have thermocouples that are able of measuring how the temperature in the combustion chamber reaches exactly 5999 ˚F, and never reaches 6000 ˚F. :) Use the |disp=flip and |sigfig= arguments of {{convert}} to avoid these precision issues.
    • On the Space Shuttle, the RS-25 was used in clusters of three engines mounted in the aft structure of the Orbiter, with fuel being drawn from the External Tank. — you tend to use "orbiter" as a common noun everywhere except in the lede, so don't capitalize it here. Same with the external tank (but curiously, the ET is linked 4 out of the 5 times it is used in the article, so you also need to fix that overlinking.)
    • The engines were used for propulsion during the entirety of the spacecraft's ascent, with additional thrust being provided by two solid rocket boosters and sometimes the Orbiter's Orbital Maneuvering System. Do you need "sometimes" there?
    • On the Space Launch System (SLS), expendable versions of the engines will be used in clusters of up to five, drawing their propellant from the rocket's core stage. — awkward phrasing around "up to five": consider replacing it with On the Space Launch System (SLS), expendable versions of the RS-25 will be installed in the rocket's core stage, with different versions of the vehicle using three- or five-engine clusters. or something similar. Also, watch your tenses in this entire paragraph, since you switch from future tense to present tense in the middle.
    • with additional thrust coming from two solid or liquid-fuelled boosters — since we don't know what kind of boosters the later versions of the SLS will have yet, why not simply say with additional thrust coming from two auxiliary boosters?
    Components
    • Fuel (liquid hydrogen, or LH2) and oxidizer (liquid oxygen, or LOX) from the Space Shuttle external tank entered the orbiter at the umbilical disconnect valves — you only use LH2 and LOX twice each in the article, and all of those inclusions are in the same paragraph. I'd remove the abbreviation, since it simply isn't needed. A link to oxidizing agent would be useful here, although I'm not sure a link to fuel would be.
    • The entire first paragraph of the section lede needs a {{citation needed}} for the SLS information. The paragraph uses a 1998 STS press kit for its info, and there is no way it could have any SLS data inside of it.
    • Second paragraph needs extensive linking. To name a few, you need to link to heat exchanger and pogo oscillation. More importantly, this paragraph doesn't tell you why the oxidizer is split into four different pathways. There is plenty of information in staged combustion cycle that you could put here that would help the non-specialist reader make any sense of what is going on.
    • Third paragraph: This paragraph explains why the fuel has to go different pathways, which is good. Link the first instance of "nozzle", not the third.
  1. B. MoS compliance for lead, layout, words to watch, fiction, and lists:
  2. Is it factually accurate and verifiable?
    A. References to sources:
    B. Citation of reliable sources where necessary:
    C. No original research:
  3. Is it broad in its coverage?
    A. Major aspects:
    B. Focused:
  4. Is it neutral?
    Fair representation without bias:
  5. Is it stable?
    No edit wars, etc:
  6. Does it contain images to illustrate the topic?
    A. Images are copyright tagged, and non-free images have fair use rationales:
    B. Images are provided where possible and appropriate, with suitable captions:
  7. Overall:
    Pass or Fail:

Thanks for the review! :-) I made some improvements, more to follow. With reference to the specific impulse, P&W quotes 452.3 seconds here. SalopianJames (talk) 14:48, 1 March 2012 (UTC)

What's the status of this review? Nothing's happened in a month. Wizardman Operation Big Bear 15:53, 7 April 2012 (UTC)
The reviewer hasn't responded to the March 1 corrections: the only two edits by the reviewer on Wikipedia since writing the material on this page were on two templates for discussion on March 6. Nothing since, which is over a month. The nominator had modest activity in March after the first, and has no edits yet this month. BlueMoonset (talk) 05:48, 9 April 2012 (UTC)
I'm still here! Was waiting for responses, then my medical finals got in the way - I'm going to be abroad for the next three months too, so probably will have a tiny edit count, I'm afraid. SalopianJames (talk) 08:22, 9 April 2012 (UTC)
In that case I'll put it back in the queue for another reviewer to wrap up. Wizardman Operation Big Bear 13:50, 15 April 2012 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Titoxd (talk · contribs) 00:47, 1 March 2012 (UTC)

GA2[edit]

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

GA Review[edit]

This review is transcluded from Talk:Space Shuttle Main Engine/GA2. The edit link for this section can be used to add comments to the review.

Reviewer: GreatOrangePumpkin (talk · contribs) 09:34, 26 April 2012 (UTC)

GA review (see here for what the criteria are, and here for what they are not)
  1. It is reasonably well written.
    a (prose): b (MoS for lead, layout, word choice, fiction, and lists):
    nicely written
  2. It is factually accurate and verifiable.
    a (references): b (citations to reliable sources): c (OR):
  3. It is broad in its coverage.
    a (major aspects): b (focused):
  4. It follows the neutral point of view policy.
    Fair representation without bias:
  5. It is stable.
    No edit wars, etc.:
  6. It is illustrated by images, where possible and appropriate.
    a (images are tagged and non-free images have fair use rationales): b (appropriate use with suitable captions):
  7. Overall: Great article!
    Pass/Fail:

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

GreatOrangePumpkin (talk · contribs) 09:34, 26 April 2012 (UTC)

Sources supporting "fossil" nature of LH2?[edit]

Are there any sources supporting the notion that LH2 is a "fossil" fuel? If so, let's discuss them here before modifying the article to incorporate them. (An IP editor is repeatedly making this assertion, e.g. here.) (sdsds - talk) 07:30, 31 July 2013 (UTC)

NB See Methane reformer for an explanation of the process to which this editor is likely referring. (sdsds - talk) 08:08, 31 July 2013 (UTC)

Requested move[edit]

The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: page moved. Armbrust The Homunculus 09:23, 29 April 2014 (UTC)


Space Shuttle Main EngineSpace Shuttle main engine – Case normalize; commonly treated as generic in sources. See book n-grams (which shows majority lower case even though it also counts the many capitalized uses in titles, headings, and defining the acronym SSME). --Relisted. BrownHairedGirl (talk) • (contribs) 12:41, 21 April 2014 (UTC) --Dicklyon (talk) 04:11, 13 April 2014 (UTC)

  • Support move, as there is no reason to capitalize the common noun "main engine" here. - WPGA2345 - 21:37, 15 April 2014 (UTC)
  • Oppose this is NASA/Rockedyne's engine and they both capitalize.GliderMaven (talk) 22:33, 15 April 2014 (UTC)
  • Support: "main engine" is a common noun phrase. See also the reasoning in WP:SSF: MOS doesn't base it's style decisions on "official" documents that upper-case things to make them seem uniquely special.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  10:47, 24 April 2014 (UTC)
  • Support as per caps policy Red Slash 03:18, 29 April 2014 (UTC)
  • Support, per caps policy. N2e (talk) 05:02, 29 April 2014 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Wrong move[edit]

This is a proper noun, and the people that own the equipment always capitalise it. IT IS WRONG TO CHANGE THE CASE OF A PROPER NOUN IN TITLES, that's what the caps policy actually says, not that all words should be made lower case.GliderMaven (talk) 12:34, 29 April 2014 (UTC)

Agreed. Martijn Meijering (talk) 12:39, 29 April 2014 (UTC)

Requested move2[edit]

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the proposal was no consensus. --BDD (talk) 18:09, 21 May 2014 (UTC)

Space Shuttle main engineSpace Shuttle Main Engine – Although it was just renamed, and the move was bureaucratically performed more or less correctly, the problem is that the people !voting didn't seem to be aware that this is a proper noun, and as such the common words 'main engine' should be capitalised, just like when common words appear in a proper noun of a song or book title. Although many people may well capitalise this incorrectly, I'm finding that the owners and builders of the engine, and most people that write about SSMEs use uppercase. When I did a google, 19 out of the first 20 hits all have the engine name capitalised. The caps policy says:

Wikipedia:Naming conventions (capitalization):⋅

Do not capitalize the second or subsequent words in an article title, unless the title is a proper noun.

The 'Main Engine' looks strange, but is part of its name, it's a proper noun, it's not a descriptive article name. --Relisted. BrownHairedGirl (talk) • (contribs) 15:57, 8 May 2014 (UTC) --GliderMaven (talk) 00:23, 30 April 2014 (UTC)

[citation needed] Red Slash 03:47, 2 May 2014 (UTC)

The area under the blue curve on the N-gram graph is the number of published books that used the phrase 'Space Shuttle Main Engine', the red curve is 'Space Shuttle main engine' and the green curve is 'space shuttle main engine'. The blue curve outweighs all the others, even added together, by a factor of about 2; and it is still more popular than any of the others (but relatively few books are now being written on this engine).GliderMaven (talk) 14:57, 5 May 2014 (UTC)
That's bad ngram data, as it is not accounting for use in titles and headings and other capitalized circumstances. The ngrams have to limit the results to running text.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  23:26, 5 May 2014 (UTC)
  • Oppose – when we went through this before, the move proposal was presented with evidence. That's why it went as it did. The current proposal comes with nothing but a bald assertion that it's a "proper name". Evidence contradicts that. So leave it. Dicklyon (talk) 04:11, 2 May 2014 (UTC)
No, the evidence doesn't show that. In my book you actually lied in the previous review, Space Shuttle Main Engine is and apparently always has been the most popular name/N-gram used.[2]; you apparently added two different N-grams together to make it seem that lower case is more popular, but that search shows nothing like that. Other people can interpret your behavior as they like, but to me it seems you deliberately misrepresented these results to try to get the title changed.GliderMaven (talk) 14:39, 5 May 2014 (UTC)
I lied? I said Case normalize; commonly treated as generic in sources. See book n-grams (which shows majority lower case even though it also counts the many capitalized uses in titles, headings, and defining the acronym SSME). This is all true. You are suggesting that if I had omitted some of the lower case ones then I would have not been lying? Or what? I have not denied your claim, either, which is that the variant with all words capitalized has been the most popular. That completely misses the point though, which is that lower case main engine is more common, and that per WP's MOS:CAPS we would only capitalize it if it's consistently capitalized in sources. Even if there were only two variants, and the caps one were more popular, that would not necessarily meet the criterion for WP to treat it as a proper name. Dicklyon (talk) 03:25, 6 May 2014 (UTC)
  • Comment I'm generally for de-capitalisation, but I think there is ground for an exception here. Beyond NASA abbreviating it as "SSME", I think the analogy would be if BMW decided to call their next engine, instead of a string of numbers and letters like "S70/2", to call it the "BMW Car Engine". In such a case I don't think it would appropriate to title the article "BMW car engine", as it obviously could be confused with BMW car engines in general. Now the SS has only one type of engine, but the principle remains applicable: the capitalisation makes it clear it is a particular engine model. walk victor falk talk 11:56, 5 May 2014 (UTC)
  • Comment: @Victor falk: Acronyms are virtually always capitalized, regardless of the case of the words being abbreviated, so "NASA abbreviating it as 'SSME'" doesn't mean anything.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  23:26, 5 May 2014 (UTC)
  • @SMcCandlish:, I know an acronym is not a definitive case for capitalisation, that's why I only mentioned it in passing, but what about the analogy with BMW calling an engine model "BMW Car Engine"? Should wikipedia title the article BMW car engine? Why or why not? walk victor falk talk 12:08, 6 May 2014 (UTC)
  • @Victor falk: It's not a close analogy. The manufacturer's actual name for this engine is RS-25; "Space Shuttle Main Engine" is the client's designation for it, in that style of Official Capitalized Governmental Blather (OCGB) that WP is not under any obligation to adhere to. If BMW makes an engine called the XPFoo-99, and it gets used in [whatever, making up an example] Formula One racing, where the F1 organization decide to call it the New F1 Standard Powerplant, for their own internal reasons, WP should still call it the XPFoo-99, unless F1's designation become overwhelmingly the more common name. The only real differences here are that NASA's internal designation for the RS-25 happens to coincide except as to case with the real common name i.e. what external reliable sources call the thing, confusing the matter considerably, and some people wrongly fall for the idea that what NASA says is somehow "Official" in any way that WP cares about because they are a government agency, which is an argument to authority fallacy and simplistic legalism. A WP:OFFICIALNAME argument would put this at RS-25. A WP:COMMONNAME argument put it at Space Shuttle main engine, because sources do mostly capitalize Space Shuttle but usage is very divided on capitalizing the rest, and we lower-case by default (as does Chicago Manual of Style and other modern style guides, almost invariably). If the manufacturer had named it the Space Shuttle Main Engine, not the RS-25, that would be a different case.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  22:11, 6 May 2014 (UTC)
  • Support – On spaceflight forums I visit aerospace professionals use the term SSME, which suggests it's a proper name. Martijn Meijering (talk) 23:14, 5 May 2014 (UTC)
  • Comment: @Mmeijeri: It does not suggest that, though. Acronyms are virtually always capitalized, regardless of the case of the words being abbreviated. Government agencies abbreviate and acronymize just about everything; it's not encyclopedic style and doesn't tell us anything about proper names.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  23:26, 5 May 2014 (UTC)
  • Oppose: I'm doing my own ngrams. The first uses "the Space Shuttle Main Engine,the Space Shuttle main engine,the space shuttle main engine"[3] By using a very (surely the most) common lower-case lead-in word, "the", we eliminate false hits on titles and headings, that skew the data toward capitalization. It shows that the two lower-case "main engine" versions together have historically about equaled the capitalized version (with spikes in both directions, e.g. preference for capitalization in the early 1980s and early 1990s, but for lower case in the late 1980s). Since the early 2000s, lower case has consistently actually exceeded the capitalization's frequency. Doubtless, many uses are referring to the main engine of the space shuttle (or the Space Shuttle if you're convinced that's a proper noun) in a general sense; they're talking about what make the shuttle go, in a vague way. Other sources may be treating it more technically, as a specific Rocketdyne engine model. However, we know that its real (i.e. proper name) engine model designation is RS-25; "Space Shuttle Main Engine", however you case it, is a stand-in for it. The [S|s]pace [S|s]uttle main engine is what most sources call it, varying depending on whether they treat the vessel series as a proper name, but not the engine itself. The capitalization heyday of the engine is long since over (and was probably skewed toward capitals by official NASA press releases and other publications being quoted verbatim; this probably also explains the sharp trend toward lower case over the last 10+ years). We can also demonstrate with another ngram[4], "Space Shuttle's Main Engine,Space Shuttle's main engine,space shuttle's main engine", that "main engine" is usually not capitalized in this context, but, incidentally, "Space Shuttle" is. Anyway, NASA itself likes to call the RS-25 the "Space Shuttle Main Engine" (SSME), but we know that government agencies love to capitalize everything they have a part number for ("Meals, Ready to Eat" or MRE, etc.), so this is totally meaningless to WP. My conclusion is that the RS-25 is the proper name of this engine and would be capitalized even if it were not some kind of acronym, but that "Space Shuttle Main Engine" is a NASAism, with "Space Shuttle main engine" being the most sensible article title, if we accept that Space Shuttle (in ref. to the specific series of NASA vessels, not shuttles to space generally) is capitalized.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  23:26, 5 May 2014 (UTC)
  • Oppose moving back. A main engine for the Space Shuttle will still be a "Space Shuttle main engine" even if there is a particular model formally titled "Space Shuttle Main Engine," and even if that particular model is the only one made. - WPGA2345 - 18:19, 9 May 2014 (UTC)
  • @SMcCandlish: comment on both your reply & your !vote. First I agree 100% about wp:officialname, if we choose to call it SSME, it should be witout regard for NASA's preferences and for our own reasons. To whit, as a service to our readers to minimise potential confusion (Curse them faceless bureaucrats for choosing maximally bland designations!). About the seller and buyer using different designations, it doesn't change the fundamental problem; if BMW sells its XPFoo-99 engine to Marlboro-McLaren for Formula 1 racing, we still have a problem if Marlboro-McLaren decided to call it the "Formula One Engine", and that Formula One engine (Dummy link. Case in point: it redirects to "Formula One engines") would mislead people into thinking the article is about all Formula 1 engines. What is a "space shuttle main engine" after all? We don't have Saturn V main engine, because there is really is no such thing (or perhaps that would be all the first stage Rocketdyne F-1 engines together ), and the space shuttle is nothing but a rocket with wings. So its main engine consists of three Space Shuttle Main Engines. As you rightly point out, ngrams are inconclusive, both for the reasons you state and because it's never clear when S/space S/shuttle M/main E/engine refers to the individual RS-25/SSME, or to the primary propulsion of the three of them together (in contrast with the secondary propulsion of the SRBs).
    Considering all that, I wonder if it wouldn't be better to title it RS-25, by analogy with Rocketdyne F-1, as the article is about the individual engines and not the equivalent of the Saturn V first stage. walk victor falk talk 14:37, 19 May 2014 (UTC)
    Sounds like a grand idea to me, especially given the additional complications you outline.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  14:56, 19 May 2014 (UTC)
Well then, I supposed this move discussion should be closed and a move request to RS-25 made. walk victor falk talk 17:35, 19 May 2014 (UTC)
The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Requested move3[edit]

The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: Not Moved per original close of @Jenks24 on 18 Jun. The previous close should not have been reverted with prior consent of Jenks24. This article is moved protected for 30 days and another requested move should not be initiated for 6 months, unless a move review determines otherwise. Mike Cline (talk) 14:14, 22 June 2014 (UTC)



Space Shuttle main engineRS-25 – Per the Requested move2 discussion above, especially the exchange between SMcCandlish and me. --Relisted. walk victor falk talk 09:13, 18 June 2014 (UTC) walk victor falk talk 20:17, 21 May 2014 (UTC)

Isn't RS-25 the name of the new SLS engine? Wasn't RS-24 the SSME? Martijn Meijering (talk) 21:23, 21 May 2014 (UTC)
  • Oppose. I prefer to keep this as a more common name, not change it to an ambiguous abbreviation or technical name like "RS-25". I also see in that previous discussion there was a reference to the Rocketdyne F-1 article, but at least that title is a bit more clear. I also do not see evidence that "RS-25" commonly and specifically refers to the space shuttle engine; per a Google search. I also get in the top 20 results products and items other than the engine.[5] Zzyzx11 (talk) 04:22, 22 May 2014 (UTC)
The thing is, as the Space Launch System is coming online, the term "space shuttle main engine" is becoming more and more antiquated. The SLS raison d'être is that it recycles space shuttle technology as much as possible, and therefore has functionally identical engines. As for other stuff called rs25, it doesn't matter as long as they don't have a wiki article that can be considered more of a wp:primarytopic than the shuttle engine. walk victor falk talk 05:10, 22 May 2014 (UTC)
  • Oppose per z11. The SLS does not use the SSME (except for the prototypes), they will use a derivative. -- 65.94.171.126 (talk) 05:36, 22 May 2014 (UTC)
Even if the Space Launch System was to formally announce the name of an official future "derivative" of the Space Transport System engine (the name similarity between the two spacecraft projects is no coincindence), the wikipedia article would most certainly treat them as members of the same family, as it does with other closely related technical devices. walk victor falk talk 18:14, 10 June 2014 (UTC)
  • Comment It seems the lede of the article is erroneous, and that the RS-24 is the engine of the old space shuttle. The SLS article says the "RS-24D/E" is its the engine, sourced with a NASA fact sheet; this chimes in with the comments above, that the RS-25 is not yet operational. If so, the move request should be to RS-24. I have tagged the lede with {{cn}}, and see what how this issue is resolved. walk victor falk talk 11:23, 22 May 2014 (UTC)
  • Comment: If there are two different space shuttle engines, that's a need for an article split. Regardless, this RM can't proceed until the factual matter is resolved, so I'm disabling the RM tag.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  02:25, 23 May 2014 (UTC)
  • Comment: No, it's the RS-25. The SLS article lists it as RS-25 so I'm not sure what article Victor falk is reading. See the discussion at the very top of this page for details, and this NASA factsheet. SalopianJames (talk) 14:13, 25 May 2014 (UTC)
That's correct, I apparently misread the infobox. Good news then, the move request can proceed with the uncertainty about rs24 dispelled. walk victor falk talk 12:36, 26 May 2014 (UTC)

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  • Comment: the current lede ("The RS-25, otherwise known as the Space Shuttle Main Engine (SSME), is a liquid-fuel [...]"), has been stable since January 2012 [6]. walk victor falk talk 18:14, 10 June 2014 (UTC)
  • Oppose. RS-25 is jargon, recognizable only to readers already familiar with the details. --SmokeyJoe (talk) 13:36, 17 June 2014 (UTC)
  • Comment. I closed this as not moved and was reverted by Victor falk (talk · contribs). It's been listed for over three weeks and not one single person has agreed with him and three have explicitly opposed. There is no chance of this RM ending in a moved result. I'd restore my close except I really can't be bothered arguing about this so I guess this can clog up the RM list for at least another week until another admin comes to the same conclusion. For future reference, Victor, "I was just about to relist" is a not a good enough reason to revert a close by an independent admin, especially when you are the proposer and only supporter of said RM. Jenks24 (talk) 09:29, 18 June 2014 (UTC)
@Jenks24:I had just notified relevant wikiprojects like WP:SPACEFLIGHT AND WP:ROCKETRY, and had forgotten to relist when I was done with that. This is a rather important article, that is GA-rated, and it shouldn't have such a poor mindlessly chosen title that doesn't reflect well on its otherwise excellent quality. The momentum in the discussion was lost because of the RS-24/RS-25 quibble, which led to the discussion being de-listed while the issue was being adressed [7] two days after the original nomination, so it hasn't clogged the RM for three weeks, but is a de facto old-week nomination. walk victor falk talk 10:08, 18 June 2014 (UTC)


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  • For the benefit of editors of notified wikiprojects, here's the last part of the previous discussion where the proposition to rename the article came up:
  • @SMcCandlish: comment on both your reply & your !vote. First I agree 100% about wp:officialname, if we choose to call it SSME, it should be witout regard for NASA's preferences and for our own reasons. To whit, as a service to our readers to minimise potential confusion (Curse them faceless bureaucrats for choosing maximally bland designations!). About the seller and buyer using different designations, it doesn't change the fundamental problem; if BMW sells its XPFoo-99 engine to Marlboro-McLaren for Formula 1 racing, we still have a problem if Marlboro-McLaren decided to call it the "Formula One Engine", and that Formula One engine (Dummy link. Case in point: it redirects to "Formula One engines") would mislead people into thinking the article is about all Formula 1 engines. What is a "space shuttle main engine" after all? We don't have Saturn V main engine, because there is really is no such thing (or perhaps that would be all the first stage Rocketdyne F-1 engines together ), and the space shuttle is nothing but a rocket with wings. So its main engine consists of three Space Shuttle Main Engines. As you rightly point out, ngrams are inconclusive, both for the reasons you state and because it's never clear when S/space S/shuttle M/main E/engine refers to the individual RS-25/SSME, or to the primary propulsion of the three of them together (in contrast with the secondary propulsion of the SRBs).
    Considering all that, I wonder if it wouldn't be better to title it RS-25, by analogy with Rocketdyne F-1, as the article is about the individual engines and not the equivalent of the Saturn V first stage. walk victor falk talk 14:37, 19 May 2014 (UTC)
    Sounds like a grand idea to me, especially given the additional complications you outline.  — SMcCandlish ¢ ≽ʌⱷ҅ʌ≼  14:56, 19 May 2014 (UTC)
Well then, I supposed this move discussion should be closed and a move request to RS-25 made. walk victor falk talk 17:35, 19 May 2014 (UTC)

Which was done in due course, until the unfortunate RS-24 hiccup derailed the process. I hope the exchange between me and SMcCandlish why the current title is inappropriate. walk victor falk talk 12:25, 18 June 2014 (UTC)

  • Oppose "Space Shuttle main engine" is the common name, reasonably well-known to the general public. "RS-25" is specialized jargon, well known only to those with technical expertise. Also, as a matter of process, an involved editor should not revert an administrative close, even if the RM has a spotty history. Xoloz (talk) 16:12, 18 June 2014 (UTC)
@Xoloz:, what do you suggest I do? Procedurally close myself and immediately ask for a move review? I find it frustrating that while the original move basically was "Moscaps!! Agree! Agree!" (and immediately contested), all those mishaps and delays are having a chilling effect on a serious conversation. walk victor falk talk 20:56, 18 June 2014 (UTC)
Now that the revert of the close has been completed, and Jenks24 has allowed it, I don't believe you should do anything. At this point, it is least disruptive to let the RM continue. However, in an ideal world, one wouldn't have reverted the close; but, one would simply have waited a month and posed a new RM. As proposer, this would have worked to your advantage by giving you a clean slate. Note that my opposition is not simply procedural. I would not have commented at all had I not concluded that COMMONNAME favors the status quo. My comment on procedure was an aside. Xoloz (talk) 16:51, 19 June 2014 (UTC)
In retrospect, xoloz, I should have immediately procedurally closed and re-nominated, I mulled over doing that but didn't want to seem derailing the process, so I just let it be closed normally. Oh well, twenty twenty and all that. Regarding wp:commonname, I'd like to stress that if RS-25 is not deemed wp:commonnameish enough, then the alternative is to return it to the original Space Shuttle Main Engine, where it was before before the routine and ill-considered wp:moscaps decapitalization. walk victor falk talk 14:06, 20 June 2014 (UTC)



  • Comment: Speaking as one of the primary authors of this article, I would say that at the moment the article title is in a bit of limbo. During the operation of the Space Shuttles the engine was indeed most commonly called the Space Shuttle M/main E/engine, and I strongly suspect that once the Space Launch System starts to fly it will be most commonly be referred to as the RS-25 as it has been on most internal SLS documentation from NASA so far (indeed, increasingly so). At the moment, however, it could be either, and so I would suggest leaving it at Space Shuttle M/main E/engine until SLS begins in earnest as the tide will probably turn very much in the direction of RS-25 and it could be renamed then? SalopianJames (talk) 13:53, 19 June 2014 (UTC)
  • Move to Rocketdyne RS-25. This is a rocket engine and should use the same article naming convention we have adopted for other rocket engines. If readers are unfamiliar with the name and go looking for "SSME" or "Space Shuttle main engine", that is what redirects are for. — Cheers, Steelpillow (Talk) 10:19, 20 June 2014 (UTC)
  • I agree with Steelpillow, Rocketdyne RS-25 makes the most sense. It follows the consensus of other rocket engine article names, it makes more sense than the bare alphanumeric designator, and -- sadly -- SSME has become outdated. —Elipongo (Talk contribs) 02:34, 22 June 2014 (UTC)
  • Support Though you'll see them referred to both as SSME and RS-25 within NASA documents over the years, the switch to the RS-25 name is well underway. Recent communication on SLS uses RS-25 as the primary name and mentions that they are from the STS program (example: http://www.nasa.gov/pdf/664158main_sls_fs_master.pdf). NASA designed and built these engines, Wikipedia should look to NASA's usage for guidance on article naming.--RadioFan (talk) 03:36, 22 June 2014 (UTC)
    On a point of fact, NASA did not build these engines, Rocketdyne did. — Cheers, Steelpillow (Talk) 10:29, 22 June 2014 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Page Name Change[edit]

Since these engines are now being tested for the Space Launch System, it might be appropriate to change the name of the page to RS-25. — Preceding unsigned comment added by Mnethercutt (talkcontribs) 13:12, 11 January 2015 (UTC)

Don't suggest that. Space-nazis will get upset and ban you. — Preceding unsigned comment added by 203.152.114.160 (talk) 03:16, 14 August 2015 (UTC)

Meaning of E designation for RS-25E[edit]

An editor citing a source appears to have interpreted the source to be saying that the E in RS-25E literally stands for "Expendable". But revisions of aerospace hardware rarely have such terms attached as initialisms, and E is also the very next letter following the existing RS-25D. I find the assertion very dubious, if mostly harmless. I'm fairly sure E just means "comes after D", and I don't feel the source supports the other interpretation. -:-  AlpinWolf   -:- 23:06, 16 August 2015 (UTC)

External links modified[edit]

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