Talk:Compound steam engine

renaming and expanding article
Why was this article renamed without discussion on this page? I see a large amount of text has been added regarding other forms of steam engine compounding, and I'm not sure personally whether that would have been better in a separate article. Certainly the issue should have been discussed first. --Michael Johnson (talk) 10:31, 18 May 2008 (UTC)


 * I've been trying to precipitate re-structuring of the steam engine article, which should be the parent for many others. I had suggested that there should be an article on the compound steam engine in general, to take over some of the functions of compound locomotive, and act as a parent that could be referred to from other articles (traction engine, and steam boat, for example, neither of which logically link to compound locomotive). There was a large and comprehensive section on the subject within steam engine, and my suggestion was that the detail could be moved 'here', allowing the original article to be slimmed-down.


 * I confess I have not examined the edits yet (not much time at present), but my idea was that compound locomotive would remain as an article, but covering solely railway locomotives -- the history and general principles being moved to the parent compound engine (or compound steam engine) article). I am not knowledgeable about the subject, which is why I have had to leave it to others to implement. If there is consensus that we need two articles (general + loco) perhaps someone can 'do the necessary'? (I am in enough trouble for trying to sort out the steam engine article, which has needed restructuring for two years judging by the talk page comments.)
 * EdJogg (talk) 09:53, 19 May 2008 (UTC)


 * I agree wholeheartedly with your suggested arrangement. The history of this article is apparent in its bias towards railway practice, so strong that perhaps a separate article for locomotives is warranted to give full rein to the railway lobby while maintaining a more balanced general (and perhaps more scientific) approach here. Globbet (talk) 18:00, 20 August 2008 (UTC)


 * I'm also inclined to undo this move. There is really no discussion of compounding here, other than to do with locomotives, that isn't essentially duplicative of the material in steam engine. There's simply a lot more to say about locomotives because the application has design constraints that, in the end, made most types of compounding unsatisfactory-- though nearly everyone tried it. I can't really help with the non-locomotive material, but maybe that's the point. Maybe fixing up steam engine will give a better map as to how to deal with the marine and industrial engines. Mangoe (talk) 15:31, 29 October 2008 (UTC)

scope of article
This article is heavily concerned with railway locomotives and has far too little about compounding in stationery engines and nothing about marine engines. I have just expanded he Cornish engine article based on two recent articles by Alessandro Nuvolari and Bart Verspagen, but feel that I have reached the limit of my understanding. I have tagged the secion on Hornblower and Woolf as a "section-stub". It would be good if some one could deal with these issues. I will probably not be able to. Peterkingiron (talk) 14:51, 15 August 2009 (UTC)

Split
Now two articless.--ClemRutter (talk) 09:11, 11 October 2009 (UTC)

Interwiki links
A bot has just added a raft of interwiki links. Most of these actually relate to Compound locomotive, although the French, Dutch, and Russian articles (and the Swedish, at a pinch) cover more than just railway locos and are hence OK. To resolve this will require the links at the far end to be adjusted (when someone has the time...) The same adjustments will be needed at Compound locomotive.

EdJogg (talk) 13:33, 12 October 2009 (UTC)

expansion,cutoff and compound
expansion,cutoff and compound are mixed up in the article. high pressure cilinder does not exhaust into the atm. in a compuond engine. Wdl1961 (talk) 14:24, 13 October 2009 (UTC)


 * I have established a structure- and cleaned a lot of the dross- attempted to make it readable. I have left the history section as a list with extra work needed. I am more than happy to bow to expert knowledge and ce's. Steam engine and History of the steam engine are in need of attention.--ClemRutter (talk) 16:27, 13 October 2009 (UTC)
 * the "single expansion" takes care of it but feel free to rewrite. I try to stick to technical details i feel are obscure or inaccurate. Wdl1961 (talk) 18:50, 13 October 2009 (UTC)

Hatnote
ISTM that someone could well come to this article looking for information on turbo-compound engines. With this in mind I added a hatnote which has now been reverted.

In that we are a general encyclopedia seeking to provide information to any who seek it, I'm afraid I think this leaves a not too serious but completely needless gap in our navigation. Compound engine may not be the correct technical name for a turbo-compound engine, but it's a natural one for people who may have seen the Detroit Diesel "fifty free horsepower" advertisements or similar and are not expert in the field. Yes I know this one explicitly says "turbo compound" but the enquirer doesn't necessarily have the advert in their hand.

IMO a hatnote or something similar should be provided. Andrewa (talk) 11:59, 6 December 2012 (UTC)


 * This was yet another of your utterly ignorant additions, where you've seen two similar words and assumed that they implied two similar concepts. Please desist, or at least limit your additions to subjects where you've made at least some effort to learn about the subject beforehand. Andy Dingley (talk) 12:46, 6 December 2012 (UTC)


 * Rubbish. My research is at least as good as yours. Your analysis of my thought processes is laughable. Please desist, or at least limit your additions to subjects where you've made at least some effort to learn about the subject beforehand. Andrewa (talk) 20:20, 6 December 2012 (UTC)


 * Would a better clarification here be to rename to Compound steam engine? Andy Dingley (talk) 12:55, 6 December 2012 (UTC)
 * Surely you don't mean that my utterly ignorant addition was at least helpful enough that something should now be done in its place? Andrewa (talk) 16:01, 6 December 2012 (UTC)

Rename to compound steam engine

 * Compound engine → Compound steam engine ([ move]) – Better canonical name, and there's no overlap with this article scope and any other sort of "compound engine". Andy Dingley (talk) 13:12, 6 December 2012 (UTC) Andy Dingley (talk) 13:12, 6 December 2012 (UTC)
 * Done. Tom Harrison Talk 02:06, 7 December 2012 (UTC)


 * That's good, but it only addresses half of the issue.


 * In moving this article from compound engine, I think we have accepted that its former title was not sufficiently precise for the topic. The question now is, what is this ambiguity, and how do we help those looking for this alternative meaning to get to the information they want?


 * One obvious possibility is to add a redirect hatnote or similar. This seems to me logical. But it's not obvious why it would be acceptable to Andy Dingly when the original hatnote was, in his view, seriously unhelpful.


 * The other possibility that I can see is a two-way DAB at compound engine rather then leaving the current redirect. Or perhaps even three-way, as the existing hatnote pointing to compound locomotive suggests a third meaning. Perhaps this is more elegant, but it seems overkill to me, raises questions on primary meaning, and surely would be even less acceptable to Andy?


 * Curiouser and curiouser. Andrewa (talk) 15:44, 7 December 2012 (UTC)
 * Perfectly adequate as it is - CE redir to CSE, hatnote on CSE to CL, maybe redir of CSL to CL for completeness and ignore turbo-compound engine as too unrelated.
 * It could be argued that CE should be a DAB between CSE & CL. However within those circles that are already correctly distinguishing between engines and locomotives (which includes everyone reading in-depth articles on the topic, of which we have many) the general term in use omits "steam" as implicit and assumed. It would be unhelpful to make this either impossible (as there was now a DAB in the way), or to require every link to be piped.
 * The purpose of hatnotes is to recover the lost, not to define a taxonomy – and certainly not to create a taxonomy where none existed. We need a hatnote from compound engine to compound locomotive, because many readers will have arrived there looking for locomotives. However the likelihood of those looking for a highly obscure niche in aeroengine history ending up by mistake at compound steam engine is negligible. Andy Dingley (talk) 16:05, 7 December 2012 (UTC)
 * I don't see why a compound internal combustion engine should not be regarded as a compound engine. As well as the Turbo-compound engine there was also the Rolls-Royce Wankel Diesel . Biscuittin (talk) 16:51, 7 December 2012 (UTC)


 * Quite so. Fascinating link, but again this relates to the redirect, rather than to people arriving here directly. Hmmm, but I guess it raises the prospect of an overview stub rather than a DAB or redirect at compound engine. Might that be a better way forward? It's not obvious where else this engine should be covered, and it belongs somewhere.


 * but when we got to the police officer's station, there was a third possibility that we hadn't even counted upon... (-> Andrewa (talk) 17:30, 7 December 2012 (UTC)


 * I have made a start at User:Andrewa/Compound engine. Andrewa (talk) 17:47, 7 December 2012 (UTC)


 * Agree completely that The purpose of hatnotes is to recover the lost, not to define a taxonomy. Good point. Hear hear. Now please, can we apply this principle?


 * Agree also that the DAB is a bad idea. I think I said that before, and just raised it for completeness. So we have consensus on that too.


 * Disagree that the likelihood of those looking for a highly obscure niche in aeroengine history ending up by mistake at compound steam engine is negligible, but let's not argue about that as in any case it misses the point completely. The question is not about people arriving directly at compound steam engine, but only about those arriving at compound engine which currently redirects here.


 * There is no previous mention here of aeroengine history, it's another example of a turbo compound engine, yes, and dealt with in that article but is new to this discussion. It may even be yet another reason to add the hatnote if as I suspect you are wrong in this, but it's irrelevant to the reasons already given above for adding one, which do not relate to aero engines.


 * In fact you have still given no reasons at all for objecting to the hatnote, unless you count the sweeping phrase too unrelated. Would you care to expand on this, bearing in mind that, as agreed above, the test of a good hatnote is simply that it helps people to find what they are looking for, and questions of what the topic should be called are irrelevant to this. Andrewa (talk) 17:17, 7 December 2012 (UTC)


 * The whole discussion on hatnotes becomes (mercifully) irrelevant if we move the new stub article I've been working on at User:Andrewa/Compound engine into the article namespace. Thanks to Biscuittin for the excellent research that suggested this solution. Andrewa (talk) 19:44, 7 December 2012 (UTC)

Is this right?
I admit I mostly focus on locomotives, but I'd always read that the point of a compound is to extract more work from the low pressure steam that would otherwise simply escape to the atmosphere without the retained energy being tapped for use. This seems to suggest that the overall entrance and exhaust pressures and temperatures are the same for a simple engine and a compound, and all the savings come from spreading the same amount of expansion over several cylinders. Is this true? Because if it is, then what I've read in a number of books is all wrong. Or perhaps there is a difference between locomotive compounds and stationary ones? Like, perhaps the possible stroke of a steam locomotives cylinder is limited by the size of the wheels, and thus a simple locomotive is forced to exhaust steam at a far higher pressure than a stationary engine, simply because they can't fit a long enough cylinder to allow complete expansion? I'm not sure if that makes any sense though; couldn't they just fit a larger diameter cylinder to get the same expansion ratio? In any case, if what I've read in all these book is wrong, then I'm likely not the only one who is mis-informed, and perhaps the article should address this and explain why that's NOT the case.

I have this suspicion that BOTH are accurate; a simple engine cannot undertake to expand the steam enough to extract all, or even most, of the energy, since it would require a very long stroke and extreme heating/cooling cycles. Thus simple engines are forced to exhaust their steam while still at relatively high pressure. A compound engine allows the would-be "waste steam" to be expanded further in a separate cylinder, avoiding both the ultra-long stroke and the extreme cooling cycles, and perhaps allowing the stroke and cooling cycles of the high-pressure cylinder to be slightly shorter at the same time. Say the simple cylinder expands the steam to 60%, then exhausts it, wasting 40% but avoiding extreme cooling cycles; a compound would allow the HP cylinder to expand it to only 40%, and the LP cylinder would expand it another 40%, for a total of 80%, so you're extracting 20% that would have been wasted otherwise, but with smaller amounts of heating and cooling happening in each cylinder at the same time. That sounds reasonable to me; it would explain how a compound both extracts more energy, and in a more efficient manner, than a simple.

Yet this article seems to suggest that a simple cylinder DOES fully expand the steam, and the sole reason for its inefficiency is because this causes extreme cooling cycles. It doesn't mention anything that I see about a compound allowing for MORE expansion, just more efficient expansion. I suspect that is not accurate (or, rather, that it's not phrasing it quite right), and that a simple engine is inefficient because it CANNOT be made to efficiently fully expand the steam, BECAUSE of the described cooling cycles that would occur, not because the actually are features of a simple engine. I have a book somewhere in the piles around here that might mention this. I'm going to take a look for it. In any case, the secondary benefits listed all seem pretty right-on (lighter weight, less condensation, etc).

If I'm wrong, I'd really like to know, because I don't like being misinformed. And I've definitely read that a compound steam locomotive "is to extract work from still-heated steam that would otherwise be wasted to the atmosphere" (paraphrased, of course)..45Colt 06:24, 14 November 2015 (UTC)


 * ✅ Addressed in.
 * TuxLibNit (talk) 19:53, 1 July 2016 (UTC)

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Nonsense?
Surely this is this nonsense: I cannot imagine that anyone who served in a WW2 convoy on a newly built Liberty ship would agree that high vessel speed was not needed. Surely the issue was that reciprocating steam engines were easier and cheaper to build in the large volumes required. My point would seem to match what is said in the main article on the subject.ThoughtIdRetired (talk) 19:24, 27 November 2017 (UTC)
 * "Essential" is a strong term, and as ships were indeed built without, clearly it wasn't.
 * Yes, high speed was vitally important for the survival of that ship (although in fact had far less influence on survival than either convoy tactics or the current state of the anti-submarine war). However being able to build an engine was essential, resultant speed was not. So the Liberty ships, as the most expendable (compared to warships and troopships) were those that received the piston engines, from the piston engine builder who'd be otherwise underused, and who didn't receive the very few turbines being manufactured from their specialist makers. At the time, there was also considerable demand for turbines in order to build more electricity generating plants, to power more factories.
 * That said, the piston engines being supplied at this point were pretty sophisticated. Designs like the Skinner Unaflow were rather better than some old Victorian thing. Also the Liberty hull had the proportions of a cargo hull, and cheaply formed bow and stern plating, neither of which really aided high speed. Andy Dingley (talk) 20:28, 27 November 2017 (UTC)
 * Agree on all these points - though I think the views of merchant seamen of the era on a 6 knot convoy versus a faster one are relevant - I only have memories of discussions with those involved with this at the time, so I'm thinking someone with the right books might dig up a decent reference. In any case, the sentence needs a bit of a rewrite - but I will leave alone on the presumption that someone with better sources than me can do the job.ThoughtIdRetired (talk) 21:13, 27 November 2017 (UTC)
 * AIUI, the Liberty ship survival rates were higher than many, simply because they were used later in the war after the "happy times" of the early U boat campaign. They were also faster than many of the other, older merchantmen around (which were thinned out by submarines).
 * There is though a deliberate speed difference between the first Liberty and Ocean ships and the later Victory designs (11 vs 15 knots) when better engines (including steam turbines) became available again and allowed the power to be pretty much doubled. They also had better shaping to the bows, a combination of more space in the plating shops to do the work, also welding rather than riveting. Andy Dingley (talk) 21:57, 27 November 2017 (UTC)