Talk:Aerojet LR87

Number of nozzles
See Talk:LGM-25C Titan II. Andrewa (talk) 05:29, 13 July 2013 (UTC)

That discussion has been dormant for some time. Meanwhile, our articles on the LR-87 and the rocket missiles that it propelled remain woefully inconsistent. And really authoritative sources seem surprisingly hard to find.

There are I think two possibilities:
 * Take the risk of WP:OR and treat all versions of the LR-87 as one engine with two nozzles.
 * Be pedantically WP:NPOV and take no stand either way.

Either way requires a considerable amount of work to implement, so I'd like to have a strong consensus on which to pursue.

It seems clear to me that neither a single-nozzle nor single-chamber version of the LR-87 has ever been built. In all versions, several vital components are shared between the two chambers and nozzles in such a way that the two can only be fired as a single unit. To scale these systems down to support only one nozzle has never been attempted.

However, one now-inactive editor claimed that ''the LR-87-5 was a single chamber engine, which was fitted as a pair on the Titan II first stage. That is in contrast to the LR-87-3 of the Titan I, which was a two chamber engine with shared turbo-pump...''. This seems quite widely believed, but despite considerable effort we have no good sources to support it.


 * Perhaps I was hasty in describing them as inactive, they have returned below! Welcome, and no offence intended. Andrewa (talk) 18:59, 15 March 2014 (UTC)

An IP with no other contributions has said ''It never occurred to me to consider it a single engine. We always referred to them as "engines". To be precise (and having worked on them in the USAF, I know)...two thrust chambers and four turbo pumps (two per thrust chamber). That of course suggests that they are two engines, but they did share peripheral support systems. The hot gas generator (for pressurizing the propellant tanks) the lubrication system and the drive unit (a small reaction chamber where a negligible amount of propellant was reacted to drive the turbopumps for the thrust chambers) were critical parts of the engines. In that respect it is proper to say that since the thrust chambers could not operate independently, they must, therefore be considered a single unit.'' (my emphasis)

That to me explains a lot. The in-house jargon was always engines, but the more considered opinion is that it's a single engine. All versions. And of course we will always have well-meaning editors who take one look at the photo at left and say to themselves it clearly has two engines and "correct" the text to match. (I have the same trouble with the photo of my fretless ABG. ) From that point of view, it would be really good to have a clear conclusion to our discussion here.

See also RD-180 which is always considered a single two-nozzle engine AFAIK.

Comments? I have posted heads-ups at WikiProject Rocketry (which seems inactive) and WikiProject Aviation. Andrewa (talk) 02:04, 15 March 2014 (UTC)

And now also at WikiProject Military history and WikiProject United States following the addition of those to the talk page header by a very active  IP. Andrewa (talk) 11:01, 15 March 2014 (UTC)


 * Gunston, W; "Rockets and missiles", Leisure Books (1979), Pages 64-5, describes the LR87-1 of the Titan I as having "twin gimballed chambers" and "The LR87-5 engine" of the Titan II as also having "twin chambers." Another similarly-conceived but far smaller engine I came across recently is the  Armstrong Siddeley Beta. Van Pelt, M.; "Rocketing Into the Future: The History and Technology of Rocket Planes", Springer (2012) Page 149, describes it as a "rocket engine" (singular) and says that it "had two combustion chambers and nozzles ... and these could be independently swiveled." HTH. &mdash; Cheers, Steelpillow (Talk) 12:33, 15 March 2014 (UTC) (Just to make clear since these refs are somewhat one-sided, I am not cherry-picking, I have no axe to grind, just a couple of books to hand). &mdash; Cheers, Steelpillow (Talk) 12:36, 15 March 2014 (UTC)


 * Great stuff!


 * It seems to me that these sources support the view that all versions of the LR-87 should be regarded as being a single two-nozzle engine... the first option of my two bulleted ones above.


 * I have no axe to grind either, except of course wanting to improve Wikipedia, see WP:creed. But it seems to me that we need to be consistent on this. Andrewa (talk) 19:18, 15 March 2014 (UTC)


 * Hi Andrew, there is a big difference between the RD-180 and the LR87-5: The RD-180 has only one turbopump assembly feeding the two thrust chambers. The LR87-5 has it's own pump assembly for each chamber, as the IP wrote on the Titan II page. So as I understand it and also as the IP described it, those are technically two engines. But they share various support systems, and therefore can't be run independently. So from what I understand, ONE LR87-5 consists of TWO engines (pumps, chambers, nozzles) mounted together sharing certain parts, but unlike the RD-180 the two chambers are not fed by a single pump assembly. So a Titan II first stage has only ONE LR87-5, but with TWO sub-engines.Geomartin (talk) 13:50, 15 March 2014 (UTC)


 * The important claim here is that ONE LR87-5 consists of TWO engines (pumps, chambers, nozzles) mounted together sharing certain parts. Have you any sources to back this up?


 * If this claim can be supported then there are two more options to my bullet points above, see below. But we need sources.


 * I did a quick google web search on "LR-87" "sub-engine" rocket and got no hits. Is sub-engine your own term for this, or is it used by citeable authorities? Where?


 * Removing the LR-87 search term got a few hits but none of them seem relevant. Google books a similar blank.


 * However I did (with some tweaking I won't describe as I can't remember how I did it) get to http://heroicrelics.org/info/titan-i/titan-i-stage-1-engines.html which is a fascinating document. It does once say after checking that both engines are ready to fire, and taking that out of context it's not clear whether that refers to the stage one engines or the engines of both stages. But elsewhere it consistently refers to the stage one engine consisting of two subassemblies.


 * And that's for the Titan I, which our article already describes as having one first stage engine. So it doesn't tell us anything about the LR87-5 of the Titan II, leading to option 3 below, which seems to be the one you support (am I wrong?).


 * Our Titan II article also currently describes the first stage as having one engine but doesn't say which version. Andrewa (talk) 18:47, 15 March 2014 (UTC)

We now have four options to consider, as I see it:


 * 1) Treat all versions of the LR-87 as one engine with two nozzles.
 * 2) Treat all versions of the LR-87 as a two-engine assembly, each engine having one nozzle.
 * 3) Treat some versions as one engine, others (notably the LR87-5) as a two-engine assembly.
 * 4) Take no stand either way.

The sources we have so far all support option 1. Andrewa (talk) 18:47, 15 March 2014 (UTC)


 * Hi Andrew, sorry, the sub-engine term was my creation to point out what I mean. But I disagree here, I think the source we have point towards option two, in the way that the IP described it on the TII page. Have a look into Stumpf's book on the Titan II on google books, on page 38 you'll find a detailed drawing of the stage I engine. It clearly has a fuel and oxidiser suction line for each thrust chamber including two turbo-pump assemblies. You'll find that also on . When you'll look on |this website (I linked it before), you'll find the exact same thing for the TII-23G: The Titan first stage was powered by an Aerojet LR87-AJ-7 engine, consisting of two independently operated sets of turbopump/thrust chambers mounted on a common frame. Astronautix.com tells the same for the TII-23G. And finally from the manufacturer Aerojet for the Titan I engine: The two-stage system originally ran on Liquid oxygen (LOX) and RP-1. Stage 1 consisted of two pump-fed, gas generator cycle, regeneratively cooled engines on a single frame. So I think we have a strong case here for your option 2.Geomartin (talk) 09:49, 16 March 2014 (UTC)
 * @Geomartin, How do you make out that the quote, "The Titan first stage was powered by an Aerojet LR87-AJ-7 engine," supports the view that it has two engines? Do bear in mind that to interpret a source instead of taking it at face value is forbidden as original research, per WP:OR, and that WP:VERIFY sets "verification not truth" as our watchword. The manufacturer's words, "Stage 1 consisted of two pump-fed, gas generator cycle, regeneratively cooled engines on a single frame" are your best - and so far only - reliable support here (BTW, I took the liberty of fixing your link). Since it contradicts other reliable sources, I wonder whether Option 4 - take no stand either way - might be the only viable one. &mdash; Cheers, Steelpillow (Talk) 10:48, 16 March 2014 (UTC)
 * Option 4 doesn't help if we have conflicting sources. That source seems to apply to all versions. Andrewa (talk) 11:30, 16 March 2014 (UTC)
 * Seems to me that if we have conflicting sources, the only way ahead is to acknowledge - and reference - both PoVs. Otherwise one gets into pointless edit wars. Isn't that Option 4? &mdash; Cheers, Steelpillow (Talk) 15:07, 16 March 2014 (UTC)
 * Ooops, yes, quite right. Sorry, I was confused.
 * If we have two reliable sources, one using engine and the other using engines to describe a two-nozzle assembly, then we need to do something like option 4, in fact it's very important that we do. It's borderline OR, what we really need is an RS that explicitly says that authorities differ in this, because on this question of terminology the sources we are quoting are primary sources, not secondary.
 * See below for more on this. It's a subtle but important point. Andrewa (talk) 18:08, 16 March 2014 (UTC)
 * The other problem is, do we really have conflicting sources? Or do we just have one source which is itself inconsistent? Are there any that consistently refer to the two-nozzle assembly as two engines? If not that's an even trickier situation.
 * But this is more progress in any case. We are beginning to document what is really going on. Andrewa (talk) 17:05, 16 March 2014 (UTC)
 * At the moment I prefer to keep an open mind. If it becomes clear that all the reliable sources we can find point one way, there will be no problem. But I think it is too early to make that call, we need to give other editors a few more days to weigh in. BTW the sources I noted above, Gunston and van Pelt, are both secondary. And here's another secondary source: Taylor, M.; "Warbirds Illustrated No.12: Missiles", Arms and Armour (1983) Page 15, comments on "Titan I's first-stage rocket motor" (singular). No similar comment on Titan II unfortunately, just a general one referring to both stages together. &mdash; Cheers, Steelpillow (Talk) 18:05, 16 March 2014 (UTC)
 * This gets quite tricky, see below. These are both examples of usage. As such, they are in a sense primary sources, on this particular issue.
 * Agree we should take our time. This is a long-running and surprisingly complex issue, and I'm hoping others will come aboard and build a good and lasting consensus. Andrewa (talk) 18:20, 16 March 2014 (UTC)


 * The IP on the TII page concluded since the thrust chambers could not operate independently, they must, therefore be considered a single unit. That seems to support option 1, not 2.
 * The existence of two separate turbopump assemblies (each of two turbopumps) is not in question, the question is, does this determine that they are separate "engines", considering that other vital components of the engine/engines are shared?
 * https://www.rocket.com/titan-liquid-rocket-engine is an interesting page, and does as you say describe the assembly as consisting of two engines, and this seems to apply to all versions of the engine(s). Whether this one reference is a strong case is doubtful, but it is a good relevant source, and very much progress. Andrewa (talk) 11:30, 16 March 2014 (UTC)
 * Hi Andrew, I'm doing no interpretation, just repeating exactly what 4 sources tell (you ignored the second part of the quote on the LR87-AJ-7 saying two independently operated sets of etc.) I don't see any contradictions between the 4 sources I provided, they all tell the same story without interpretation: two engines, which share some parts on a single frame, make up the LR87-AJ-x.Geomartin (talk) 14:29, 16 March 2014 (UTC)
 * No they do not. I asked you above how you can see the quote, "The Titan first stage was powered by an Aerojet LR87-AJ-7 engine," (singular) as supporting the view that it has two engines (plural) - because, of course, it does not. And that's all this is, a discussion about the form of words to use in the article, nothing more. &mdash; Cheers, Steelpillow (Talk) 15:17, 16 March 2014 (UTC)
 * Quite right. And once we have the terminology sorted out, we can then use it consistently in the infoboxes etc. of the various articles on the missiles that use this engine assembly. That is what started all of this. Andrewa (talk) 17:18, 16 March 2014 (UTC)
 * I didn't ignore that part of the quote. I don't think it's relevant. The two nozzles have some degree of independence, yes, but they cannot be fired except as a pair. This is not independent.
 * And there is only one source yet as far as I can see, not four. One of the links you provided is broken and gives a 404 page not found error. Two of them are the same source, just in printed and online form. One of the remaining two is a diagram and doesn't say whether the authors regard this as one engine or two.
 * So we are left with https://www.rocket.com/titan-liquid-rocket-engine as the only example (see below for why I bold that) yet of usage of the plural engines to describe the two-nozzle assembly. And it's an excellent source, but so far is on its own, as far as I can see. Andrewa (talk) 06:10, 17 March 2014 (UTC)

I have just posted extra heads-ups at all affected articles that I can find (see below) and also at Wikipedia talk:WikiProject Spaceflight. Andrewa (talk) 23:47, 17 March 2014 (UTC)

Verification and truth
I think it's worth having a separate conversation on the question of exactly what we must reject as WP:OR. This is probably the clearest case I have yet seen of a basic problem we sometimes encounter in applying this policy.

Just suppose that we can't find a reliable source that explicitly says either the LR87(-x) is a single two-nozzle engine, or the LR87(-x} is a single nozzle engine always used in pairs, or words to that effect either way. That's a thought experiment, we haven't found such sources either way so far and may or may not. Or there's a third possibility, we might find a source that explicitly says authorities differ as to whether a two-nozzle LR87(-x) is a single engine or an assembly of two engines. That would be even better, but again we may or may not find such a source, and haven't yet.

In any of these three cases, we would have a reliable secondary source to cite. But we don't have any such yet. So let's just suppose for the purpose of this section that we have no such RSS.

Let's further suppose that we have reliable sources that do use both the term engine and the term engines in referring to a single two-nozzle LR87(-x) assembly. That also appears to be the case so far, and for the purposes of this section let's assume it is the case.


 * At the risk of labouring the point, what I'm trying to distinguish is between sources which are examples of usage, which we have, and sources which offer interpretation of this data, which we don't yet have and which WP:OR urges us not to do for ourselves. Andrewa (talk) 18:29, 16 March 2014 (UTC)


 * This kind of inconsistent usage crops up a lot in the real world. Language is a flexible thing and exhaustive definitions of words usually only get cooked up for a specific expert discussion. As long as the meaning is clear, people are generally content. It only becomes a problem on Wikipedia when some editor decides to make a meal of one particular PoV. I would be very surprised if anybody else on the planet has taken the issue seriously enough to comment on it in a reliable source. That is to say, I doubt that anybody has ever explicitly offered an interpretation as such and, as WP:OR points out, we would be wise not do so either. &mdash; Cheers, Steelpillow (Talk) 19:57, 16 March 2014 (UTC)


 * Well put. But this sort of POV-pushing is not uncommon in Wikipedia in my experience... the rather touchy attitude of WikiProject Chemisty members to any suggestion that IUPAC recommendations should be acknowledged when they differ from the current practice of University textbooks (which happens quite a lot, to my surprise) for example. This attitude has come about following repeated attempts by others (normally with little chemistry) to naively apply the IUPAC recommendations, which is just the opposite POV. I'm taking a break from that one but intend to chase up dead-tree sources one day and have another go... (->


 * But back on-topic, I'm interested to see how this translates to the infoboxes of specific missile articles. Andrewa (talk) 03:24, 17 March 2014 (UTC)

What do we do?

We do need to do something. I mean, we could I suppose just delete and protect all the relevant articles, problem solved, but obviously that's overkill. Or we can, in the infoboxes etc, avoid saying number of engines at all, and instead we use some safe if awkward terminology like number of main engine nozzles.

But that on its own doesn't make for a good encyclopedia. It's far more helpful to the reader if we also say why we are avoiding the simple term engine. And this is also necessary to prevent endless edit activity which may not quite be an edit war but is equally pointless and time consuming, as editor after editor finds a reliable source which simply uses engine or engines, and then proceeds in good faith to "correct" the article(s). (Which is the situation we now have.)

So in this case I would argue, we need to in some way report on the primary sources we have, to point out in a footnote perhaps that sources are not consistent in their terminology.

Whether we elect to arbitrarily follow one usage or the other, or whether we instead just avoid either and accept some rather awkward and legalistic phrasing as a result, I don't much care. The point is, either way I think we need a footnote or similar to say why we are doing what we are doing, both to make for the best reader experience (our bottom line) and to reduce the overhead of endlessly reinventing the wheel.

I can't see any way of avoiding this footnote, or any way that it doesn't represent original research. In the scenario described above, it's based entirely on primary sources, because the assumption is that, strictly speaking, there are no secondary ones regarding this particular issue.

Comments? Andrewa (talk) 18:02, 16 March 2014 (UTC)


 * I have bumped into this issue a few times. One thing to remember is that words are there to communicate a fact. The form of words does not matter as long as it makes the fact clear. I'd write something like, "The LR-87 is a rocket engine comprising two combustion chambers and exhaust nozzles in a single assembly.[refs] It is sometimes describes as a power plant comprising two engines with common ancillary equipment.[ref]" Then, in the text, avoid the use of "engine" where sensible, so as to reduce the risk of edit warriors, sticking to "assembly" or "installation" on the one hand and "thruster" or similar on the other. Where "engine" is the only sensible alternative, take care that the context makes clear what is meant. There may be no peace at the end of the rainbow, to mix metaphors, but I have found that once in place a clear, rational and properly-sourced treatment is hard to argue with. &mdash; Cheers, Steelpillow (Talk) 18:23, 16 March 2014 (UTC)


 * Agree. But how would you handle the infoboxes? That's the specific problem that set all of this off. Priorities as I see them: (1) Reader experience. Article should be clear and accurate. (2) Editor experience. Newbies in particular should not be needlessly tempted to make unproductive changes (which of course also impact reader experience until reverted) both from the point of wasting their time and of frustrating them when their work is challenged and/or simply reverted. Andrewa (talk) 18:48, 16 March 2014 (UTC)


 * The infoboxes are structured around the assumption that it is a single installation. Wherever possible, values should be for the combined system. This is the approach taken for example in Pretty, R.; "Jane's Pocket Book 10: Missiles", Macdonald and Jane's (1975), which incidentally does not even mention the dual chambers. Is there anything in the infoboxes which unambiguously requires a value for a single chamber? &mdash; Cheers, Steelpillow (Talk) 19:57, 16 March 2014 (UTC)
 * Oops, you mean those infoboxes, grin. Well, in Number of engines, I think "1 dual-chamber LR-87" is easy enough, and the thrust should be the total for the LR-87. Anything else would be mental. &mdash; Cheers, Steelpillow (Talk) 20:01, 16 March 2014 (UTC)
 * As above, interested to see it in practice. At the risk of jumping to a solution, we may be close to one here. Andrewa (talk) 03:24, 17 March 2014 (UTC)

Affected articles
I think it's now timely to survey exactly which articles are affected by the question of whether the two-nozzle LR-87 assembly is one engine or two, per above. Bolding is my emphasis.


 * The lede of the LR-87 article currently reads Though this powerful engine used two discrete combustion chambers, it is considered a single unit.
 * The Titan (rocket family) article currently reads in part (my emphasis added):
 * It was a two-stage rocket whose LR-87 engine was powered by...
 * The Titan II used LR-87-5 engines, a modified version of the LR-87...
 * The same first stage rocket engines were used with some modifications.
 * Titan II GLV infobox reads ''First Stage Engines	1 LR-87
 * Lede reads in part The first stage was powered by an LR87 engine (although this engine has two combustion chambers and nozzles, it is considered a single unit because both chambers use common turbomachinery)
 * HGM-25A Titan I infobox reads Engines	1LR-87
 * First Stage:... Number of engines: Two – Aerojet LR-87-3 ]
 * LGM-25C Titan II infobox Engines	1 LR-87
 * Stage I and Stage II vehicles each contain propellant and pressurization, rocket engine...
 * ...when the Titan's right engine experienced severe combustion instability at ignition that caused the entire thrust chamber to break off of the booster and fall down the flame deflector pit, landing about 20 feet from the pad (the Titan's onboard computer shut the engines down the moment loss of thrust occurred). The problem was traced to a bit of cleaning alcohol carelessly left in the engine. A new set of engines had to be ordered from Aerojet...
 * The first stage consists of one ground ignited Aerojet LR-87 liquid propellant rocket engine (with two combustion chambers and nozzles but a single turbopump system)...
 * Titan IIIA infobox First Stage Engines	2 LR87-11
 * Titan IIIB infobox First stage (Titan 23B/33B) Engines	2 x LR87-AJ-5
 * Titan IIIC infobox First stage Engines	2 x LR87-11
 * Stage 1 uses two LR87 liquid propellant engines.
 * Titan IIID infobox First Stage Engines	2 LR87-11
 * Titan IIIE First Stage Engines	2 LR87-11
 * Titan 34D no relevant text, infobox does not mention engines but perhaps should
 * Commercial Titan III no relevant text, infobox does not mention engines but perhaps should
 * Titan IV infobox just reads First Stage Engines	LR87
 * Stage 1 used an LR87 liquid-propellant rocket engine.

Are there any I've missed?

Now the above seems mostly but not entirely consistent with the theory that the Titan I LR-87-3 first stage engine was a single two-nozzle engine, but the Titan II LR-87-5 first stage engines had sufficient independence between the chambers for the assembly to be considered two single nozzle engines. This has been suggested in previous talk page discussions, here is just one example, so it needs to be aired I think. But no evidence (apart from the opinion of contributors, based on their interpretation of the specifications) has been produced that this is the case, despite a great deal of discussion. I'm very interested in any that can be found.

And there are still some other obvious but relatively minor problems. The HGM-25A Titan I and LGM-25C Titan II articles for example are each internally inconsistent, despite each describing a single model of LR-87. Note also that one of these missiles used the LR-87-3 and the other the LR-87-5. We are at least consistently and comprehensively inconsistent! (->

My current theory is that our current content is just confused and confusing, and that it needs to be fixed. But I don't recommend fixing any of it right now. Let's first try for a consensus on what if anything needs fixing, and how to fix it. Andrewa (talk) 07:35, 18 March 2014 (UTC)


 * I took the liberty of adding Commercial Titan III to your list.
 * Thank you! Good catch. And thanks for following my pattern of using a permalink... it's a bit more trouble but it will make this discussion far easier to follow when it's (hopefully) archived one day. Andrewa (talk) 11:54, 18 March 2014 (UTC)
 * I also just googled Aerojet LR 87 and the first page of hits mostly describe all versions as an "engine" (singular), though there are a few exceptions such as the Aerojet site mentioned earlier. The National Museum of the US Air Force appears to settle the matter for us by being explicit about the issue. Its page on the Aerojet-General LR87 Liquid Rocket explains (my bold) that, "Though this powerful engine is in reality two engines working together, it is considered a single unit." From all that has gone before, I think the Museum's view is now unassailable, as per WP:COMMONNAME, and that applies to all variants. Infoboxes must treat it as a single unit, i.e. a single two-chamber engine. Some latitude may be appropriate in the article text, for example we should allow phrasing such as, "Though this engine is technically two engines working together, it is considered a single unit," or, if someone writes "in this variant, each engine had its own turbopumps," provided the meaning is not being tampered with by a PoV monkey, we should not go all "pedant-police-patrol" and rewrite it for the sake of it. &mdash; Cheers, Steelpillow (Talk) 10:49, 18 March 2014 (UTC)


 * Agree. You seem to have hit on a much better search string than I managed. Great link. And agree re pedantry. The bottom line is simply, will the general reader come away informed, and not misinformed?


 * But part of this is to try to harden the articles against well-meaning edits that are just plain wrong. Which is not always easy. The drum kit article is one of the most heavily vandalised that we have, and about half of it seems to be in good faith. So maybe the drummer jokes (like all good jokes) have a basis in fact. (But I'm still proud to be a drummi... drammie... uh... drimbal... oh damn... I play the drums.)


 * The other thing we need to do eventually is to check the figures in the infoboxes (particularly) and in-text specifications for consistency... when I last checked (before I gave up and took a WikiBreak from the issue) there was at least one article that quoted the engine thrust and weight etc for a single chamber ie assumed two first stage engines, but listed the number of first stage engines as being 1 ie assumed an engine had two chambers... or else the other way around. Such a mistake is glaringly obvious when pointed out as the figures are of course wrong by a factor of two, but that's not great enough to be obvious if you're not looking for it. Or it wasn't for me, anyway. Andrewa (talk) 11:54, 18 March 2014 (UTC)


 * I have generally found that once an issue has been described without bias and reliably referenced, the agitation dies down quite quickly. Residual openings for the PoV monkey will be exposed and blocked for a while until there are none left. The odd aggressive PoV editor may even have to be blocked by an Admin but that seems less common these days - natural selection, I suppose. Anyway, in the present case I would hope that citing the National Museum quote at every reasonable opportunity should set that process moving nicely. Links to this discussion in the edit comments might be a good idea too. But of course, there will always be the odd flurry to be worked out on the talk pages - this is Wikipedia after all. &mdash; Cheers, Steelpillow (Talk) 12:24, 18 March 2014 (UTC)


 * BTW I can't sing in tune so I wanted to play the drums until I discovered that even they need tuning too. And keyboards needed two hands playing independently, also beyond me. By the time high-quality programmable synths came along I was too old to learn to be a musician. But I am brilliant at playing the 12-inch disc, so all is not lost &mdash; Cheers, Steelpillow (Talk) 12:29, 18 March 2014 (UTC)
 * These days the theory is that nearly everyone can learn to sing in tune... the main reason that people don't learn pitch is that they've been told they can't. The drums of a drum kit are mainly used as unpitched percussion, "tuning" them is probably not the best term... but we're stuck with it. Like many drummers I tune my drum heads to the drum shells rather than to specific notes... although that is done by some drummers too.
 * Hahaha. Experts with a chip on their shoulders, they hate facts. At the age of 16 I realised I had spent over half my life trying to tune my hated violin or even to play a scale reliably in tune. I would hear a slight error, nudge the note away from the discord, and find I was now a tone out! Hopeless, never could hear sharp from flat, just knew it was awful. Confronted with the truth, teacher and parents finally but reluctantly agreed to give up. Classical timpani (used in the school orchestra) do have to be tuned to the note, wish I'd learned more about rock drumkits now.... &mdash; Cheers, Steelpillow (Talk) 11:56, 19 March 2014 (UTC)


 * You sound like a classic case. Not everyone should learn the violin, to say the least. A prestigious private school I attended (and hated... their "school orchestra" when I was there was seven players including a teacher and so pathetic that I was careful that they never found out I played the flute lest I be pressured into joining), some time after I left, employed a music teacher of international stature. Part of his package was that every student would learn the violin. Over time the school thus built a full orchestra that was the envy of every school in the state, based on those who did have above average ability, at the cost of damaging those who didn't for life. It was abusive. Yes, there are many tuned drums, timpani are one case, the tabla is another. One day I'm going to get a set of snare drums together and do a youtube of baa baa black sheep or something similar on them to demonstrate something important about the difference between unpitched percussion and pitched percussion. I've also played a set of tuned cymbals by Paiste, they are called cup chimes but they are physically just tuned splash cymbals. Andrewa (talk) 06:17, 20 March 2014 (UTC)


 * Two excellent drummers who have tuned their toms to definite pitches are Terry Bozzio as of 2012 and Phil Treloar at least in his early days. In the 1960s Phil played a 4-piece minikit tuned in 4ths from the bass drum at G, floor tom C, hanging tom F and snare Bb, and I had a personal demo and passionate explanation of why it was the best ever tuning from him then, but didn't ever adopt it myself. On the other extreme Terry's 2012 kit has to be seen to be believed, see http://terrybozzio.com/kit-setup/ for details (or there's a photo of a smaller (!!!) version at drum kit), and youtube for a demo, and yes he really can reach it all. Andrewa (talk) 15:45, 23 March 2014 (UTC)
 * Wow! But don't tell me, tell someone who can do something about it. I remember losing count of the synths Rick Wakeman was playing in Yes. That's another problem I have, I can't coordinate independent movements of left and right hand, so that stuffed my piano playing. I could go on. &mdash; Cheers, Steelpillow (Talk) 16:44, 23 March 2014 (UTC)


 * Back on topic, I've posted a few more heads-ups, see above. Probably good to wait a few says to see the reaction.
 * If no more comments, I'm going to claim a (very) rough consensus that we should follow the National Museum usage. Andrewa (talk) 13:41, 18 March 2014 (UTC)

Caution
It appears obvious that some articles are going to be changed as a result of this discussion.

But, suppose we do decide that (with suitable explanations and references) we're going (as I hope) to always regard the LR-87 as a single engine with two nozzles, all versions. Does that mean we simply change every infobox that says Engines: 2 x LR87 or similar to say Engines: 1 LR87 two-nozzle assembly or similar?

No way. We need to check what else the infobox and article says, and whether thrust and engine weight are quoted for the whole stage or per engine or per nozzle, for example, and whether they even matched up as we found the article. Failure to do this will introduce errors of fact (and almost certainly has in the past but I have no diff to quote right now). Andrewa (talk) 03:17, 19 March 2014 (UTC)
 * Agreed. We need to take each article as a whole. (Though there is no law that says we have to do it in a single edit, or even in a single day). &mdash; Cheers, Steelpillow (Talk) 11:40, 19 March 2014 (UTC)


 * (And just as well.) Andrewa (talk) 06:27, 20 March 2014 (UTC)

Consensus?
It seems to me that we have strong consensus above that the various articles listed are currently inconsistent, and that this should be fixed,

It further seems to me that we have a rough but policy and evidence based consensus above that the best way to do this is to treat all variants of the LR-87 as a single engine with two nozzles. Most but not all sources, and the best sources, are consistent on this.

But I'll wait a little longer before starting to bring the articles into consistency based on this understanding. Andrewa (talk) 01:01, 24 March 2014 (UTC)


 * Looks like a plan. Agreed. &mdash; Cheers, Steelpillow (Talk) 09:57, 24 March 2014 (UTC)


 * As a first step I have posted heads-ups as to this proposal at the talk pages of the twelve other articles listed above as affected. Andrewa (talk) 08:25, 26 March 2014 (UTC)


 * As a second step, this article itself has had a few tweaks. Andrewa (talk) 09:01, 27 March 2014 (UTC)

The USAF considered the LR87 as 1 engine with 2 thrust chambers. "T.O. 21M-HGM25A-1-1 Technical Manual Operation and Organizational Maintenance HGM-25A Missile Weapon System" makes that very clear. Figure 1-60 "Stage I Rocket Engine Subassembly", on page 1-102, lists item 15 as Thrust Chamber 1, and item 17 as Thrust Chamber 2. Paragraph 1-243 (page 1-101) states "STAGE I ROCKET ENGINE. The Stage I rocket engine, designated LR87-AJ-3, consists of two engine subassemblies. (See figure 1-60.) The two subassemblies develop a total of 300,000 pounds of thrust and are mounted on a common engine frame . . . The subassemblies are similar and are interconnected by instrumentation and electrical components."

Sutton in "History of Liquid Propellent Rocket Engines" states "The booster engine has twin LPREs with regeneratively cooled gimbal-mounted thrust each with it's own turbopump."

Mark Lincoln (talk) 01:59, 16 February 2016 (UTC)

Articles updated
I've moved this list to User:andrewa/LR-87 article updates to remove the need to sign changes. Feel free to update it there. Andrewa (talk) 06:47, 5 April 2014 (UTC)

Engine versions
I've started a page as a temporary repository for statistics such as engine weight and thrust, to help with the checking of whether any are understated by a factor of two because they are quoted for a conbustion chamber and nozzle. See User:andrewa/LR-87 versions, and feel free to update it there. Andrewa (talk) 06:47, 5 April 2014 (UTC)

I have some LR87 numbers for you from a reputable source.

Titan I LR87-AJ-3

Thrust = 382,000 (lbs vacuum)

Thrust = 300.000 (lbs sea level

Specific Impulse = 258.8 (S sea level)

Specific Impulse = 315/329 (Is S vacuum)

Propellants = LOX/Kerosene (RP-1?)

Mixture Ratio = 202

Chamber Pressure = NA (psia)

Nozzle Area Ratio = 8

Titan II LR87-AJ-5

Thrust = 473,800 (lbs vacuum)

Thrust = 430.000 (lbs sea level

Specific Impulse = 278 (S sea level)

Specific Impulse = 285.2//309 (Is S vacuum)

Propellants = NTO/Aerozine 50

Mixture Ratio = 1.930

Chamber Pressure = 795 (psia)

Nozzle Area Ratio = 8

Titan II LR87-AJ-5

Thrust = 473,800 (lbs vacuum)

Thrust = 460.000 (lbs sea level

Specific Impulse = 258.8 (S sea level)

Specific Impulse = 285.2/309 (Is S vacuum)

Propellants = NTO/Aerozine 50

Mixture Ratio = 1.930

Chamber Pressure = 795 (psia)

Nozzle Area Ratio = 8

Titan III LR87-AJ-11

Thrust = 527,800 (lbs vacuum)

Thrust = 430.000 (lbs sea level

Specific Impulse = 258 (S sea level)

Specific Impulse = 296/318 (Is S vacuum)

Propellants = NTO/Aerozine 50

Mixture Ratio = 1.75

Chamber Pressure = 823 (psia)

Nozzle Area Ratio = 12

Titan IV LR87-AJ-11A

Thrust = 550,900 (lbs vacuum)

Thrust = 489.000 (lbs sea level

Specific Impulse = NA (S sea level)

Specific Impulse = 303.5/316.2 (Is S vacuum)

Propellants = NTO/Aerozine 50

Mixture Ratio = 1.91

Chamber Pressure = 854 (psia)

Nozzle Area Ratio = 16

Mark Lincoln (talk) 19:35, 16 February 2016 (UTC)
 * , Looking at this source, is there an explanation for the second number in parentheses for vacuum specific impulse? It seems consistent with the vacuum-optimized specific impulse of the LR91 upper stage engine. In the source table (Sutton: History of Liquid Propellant Engines, table 7.7-1 "Several Key Parameters of Titan LPREs", page 382) the entries for upper stage (LR91) specific impulse are suspiciously missing, leading me to believe they were misplaced.
 * In related news, do you know of a print source that covers engine parameters by model? Sutton refers to the engines by Titan generation (I/II/III/IV) rather than by model number (e.g. AJ23-139 or LR87-7) and the numbers don't really match with the model-by-model parameters given by astronautix.com. – Anon423 (talk) 14:30, 27 August 2021 (UTC)
 * In related news, do you know of a print source that covers engine parameters by model? Sutton refers to the engines by Titan generation (I/II/III/IV) rather than by model number (e.g. AJ23-139 or LR87-7) and the numbers don't really match with the model-by-model parameters given by astronautix.com. – Anon423 (talk) 14:30, 27 August 2021 (UTC)

Astronautics is a useful initial source. Sutton is a far better source. Beyond that you have to consult a variety of sources. The performance of the LR91 is specified for a vacuum. The details I have provided are the most accurate I could determine. The LR87 was an astounding engine which has burned a wider variety of propellants than any other engine I am aware of. Note that in the Titan I LR87-AJ-3 it burned lox/RP-1, in the LR87-AJ-5, and later LR87-7, LR87-AJ-11 and 11A it burned Nitrogen Tetroxide-Aerozine 50. The LR91-2 ran on LOX/RP1 while the LR91-3 ran on Nitrogen tetroxide and Aerozine 50 as did the LR91-7, 9 & 11. The LR87 was also fueled with Alumazine, which was 56.7% Aerozine 50, .3% Carbopol 904 gelling agent, mixed with aluminum powder to attain a higher specific impulse for the proposed Titan IIA. The gelled aluminum fuel suffered instabilities and cooling problems and was not pursued. The LR87 was also successfully operated with Liquid Oxygen oxidizer with Liquid Hydrogen as the fuel which required modification to the injectors and fuel pump. The LOX/LH2 engine was run some 50 times. I know of no other rocket motor which was operated with four different fuels and two oxidizers. An amazing rocket engine.

Mark Lincoln (talk) 22:02, 22 January 2022 (UTC)

LR-87 LH2
Did this version ever fly? It seems to have been ground tested only. Much is made of the fact that the LR-87 in its various versions used three different fuel combinations, but it seems to me that only two of them ever flew.

And it's just possible that the LH2 version was a single chamber engine... see


 * http://www.friends-partners.org/partners/mwade/graphics/l/lr87lh2.jpg an image of a single chamber engine, possibly an LR-87 LH2.


 * http://www.astronautix.com/engines/lr87lh2.htm an article that uses the above image.

Interesting... It might explain a lot. Andrewa (talk) 00:58, 5 April 2014 (UTC)

"One Titan I booster engine with a new fuel pump was later ajso ground tested with LOX/H2."

Mark Lincoln (talk) 18:03, 16 February 2016 (UTC)

This Article Has the Wrong Name
There is no LR-87 and never was. The proper nomenclature is LR87. The designation system in use for jet and rocket engines excludes placing a hyphen between the letters describing the engine and the numbers indicating the serial acceptance of the engine.

Below is an document explaining the nomenclature in use since 1945:

"1. Representatives of the Navy Bureau of Aeronautics and of the Air Technical Services Command have agreed on the following general system of designating aircraft jet propulsion engines:

a. The system will be composed of two parts separated by a dash. The first part will consist of a letter(s) describing the general nature of the engine and a number designating the serial acceptance of the type. The second part shall consist of a number designating model under the basic type. The letters to be used in the first part of the designation are as follows with definitions as shown:

(1) J – Jet engine (without propeller)

T – Jet Engine (with propeller)

R – Rocket

PJ – Intermittent Jet Engine (Example: Buzz Bomb Engine)

RJ – Ram Jet engine

b. The odd numbers for the first and second parts of the designations will be used by the Army and the even numbers by the Navy. A particular engine will be identified by the same designation for both the AAF and the Bureau of Aeronautics. The number designating the engine type will begin with the number 30 in order to avoid confusion with some Navy airplane designations in which the new letters are used. Examples of this system are as follows:

(1) J31-1 – First Army model of first Army type of a jet engine (without propeller)

31-2 – First Navy model of first Army type of a jet engine (without propeller)

J31-3 – Second Army model of first Army type of a jet engine (without propeller)

J30-1 – First Army model of first Navy type of a jet engine (without propeller)"

The USAF "T.O. 21M-HGM25A-1-1 Technical Manual Operation and Organizational Maintenance HGM-25A Missile Weapon System" defines the first stage engine in paragraph 1-243 (page 1-101) as: "STAGE I ROCKET ENGINE. The Stage I rocket engine, designated LR87-AJ-3, consists of two engine subassemblies."

The designation means Liquid Rocket #87 AeroJet second USAF version. The first USAF version was the LR87-AJ-1, the third USAF version LR87-AJ-5 was used in the Titan II.

Any comments before I change the name to the proper one?

Mark Lincoln (talk) 02:23, 16 February 2016 (UTC) October 24, 2005 issue there was the last A
 * Support move - Looking at the sources, it's clear that "LR87" is the common name, which is given more weight on WP than official or "right" names (too much.weight in my opinion, but that's how the guidelines are currently interpreted). However, the move will have to be made by an admin, as the redirect page has been edited more than once. - BilCat (talk) 19:57, 16 February 2016 (UTC)


 * Move There is NO question that the proper designation is LR87, as US military engine designations did NOT use hyphens!!!--Petebutt (talk) 12:15, 29 January 2017 (UTC)

I decided this morning to search Aviation Week & Space Technology's archives to see when the "RL-87" first occurred. I searched for Aerojet LR87 and Aerojet LR-87. The results was interesting. The first mention of the LR-87 in AvLeak & Space Mythology was in the August 24, 1959 issue on page 27. "Models Show Configuration of Titan Engines." The caption mentions the "LR-87" and "LR-91." The last article in the AvLeak archive was "Titan, Adieu" covering the last Titan launch. The article in the October 24, 2005 issue reported "The flight also marked the last mission for the . . . Aerojet LR87 and LR91 series rocket engines . . ." In the intervening 46 years I found many mentions of the "RL-87 and LR87 (and LR91 & LR-91) their was no consistency. The same was true with the Atlas's LR89 & LR105 - worse actually because AvLeak usually used the Rocketdyne designation for the whole propulsion package (MA-3, MA-5, etc). I wonder if Aviation Week started the whole confusion?

Mark Lincoln (talk) 23:04, 17 February 2016 (UTC)

The LR87, is it unique?
The Titan 3M was about to be built when MOL was canceled. NASA considered using it as a vehicle for an enlarged Big Gemini 120 for space rescue. The The 3M would have had a quicker response time compared to the Saturn IB. "Extremes of estimated time interval to reach an emergency site in a low earth orbit are 4 hr. minimum and 144 hr. maximum. Another scheme was to use it to boost refurbished Apollo Command Modules for space rescue. NASA estimated Titan 3M would be cheaper, $15-16 million vs Saturn IB at $28 million. The 7 section solid strap on was tested. The modified LR87 had been successfully tested. Ground Support Equipment was built The fuel used in the modified YRL87-AJ-11 was "Alumazine 50 "a suspension of powdered aluminum in (gelled) Hydrazine.". The last cited article also explains the "M" in Titan 3M. It stood for "Metalized." The new fuel required modifications to the YRL87-11 which are detailed in the "Stage I Engine Demonstration Testing" report.

This would make the LR87 unique in being the only Large Liquid Propellent Engine to have been fired with four different Oxidizer/Fuel combinations. Anyone have more information on the "almost flew" YLR87-11" for the Titan 3M (or IIIM)*?


 * Aviation Week always called the SLV "Titan 3M," the only references to a "Titan IIIM" were official documents dealing with the development of the propulsion system.

Mark Lincoln (talk) 03:30, 18 February 2016 (UTC)

I have located the patent for the metalized gel fuel. Patent 3,607,470 is titled "Thixotropic gelled liquid rocket fuel containing hydrazine and aluminum hydride coated with a semicarbazide copolymer" The patent says the inventor was James M. Lucas El Dorado Hills, Calif., and it was assigned to Aerojet-General Corporation El Monte, Calif.

A careful (and tedious) reading of "Stage I Engine Demonstration Testing" left me certain that the modifications were to increase thrust and man rate the engine. I have turned up no evidence that the modified YLR87-AJ-11 was ever fired with Aumazinen 50. There has been a lot of research going on with gelled fuels.

Mark Lincoln (talk) 20:45, 22 February 2016 (UTC)

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Requested move 29 January 2017

 * The following is a closed 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: Moved. unopposed. (non-admin closure) Dicklyon (talk) 01:51, 11 February 2017 (UTC)

LR-87 → LR87 – US military engine designation did NOT use hyphens Petebutt (talk) 12:08, 29 January 2017 (UTC)


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Actual Designation
As always with the Wikipedia some individuals are of the opinion that the actual designation is not acceptable because they prefer an imaginary one. Military rocket and jet engines have no hyphen between the letter and numbers. The J57 was never a J-57, nor the LR87 ever a LR-87. It has long been argued by self-appointed idividuals, who make up designations to suit their individual desires, that the imaginary world in which they live rules. This does not only happen with engine designations. The same fantasists also ignore the British official system for designating airships with a R separated from the number by a period. As they are self-appointed mavins there is no reasoning with their silliness. So the Wikipedia has designations which are absolutely wrong as demanded by individuals who believe that "reality" has to meet their deires rather than what is the truth. This is an interesting situation for what aspires to be an encylopedic resource.

Mark Lincoln (talk) 22:26, 22 January 2022 (UTC)


 * In an entry above it says that the article was moved to LR87 but I can't see that happening in the edit history? There is naming inconsistency across rocket engine articles which ought to be addressed (or explained at the very least). For rocket engines that powered aircraft (within the scope of the aircraft engine task force) the convention is manufacturer/designation/name (if it has one) or manufacturer/name (eg. Reaction Motors XLR99 and de Havilland Sprite). This matches the piston engine/gas turbine engine naming convention. The spaceflight engine articles have mostly been passed over due to lack of sources and knowledge (in my case at least). I can try to help if needed. Nimbus (Cumulus nimbus floats by)  16:05, 23 January 2022 (UTC)
 * I agree on the oddity of a requested move being supposedly done in February 2017, semingly without being actually performed. I've boldly moved it since it seems all three of us are in agreement. – Anon423 (talk) 10:45, 24 January 2022 (UTC)
 * P.S. At least, we agree that the name should not have a hyphen. If you think it shouldn't be Aerojet LR87, I apologize for assuming incorrectly. – Anon423 (talk) 10:53, 24 January 2022 (UTC)