Talk:Rotary engine

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Various discussions[edit]

I'm having a hard time grasping how the engine works. An inside cutaway would help tremendously. -- 15:32, 20 November 2006 (UTC)

Just imagine a normal radial engine, except fix the crankshaft and attach the propeller directly to the engine block. (talk) 20:27, 11 January 2008 (UTC)

See also Talk:Rotary engine (disambiguation)

For clarity, I am removing the bullet from the fourth paragraph in the history section starting with "Another advantage, not realized at first"

In the history section, it says Balzer was interested "for two main reasons:" and then lists 3 bullet points. The third point is described as an "advantage, not realized at first", making it seperate from the reasons Belzer was first interested in the design.

The whole Balzer bit seems odd to me- if he was making these in the 1890s why was he concerned about the speed of aircraft, when it was about 10 years before powered flight began. — Preceding unsigned comment added by (talk) 16:51, 5 May 2012 (UTC) 02:55, 7 January 2006 (UTC) Shimonyk

The Mazda mention at the bottom is out of place, isn't it? That's a pistonless design, as seen here:


The next major advance in the design was Louis and Laurent Seguin's Gnome series from 1908. Believed to have been inspired by the American Adams-Farwell automobile's rotary engine concept, they started their development with the seven cylinder Gnôme Omega No.1,

I'm almost certain this is wrong. The Gnome originally started as a German engine, the Gnom, which was a single-cylinder stationary engine for industrial use designed by Oberussel. The Seguin's basically adapted the Gnom design into a rotary. I don't see where the Adams-Farwell concept comes into it. Maury 22:20, 22 February 2006 (UTC)

Radial, not rotary[edit]

This engine is called a Radial engine, not a rotary engine!

Nope, it's a rotary engine. It's rather different operation than a conventional radial (as you would know if you had actually read the article instead of vandalizing it). This was the original rotary engine. Wankels and other pistonless designs are at fault for creating the naming confusion because they adopted a name that had already been in use for some 50 years. - Emt147 Burninate! 07:00, 17 March 2006 (UTC)

  • Actually, I think it is called the Radial Engine and not Rotary Engine. I have an old book back home from the Shuttleworth Collection which refers to this type of engines as Radial Engines. You can also see here that the engines are called Radial Engines.

    The article is also rather confusing by saying that Rotary=Radial and Other Types of Rotary=Wankel Engine. In that case, what exactly is the definition of Rotary Engine?

    Also, have a look at what has to say about rotary and radial engines:
    *Radial Engines
    *Rotary Engine

    In my understanding, a Radial engine is an engine where all the pistons share the same hub on the crankshaft. A Rotary engine on the other hand is a type of engine that does not utilise pistons to generate power, using rotors instead.
    --Pavithran 18:20, 25 September 2006 (UTC)
Sorry, you're wrong. And I say this as someone who has actually run at least one example of each of the engines you are talking about.
You are apparently confused because rotary piston engines look extremely similar to radial engines. You cannot easily tell the difference from a photograph. In fact, you stated above that rotaries are actually radials and then linked to a page showing how a radial works. You will note that that animation does not have spinning cylinders, and thus is not a rotary. I assume your book from Shuttleworth is a similar confusion, but I cannot be sure.
All rotary piston engines are a subclass of radial. The distinction is that in the rotary the cylinders spin, and in a radial they do not. On the other hand, pistonless rotary engines, or Wankles and their work-a-likes, are very different designs. It is too bad people refer to these as rotaries, but that's just the way it is. They could have just as easily referred to jet engines this way, but luckily rotaries were not long forgotten in the 30s like they were two decades later.
The article is correctly named. Maury 21:24, 25 September 2006 (UTC)
Mr. Maury is correct about this. Gzuckier 21:42, 25 September 2006 (UTC)
  • I see, so you mean there is a different kind of engine altogether called Rotary Piston Engines and these engines look similar to Radial engines but work differently ?

    Okay, in that case, could you give me a source that explains how these Rotary Piston Engines work?

    Also, what do you mean by "spinning cylinders"?
    --Pavithran 06:59, 26 September 2006 (UTC)
Yes, I know the naming is very confusing! Here's an animation of how the Gnome works, the Gnome is sort of the canonical rotary: Gnome. If you look at the shaft you'll notice the actual operation is identical to the radial, the pistons have the same operating cycle and layout. The only different is what part moves and what part is bolted to the aircraft. If this link is not in the body of the article, it should be! Maury 12:31, 26 September 2006 (UTC)
  • Wow! Fantastick link there Maury. Great job indeed. I have e-mailed the owner of the website to request for permision to use that image on Wikipedia. Hoping to hear from him soon. If he agrees, we can start editing the article to properly explain the confusion between Rotary and Radial. Apparently, the rotary engine that is shown in the first pic of the article is called Gnome Rotary Engine.

    --Pavithran 19:42, 26 September 2006 (UTC)
No problem! It's the Gnome that I have actually seen running. It may have been a replica actually, but I don't think so. Maury 21:33, 26 September 2006 (UTC)
  • Okay, bad news, the owner of the website does not want to allow use of his material on Wikipedia, so this means we need to find an alternative. --Pavithran 20:59, 27 September 2006 (UTC)

Just to keep adding to debate: The rotary piston engines _most definitely_ are radial engines. In evidence: Definition of "radial" from Wiktionary states: 1. arranged like rays that radiate from, or converge to a common centre. Definitely applies (just as it would to a starfish, whether it spins or not). Also, from "The Rotary Aero Engine" (Andrew Nahum, &copy The Trustees of the Science Museum 1987): "The rotary is a special form of air-cooled radial engine... ... for an aero engine, the radial arrangement has several advantages." I, too, have been around a few, most notably with Kermit Weeks. I take no issue with anyone who differentiates the classes by referring to these as "rotaries", while calling the stationary models which grew into behemoths and are still widely used simply "radials". I do, however, take exception when someone wrongly affirms that rotaries are not radial, just because one has run them. I never ran one, but have worked on one, and as neither running one nor working on one gives one the insight to discard simple scientific definitions, I would submit that the article be changed to reflect that a rotary is a type of radial, today very rare, and for motives of simplicity and clarity they generally are not called "radials", in spite of technically being so.Chrisklinger (talk) 01:06, 27 December 2008 (UTC)

Thanks for your souces, Chris. I've no problem adding that into the article. However, the argument usually made here, though it's not explicit in this section, is that the only type of rotary engine is a Wankel type, and that what is called a rotary engine here is just a misnamed radial. It is in that context that the statements that the rotary is not a radial were made. - BillCJ (talk) 02:37, 27 December 2008 (UTC)
To further expand, every so often this article is edited by the Mazda afficianados whose only concept of a rotary engine is of the Wankel type. They take one look at the Lead image, and conclude it's a stationary radial engine. They don't realize that the rotary-radial is at least 60 years older than the Wankel, and has been called a "rotary engine" all that time! - BillCJ (talk) 03:07, 27 December 2008 (UTC)

Newer comments[edit]

Folks, wouldn't it be better to acknowledge that, whatever the original usage of the term, when the overwhelming majority of people say "rotary engine" they do not mean any engine with pistons. They mean an engine like the Wankel or the new LiquidPiston X Engine. They will call an engine with pistons arranged around a central hub radial. This page is the first time I personally ever saw any different usage, ever. Engineers, pilots and flight mechanics included. The terms perhaps have changed their meanings, but attempting to change it back will only cause endless, pointless debate. Please bow to modern convention. Ernest Ruger (talk) 18:50, 21 November 2014 (UTC)
No, rotary engines in actual use are predominantly the rotating cylinder radial engines used in Great War aircraft, just as described here. Pistonless rotary engines (which already have a conveniently named article) have included the Wankel engine and sundry products from the world's snake oil vendors that went nowhere. We do not need to rename Wankel engine as anything else, certainly not anything rotary. The DKM Wankel (which is a rare prototype amongst obscure engines) rotates, but the KKM Wankel, the only (pistonless) "rotary engine" with any claim to being more than a handful of examples, doesn't even rotate!
Good and clear policy to avoid article churn already warns against renaming topics to follow fashions. Not only that though, the rotary engines of the Great War are still the only rotary engines with any significant claim to the name. Andy Dingley (talk) 19:13, 21 November 2014 (UTC)
This type of engine has never been referred to as anything but a rotary engine. We can't invent a new name for it just to suit a supposed 'modern convention' for which nobody has provided a source, and which basically denies significant historical usage. We have a disambiguation hatnote for anyone looking for other types of engine (usually referred to by their specific name anyway), and that is all that is necessary. AndyTheGrump (talk) 21:54, 21 November 2014 (UTC)
A person's primary definition of "rotary engine" probably depends partly on whether a person is more interested in automobiles or in aviation. Most modern car afficianados, which the recent IP probably is, have no clue that there is any other type of rotary engine other than the Wankel and other similar modern engines. So it's quite a shock to them to find out that there is another type of rotary engine that's been around for over 100 years, and it's not a Wankel! Worse for them, the Wankels aren't even covered at the title "rotary engine". The older engines are sometimes refered to as "rotary radial engines", but certainly not as much as the simpler term. From a Google seach, "rotary combustion engine" appears to be more common for Wankels and the like than "pistonless rotary engine", but "rotary engine" is most common for them too. So that leaves us with the question of which engine type is the primary topic, and I'm not certain there really is one. BilCat (talk) 00:22, 22 November 2014 (UTC)
This one has raised so many responses precisely because the original query is both sincere and thoughtful. None the less it is still wrong-headed - a Wankel Engine is generally called a Wankel engine - the other engines that might be (and occasionally are) called rotaries also have their own unique names. We could call "our" rotary engine (i.e. the subject of this article) a "rotating radial", or a "piston rotary" – the point is that no one ever has, so we would be using an invented term to name an encyclopedia article rather than the "natural" one - at best a silly sort of thing to do.
If you had never heard of this type of engine then coming across it might be a bit of a shock. There seems to be a gut reaction, either conscious or otherwise, that says something like : "This article is about something I never heard of before – clearly it doesn’t really belong here at all, the least they could do is hide it away under another heading! – I don’t look up an encyclopedia, of all things, to be confronted with unexpected information". For me, the more shocks like this I get the better, the whole idea of something like Wikipedia is learning stuff. If my own prejudices get confirmed along the way that may be a bonus, but it certainly isn't the main point (I hope).
The term "rotary engine", like many other article titles, IS ambiguous - because some very different engines are also (sometimes) called rotaries. Disambiguation between different articles that might cause confusion due to identical or very similar names is a totally different question - I honestly think that we cover this particular ambiguity reasonably well, with hatnotes, disambiguation articles and so on. There is no complaint here (I hope) that someone wasn’t able to find the information they wanted because this article was confusingly mistitled. --Soundofmusicals (talk) 05:21, 22 November 2014 (UTC)

Clarifying Paragraph[edit]

  • I've added a section at the end of the article clarifying the difference between Radial engines and Rotary engines. --Pavithran 23:26, 27 September 2006 (UTC)

Westinghouse and the Rotary steam engine[edit]

Should G. Westinghouse and the Rotary steam engine direct here? J. D. Redding

I came here due to that link and would like to find out more about Westinghouse's engine, whether it is rotary in the same sense as other engines discussed in this article.--Jrm2007 (talk) 20:21, 11 May 2010 (UTC)

Sopwith Camel[edit]

There's a reference in the article to the Sopwith being 'notoriously dangerous' - there's a lot of discussion about the handling characteristics of that aircraft on the talk page relating to the Camel. This particular phrase, I think is far too simplistic and should be removed if it can't be specifically verified. Scoop100 (talk) 12:46, 26 April 2008 (UTC)


What does the Rotary engine emit, i.e. CO2? —Preceding unsigned comment added by Indexdozen (talkcontribs) 20:28, 26 April 2008 (UTC)

It is a VERY dirty engine - emitting (besides large quantities of the all the usual piston engine nasties) large quantities of unburned and half burned fuel and castor oil. Just as well, from the environmental point of view, anyway, that they're no longer in use!!! --Soundofmusicals (talk) 02:08, 6 November 2008 (UTC)

Rotary Engines - Castor oil, diarrhea, throttle, gyroscopic forces, and the blip-switch[edit]

A recent editor states: "I don't think there is very much doubt that pilots of rotary engined aircraft inevitably ingested castor oil - nor what the medical effects would have been!"

Chad Wille, Director of Maintenance at Old Rhinebeck Aerodrome, disagrees.

Mr Wille states as well that the engines were not "unthrottleable" and did not have terrible torque effect. Mr. Wille's comments are buried in the middle of a lengthy article, but he states that these are myths and are the result of dramatic embellishment in 1930's pulp magazines written by men who never flew behind a rotary engine. He asserts that, while the engines do throw a castor oil mist, it is not enough to effect a pilot. He also states that torque and gyroscopic precession are hardly felt on the le Rhone 80 hp, even in very small airframes like the nieuport 11, and the gnome 160 hp does not affect the planes in ways that mild control pressures (far less than the effort required when flying the plane in a crosswind) cannot correct.

Rotary engines actually did have a throttle of sorts: Mr. Willes states that rotary engines are not "unthrottleable", as is asserted in the section concerning use of the blip switch. He states that all rotaries have two piece air/fuel throttles that, once understood, act very much like their modern single-piece counterparts and allow single lever graduated throttle response from idle to full speed. He does support the wiki article's statement regarding the Gnome monosoupape which had a cockpit switch allowing the pilot to run on 1, 3, 6, or all 9 cylinders.

Use of the Blip-Switch: Mr Wille writes that factory manuals often discouraged cutting the ignition dead by use of the blip switch and emphasized the use of the throttle instead. He states that the blip switch is more frequently used today due to modern air-fields which don't always allow aircraft to land directly into the wind, unlike WWI fields which generally were large and square. The instant and full bursts of power allowed by the ignition-shorting blip switch (with the fuel/air throttle set in the right place for full power) allows the pilot to put a blast of air over the plane's control surfaces to help with steering to a stop. He states that modern pilots of these old an valuable aircraft land "on the blip" for the extra margin of safety and control since it frees the pilot from having to fiddle with mixture lever in any way during landing.

The above has been paraphrased from: —Preceding unsigned comment added by SonjaZ (talkcontribs) 19:31, 30 April 2008 (UTC)

Wow, erm, okay. Someone really needs to go in and clear up this stuff as the article is a mess right now. The refs are poorly formated for a start and I don't think I'm awake enough to want to face trying to dig stuff out. I suspect more refs are needed for big chunks of this too. Anyone up for a project? :-) Caomhin (talk) 21:12, 30 April 2008 (UTC)
Right, some extra reading. The Aircraft Engine Historical Society support the Castor Oil stuff in an article by Kimble D. McCutcheon (which actually includes third party reference too!) gets referenced in a few places too and they also claim the oil mist was enough to affect the pilots. Other sources seem to make no reference either way. It seems best to leave this logic open while more sources are gathered.
Throttle-wise. I believe the last edit makes the situation unclear. The article originally stated that the Gnome has no throttle which Chad Willie agrees with, the Gnome has a faux-throttle which killed certain cylinders. The very sources given to claim that "all" rotaries had a normal throttle states quite clearly this isn't true, as does every other source that is within easy reach. In fact the edit itself contradicts itself by then commenting on this cylinder shutdown replacing a standard throttle on some engines. It seems like violent agreement in logic but confusion over the ways of expressing the matter - a recipe for disaster :-) Basically it seems that this part simply needs tidying to use language which is slightly clearer.
Just a personal opinion Caomhin (talk) 21:54, 30 April 2008 (UTC)
1. The laxative effect! This actually looks VERY likely - Mr. Wille's comments notwithstanding. Just because the rotary engines he is responsible for haven't given him the "runs" doesn't mean they didn't give them to pilots "flying behind" engines subject to the varied loads of combat flying. In any case it is just one source against another. It just makes sense that sitting in a fine mist of half-burned castor oil in a 100 mile an hour split seam for an hour or two it would be hard not to end up swallowing a bit! (Perhaps someone needs to actually try???) I'm sure you could build up quite a pile of references in support of this (NOT all of them on the web).
2. The throttle question - of course only the monosoupape rotaries had NO throttle (except for ignition cutting). The others had have throttles, and this does need to made clear, although how immediate and precise throttle response was is another question. Genuinely contemporary sources do however refer to "blipping" when landing. Many wartime (1914-18) aerodromes were very small and confined indeed - others had narrow cinder runways because the grass surface was too soggy or otherwise unusable. These would have been plenty of motivation for pilots of the time to have used blipping for the same reasons modern pilots of vintage rotary-powered aircraft do. The "blip" switch (a little press button on top of the joy stick) was there to use!
3. The gyroscopic effect. This apparently was mainly effective in sharp turns, the nose used to kick up in a turn in one direction and down in the other. It was also much more marked on some types than others. The Camel was for instance notorious - whereas people habitually described the Pup as "delightful to fly". All this is actually quite consistent with Mr Wille's remarks - the torque in level flight probably wasn't THAT much more marked than other propeller aircraft - especially with the smaller rotaries.
Finally - yes you do have to watch out for hyperbole in sources on WW1 a/c - especially those originating in the period from about 1920 to 1960. Most of this is pretty easy to pick, however - what I call the "Boys Own Weekly" prose kicks in and you know you mustn't take anything too seriously. Soundofmusicals (talk) 01:19, 1 May 2008 (UTC)

On the laxative effect (not a very good band, by the way) - I'm not so certain that it was all that likely. Apart from Mr. Willes (who appears to be a pilot himself:, the people at Rhinebeck Aerodrome, which has one of the largest collections of early aeroplanes in the world, have been restoring and flying WWI era aircraft with a variety of rotary engines (Gnome/Le Rhone/Oberursal, Clerget, Bentley, Siemens) for almost 50 years. One would think that they would have corrected the assertion Mr. Wille's makes on their website that the castor oil mist emanating from the engines does not "move the bowels." These people have first-hand experience flying aircraft with these engines. Consequently, they warrant a significant degree of credibility when discussing the characteristics of the engines.

Use of the blip-switch - the planes had them for a reason, and there's no reason they couldn't have been used by pilots then just as they are used today. Despite this, Mr. Wille clearly states in no uncertain terms that all rotaries, with the exception of the monosoupape, have two piece air/fuel throttles and that the factory manuals often emphasized the use of the throttle in lieu of the blip switch. He admittedly does not give line and verse of specific manuals on this point and does not provide pdfs of them in this article, but that would be asking a bit much.

—Preceding unsigned comment added by SonjaZ (talkcontribs) 04:26, 1 May 2008 (UTC)

I'm sure you'll all hate me but I've tried to clarify a bunch of stuff. If we could try to avoid any major edits which change the meaning without prior discussion for a little while I suspect that would help. If I've screwed something up badly then give me a poke and I'll happily try to fix it.
Re: laxative - I have to say that logic falls squarely on the idea that it was an issue. Maybe not on short flights and it's probably been exaggerated, but I suspect it was a factor. Mr. Wille is the only person to make reference to it not being an issue in my brief hunt, others either remain silent or say it was a problem. I suspect the silence is taste related. "Race with the Wind: How Air Racing Advanced Aviation" By Birch Matthews (ISBN:0760307296) describes a "laxative mist" on p130 although I think my favourite wording was "It is said that a pilot who spends many hours breathing unburned Castor oil never suffers from constipation." from
So yeah, I think it sounds reliable and that we can find sources to back it up. Maybe more are needed but a lone dissenting voice does not a true argument make. I've left it off for now though as I suspect we'll lean towards edit wars if this isn't agreed beforehand.
Caomhin (talk) 07:46, 1 May 2008 (UTC) (Off to find The Laxative Effect's awkward second album)

It's a decent point that some pilots may not have mentioned a laxative effect due to it being in poor taste and this makes it difficult to verify that the engines did or did not make one sick. However, the key difference in the documentation provided here is that of first-person testimony versus hearsay. Mr. Wille and the Old Rhinebeck organization, whose site is running the article which states these claims are popular myths, have a great deal of first-hand experience maintaining these engines and flying them in vintage aircraft. The stuff I read while growing up(as well as the documents cited here) which say it was a problem do not cite to any verifiable first-hand accounts or personal experience in support of their assertions. In short, to refute the first-hand evidence from Rhinebeck stating that the castor oil mist is not a problem and that all rotary engines have a throttle (including the monosoupape, though its throttle consists of a cylinder switch), the best evidence would be a first-hand account from a pilot of a rotary-powered aircraft who says he had a problem with the castor oil making him ill or that the engines didn't have a throttle. Second-hand accounts by people who never flew the aircraft are not as convincing as statements by people who have, no matter how many second-hand accounts there may be, and a falsehood stated repeatedly is no more true than when it was first told.

This is entirely speculative, but one would think that if a person were inhaling castor oil in such a quantity that enough of it was reaching their bowels to cause diarrhea, a person would also complain of serious respiratory problems due to the oil in their lungs.

I would also like to let it be known that if someone will fly me around in a two-seater powered by a rotary engine, I consent to be a guinea pig in the interest of wikipedia (but only on this point). SonjaZ (talk) 14:31, 1 May 2008 (UTC)

Sorry but Rhinebeck do not say that all rotaries have a throttle. "The exception" are the exact words used on that article, that is expressly saying that the Gnome doesn't have a throttle. And it should be noted that no other source appears to contradict this point. The cylinder cut-off trick isn't an actual throttle, merely a way to vary power delivery.
With regards to the laxative effect you'll also note the article makes no current statements about this. There is enough logic behind the comments that it is plausible there could potentially be some truth behind it. However everyone agrees the need for more reliable sources. There are a variety of sources that support the laxative argument however none of a high enough confidence to use. It should also be noted that Chad Wille alone doesn't not qualify as enough evidence. The argument in either direction needs multiple, concrete sources (i.e. pilots during the war) before anyone even considers reinstating this as a fact either either way. At absolute most we could have a reference to the fact that there is disagreement over the issue.
I think re-iterating these points gets us nowhere. Until anyone can find more sources that comment either way it's a largely dead issue.
Caomhin (talk) 20:02, 1 May 2008 (UTC)

The Rhinebeck site says:

"[W]hoever started the rumor that rotary engines are unthrottleable should be throttled! In fact, all rotaries have two piece air/fuel throttles that act very much like their modern single piece counterparts once they are understood. They allow single lever normal throttle response from idle to full speed and anywhere in between. The exception to this is the Gnome Monosoupape, which has a clever pilot controlled cockpit switch allowing it to run on 1, 3, 6, or all 9 cylinders giving a fine variation in power output, just like a throttle. "

It also states:

"It does throw a castor oil mist, leaving that wonderful smell many know from days of model airplane engines, but not enough to effect the pilot.", accessed 2008-5-01.

SonjaZ (talk) 20:26, 1 May 2008 (UTC)

Sonja - I read the article. I read that section, I even quoted it in my last comment. "The exception" and "just like a throttle" (emphasis both mine) state clearly it is not an actual throttle. You're quoting something which explicitly disagrees with your argument. We all agree it gives the same abilities as a throttle, but it isn't technically a throttle. Now please stop talking to me like I'm an idiot and stop spamming that URL all over the shop, we know it exists. And I repeat, simply quoting Chad Wille again and again does not make him become multiple sources. We know he says it's not an issue, it's the main reason the article makes no comment either way right now. Please find another source to support his comments. Caomhin (talk) 20:38, 1 May 2008 (UTC)
A further point about the "selective cut out on a mono rotary - while the ignition to those cylinder was cut the fuel/oil mixture was not! So the use of the device just as if it were a throttle was asking for an engine fire!! Managing a rotary engine in flight was actually a good deal more complex and fiddly than a "stationary" engine, even a 1915 example of the species (I have a good "book" source on the problems that I will be rereading when I have a spare hour or two). I also own a vintage college engineering text on aero-engines that describes the old rotaries from a purely technical point of view that I will dig out.
The article (apart from the initial definition bit) is a horrible mess at the moment - and needs a COMPLETE rewrite - togther with references and subheadings to break up that great block of text. I think as a general rule when two or more more or less equally creditable sources diametrically disagree we need to take both into account. Even something like "while (source A) claims ... (source B) states...". I am planning to do this, if no one else jumps in first (please please...)
On blip switches - pupils were strongly discouraged from using the blip switch to turn off the ignition after landing - but to use the master switch on the dash instead (and yes, I have a source for that one too) but apparently almost no one used the throttle on a rotary for landing - it was just too fiddly (remember the mixture control had to be adjusted with the throttle itself), especially at a time when you were involved in the most difficult part of a normal flight, getting one of those hairy little machines to land without turning over. Soundofmusicals (talk) 23:41, 1 May 2008 (UTC)

This is a VERY old topic, but I think it is worth putting this post here all the same. I have just been reading a newly released book by Arthur Gould Lee (bless him) who actually flew Sopwith Pups and Camels in France under wartime conditions. With due respect "Chad Wille, Director of Maintenance at Old Rhinebeck Aerodrome" had no idea what he is talking about (so far as rotary engines making pilot shit themselves is concerned, anyway). Lee makes it very clear that pilots of rotary engined aircraft had to be very careful of their diets (avoiding fruit and other healthy, high-fibre food, and to drink "stiff doses of chlorodyne" before going on long patrols, especially at high altitide. Lee goes as far as to hint about the difficlties of being (in spite of all precaution) caught short in the air! I have changed the article, adding the relevant reference. SO THERE Mr. Wille, and every other revisionist who would like to cast doubt on important (if rather embarrasing) information. TRUTH RULES!!! (I'm really, really chuffed about this!!) --Soundofmusicals (talk) 04:09, 13 November 2012 (UTC)

  • A further point - it is of course far from uncommon for aircrew (and soldiers and sailors for that matter) to "shit themselves" in combat with pure terror (no disgrace by the way - a purely physiological reaction). At least we now know that pilots of rotary-engined fighters in WWI had a great excuse! --Soundofmusicals (talk) 04:09, 13 November 2012 (UTC)


The following paragraph from the Description section refers to the lack of throttle on these engines and mentions a "rotary selection switch" for the Gnôme Monosoupape in the Fokker Eindecker.

With no throttle, the engine was controlled by cutting the ignition; "blipping" the engine on and off using the "blip switch" gave the characteristic sound of the engine, almost as though it was stalling. A few 9 cylinder rotaries had a partial "throttle" functionality by switching off some, rather than all of the cylinders; typical configurations could run on 1, 3, or 6 cylinders.[4] The Gnôme Monosoupape series possessed this feature, and some documentation regarding the Fokker Eindecker shows a rotary selector switch to cut out a selected number of cylinders suggesting that German rotaries did as well.

However in the German Wikipedia article on the Gnôme Monosoupape here (German Monosoupape article) mention is made of a "control wheel" for adjusting the engine power. I include the original text followed by my (free) translation:

Die Leistung ließ sich nun, im Gegensatz zu den Vorgängermotoren, mit Hilfe der Hubverstellung der Auslassventile weitgehend regeln, was mit Hilfe eines kleinen Handrades im Führerraum geschah. Damit konnte einmal das Verhältnis von Kraftstoff zu Luft der Flughöhe angepasst oder die Leistung durch ein mageres Gemisch verringert werden. Damit war erstmals ein Umlaufmotor in Grenzen regelbar.

"In contrast to previous rotary engines, the Monosoupape's power could be controlled by means of a small rotary switch in the cockpit, which adjusted the stroke of the exhaust valves. This permitted the fuel-to-air ratio to be adjusted to suit the altitude or the power to be reduced via a leaner mixture. This was the first rotary motor which could be adjusted to a limited extent."

Perhaps this is the function of the "rotary selector switch" mentioned above. Unfortunately, German Wikipedia does not rigorously enforce the WP rules on referencing verifiable sources, so this information has to be taken on trust. If true, it throws a new light on the throttle/'blip' discussion. --TraceyR (talk) 08:43, 26 September 2008 (UTC)

I found a decent description of the Monosoupape's variable valves, which I have incorporated (with a reference). Salmanazar (talk) 14:06, 26 September 2008 (UTC)
All German rotaries (with the exception of the Siemens-Halske SH.III) were either licensed or direct copies of French Gnome engines. Their workings were more or less identical.
As for the throttle issue, Monosoupape engines didn't have a throttle, but some rotaries did have a proper throttle such as the Clerget and its derivative the Bentley BR.1 and its big brother the Bentley BR.2 (used in the Sopiwth Snipe). Those engines were throttled by adjusting the fuel/air mixture instead of cutting out cylinders, though they did still have the blip switch. (talk) 13:42, 6 April 2010 (UTC)

Early form of ... aircraft engine[edit]

The intro states that the rotary engine was an "aircraft engine", whereas it was apparently first used on motorcycles before powered flight had been achieved. Perhaps the summary should state as much. Any thoughts? --TraceyR (talk) 21:27, 27 December 2008 (UTC)

"Revolving cylinders"[edit]

The text of the disambiguation link describes the rotary engine as having "revolving cylinders". Wouldn't it be better for it to say something like "... with radially-mounted cylinders rotating about a fixed crankshaft"? Admittedly it is more long-winded but it is also more accurate. Any objections and/or alternative suggestions? Thanks. --TraceyR (talk)

People have been objecting that the disambiguation link is too long winded already! The main point is that we are not talking about the Wankel "rotary" here - I think provided that is clear the shorter the better. On the other hand "revolving cylinders is very ambiguous - in fcat the mind boggles! I have changed this to "cylinder block". Does this meet with approval? Although it is LONGER(!?)--Soundofmusicals (talk) 20:25, 28 December 2008 (UTC)
Length shouldn't be an issue here - Pistonless rotary engine has a much longer text. "Revolving cylinders" conjured up weird visions; the present text is a big improvement! Would "rotating cylinder block" (to echo the engine type) be even better? --TraceyR (talk) 11:45, 29 December 2008 (UTC)
"Rotating" let it be! A bit of a play on words, but so what? They're there to play with!--Soundofmusicals (talk) 21:03, 29 December 2008 (UTC)

"Rows" in rotary (and radial) engines[edit]

Many radial and some rotary engines have two "rings" of cylinders. These rings are actually called "ROWS" - I suppose it does sound illogical, but that's what they are called. If you don't know something - query it on this page rather than rushing in to edit the article page. Some bad edits escape the notice of others - and bring down the quality and usefulness (not to mention the reputation) of Wiki as a whole. --Soundofmusicals (talk) 09:39, 13 November 2009 (UTC)

Cylinder block?[edit]

There are numerous instances of the phrase "cylinder block" in the article but rotary engines do not have a cylinder block. Each cylinder is a separate object, they are not set into a "block" at all. Roger (talk) 11:01, 16 August 2010 (UTC)

So how would you describe the (rotating) body of the engine? --Soundofmusicals (talk) 05:20, 17 August 2010 (UTC)
How about simply saying "the engine"? Except for the crank, and a few other minor bits, basically the entire engine spins. Roger (talk) 06:57, 17 August 2010 (UTC)


Discussion of Siemens-Halske style geared rotaries - with the engine rotating in the opposite direction to the propeller, probably needs to be more comprehensive, cited, and placed in the "history" section. I have never seen this type of engine described as "bi-rotary", at least in English. --Soundofmusicals (talk) 00:01, 27 February 2011 (UTC)

Bi -rotary engines[edit]

Sorry for my English but my native language is dutch.

Were do bi-rotary engines fit in this article.

The Siemens-Halske Sh.II is a bi-rotary or a "differential" rotary.

A further development took place during WOII resulting in a bi-rotary with " open top" cilinders surrounded by a fixed ring.

It's a very rare engine and little info is to be found. Only those two articles : — Preceding unsigned comment added by Frdev (talkcontribs) 00:26, 27 February 2011 (UTC)

Rotary carburettors[edit]

It is impossible (just think about it for a moment) to fit a conventional float carburettor to a rotary engine. Carburettion (control of the mixture of fuel, air, and castor oil) which got into the cylinders through the only "stationary" part of the engine - the hollow crankshaft, was problematic in ANY rotary - although of course it was even more primitive in the Gnome "mono" engines - where a single valve took the place of both inlet and exhaust valves! Just pointing this out for the benefit of a good faith editor who wanted to change this in the article. --Soundofmusicals (talk) 21:38, 5 May 2011 (UTC)

Later rotary engines[edit]

The article seems to suggest that the engines didn't last long after the first world war. I suggest someone looks at the Bristol range of engines such as the Mercury (see Wikipedia entry)and makes some link to them. These were used in various aircraft in the second world war. — Preceding unsigned comment added by Epimandios (talkcontribs) 11:51, 8 January 2013 (UTC)

The Bristol Mercury is a radial engine, distinct from a rotary engine. Nimbus (Cumulus nimbus floats by) 12:26, 8 January 2013 (UTC)

Castor oil and rotary engines.[edit]

(the following was inserted into the main text of the article by a (possibly very new editor who did not realise the function of the talk page for (for instance) this kind of remark - to be fair, I have reinserted it here.)

This is not true and is a well worn myth. First off, you can direct the exhaust from a rotary engine in the same direction due to the fixed crankshaft. This allows you to have the exhaust directed downwards, allowing it to pass underneath the aircraft. Second, all rotary powered aircraft have a cowling fitted tightly to the fuselage. The would have an opening at the bottom of the cowling, or be in a horseshoe shape with the opening on the bottom. This was done to contain any excess full and oil that would inevitably get whirled around while the engine ran. Plus when you cut the ignition, it still would run fuel through it and this would end up being exhausted in an unburnt state, so you wanted all this to be contained as well. So you simply did not have all sorts of oil and exhaust getting blown back into the pilot and all over the plane, it just did not happen. Stories of pilots getting diarrhea after flying a rotary powered aircraft may have more to do with nerves, diet and the basic unhealthy conditions found at many airfields during World War 1. Modern replicas using rotary engines that are flown also disproves the myth that pilots got "bathed" in caster oil. They routinely fly these and do not end up covered in oil. This is one of the most persistent myths about rotary engines and it is simply untrue, despite stories to the contrary. [remarks inserted by I.P.]

Practically everyone writing at the time mentioned flying clothing of rotary engine pilots getting soaked in castor oil. Photographic evidence (especially of clear-doped aircraft such as Fokker eindeckers) shows how the oil stained the fuselages of aircraft using rotary engines (in many cases it's a matter of quite new aircraft being already extensively stained!). And we have (right here) a citation from a reliable witness that actual ingestion of the oil - particularly on a long, high patrol, regularly produced an certain embarrassing problem - speculative "original research" to the contrary remains speculative original research.
"Modern replicas" are much better maintained than in the stress of wartime (1914-1918 wartime at that). They are flown at lower altitudes, for shorter periods, and very much more gently (wartime combat needs to extract maximum performance no longer exist, and the engines themselves are now rare and valuable antiques rather than expendable war materiel). These factors, and possibly others, make the experiences of modern pilots flying behind rotary engines pretty much totally irrelevant. --Soundofmusicals (talk) 01:13, 22 February 2013 (UTC)
Here's a treat for you: [1] and part [2] and part [3] - engine is a genuine Bentley BR2. — Preceding unsigned comment added by (talk) 20:40, 31 December 2013 (UTC)

American radials[edit]

While rotaries continued in quite widespread service in the RAF in the immediate postwar period - as a powerplant for new aircraft they were superseded by the first (successful) generation of (British) air-cooled radials (see the "postwar" section of the article).

In American service the use of rotaries was limited to such types as the Nieuport 28 - the emphasis in America was very much on the famous Packard Liberty and other water-cooled "stationary" engines - and it was these (rather than rotaries) that were supplemented (and to a certain extent replaced) by the first successful (American) radial engines.

The relevance of the above is to my reversion of a well-meant edit equating the demise of the rotary in Britain with the situation in America. Rotaries really never took off (pun intended) on the left-hand side of the Atlantic - while a few imported examples may have been used for a few years the whole concept was long dead by the time the first American radials came out. --Soundofmusicals (talk) 04:45, 18 April 2014 (UTC)


What about the new ones? Like LiquidPiston X2? I can find almost nothing on them anywhere. Do they actually exist or are they a hoax that the tech media bought into? — Preceding unsigned comment added by Ernest Ruger (talkcontribs) 00:04, 21 November 2014‎

The LiquidPiston X2 doesn't seem to fit in with the description given at the top of the article: "a type of piston engine with a rotating cylinder block" - it is more closely related to the Wankel engine, having neither pistons nor cylinders. [4] Accordingly, it is off-topic for this article. AndyTheGrump (talk) 00:10, 21 November 2014 (UTC)
WP does have an stub article on that type of engine at Liquidpiston. It's also listed at Pistonless rotary engine. - BilCat (talk) 04:22, 21 November 2014 (UTC)

"Post-War" section[edit]

This was originally written simply to mention that rotaries were not used for new designs after 1918, although they continued in use (in older designs) thereafter.

Three apparent exceptions were added piecemeal by other editors - one of these simply indicates that the Swedes (and likely others) also used up their old rotaries on things like basic trainers. Another referred to the Michel engine, which was apparently designed as a (kind of) rotary, although the cylinders became "fixed" at quite an early stage, and the use of rotaries being somewhat incongruously applied to an experimental Soviet-era Russian helicopter.

I have (I hope) rather better integrated this matter into the rest of the section. --Soundofmusicals (talk) 05:46, 11 March 2015 (UTC)

"Power" and "capacity"[edit]

Are both things that can be measured, so that we can determine the ratio between them - but only in terms of standardised units, such as horsepower or kilowatts on one side, and cubic inches or litres on the other. So while it was a clumsy mixing of imperial measure and metric to talk about "horsepower" and "litres", it made much more sense than comparing "power" with litres"!! A choice here of changing it to "power", and "capacity", which would have been cryptic to a lot of people, or kilowatts to litres. Better (as the strange combination of hp and litres is actually continued in the next sentence anyway) to be less than specific about the actual unit of power we are talking about? -Soundofmusicals (talk) 13:17, 25 August 2015 (UTC)

Rename to Rotary engine (aircraft)?[edit]

Would the perennial confusion (as has arisen again recently) between the aircraft-specific types and the generalised non-reciprocating rotary engines since James Watt's day be made clearer if we moved this article to a more specific disambiguated name, and moved the disambig page to Rotary engine? Andy Dingley (talk) 08:44, 5 April 2016 (UTC)

The idea has of course been mooted before (mostly by people who want "rotary engines" to refer to Wankel engines). Main difficulty is that (aircraft) is not the defining distinction (cars, motorbikes etc. have also used engines of the type described in this article, albeit very rarely). Technically more accurate (or specific, anyway) headings, like say Rotary Engines (reciprocating) might be devised - but one wonders very much if any such heading would deflect much of the confusion. Looks more confusing rather than less to me. Might one just gently and kindly ask that people who set themselves up to begin to edit an encyclopedia article read at least enough of the article concerned to determine what it is actually about? --Soundofmusicals (talk) 09:11, 5 April 2016 (UTC)
Wankels have been used in aircraft too, IIRC, so Rotary engine (aircraft) would still be problematic because of that. Other alternatives would be Rotary radial engine or Rotary engine (radial), as they are sometimes called a type of radial engine, but I'm sure those will also bring objections also. I'm not sure there is a better choice of disambiguator that doesn't cause more problems than it solves. - BilCat (talk) 09:59, 5 April 2016 (UTC)
Rotary radial engine is the best of these, and an improvement on the current situation. It's clear, accurate and doesn't lose too much from COMMONNAME. Andy Dingley (talk) 14:24, 5 April 2016 (UTC)
I think Rotary engine (aircraft) has the vast virtue of clarity and it meets COMMONNAME better than anything else which might be concocted. The land-based variants are I think a couple of motorcycles with in-wheel engines (and handling to match) and one or two esoteric racing cars. We can live with those as outliers still under "aircraft", nit-pickingly inaccurate as that might be. We're an encyclopedia, not an ontology. Andy Dingley (talk) 14:14, 5 April 2016 (UTC)
I like Rotary radial engine the best also, but I think that some will object to using radial in the name. To them, radial engine refers only to the fixed type, and the rotary engine isn't fixed. I'd recommend we go ahead and make a formal RM proposal for Rotary radial engine, and post notices on relevant project pages, including MILHIST and WPAIR. We'll see what happens then. - BilCat (talk) 16:16, 5 April 2016 (UTC)
If this is to get serious - I'd like to record a massive great vote for the status quo. Making up a name for something that already has a perfectly good name already is stark daft. Especially as whatever you called it you'd confuse the terminally confused and score the objections of the objectionable. Why not just go the full hog and call it a Twirly Wirly Pop Pop? and change all the WW! aircraft articles to match too? Makes just as much sense. --Soundofmusicals (talk) 21:37, 5 April 2016 (UTC)
I didn't make up the name "rotary radial engine" - see At 1500 ghits, it's clearly not as common, but it's a natural disambiguator. I don't really expect the name to be changed, but the current one's place as the primary topic has always been debatable, which is an indication it isn't the clear primary topic. - BilCat (talk) 23:56, 5 April 2016 (UTC)

Are all rotary engines (in our sense) even of radial layout? other cylinder layouts are (were) very rare, but they do (did) exist, and are mentioned in the article. Look, assuming that this is a serious question (which I doubt) there are three possible "disambiguation" questions that might arise here.

1. Differentiation between Wankel engines (also actually called rotaries) and reciprocating rotary engines.

This remains the only reason that is not totally trivial (why I mention it first). We have discussed this at considerable length in the past, and repeatedly the consensus has come down on the side of the status quo. Wankels do at least have an alternative name, which "our" rotaries do not.

2. Differentiation between a Radial engine (stationary) and a Rotary engine.

Does anyone seriously want to add a qualifier to Radial engine? Because that's the only way to tackle this particular confusion. Either that or get rid of the Rotary engine article altogether, and merge it (perhaps as a discrete section) with Radial engine? Hasten to add that this strikes me as grossly inappropriate too.

3. Differentiation between a (water, wind, steam or gas) turbine and a rotary engine.

This seems pretty far-fetched - but this topic seems to have been spawned by an example of this kind of thing. It stems from ignorance. Turbines are simply not called rotaries. This may be a problem, but it is NOT a disambiguation problem, which is necessarily caused by ambiguity (two things having the same name).

Excuse me if I am taking a sledgehammer to a walnut - but this particular nut does needs to be cracked (preferably smashed) so we can get onto other things. -Soundofmusicals (talk) 01:12, 6 April 2016 (UTC)

Distinction between "rotary" and "radial" engines[edit]

Most people coming "fresh" to this article believe that "rotary engine" means a Wankel and that what we call a "rotary" in this article is a radial. Our initial task here is to explain that no, we are not talking about a Wankel here - and no, in spite of how the picture looks, it is not a radial either. I estimate we actually convince somewhere around 15% or so of readers that this is the case - the rest just shrug their shoulders and say to themselves "Wikipedia is so unreliable!" In view of this we really don't want any tortuous, confusing matter creeping into the lead (lede) - really, we don't. Personally, I have my doubts about that bit about the museum model being in the article at all - with even stronger doubts about it belonging in the lead. If it is not to be moved to a more appropriate place (or simply removed altogether) then it does need to be very carefully worded. --Soundofmusicals (talk) 23:31, 8 November 2016 (UTC)