Talk:Pusher configuration

The SPAD A.2 had a prop mounted inside the fuselage, not in front or behind. Have any other aircraft used this configuration? Drutt (talk) 10:49, 12 June 2008 (UTC)

Not a problems really - the aircraft in question was a plain thoroughly conventional tractor aircraft - except that it had an extra nacelle placed forward of the propeller - strange I know but no problem about which it is! The only other aircraft I can think of with the same arrangement was the B.E.9 --Soundofmusicals (talk) 07:14, 10 July 2008 (UTC)

"pusher" propeller

Basic laws of physics and aerodynamics says propellers are rotating wings and create lift/thrust in the direction of flight. Were a propeller to be mounted "backward", the airplane would fly "that" way. "Pusher" configuration is only a matter of appearance and engineering needs.--Phyllis1753 (talk) 00:17, 10 July 2008 (UTC)

Basic laws of physics (nor, I suspect, aerodynamics) have nothing to do with "push" or "pull". A force is applied in a particular direction (forward or back). Push and pull - in ordinary English (as opposed to scientific and technical language) indicate where the force is coming from - we use the word "push" to indicate a force that comes from behind and "pull" to indicate one that comes from the front. This is, as you very rightly point out, not very scientific - in fact in terms of physics, at least, it is pretty meaningless - but it is the sense in which the word is applied here.

In one sense it is quite true that a "pusher" propeller "pulls" an aircraft just as a tractor one does - but in the same way a "tractor" propeller "pushes" it (in a forward direction of course). --Soundofmusicals (talk) 07:14, 10 July 2008 (UTC)

Was intrigued by your idea that a "pusher" prop "pulls" - although actually on the same grounds a tractor prop "pushes"! The difference is of course really the location of the propeller rather than the nature of the thrust applied to the aircraft. I have tried to keep the sense of what you had to say by leaving your "giving the impression of pushing" - but have cut your sentence that it is "really pulling". The image behind the terminology may well be a bit meaningless (especially in the case of a "push/pull" layout - if that was really what it says the propellers would be thrusting in opposite directions, and would cancel each other out!) - but on the other hand we don't have to get dogmatic about the physics of the situation, I feel. Get back to me if you feel we need to discuss this one. --Soundofmusicals (talk) 23:42, 9 July 2008 (UTC)

(Let's keep this discussion in one place - even move it to the article discussion page? - anyway I have put your reply here)

I've undone your edit. Aerodynamics is aerodynamics; dogmatics is just POV. Props "pull" and there just isn't any other way. I would, in any rate, suggest you bone up on some basic flight theory. Cheers--Phyllis1753 (talk) 00:25, 10 July 2008 (UTC)

Basic laws of physics (and, I suspect, aerodynamics) have nothing to do with "push" or "pull". A force is applied in a particular direction (strictly, "sense") - forward or back. "Push" and "pull" - in ordinary English (as opposed to scientific and technical language) indicate where the force is "coming from" (itself not a very scientific" idea) - we use the word "push" to indicate a force that comes from behind and "pull" to indicate one that comes from the front. You can push a shopping trolley backwards and pull in forwards as well as the other way around, for instance. The difference is where you are standing! This is, as you very rightly point out, not a very scientific use of language - in fact in terms of physics, at least, it is pretty meaningless - but it is the (ordinary language) sense in which the word is applied here. In fact - the propeller is part of the machine itself - it "propells" rather than pushing or pulling!!

In THIS sense it is quite true that a "pusher" propeller "pulls" an aircraft just as a tractor one does - but in the same way a "tractor" propeller "pushes" it (in a forward direction of course). This is nonsense, but it is where you quibble leads us, I'm afraid.

I think my edit - that left the first sentence of your edit intact but removed the essentially nonsensical second one, actually kept what was valid in your argument. I remain open to further persuasion, of course! I haven't reverted it (yet) -until we've had a better chance to make sure we are talking about the same thing!! --Soundofmusicals (talk) 07:14, 10 July 2008 (UTC)

There are times when science seems counter-intuitive and this seems to be one of them. Science says that propellors generate thrust in exactly the same way a wing generates lift regardless of where the prop is located. Popular perception says "props-in-back-must-be-pushing". It's the sort semantics that make the knowledgeable roll their eyes back and think Wikipedia is being overrun by basically ignorant amateurs. Now, I'm no expert in aerodynamics but I have had some flight lessons, I have a aircraft mechanics license and I've been fascinated by aviation for 53 of my 55 years. I know some things, at least, and one of them is that propellors generate thrust in the pressure differential as it moves through the air. It is pulling and the "prop-wash" is the Newtonian opposite reaction. --Phyllis1753 (talk) 14:55, 10 July 2008 (UTC)

It's still called a "pusher configuration" in many noted aviation publications, not "ignorant amateurs", as you should well know. Do you actually have some reliable sources that pointedly state that the term "pusher propellor" is wrong, and why it should not be used? If not, then I don't see why the term can't be used simply as a n expression of how and where the propellors are located. If you have a source that explains why the term is not aerodymaically accurate, not just a statement based on a synthesis of aerodunamic knowlegde. Such info would actaully be useful in the article to explain that propellors don't actually "push" themselves. - BillCJ (talk) 22:24, 10 July 2008 (UTC)

My concern, Bill, is that the article seemed to suggest that the propellor itself generates a "pushing" force. It doesn't. I'm not concerned about the configuration aspect. I use the term myself. As for the theory, look at airfoil, lift (force) and aerodynamic force to begin with.--Phyllis1753 (talk) 22:53, 10 July 2008 (UTC)

The whole point - and I am getting tied of saying this over and over, is that "push" and "pull" are NOT terms in physics. Scientifically, there is of course only "force" (or "thrust"). Of course an aeroplane moves through the air because of the thrust produced by its motive power. (Whether that's an old fashioned prop or a jet exhaust). The word "push" means thrust - the word "pull" also means thrust ... duh!! You can "puch" something forwards, and pull it forwards - you can push it back or pull it back!! I "push" a shopping trolley when I am to the rear of it and applying forward thrust. Nothing to do with amateur or professional, nothing to do with physics or mechanics, that's just what the word means. "Applying thrust from a rear position". Similarly I say that I am "pulling" the trolley if it is behind me! This is not an "ignorant" thing to say at all, it is non technical language suited for a general encyclopedia as opposed to a scientific work. This whole bit is getting very silly - please read my argument and try to understand what I am saying (and what I am NOT saying). --Soundofmusicals (talk) 23:06, 10 July 2008 (UTC)

(Edit conflict) To me, "pusher configuration" and "pusher propellor" are synonymous in usage. So add a good paragraph or two explaining the aerodynamics, and cite it from sources that make that point. Then relax, allow a little leeway, and stop changing every article that says "pusher propellor". What would you think if I started changeing every occurance of "sunrise" or "sunset", stating it's inaccuarate? It is, but it's also an accepted term for the apparant occurance, as is "pusher propellor". This article is the place to explain why it's not quite accurate, but not every article where the phrase is used. There, just link "pusher propellor to this page. - BillCJ (talk) 23:19, 10 July 2008 (UTC)

I think it's because I edited something of soundsofmusicals that started this all off. What I want is some basic scientific integrity about where the pull and push come from. Nothing more. As for changing every article, come on. Just the two about XP-54 and 55 and there I just changed a word or two. Phyllis1753 (talk) 23:30, 10 July 2008 (UTC)

Two, sorry. My apolgies. - BillCJ (talk) 23:48, 10 July 2008 (UTC)

Glad we seem to have resolved this - I could see at once just what Phyllis was getting at - and that it was basically sound - but didn't like the way it was put. A pusher really does "push" - just that this is effectively the same thing as pulling anyway!! I was scared by Bill's comment about other article being changed - had a look and couldn't find any! - But do we need to make a minor adjustment to "tractor configuration"?? Sorry if I was unnecessarily grumpy - it was late, and I am elderly. --Soundofmusicals (talk) 15:14, 12 July 2008 (UTC)

Just a quick note on this discussion. Could we not easily differentiate the two type by saying that in one case, less say a normal configuration the main part of the airplane has a force applied to it due to the tension in the propeller shaft, where as in a pusher the aircraft has a force exerted on it by compression in the propeller shaft? --Plaugepony (talk)

Moved your comment to its proper place at the bottom of the page! All else confusion as we don't know where we are. You are probably right - although personally I think this whole bit was silly in the first place and as far as I am concerned is long resolved - by all means edit the article arcordingly if you want, but keep it simple and non-technical please. --Soundofmusicals (talk) 19:10, 9 January 2009 (UTC)

citations needed

The article has an infobox at the top declaring that there are no sources for this article, and that references are needed. While citations are indeed absent from the entire article, the "disadvantages" section has "citation needed" after practically every sentence. Is this necessary? Doesn't the infobox at the top cover the fact that citations are needed for the whole article? Conversely, if citations are needed for that section, why doesn't the "citation needed" annotation appear after every sentence in the entire article, including the "advantages" section? The way the article presents currently makes it seem like the assertions in the "disadvantages" section are somehow less legitimate than the rest of the article. AdamBellaire (talk) 15:59, 4 April 2009 (UTC)

Someone obviously didn't like the idea that pusher props have disadvantages and stuck in a great rash of random tags - these admittedly serve no useful purpose and should be deleted but we're not supposed to do that. What is actually needed is for someone to get together a few good sources and add valid citations (for the whole article - not just the "attacked" section).--Soundofmusicals (talk) 19:11, 7 April 2009 (UTC)

I just took a look at those fact tags .. seems some are quite justified. Look at this one:

As a result, pusher aircraft such as the canard homebuilts are not usually operated from unimproved runways[citation needed].

Almost all flexwing aircraftare pushers .. and they are more often than not operated from 'unimproved runways'. Grass strips, often. So the statement in the article is at best 'misleading'. quota (talk) 20:15, 7 April 2009 (UTC)

Not saying for a moment that ALL tags are necessarilly unjustified at all! Just that what we need is something constructive rather than a set pf tags that obviously target every second sentence or so at random! On the whole that set of tags constitute vandalism, to be honest - even if several of them turn out to be justified! (So many of them - the probability is that some are - that doesn't mean any of them were inserted for a rational reason!). My main point (in answer to AdamBellaire) is that the whole article does need checking with good sources. --Soundofmusicals (talk) 00:27, 8 April 2009 (UTC)

We are in complete agreement :-). I'll take a look and see if any can be obviously pred out .. or reduce to a general comment ... I think I've seen a suitable template somewhere. quota (talk) 07:42, 10 April 2009 (UTC)

OK, done, cleaned it up a bit (but it still needs refs). quota (talk) 08:01, 10 April 2009 (UTC)

Most recent edits

Most of these were good - but I've re-instated information in the "definition" at the top of the page that had become unclear. I think getting back into a debate about whether a pusher prop really "faces the rear" or "pushes" the aircraft is liable to decend to one of semantics and be most unhelpful. This is not an engineering text - and our definition needs to enlighten rather than mystify an ordinary user who just wants to know what a "pusher" aircraft is.--Soundofmusicals (talk) 23:06, 18 February 2010 (UTC)

Interrupter vs synchronisation

The gear that enabled bullets to pass between the blades of a spinning propeller was strictly a "synchronisation" gear - although it is more usually called an "interrupter" gear. The article on the subject (rightly, I think) calls it an interrupter gear - although it does explain why this is strictly speaking incorrect. In either case very marginally notable in this article, the subject of which specifically didn't need any such thing!! --Soundofmusicals (talk) 05:30, 15 October 2010 (UTC)

Let me get this straight. Calling it interrupter gear is wrong, you acknowledge that fact. Yet you changed it from sychro back to interrupter.

Sychro gear and interrupter gear are 2 completely different things, they just have similar effects. Much like saying a motorbike is a car because they both transport people.

Why wold you go out of your way to make an article wrong?

Doktordoris (talk) 21:30, 21 October 2010 (UTC)

No and I didn't. Read my post please and respond to point made rather than repeat yourself. Many things have strictly incorrect names. The name "Pusher configuration" has even been questioned because the propeller does not literally "push". If everybody called motorbikes cars then that's the term we would use. This is actually a highly trivial matter HERE - we are not saying anything other than the very obvious fact that pusher props never required interrupting/synchronisation. If you want to change the term used for the article on synchronisation gears that would be another matter altogether - by no means sure I wouldn't agree with you in that case. Until then, "Interrupter" - even if its strictly wrong, remains the main entry for the topic, and this highly peripheral mention of it is not the place to change this. --Soundofmusicals (talk) 01:05, 22 October 2010 (UTC)

It's obviously not that 'trivial' to you as you have changed it twice, is it now? Fokker never made interrupter gear, in fact no-one ever made interrupter gear. However I'll leave it as it is, I wouldn't want to upset you with my desire for accuracy.

Doktordoris (talk) 13:15, 22 October 2010 (UTC)

Glad you saw the need to edit out personal stuff from earlier drafts of the above answer - I'll follow your example and keep this as impersonal as I can. We are agreed that "interrupter gear" in this context is less technically correct than "synchronisation gear", or at least that it does not describe quite so well what actually happens when such a gear operates. The main article for the subject actually makes this clear, and explains why. The article is none the less called "Interrupter gear", probably (although I have not seen this argued) on the grounds that it is the more common term (as I think it probably is, if marginally). In any case if we are going to decide to call "interrupter gears" (in this sense) "synchronisation gears" we should start, I think, by renaming or otherwise editing the main article (this one) rather than one that mentions the subject at all only in passing, and in a negative sense. In the meantime consistency (calling the same thing by the same name, at least) takes priority here. In particular, we link to another topic by its own name rather than through a redirect, where practicable. --Soundofmusicals (talk) 15:17, 23 October 2010 (UTC)

Pusher definition

"...a pusher configuration has the engine(s) mounted forward of "rearward-facing" propeller(s), so that the airframe is propelled by force applied in compression from the rear rather than in tension from the front."

First we have to specify that a pusher is a propeller driven airplane (not a jet).
According to Phyllis1753 and Soundofmusicals :

1. a propeller apply a forward force, neither push nor pull,

2. the tractor/pusher difference is of course really the location of the propeller.

1.Definition proposal:

"A pusher configuration definites a propeller driven aircraft with the propeller(s) mounted behind the engine(s), at the back of the airframe".Plxd (talk) 09:21, 13 October 2011 (UTC)

"At the back of the airframe" won't do at all - many pushers have had their propellers installed about halfway between the front and rear of the airframe. This is especially true of multi engined pusher (and push/pull) types with wing mounted engines, as well as "tail boom" types. The point is NOT the "location" of the propeller at all - but the direction (in physics, the "sense") that it faces.

The idea that it is likely anyone would confuse a pusher aeroplane with a jet is in any case increditably remote - but is also countered in the first sentence already.

"Push" and "pull" are not actually terms in physics - hence the rather obscure phrase about "force applied in compression from the rear rather than in tension from the front". Push and pull are perfectly good words in ordinary English - but some editors were adamant that this wasn't good enough, which is why we ended up with this one. "Pushing" and "pulling" forces do in fact act differently on moving bodies that are subject to other forces like drag, weight and lift, at least if the body is "accelerating" (in the sense used in physics - changing its speed and/or its direction). All the forces acting on an aeroplane are "vectors" - that is they have more than one quality, in this case quantity and direction. In different circumstances they balance each other in different ways - which is the thing that makes control of an aircraft possible, of course. So no - it is NOT a case of "neither push or pull".

Finally - the first sentence of your proposed definition isn't really in English, is it - it would need rewriting to be usable. Like, is "definite" a verb?

I do think, however, that we can do better with our opening, defining sentence. (see attempt to do so)--Soundofmusicals (talk) 10:42, 13 October 2011 (UTC)

Oh, and I've cut the bit about canard surfaces. For a start this doesn't fit into the sentence in any meaningful way - then it is out of context, in that we are discussing propeller position (no direct bearing on canard surfaces at all). Finally it is not by any means part of the definition - not all pushers have canard surfaces (although some have had them, and from the very begining(!) - and by no means all aircraft with canard surfaces have been pushers!! --Soundofmusicals (talk) 11:01, 13 October 2011 (UTC)

As the title of article is "Pusher configuration", it seems that the title has to be repeated in the definition. Sorry for my poor english; not 'definites' but 'defines'. Because it is a matter of propeller location, it seems more logical to start the definition with the propeller, and then the engine. "at the back" is not correct, sure; I tried to talk about towards back (I have not the words). Maybe the final part of the definition (so that the airframe is propelled by force applied etc...) is usefulness, 'propeller driven' may suffice.

2.Definition proposal:

"A pusher configuration is (or defines) a propeller driven aircraft with rearward-facing propeller(s) mounted behind the engine(s)".Plxd (talk) 12:27, 13 October 2011 (UTC)

I've added Horatio Barber's definition from his book - essentially that the prop is behind the main lifting surface - and it does apply to all the aircraft in the gallery and most pushers I can recall. GraemeLeggett (talk) 19:12, 13 October 2011 (UTC)

Sorry Plxd, but this is a clear case where simple, direct English is better than convoluted statements about configurations defining things. Better to just say straight out what a pusher is. Graeme - I like the Barber definition, and it is NEARLY foolproof. Thinking of some pusher biplane flying boats with engines (and props) mounted on top of the top wing or between the top and bottom wing - and your typical late thirties French four-engined bomber with its underslung push/pull arrangement, again under the wing rather than behind it - I think that "behind the leading edge of the main lifting surface(s)" would have been just a little more accurate - but then we don't fiddle with direct quotations, and I don't think it is worth the confusion it might cause to add a qualifying sentence. I have separated the Barber bit and put it at the end of the lead - it is an observation rather than a definition, as we have attempted it. In any case better to let our "authority" have the last word. --Soundofmusicals (talk) 23:21, 13 October 2011 (UTC)

I wonder if a there's a later definition that relates the prop position (thrust) along the longitudinal axis relative to the centre of pressure (or (aerodynamic center]]?) which would be level with somewhere in the middle of a monoplane wing. Push-pull, while mentioned here, is not really a case of pusher configuration - more a question of getting enough power in a small enough frontal area and/or putting engines far outboard (IMHO). A foray into the Flightglobal archive may turn up more. GraemeLeggett (talk) 05:39, 14 October 2011 (UTC)

Addendum - a foray showed that the phrase pusher doesn't appear in Flight until 1913, "tractor" appears from the first year (1909) a quirk of the OCR? GraemeLeggett (talk) 10:34, 16 October 2011 (UTC)

3. Definition proposal, Barber definition, Soundofmusicals modified:

"an aeroplane of which the propeller is mounted behind the leading edge of the main lifting surface".

Some examples : Poschel P300 Equator, Radab Windex motor glider, Seawind 300C seaplane, A-90 Orlyonok amphibian, e-Genius GFC competitor. In 1980, there was a german glider Calif A 21 fitted with a forward-mounted ducted fan located on the wing (behind the LE). Tractors or pushers ? Maybe the engine/propeller relative position is more significant than the propeller/main wing relative position.

Conversely there is a recent example of a push-pull aircraft with engines pods ahead of the wing. Cri-Cri, four electric engines. http://www.enerzine.com/1036/10285+le-quadrimoteur-electrique-cri-cri-sest-envole+.html

A remark about the present definition. "rearward-facing" propeller(s)". As a propeller blade has two faces, it is both front and rearward facing. Better to say that the prop is behind the engine or backward mounted.

The (4-electric version) Cri-Cri engines could be seen as pulling the rest of the aircraft through the air, which would make it a tractor. Nothing in the article on it mentions "pusher".GraemeLeggett (talk) 08:36, 15 October 2011 (UTC)

It's technically a push-pull of course since the props face in opposite directions - but I agree with Graeme that the total effect is really that of a tractor. I think this confirms that the Barber "definition" misses something - but then how could he (or anyone) have predicted such an unlikely prop arrangement as that? --Soundofmusicals (talk) 13:44, 15 October 2011 (UTC)

4. Definition proposal took from WP Push-pull configuration definition :

An aircraft constructed with a pusher configuration has backward-mounted propellers.Plxd (talk) 12:49, 14 October 2011 (UTC)

I think, honestly, that the definition is about right - the propeller is very specifically not "backward mounted" - get a model aeroplane prop and try turning it round and you'll see what I mean. You actually need an opposite-handed prop - or a motor that turns the other way - before it will "push". If you just turn the prop round the plane will try to fly backwards! A pusher propeller as a whole "faces" towards the rear - don't go complicating this - remember the object of a definition here is to put it in a way that explains it clearly to a person who might not know what a pusher is, rather than satisfying all the quibbles of an aeronautical engineer - who already knows very well what a pusher is and doesn't need our definition anyway. Frankly I'm not sure exactly what you mean about the blades of the prop facing in different directions anyway - if that were the case the two blades would cancel each other out, wouldn't they? Or have we got yet another problem with English? --Soundofmusicals (talk) 08:22, 15 October 2011 (UTC)

A propeller blade has two faces, the forward face (blade extrados) and the backward face (blade intrados). It is not question of opposite-handed prop or sense of rotation here. If I understand correctly your remark, backward means reversed (prop). I understand that "rearward facing" means in fact you can approach more easily the propeller by the back, because of the engine (or wing or fuselage).

5. Definition by Jan Roskam in Aiplane Design, Volume 2, page 132

"As a general rule, when the propeller or inlet plane is forward of the c.g., the installation is referred to as a tractor installation. When the propeller or inlet plane is located behind the c.g. the installation is referred to as a pusher installation".
If I understand, Jan Roskam considers jet engines too. So my previous definition with "propeller driven", or better : "commonly reffered to as propeller driven".

This definition reads as a more precise definition of Barber's statement. Given the years and difference in target audiences between the two, I'd say they are close. When there is but a single mainplane (mainplanes for biplane) the CofG is somewhere between the leading and trailing edges (or somewhere along the Mean aerodynamic chord for a swept/tapering wing. Between the Prof and Barber we have a definition and a bit of history of the definition. The definition is also independent of where the engine is situated or how the power reaches the prop. As an acknowledged authority and therefore RS, we can use this definition without further ado. Though I would like to see another source confirms the same approach is taken with jets, and by extension the Sud Avation Caravelle can be described with the phrase "pusher aircraft" or the Boeing 737 Classic as a "tractor" (aside from the Lun ekranoplan I couldn't find a nose mounted jet. GraemeLeggett (talk) 10:17, 16 October 2011 (UTC)

Pusher means pusher prop. All else confusion. If you wanted to extend the pusher/tractor dichotomy to jets then all jets are pushers, plain and simple - but I think this is bordering on the plain silly. --Soundofmusicals (talk) 12:13, 16 October 2011 (UTC)

Pending a consensus, I have changed the intro as what was there was nonsense. I am sure someone can do better, but rather than have all kinds of great definitions here, and a hopeless one on the actual page, I have changed the actual page - even if it is on an interim basis only.NiD.29 (talk) 01:13, 17 October 2011 (UTC)

Pushr configuration is todo with the relative position of aircraft and propeller. If you look at (eg) a typical Bristol Boxkte Gnome installation, the propeller is in fact mounte in front of the engine. Similarly there are Gnome installatins on some examples of Bleriot tractor monoplanes where the engine is in front of the prop.TheLongTone (talk) 13:16, 28 October 2011 (UTC)

Push-Pull

GraemeLeggett says : "Push-pull, while mentioned here, is not really a case of pusher configuration". When the push engine is located like true pushers (twin boomers for example), we can consider it is quite a pusher, because the aircraft has the same layout as true pushers. When the push engine is just added to a conventional layout (push-pull inside the wings or above the wing for example), I agree that it is questionable. Maybe we have to focus on specific pusher configurations. Plxd (talk) 12:49, 14 October 2011 (UTC)

A "push-pull" is BOTH a tractor and a pusher at the same time, if you like. We do indeed "focus" on aircraft that are specifically pushers here - but push-pulls do need a mention, probably about as much as they already get? --Soundofmusicals (talk) 08:27, 15 October 2011 (UTC)

Recent rewrite of history section

To SoundOfMusicals I say, "Well done".

There's possibly something to be added about a rear positioned propeller being advantageous for certain circumstances. There's the Miles M.35 (where the choice was about pilot view in decklanding) and there were a number of British wartime designs for ground attack aircraft that were not taken up (where it was a view to protecting the engine). However until I can check Buttler to see if he generalizes on the subject, or another source holds an opinion, I don't think they could be added (yet).GraemeLeggett (talk) 12:27, 13 October 2011 (UTC)

New "history" section

This was VERY bad really - which was showing up more and more as the rest of the article was improved. It is still far from perfect - in particular it needs at least a few citations (find them please - rather than peppering in tags) and examples. On the other hand I think it now makes a good deal more sense overall than it did. --Soundofmusicals (talk) 12:29, 13 October 2011 (UTC)

Thanks for the kind remarks Graeme - I obviously put in the above before I read them! --Soundofmusicals (talk) 12:31, 13 October 2011 (UTC)

About the sentence: "Well before the beginning of the First World War it was apparent that etc...", it seems it is a bit complicated and incomplete. The aft framework was surely draggy, but the open cockpit, braced wings and gear drag (common to tractors and pushers) was very high too. The pusher propeller efficiency was certainly very low, the worst possible, IMO the first cause to the tractor superiority.Plxd (talk) 09:20, 14 October 2011 (UTC)

But the tail, with all its extra bits and pieces and wires and whatnot was EXTRA drag. Actually there was relatively little if any difference in prop efficiency as such. --Soundofmusicals (talk) 08:08, 15 October 2011 (UTC)

Just a drag estimation. Say a pusher aircraft with about 30-40 % of induced drag (like any "slow" aircraft); remaind 70-60 % of parasitic drag. Tail framework drag may be about 10 % of that, that is 6-7 % of the total drag. Pusher propeller efficiency drop is certainly more than 10 %; a drop of 15 % is probable (about 12 % for a clean VariEze, likely more for a 1914 biplane). The propeller may count 2 times the tail.Plxd (talk) 17:07, 15 October 2011 (UTC)

Tail framework drag only 7% of total drag !?! have a close look at a typical 1913-1915 pusher for a moment! I'm sure that is a VERY optimistic estimate - much more likely to be something between 15% and 25% (most of the rest being the drag of the wing structure of course). Prop efficiency drop is not necessarily more for a high drag airframe than for a modern "clean" one - it would probably be either about the same or rather less, due to the much more slowly revolving prop (about 1500 rpm). A useful guide may be that a "replica" pusher with a modern engine needs to develop about twice the horse power of the original powerplant to achieve a similar performance. --Soundofmusicals (talk) 05:01, 16 October 2011 (UTC)

Following your estimate, the tail framework drag (the framework only, not the tail surfaces) counts 20 % of the total drag, that means 29 to 33 % of the total parasitic drag (wings, tail, open fuselage, gear, engine, tanks, armament), not forgetting the induced drag being 30 or 40 % of the total drag. If we consider that the framework count 20 % ot the parasitic drag, we get about 12-15 % of total drag : about the same value that the push prop efficiency drop. So I keep my previous remark. Your last sentence explains the deciding effect of the prop loss of efficiency.Plxd (talk) 09:45, 16 October 2011 (UTC)

I think its fairly clear that the difference in prop efficiency between a tractor and pusher installation may well have been less than it would be for a modern aircraft - certainly it is unlikely to have been more. A reasonably clean (by the standards of 1915/16) tractor fuselage has very obviously a great deal less drag than the "nacelle and booms" equivalent of even a well designed c1915 "Farman type" pusher. Any speculation about the extent to which other factors also had a bearing on the case is likely to be pretty barren - essentially it remains speculation, unless someone has done a specific study comparing the horsepower required to get various tractor and pusher replicas of types of the period to perform at a similar level to the originals. The nearest thing to this would be the collection of c1910 replicas and originals assembled for the movie Those Magnificent Men in their Flying Machines, but there really isn't a lot you could extrapolate from this experience that would be directly relevant to our case. As I remember they actually had just the one pusher, a Bristol Boxkite, which needed a much more substantial increase in power over the original 1910 engines (over 100%) than their tractors did. How much that actually proves I wouldn't like to guess, but insofar as it means anything at all it seems to indicate that the prop on the original boxkite was a good deal more efficient relative to its higher revving modern equivalent, while the props on the (much cleaner) tractor types, while still more efficient than the modern ones, generally required less drastic increases in brake horsepower. --Soundofmusicals (talk) 12:05, 16 October 2011 (UTC)

Special advantage

"The propeller of a single-engined airplane can be placed closer to the elevators and rudder. This increases the speed of the air flowing over the control surfaces, improving pitch and yaw control at low speed, particularly during takeoff when the engine is at full power."

1. Aerodynamics. Anyway the prop is close to the tail or remote (at the front like tractors), the tail is commonly within the prop slipstream.

2. Statistics. Highly manoeuverable propeller driven aircraft (aerobatics) are tractors and not pushers.

3. Physics. A propeller has a lot of gyroscopic effect, that is an inertial effect that opposes to movement. The more the tail is remote from the prop, the more the tail is able to move freely.

This "advantage" is free from any since 2006.Plxd (talk) 10:30, 16 October 2011 (UTC)

Personally - I wonder if the "advantages/disadvantages" section doesn't actually need a good clean out - with only absolutely obvious and indisputable ones left in. Too much speculation altogether, and anecdotal evidence doesn't prove very much either. The one you detail above would be an obvious one to go. The ones we leave in might be qualified at times by pointing out more unambiguously that the particular advantage/disadvantage applied to a particular historical period, or at least applied more strongly then. Incidentally - since pushers have been such a tiny minority of all propeller driven aircraft since 1915 any "statistical" alalysis is completely meaningless. So all acrobatic planes are tractors? so are practically all propeller planes! Historically, there have been some very manoeverable pushers. --Soundofmusicals (talk) 12:35, 16 October 2011 (UTC)

The fact that there are neither prototypes nor built pusher prop aerobatic aircraft implies there are no "statistics", yes, but well known technical reasons explain why there are no pushers; this is not "meaningless". Plxd

Perhaps if the section was more general and just noted the physical effects/consequences of putting the prop at the back/near the tail/behind the wing and so on and let the reader develop their own ideas - every single aircraft design is an engineering solution to a set of problems.

That definition!!

The lead of an article like this needs to be a definition of its subject - in fact I think this is all that should be there - remarks peripheral to the actual definition are better set out below.

To summarise what I think would probably be consensus (or at least things we COULD agree on, if we haven't already)

1. PLEASE, we are talking about a propeller (note spelling - NOT "propellor") configuration!! Jets don't have propellers (except for prop jets of course) - two parts they do have LIKE a propeller are the compressor or fan (ALWAYS pointing forwards) and the turbine (ALWAYS facing the rear), so the whole thing, if applied to a jet aircraft, is plain silly nonsense.

A jet has a lot of internal propellers, compressor and turbine stages, each one with both front and back facing blades. Comparing with a propeller+engine group, it is a push-pull engine. This article is obviously about propeller driven aircraft; Jan Roskam definition asks for telling it. Plxd

2. The main (only?) defining point is that a "Pusher" prop pushes. Some people don't like this (although some of the reasons they give are far from valid) but it remains true of course that a propeller in itself produces forward thrust, whether it is mounted as a pusher or a tractor. (I was going to say "simple" forward thrust, but of course the forces produced by a propeller are far from "simple"!!!) Anyway, hence commeth our rather strange contention that "the airframe is propelled by force applied in compression from the rear rather than in tension from the front". This may LOOK "muddled" or "garbled" or be considered incomprehensible - but it can't just be deleted - it is what was left after consensus of the time said we couldn't use the word "push" (at least out of "scare quotes").

"Simple, direct English is better", ok. Plxd

3. We have had a bit of quibble about the idea that a propeller can "face" in a direction. This is, with all due respect to the fine people who feel troubled about this, a fairly sensible, ordinary English as opposed to technicalese, way of saying that a pusher prop, well... faces backwards.

So "rearward-facing" propeller(s) seems ok ? plxd

4. We then describe (very briefly) the way a pusher prop is typically mounted to an aeroplane - the way this has been worded probably IS a little muddled and garbled - due to "multiple person editing" over a period of time. Having reverted a good faith but (I thought) unsatisfactory replacement for this I am about to have another swing at it. Incidentally I would like to wipe the "pusher configurations" section altogether! (But that is another question).--Soundofmusicals (talk) 04:54, 17 October 2011 (UTC)

The Pusher configurations section may be simplified, and then List of pusher configuration becomes enterily usefull.Plxd (talk) 13:49, 17 October 2011 (UTC)

The wording isn't just muddled - the author(s) apparantly knows little of how one works since there is no compression/tension difference. The ONLY difference is that the engine is ahead of the propellor, vs. behind it. The only change to the propellor is that it may need to be handed the opposite direction (unless the engine rotates the opposite direction to the one used as a tractor). Finally the thrust bearings on the engine are different in a pusher installation since the propellor/er is pushing into the engine into rather than away from the engine (which in turn can make a pusher installation more expensive). The version in place now is much better.

Since c of g considerations pretty much determine where the engine is placed, this tends to put the propellor behind the c of g but it is not a requirement in itself. Indeed the Caproni Ca.60 (push-pull triple triplane) has pushers on the forward wing, well ahead of the c of g. (not that it flew well but that is another story - and it did get into the air) and if you were to flip the engines around on a cri-cri, you could have a pusher, with the propeller ahead of the c of g, and wing. Not that you would of course, but I am sure someone has tried at some point. I am not sure the quote is the best one since he made it at the very dawn of aviation, before a lot of possibilies had been tried out. Most pushers now are seaplanes, and they do not fit his definition.

I didn't like the pusher configurations section either - formatting is poor and I know there are other possibilities - such as geared/belt driven out to the trailing edge of the wings (I just can't find an example, and I know I have seen one - perhaps only as a project but still...) ps: propellor is indeed a legitimate alternative spelling for propeller (though I should have kept consistant with the rest of the page) NiD.29 (talk) 17:27, 17 October 2011 (UTC)

Ultimately the definition comes from the reliable source, so I added Roskam as well to the lead. GraemeLeggett (talk) 18:38, 17 October 2011 (UTC)

It isn't a reliable source though - 90% of aviation development was yet to come, and was thus a closed book to him, and he was familiar with only one very specific arrangement.

According to The Cambridge Aerospace Dictionary by Bill Gunston OBE FRAeS (Fellow of the Royal Aeronatical Society) and Editor of Jane's Information Group, Cambridge University Press Cambridge, UK, 2004, ISBN-13 978-0-521-84140-5/ISBN-10 0-521-84140-2 " pusher aircraft One with pusher propellor(s) only pusher propeller One mounted behind engine so that drive shaft is in compression " Absolutely nothing about c of g, location in relation to wing or any other nonsense - and with 730 pages of definitions I doubt they needed to skimp. A pusher is quite simply an aircraft designed so that the engine is ahead of the propeller regardless of where the engine or propeller is located. The propeller imparts its force forward, into the engine rather than attempting to pull itself away from the engine. The very fact that "some variations in pusher aircraft design[note 1] since have produced exceptions." has to be added should be a clue that the rest is nothing more than a misconception (though none of the aircraft listed in the note are pushers by anybody's definition).NiD.29 (talk) 04:23, 18 October 2011 (UTC)

I was not referring to a specific definition when talking about reliable sources - I was saying that we needed to use them rather than come up with our own, and as Roskam is a more recent source I added him to the lead. And now we have another one to add. Though just as we may find holes in Barber and Roskam, The Aerospace Dictionary does not cover the instance of a drive belt to transmit power as in the Wright flyer. I think what we are finding is that the definition is multi-faceted. GraemeLeggett (talk) 05:25, 18 October 2011 (UTC)

Graeme, I agree totally about "muti-facetted" definitions - or at least matter that is truly defining, and other matter that is perhaps not actually defining at all - but none the less generally quite true, and USEFUL. The following paras were written while you were writing your (like, an edit conflict) but I think we are actually on the same track.

I like the bit about "The propeller imparts its force forward, into the engine rather than attempting to pull itself away from the engine" - and that information about different ballraces based on this. In fact I'd like to see that worked into the first paragraph of the article. The old bit about compression and tension always struck me as very likely - it went because it was howled down as "nonsense", and I couldn't see it ws actually necessary. I honestly think a pusher prop DOES "push" in a way, even if we have to qualify that a bit to keep the technical people happy. I left in (I did NOT add) the bits about the position of the propeller related to the wing/c.g. NOT because I particularly like them as definitions, but because they seem to be generally accurate observations. And, on the whole, helpful to someone who just wants to know what a pusher actually is.

This is a GENERAL encyclopedia - while we are going into much more detail, and endeavoring to achieve much more accuracy than your typical general encyclopedia might - this is still not a technical engineering treatrise, or I couldn't work on it , and neither, I suspect could you or the others. The definition as it stands (assuming someone is not hacking at it while I speak) currently gives what I think is the right definition, really, (even if it is either two long-winded or too sketchy) followed by an alternative that is at least interesting, not to mention largely true (although perhaps not "defining"??)

The "two definitions" go together and are not necessarily contradictory - in fact either one seems to imply the other? --Soundofmusicals (talk) 05:50, 18 October 2011 (UTC)

I think there was too much emphasis on the location - sort of confusing the symptom with the disease - the c of g thing might usually be true, but it is not essential - it is instead a symptom of the need to find a way to balance a very heavy engine in a way that doesn't mess up the aircraft's flying characteristics completely. The relationship between the engine and propeller is the essential part.

Aside from the thrust bearing issue, if the engine is mounted above the fuselage, it must be inclined to the "normal" thrust line otherwise it will not be able to leave the groun, which further reduces its efficiency since it always operates at a much greater angle to the airflow than a conventionally mounted engine. This p factor, combined with a tail that is ineffective with no propwash going past it (a conditon it experiences at high angles of attack, and while landing, taking off or taxiing), makes the arrangement dangerous to spin. I conjectured that if my father ever entered a spin with his Volmer Sportsman, adjusting the power might be the only escape. Due to the various control problems I did extensive research for solutions - alas he won't buy new thrust bearings and that leaves only major surgery.

Also - it was one of the quietest powered aircraft I have flown as the exhaust and propeller are masked by the fuselage, and well behind you, rather than in in your face. If you are standing behind it when it runs up, that is a whole different story but even when it is in the air the fuselage and wings block much of the noise.

ps: I have taught aviation theory so I suspect I know a thing or two, and I have a whole tassle of books on aeronautical engineering, aerodynamics, etc to fall back on for clarification. A personal favourite is "The Aerodynamics of the Unconventional Air Vehicles of A. Lippisch" by Henry Borst though it isn't much help here as it is more theory than definition. The research papers of the Royal Aeronautical Society are more enlightening regarding the simple stuff but I don't have my own copies (and the ones I can get access to stop just when everything starts to get really interesting).NiD.29 (talk) 06:37, 18 October 2011 (UTC)

Yet another "new try"

I have now rewritten everything down to the "configurations" section - a great deal of what follows I really want to trim (much of it to the point of deletion) - I would appreciate feedback, obviously, before doing anything so drastic, as well as comments on the article "as rewritten". --Soundofmusicals (talk) 08:06, 17 October 2011 (UTC)

Thanks to Plxd for your work on this - although I disagreed with some of your changes I have left the most important - moving the paragraph describing the standard Farman layout to the "history" section. This produces problems (like the disociation from Barber) but on the whole it does work rather better. Any ideas about what should (or shouldn't) get edited or deleted in the lower part of the article?? --Soundofmusicals (talk) 11:50, 17 October 2011 (UTC)

My changes were for an easier reading (Farman text group), and chronological (Pénoud, French/English pushers, homebuilt before UAV at the end of history). I moved the technical remark to notes level in order to simplify the introduction text for the current WP reader : shorter text, without (text inside) or "although" etc.... I added bullets, I know one do not like that, but IMO it is necessary whithin a long section, again to ease the reading. Another advantage, this constrains to look for a tittle giving the essential sense of the text, and to search and group some infos which are scattered.
About "Avantages/disadvantages" section, I agree with your remark : too much detailed. There are too numerous and different aircraft, each one with special characteristics, so trying to write a simple WP sources reliable pros/cons may be hopeless or too complicated, anyway too long. "Too long" was the reason to create the (disputed>to be deleted) List of. I started to modify and complete this section because of too many incorrect or even false content (never tagged, too); for example some (frequent) affirmations as "better efficiency because of boundary layer etc..." or the visibility/no interference with prop or engine was not placed in first rank of advantages. Thanks for your re-writing; this article was quasi-sleeping. Plxd (talk) 13:49, 17 October 2011 (UTC)

The "Farman" layout was very simply the way that "true" or "classical" pushers were laid out from around 1910 - when the forward elevator (an all-flying canard) started to go - right up till The first serious experiments with alternative pusher "formats" began in the late thirties early forties. Remarks about a proper description of how a "Farman pusher" was laid out being "irrelevant" are frankly highly bizarre. If you think otherwise - at least bring up your arguments here! --Soundofmusicals (talk) 03:36, 18 October 2011 (UTC)

Rationale for wording about the B-36

The original wording of this had holes in it that needed to be forestalled - among other reasons because someone with a technical mind is going to come back at us. In other words we need to get things right!

1. Was the B-36 a pusher at all? It certainly uses pusher propellers - but then so do "push-pull" types, which are not really true pushers (or if they are, they are also tractors!). Having the props so close to their usual place in a multi-engined aircraft - i.e. on the wing - just behind it instead of in front of it - means that MANY (not all of course) of the generalisations we can make about pushers don't apply. You can in fact argue either way, of course - but there are people who would argue that the B-36 is NOT really a pusher. The "at least using pusher propellers" bit covers this.

2. Fixed-wing aircraft here is Wikipedia "house style" way of saying "aeroplane/airplane" - have a look at the article. we are not contrasting the B-36 with rotary wing aircraft (none of which are anything like as big of course) but with airships - several of which have at least approached, if not exceeeded the size of the B-36. Airships also have pusher propellers (!!) although of course no one claims there are "pushers" in the sense used in this article.

Hope this is now clear - before you jump into edit war mode, please do raise problems you have in discussion - makes life much easier. This was (and still is in places) a very bad article, and one or two of us are trying VERY hard to make it a better one. give us a bloody chance, please. --Soundofmusicals (talk) 03:54, 18 October 2011 (UTC)

I agree it is a very bad article, but harsh as it is (and I would rather not be) I see none of your edits actually improving anything. You might just want to stick to subjects that you have some knowledge of or can at least access good references.

1. Maybe you should visit the Convair B-36 page. The early versions had only piston engines, and all are mounted in a manner that every oddball definition you have come up with here would include as a pusher. Yes - the props are behind the c of g, and are behind the engines, and the engines are even behind the c of g. The later addition of jet engines does not negate that it was a pusher - it was designed, built and flew without them. On the other hand of the four aircraft you listed in your note in the intro as exceptions to the rule - NONE are pushers.

2. Largest "airplane" eliminates airships as they do not rely on wings (ie planes) for flight and are therefore not airplanes although they are aircraft - "fixed wing" is a seriously awkward way of putting it and it reduces readability. Wikilinking allows you to make links without using the name of the page in the text being linked from.

From "The Cambridge Aerospace Dictionary" (2004) which has impeccable credentials - it was written by Bill Gunston, one of the foremost aviations writers in the world today, recipient of the OBE for his "services to aviation journalism", and a Fellow of the Royal Aeronautical Society says:

(quote)

• Aeroplane (US = airplane) BS.185, 1940: 'A flying machine with plane(s) fixed in flight'. Modern definition might be 'mechanically propelled aerodyne sustained by wings which, in any one flight regime, remain fixed'. Explicitly excludes gliders and rotorplanes, but could include MPAs, VTOLs and convertiplanes that behave as * in translational flight

...

• Aircraft Device designed to sustain itself in atmosphere above the Earth's surface, to which it may be attached by tether that offers no support. Two fundimental classes are aerodynes and aerostats

...

• Aerodyne Heavier-than-air craft, sustained in atmosphere by self generated aerodynamic force, possibly including direct engine thrust, rather than natural buoyancy. Two major categories are aeroplanes (US=airplanes) and rotorplanes, latter including helicopters

...

• Aerostat Lighter-than-air craft, buoyant in atmosphere at a height at which it displaces its own mass of air. Major sub-groups are ballons and airships. In airships aerodynamic lift from hull can be significant, but not enough to invalidate classification under this heading

...

• pusher aircraft One with pusher propellor(s) only
• pusher propeller One mounted behind engine so that drive shaft is in compression

(end quote)

I hope this clears up the confusion because I would like to be able to point to articles on aviation subjects like this and not get laughed at when I say wikipedia can be a useful reference. My apologies if I have offended you with my bluntness, it was not my intent. NiD.29 (talk) 05:19, 18 October 2011 (UTC)

1. I do have a background in aviation history, going back more years (I hope, for your sake) than you. I do have access to a great many very good sources (I am sitting in a fair sized room where they line the walls (known to my younger relatives as "Grandad's aeroplane room"). I know all about the names for different types of aircraft. I am very far from being a congenital moron.

2. Of course you meant to offend - why the hell else carry on like that? What other purpose might you have had? The important thing is that you have not offended me in the least, just given me a good old belly laugh. I was feeling a little low - much rather be in the garden than here - I am very elderly and am suffering from a debilitating heart condition - so thanks for the lift.

3. The point is that we have a "house" use of terms problem in Wiki. Each article is not a stand-alone magazine article and "house style" is important. There are administrators and other pains in the (naughty word expunged) who have been known to edit and tag and refuse 'promotion" to articles that treat it with undue disrespect. In this context, "we" don't use "aeroplane" or "airplane" (why, I can't fathom either, if it's relevant) but substitute "fixed wing aircraft". I quite agree this is silly - the point has in fact been argued quite a lot at the article I suggested you read and in other places. I know the ground that "fixed wing aircraft" covers and what it excludes at least as well as you do. "Aircraft" which is what I would prefer, especially when there is very little risk of airships or balloons being seriously taken as part of the field we are discussing, also tends to be frowned on. And then there ARE people (read my last post again, please) who hesitate to call the B-36 a pusher. NOT because some models had auxillary jets (if you want to be taken seriously and not as a kind of bad joke why bring that up time and time again after I have said at least twice before I fully agree that is nothing to do with it?). It has six pusher propellers, so if that is your full definition of a pusher then it is one by your definition (and mine just quietly). But other people define a pusher more narrowly than that. You and I would both probably agree that they are "wrong" (whatever that might mean). But by stating the underlying fact about WHY we say it was the world's largest pusher (that great row of pusher props) there is very little the "true pushers have just one pusher prop, and it is on the centre line" brigade can say. We have added a succinct, sensible, NPOV explanation of why (for the purposes of the statement we want to make about the B-35 being the biggest pusher) it IS a pusher.

Hang in there, do what I do, and NEVER go near a computer keyboard (at least one connected to the net) when you're feeling like THAT. (Grandfatherly advice, in case I am old enough to be yours, which I suspect I might be). --Soundofmusicals (talk) 06:27, 18 October 2011 (UTC)

Nope - maybe closer to my father. I am old enough to have grandkids of my own. :) Offend not so much - startle yes. Intentions do go awry. Doesn't help that I should have gone to bed about 3 hours ago and I have been dealing with idiots for the last few days. I was having a quiet edit on the flaps page (made a new graphic showing all the different types - bet there are ones you've never seen) and somehow ended up here, saw a seriously messed up definition and couldn't leave it for tomorrow. Live and learn - thanks - your reply has cheered me up as well.

I think that if the defintion is sufficiently well sourced, and sufficiently specific in what is covered (and what is not), any silly semantics trying to tighten the definition beyond the bounds of reasonableness can be nipped in the bud. Staying away from ww1 and 1930's sources might be plan.NiD.29 (talk) 06:59, 18 October 2011 (UTC)

Now THAT's an apology I CAN accept! (And do). Not that you actually needed to "explain" anyway. Incidentally - noticed you crossed swords with Graeme about the B-36 - at least you can see I'm not kidding about ye good ole "house style"! I have been bold - stuck in "aircraft" for "airplane" (bugger airships)- with the same wikilink to "fixed wing whatevers", and put in something for anyone who might say "but its just another big multi-engined piston engined aircraft with its propellers the wrong way round - THAT's not a pusher as such you know" IN A NOTE. No longer interupts the main text, and it is at least there.

Talking about notes - had a look at note 1 (NOT mine at all by the way) and of course the examples ARE tractors not pushers, although they do have rear mounted engines (!) I presume this is the point that the editor who inserted the note was trying to make - it is of course not clear from the text. I have mentioned this is the right place.

So far as dated sources go - nothing wrong with them if we put them into historical perspective, which was of course exactly what I was trying to do. Still may ditch them (If Graeme will let me!).

Popping off to have a look at those flaps! --Soundofmusicals (talk) 08:06, 18 October 2011 (UTC)

Rather busy to day, so not really in a position comment at the moment. But on the airship front, the largest airships were about 5 times the length of a B-36, more than half as wide and of similar magnitude of weight. GraemeLeggett (talk) 11:54, 18 October 2011 (UTC)

Intro Proposal

That said, I would like to propose that the introduction paragraph be replaced in its entirety with the following:

A pusher aircraft is a propeller powered airplane in which the propellers are mounted so as to be behind the respective engines to which they are attached. Due to balance constraints, this normally means that the engine or propeller is mounted behind the centre of gravity, either near the trailing edge of the airplane's wing, or further aft.NiD.29 (talk) 05:40, 18 October 2011 (UTC)

Good thought - I like it. There is the basis for a very sensible "initial" definition there - even if it it doesn't QUITE say everything we want to say - and they'd LOVE us to work in those references. Give me time to have a cup of tea and I'll work on it a bit! --Soundofmusicals (talk) 06:35, 18 October 2011 (UTC)

Having a first look at yet another new "definition", using Mr Nieuport's definition above as a starting point - now what about note 1!!! This actually lists TRACTOR aircraft with engines and propellers well behind the wing, proving that our (very old) sources' definitions don't stack up against modern "light aero fantasy" very well at all! Its not all that clear from the text that this is in fact the point being made, so this is one thing will have to be clearer (assuming we keep it in at all). --Soundofmusicals (talk) 07:39, 18 October 2011 (UTC)

I have been "bold" and added the new definition etc. to the lead - this is based on our discussion above. Just so no one can blame me for any changes anyone else makes, here is the original text of the new lead, as I originally composed it:

In a pusher propeller powered aircraft the propeller(s) are mounted behind their respective engine(s). as opposed to the much more common tractor configuration, in which the engine(s) are mounted behind their propellers. Due to balance constraints, this normally means that the engine or propeller is mounted behind the centre of gravity, either near the trailing edge of the airplane's wing, or further aft., and in fact the pusher configuration has sometimes been defined in these terms On the other hand some modern, unconventional propeller driven aircraft designs actually mount tractor propellers behind the c.g.

To convert a tractor engine and propeller combination to pusher operation - it is not sufficient to simply turn the engine and propeller round, since the propeller would continue to "pull" driving the aircraft to the rear. Assuming the engine cannot be run in the reverse direction, the "handedness" of the propeller must be reversed. The loads on the thrust race are also reversed, as the pusher propeller is pushing into the engine rather than pulling away from it, as in a tractor. Some modern engines designed for light aircraft are fitted with a thrust race suitable for both "pushing" and "pulling", but others require a different part depending in which sense they are operating.

Early pushers more or less standardised on the so-called "Farman" type - which may be summarised as "a single propeller on the centreline immediately behind the wing - rotating between booms supporting the tail". Other early pusher configurations were actually relatively minor variations on this theme. Pushers have since been designed and built in many different layouts, some of them quite radical, these are covered in the section on "Pusher configurations", below.

---Soundofmusicals (talk) 13:48, 18 October 2011 (UTC)

Excellent work! I think that should cover all the bases. :) NiD.29 (talk) 15:40, 18 October 2011 (UTC)

A thought

I wonder if we have a problem here with conflating a "pusher aircraft" with "pusher engine". This came to me after tweaking the current lead. The note identifies the Radab Windex as a tractor configuration that meets the pusher aircraft criteria. To my mind, its engine is in tractor configuration, but the overall layout is a pusher aircraft. We still have problem with referencing.

• tractor configuration is entirely unreferenced and therefore of no help in identifying a uncertain "pusher" as a tractor.
• ideally, any aircraft listed needs have a reference supporting that it is (or is not) a pusher.

GraemeLeggett (talk) 18:12, 18 October 2011 (UTC)

Windex, Orlyonok (small eagle) and e-Genius look like gliders, as if there was no engine, with just a prop installed for max efficiency. One can add the example of the glider (propeller belt drive), too. But the glider and tractor layouts are quite similar, and conventional. I am surprised that you qualify the Windex layout as a pusher.Plxd (talk) 21:23, 18 October 2011 (UTC)

The Windex may have the engine and propeller mounted at the rear, but the installation is a tractor installation - not a pusher since the prop is on the front of the engine. A pusher aircraft is any aircraft that has a pusher engine regardless of where they managed to put it, so there is no conflation. For anyone still unconvinced, it should be possible to contact the company at mail@windex.se. The point of this page is to define exactly what constitutes a pusher (as I believe it now does - and with references that are beyond reproach). To repeat... From "The Cambridge Aerospace Dictionary" (2004), written by Bill Gunston, one of the foremost aviations writers in the world today and author of more aviation books than most aviation enthusiasts will ever read, recipient of the OBE for his "services to aviation journalism", and a Fellow of the Royal Aeronautical Society says: (quote)

• pusher aircraft One with pusher propellor(s) only
• pusher propeller One mounted behind engine so that drive shaft is in compression

(end quote)

NiD.29 (talk) 22:32, 18 October 2011 (UTC)

References

Definition

The definition begins with "In a pusher propeller powered aircraft". In "xx powered aircraft", "xx" qualify the engine, not the propulsion device. For example in "human powered aircraft", "human" is the engine, not the propeller. So I propose "In a pusher propeller-driven aircraft".Plxd (talk) 21:23, 18 October 2011 (UTC)

Sounds like semantics (I've seen it used both ways) but I see no reason anyone would have a problem with using driven.

Could be a steam-powered too (there was at least one successful steam powered airplane, and one I believe that was cancelled before flying, though neither was a pusher).  :)     NiD.29 (talk) 22:10, 18 October 2011 (UTC)

I've no problems with "driven" instead of "powered", Plxd, if that's what you mean - I can't see an important difference in the meaning. I can't see the point of the other reversions that restore all the previous faults of the definition either - I am very glad I pasted my altered definition above - that really needs to go back more or less as it was! In fact I have lost patience with this altogether - giving wiki (at least this topic) a complete rest. --Soundofmusicals (talk) 22:33, 18 October 2011 (UTC)

Two remarks. "however this was largely due to the limitations of aircraft at the time - the designers ...". This remark is valid for Barber (1917) but not for Roskam, 1985 book. Orlyonok is a 1972 aircraft; extremely light engines (turbo-prop) are 1960s dated.
"...tractor configured airplanes with the engine and propeller elsewhere." As the note giving the examples is removed, this does not help the reader understanding.Plxd (talk) 09:09, 20 October 2011 (UTC)

The definition begins with "aircraft" and continues with "aeroplane/airplane" without explanation. In fact, this article describes (without telling it first clearly) only pusher airplane layout. Maybe this is obvious for you, but for a non-specialist ? Also, a reader can search for "pusher configuration" as a thrust device only, so including airships, autogyros, ground effect machines, etc. The tittle and the definition (first sentence) do not clearly exclude that point, either. I propose :

"A pusher is commonly referred to as a propeller-driven airplane of wich the propeller(s)...

and/or, why not, to rename the article as "Pusher airplane" or "Pusher airplane configuration". Plxd (talk) 15:16, 20 October 2011 (UTC)

Renaming the page makes sense to me since the direction the engines are on airships etc aren't usually used to differentiate them as it is with aircraft. I am attempting to hunt down his book - I suspect like many recent books on aerospace engineering it is interested in only a limited number of options and has written it to avoid more complex alternatives. I doubt Roskam, if asked, would consider any of the tail mounted tractor installations as pushers even with his statement but I could be wrong - and their inclusion in the header really just confuses matters. Going through all the online copies of his books I can find, most of the propeller stuff has been redacted however p.337 of Airplane Design Part III: Layout Design of Cockpit, Fuselage, Wing and EmpennageL Cutaways and Inboard Profiles (2002): Talking about the use of extension shafts to propellers...

• This design approach has the advantage of giving excellent control of the c.g. location of an airplane: putting engines and propellers all the way back in an airplane can lead to stability problems which may be impossible to solve.

Impossible problems may have been deliberately ignored, especially in a textbook, and eliminating their possibility might be an attempt to reduce divergent discussions.

I just called the Canadian Aviation Museum (to see whether a trip would be worth it) and had their librarian check but despite having literally hundreds of books named "aircraft design", they have nothing of his (and they do have a massive collection of books - several times the size of the EAA library for instance). Any chance anyone who has a copy of the book could scan the requisite page(s)? Alternatively I may have to go to interlibrary loan.NiD.29 (talk) 19:09, 20 October 2011 (UTC)

Aircraft covers anything mechanical that flies, and airplane is specific to those aircraft that use fixed wings to generate lift (eliminating helicopters, autogyros, ornithopters and metaplanes).NiD.29 (talk) 19:13, 20 October 2011 (UTC) ...but then airplane and aeroplane would have to both be used which would add confusion so I changed the link so it is fixed wing aircraft as per the name of the page linked too - I think this will have the least possibility of confusion.NiD.29 (talk)

Are not most autogyros a pusher configuration? MilborneOne (talk) 19:32, 20 October 2011 (UTC)

Maybe (some are, some are not) but they are not airplanes/aeroplanes/fixed wing aircraft but rather just aircraft and so are not under this definition. Could probably add them though (being specific to exclude other non-airplane aircraft)NiD.29 (talk) 21:43, 20 October 2011 (UTC)

The definition has subsequently been edited to re-elevate the deprecated descriptions. I finally found a copy of the book in question and the author does not define a pusher as having a prop behind the cg, but rather says most pushers have the prop behind the cg - a huge difference. The full quote is: "As a general rule, when the propeller or inlet plane is ahead of the c.g., the installation is referred to as a tractor installation. when the propeller or inlet plane is behind the c.g., the installation is referred to as a pusher installation."

By saying "as a general rule" he is says most - but not all, and the entire statement is then useless as a definition. Furthermore, despite the author's credentials, it was not published, but was hand typed, and so lacks the credibility of an equivalent properly published source.NiD.29 (talk) 21:12, 23 October 2011 (UTC)

Why not just say that in a tractor engine the propeller faces the front of the aircraft, whereas in a pusher engine the propeller faces the rear.

After all, it's really quite simple; on a tractor installation the thrust from the propeller is used to pull the aircraft through the air, in a pusher installation the thrust is used to push the aircraft.

BTW, tractor and traction both mean pull or pulling - hence the names. That's why a 'tractor' aircraft engine installation is so called, because the propeller pulls on the aircraft - a 'pusher' does the opposite - it pushes - hence the name. — Preceding unsigned comment added by 95.148.220.15 (talk) 11:43, 7 February 2015 (UTC)

Sadly, there was a very persistent editor who had misused several quotes to claim that the location of the engine made it a pusher, not the direction. Actually both pushers and tractors spin props whose rotation generates lift in line with the axis of direction of the prop, which can be broken into both pulling (Bernoulli's principle) and pushing (Newton's Third Law), so the simplest explanation supportable by references was to relate to how it acts on the engine it is attached to.NiD.29 (talk) 20:22, 16 February 2016 (UTC)

Article unclear

Tried to read the article but it is not clear what the purpose of the article is at the moment it is just a mixture of random ideas like Most built Pushers perhaps it needs a think about what it is trying to do. MilborneOne (talk) 19:25, 20 October 2011 (UTC)

For some reasons (listed in "disadvantages"), pusher (propeller-driven) airplanes are rare birds. "Most built" figures give a weight of that in a better way than an alphabetic list. "Configurations" gives a summary of existing layouts, trying to allow some understanding of how a pusher may be designed. Plxd (talk) 08:55, 21 October 2011 (UTC)

Canard layout

"In canard designs a smaller wing is present at the front of the aircraft to provide pitch stability or control."
Oops! Not the first time I read that; lot of articles or even "serious books" repeat that; in "Unmanned Aircraft Systems: UAVS Design, Development and Deployment", one can read page 35 : "A canard configuration has the horizontal stabilizer, or foreplane, mounted forward of the wing". A canard (lifting or not) surface looks like a stabilizer (same general dimensions) but is not stabilizing at all; as located ahead of the CG, it is strongly destabilizing. It provides added lift and/or pitch control. The aft wing (the horizontal tail or the main wing in the canard case) IS always the stabilizing surface. The pitch stability comes from the lift slope difference between the front and the back surfaces. "Canard layout" section purpose is not to explain what the frontplane does. Plxd (talk) 21:44, 20 October 2011 (UTC)

Propeller P-effects

"removed statement re rudder input to counteract propwash - effect is cause by p factor, not propwash and is still present, propwash may however mess up lift characteristics of wing root, etc)".

Yes, takeoff condition (steady course) was lacking. According to "Design of the aeroplane", pages 304-307 : P effects are mainly assymetric blade effect, producing a pitching or a yawing moment. That comes if the prop is not at right angle, or if the aircraft is moving (pitch or yaw), adding inertial effects (rigidity and precession). During the takeoff, under steady conditions : prop disk perpandicular to the velocity and without neither pitching or yawing, there are no such effects, but only rotating propwash effect onto the vertical tail if it exists. So the conventional tractor/canard pusher difference.Plxd (talk) 10:07, 21 October 2011 (UTC)

The problem is that there are some tractors and some pushers that lack either of these effects. A tail dragger with a pusher mounted above the fuselage may have little of no propwash over the tail, yet the same design when built as a pusher has some propwash over the tail because the engine could be mounted lower (the fuselage having to be taller at the front for the cockpit). Both have p effects though because of the initial high angle of attack when on the ground.NiD.29 (talk) 21:38, 21 October 2011 (UTC) Forgot to add that in cases where the engine is mounted up high, there has to be a significant angle between the thrust line and the direction of travel or it won't work properly, which means that this configuration has p-factor effects even in level flight. NiD.29 (talk) 00:50, 22 October 2011 (UTC)

Scope of the article

It seems that the initial purpose of the page was just a Pusher airplane history and description.
"Pusher configuration" asks for description of pusher thrust devices and machines using pusher devices.

1. in pusher thrust devices, we have propeller and ducted fan

2. in machines using pusher devices, we have :

aircraft :

aerostat pusher (airship)

aerodyne pusher :

rigid wing (airplane, WIG,

flexible wing (UL trike, paramotor, powered parachute)

rotor wing (autogyro)

others :

hovercraft

airboat, hydrocopter

maybe others

...a lot of topics. So, what to do ? focus on pusher airplane or follow this extended list ? Plxd (talk) 15:25, 21 October 2011 (UTC)

The important aspects are: (as I see it)

1. definition pusher vs tractor (done now I think)
2. a mechanical description re: bearings and props
3. advantages vs. disadvantages (limited to only those that are always specific to pushers) - this might be better as a paragraph than as a list since many advantages are tied to disadvantages and it makes the whole section unweildy when they are split.
4. some discussion of each variation with examples - farman, multi-engine, extension shafts, over fuselage, wing trailing edge, tailless/canards, oddballs, non-aircraft uses, notable exceptions, etc - with some background history (but not too much) to tie them all together. NiD.29 (talk) 21:51, 21 October 2011 (UTC)

About "advantages vs. disadvantages" : the existing splitted (harsh ?) approach allows to analyse (and correct) each point clearly. What we are doing. In a second step, when every item is ok, I agree a more textual (paragraph) presentation is smarter. But not easy to write without a lot of "although, however", and long multi level sentences. Last point, variations/examples would and will be nice (asking for quotes, too). The very object of the article.Plxd (talk) 08:56, 22 October 2011 (UTC)

I undersatand why it was done that way - however many of the points are so interrelated that it may not be the best approach in this case. Many disadvantages are specific, not so much to pushers, but to specific pusher designs, and may also be present in some (admittedlty unusual) tractor aircraft. Of course since the article now includes non-aircraft, even more of it seems out of place. (ps I added a space between my previous comment and yours for clarity). BTW there is also the aeroski (my name - not sure the russian word) - kind of a russian swamp boat, but running on skiis, complete with propeller - though most I have seen were tractors (frighteningly enough). NiD.29 (talk) 00:07, 24 October 2011 (UTC)

Interesting pushers, too. Russian name of propeller-driven sleighs is aerosani (not aerosan), sani means sleigh. Aerosani is a WP article. We have also prop-sleigh, aerosleigh, aeroski (?). What generic name type looks better ? Plxd (talk) 17:38, 26 October 2011 (UTC)

article used to be at Aerosan (seems to have been mmoved with little discussion).GraemeLeggett (talk) 18:11, 26 October 2011 (UTC)

just read the aerosani discussion. According russian speaking (in my family), "san" is not correct, it is always "sani", like scissors or trousers in english. The whole article begins and goes on with aerosani (except the title, strange enough). Plxd (talk) 21:01, 26 October 2011 (UTC)

Title : aerostatic-aerodyne

The writer has to choice : either Aerostatic and aerodynamic, or aerostat and aerodyne. Aerostat means an aircraft lifted by aerostatic forces; conversely an aerodyne is an aircraft lifted by aerodynamic forces, so aerodyne aircraft = aerodynamic aircraft aircraft. plxdesi — Preceding unsigned comment added by 89.3.150.181 (talk) 20:40, 6 March 2012 (UTC)

Safety, POV concerns

I don't have time to work on it now, but while the discussion above seems to be about semantics, has anyone really reviewed some of the assertions? They seem to be entirely speculative (particularly those about safety) rather than based on any study of accident statistics. From personal knowledge I can tell you that many pusher aircraft have fuel lines going through the cabin and are just as much of a concern that way, that in a crash a pusher is if anything more hazardous because the engine wants to continue moving forward into the cabin while the rest of the plane has come to a stop, and the claim of propeller fragments being a hazard to the cabin occupants in a tractor configuration (and in a pusher, less so) are all entirely specious. They might apply to a specific aircraft but certainly not to all pushers.

Many who are new to aircraft design consult Wikipedia as their first source of information and it's important to qualify partial truths rather than state them as absolute. Altaphon (talk) 02:53, 4 April 2013 (UTC)

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Quite unbalanced assessments

To me (tech. eng.) the whole comparison-section "tractor vs pusher" appears to be strongly biased. 46.114.0.52 (talk) 14:40, 13 June 2023 (UTC)