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I've taken a picture and stuck it on here for now, hoping it will make it easier for readers to visualize the device; it's not a good picture, though. The model is fairly unlike Hero's original, and the photograph is poorly composed. If anyone has a better one, I hope we can replace this quickly! -FZ 23:58, 3 Aug 2004 (UTC)
- The acticle I linked to has a good image, which fits what I understand it to look like; Of course, I'm no expert, and I guess we'd need permission to use it. Barring that, I've been making a 3D animation of the aeolipile, a still of which could be used, but a photograph would definately be preferable. --GalanM 05:23, Aug 4, 2004 (UTC)
- Okay, I've added the image. Turns out that the image was from a government site, and therefore public domain.--GalanM 21:05, Aug 8, 2004 (UTC)
- Lovely work. -FZ 12:39, 9 Aug 2004 (UTC)
I have video of a running Hero's engine from my glass shop class this last year - it's a little out of focus, and the engine is glass, but it still definitely gets the point across of how they run. If I put it on Youtube, would it be useful to add a link to it in this article? (Or is there some better way to reference videos in Wikipedia articles?) Splowey (talk) 01:45, 1 August 2008 (UTC)
- You can certainly add a link to YouTube, although there are numerous such Aeolipile videos there already. Better would be to find out how to add it to Commons, since then you'd be able to have the video visible and running here, not just as a link.
- EdJogg (talk) 18:39, 13 August 2008 (UTC)
Can this thing do a useful amount of work?
Is escaping steam an efficient way of using the energy?
A steam engine builds up pressure inside its boilder to severals atmospheres, and the higher the pressure the more work it can do.
The boiler of the Aeolipile works at 1 atmosphere, so its poer potential is surely very small.
Tabletop 08:50, 29 May 2005 (UTC)
- There's no reason that the boiler would have to be at 1 atmosphere. To a fair degree it depends on how much heat you put under it. Beyond a certain point the jets will do what's known as 'choke' and then the pressure can go above 1 atmosphere.WolfKeeper 17:17, 13 September 2006 (UTC)
- The question remains of had he connected some sort of machine to it and made it do work, would he have developed the idea into something that could do useful work. Seeing that it couldn't produce enough energy to do much work, he might have attempted improved/alternate designs that had more power. All of the basics exist in the aeolipile, it just needed some thought into how it could be used. -GamblinMonkey 04:09, 25 April 2006 (UTC)
- It was used in a small way to open doors in temples and such like.WolfKeeper 17:17, 13 September 2006 (UTC)
- It certainly CAN do physical work. The main cause of confusion is the question of wether the Greeks actually put such an engine to practical use. There's some debate over this, but I think that on the ballance of evidence they just viewed the aeolipile as being a "toy". Regardless of any practicalities/historical use, the dynamics go something like:-
- accelerating Torque = Force of Rocket/nozzle * radius of action "nozzle"
- decelerating torque = - Aerodynamic drag force * radius of action "drag"
- accelerating torque + decelerating torque - net OUPUT torque = 0
- OUTPUT power = OUTPUT torque * Revs/second
- the force of the rocket/nozzle can be computed using the equations for Rocket_engine#Net_thrust
- aerodynamic drag forces are a LOT more difficult to compute without using Computational fluid dynamics but perhaps the Drag_equation is of some use in understanding what's going on.
- steve10345 (talk) 17:49, 7 September 2008 (UTC)
pile: ball or gate?
Although Pneumatika has survived in greek I could only find an online version translated in english (searching Heron's external links).
- Heron's Pneumatika: Temple Doors opened by Fire on an Altar
- Heron's Pneumatika: Other intermediate means of opening Temple Doors by Fire on an Altar
- From Heron to Worcester
- Heron's Pneumatika: Sounds produced on the opening of a Temple Door another project of Heron.
So Heron used this invention to open temple door with help of wind and perhaps this is how the term aeolipile occured. But we can only verify that 100% by checking a copy of Pneumatika in greek and see how he spelled aeolipile etc. MATIA 11:31, 19 August 2005 (UTC)
- None of the spellings seem to be listed in the standard ancient Greek dictionary... AnonMoos (talk) 02:51, 4 July 2009 (UTC)
An aeolipile is not a rocket
An aeolipile is a rocket-like device, but it was not the first rocket.
The first reaction engine, the aeolipile (a ball that rotated as a reaction to escaping steam), was constructed by the inventor Heron (or Hero) of Alexandria. Developments through the centuries have resulted in two general types of reaction machines, the true rocket and the airstream engine, commonly known as the jet engine. Unlike a jet engine, a rocket engine carries with it chemicals that enable it to burn its fuel without drawing air from an outside source. - The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press
--Sean Brunnock 13:15, 13 September 2006 (UTC)
- Rocket engines *are* jet engines (as in an engine propelled by a jet). And lots and lots of sources say that the aeolipile *is* a jet engine. Given that they haven't defined what 'true rocket' means, it doesn't seem to settle the question. And I googled for 'airstream engine' and dug into the hits and essentially found only copies of this article on the web. They are defining aeolipile using non standard terms. Also, rockets don't have to involve combustion, there's steam rocket cars and water rockets and thermal rockets. This definition is flawed on multiple levels. WolfKeeper 15:34, 13 September 2006 (UTC)
- Careful here:
American Heritage Dictionary - Cite This Source new! jet engine n. 1. An engine that develops thrust by ejecting a jet, especially a jet of gaseous combustion products. 2. An engine that obtains the oxygen needed from the atmosphere, used especially to propel aircraft and distinguished from rocket engines having self-contained fuel-oxidizer systems.
- You gave us a definition for a jet engine. It states that they are distinguished from rocket engines. You seem to be shooting yourself in the foot. --Sean Brunnock 16:26, 13 September 2006 (UTC)
- Careful again. You apparently misunderstand dictionary definitions. When dictionaries number their definitions the definitions are distinct definitions. There are *two* definitions listed above, not one. Nobody is saying that a rocket is an air breathing jet engine, but it clearly is an engine that develops thrust by ejecting a jet; so it meets that definition of jet engine.WolfKeeper 16:35, 13 September 2006 (UTC)
- It's common to call non-combustion powered steam rockets, like the NERVA nuclear rocket, rockets. 18.104.22.168 23:55, 30 November 2006 (UTC)
MAD Magazine quote
- Image:21mad.jpg - The cover of Mad #21 (March 1955), which included an aeolipile as well as the début appearance of its eventual mascot Alfred E. Neuman" (the picture accompanying the 2010 submission of this test).
What's wrong with this? It's directly related to the subject matter...are we worried about copyvio?
- Mad Magazine spoofed the device in an article satirizing the popular mail-order house Johnson Smith, with this text:
What home is complete without a genuine, operating aeolipile? If you haven't gotten an aeolipile by now, send for one right away. After you've received and used it, you will say, 'How did I get along for such a long time without an aeolipile?' Aeolipiles can be used by the whole family. Show them that you too have an aeolipile. Imagine the surprise on the faces of your friends when, in the middle of nowhere, you whip out your brand-new aeolipile. Wow. The girls will really admire you when they hear that you have an aeolipile.
What right do we have to claim this is a spoof? The magazine was obviously selling them to the public. This article should be covering the reasons why they are no longer in use as domestic appliances / security devices / business toys, etc...
EdJogg 19:49, 18 July 2007 (UTC)
- Very glad to see that we now have a reference for this, indeed an image of the original 'advert', with this very text, is included there. Could we get away with re-instating this text now? -- EdJogg (talk) 13:01, 30 March 2010 (UTC)
- Why the hell does a historical article like this have a picture from Mad magazine at all? The fact that they put a picture of one somewhere on their cover, with some ridiculous text as a joke, doesn't mean it should be here. Dream Focus 00:20, 29 May 2010 (UTC)
- It's not uncommon for articles to include an 'In popular culture' section, to indicate the item's cultural impact. The 'lost' text (and reference) is here:
The aeolipile's unusual look inspired Mad Magazine to include the device as a visual element in various articles over the years, including the cover of issue #21 which parodied the popular mail-order house Johnson Smith Company.
This article has just been labelled as a stub. Fine, it is a short article. But how much more could we seriously expect to write about it?
Hero(n)'s description amounts to a single paragraph (in the translation) + a diagram. It might be useful to quote that paragraph here, and provide an annotated diagram. But what else?
If we cannot reasonably expect to expand the article, is there any point in keeping the stub templates in place? At what point can we make this decision? Is there a template to say: "yes-we-know-this-is-a-stub-length-article-but-there-is-little-more-to-add"?
I feel this article would be much improved, if the historic implementation(s) of this type of device were to be seperated out from the Mechanics of why they spin. The main problem areas as I see it are too do with the questions of "Were they put to work by Heron" and "How does it work/Can it be be used for useful work". The current article can be confusing, and is very susceptible to FUD(which doesn't help anyone!) because it doesn't take into acount that "engineers" largely consider the principles/physics of the device, while historians are more concerned about historic events/life. Both of these viewpoints are valid/verifiable, but it should be realised that are covering quite different areas:- hence my call for the subsections.
In the section on mechanics, a simple Free body diagram of the device seems warranted. It would help provide a clearer visualisation of the key components, and provides a good start for those who wished to detail/study it's motion in more detail. It should be said here that while it may be inefficent at doing so, it can certainly be used to drive a shaft/generator, and therefore Engineers would say it CAN generate useful work (using the defination of Work_(thermodynamics) as used by engineers). Also perhaps link to Catherine_wheel as their motion is produced in a very simlar manour to that of the aelipile's, because of the use of a Couple_(mechanics)
The "history" section should also make it easier for those more qualified in the device's history/background than I am, to verify why the device WAS NOT put to useful work in antiquity/ and hopefully give reasons for the confusion. Given the presence of a physics section, it would be nice to include possible reasons as to why wasn't used "back then", but perhaps this isn't verifiable as yet! IMHO it's probably all down to the relative costs (both of "fuel"/running costs and purchase) of the technology compared to using other forms of work such as animal/slaves for motive power. (To me that sounds like it's to do with [Energy_economics]] and forms a body of potential PHD material for an engineering historian??? ...and therefore probably not suitable for Wikipedia. YET!)
- Just for the record, it's likely to be horrendously inefficient. The tip speed is probably only a few meters a second in most cases, but the exhaust velocity is more like the speed of sound, or even several times that, so the propulsive efficiency is pretty much going to be in the dirt. The energy efficiency of the boiling steam is also lousy, the temperature reached is likely to be only slightly more than 100C, and it's exhausted not that much cooler, so the Carnot efficiency is also rotten. All in all, it's not going to be pretty, since you multiply those two efficiencies to get the overall efficiency.
- With modern design techniques, materials (e.g. Kevlar) and thermodynamic knowledge (i.e. run it at really high pressures and speeds) it's probably possible to get reasonable efficiency, but in antiquity... nah, it's disastrously bad.- (User) Wolfkeeper (Talk) 03:44, 19 February 2009 (UTC)
- Was more thinking of verifying/quantifying the efficency (well OK the lack of it!) by using a mix of Thermodynamic systems and a consideration of the forces involved in the machine(hence the suggestion to have a "nice" animated free body diagram!). IMHO it makes things a lot easier for the none-engineer to understand what's going on, if the forces acting on the machine WHEN it's reached steady state are detailed(NB i've forgetten how to deal with angular acceleration!) From them it can be explained how it's shaft power is generated, by using something like:
- Regarding Wikipedia:OR,
- peops might have got the wrong hang of what I'm trying to do here . I'm not trying to "prove" it works, but instead trying to detail the principles by which engineers understand how it moves (from which comes the assertion well known in engineering, that it can do some degree of useful work).
- A Free body diagram is just a diagram of the forces involved, and the forces involved have already been described here using words. (it's just a different way of organianising the infomation, and is common practice within engineering)
- given that it's such a simple device, and can be easily understood from First principles it's often used a teaching aid in schools, As such I'm SURE that the mechanics of its motion will be detailled in physics/engineering text books. I'll go and hunt through the secondary school Physics books/Engineering books at my town's Central libary.
- Final thought! Would it be OK to compare it's action to this [electrostatic windmill]? Both devices have a "wizzy round nozzles" which use the rocket principle to cause rotation. (The only real difference being the source of the "pressure" which powers the "rockets")
- steve10345 (talk) 21:27, 20 February 2009 (UTC)
Inventor or Describer??
I have raised a question on the talk page for Hero of Alexandria (see Talk:Hero of Alexandria#Inventor or Describer??) to determine whether Hero should be documented here as the inventor of the aeolipile, or merely that he described it.
Please comment there if you can shed light on this matter. Thanks.
- Hero was not the first to describe the aeolipile, Vitruvius published it nearly a hundred years earlier and does not take credit for the invention Granite07 (talk) 23:30, 2 July 2009 (UTC)
Would article be better under Technology / Engineering than Physics
I've noticed this article is currently under wikiprojects Physics. While the device certainly utilises principles from Physics and is often used to demonstrate such principles, would it not be better placed under technology? To my mind the distinction is physics describes things which can happen, where as technology is a utilisation of physics to control what happens steve10345 (talk) 16:55, 9 June 2009 (UTC)
- Why not both? If the Physics Wikiproject is happy to include it, who are we to argue? EdJogg (talk) 23:55, 9 June 2009 (UTC)