Talk:Ekranoplan
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Ekranoplan is part of WikiProject Soviet Union, an attempt to better organise information in articles related to the Soviet Union. If you would like to participate, you can edit the article attached to this page, or visit the project page, where you can join the project and/or contribute to the discussion. |
I've removed the following paragraph from the article for the moment because I don't see the justification for it.
- The term ground effect vehicle is often misapplied to hovercrafts, which use fans to form an air cushion (hence the correct term air cushion vehicle) rather than relying on true ground effect.
Firstly, the article is about ekranoplans, so it seems a bit out of place. Secondly, I disagree with the paragraph's claims, the hovercraft's air cushion is very much a ground effect, otherwise a hovercraft would be able to rise to an unlimited height. Both ekranoplans and hovercraft rely on an aircushion (a volume of pressurised air) to support them. The main difference is that the ekranoplan uses the ram effect of its forward speed to produce the cushion below its wings whereas the hovercraft uses fans to produce the cushion below its body. The difference is analagous to the difference between the aeroplane, which uses forward speed to produce lift, and the helicopter, which uses what is, in many ways, a large fan to produce lift. As a result the advantages and disadvantages of the two types of aircushion vehicle are analogous to those of the two types of aircraft as well. -- Derek Ross
- I disagree - hovercraft do not use ground effect. "Ground Effect" is a specific term referring to an aerodynamic phenomenon resulting from an aerofoil operating close to the ground (as a rule of thumb, within one wing-span of the ground). A wing works by creating a region of high pressure below it and low pressure above it (the exact reason for this is complex, and is often simplistically explained as a result of Bernoulli's principle, although that is only a small part of the story. Anyway, it is largely irrelevant to this discussion). Because of the pressure difference, there is a tendency for the air below the wing to move to above it. It can't do it by going over the leading or trailing edge, but it can do it around the wing tip. Thus, what is known as 'spanwise flow' occurs, where air under the wing moves out towards the tip, while air above it moves in towards the root. At the wing tip, this creates vortices (these vortices can be very powerful - a heavy airliner's wing tip vortices pose a major hazard to smaller aircraft). Unfortunately, these vortices cause drag (known as induced drag) This is why winglets are fitted to some aircraft, to reduce the vortices. Another thing to consider is that behind a wing, there is a downwash - this is again a natural part of the aerodynamics of a wing - as the air passes over the wing, it is deflected downwards (this is a result of the Coanda effect, and is a major factor in the production of lift). However, this downwash also results in induced drag. As an aircraft speeds up, induced drag actually reduces. However, the other form of drag, known as parasite drag, increases.
- Anyway, lets get back to the topic of ground effect. When an aircraft is close to the ground, the vortices can't form fully while the downwash is also reduced, leading to a reduction in induced drag. Because the parasite drag is small at low speeds, an aircraft flying in ground effect experiences a lot less drag than it would flying out of ground effect. This means it can fly without using as much power, which is the major advantage of a WIG/GEV/Ekranoplan etc.
- This is the major factor behind Ground Effect. While there is also a cushioning, it is the significant reduction in drag close to the ground which is the major issue here. It is very different to the concept of the hovercraft. You are quite right to say the difference between the two is analogous to that between Aeroplanes and Helicopters - there is a major difference between Ground Effect Vehicles and Hovercraft, and it is a mistake to confuse them. Nick Moss 12:46, 23 September 2005 (UTC)
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[edit] American intelligence "confused"?
I tend to doubt that American intelligence was bewildered by this if they got pictures of it. Ground effects flight is pretty well understood. What is the source of this info?
- I recall a documentary saying that US intelligence analysts were initially puzzled by the satellite photos which appeared to show an enormous, unfinished aeroplane. They consulted technical experts, who conjectured the 'Caspian sea monster' was a ground effect vehicle. I'll remove the 'confused' bit until someone can supply better information. --Townmouse 00:40, 2 April 2006 (UTC)
[edit] Compared to hovercraft and aircraft?
I'd like to know more about its advantages and disadvantages to hovercraft, flying boats and ground-based transport aircraft, especially fuel consumption per kilometre, cost of production and cross country performance/seaworthiness.
The number of possible military applications of this vehicle must be somewhat limited - did the Soviets create it to fill a specific role, say delivering a large invasion force by surprise, or was it more general-purpose?--81.178.70.200 12:52, 3 April 2006 (UTC)
- Military uses limited? You ask the some logistics people what they think of 400km/h 1000 ton lift craft that can run all the way from supply ships to the forward supply dump without requiring dock facilities. --88.96.3.206 19:22, 22 July 2006 (UTC)
- I agree. A force of these could potentially slip under the radar and deliver a fully armed and equipped force of Soviet T-80s to the East Coast of the United States. Their lift capacity is unrivaled.--TelevisedRevolution 23:59, 19 October 2006 (UTC)
[edit] More information on Ekranoplan?
Over the past few days, I have developed quite a big interest in the Ground Effect Vehicles. As a result, I have done a frightening amount of reading into them. Unfortunately, when it comes to editing the Ekranoplan pages in wikipedia, I don't really have the confidence to put my money where my mouth is, even if my sources are good. So, these are the sources I've found, which I'm confident could be used to good effect.
Scary documents:
Foreign Military Studies Office - The Tyranny of Time and Distance: Bridging the Pacific.
http://fmso.leavenworth.army.mil/documents/bridge/bridge.htm
While this site is in Russian, and probably doesn't qualify as a notable source, it seems to have some pretty in-depth information about the Espa-Y class of Ekranoplan.
http://mkmagazin.almanacwhf.ru/mk_other/okb_mk/8309_ekranoplan.htm
This USAF study may be relevant in some way, but the complexity of it causes my brain to palpitate.
http://www.ndu.edu/library/ic6/95-S12.pdf
Other links
This site contains a diagram of the development of the various Ekranoplan classes.
It's in French, but its sourced as from "Science & Vie" (Science and Life) which is a French science magazine. One problem is that it labels the first Ekranoplan as Utka, and the anti-ship Ekranoplan as "Lun Militaire", whereas the FMSO article (and another chart I have yet to find a reference for) describe it as Utka.
http://membres.lycos.fr/dracken/Ekranoplan/historique.html
AlphaSim have created an Ekranoplan for use in Microsoft Fight Simulator 2002 & 2004
http://www.alphasim3.com/store/product_info.php?cPath=26&products_id=67
I currently have emails out to some people, who might be able to give me more reliable references, but I'm not holding my breath on it.
Kirai no Tenshi 14:55, 12 August 2006 (UTC)
[edit] Veracity of Bentley Yachts
I am hoping that somebody can further verify this source. I can't find anything about the company or its founder on Google other than its own pages. Most of the boats they have for sale are CGI renderings, and their ekranoplan pages simply have photos sourced from elsewhere and obscure the vehicles' Soviet military origins. I remember reading an article a few years ago which said that the design bureau in charge of the Lun model was looking for a private buyer for the one that had been mothballed, but I haven't been able to find that article again; otherwise I would replace the Bentley link. Until then, I'm hoping somebody can get some more information on this company and their ties to the Soviet ekranoplans, if they're for real.
oops, forgot to sign istewart 10:12, 30 October 2006 (UTC)
"Two types (Lun and Orlyonok) appear (October 2006) to be available commercially, as private 'superyachts': http://www.yachtboutique.com/Designers/Ekranoplan/Ekranoplanintro.htm"
I think I'm going to remove that line - that site is almost certainly a joke site! --80.43.107.254 23:18, 31 October 2006 (UTC)
