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Old 05-18-2013, 06:15 AM   #21
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The hassle is ground effect is only useful at altitude of about 1/2 the wingspan and under.

A 200 ft span means efficient under 100ft , but when making a turn probably kicking it around with the rudder would be a better idea than a coordinated turn.
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Old 05-18-2013, 10:27 AM   #22
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Very interesting Marin.

So you're saying the Russian flying boat dosn't fly? I think you guys are ahead of me as I'm lacking the plug in necessary to play the video so it seems I'm missing a big part of this.

Thank's on the tip touching.

FF .. it would seem to me that going 100 knots over the waves sideways in a flying boat could be other than desirable.

Marin I now recall the P-6 was scrapped because too much sea water went through the engines. That probably was the reason for those extreme spray rails on the Russian monster.
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Old 05-18-2013, 03:19 PM   #23
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Originally Posted by manyboats View Post
Very interesting Marin.

So you're saying the Russian flying boat dosn't fly? I think you guys are ahead of me as I'm lacking the plug in necessary to play the video so it seems I'm missing a big part of this.
Yes, it does fly, which is why they can go so fast. The Soviets built quite a variety of these things, not just the one in the photos here on the forum. Just enter the title of the great video Murray posted here in YouTube and you should be able to find the same video on your own if the link in the forum doesn't work. You'll even see the monster pictured here firing its missiles while underway.

But they fly in ground effect, which as I expect you already know, is a "force" that occurs when a plane is roughly half its wingspan from the ground. For reasons I don't really understand, when a wing is that close to the ground, induced drag (the drag that is automatically produced by the act of generating lift) is significantly reduced. This is the main contributor to an airplane's tendency to "float" down the runway after the pilot flares for a landing.

Like birds such as cormorants and other seabirds that use ground effect to reduce the energy they have to expend to stay aloft, the ground effect airplanes do, in fact fly, but very close to the water. This enables them to go quite fast, carry very heavy loads, yet require a lot less power and less wing area to do it than a conventional airplane of the same size and load-carrying capability.

Because they are flying so close to the water it is inevitable that they will touch it now and then if not all the time. If you watch the video you will see these things whizzing along just above the surface with spray trails coming off their wingtip floats and sometimes the aft end of the hull.

It's a very valid concept--- as I say, birds have been using it for eons. How practical it really is another story. The fact the Russians have retired all of theirs, although they claim they are going to revive the idea--- is pretty telling. On the other hand, the Russian GEVs are probably about as poorly built and unreliable as all the other crap they came up with back then. Great designs, horrible execution.

There is also the issue of the water conditions necessary for them to be able to operate. Flying along a few feet above calm water is one thing. Flying along over the open ocean on a bad day would most likely not be possible because in order to fly low enough to be in ground effect they would be slamming into big swells and waves and most likely come apart. The Russians used theirs on inland seas, mainly the Caspian Sea. So unless it was really stormy, the conditions were such that most of the time they could fly.
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Old 05-18-2013, 03:54 PM   #24
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The lift is actually from the heat created by the jets engines, which creates a cushion of warm air that goes in a circular motion under it, think of a tornado but horizontal that's what actually keeps plane out of the water. Their was documentary on these on the military channel.
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Old 05-18-2013, 04:16 PM   #25
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The lift is actually from the heat created by the jets engines, which creates a cushion of warm air that goes in a circular motion under it, think of a tornado but horizontal that's what actually keeps plane out of the water. Their was documentary on these on the military channel.
Hmmmmm.... I don't think that's really correct. Some of the Russian GEVs were powered by a huge turboprop at the top of the tail. No heat under the plane from them. Ground Effect has nothing to do with heat cushions. It's an aerodynamic principle and you get it with no heat-generating powerplants at all, as in birds.
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Old 05-18-2013, 04:29 PM   #26
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Thanks for the informative post Marin. As I said I can't watch the video.

I think ground effect is caused by the friction of the ground re the spanwise flow under the wing. The air under the wing can't move aside as easily as it can w/o the ground being close making it difficult for the air under the wing to move aside.

And yes I agree that ground effect vehicles have very limited usefulness.

Camano 31 I don't follow your theory?
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Old 05-18-2013, 04:35 PM   #27
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Here's a pretty good explanation of ground effect. But to understand ground effect, a short lesson on induced drag is helpful.

Induced Drag: In a nutshell, induced drag is caused by the flow of high pressure air (below the wing) around the wingtip to the low pressure air (above the wing). This cyclonic flow in free flight outside of ground effect causes a partial cancellation of lift on the outermost portion of the wing and an increase in drag....induced drag. This form of drag only occurs when lift is being provided by the wing (i.e. pressure differential between lower and upper wing).

Ground Effect: When flying at an altitude above the ground equal to or less than the wingspan of the aircraft, the ground interrupts the flow of high pressure air (below the wing) around the wingtip to the low pressure air (above the wing). This reduces the induced drag on that outer portion of wing and increases the lift that would occur during flight at higher altitudes.
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Old 05-18-2013, 04:53 PM   #28
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Fly,
Isn't that whatI just said?
In your explanation it was made clearer though I'm sure.
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Old 05-18-2013, 05:14 PM   #29
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Yup...same thing. We were probably typing at the same time as we posted within minutes of each other. You're faster on the keyboard and much more succinct.
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Old 05-18-2013, 06:34 PM   #30
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A couple of my friends actually built and flew a ground effect machine. They both had ultralight aircraft manufacturing experience so that is the technology they used.
They mounted a Rotax on an aluminum john boat making it into an air boat. Then they mounted stubby wings on the darn thing and flew it. They had trouble turning it and I think it crashed on the fourth flight. They had had their fun so they quit there.
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Old 05-18-2013, 07:57 PM   #31
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Fly wrote "We were probably typing at the same time" Yes I've done that too.

HopCar, Yea I've seen some ground effect things that were pedaled like a bicycle.
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Old 05-18-2013, 07:59 PM   #32
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Ground Effect has nothing to do with heat cushions. It's an aerodynamic principle and you get it with no heat-generating powerplants at all, as in birds.
I agree!
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Old 05-18-2013, 10:24 PM   #33
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And I agree
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Old 05-18-2013, 11:28 PM   #34
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Manyboats, I wonder if any of the various human powered aircraft have ever flown out of ground effect. Both the Gossamer Condor and the Gossamer Albatross had wing spans of close to 100 feet but I don't think they ever went higher than about twenty feet.
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Old 05-19-2013, 08:13 AM   #35
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I'm surprised you don't remember this, Eric.

Speed limit exemption for winged ships | Juneau Empire - Alaska's Capital City Online Newspaper

Pacific Seaflight Wingships

When I was working on the AMHS we kept waiting to be passed by one on the way to Skagway ...
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Old 05-19-2013, 10:07 AM   #36
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Very interesting Rick. And hits home as I was born there and my father was a reporter for the Empire.

I thought the high speed catamaran ferry was a joke too but it exists.

However I can't imagine a WIG coming out of Gastineau Channel into a Taku wind (broadside) coming out of Taku Inlet. And then up the "Big Lynn" in the winter I think the wind blows at least 100 knots and on occasion it does that at Lincoln Rock in Clearance Strait close to where we just moved from. The WIG may not even go 100 knots. Lots of things come and go and I suspect this is one that will go. May miss most all the logs though.

A lot better looking than that Russian thing.

HopCar, I don't remember.
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Old 05-19-2013, 03:59 PM   #37
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Quote:
Originally Posted by Camano 31 View Post
The lift is actually from the heat created by the jets engines, which creates a cushion of warm air that goes in a circular motion under it, think of a tornado but horizontal that's what actually keeps plane out of the water. Their was documentary on these on the military channel.
I just got a call from Giggitoni about this special on the Military Channel today. In all fairness to Camano 31, that's what they said.

"The eight jet engines in front are used for takeoff. They push hot exhaust under the flat rectangular wings, helping to lift them up onto a cushion of air. During flight, the two engines on the tail take over to power the Ekranoplan forward."


They even had the attached graphic showing how it was supposed to work.

They went on describe the difficulties it had with salt water spray on the jet engines and negotiating turbulent seas. In August 1967, it made its first flight. Ultimately, the early version was scrapped, as was its designer who was forced into retirement, only to die 5 years later. (hmmmmmm...) A later version complete with missile tubes along the top of the fuselage was designed to attack the US Fleet with 'aircraft' launched anti-ship missiles. Under Gorbachev's reign and the end of the Cold War, the idea was shelved.
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Old 05-19-2013, 04:17 PM   #38
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I can understand the engine-exhaust-under-the-wing to force it up into the air. But in the photos posted earlier of the missile-carrying GEV there are not any engines in the tail. There are a couple of huge bulgy things but they don't have exhaust nozzles and appear to be streamlined housings for radar or other electronics, perhaps for the missiles? But it would appear that the eight engines also kept the thing moving forward. At the end of the video that Murray posted this particular GEV is shown flying and there is no indication of engines in the tail--- no intake openings and no exhaust smoke

All in all, though, a very interesting and clever concept even though the execution left a lot to be desired. It would be neat if someone could make it work on a practical basis.
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Old 05-19-2013, 04:34 PM   #39
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http://www.youtube.com/watch?feature...&v=V8Nu94khHoo









History of Caspian Sea Monster & Ekranoplan
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Old 05-19-2013, 04:46 PM   #40
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Cool videos and drawings, thanks. I guess they had powerful enough engines on the missile GEV not to need engines on the tail. These things must have been amazingly noisy. Like B-52s probably.
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