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Nov 23, 2011, 11:34 PM
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@armour: Apparently, the designer of the Bateleur, Andre Von Schoenebeck, did not patent it, or at least not under his name or under the name of RMT. Too bad, we could have learn a lot through a patent. BTW, have you read RMT website? That Bateleur has some heritage: designed by the son of one of the Red Baron squadron pilot, no less. No wonder it flies so well!
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Nov 24, 2011, 05:42 AM
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RdsG's Avatar
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Quote:
Originally Posted by Vykhan
@Gabriel: That's a really nice find. Never seen that kind of hydrid design before. It seems it's mixing the tandem and Lippish idea, with a Lippish front wing and a tandem rear wing instead of the Lippish tail. Apparently, they had some take-off problem initially (first picture) since they added a front hull/ski to pitch it up in the bigger model (video) and the display model. But, as with other tandem wing, it seems to only flight very low (not good with waves). OTOH, replacing the front thin wing with a Lippish wing probably makes it more efficient. A good low powered WIG for large lakes and river between mountains (A Lake Geneva ferry?).
I tried to build several tandem wing glider but they a usually left the ground effect. A higher wing loading makes them more less sensitive, but it resulted low flying height. Actually this method works on other types too.
These models has a relatively big dihedral fins at the back. I guess they are not effected by ground effect so they act as OGE stabilizers. May be I try this one.
Nov 24, 2011, 02:33 PM
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hoverman's Avatar
Hey guy's, I haven't been working on my models for the last few weeks, actually the Bixel and Type2 Ekranoplan are both awaiting their next sanding session. To be quite honest I'm building a 3m Radio Telescope dish at the moment(another hobby which is running out of hand)

Anyway.. Gabriel, that Reversed Delta WIG glider looks nice and seems to work just as fine. You're right about the Japanese Wig Contest video.. those models do look familiar haha, on the other hand, my lippish is just another copy of the original Airfish craft Did you notice that the models in that video behave just like my model, they 'fly', but roll and pitch to all sides during every run, resulting in a sort of unstable dynamic flight pattern.

The video you found is great, I really haven't seen it before! Interestingly, in the book "Soviet and Russian Ekranoplans" there is a small text and véry bad photograph showing a 1person WIG called "Baikal-2", which supposedly never flew.. but it looks éxactly like the model in the video, only it's a bit larger! So they built a larger version.. according to the book it was placed into storage due to funding problems before testing ended.

@ Vyhkan - The bataleur is a very nice plane, but I still can't find any video footage of actual Ground Effect flight? Surely it's flying close to the ground in the video, but that's not Ground effect flying. Surely the Ground will influence it's flight pattern at those altitudes, but the effect's are minor enough for the pilot keep it stable.

I am a pilot myself and I can tell you, even small planes, Piper Warrior, Archer, Diamond Twin Star, even with Flaps Down.. that's no Ground Effect flying! With a little bit of training, a steady hand and no gusting wind, it's quite easy to cruise along the whole runway 'flairing', with the weels about 30cm off the ground. As we all know, the main stability issues in Ground effect are caused by Chord Dominated Ground effect, and normal planes never descent low enough for this to occur because the gear is in the way the Bataleur is flying wáy too high for Chord Dominated GE and thus it doesn't suffer large stability issues when flying low... it simply still flying like a plane.

@ Captarmour - I try to keep up reading through all the posts, all I can say is keep up the good work

Best Regards to all!

Marijn
Nov 24, 2011, 02:54 PM
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Vykhan I have no info just common sense guesses that are probably dead wrong!

Marin is right its not a wig, maybe I don't really want a wig...maybe just something I can build and fly without caa getting involved.

I like the deltas because oge they seem stable, kinda like an arrow all the wing behind. It would be nice to plane like a boat on take off with just a bit of hull in the water.
Nov 24, 2011, 03:03 PM
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Hi Marijn!

Thanks for the key words! "Байкал-2 экраноплан"

It uses a weird combination of a low aspect ratio wing and a reversed delta(?) wing as a front wing...

http://www.sworld.com.ua/konfer21/781.htm
http://crimso.msk.ru/Site/Arts/Art4478.htm
Last edited by RdsG; Nov 24, 2011 at 03:09 PM.
Nov 24, 2011, 03:31 PM
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hoverman's Avatar
Haha Yes, that is it! Strange looking craft, but it seems to be of the same design as the model in the video you posted Furthermore there's not much... well.. I don't quite get the logic behind it. The rear wing is of small chord/large span, the front wing is specialised for Ram effect.. so I guess that's the main Stability design, the rear wing is much less influenced by it's flying heigth.

Marijn
Nov 24, 2011, 06:30 PM
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RdsG's Avatar
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I quickly built a glider with a small reversed delta front wing and a much bigger, higher aspect ratio rear wing with big, dihedral wingtip fins. Rear wing has only 3-3,5° AoA. CG is about half way between the wings. This is my first model that I didn't built at home. So I didn't had my usual tools etc. Its more primitive than usualy , but it seems work fine.

My theory about its stability: When the craft pitches up, the rear bigger wing generates bigger additional lift than the front wing, so it returns to its stable flying height. And/or those wintip fins acts as OGE stabilizers.

Gabriel

ps.: On the first pic it has square wing in front of reversed delta-like wing, on the second photo it has a delta wing-like thing. Stability concept No 3. : Normally both section of the front wing generates lift, but if the craft pitches up, the front section will blocking the reversed delta section, so the front wing loses lift. But most likely it is used only as a hydroski.
Its under-fuselage PAR system is also interesting. This WIG is a freak
Last edited by RdsG; Nov 24, 2011 at 07:46 PM.
Nov 24, 2011, 11:49 PM
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@hoverman: Bateleur is not a WIG for sure, but when flying above the field it seems to be about 1 chord above ground so not in strong GE but probably already influenced by GE. Beside, if it changes heights because of waves (and it really looks like it does on the video) there must be some GE involved. I'm no pilot and may be being able to be stable in weak GE is not that hard after all, I was just curious if there was something to learn from this one.

@armour: If you don't want CAA involved, I'm afraid you'll have to stick here and build a WIG (150ft limit!). Beside, your double delta Bixel WIG looks promising (much more than the original Bixel prototypes frankly), I'm just questionning everything twice because I'd like to see this work the first time (something that really looks good _and_ really fly good!). BTW, if you go for the thick body version, you should have a look at the way they implemented ducted fan at body height in the DONAR hovercraft. May be a bit tricky to carve in a small RC model but could be interesting in a bigger version to keep the noise down and limit the nose up trimming to compensate for thrust above wings. Apparently, the impact on drag (fan intake close to the body) was not that bad since the max. speed vs. weight vs. power is in the usual range on what you find in hovercrafts.

@Gabriel: The more pictures you find about this WIG, the more it looks like a FrankenWIG. They must have had "good stuff" in Russia in the 70s. Really curious, but not sure I would try to fly one!

As a side note, I said I'd love to find a free 3D CFD to simulate armour's DDB idea... I found one and apparently a really good one... but no, I won't simulate the DDB with it. I think it will take me years to understand how a real 3D CFD work. But if anyone more knowledgeable than me wants to try it, it's OpenFoam and it's free... but quite complicated.

Also, while on the opensource subject, someone is designing a Caspian Monster for FlightGear (a fairly good opensource flight simulator). I'm curious to see how FlightGear handles IGE flight simulation but it seems it could. Something to follow.
Nov 25, 2011, 05:35 AM
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RdsG's Avatar
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I've found more about Baikal-2/M-6:

Irkutsk Polytechnical Institute (IPI) M-6 (mid-1990s)

(from Russian's ekranoplans -Red Star)
Nov 25, 2011, 06:52 AM
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Vykhan,

That Donar hovercraft looks good! I like the transmission system - props and inverted V rudders, I've toyed with that idea for a long time, especially as elevons combining yaw roll and pitch.

In fact with props at the nose roll yaw and pitch with V canards would do the same thing and coupled with an inverted V in the rear would be...
for example on a little Cessna 152, full throttle on the brakes and full up elevator, release brakes and wham! Tail strike!
With the cg far back(delta with long enough forebody) you could probably lift the nose right out of the water at start of take off roll, great for controll taking off in big waves!

More crazy ideas I guess!
Nov 25, 2011, 07:44 AM
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man i love those vides, perfect, i google a lot about Ekranoplan russian project and i found this Ekranoplan wiki page
Nov 25, 2011, 08:54 PM
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RdsG's Avatar
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I took a few "good" photos of the canard glider. On the third pic (I hope) you can see CG range marked with a pen. Interestingly it had no tendency to flip at all. After wind or something else forces it out of ground effect, it just returns to the ground smoothly. I am sure those big winglets makes it really stable. More testing is needed...

Gabriel
Nov 25, 2011, 09:08 PM
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@armour: I suggested to look at the Donar more for the duct fans implementation since, at first, I didn't like the idea of vectored thrust (if the engine fail, you're in trouble for landing without control surface). But I really like that idea of taking off under full power, full up elevator, some kind of STO(not-L) WIG and, after all, a well designed WIG should land safely without any control input. Besides, I believe the obvious engine for a WIG would be a Diesel engine: more efficient, heavier but not significantly compared to the max. gross weight of a WIG, not as reliable as an airplane engine but crash landing a WIG shouldn't result in a crash. And a Diesel engine is not very efficient at full power, so you'd probably use an engine that has ample power reserve... which could be used for your full power, full up elevator take-off. Not that crazy of an idea after all (since water brakes - air brakes in water - are as feasible as brakes on a regular airplane)... Wait, a WIG is not supposed to have elevators except for trimming the Cg position... but cheating is allowed in WIGs, right?
Last edited by Vykhan; Nov 25, 2011 at 09:36 PM.
Nov 25, 2011, 09:32 PM
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@Gabriel: This glider is really interesting: stable with all wings IGE. I'd be curious to see how it would behave with a longer chord on rear wings (to gain some IGE height)... or even a Bixel with a Lippish canard (Now, we're really talking FrankenWIG) although if the rear wings have a longer chord, the small chord Lippish canard won't be IGE at the height the rear wings will still be IGE and may not work as well, but who knows?
Nov 26, 2011, 06:52 AM
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RdsG's Avatar
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Quote:
Originally Posted by Vykhan
@Gabriel: This glider is really interesting: stable with all wings IGE.
Not exactly. As I said big winglets are like OGE stabilizer. They are also used for elevator trim. At first I wanted to use a separate stabilizer, but winglets also make it more efficient.

Gabriel
Last edited by RdsG; Nov 26, 2011 at 07:46 AM.


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