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Old Jun 26, 2010, 04:16 PM
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Thank you for the spec.!

It's smaller than I thought based on the photos At first 52g/dm^2 wing loading seemed too much... but it's a WIG, not an usual airplane.
But still it's more than twice as much as GM2's 19 g/dm^2.

Yesterday I also had an emergency landing. I think wind lifted up the nose, and it left the ground effect zone and started to fly in high alpha. Fortunately it happened relatively slowly. I had time to cut off throttle, and give full throttle again just before touch down. Finally it had no damage at all.

I flew in wind, I tried narrow turnings, and I tried what happens if it jumps on a bump. And happened "nothing" (except that case I mentioned above, but it happened just once)

Today I made an "edited" video. My brother and my sister and her boyfriend helped recording it. Mainly they watch the traffic

Ground effect flying with GM2 ekranoplan (0 min 53 sec)


Gabriel
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Old Jun 27, 2010, 07:22 AM
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Looks great!

Judging from the amount of power your setup gives you, it should be quite easy to build a 1.5 sized version of your bixel, with the same electronics. Maybe, this vast increase of wing surface, compared to only a minor increase in weight(just a bit more depron) will give you much slower and higher flying characteristics.

Are you planning any other wing planforms etc, or is this succesfull model the end of your ground effect build?

Marijn
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Old Jun 27, 2010, 08:17 AM
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Thanks!

I think this amount of power is just enough. I use only nimh batteries from the beginning. So this ~80 watt is reachable only when the battery fresh charged and cool.
I considering building a bigger one, but I afraid lighter wing loading makes it less resistant to wind. But at first I want to improve its turning ability when its taxing. Its rudder very effective while its flying or at higher speed taxing, but not when I just want to turn around. So I want to solve this problem. Then perhaps I add an air brake.

Then I don't know. It just works as good as I ever wanted.

It's not depron. It's made out of laminated floor underlay called Iso Floor It's very popular among model builders in Hungary.

Gabriel
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Old Jun 27, 2010, 03:59 PM
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OKay nice! You're probably right about decreasing the wing loading further, it won't improve the wind resistance at all. Looks like your posts on the Wig group caused quite a discussion haha.

Next weekend I'll try to make videos of the Lippisch, I hope the succes of last saturday wasn't a coincidence and I'll be able to reproduce it I have been thinking about why the craft crashed, durign take off it was perfectly stable, so the sponson design should be okay...right? I had the rudder and elevator on one stick, allthough I used to have ailerons on the rudder channel, I changed it after the crash. My guess is that I applied a lot of right rudder when I was only playing around with the elevator, which than caused the crash.

Ahwell, we will see!

Have you ever thought of building a Bixel to be used on water? It surelly complicates things, but it increases the thrill when the craft actually works and you can see the trail on the water dissappear

Marijn
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Old Jun 27, 2010, 04:47 PM
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I think there is no problem with your sponson design. Just one side reached the water earlier then the other due to too much rudder, or a wave... Good news is that you WIG is super stable in displacement mode since it didn't tip over.

Unfortunately models are not allowed on the lake nearby. On the other hand I can't afford loosing my electronics in a water crash landing. :/
It would be nice flying above the water, but flying past right next to your ankle has a thrill too
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Old Jun 28, 2010, 01:44 AM
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here some videos of my experimenting with this kind of stuff

http://www.rcgroups.com/forums/showp...6&postcount=10

EKRANOCAR for FPV (1 min 35 sec)


mad max hooverbiplane speed boat (0 min 26 sec)


fpv boat with Thomas' system, no salt water (3 min 6 sec)
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Old Jun 28, 2010, 12:15 PM
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Quote:
Originally Posted by David22 View Post
here some videos of my experimenting with this kind of stuff
Interesting, but I think it's not an ekranoplan (wing in ground effect craft). Ekranoplans are aircrafts and not boats. They fly close to a surface via ground effect.
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Old Jun 28, 2010, 05:25 PM
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Its kinda the same principle though.

If you look closely the cars wheels come off the ground a bit.

The boat however is heavy, but the ground effect still helps it be more efficient.

I can get that boat skimming over the water with 5 cells.

Here is a cool video

Ekranoplane (8 min 51 sec)
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Old Jun 29, 2010, 12:43 AM
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Cool that you have tested around with the ground effect, and you must be the first to have put wings on a car.

What RDsG meant, is that you are using two bent upwards wings, in a biplane configuration, mounted pretty high. Either you have discovered a new ground effect prinicple, otherwise I would say that you're wings don't use the ground effect at all
You have to be very close to the ground, preferably with a larger chord, to even sense a sort of Ram air effect. The only other part of ground effect you could get with those wings, is that the induced drag decreases as you're close to the surface, and even in that case, you're wingtips are located quite high, maybe the lower wing would profite just a bit, the upper wing absolutely doesn't.

Hey, no hard feelings, please post around you're ideas! But this is just not actual ground effect. You managed to lift of the boat or car, but my guess it is because you have two rather lare wings mounted ontop, instead of using Ground effect.

You can read this classic page, to see what we meant:
http://www.se-technology.com/wig/index.php

Cheers!

Marijn
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Old Jun 29, 2010, 12:48 AM
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no way man

once I get up to speed

it is ground effect for sure

even a regular plane as it lands has ground effect

skip to 2 min 30 sec in this video and it clearly shows ground effect with a regular plane

dlg with remote camera and transmitter systems testing, fly through football goal posts (3 min 14 sec)


skip to the landing here as well typical ground effect
end of video


Multiplex Easy Glider Pro on 4 cells (2 min 13 sec)
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Old Jun 29, 2010, 04:04 AM
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its true that traditional aircraft experience *some* ground effect, but the effects on traditional wings is far different than those on purpose built ekranoplans and WIGs.
a few of the WIGs in this thread operate on "ram air" effect which is like trapping air under the wing (much different ratios than normal plane wings). the ekranoplans can use both ram air and vortex reduction via surface effect to make them more efficient.
aircraft type wings were designed to operate in open air where the vortex needs to be reduced by changing the aspect ratio to lessen overall drag. this is one reason why ekranoplans do not perform well as an airplane, their wings were not designed to fly free from a surface. without this surface, the vortex would become MUCH greater and the drag on the wing is not good.

now i'm not saying that a normal wing wont work, its just that there is 40-50 some years of research as to the optimal wing type for a WIG or ekranoplan, and normal wings were found lacking in this application.

maybe try making some reverse delta wings for the boat or car
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Old Jun 29, 2010, 06:39 AM
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Did you heard about "Cushion Crow"?

All I know it is lifting body WIG model: (bottom of the page)
http://www.turkstra.com/K-Designs/WigFrame.htm
The whole body is a thick, low aspect ratio wing. Interesting idea.

Some time ago there was a page about it, but now it's offline.

But today I found interesting photos of a manned Cushion Crow on photopucket:

http://s393.photobucket.com/albums/p...t=frright2.jpg
http://s393.photobucket.com/albums/p...t=leftback.jpg



ps:

Some of the Jet Boats use very low aspect ratio, ground effect wings with huge side-plates to reduce hydrodynamic resistance by lifting the hull.

From 0:23:

Introduction to Whitewater Jet Boat Racing... (3 min 51 sec)
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Old Jun 29, 2010, 08:23 AM
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Here, I still had two pictures of the original Cusshioncrow on my harddisk. This guy also build a model with short stubby wings, with autogyro rotors on the end, a sort of WIG autogyro. I believe it didn't work too well, but the idea is cool.

I believe I have a video of it somewhere too...hmm



I wonder how the pitch stability is on this kind off "body". Eitherway, the full scale version looks hairraising!

btw, using wings is all that Hydroplanes do. They all have this ram wing cavity, but it offers stability similar to that of a Tandem. Everything is fine, till at a certain pitch up position it flips backwards very suddenly.
Budweiser tried around with other Ram wing configurations, to be able to unstick further without flipping. Here you can see a sort of Lippisch front wing with a tandem behind it.


Marijn
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Old Jun 29, 2010, 09:20 AM
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By the way, as it's a general Ekranoplan topic now, I scanned in a few pages from an old German Hobby magazin. It features a building description and plan for a sort of Lippisch WIG. The guy sais he saw the X-113 on tv and wanted to build a model. My guess is that he failed to realise that the principle of the Lippisch wig is that the whole trailing edge is rather parallel to the water, to probide a Ram wing cavity.

On this design the wings aere more airplane like, this should however mean that the pitching moments are much less noticable, so I think this model is an easy flyer





Lateron, somebody else designed another Lippisch model in Germany, called the "El Draco". It's a shame there is nearly nothing to be found of this model anymore on the internet, I believe it was introduced in the FMT-Extra Nr16 Magazine. Here is the original photo:

This one too, doesn't seem to be designed to provide a real cavity, which reduces lift, but makes this one also an easy flyer.
The original(I believe) is now standing proudly in the Merseburg Technik Museum in Germany, next to the Airfish 2 from Fischer Flugmechanik. Pitty the museum doesn't offer any information about both these items on the internet.



Just posting some Wig model history

Marijn
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Old Jun 29, 2010, 01:51 PM
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Hi

Great pictures/photos! Thanks!
Please upload the Cushion Crow video, if you have time.

I found an ekranoplan design/building contest I hope they will publish pictures, and videos.
http://www.etsin.upm.es/ETSINavales/...0009c7648aRCRD

Gabriel
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