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Old Aug 20, 2010, 06:21 AM
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Haha I am looking forward to testing this monster too David! First...painting

I really wonder how this thing works, IF it works. It looks like it isn't gonna work at all, on the other side I can't find a single detail which..would confirm that it will probably fail

Marijn
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Old Aug 20, 2010, 07:41 AM
BEOWULF
North vancouver, B.C. Canada
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don't helli propellers need clean air below them to work properly, ie the wing will block the wind and be pushed down counter acting the ekranoplan ground effect idea?
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Old Aug 20, 2010, 01:07 PM
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Looking cool!

Regarding autogyros, My friend had a large Kellet, and it was a nightmare of sorts to fly. It really could have used cyclic big time! Would have been much much better flyer with.
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Old Aug 20, 2010, 03:37 PM
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Quote:
Originally Posted by hoverman View Post
Haha I am looking forward to testing this monster too David! First...painting

I really wonder how this thing works, IF it works. It looks like it isn't gonna work at all, on the other side I can't find a single detail which..would confirm that it will probably fail

Marijn
And what color will it be?
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Old Aug 21, 2010, 05:46 AM
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@ David, You are absolutely right, but that is also one of the reason why this model isn't made to hover. It will apply positive collective pitch once a certain forward speed is achieved, which results in a backwards downwash from the rotor, not a completelly vertical downstream, thus clearing the largest part of the wing. We also placed the rotor quite high, to give more space between the rotor disc and the Bixel wing.

@ Silenthunter, okay, that has been clarified then

@ Gabriel, at the moment I am going for plain white, the model is complicated enough by it's shape, I thought wild colours would make it worse

Marijn
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Old Aug 24, 2010, 12:28 PM
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Hey Guys,

What happened to all the projects, Whizzywigs. tandems etc

Yesterday I finally met Luc de Keyser, the Heliferry is his brainchild. We talked a while about the concept, hydrodynamic unstick problems, and also other concepts, and how WIG projects in Europa rise and fail all the time. Further the progress on the Heliferry model is now:

It has been painted, is smooth and totally white. Further, the mount for the heliframe has been thickened, the rudder servo and pushrods have been installed, the motor mount has been finished, two small aluminium water rudders have been added, and the stabiliser has been reinforced. It really starts to come together! I also ordered some spare parts for the heli, and the propulsion motor for the prop, together with servos for the swash.

Enough about the Heliferry, I found some nice artist scetches of 2nd generation WIG's. After his initial rather crude straight RAM wing designs, Alexeyev attempted to build more aerodynamically efficient WIG's. One of the resulting SM test vehicles resembled this:


But he tried to improve the results even further, by designing a flying wing WIG. Some of his testing results can vbe found, with resulting L/D ratios, depending on the usage of wing fences or round sponsons etc.:





It looks cool, but nomatter how hard they tried, they never got around all the pitching problems, and went back to a sort of compromise layout, a flying wing vehicle with Aspect Ratios of around 5, but also featuring a small T tail. Following the testing, another 1:1 SM test vehicle was build, of which no photo's are known to exist, and after testing the craft was immediatelly destroyed
Might be interesting to play around with?

Anyway, I was in the progress of designing a PAR Wig model, here's one of the drawings:


Greetz,

Marijn
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Last edited by hoverman; Aug 24, 2010 at 12:33 PM.
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Old Aug 24, 2010, 05:38 PM
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looks good but it seems rare as a flying wing wig, the AIRCAT about this, tomorrow we will be able to fly, now is getting stuck, now I have servo extension cords and a good horn.

test it tomorrow.
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Old Aug 24, 2010, 10:12 PM
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Other wig designs

This is a great thread.

Here are two unique wig layouts that I've always wanted try to build RC models of.

Harry Schoell’s Canard flarecraft (patent 5,566,775)

http://www.schoellmarine.com/flarecraft/flarecraft.htm

A.I. Pietsukh’s PAI-67 (Diamond winged, tandem, and Lippisch Reverse Delta!)

http://brunodemichelis.com/Images/Russia39.gif
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Old Aug 25, 2010, 12:22 PM
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Hey Nbrophy, I actually have a photo of a craft somewhere which is very similar to that diamant shape you showed, I'll see if I can find it.

Anyway, I was trying to figure out if the T-shape of the Bixel shape really helps against pitching problems. As I was reading through Bixel's story again, I noticed that he talks about how great flat profiles are blabla, but there's not much to be found about why he chose this strange wing shape(only that it damps out rolling in sharp turns).

Another thing, russian and chinese Type A WIG's have flat and slightly S curved profiles, and only small stabilisers, & no outboard wings.

And..another thing, the Bixel wing shape works in both directions!

Now a thought came up, maybe this T-shape doesn't really add very much to the pitch stability at all, and these Bixels mostly fly great because of the used profiles.

Souns interesting, lets test it

Two models, both same wing chords, spans and angles, same stabiliser profiles, sizes and angles. One with a square flat wing, the other one with a Bixel shaped flat wing.

A bit of throwing around to detirmine the CG positions..


Ofcourse, the Bixel shape results in a more backwards CG position, as it's CP is also more rearward due too the outboard wings:


And, also some tests without stabiliser and the CG at the position as stated by Bixel himself:


Results? Actually, the Square winged WIG is the best one! It's the one with the fewest pitch changes, and the highest stable flying height. Both the square, as the Bixel don't flip under any circumstance, even when they are thrown out of GE(they pitch down, instead of up)

Now..I am not entirely convinced yet..but it seems as though a flat square wing works just great, as lon as the stabiliser/CG angle/position is right.

I compared this square wing WIG to the Lippisch model I was so enthousiastic about a while ago, and it looks like this square one works even better! Windgusts, hitting rocks, throwing it upwards, or throwing it into the street, it always seems to recover nicely

And again.. a whole lot of writing about some small pieces of foam

From left to right, best to worst: 1 - 4 - 2 - 6 - 5 - 3





Marijn
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Old Aug 25, 2010, 02:40 PM
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So simple is better = square flat-wing

Harry Schoell’s Canard flarecraft is also very interesting. Two months ago I built a simple, small tandem lippisch glider. It worked pretty good, but later I just forgot the idea. It looked very similar to Schoell’s Canard wig.

Gabriel
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Old Aug 25, 2010, 02:51 PM
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For those interested in the Canard, you could read through this:

http://www.freepatentsonline.com/5314035.pdf

And

http://www.freepatentsonline.com/5566775.pdf

There's lots of interesting things to be found in these patent pages, for example this:

http://www.freepatentsonline.com/3908783.pdf

Which is the patent from Jörg, and confirms my theory that the rear wing on a Tandem wig is supposed to be less dependant on GE as the front wing

You can also find the patent description of the Lippisch reversed delta etc.

Marijn
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Old Aug 25, 2010, 04:52 PM
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Marijn,
I start in a few weeks a special Taxiboat project on the Maldives. It is a boat. But for the next step I will built a WIG for there islands. Maybe you must come with me....

Achim
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Old Aug 26, 2010, 04:39 AM
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Hey Achim, sounds interesting, what kind of boating service are you guys planning to build up? And don't forget, I am trying to completely figure out all the principles and techniques of WIG vehicles, but I can't confirm my theory's mathematically in any way, it's all just..trying to prove it by using small models.

Something else, My guess is that Bixel uses the T wing for only one purpose, to dampen roll movements. So yes, for his flat wing principle to work you can use a square wing, but it doesn't have to mean that is is better all the way...just simpler

Marijn
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Old Aug 26, 2010, 08:05 AM
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so, the T shape keeps her stable in the turns, but the square one may show some undesirable roll issues...

my question, were the square wing and bixel wing models the same area and weight? (wing loading)
that could effect it quite a bit as well i'm sure
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Old Aug 26, 2010, 06:09 PM
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Nicely noticed Derk, indeed the wing area of the T shaped model is a bit smaller. I compensated this by increasing the sponson size on the other model, as I was expecting a more forward CG anyway. I don't know if it's exactly the same, but I am pretty sure that you won't notice this difference on such rugged models

Now I don't think it's really rolling problems that this square wing has, it's more..it doesn't roll at all. it behaves like a Type A wig, flying close to the ground, always wings level, even with gusts. If it banks anyway, sure the T-wing will recover better

I just found it 'interesting' that you don't need this T-shape at all, for a pitch stable model. Most first WIG models are square wing models, which by bad balance and wrong stabiliser angles tend to fly very bad, or not even fly at all. Then they find the Bixel story, build a T-wing and are convinced that it is briliant, and forget about the square wing at all(I had the same thing). Now I am starting to realise that the succes of the models build following the Bixel story, comes from the fact that they use flat profiles and very long wing chords(increasing the CP movements of the wing).

So if you encounter pitch problems with a square wing, it isn't to blame on the wing shape, the problem will mostly lie in bad CG positions and stabiliser sizer/angles.

Marijn

Marijn
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