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Old Jul 31, 2010, 12:47 PM
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Okay, well maybe you can get wire at a local school? In most schools these resistance wires are used in physics experiments(measuring resistance of a wire blabla). This is how I got a few meters in several thicknesses.

Another option would be that you would look for some depron? This is often used as a dampoing material under wooden floors, is is also used in painting businesses. Further, in Paint/hobby shops one can often buy large plates of "Foamboard?" I believe it was called like that. It is similar to depron, but it is sandwiched between two layers of thin cardboard. It is light and very stiff, ideal for simple WIG models.

I'll be going on a 2 weeks vacation tomorrow, so I'll probably be less active in the forum

Keep up the building

Greetz, Marijn
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Old Jul 31, 2010, 02:13 PM
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if the foam between two layers of cardboard in Spain known as ``cartón pluma´´.
now that you told me just to remember my time in warhammer use to create buildings etc ... I think that where they sell on the thread I found a craft store where I Poer manager told me that in 1 week will.
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Old Jul 31, 2010, 02:55 PM
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Enjoy your vacation Marijn!


My next model will be a PAR WIG with a Lippisch type wing like the Chinese XTW WIGs:

XTW-1
XTW-2

XTW-3:
http://www.se-technology.com/wig/htm...code=&craft=93

XTW-4 (it has 20 seats!)
http://www.se-technology.com/wig/htm...code=&craft=94

XTW-5

http://www.krs.co.kr/kor/html/webzin...5B1%5D.ppt.pdf
page 96-100

Gabriel
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Old Aug 01, 2010, 08:30 AM
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Quote:
Originally Posted by RdsG View Post
Enjoy your vacation Marijn!


My next model will be a PAR WIG with a Lippisch type wing like the Chinese XTW WIGs:

XTW-1
XTW-2

XTW-3:
http://www.se-technology.com/wig/htm...code=&craft=93

XTW-4 (it has 20 seats!)
http://www.se-technology.com/wig/htm...code=&craft=94

XTW-5

http://www.krs.co.kr/kor/html/webzin...5B1%5D.ppt.pdf
page 96-100

Gabriel
ps: ...or an Universal Hovercraft tw-1 like thing...
http://www.hovercraft.com/content/in...ndex&cPath=174

sorry, i didn't want to send an other reply just edit :/
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Old Aug 02, 2010, 01:57 PM
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Hey!

I started to built my next WIG. Wings and the body are drying now.




... and a high res. photo of the XTW-5:



Gabriel
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Old Aug 02, 2010, 03:09 PM
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it looks good, but the engine in this position will make flying out of it?

what program you used to design it?

good luck
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Old Aug 02, 2010, 03:18 PM
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Hey Gabriel,

It looks very interesting and I am really wondering if you will have pitching problems when increasing or decreasing throttle! If you don't, this system will be perfect. I think I am going to try a similar setup soon, but on a squared ram wing(but this time without movable PAR motors).

Nice picture of the Japanese craft, there are several pictures of these crafts on the WIG page too. Btw, as you have probably noticed, these WIGs dont have upwards pointing PAR engines. Till now, I have seen other people resolving the resulting pitch down after throttling down, on models with upwards pointing PAR engines, by adding a small canard wing below the nose. Once the throttle is reduced, it pitches down, the canard wing is pushed into strong ground effect and keeps the nose up.

Anyway, looks promising, maybe this model will be a very slow flyer

And I'm enjoying my vacation, big pool and a lot of sun in the middle of France!

Greetz,

Marijn
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Old Aug 02, 2010, 03:25 PM
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Thanks. Perhaps I will reduce the angle of the motor with 5°, but this high angle needed to protect the prop and the motor from possible damage, and to produce enough air injection in the same time. Perhaps it will reduce air flow separation over the wing too. And of course I will be consider it when I set the CG.

I use SolidWorks to design my models.

Gabriel
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Old Aug 02, 2010, 04:20 PM
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Hey Marijn,

As I said this motor angle is a compromise between safe prop clearance, model size and optimal air injection. "Normal" motor angle would be better like the Chinese XTWs' have (not Japanese), but my props, motor size and aimed model size don't allow that configuration.

"Problem" is a relative term I will have pitch problems after a certain speed, but I hope it will have a speed range where it will be fly slow and stable (like the Flatwing).
Pitch down after throttle reduction/cut is actually useful in the streets since slowing down, or stopping should be fast.

The other problem is slow speed turning, mainly on the ground, since prop wash won't have an effect on the rudder. Perhaps I will make a small retractable wheel or something like this.

Enjoy your vacation!

Gabriel
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Old Aug 03, 2010, 01:07 PM
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Ahwell, wouldn't be modelbuilding without trial&error Looking forward to some pictures of the model!

Greetz from the pool

Marijn
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Old Aug 04, 2010, 03:55 PM
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I have an interesting problem with the model. I put on the motor temporarly for some ground tests. I held the tail of the model, and gave throttle. The motor had an angle to right to eliminate prop torque, so the left wing had more air injection, than the right wing. So I thought the model will turn to the right. But no, the model turned left and not just a little bit (I held the tail). Then I put the whole motor mount to the left with 3 mm. It still turned left. I tried to put the rest of the electronics to one side, and then to the other, but nothing changed... Perhaps one-prop air injection is not a good idea.

Slow speed turning is still a problem.

Perhaps I will leave air injection. It will be still "experimetal", since it has higher aspect ratio, high AoA wing with smaller wing area.
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Old Aug 05, 2010, 04:55 AM
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Hmm, before getting rid of the PAR idea completely, you could also try to place two small fins behind the prop in the prop wash, both with a sufficient deflection to counteract the roll(like putting two small ailerons behind the prop)

Marijn
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Old Aug 05, 2010, 05:45 AM
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I also wanted to add a "shark-like" rudder behind the prop, but first I want to add a steerable motor mount. So trimming, and turning would be solved.

Unfortunately these high AoA wings won't work without PAR... So I have to solve this problem.

Gabriel
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Old Aug 05, 2010, 06:41 AM
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I believe that:
if the motor rotates in clockwise direction, will make the model rotate in counterclockwise direction tore lengthwise, this causes the left wing touching the ground with more force, in theory should be offset by the extra injection of air, but I see no.

I would make a bigger model and put a motor on each wing.


if you wonder why your model is wrong and that of marjin not also deve marjin that the greater use of a prop smaller compared with the model, so the rotation length is much smaller.

for a small model so the prop is too big for what I see in the picture (only seen a little of the prop)


Correct me if I'm wrong.


Jorge
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Old Aug 05, 2010, 04:35 PM
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I tested the model, and it didn't worked , but...

So this air injection thing works, but this is the problem. At low speeds the main wing able to lift off, but the stabilizer at low speeds don't do anything.
The other big problem is that the single prop makes the air injection asymmetric. The air behind the prop is spiral shaped, and it makes the whole thing complicated, and unstable.
As Jorge mentioned, two counter rotating prop on each wing could solve this problem. But I don't have smaller power system, and a bigger model would be problematic on our street.

The good thing is that my steerable motor mount worked great. I just simply glued the motor mount on the top of the servo arm.

Gabriel
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