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Old Jul 27, 2010, 02:11 PM
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Originally Posted by jjjasesino View Post

hoverman, a few hours ago i make a quick and improvisedmodel and i put the hydrofoils to 1 cm of the hull and worked well in the aterrizage There was not any problem as well estava not only holds the hydrofoil and detached.
Have you got pictures? I can't really see it before me but it sounds cool!

Here, you can see how the high speed supercavitating foils were build on my model, as on this Robbe Skiboat. The foils are slightly curved on the model to provide better performance at lower speeds, but for higher speeds its terripble, so keep them flat! You'll need sharp leading edges, with blunt trailing edges, just like the rudders of high speed hyrdoplanes.


I also had this, it's not a WIG either, but just as interesting for WIG's, the Piaggio P.7. A Racer designed for the Schneider trophy, without floats. It has hydrofoils and at first, it accelerates using the water propeller, with the air propeller beeing feathered. Once it's foil born, the air propeller is clear of the water and the pilot changes the clutch do drive it, and continue the Take off.




There were actually some other planes, using hydrofoils or small hydroski's as a Take off aid:



Interesting right

Marijn
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Old Jul 27, 2010, 02:51 PM
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Originally Posted by hoverman View Post

BTW for all WIG enthousiasts, Graham Taylor updated his site, have a look:
http://www.grahamktaylor.com/models/...%20models.html

Greetz,

Marijn
Thanks Marijn,
I have an plan of the SEAWIND in scale 1:7.4
I am try to use maybe the hull from it.
Have you a idea how can I scal it from the drawing to 1:1 for a file to use it on a milling machine how cut me the bulkheads out?

Regards
Achim
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Old Jul 27, 2010, 03:17 PM
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My guess is, you have the FMT Seawind plan?(VTH Verlag) I don't know if you have a digital version of the plan, otherwise you could go to Multicopy, they are able to scan plans up to 1 meter wide. Then you could scale it up as much as you like in paint/photoshop etc.

Greetz,

Marijn
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Old Jul 27, 2010, 03:27 PM
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@hoverman: Thanks for the link!
@coast-flyer:
Bixel-type is very stable in strong ground effect zone but not as efficient as others. Lippisch-type is efficient, pretty stable, and it has big ground clearence but it's handling changes depends on speed. Jörg-type stable in strong GEZ, efficient, and could reach high speeds, but it has small ground clearance, and it can't operate out of GEZ. So every WIG has a balance between handling/stability, ground clearance and efficiency. Thats why I think you should build more than one model, you should find out which type (it could be a hybrid-type) is good for you.



I uploaded a compilation of Flatwing Lippisch onboard videos:

RC Lippisch-type WIG onboard (2 min 13 sec)


Gabriel
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Old Jul 27, 2010, 03:58 PM
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Originally Posted by hoverman View Post
My guess is, you have the FMT Seawind plan?(VTH Verlag)
Yes, from an old FMT, it's a print version.
To go in a copy shop.............no way. Need a programm file what I can use on a milling machine.

Achim
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Old Jul 27, 2010, 04:10 PM
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Hey Gabriel,

A cool video of your Lippisch model! I am amazed to see how...smooth it flies, and it actually isn't as fast as I thought(which is a good thing). Nice video

I also found some Tandem drawings, like this one:


And it looks futuristic, but still, it's a nice design.

Marijn
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Old Jul 27, 2010, 04:21 PM
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Have you got pictures? I can't really see it before me but it sounds cool!
no i don´t have any picture (my phone is being repaired because it got wet before I can make any photo), the model was a simple bixel with a 4 small hidrofoils, the hidrofoils have a 3cm wingspan and 4cm long.
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Old Jul 27, 2010, 05:21 PM
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Marijn, the new "wig shuttle" they want to fly 1.2 mtr. high.....

Achim
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Old Jul 27, 2010, 05:35 PM
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hmm, if a thick round leading edge helps prevent early separation, and a stall, how would you rate the flat plate wings?
if i could get away with a 6mm base and 2mm upper skin, it would be easy to build the wings since they wouldnt be one folded skin over ribs/spar.

Marijn, do you think the tandem would be ok with a semi-flat front wing and an airfoil rear wing?
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Old Jul 27, 2010, 05:50 PM
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Marijn, the new "wig shuttle" they want to fly 1.2 mtr. high.....

Achim
Interesting, but it's hard to believe that they will be able to achieve this ground clearance since the biggest Jörg tandem, TAF-VIII-4 (which is bigger than WIG Shuttle) has 0,53 m.

There is a Jörg design which is a 135-seated TAF. It is 45,6 x 16,6 x 9 m. It's planned ground clearance is 1,25 m.

@Marijn
: Thanks!

I tried to make jumps, but it was very instable out of ground effect. I think last time I was just lucky with that 70 cm jump :P The edge of GEZ is about 15-18 cm. 20-25 cm jump could be ok, but not recomended . I put the camera on the front, so the CG moved slightly forward. With this setting it could maintain 6-8 cm high stable flight.

Gabriel
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Old Jul 27, 2010, 08:01 PM
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well, not sure if it will work or not yet, but i'm nearly finished with my tandem WIG
weight should be around 4-5 oz (113 grams to 141 grams) rtf.
5 gram motor, 300mah 2s lipo, 1 4 gram servo and a gws pico rx.
mostly 6mm depron, with some 2 and 3mm mixed in. the front wing is a single piece of 6mm with camber formed into it, the rear wing is 6mm plate with 3 ribs and a top skin of 2mm. i tried to get the front wing to have a little more aoa than the rear one, so we'll see what happens.
run time should be around 6-8 minutes at full throttle so maybe longer if it doesnt need all that power.
will take some pics and post them in a few minutes.
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Old Jul 27, 2010, 08:14 PM
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i started with grey depron but thought it could get lost in the grey of the asphalt so added some white to help contrast.
i built in a mounting point for the camera just ahead of the c.g. so it shouldnt affect it too much.

first flight should be later tonight if i get enough done!
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Old Jul 27, 2010, 08:14 PM
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cool video
Quote:
Originally Posted by RdsG View Post
@hoverman: Thanks for the link!
@coast-flyer:
Bixel-type is very stable in strong ground effect zone but not as efficient as others. Lippisch-type is efficient, pretty stable, and it has big ground clearence but it's handling changes depends on speed. Jörg-type stable in strong GEZ, efficient, and could reach high speeds, but it has small ground clearance, and it can't operate out of GEZ. So every WIG has a balance between handling/stability, ground clearance and efficiency. Thats why I think you should build more than one model, you should find out which type (it could be a hybrid-type) is good for you.



I uploaded a compilation of Flatwing Lippisch onboard videos:

RC Lippisch-type WIG onboard (2 min 13 sec)

Gabriel
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Old Jul 27, 2010, 10:45 PM
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@ Derk - flat profiled front wings work great, if you curve them, even better! I believe that at least a part of the strong longitudinal stability of the tandem relies on the fact that the front wing has a high AoA and curved underside, to provide a lot of RAM air lift. The rear wing has a rather shallow angle of attack, a flat bottom and a véry thick profile. In this configuration, the rear wing is able to make quite some lift too, but it doesn't rely so much on the Ground effect.

If the craft increases it's flight altitude a bit, the strong RAM-air effect decreases quickly and the front wing will lose quite a lot of lift, allthough the rear wing won't notice this altitude change as much as the front wing and it will still provide most of it's lift. --> the craft tends to pitch down. If you add this to the fact that placing two wings in strong ground effect gives a very nice pitch damping, which gives the tandem this 'robust' flight handling, you'll get a very stable craft, as long as your close to the ground.

Anyway, the model looks cool, if it tends to flip, just shove the CG forward and forward till it stops, don't start cutting in the wings directly.

@ Gabriel, I found the Airfish to be quite stable, or at least very well controllable on pitch, everytime I accidentely flew it out of GE. It did however start to roll over everytime, because of the negative dihedral.

and how the **** they want to achieve 1,2 meters, I don't know. clearly, it is possible, as long as you stabilse it as a tandem winged airplane, not as a jörg boat. But then, if you're still able to fly it without elevator, I don't know

Marijn
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Old Jul 27, 2010, 11:09 PM
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well, just did the first test runs in the parking lot outside! it seemed that the rear was lifting higher than the front, so i moved the battery out of the nose and onto the front wing. this time ig glided more evenly but the batt must have shifted rear because as i slowed it down, it pitched up and stalled. so i re positioned the battery a little farther forward and it flew just right! although i must admit the cg is FAR rear from your models
turning control seems adequate as i was almost able to do a full lap around the cars and planters! it still however wanted to roll a little when turning tightly, but didnt flip or drag until it slowed down too much. i did get one short video which i will look over and put up later tonight.

i think i need to install my longer range Rx and make part of it up in a tube like on rc cars and boats. i was surprised the little motor could push this beast so well! it wont take off from a standstill, but with a little push, it gets right up in about 15 feet!

i still need to add the top to the fuselage and make a frontal hatch. i'll take some more pictures to show what the rudder assembly looks like and such.

Derrik
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