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Old Apr 05, 2012, 10:57 AM
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A bit more done and some more pictures.
The first pictures show what slowed me down lately; I took my time to airbrush an old GWS Zero I refurbished during the past winter.
Then the other shots show the wing and tailplane covered with polyspan and sealed with two coats of acrylic dope. Just on the top of the tailplane I applied a sheet of checkered esaky paper.
Last pictures show the installation of the ailerons to the wing. With a small brush I coat the pintle of the hinges with melted bee wax and then I epoxy the ailerons in place. When the glue sets, it's easy to remove the wax with a scalpel and have free movement. I wash the brush with nitrate dope thinner.
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Old Apr 05, 2012, 02:08 PM
Visitor from Reality
United States, VA, Arlington
Joined Dec 1996
12,788 Posts
Hi Guizzo
Your rudder operation is interesting. Certainly will be light and should work fine. Many years ago, I designed and built a shoulder winged sports aerobatic model with twin fins and rudders. Used a bellcrank in a rather thick symmetrical sectioned tailplane to operate pushrods that ran out through the fins just ahead of the tailplane trailing edge. Control horns cut from 'paxolin' sheet - did I mention this was a while ago? - came out of the rudders' outside faces and curved back to pick up the pushrods.

This was somewhat tricky to design and build - no CAD to work out shapes and relative movements, of course - but worked well. My biggest worry was that the rudders were pretty much outside of the propwash from up front but the model never gave any problems on take off. It was a taildragger too.

Your outwards only rudders should be fine for the way this model is intended to fly, and you have a light control system as well.

Nice paint job on the Zero too - love the pilot's armband! It's a good looking aircraft and should fly real well.

Regards

Dereck
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Old Apr 06, 2012, 05:05 PM
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very kind of you,Dereck! I appreciate.
I previously used a similar setup on the Linnet I built a couple of years ago; you may see what I did here, but Im close to install the control linkage to the rudders and I guess that next week I may post same pictures.


I couldn't resist to put all the pieces together! There's still quite a lot to do but the end is close enough!
I glued the elevator servo on his bed and linked the elevator with a Y pushrod. The electrical connector allow length registration of the pushrod that I'll substitute with a tin soldering after test flights.
The rudder simply can't rotate inside, it may only bend outwards and the torque bar returns it centered.
A happy Easter to you all!
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Old Apr 11, 2012, 05:02 PM
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This is the last thing I've done. The stabilizer now is held in place with two nylon bolt which allow to reduce the incidence of the stabilizer just changing the shape of the stabilizer saddle. As I stated in the first post of this thread, the stabilizer has 5 incidence, good for a rubber powered model but I guess a bit too much for an electric motor. Flight tests will say if Im right or wrong.
The links 1 and 2 are for a two short videos (beg your pardon but I don't know how to join them in a single one and get rid of the noise!) they show how my rudders work, the movement to the rudders is via a steel braided self sealing fish-line. I'm pretty satisfied for what I have done but now Im facing problems with the ailerons servos, I need to change them because they wobble! I also destroyed a 2S lipo pack I left connected to the receiver while setting up the control trows!
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Old Apr 27, 2012, 01:29 AM
I like real wooden aeroplanes!
Sundancer's Avatar
South-west France
Joined Sep 2007
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Lovely job Guizzo. Best of luck with the first flights.
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Old Apr 27, 2012, 09:40 AM
Use your imagination....
czirh's Avatar
Turkey, Izmir, Seferihisar
Joined Oct 2007
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Beautiful...

Cem
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Old May 01, 2012, 12:23 PM
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Thanks Sundancerall and czirh!
Unluckily, the maiden was not successful!
I first taxied the model along the grass strip to see how she would behave and once I saw she was running smooth and straight, I made a second run increasing the power a bit farther than half throttle with the intention to have a short leap in the air.
As soon as I reached a sufficient speed I applied a gentle pressure to the elevator stick and the nose of the model abruptly arose vertically and I had my canard keeled over her back in no time and without lifting off the ground one inch!
Luckily the model suffered no damage but a rudder wing tip unstuck.
I'm quite sure the problem is the elevator set at an excessive incidence (+5);
Other possible problems may be:
- wrong C.G. position (I'll check it again)
- insufficient down-thrust (very unlikely considering I set the motor at 0 and the
model looped at half throttle!)
- nose landing gear leg too short with consequent 1.5 negative asset of the
fuselage (but both wing and elevator have positive incidence!).
Anyhow, before making changes, I'll ask advices to more competent modeler in the canard forum and, of course, from you all!
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Old May 01, 2012, 04:00 PM
Lookin' up at the centerline
taildragger1589's Avatar
Lawrenceville, Georgia
Joined Feb 2005
2,404 Posts
Really looking forward to seeing your solution.
I've been playing around with canards and like yourself, don't know a whole lot of whys. but if this helps...
My cubnard wouldn't fly if the canard was less than 5 degrees. I started out with 2 degrees and could not get a cg to work with it, either it dove into the ground or flipped over backwards as you described, all with a cg inside a 1/2" range.
As I added incidence the range got bigger, until finally I got to 5 degrees and it flew somewhat normally with the cg 1/2" ahead of the wing LE.
good luck!

Nick
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Old May 02, 2012, 09:39 AM
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Thanks Nick, I really appreciate!
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Old May 03, 2012, 07:30 AM
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It seems to me that the canard wing on Guizzo's model is the dominant force and the rear wing stalled before it could gain enough speed to fly. Five degrees up front is, IMO, too much for a 57% canard. My current model under construction has a 50% canard and the angular difference between the two wings is three degrees. I am a bit nervous about it's design. If there is too much drag from the grass, a canard model will suddenly break loose from the ground with UP elevator applied which will not be good if equilibrium is not attained. Smooth ground surface helps when testing. Also, the rear landing gear must be positioned behind the CG for easy rotation without excessive lift from the canard wing. You have a beautiful model, Guizzo! I hope that my views will help you decide how to make it fly.

Charles
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Old May 04, 2012, 04:14 PM
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Thanks Charles, your help is most regarded!
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Old May 05, 2012, 01:56 AM
Just Me
United States, OR, Salem
Joined Apr 2006
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Hi Guizzo,

Very nice work and beautiful model. Your thread here peaked my interest in trying my hand at a Canard (my first attempt at same) and I happened to have the plans for the Cunny. Please don't confuse me with the experts that post their knowledge on here. I am most certainly a complete newbie with respect to Canards.

To the point....I first built up a little chuck glider (WS=18") using the Cunny plans as a guide. Set the wing (flat plate for now) at 1 degree positive and the canard at 4 degrees positive. I set the cg according to the online calculator. Although mine was powered by "arm", I got much the same results as you describe, although mine never flipped completely over (guess my arm just isn't what it use to be....lol). The nose would elevate immediately and stall the wing. It would not recover from this.

I had no idea what to modify so I just jumped on the next version, another chuck glider (little larger WS=24"). Reduced the size of the Canard (this was just a guess on my part). As this one wouldn't be a "Cunny", I made a couple of small design changes as indicated on the attached jpg. AOA on both wing and Canard remained the same as the first glider. This one flies straight line fine although I have no idea what it might do under real power.

I do believe that Charles has identified the problem and that the original Cunny's Canard is overpowering the wing. Although I'm not sure I attacked that problem the correct way.

I'm aiming for about 36-40" WS (electric pusher) final but I'd appreciate any comments from you and/or the others on here as to whether I'm headed in the right direction.
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Last edited by Brner; May 05, 2012 at 01:15 PM. Reason: spelling....
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Old May 05, 2012, 11:41 AM
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Bmer,You are definitely on the right track. Your second glider is proportioned well and should fly. For more stability you could increase the fuselage of the glider 2 by about 3 inches and not bother with dihedral on the powered version. Chuck glider one might have done better with more load on the canard to enhance the stall before the main wing. I hope that Guzzio approves of our sideline discussion on his thread.

Charles
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Old May 05, 2012, 01:16 PM
Just Me
United States, OR, Salem
Joined Apr 2006
855 Posts
Hi Charles....Certainly didn't mean to hijack his thread but his initial post is what got me started on this learning experience. His was/is a beautiful model.

I hope this input will be of some use to him in resolving his problem with the Cunny.
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