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Old Jul 19, 2010, 06:14 PM
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Gripen


I've been lurking here all along but not done anything with a Canard lately. Time to change that. Along with several other projects in the works I have been working on an EDF Gripen. Finally got started on the actual construction. This will be all laser cut Depron, mostly 6mm. Power will be a WeMo 50mm Microfan with a 6000kv HET inrunner on 3s. This combo has worked well for me in the past. Control will be elevon, rudder, throttle with the canard mixed to the elevator.

John
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Old Jul 19, 2010, 08:10 PM
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John, It's good to hear from you! Your models have always been great. Please continue to show this one.
Charles
Old Jul 20, 2010, 01:11 AM
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Sweet, today my package from Hobby King arrived. I bought six motors to experiment with and both 40 and 45mm spinners depending on how blocky my nacelles end up being.

Forgot to order my props somehow--must have gone to bed right before hitting the paypal button (damn cough syrup) so I've gotta wait a week for Tower to get my assortment of APC counter-rotating props out here (these are 9x6 and 10x6 respectively). Then some bench testing.

Carl
Old Jul 20, 2010, 02:15 AM
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Sketched in the main wing and while I'm not set on the planform it should be easy to build at 68". Six feet threw out the proportions of my concept sketch too much. Meh.
Old Jul 20, 2010, 04:24 AM
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Charles

In your Gooses (Geese?) what is the purpose for the small fins on the canards, is it aerodynamic or aesthetic?

Tony
Old Jul 20, 2010, 04:42 AM
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Hybrid structures


Floats for the EZyCat.

Here's my take on using a mixture of Depron and balsa in construction. Depron is good in compression, balsa and spruce are good in tension. some wooden spars or longerons might be good in John's Gripen. Tho' I have to say it looks pretty good anyway.

cheers

Nick
Last edited by nickchud; Jul 20, 2010 at 07:31 AM.
Old Jul 20, 2010, 07:23 AM
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Nick,

There is a carbon fiber tube spar in the wing and the axle for the canards is cf tube. The basic Depron fuselage structure has been used on many many models without the need of CF or balsa. Keeping it light is critical for EDF performance and flying is what it is all about :>) Thanks for the kind words guys and I will post more pics as progress happens.

John
Old Jul 20, 2010, 09:03 AM
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John

I'm sure you're right. It's the cantilever arrangement of my pylon structure that puts extra stress on things. There was someone here who was asking for a ready cut kit to build a canard recently. Is yours available as a kit?

Nick
Old Jul 20, 2010, 09:56 AM
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Nick,

If flight testing shows good performance I will make kits available. However if flight tests show poor performance this will not be the first project to be scraped.

John
Old Jul 20, 2010, 02:20 PM
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Perdu
Quote:
Charles

In your Gooses (Geese?) what is the purpose for the small fins on the canards, is it aerodynamic or aesthetic?

Tony
It's a little of both, Tony. There is a pressure difference between thr top and bottom surfaces which causes the air from below to swirl around the tip and join the air friom the top causing a vortice. The fin might prevent some of this and looks so good to me that they will become larger on my models. I figure that the fin action might even add some lateral stability especially in turns. The Evader has lots of fin action front to back and I love the way it flies.
Old Jul 20, 2010, 02:35 PM
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Tip vortice vs Winglets


Check here for an interesting discussion with pictures. My Goose design used winglets as Andy Lennon did on his Canada Goose.
Charles

http://en.wikipedia.org/wiki/Wingtip_device
Old Jul 21, 2010, 01:39 AM
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Alright fellow duck enthusiasts, I've got some major progress on my computer model to share. I swear that modeling fillets in Rhino is actually harder than taking the time to build them in the shop but I think I've gotten close enough for bulkhead profiles at this point.

Obviously still missing are the fins and pontoons, but it's getting close to slice-up time
Old Jul 21, 2010, 04:41 AM
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Charles

Thanks for the info. I'm learning a lot in this thread.
I like the look of your Evader and nice to see the article in Q&EFI.

Tony
Old Jul 21, 2010, 12:12 PM
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Learning by Doing


Perdu Tony
Quote:
Thanks for the info. I'm learning a lot in this thread.
I appreciate your kind words, Tony. In order to remain interested in our hobby,we must have a challenge. There are four projects happening now in our thread and each one is exercising the mind and learning is taking place. In the mid nineties, the hobby became stale to me because it seemed that I was standing still doing the same thing over and over. The switch to electric flight opened up a whole new and exciting effort. After ten years, a fellow club member brought a canard glider to the field and my interest in the new style caught fire. With a little balsa or foam and some clay for weight, you can make your own flying machine! So far all of my gliders have been scaled up to full sized models and all are flying well. The projects were presented here and as you can see, lots of discussion brought on lots of thinking and learning happened. Without progress, we soon lose interest. My belief is that the model world is the foundation of air progress. Rutan is a great example of that.
Charles
Old Jul 21, 2010, 02:07 PM
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Charles

My interest with canards started in the 80s I saw an article in radio model about a hang-glider canard so I tried to make one. It wasn't successful, I didn't know about canard aerodynamics, now I know the CG was at least 3" far back. I made it with ripstop nylon, aluminium, carbon tube and steel Pike trace for the bracing, noisy, no control after about 10 yd but the canard bug started.

Tony