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Old Oct 13, 2011, 02:25 PM
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Old Oct 13, 2011, 02:50 PM
space 1 is offline
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build test glide. may need canard's. I would just do necell on top
Old Oct 13, 2011, 04:03 PM
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Very cool looking bird!


Hi
It looks fast and exotic!

A few tricks of the trade regarding your configuration:
- Forward swept wing is good for preventing tip stall
- Stalling a section of the wing far back gives a nose up pitching moment, agrevating the stall (not so good)
- Strakes are good for maintaining a high energi flow over the root of a "strait" wing at high angles of attack (high alfa)
- Strakes moves the center of pressure forward (nose up moment) since they do not stall when the main wing does, this agrevates the stall further
- Strakes sometimes gives a high energy flow over the fins (or V-tail in your case) increasing efficiency of said fins

Shaping of this type of configuration for full scale aircraft takes hundreds of hours of wind tunnel tests.
However, this is done since pilots won't climb into an untested aircraft...

Aaaand, modellers don't have to bother with that apprehension so we just build and test fly!!!

If I where you I'd do a small balsa/depron free flyer to establish a safe CoG and size of tail planes. Go for it!!!

Best reagrds
Patrik
Old Oct 14, 2011, 02:32 AM
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mix

very cool design. I might suggest that you check out a few threads on this forum. there are two FSW projects underway and I think it would be wise to jump on board those threads to give you ideas for yours. I'm sure Steve and others will jump on board yoru tread to help you out.

one way to prevent nose up on deep stall is to add negative incidence to the root foil. another way, is to do what the full size planes do and use an airfoil that looks a lot like a thinner version of that used on the A-10. it's got a very definite undercamber to the rear of the foil, which brings the lift further back, thereby giving a pitch down in high alpha, deep stall conditions.

Rich
Old Oct 14, 2011, 02:42 AM
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Old Oct 14, 2011, 04:23 AM
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Old Oct 14, 2011, 04:25 AM
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Old Oct 14, 2011, 04:32 AM
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Old Oct 14, 2011, 06:11 AM
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build fly
Old Oct 14, 2011, 07:07 AM
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Mix, got your text. My design doesn't use any forward canard wings, no fuse lex.
After experimenting with a sfw layout I finally found the angle it needed to fly as a wing, not a whole plane. I added the fuse to it all later. I use a full elevon control surface now, my first design had separate Ali and ele, my second design used the elevon mix in the radio. I happen to balance at the hinge line at the tips in my designs now because of the swept forward angle. Canards and Lex's will throw another wrench into your CG so beware. I recommend building a chuck glider(small test airframe) to test your design and finalize the CG location then proceed to the actual design and build.
http://www.twitt.org/Cornelius02.gif my inspiration years ago
Old Oct 14, 2011, 09:42 AM
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Old Oct 14, 2011, 09:54 AM
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Old Oct 14, 2011, 01:49 PM
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I like your design, look very cool. I did a FSW last year and I used a small amount of wash in, seems to work with symmetrical naca airfoils. See https://www.rcgroups.com/forums/show....php?t=1202354

By the way is there any chance you will share your sketch up file, I am trying to learn to use it, maybe it can will help me if I can se how you done it.
Old Oct 14, 2011, 02:31 PM
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Old Oct 14, 2011, 07:05 PM
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deffinitely use carbon spars to alleviate twisting of the wings.

deffinitely use wash in at the root.

deffinitely keep the tip at zero degrees as per the thrust line of the plane, or close to it.

the whole idea of an FSW is that the tip does not stall and that the root remains flying as long as possible. when the root does stall, the tip should still remain flying becuse of its forward position and the way that lift travels down the wing towards the root.

LEX's are a good addition, since they will energize the flow over the root. however, they can make the plane very pitch sensitive. you may need a close coupled canard if you go with LEX's. as suggested, make chuck gliders with and with out the LEX's and see what works best. if the LEX's work best but you find it very pitchy, add canards and see if they elliminate the pitchy behaviour. if you look at the SU above and others such as the X-29, etc, they all have canards to counteract the LEX's. I personally think you should use the LEX's, but figure out how to make them work with the airframe, instead of against you while maneuvering the plane.

Rich


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