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Old Jul 18, 2010, 07:28 AM
IAD
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New England, USA
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I suppose I should wait to find out if it was a radio issue, but just in case it wasn't... What sort of airfoils did you use? If the main wings are flat-bottomed or semi-symmetric, and the canards are symmetric, if the canards are at 0 deg. incidence (or even slightly positive) it is possible that you'll have pitch stability issues...

The basic idea behind canard stability is that the canard's coefficient of lift (CL) must be greater than the wing's CL, in order for the system to generate the corrective reactions to pitch disturbances. For instance, at 0 deg. AOA, an undercambered airfoil may already have a CL of 0.25+, while a symmetric section will have a CL of 0... Thus, for a hypothetical canard airframe with 0 deg. incidence, using the symmetric section on the main wing, and the undercambered section on the canard would result in a stable airframe, while swapping the airfoils would result in an unstable airframe. (Assuming you place the CG so that the main wing is the primary lifting surface.)

Even identical sections on both the canards and main wings (with 0 deg. incidence) may still get you in trouble, since the narrower-chord canards will generally operate at lower efficiency, resulting in the CLwing > CLcanard case... This depends greatly on the particular airfoil you use, and just how small/thin the canards are, though.

Anyway, sorry about the long post, but in a nutshell, 0 deg. is (in most cases) fine for flat-plate wings-canard arrangements, but when using airfoils, setting the canards at +2-5 deg. incidence relative to the wings never hurt...

~Luke
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Old Jul 26, 2010, 11:35 PM
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So the torsion bar setup I used for the canard appears to be using too thin of wire. The wire twists and allows the canard to straighten out, or even point slightly downward, with a very small amount of pressure. That's not to say that there were not aerodynamic issues as well, but it appears that this explains the reason the nose dropped and didn't respond at all to full up elevator
An awful lot of work to go down the tubes because of a little piece of wire...
I am thinking I will glue it back together (won't be as pretty) and replace the wire with some much thicker guage and see where that puts me...
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Last edited by jon6foot4; Jul 26, 2010 at 11:39 PM. Reason: add pics
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Old Jul 29, 2010, 02:37 PM
I even seen a house fly!
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Montreal!
Joined Oct 2003
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Jon, she looks absolutely beautiful in those shots She NEEDS to fly! It would make me uber-happy to see her doing so!

Cheers and great work so far!

Kitty
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Old Jan 13, 2011, 01:06 AM
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Tampere, Finland
Joined Nov 2004
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I see the FRX-99 UCAV is coming along:

http://www.rcgroups.com/forums/showthread.php?t=1174936

90% done, 90% to go?

(and bump)
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Old Jan 13, 2011, 06:46 AM
IAD
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New England, USA
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Yes indeed. Over a year now! But, I think it's coming out pretty well, all things considered.

~Luke
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Old May 06, 2012, 03:34 AM
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Tampere, Finland
Joined Nov 2004
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This thread is ancient but I think it is good.

I don't have any flying models to contribute but, recently, I've been playing with Inkscape (a free vector graphics program) and making some What-If aircraft 3 views. So far, it is mainly modified versions of real life aircraft: F-18 XS Hornette and imaginary versions of the Spitfire. My "Serbian MiG 32" seems to be the only one that is only based on various pieces of speculative concept art.

I've posted them on deviantArt, which seems like a good place for such drawings.
http://perttime.deviantart.com/gallery/

Here's a couple of examples what I've got by now:
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Old Jul 24, 2012, 04:29 AM
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Seoul, South Korea
Joined Sep 2002
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Hello Guys.

http://home.att.net/~dannysoar/FantasySectionIntro.htm

What happened to the danny soar site?
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Old Jul 26, 2012, 07:04 AM
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Poland, Silesian Voivodeship, Tarnowskie Gory
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Disappeared from the net, probably. Here's archive:

http://web.archive.org/web/200812220...ctionIntro.htm
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Old Jul 26, 2012, 01:49 PM
An itch?. Scratch build.
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South Wales U.K.
Joined Mar 2003
13,393 Posts
Quote:
Originally Posted by jon6foot4 View Post
So the torsion bar setup I used for the canard appears to be using too thin of wire. The wire twists and allows the canard to straighten out, or even point slightly downward, with a very small amount of pressure. That's not to say that there were not aerodynamic issues as well, but it appears that this explains the reason the nose dropped and didn't respond at all to full up elevator
An awful lot of work to go down the tubes because of a little piece of wire...
I am thinking I will glue it back together (won't be as pretty) and replace the wire with some much thicker guage and see where that puts me...
But shouldn't there be another three motors as well ?
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Old Aug 19, 2012, 09:14 AM
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Seoul, South Korea
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Quote:
Originally Posted by MiQ27 View Post
Disappeared from the net, probably. Here's archive:

http://web.archive.org/web/200812220...ctionIntro.htm
Thanks MiQ27
You are my life saver.
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Old Oct 11, 2012, 01:35 AM
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South Africa, GP, Krugersdorp
Joined Jul 2012
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Subsribed
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Old Oct 11, 2012, 10:40 AM
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Tampere, Finland
Joined Nov 2004
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Things have been slow in this thread...

I'll post another picture that I've made recently. It is a fantasy interceptor based on the ill-fated Napier-Heston Racer.
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Old Oct 11, 2012, 09:18 PM
rab
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Arlington, Virginia
Joined Aug 2004
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I noticed this site recently: http://xplanes.tumblr.com/.

- Allen
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