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Old Jun 21, 2012, 09:17 PM
OY-5542
Chrizz's Avatar
Denmark, Central Denmark Region, Silkeborg
Joined Nov 2009
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Yet-to-be-named KFM Canard... or is it a DSW with rudder and fuselage?..

Hi Everybody!

I'm in the process of making an ultra micro canard and it would be great to get your opinions on what I've been planning so far!
So, please, comment, criticize and come with your ideas!

It's intended for an AR6400, one or two AS2000 and the prop/gear/motor from a Sukhoi Xp.
I'm planning to set the plane up, for the canard to only serve as elevator and the wing's ailerons only as such (though it's an interesting idea to have ailevons, why not coupled to the canard!?...) The ailerons will be full span, both on the main wing and the canard. To that I'll ad a rudder situated below the wing.

Here is what I've drawn so far:
Name: KFM Canard - 3 view.png
Views: 96
Size: 26.0 KB
Description: Exploded 3 view - without landinggear (yet to be drawn...) Name: KFM Canard - Exploded 3 view.png
Views: 86
Size: 35.2 KB
Description: 3 view - without landinggear (yet to be drawn...)
Notice that there are two possible wings drawn on the 3 view.

I'm also planning to make an undercarriage (take-off's, touch-an-go's and landings are to delightful to dispence of).
First I thought I would make a tricycle-type landinggear, but realized I could make use of the rudder being placed below the wing, well in line with the fuselage, to make a steerable tailwheel. So now I'm planning to make a classical landinggear with a steerable tailwheel for better taxiing. I'll make drawings of it soon.

Hope you guys like it! ...?

Happy landings ;-)
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Old Jun 21, 2012, 09:31 PM
OY-5542
Chrizz's Avatar
Denmark, Central Denmark Region, Silkeborg
Joined Nov 2009
731 Posts
...the difficult thing, when drawing a landinggear, is when you don't know how to calculate the CG...



Any ideas about CG and canards???
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Old Jun 21, 2012, 10:41 PM
"Unnecessary Necessity"
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Canada, BC, Vancouver
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From an old post!
http://www.rcgroups.com/forums/showp...02&postcount=1
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Old Jun 21, 2012, 11:21 PM
OY-5542
Chrizz's Avatar
Denmark, Central Denmark Region, Silkeborg
Joined Nov 2009
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Thanks coriolan!

I'll study that thread, it seems great.

Meanwhile I've made a sketch:
Name: KFM Canard - 3 view with classic landinggear.png
Views: 83
Size: 24.2 KB
Description:

Bare in mind that I have no concrete knowledge to base this drawing of a possible landinggear... Yet! :-)
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Old Jun 21, 2012, 11:47 PM
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Just use tricycle landing gear! Put two wheels under the wings, and one in the nose. Your prop is high enough, just make it so there's enough ground clearance at the proper takeoff AOA.
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Old Jun 22, 2012, 05:43 AM
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Kokomo, Indiana
Joined Jun 2008
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My blog on my Ember 2 Canard may be of help, also. Learned much reconfiguring the airframe. Presently flying well with the pusher-motor thrust angle parrallel with the CF fuselage on all directions. The CG is just behind the leading edge of the main wing. Around this location is where canards want to be for stable pitch. Please keep reporting as you develop your design.

Curt
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Old Jun 22, 2012, 08:44 AM
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Blacksburg, VA 24060 USA
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It may be possible to eliminate the landing gear and skid the airplane on its belly for take-off. The propeller is high enough on the fuselage not to strike the floor, and you may have enough elevator authority (on the canard) to lift the nose and get some air under the wings.

Jim R.
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Old Jun 22, 2012, 09:03 AM
OY-5542
Chrizz's Avatar
Denmark, Central Denmark Region, Silkeborg
Joined Nov 2009
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Hi! Thank you guys for your responce and suggestions!

I was thinking of just using a tricycle and it's still a solution, but I came to realize that I want to make use of the rudder for a steerable tailwheel (beside the looks of it, I like it very much, it's a nice feature to have).

About prop clearing, while making these drawings I recalled the looks of another, older projects of mine (in fact some of the first pieces of foam I've had put together). The fuselage, hanging under the wing, allowed for enough prop-clearance to taxi around even without any undercarriage. I fough of drawing something similar, but didn't want to push the design in to much in that direction (it's quite similar already).
Name: 3.jpg
Views: 99
Size: 168.1 KB
Description: 'Le Bleu'. One of my first "scratch-bilds". It had a landinggear, but was more than able to taxi/takeof/land without.

Thank you CorvetteC5 for your suggestions. I'll probably calculate the CG precisely thanks to coriolan's link, but still have to study the subject yet!
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Old Jun 22, 2012, 09:45 AM
Lookin' up at the centerline
taildragger1589's Avatar
Lawrenceville, Georgia
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Quote:
Originally Posted by Chrizz View Post
I was thinking of just using a tricycle and it's still a solution, but I came to realize that I want to make use of the rudder for a steerable tailwheel
Good going! there are enough nose draggers around!
my canard wasn't one.
BTW, the cg on mine only had a 1/2" envelope.

Nick
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Old Jun 22, 2012, 12:52 PM
OY-5542
Chrizz's Avatar
Denmark, Central Denmark Region, Silkeborg
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Quote:
Originally Posted by coriolan View Post
THANK YOU SO MUCH!!! Great CG calculator, just what I needed!

:-)
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Old Jun 22, 2012, 09:21 PM
Mack
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Australia, VIC, Mentone
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You may already be aware of this thread, Chris, but anyway:
http://www.rcgroups.com/forums/showthread.php?t=613556
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Old Jun 22, 2012, 10:42 PM
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Westlake Village CA
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Hi

Here's a nice interactive Canard CG calculator.http://adamone.rchomepage.com/cg_canard.htm
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Old Jun 22, 2012, 10:55 PM
OY-5542
Chrizz's Avatar
Denmark, Central Denmark Region, Silkeborg
Joined Nov 2009
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Thanks a lot for the links!

For now, I've been having some fun with the CG calculator coriolan linked.
It's great fun and very practical (it's the first time I get myself involved with a CG calculator and the way this one works, seems to make for a good introduction. It is very complete with many options available).
A very recommendable tool!

BTW: The CG calculator's results indicates that my current layout might end up nose-heavy.
I fed the calculator with; the exact wing/canard/fuselage design; every component (electronics, prop/gear/motor, lipo, torsionbars), their exact weight and location in the airframe. But I have not entered any data concerning the wing/canard/fuselage's weights (didn't want to start calculating their wheigh, to lasy tonight to even estimate...). With the airframe probably being nose-heavy on its own, that data will probably not help solve the equation.
Then I simulated a counter-ballast and found (on basis of the above described preliminary calculation) that 4,18g added weight to the very rear of the envelope, would correct the CG!

I also am tempted to make a forward swept wing, so I made a drawing:
Name: KFM Canard - 3 view Forward Swept Wing.png
Views: 177
Size: 22.7 KB
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It might contribute to get the CG right without theaid of ballast.
I'm just not sure I want to make a forward swept wing, adding another source for complications. The canard might be challenging enough for a start...
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Old Jun 23, 2012, 08:56 AM
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taildragger1589,

That is a terrific Pico J-3 Cub Stick Canard! How well does it fly? Where did you locate the CG, and how did you do it?

I made a free-flight canard airplane 25 years ago, but it was a bear to adjust, so I abandoned the idea. A hard landing wiped out the canard, so I abandoned the project.

Jim R.
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Old Jun 23, 2012, 12:39 PM
Lookin' up at the centerline
taildragger1589's Avatar
Lawrenceville, Georgia
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Well, I'm sorry to say that it flew, but not very well.
My first mistake was to have the canard at only 4 degrees, I started at 2 and it took 45 degress of down elevator to fly level, so I added a shim.
The cg was about 3/4" ahead of leading edge and if moved more than 1/4" either way, it went unstable.
Part of the problem (I think) was the motor on a pylon. I could tell it pulled the nose down when throttle increased.
I had the pylon screwed to the fuselage with one screw so I could adjust upthrust, but never got enough to counter the nose down tendancy.
Finally, when the wings kept slipping out of the sockets, I retired it since it could only fly around at half throttle.
Good points: the rudder was very effective and the landing gear worked great.
what it needed most was to have the motor on the tail or nose.
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