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Old Feb 23, 2013, 03:49 AM
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Quote:
Originally Posted by Captain Canardly View Post
UFFDA That Lockheed looks challenging! apair of 90's is sure gonna haul the mail! Have you looked @ the disk areas conversations @ EDF?
The fuselage area was "bumped" out 0.5 " to fit the 70mm fans. If I used 90s then the plane would have to be enlarged.
My SU-37 has two 70mm fans with ARC 36-75-1 motors and 100 amp esc. One fan produced over 4.5 lbs so this setup should work fine in the L-133
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Old Feb 23, 2013, 08:28 AM
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That fuselage will have some effects in pitch, something like adding some extra canard area. It may alter the required C/G, and will probably also delay canard stall a little. OTOH, the cross-section shape should reduce the nose's effect on yaw.
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Old Feb 24, 2013, 07:02 AM
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It looks great but have you assessed it for yaw stability - or lack of?
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Old Feb 24, 2013, 07:29 AM
Lighting Up the Darkness
United States, GA, Loganville
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Thanks Trevorh. No, I have not. What are your thoughts regarding yaw stability?
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Old Feb 24, 2013, 08:39 AM
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With the tip fins on the canard, I frankly don't rate your chances very high. Without them, it may be okay but could still be marginal. You have to remember that those fins aren't very far behind the cg compared with a conventional plane, so they really need to be proportionately bigger. Hopefully Don will chime in with a better qualified assessment.
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Old Feb 24, 2013, 08:46 AM
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I'd say Trevor covered it pretty well. It should be very good at flying sideways and maybe backwards.

Dihedral in the canard doesn't help, but those canard tip fins are especially bad (I would ditch those IMMEDIATELY, before first flight!), The steerable nosewheel will want to act like a rudder on the nose (more rudder authority, but less yaw stability), but the open-spoke wheel will probably keep that effect to a minimum. Lots of things along the stick fuselage that add side area (particularly the canard mount, the camera could also be a bad actor), and most of those are in front of the C/G. The pusher prop at the back will help add a little yaw stability, but probably not enough to fix the problem, sort of like putting a band aid on a lacerated artery. The fins on the wing are too close to the C/G to be enough help, but the drag of the wing in a severe yaw might help resist getting completely sideways.

A lot depends on the C/G location, but there are limits on just how far you can go with that. Even within those limits, the farther forward the C/G, the more weight will be carried by the canard, which will hurt efficiency and performance. A far enough forward C/G will cause the canard to stall (or at least run out of elevator authority, due to either stall of the elevators themselves, or insufficient elevator travel) before it can lift the nose, making it impossible to rotate for liftoff.

Apart from their very bad effects on yaw stability, the end plates on the canard may alter the canard's stall characteristics a little, delaying the stall a small amount (with the risk of making the wing stall first, although other things, particularly C/G, also influence that), and making the canard stall more abrupt when it does occur, resulting in a more violent pitch-down. None of that is particularly desirable.

OTOH, they do look cool, at least on the ground. They make the front end look a bit like the front wing on some race cars. Of course race cars are not particularly noted for their flying abilities
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Old Feb 24, 2013, 09:35 PM
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nightlightrepair

I heard the first rule of canards is that the forewing must stall before the main wing.

I think that refers to not only a pitch stall, but a yaw stall.

I think your forewing vert's have to smaller than those on the main wing, but why have them at all?

My only experience has been with a Shinden whose front fuse portion was larger than the fins and it got blown into a yaw stall
(see you tube "shin den maiden at tick point" )
I added vert stabs at the tips and that eliminated the yaw stall since they overcame the fat fusey's vertical surfaces.
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Old Feb 24, 2013, 09:47 PM
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You shouldn't have anything getting near a stall in yaw. The yaw stability and damping should be positive enough that things never get that far out of hand in the first place.
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Old Feb 26, 2013, 12:28 AM
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Tick Point Slope site (5 min 42 sec)
Or "Canard Cam #2"

The video above was taken from my canard, sloping north of the Golden Gate Bridge. It flew much better with winglets that I added. It didn't yaw stall as it did in the earlier video I made of the maiden (shin den maiden at Tick Point)
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Old Feb 26, 2013, 07:13 AM
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Beautiful! What a lovely place to fly! Looked very stable, l call that a success. Though I still don't believe that yaw stall is something to worry about - as long as we can keep the pointy end at the front.

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Old Feb 26, 2013, 08:01 AM
Lighting Up the Darkness
United States, GA, Loganville
Joined Jan 2013
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Thanks guys for sharing your expertise and experience regarding yaw. I believe I'd better make some modifications.....or eliminate the canard fins altogether before the maiden flight. But, you're right Don, it sure has made for a sporty looking "vehicle" zipping around my driveway! I need zippy and stable in the AIR though.
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Old Feb 26, 2013, 08:49 AM
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Russ, Check post 15 which shows smaller canard fins. I used them because Andy Lennon figured they were good to eliminate tip vortices. Your rear fins should be adequate like mine were because our areas are the same.I am anxious to see your good results.

Don, his nose wheel should remain straight in flight since there is no rudder control.

Charles
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Old Feb 26, 2013, 08:57 AM
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Charles, it is steerable, check photo 2 on post 6873.
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Old Feb 26, 2013, 09:38 AM
Lighting Up the Darkness
United States, GA, Loganville
Joined Jan 2013
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Don, it is steerable, but I have used the rudder stick to steer. Since there is no rudder, there will be no change in flight. The only operation of the steerable nose wheel will be on the ground.

Charles, good thing for the extended rain here in the Atlanta area - will give me time to contemplate and ponder prior to the maiden!

Video outcome will post on first pretty day! Thanks y'all
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