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Old Apr 01, 2011, 01:59 AM
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Inari, Nice looking canard!
The landing gear looks well forward so I'm wondering how the CG was set.

Your Stealthsky fighter reminds me of the Firebolt 444. See the video here.
http://www.youtube.com/watch?v=VfAq40QGsxw

I think the forward sweep on the Firebolt design was probably intended to improve the lift distribution, but I'm still a bit doubtful about the benefits.
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Old Apr 01, 2011, 10:15 AM
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waw...excellent work, wery nice planes, I would like to recommed to use one of my stickers. All my planes got it. Good luck
Old Apr 01, 2011, 10:25 AM
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Inari, Thanks for showing the Stealthsky Fighter.

John 235, The Firebolt 444 was fun to watch and seems super stable. The canard elevator control was excellent even at slow speed. We need lots more
videos like that one.
Charles
Old Apr 04, 2011, 12:12 PM
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Goose Twin Update


A chuck glider was built with the canard at 3 degrees incidence and the wing at zero. It did not do well probably due to the large canard area and the high angle of attack. The glide was unstable and when thrown hard it would always yaw hard left as if to spin. The canard incidence was reduced by half to 1.5 degrees which improved the glide but was still yawing left. BTW, the span is 14 and the length is 15 inches. The canard area was reduced by cutting 1/4" from it's trailing edge and some weight was removed from the nose to maintain balance. It still has yaw problems but the glide was improved.
Area will now be added to the tail. Comments are welcome.
Charles
Last edited by canard addict; Apr 05, 2011 at 11:00 AM.
Old Apr 04, 2011, 03:31 PM
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Charles,
You asked for comments. Well I looked at your chuck glider a couple of times. You said that the area would be added to the tail. That is what struck me the most. While I haven't done anything close to what you are building and creating, it looks to me that the rudder needs to be bigger by about 20% or there about. Just my eye telling me that, I have no idea if that will help or hurt, but might add a bit of stability to the airframe since it wants to roll left.
Now I have no, not one bit of math or anything to back up my observation, just my eye that says it.
Conehead
Orrin Eldred
Old Apr 04, 2011, 04:48 PM
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I'd say it looks like too much vertical surface in front of the cg. I had this problem with a flying wing and it took big winglets to get yaw stability.
Old Apr 04, 2011, 05:16 PM
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Thanks for the Firebolt video. I wonder when the plans came out for that one? Definitely some similarities witht the Stealthsky Fighter.
Old Apr 04, 2011, 05:35 PM
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Conehead Orrin\
Quote:
You asked for comments. Well I looked at your chuck glider a couple of times. You said that the area would be added to the tail. That is what struck me the most. While I haven't done anything close to what you are building and creating, it looks to me that the rudder needs to be bigger by about 20% or there about. Just my eye telling me that, I have no idea if that will help or hurt, but might add a bit of stability to the airframe since it wants to roll left.
Now I have no, not one bit of math or anything to back up my observation, just my eye that says it.
Conehead
Orrin, I know that you are great with details and I appreciate your opinion.
The rudder was enlarged about 1/2 inch top and rear. It did make a difference
in the slow toss. Since the winds are 15 to 20 now, it is hard to judge how it compares to a previous good design.

Idriveaboxster
Quote:
I'd say it looks like too much vertical surface in front of the cg. I had this problem with a flying wing and it took big wing-lets to get yaw stability.
Thanks IDB, Do you mean that the fuselage needs to be trimmed off at the bottom? Note the vertical CG. I could add some medium wing lets to the wing tips to see if it stabilizes on a fast toss.
Old Apr 04, 2011, 08:23 PM
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I think, particularly with a flat fuselage chuck glider, the area in front of the cg is simply too large. I would suggest a longer moment or larger area on the vert. stab. Having a large tail is always good for slow flying stability. Also, maybe the main wing is interfering with the vert. stab. in high angles of attack. I'm not sure how you're testing this, so it's just some observations and ideas.

Paul
Old Apr 04, 2011, 09:45 PM
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Idriveaboxster Paul
Quote:
I would suggest a longer moment or larger area on the vert. stab. Having a large tail is always good for slow flying stability. Also
Paul, The CG is at the mid point of the fuselage so that all controls will have lots of leverage. I now believe that the problem was that the large mass of the rear wing and the tail being well behind the CG caused the glider to perform a maneuver like a ground loop in the air. It definitely needed more rudder to prevent the flat rotation.

The canard are has been reduced by nearly 20 square inches making it 51% of the main wing. The distance between the leading edges of the wings is now at 21.75 inches or 2.4 chords. Thanks to all for the helpful suggestions.
I expect the glider to perform well now in calm wind.

Charles
Old Apr 04, 2011, 11:04 PM
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I got you Charles on the wind problem. This morning it was very windy here, then the evening, none, now blowing like mad.
Rudder looks much better, in my opinion, so you will find out more when the wind settles down.
Conehead
Orrin Eldred
Old Apr 07, 2011, 11:52 AM
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I posted in Scale Electric as well but was referred here, so it is not spam cross posting. https://www.rcgroups.com/forums/show....php?t=1419470

I am a first time canard pilot but with many years of conventional plane experience. I have a 57” Long-EZ 46 with Axi 2826-12 motor on 6s and a 10x5 prop. I set the CG to 152mm from main wing LE as per manual and it flew terrible. I had to give almost full UP elevator just to keep it level and the plane oscillated from side to side. When I slowed it down, it would go in a stall spin and the only way to get it out of the spin was to give full power and fly it out of the spin. Therefore I could not slow it down for the landing and had to fly it in at more than half power. If I did not have the power I had available, surely this plane was back in “kit form”. I know it is a CG problem but do not have any previous canard experience to know where to set it. I downloaded the canard CG calculator as directed in the other thread and the CG calculated to almost the same position as the manual indicated.

I decided to move the CG backward by about 20mm and flew again. It improved a little bit but it still required a lot of up elevator and stall if slow down. I moved the CG backward even more but did not get the change to fly again. On the take-off run the main undercarriage ripped out of the fuselage and need to be repaired first before I can try again. Also the prop broke. So much for ARF quality. (I am mainly a scratch builder.)
Also, the manual indicated that the engine / motor should be square to the firewall, but it is obvious it need up thrust. On the second flight, when closing the throttle it would immediately lift its nose before slowing down. I did not recognize this on the first flight as I was too busy just keeping it in the air, very “interesting” flight, “best” I had in years.

Please, before I fly (and crash) this thing again, help me in the correct direction to do a propper setup.
Old Apr 07, 2011, 12:30 PM
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Rebell! Howdy and welcome to Canards!
I would start with a full inspection of the wing angles- the way the spins were defined, seems there's some skootching needed (somewhere) if you could take a couple pics for (me)us, that will help. we need the canard viewed from side with flight description at (that) angle, and Would need a perpendicular shot - E- "top View'-of the craft total (i don;t have any data for Vari EZE's in my CAD). and we'll start there.
Johnny
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Last edited by Captain Canardly; Apr 07, 2011 at 12:31 PM. Reason: "top view" added
Old Apr 07, 2011, 12:59 PM
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It is this plane. This is a picture I saved from RCG.

I will take some pictures over the weekend.

I just checked, the UC hardly had any glue on it and was depended on very thin ply for its strength.
Old Apr 07, 2011, 01:42 PM
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Hi Rebell!

Sorry to hear about your interesting flight. I agree with Johnny. With all the canards I've flown, the thrust line and incidence of the wings and canard are crucial. With the Long EZ, all are in the same line, so they all need to be at zero (except... see below). The C G calculator has always been about spot on. I use it with the static margin at 10% and this usually moves your C G forward enough to load the canard correctly. Consequently, you can add about 2 degrees of incidence to the canard, it should be carrying more weight per area than the main wing.

But that's a minor change that can be adjusted via the trim, it shouldn't cause the panic you described. I flew my Starship the other day with the CG 25 mm too far forward. Found myself pulling the elevator all the way back nearly all the time, but I still got round alright and landed safely. A much more frightening flight was when I flew it with the C G 25mm too far back. Even so, as long as I kept the nose down I got home alright. WS is 60" and AUW is about 3 lbs, I think.

I hope that's helpful, the other guys on here will give you good advice. This thread is the sole source of all I know. Good luck!

Nick