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Old Apr 12, 2008, 05:16 PM
Ozzie Express wiggy pilot
SON OF PALEFACE's Avatar
YANKALILLA , SOUTH AUSTRALIA.
Joined Nov 2002
5,234 Posts
Removing the canards is going to change the lift profile of the plane and this is not a good idea , this will change the area forward and require a shift of the cg rearwards....think of it this way if you INCREASED the size of the canards to double = more area forward , the cg would have to be moved forward other wise it would be a tail heavy situation with that extra lift from the extra forward area...I wont go into the center of pressure travel for different airfoils and plan view shapes
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Old Apr 12, 2008, 05:52 PM
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Quote:
Originally Posted by SON OF PALEFACE
Removing the canards is going to change the lift profile of the plane and this is not a good idea , this will change the area forward and require a shift of the cg rearwards....think of it this way if you INCREASED the size of the canards to double = more area forward , the cg would have to be moved forward other wise it would be a tail heavy situation with that extra lift from the extra forward area...I wont go into the center of pressure travel for different airfoils and plan view shapes
In theory.
In reality, those canards will have a negligible effect, at best, on lift. They will have an effect on trim, though.
They are tiny in relation to the wings.
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Old Apr 12, 2008, 06:16 PM
Ozzie Express wiggy pilot
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YANKALILLA , SOUTH AUSTRALIA.
Joined Nov 2002
5,234 Posts
Wrong... the canards have around 24 square inches area , you wouldnt take that much area OFF the front of the wing would you....even the fuse, forward of the cg creates some lift

However its your plane..............................
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Old Apr 12, 2008, 07:04 PM
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Sure you could.
Like I said, I doubt if they have anything but the most neligible effect on lift, and that's not why they are there. I have had delta models with canards, and took the canards right off, with negligible trim effect.
Anyway...if the guy decides to try it, we will see.
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Old Apr 12, 2008, 07:32 PM
Ozzie Express wiggy pilot
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YANKALILLA , SOUTH AUSTRALIA.
Joined Nov 2002
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like I said......its your model
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Old Apr 12, 2008, 10:25 PM
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USA, TX, Canyon Lake
Joined Jul 2006
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Well, it was way to windy today to try anything. Tommorrow it is supposed to be as well, but I am going to the flying field anyway to mow, so maybe I will try.

It isn't going to be practical to remove the canards anyway, they are installed in a permanent way.

I appreciate all the suggestions, but my inclination is to move the cg furthur forward a little at a time. and perhaps disable the mix to the canards and bring them to the nuetral position as indicated my the molding on the fuselage. However, If it won't rotate I will have to crank back in some mix.

Just to clarify how I am mixing, the canards are locked together, only one servo is moving them. I am not mixing elevon, I am mixing "elevator stick"
they simply act as an elevator, and the control surfaces on the wings are acting as elevons.

If I can fly it tommorow i will post the results.
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Old Apr 12, 2008, 11:04 PM
Team EJF >>>WHOOSH>>>
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Richard has the right idea.

Mixing Canards to Elevons really isnt such an oddball mix at all. To put it into a more 'conventional' perspective, it's practically the same concept as mixing Flaps to Elevator. The canards are coupled to the elevons, however they only move when a pitch command is given.

Removing the canards wouldn't be wise at all...
As mentioned earlier, they provide a significant amount of area and are located at a pretty good arm/moment from the CG. Removing the canards all together would change the aircraft's actual CG placement, kill alot of the lift the canard is producing, and you'd have to go back to finding the right CG.

Disabling the canard mix is a good way to go however... Im almost through building a J10 using elevons only, no canards at all, and it should do just fine.

Question for those of you flying this plane EDF:
Are you guys using any sort of intake ducting? Or just gluing the halves together?

Happy Flying,
Victor
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Old Apr 13, 2008, 05:40 AM
Ozzie Express wiggy pilot
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YANKALILLA , SOUTH AUSTRALIA.
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way to go Richard.....
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Old Apr 13, 2008, 08:16 PM
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USA, TX, Canyon Lake
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I did get a chance to fly it today, but it was insanely windy. With the headwind, it wasn't hard to rotate even though I have moved the CG a little bit forward. I'm still using the mix with the canards so far. With the wind the way it was I couldn't really draw any conclusions other than the CG change didn't hurt any.
On landing one of the little plastic "hub caps" that keep the wheels on came off and the wheel left the gear. No damage, but I couldn't find the hub cap. probably a good idea to glue then on.
I'll have to improvise to fix it, but It eliminated the chance for any additional flights today.

Richard
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Old Apr 13, 2008, 08:55 PM
Team EJF >>>WHOOSH>>>
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Whoops, I hate it when that happens!

Richard, does your J10 have any sort of intake ducting?
Or did you just glue the halves together?

Vic
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Old Apr 14, 2008, 12:00 PM
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United Kingdom, England, Carlisle
Joined Mar 2007
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I have discovered that canard trim on the GWS J-10 is quite critical, if it's too "down" it flies like the C of G is way forward, but if you actually watch it in flight, the elevators are working fine, you are just struggling like nuts to keep the nose up.
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Old Apr 14, 2008, 01:31 PM
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USA, TX, Canyon Lake
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No, I just put the two halves together, couldn't find any way to duct it.
I know, it defies all laws of good edf design, long torturous intake air path, but maybe it is because the fan is so good that it works!.
I understand that the GWS J10 has a cheater hole. I thought about trying that, but It doesn't seem to need it.

Richard




Quote:
Originally Posted by AceMigKiller
Whoops, I hate it when that happens!

Richard, does your J10 have any sort of intake ducting?
Or did you just glue the halves together?

Vic
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Old Apr 14, 2008, 02:33 PM
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Cool thanks,
I was kind of skeptical at first about just gluing the halves together, however they do pretty much form the sort of intake ducting im looking for... A little dirty, but not bad.
Still, im Taping wires the side and lining the inside with clear packing tape to keep things nice and as smooth as possible.

Regards,
Vic
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Old Apr 14, 2008, 02:48 PM
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Quote:
Originally Posted by doppler1
In theory.
In reality, those canards will have a negligible effect, at best, on lift. They will have an effect on trim, though.
They are tiny in relation to the wings.

The Canard is essentially an inverse-elevator mounted
near the nose. If you want the nose to go up (pitch up), tilt
your canards to a higher angle of attack, and they generate
lift and push the nose up. They can also be tilted down to
pull the nose down. Many modern canard airplanes can tilt
one canard up and one canard down, for roll (more lift on one side,
less lift on the other).

Some planes have non-moving canards just to generate lift
near the front, or for more lift during landing. These canards
are not used in maneuvering the plane, they just provide
more lift at high angles of attack, and better balance.
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Old Apr 14, 2008, 07:40 PM
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USA, TX, Canyon Lake
Joined Jul 2006
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I was afraid of tape coming off and getting sucked into the fan. I just used a hot glue gun to glue the wires to the side of the duct.


Quote:
Originally Posted by AceMigKiller
Cool thanks,
I was kind of skeptical at first about just gluing the halves together, however they do pretty much form the sort of intake ducting im looking for... A little dirty, but not bad.
Still, im Taping wires the side and lining the inside with clear packing tape to keep things nice and as smooth as possible.

Regards,
Vic
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