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Old Feb 09, 2011, 12:35 PM
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Caish
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Your wingspan is wrong but I can work with the numbers.
Its going to be partial ugly stick wings, so they're bound in the middle. I haven't measured it but its going to be fairly short, 24 to 28" but still the full chord.
I'm thinking of a twin slightly V'd vertical stabs also.
How do they fly without a rudder just Aileron and Elevator?
I'll have to work on the light part a little, but it will still be very light. Hybrid foam fuselage, and balsa monokote covered wing.
Caish, I prefer longer wings but if you use almost square wing panels on each side, my senses tell me that the vertical stabs would work better being vertical and placed on the wing tips. Also with less wing area, you will need more speed unless the model is very light weight. Your model should fly well with ailerons and elevator but with the short span use 2 inch and full length strip ailerons. Adding rudder control seems like doing too much at one time to me. You may get a bit of lateral rocking with the short wing. The opinions of our experts would be helpful here. I use adequate power, a smooth surface and a great test pilot when in doubt of the model's performance. Once you learn how to make a canard come alive when leaving the ground, you will be in for lots of good future experiences.
Charles
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Old Feb 09, 2011, 03:19 PM
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Delta Duck 2 Details

John 235
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It looks like you did the right thing with the larger fin/rudder. Against the increased wingspan, I wouldn't have picked it as having been enlarged. More pictures would be very welcome.
Yesterday 11:32 PM
Hopefully these will show it better.
Charles
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Old Feb 09, 2011, 06:56 PM
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Now I see the extra fin area!

Thanks for the pics. It really highlights the changes. I am always interested to study your designs.

I hope the maiden flight goes uneventfully. I have confidence in your updated design, so I'm expecting a good outcome. Best of luck anyway.
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Old Feb 09, 2011, 08:03 PM
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Thank you, John, and I am always happy to share my methods, right, wrong or questionable.

Nichud, Trevorh
[QUOTE]
Quote:
Originally Posted by nickchud;17355801
"dynamic stability is linearly proportional to the area, but to the square of the moment arm."
Aha! the penny drops. I'll pay a lot more attention to lateral area in future.
[/QUOTE

I had a similar reaction. I'm now pretty well convinced that this is why the Each Way Bet wouldn't fly, but the Stanger biplane with similar dimensions was rock steady. The big difference between them (apart from weight) was the fuselage structure - open framework for the Stanger, vertical and horizontal Depron sheets for the EWB.
Trevor, Your four part description of the Each Way Bet was great reading. Please don't take this as flattery but the instant transformation of the model from conventional to canard was a reflection of mechanical, electrical and aeronautical genius. I could not follow it well but it worked like magic. The November video of the canard's flight looked like the rear wings stalled and the December flight wobbled as if the CG was too far back with alternate tip stalling. I would not attempt to disagree with your reasons for failure in part four because you certainly should know more about your creation than I do. Your presence here is greatly appreciated.
Charles
PS, Congratulations on the stable flight of the standard version.
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Old Feb 13, 2011, 01:24 AM
Flutter-Bys are fun
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I am at E-Fest and this fellow, I guess you say bloke, from England shows up again this year with is camera and taking pictures of everything, Dereck shows up again. I am not sure I got the right, or correct English word for him, but I could listen to him for hours. So if it is an insult, I am sorry. What a fellow. He sort of enjoys living in Chicago. I know this has nothing to do with canards, but Dereck was all over the Armory, I think he filled at least 2 memory cards up with pictures. Was a treat to see him again this year. I hoped he would bring something to fly.
Conehead
Orrin Eldred
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Old Feb 13, 2011, 09:30 AM
An itch?. Scratch build.
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Help with Canard CG please.

I am building a monster that stands a good chance of flying IF I get the CG something like right.

It's based on the MIG 1.42/1.44, (3-view below). Now it's not accurate, only based on the shape, but pretty close.

My dilemma regarding the CG is, do I take into account the fuselage ?, and if so, how much ?.

I have used the Canard CG Calculator, assuming 10% as a fairly safe margin.

BUT, depending on whether I just use the 'external' wing areas, or the projected areas into the fuselage center line, I get two CG locations.

Any advice would be welcome.
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Old Feb 13, 2011, 10:03 AM
Fly Lite Fly Right
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Hi Charles
Nice new design and love the lines .
Keep up the good work .
Your friend
Keith
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Old Feb 13, 2011, 11:51 AM
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eflightray
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My dilemma regarding the CG is, do I take into account the fuselage ?, and if so, how much ?.

I have used the Canard CG Calculator, assuming 10% as a fairly safe margin.
For a wide fuselage with stubby wings on a fast model, I would go along with the advice of Don Stackhouse and include the fuselage into the area. Ten percent static margin has worked well in this forum. The model, if set up that way, should be easily controllable. It looks like a stable design as I see it. Please let us know how it works out.

Happymcc
Quote:
Hi Charles
Nice new design and love the lines .
Thanks, Keith, I can hardly take my eyes off of it and may get to test it soon with mild weather approaching.

Conehead
Quote:
I am at E-Fest and this fellow, I guess you say bloke, from England shows up again this year with is camera and taking pictures of everything, Dereck shows up again. I am not sure I got the right, or correct English word for him, but I could listen to him for hours. So if it is an insult, I am sorry. What a fellow. He sort of enjoys living in Chicago. I know this has nothing to do with canards, but Dereck was all over the Armory, I think he filled at least 2 memory cards up with pictures. Was a treat to see him again this year. I hoped he would bring something to fly.
Conehead
Lucky you, Orrin, I have seen Dereck only twice and loved his enthusiasm.

Charles
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Old Feb 20, 2011, 06:36 PM
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Cressline Star Chaser canard

Anyone know the CG for the Cressline Star Chaser canard? It is the .46 ws60"
Thanks.
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Old Feb 20, 2011, 10:07 PM
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Star Chaser!

Hi,

I just happen to have one!

According to the plans and instructions book, the CG is at 3 1/2" to 4 1/2" in front of the leading edge at the fuse. Make sure you check it with a FULL fuel tank, as stated in the book.

Later!
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Old Feb 20, 2011, 11:05 PM
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Star Chaser Canard

There seems to be two versions of the Star Chaser. Go here to read details:

http://www.rcuniverse.com/forum/m_47...tm.htm#5000997

On one version the main wing is at zero incidence and the canard is at two degrees positive. The second version has a positive main wing incidence with a lesser angle on the canard. I feel that the CG positions would be different on the two and that the CG calculator would best work on the first version. edit: please read Don's comments on post 5067 following.
Get the calculator here:

http://adamone.rchomepage.com/cg_canard.htm

Can anyone show us a picture of the Star Chaser?

Charles
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Old Feb 21, 2011, 07:12 AM
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Quote:
Originally Posted by canard addict View Post
There seems to be two versions of the Star Chaser. Go here to read details:

http://www.rcuniverse.com/forum/m_47...tm.htm#5000997

On one version the main wing is at zero incidence and the canard is at two degrees positive. The second version has a positive main wing incidence with a lesser angle on the canard. I feel that the CG positions would be different on the two...
Sometimes I feel like I'm beating my head on a brick wall on this thread.

OK, one more time:

NO.

Incidence does not control C/G.

Let me repeat that:

Incidence does NOT control C/G !!!!!!!!

C/G controls stability. As long as the planforms, areas, moment arms, etc., are the same, C/G should be the same. On a canard in particular it also controls how much load is carried by the canard, and therefore whether the canard stalls before the wing (good), or vice versa (bad, probably very bad).

Note, the same relationship is true on a conventional layout, although by the time you make sure that stability concerns are met, you've already ensured that the forward flying surface (the wing in that case) stalls first (although there can and have been exceptions, such as the early Cessna Cardinals)

Incidence controls what angle the fuselage flies at when the wing is flying at the desired flying speed, and the wing angle of attack needed to support the plane at that airspeed.

Canard incidence determines what elevator deflection you need to keep the plane in trim at the desired airspeed.

If you try to use C/G location to control flight trim, you can quickly paint yourself into a corner where the plane has stability and control problems, including things like static divergence, and stalling the wing before the canard.
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Last edited by Don Stackhouse; Feb 21, 2011 at 07:19 AM.
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Old Feb 21, 2011, 10:33 AM
What could possibly go wrong?
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hmmmm
Quote:
(C/G) also controls how much load is carried by the canard
In my case, with lots of good advice from this thread, I've built several planes with a Clark Y canard, incidence at +2deg, and symmetrical main wing at 0 deg. I then go to the C/G Calculator and dial in a Static Margin of 10%. Works every time, notwithstanding pilot error and incorrect lateral areas.

I wonder if the C/G calculator we've been using allows for these airfoils and incidences. Maybe the Static Margin at 10% is the point where we set up a loading on the canard which is sufficient to keep the plane in trim at normal speeds, but only because of the relative incidences.

so, going back to the Star Chaser..
Quote:
On one version the main wing is at zero incidence and the canard is at two degrees positive. The second version has a positive main wing incidence with a lesser angle on the canard. I feel that the CG positions would be different on the two...
It seems to me that the second version would not fly straight and level with the same C/G as the first one because the neutral point would be further back since the canard would not be producing as much lift. In that case, either the C/G needs to be further back or the Static Margin will be more.

Not only that, I wonder how they can contrive for the canard to stall first! A difference in airfoils? And another thing ... on the take-off run, the main wing will start to fly first. That could be fun for the spectators!

Nick
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Last edited by nickchud; Feb 21, 2011 at 10:42 AM.
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Old Feb 21, 2011, 11:37 AM
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Nick, I think Don's point is that, by the time you have dialled in the necessary elevator trim to achieve straight and level flight at a given speed, both models with the cg in the same place, would in fact be flying with very similar relative angles of the canard and main wing.

I suppose it is possible that the trim required might change the section of the canard enough to produce some difference in the downwash over the main wing but that would be a second order effect.
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Old Feb 21, 2011, 11:47 AM
What could possibly go wrong?
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Hi Trevor!

Yes, I agree. The necessary elevator trim is the key to it all, because that trumps the canard incidence. In the end, we're correcting for the fact that the second version of the Star chaser has got the wrong canard incidence. Once we get the canard incidence / elevator trim right, we'll be able to use the same (correct) C/G and we'll end up with the same loading on the wings as version one. Though, as you say, there might be different downwash effects and efficiency.

Nick
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