I'm building a 40 size canard. My ques. is, what happens if I have too much vertical stab.{ about30% too much?} I know, why not make it smaller? Well let's just say there design reasons for making it this way. Roger

Too much vertical stab will cause spiral instability. If you trim for straight and level and let go, the first time the plane hits turbulence the nose will drop and the plane will enter a spiral dive. Unless you plan to fly hands off a lot, it will most likely not pose too much of a problem for you.

Hi Roger,
If you would like excellent Canard design parameters check the
5/95 Model Aviation.
Can not imagine why you would want 30% vertical stab area, N.G. !!
10% of the wing area is reasonable if the vertical is in the area of the
wing. If forward at the canard, perhaps 7% max.
Good luck and have fun!

Hal [email protected]

Hi Hal....are you talking about putting the vertical area up front, forward of the CG? Wouldn't that make it swap ends, like an arrow with the feathers up front? Maybe I misunderstood you.

Hal, I know it's not the best design,but because of other [funkie] things I want this thing to do, I am stuck with to much vertical. My question is what to expect? Roger

Roger;
A good test is to make a small hand launched glider, 12/14in. and see what it does. A good way to find CG. Stab, wing incidence and such things. When it works on the small one it will work on the big one.

Flypaper, I'm tired of building on this project. I thought all you smart guys have been there and done that and could help an old man out. I do appreciate the knowledge shared on the forums.



Roger

Got that CG problem figured out yet? Milton could probably give you one of those Cox .049's to fly it.... Would definately help you with your nose heavy problem....

30% isn't all that much larger.... I've gone at least that amount smaller on some planes.. which showed me the original vertical was larger than it needed to be.
With ailerons, it should be controllable.
The biggest problem with canards is the fragile front end. Usually there's a big hunk of motor/firewall to take the "arrivals"...

Do you mean 30% of the wing area or 30% bigger than the 30% of the wing that it should be?

Canards DO require a larger vertical than conventional models do because if the very short moment arm between the aricraft neutral point and the vertical compared to conventional layouts. Chances are what you think is too much is either just right or may not even be enough.

I also second the little all balsa glider for testing. If you can't make a simple profile all sheet tester like this in under 1/2 an hour you don't deserve to own an Xacto knife....

What am I thinking, I have 6 Xacto knives so it shoud only take me 5 minutes to builb a handlanch glider.

Tall Paul; Thanks for the good information. This thing is a tracktor so the engine and firewall will get there first. My verticals are 15.5% of the wing area and as far aft as possible. It's in the covering stage so it's a little late for major changes. The C.G. came out about .5" forword but I can change it real easy. I'll let you know if this thing works. Dickeybird is in on a lot of the design thinking , so it may do something.

Roger