Hey guys, i'm trying to do a bit of research here. can you tell me some planes that need alot of coupling in knife edge? some that don't need too much, and some that need hardly any?
thanks, just trying to figure something out.

My 64" Yak is about as honest in knife edge as you can ask for, almost perfect in pitch and roll. On the other extreme was my U Can Do 3D, totally useless in knife edge, a real pig in comparison

My 2 cents worth,
Rob

My Seduction Freestyle from EZ have no coupling AT ALL!!

I read that you can mix it out. What mix do you need for that? How do you set it up, I mean how do you know if it has to be + or -?
thx

Not really my preference to mix it out. Can make just flying the plane really complicated. But it'll just be a rudder to elevator and aileron mix I suppose. Just memorize what you had to do to get it to go straight and then adjust. I THINK!

Yeah Spacey is right on,
An example, if it pull to the canopy when you try for level KE then first check your CG and aileron ailignment, if all is good there then mix "Rudder master" "elevator slave", look at the elevator while you hold in what amount of elevator you remember holding in and then adjust the % of the mixed elevator untill the right amount of rudder makes the right amount of elevator. the good news is that once you get it, its ussualy linear enought that it shouldnt screw up the rest of how the plane flies in other words it just makes the rudder do yaw only, like it should the mixing should be invisible to you when its set right, lots of takin off and landing those days... same for the ailerons remember, you gota do it for right and left KE.
nose heavy will pull canopy, tail heavy will push to the belly, ailerons is compensating for design or weight distrobution
Uproar, you designing something? keep us posted[:-]
I scratch build my own designs almost exclusivly, and havent had to mix out KE for a few designs now, its really hard to calculate out because even the landing gear and where you put the batt can scew it up. but (from my experience) [:-]its all about finding the aerodynamic center of the fuse in the vertical plane, and balancing it there, Bla bla bla.. i could go on and on just say SPADSTICK SHUT UP!! sorry for the spelling..and grammer

Excellent info guys thanks

UPROAR, You asked what planes "need" coupling, i would say no planes "need" coupling, coupling, both pitch and roll are a bad thing You have to do a lot of corrections if a plane couples. My 65" OMP yak has the least coupling of any plane ive ever flown.


We dont need no stinkin' couplin'!

Not meaning too hijack this thread.....but for the benefit of those interested....SPADSTICK! How can you find aerodynamic center? Any links to this subject? Help appreciated.

Thanks

Pitts bipes need some opposite aileron to hold straight knife edge and maybe a tiny bit of elevator; right and left roll coupling are slightly different due to P factor/right thrust. My old Banshee pattern plane had the wing and stab and rudder area very close to the thrust line and did perfect knife edge with no coupling at all. JIM

GAGAK,
I think i should have said center of area.