Hi,
What do I need to adjust to get a straight line knife edge without adding elevator?
I would like to get it a little more nuetral, it's pulling towards the belly.
I'm flying a OMP Yak 65''.

I have my C/G dead neutral.

Is it in the angle of the motor mounted, or aileron trim, as far as reflex or camber.

Appreciate any tips,

dave hauch

What does it do in a vertical downline? If it pitches to the belly there too, you can move the cg forward, this will result in a click or 2 of up elevator trim to fly straight and level. This will give you the needed correction automatically for the knife edge and downlines. Of course everything is interconnected, so a more fwd cg will affect other maneuvers too.

Dave,
Almost all airplanes, especially scale types, have some pitch coupling inherent in their designs. Without going deeply into the subject of CGs and stab/wing relationships, the best method to fix knife-edge coupling is mixing it out with your radio. Check your vertical uplines and downlines. If these are straight then leave your CG and thrust alone. CG changes can fix pulling or tucking in downlines, thrust can assist with uplines. Again, use your radio to mix in the elevator with rudder as it is perfectly normal. Changing other things will adversely effect flight attitudes that are far more complicated to mix back to neutral.

As it is a monoplane, your mix should be quite linear at most speeds and rudder deflections.

Mark

Mark; when you mix, are you putting it on a switch?

d hauch

I'm not Mark (obviously...) but I have never felt the need to have the mixing on a switch. Why would you want to switch in adverse rudder coupling?

Maybe as you are setting up the mix you might want to do this, to get a feel for the effect of the mix, but once it is right you won't ever want to go back!

James

If it's not on a switch, then you have say down elevator mixed in every time I use the rudder?

I wouldn't want that when say I'm trying a flat turn, or if I'm hovering, ect...
What then?

dave hauch

Hi Dave,
James is right. Whatever tendency the rudder causes in knife-edge will be there in wings-level flight also. The mix will actually assist in decreasing the workload in a flat turn rather than increasing it. As far as hovering, the elevator moves so little in a mixed condition that it should be completely unoticable.

Getting deeper into the subect of mixology, if you are using a radio that allows multi-point mixing and have lots of patience, then you can customize that mix for different percentages at different rudder deflections (and even throttle settings) and create a complex mix that allows perfect knife-edge loops without doing anything other than pushing throttle and rudder. Me, I have never mixed one up like that but I have seen it done.

Mark

Good point Mark.
Not going to need just a tad of elevator for the coupling.
I forgot about I could multi-point mix, do it all the time with my sailplanes, I love messing with this stuff in the radio.

Thanks!
dave hauch