pull-pull setup tips
 

Morning all. I'm about to start building a YAK with a pull-pull system. Are there any tricks or tips to setting one of these systems up? Never done one before, so this should be interesting (at least for me anyway).

TIA

RE: pull-pull setup tips
 

Just remember to keep your geometry the same. The width of the servo arm should be the same width as the control arm.
Also, keep the control arm on the rudder either flush with the hinge line or slightly behind (1/32-1/16") Keeping the control horn slightly behind the hinge line will cause whats called reverse akerman. In other words, at full deflection one of the cables will go slightly limp which is OK. If the control horn is in front of the hinge line then you will have problems with binding. Not good.

What kind of control horns will you be using?
EDIT: Not sure how that smiley got in there. Can't seem to edit it out.

RE: pull-pull setup tips
 

Not sure what kind of horns yet. I'm going to check what came in the kit. More that likely I will change them out to some Dubros.

RE: pull-pull setup tips
 

OK. To clarify one thing. When we say to keep the horn and servo arm the same width, it refers not to the control horn itself. It refers to the spot on the control horn where the clevis goes. Make sense?

RE: pull-pull setup tips
 

Also make sure to consider the thickness of the rudder when measuring how far the clevis is away from the hinge line. You can't just use the control horn's distance from the clevis connection point to the base of the horn. You might be off as much as a half inch or more. It's the distance from the hole that the clevis goes in, to the hinge line. So measure from the clevis connection point to the base of the control horn. Then add one half of the rudder's thickness. Make sure the servo side is the same distance from clevis connection point to servo shaft center. Try to not cross the cables if you can. Otherwise you get more slack on one cable when you go to full deflection (the one not being pulled). If they are NOT crossed, the cables stay at a close tension throughout the defelction (less slack). However sometimes they need to be crossed due to the fuse geometry. Either way, it will work.

RE: pull-pull setup tips
 

I agree with Joe but if you cross your pull-pull lines, it certainly lessens the exit slot that's needed when you use the parallel system.

RE: pull-pull setup tips
 

That's exactly what I happened to me on my CAP232 120. The slots would have been huge so I crossed the cables It does have slack on one side but it flies great. I do a lot of 3D and IMAC stuff and it works really well. Scott at SWB told me to not cross them but I did it anyway.