http://www.modelaircraft.org/mag/hur...rmgeometry.pdf

Hey, good find Tim. If you scroll down the page, it does show nicely what we were trying to say.

On the US 60 I am setting up now, I did use DuBro ball links on the aileron and elevator servo arms. This is the first setup I have ever had where you can't feel any slop at all at the aileron or elevator. The ball links do a great job of eliminating the twisting force that you can get on the servo arm just using clevis's. They are a little larger hardware than what we are used to seeing on a 40 size plane but that is okay with me because of their functionality. Of course you still have to have a tight fit where the clevis goes into the control horn or you still will have some slop. (my setup just uses the ball link on the servo arm)

On this US 60, I made my own carbon fiber pushrods and expoxied a short piece of 4-40 all thread in each end. Just a dynimite setup and looks very cool where the carbon fiber pushrod hooks to the ball link. I am using the thick red servo arm that comes with Hitec servos and it seems to handle the ball links okay.

Ernie