Assuming the 3/8" offset from the rudder is toward the rudder, not the spinner, you get 0.025" slack in your cables --> really not bad for crossed cables as previous tests showed something like 1/8" to 3/16" slack in crossed, straight servo and control arms in longer-than-36" setups (which diminishes the effects of wrong geometry).
Rules of thumb :
- If you cross cables, use the same lenght on the control and servo horn, all straight. The drawback is that you can't get mechanical advantage without going through was Sylliness did. If you cross cables with straight servo and control horns, you get the worst possible slack (not saying that the slack obtained in innacceptable).
- If cables are not crossed, more room for error and mechanical advantage is possible without fussing too much. but some slack in cables will happen by the maximum throw.
- The farther away you are from the servo the better. It has to do with the angles of the cables relative to each other I think.
I think I would trust what SWB says as the geometry of pull pull systems is not that complicated using a computer...
I think if you cross the cables, that .009" becomes .009" of tightening... you would need to offset the control horn behind the hinge-line by .009".
Do you build with that kind of precision [X(] ??