Interesting question.
But consider that if you have the thrustline and the rudders zero lift angle of attack line as the same and then force that line to rotate with the CG tangent to the circle then you will by default have outthrust and you will have positive rudder deflection.
The greater the distance from the CG these are then the greater effect they will have.
To cancel out these natural outthrusts you would have to design the model in a curve that matches it's flight path, and indeed some speed models do exactly that.
So do you need the natural outthrusts of classically designed model?
Absolutely, but the real question is do I need more?
To me that's a depends question.
Chris.
P.S.
See attached image where A is the engine, B is the rudder, C is centre and D is the CG tangent to circle.
The line between A and B is your 0-0 setup, the thrust is outboard of the flight path as thus will provide outthrust and the rudder will weather cock towards the flight path pivoting around the CG thus providing yaw.
I think you guys are concerning yourself with stuff that is *far, far* below the threshold of normal building tolerances and variations. It's interesting in a hypothetical sense but not important to the problem at hand - and in any case, it's built like it is built, you aren't going to split the fuse lengthwise and bend it to follow a 65 foot radius.
How much engine offset you want is an interesting question that at least to first approximation depends on the wing asymmetry and where the lateral CG might wind up. But offset is an *extremely weak* trim adjustment meaning you have a very large tolerance , or, putting it another way, it makes very little difference, so guessing wrong won't make much difference (as long as it is not *inboard* - make sure is is not aimed in at you).
The rudder, on the other hand, is *extremely powerful" , so the chances of determining the correct setting
a priori is probably inconceivable. I can easily detect the difference in 1/2 turn of 2-56 clevis - 0.009", that is 9 thousands of an inch - on a 1" high horn. or about 1/2 a degree.And my rudder is likely much less effective that this one. Mine is about 1 1/4" in chord and 8" high, and I hae a very large fixed fin and a very large aft fuselage.. This airplane is around 3" of chord , only slightly shorter, and has a fuselage that provides much less restoring force.
I suggest putting it dead straight ahead or the tiniest breath to the right (like, .005", not 1/4") and then adjust based on what you see. And, consider that it might have to *change from day to day*.
Brett