Hi Jim O.

If the plane needs negative elevator around neutral, then positive elevator at more rudder throw, I'll change the incidence so that the rudder/mix trend is always "one direction." The fidelity of the points is tough to get right.

On older setups swinging 40 degrees of rudder all the time, 2% mix to elevator used to make a difference. Now, we can perform knife edge loops on 18 degrees rudder throw, but elevator travel is still around 10 deg let's say ( unchanged).

why do I mention this? Because as long as the mix is one-direction, the "expo" is just a means to move the total travel closer or further from a standard linear mix. On my pattern planes with super effective lifting fuselages and yaw authority, and low rudder throw, the shape of the curve doesn't really matter. I just want enough mix in the range of rudder being used.

on my IMAC planes, I use around 10% mix and negative expo! Low lift fuselage and not very effective rudder, shape of the curve matters need lots of mix as rudder throw increases.
thx,
Jim W.