RE: Composite-ARF Rookie II
Pitss SPS
I put them between the canard and the fus, this allows room them to rotate down 85deg to act as airbrakes, they are only needed between the carbon rod and metal joining attachement if you have cut the carbon bearing tube inaccuratly and have play in the linkage from side to side which may bind.
avicom
The elevons are not one surface they are two surfaces on either side, so the servo's are not fighting each other mechanically, you just have to ensure that the movements are equal.
Mike