If you are setting up a flat wing trainer, then many recommend using the two forward arms on a six arm servo arm. You still want them equidistant to the center with the servo centered and the trims center. They will be approximately 60 degrees forward.

What this does, is sets up aileron differential, since the aileron has more authority in the down angle, than the up angle. This differential allows more throw on the upward motion on the opposing ailerons downward motion, since the flat bottom allows the downward moving aileron to be in cleaner airflow, hense more responsive.

You usually cut off the four other arms, one at 90, one at 270 degrees and the others at 0 and 180 degrees.

Hope this isn't too confusing, but all the flat bottom trainer's (including my own) have flown very well with this set up. Even many large aerobatic airplanes profit from aileron differential.

If you are using a computer radio, you can set this up and adjust it. If you are using a standard 4 channel, then the best you can do is what I recommended.

Hope this helps,

Mike Boyd
AMA 7197