C 130:
When you put the servos in the wings, and the servo arms face the wingtips, they will work in opposite directions. Also, don't forget, with two servos in the wings, you have twice as much aileron power than with one. I always think of the servos in order of importance. Ail. el. thr. rud. That way I don't forget. Wish I could remember other things the same way.