The purpose of the round or star shaped output arms is in one case the aileron pushrods can attach to the wheel not directly even with the the rotation center. This will provide something called differential aileron throw without the need for a computer radio or dual aileron servos. The purpose is to minimise 'adverse yaw' which is just the tendency for the nose of the airplane to try to point away from the direction you are turning when using only ailerons (the down moving aileron is more draggy than the upward moving one making the nose want to point the wrong way).

It makes for a much prettier flight and is done with a highwing trainer just by using a round or star servo wheels and making the Aileron pushrod just slightly longer so they attach to the wheel just beyond the servo pivot points.


John