control surface settings
 

I am currently setting a trainer and the manufacturers book shows a different throw up vs down (5/16" up and 1/4" down). Now the answer might be simple but I'm stumped. If the control surface is level and the servo centered how can achieve a different throw, doesn't the servo move the same distance from center.

RE: control surface settings
 

Dave:
Its called differential ailerons.On a flat bottom wing, the down going aileron has more drag than the upgoing aileron, called adverse yaw. The drag on the down going aileron, say, to do a right turn the left aileron goes down but the drag on it is trying to make the plane turn left. One way to fix it is to put a servo wheel on the servo. drill two pushrod holes forward of where they would normally be, maybe 1/4 in. forward of the cross centreline. Now you can see where the holes move a shorter distance when the wheel moves forward and a longer distance when moved toward the back. Two servos and a computer radio is an easier way, but this way works fine with one servo. Hope it's not to confusing.

RE: control surface settings
 

Dave,

If you want to achieve differential, a simple way is set the control arms off 90 degrees relative to the servo. That said, typically the servo control arms are installed when the servo is in the neutral position 90 degrees or midpoint in their travel. If you install the arm a little toward the leading edge, or possibly trailing edge in some cases I suppose, the servo arm will travel less in one direction vis-a-vis the other. Try it out and you will get the idea. Differential should make a high wing trainer a better flier.

Good Luck!

DaveB

RE: control surface settings
 

You sort of answered your own question... The servo arm is not centered when the servo is at center.

Something else... Don't worry about getting it exact. The recommended control throws are just that - recommendations.

Most fliers will change them to their liking after a few flights anyway

RE: control surface settings
 

Thanks guys

It's all much clearer now.