nice bit of maths but not much common sense, I was referring to the leverage not servo torque and mechanical advantage, that has been explained very well by Doug.

with a 3D plane you require a 1-1 ratio with the servo to gain the right amount of throw, that’s a fact and something we have to live with. now you go away and in practical terms (not mathematical terms as in maths you are not mounting your horn onto balsa wood!) mount your horn at 1/4" from the hinge line and with a 1/4" servo arm on your funtana and I guarantee your wings would have fallen off within 1 circuit.

now do it with a 1.5" horn and 1.5" servo arm and it will be fine, resolution will be better and so will the slop as although as you said the torque relevant to the length of the arm has reduced, so has the forces that are required to move the surface by the same amount.


how many TOC planes do you see with short arms? and why to fiber classics / comp ARC make sure they supply both servo arms and horns (which are LONG) with their kits.

Dave