Differential advantage or not

[RonPlanes]

Can anyone tell me the disavantage of setting up ailerons for differential

[Highflight]

For most aircraft, you WANT differential where either aileron will go more up than down.
It becomes downright important on high wing, slow flying airplanes like a Cub or Citabria.

The reason for it is that in a turn, the aileron that goes down creates drag that tends to pull the wing OUT of the turn you're trying to make. It is entirely possible to enter a turn and have the airplane turn the opposite direction in severe cases.

For example, say you are entering a right turn. The right aileron goes UP and not only pushes the right wing down because of it's deflection, it also assists the turn by adding drag on the low (right) wing.
The top (left) wing's aileron goes down and deflects the left wing upward, but it ALSO adds drag which is opposite to the direction of the turn. By limiting the down movement of each aileron, turns become much smoother and prettier.

It doesn't matter how you do it, but it's always easiest to set it up in a computer radio through the software. What you are describing is a mechanical way to do it, buy what you seem to be trying to do is to PREVENT any differential. In fact, you WANT differential; just be sure that you don't set it up opposite to what is intended.
In the upper part of your diagram, you would be doing differential properly if what you show is of the servo being mounted on the top of the wing. But if that setup is done with the servo mounted on the bottom of the wing, then you would have opposite differential which would be a problem.

I hope I didn't over explain here, but I don't know how much you understand of basic aerodynamics.

Highflight

[Twostroker]

Aileron differentialis is actually a good thing which helps the airplane fly better. When a bank turn is introduced with the ailerons one aileron goes up, one down depending on the direction of the turn. The aileron that is down during a bank turn creates more drag than the one that is up, which causes the airplane to yaw in the direction of the down aileron. To correct this the rudder is used to keep the tail behind the plane or in the slipstream of the direction of flight. So the correct way to use aileron differential is to make the ailerons travel less down than up to reduce aileron induced yaw to the airplane. Properly set aileron differential will help bank turns look better, fly better, and fly faster. It will also keep aileron rolls stay more axial.
Tim

Just like Highflight said.