Aileron Differential

[Rwilkinson]

I fly sailplanes mainly, and I like differential in the ailerons. Do I need to install the wing servo with some mechanical differential. This is a quickie 500 arf from Lanier.

Rick Wilkinson

[DaveSawers]

differential in the ailerons will give a non axial roll in a pylon model and hence more drag. It's neither necessary nor desirable.

Sailplane is a different case entirely as the models tend to be self righting when ailerons are centred. This makes aileron differential potentially useful.

[Rwilkinson]

Thanks Dave

Rick

[john dee]

Actually whether aileron differential is needed is really only dependant on the speed at which a model is flying, also probably on aspect ratio. Gliders which fly slowly and have high aspect ratio will show more adverse yaw (the tendancy for the model to yaw in the opposite direction to the roll direction) which can be corrected to some extent with differential and/or with rudder coupling.

I have seen some electric pylon models which have only one aileron. Thats got to be 100% aileron differential. I wonder what that is like to fly?

[max-nix]

John
One aileron on the right wing is similar to using top rudder as it keeps the nose up during the pylon turn due to the drag. It is very nice to fly.

[DaveSawers]

I have seen some electric pylon models which have only one aileron. Thats got to be 100% aileron differential. I wonder what that is like to fly?

The main reasons for doing that are:

To reduce drag in the straight because there's only one aileron gap.
Make construction simpler.

Usually no advantage is gained since the adverse yaw makes for slower turns.

One aileron on the right wing is similar to using top rudder as it keeps the nose up during the pylon turn due to the drag. It is very nice to fly.

If you are having trouble keeping the nose up in a turn, first consider moving the CG back. If it's already where you want it, put some weight on the lower wing tip.

Using drag to correct a balance problem is not a good idea.

[Konrad]

Dave
Did I miss something? I usually find that a heavy lower wing causes over rolling. As the G loading goes up as the plane accelerate through the turn the mass wants to stay going in its original direction (down the straights not around the pylon).

FYI: I don't like single ailerons as the roll axis is off the wing. This gives a drag inducing up and down motion to the fuselage. I think it causes some midairs as control is not as accurate as one might want.

Konrad

[DaveSawers]

Dave
Did I miss something? I usually find that a heavy lower wing causes over rolling.

Oops. Yes. I agree. It's the other way.