Help! Ailerons with Under Camber Wing?

[luvmy40]

I seem to remember reading that under camber wings do not work well with ailerons. Is there anything to that or am I misremembering?

I'm building an FT Old Fogey that I cut last night and I was thinking about adding ailerons. Bad Idea?

Thanks!

 

[Mr NCT]

I scaled the DR1 to 150% and tried ailerons on the upper wing and then the upper & middle wings. It did not work well, incredible adverse yaw without much banking. Tried having the ailerons deflect up more than down, no success. The plane flew very well with just elevator & rudder. Don't know the aerodynamics behind it but it wasn't pretty.

 

[Tench745]

My Curtiss Jenny had ailerons and an undercambered wing. I don't recall them behaving that unusually. The real Jenny was a very slow, stable plane with loads of adverse yaw that you turned mostly with rudder, and this model was much the same. It was not a bank-n-yank plane at all. Hard to say if the under-cambered wing played a large part in this or not.

 

[danskis]

Differential may be the key or not. This is a WAG. You'll have a lot more pressure on the down aileron than on the up resulting in a ton of drag on the down aileron. So you make the down aileron go down a lot less than the up. You might even end up with the down aileron hardly moving. It may fly better with just the rudder. Put the rudder on the aileron stick?

 

[FlyingTyger]

I think it depends on how much camber. I have built several with ailerons that did have any issues. The Tiny Twister and Kaos even proved to be fully aerobatic and capable of inverted flight. But both of those and the Twin Skylark used a very shallow cambered wing.

 

[CapnBry]

For reference, I made the Ridge Runner (which used to be on the FliteTest main page but now the link is dead). It had undercambered wings and I added ailerons. It worked flippin' amazing. I've built 3 other motor glider designs since that and nothing has come close to performing as well.

It probably does depend a lot on the airfoil how effective they are, but ailerons definitely can work on undercambered wings. Experiment and see how it goes! You'll still have rudder to fall back on, right?

 

[RedTwilight]

Some of the adverse yaw could also be contributed to the dihedral of the wings.
So if you add ailerons, you might want to reduce the dihedral a couple degrees.

 

[luvmy40]

For now, I've decide to leave it as a 3 channel plane. If it survives more than a few flights, I may add the ailerons just to see how it does.