I understand that the downward motion of the aileron causes the wing to produce more lift, and the upward motion spoils lift, thereby making the airplane turn, either way. (theory)

Why do they work on flat airfoils like spads the same way?

Can anyone chime in?

Thanks
Joey

Flat airfoils have lift also.

Any airfoil has what is called a camber line. A flat plate and a 15% symetrical section both have a 0% camber. Ailerons act to modify the camber and thus change the lift and angle of attack for that portion of the wing. Even for a flat plate this holds true. Moving the aileron down increases both the camber and the angle of attack. Moving it up does the opposite.

That help?

Yeah it does, THanks for the input. I was under the assumption that flat airfoils are not nesesarily "wings".

A kind of picky point but ailerons do not turn a plane, they roll it. In order to turn you have to use the elevator in conjuction with the ailerons to turn or have dihedral to inject some yaw forces.

Airplanes turn because they are banked. Pure and simple

Once a bank is established, and all controls neutralized, the airplane will make a nice, 1-gee turn. Now...If you want to maintain altitude, roll in or out of the bank, compensate for engine effects, airframe rigging, and so on, you'll add one or more control deflections into the mix.

An airplane turns when it's banked because the lift vector pulls the airplane laterally, and it weathercocks into the resultant relative wind. Because it all happens together in a dynamic situation, you don't actually see this, but only the result of a smooth turn. You don't need to have any other controls added to make the airplane turn once the bank's established (assuming proper setup, rigging, etc).

Wolfgang Langeweische gives an excellent description of this in his seminal work, "Stick and Rudder".

Nobody ever fly one of the bipes like the TENSOR?
Banking it does nothing -
turns are done using the rudder .
As more people do aerobatic craft -- what is and is not possible, continues to change .
Flat plates are extremely effective airfoils -for the task they are used for
The TENSOR's responses to rudder and ailerons would likely baffle someone who has never looked into this type of force arrangement

Engineers try to make controlled flight very complicated, efficient, precise. Foamies and spads try to make it very simple, cheap, don't care about efficiency. All control surfaces work by deflecting air, pushing against whatever it is connected to. Stick your hand out the window of a car and rotate it .... a crude aileron. You can get a degree in aeronautical engineering if you need a more complete answer. Ailerons usually work to some extent or another despite what they are attached to.

Here's my take on why an airplane turns (this is better than working...). I must admit that this theory comes from flying full sized aircraft, and as some of you have mentioned, there is a whole new breed of 3-D R/C aircraft that have some amazing power-to-weight ratios that may throw a few physics curves into the mix...

An aircraft turns because the horizontal component of lift is being vectored one way or another, as Bax states. I have to disagree with the point that "Once a bank is established, and all controls neutralized, the airplane will make a nice, 1-gee turn". It will continue turning, however, it won't be at 1g. When an aircraft is in a turn and holding a constant altitude, the wing loading goes up. A 60 degree bank produces about 2g's. 45 degrees, about 1.41g's. Ailerons roll the aircraft into a bank. Some of the wing's lift is now being vectored in that direction and the aircraft turns. Now that all of the lift of the wing is not in the vertical orientation, angle of attack must be increased to hold altitude. This is what the elevator is used for. In a turn, rudder controls adverse yaw, nothing more. The aileron that goes down increases lift and increases drag, yawing the nose in the wrong direction. I think this is tough to see in a model, but in a full size airplane, it is very evident (especially a sailplane). This post is almost as long as "War and Peace"...sorry...

Most of the comments here , rely on the very common layout of full scale craft .
That is, the wings provide most of the lift.
Now look at a craft which has huge vertical plates -located at the CG (or lots of side area).
On the TENSOR-as an example --banking it -or to state it more correctly , rolling from the horizontal wing position, the lift does not change much-- sorta like a box configuration-where any two sides will provide same amount of lift.
The crazy thing that happens --is that the box -tilted to 45 degrees -becomes quite stable ---
Anyway - the response of these craft is quite interesting .
If you have not tried em -and you think you have a thorough grasp of "what makes it fly", you may be in for a surprise.