On NACA airfoils we typically use in stunt, as AOA increases, the lift increases in a linear fashion up to 10 degrees. After 10 degrees(for 18% airfoil, 11 for 22%), the increase in lift for every degree drops off SIGNIFICANTLY while the drag keeps increasing exponentially. In other words, to try and eek more lift by letting the wing go to higher AOA is a loosing battle. I would look into other mechanisms of increasing lift.
Here's an idea worth checking out: increase wing area but use thinner airfoil to offset increase in drag. Difference in lift between 0016 and 0022 airfoils is negligible. 0016 becomes useless beyond 10 degrees, while 0022 is useless beyond 11. 0016 develops more lift between 5-10 degrees but like I said, the differences are negligible.
Well, not sure I agree with above. For starters, the airfoil data is two dimensional, airplanes are 3 dimensional. THe aspect ratio controls the real angle of attack because of the induced drag.
A low aspect ratio wing with the same airfoil and area of one with a higher aspect ratio will stall at a higher angle of attack.
Also, once the critical angle of attack on an airplane is reached the curve flattens and there is no futher loss of lift ( unless you go into supemanuverability ) due to the reduction in induced drag, so the lift and drag coefficients remain fairly constant around the "knee" which doesn't happen in 2-D flow .
Additionally, if you look at the curves for symmetrical airfoils you'll notice that the flat wing of a Guillows glider has the same curve as a Nobler. 2Pi with the zero-lift AoA at zero degrees.
Yeah, I'll give you we use flaps, but the changes in lift coefficient due to the flap deflection are not calculated as a fucntion of thickness.
SoI guess what I'm saying is airplane wings don't act the same as sections in a wind tunnel.
And you have to remember, that models fly at such low Reynolds numbers that there isn't sufficient energy in the flow to really apply Buckingham Pi to the results and assue dynamic similarity to the wind tunnel results.
Because of this, and the fact that test sections were typically small, it was common practice to pressurize the wind tunnel to increase the air density and push up the Reynolds numbers to numbers relevant to full-scale aircraft design.
Readers digest version: on a stunt ship aspect ratio has more to due with stall than the airfoil. Since all the airfoils we fly qualify as thick the stall will be trailing edge forward so the stall characteristics won't change much. In fact, once wings get thick enough they begin to stall before thinner ones due to the exaggerated turning of the flow required.
As I always say, we fly airplanes, not airfoils, and airplanes are much more complex than airfoils.