My own personal observation of how different thickness airfoils behave is this: Thick sections will stall at a LOWER Angle Of Attack then a thin section, but the thin section will stall more abruptly. I suspect this is due to the fact that air does not like flowing around curves, especially in a flow field where the pressure is increasing, ie. top of the wing behind the thick point. (Adverse Pressure Gradient) The thick section typically has MORE curvature in this case then the thin section. When the thin section does finally depart, it does however with less indication and more suddenness... (This is admittedly a subjective opinion/observation)

http://www.rcuniverse.com/forum/upfi...27/Ca81759.jpg

maybe this one Dick?? LOL