Stall angle for zero-pitching aerofoil
 

I've been looking at some aerofoils for a college lifting body project, and have been drawn to the idea of using a non-pitching aerofoil.

Most common aerofoils e.g. Clark Y, tend to have the stall angle pretty close to the maximum coefficient of lift (Max CL) angle.

Airfoil Investigation Database - Showing CLARK Y

Major exceptions to this are zero-pitching, non-pitching or, I guess you could say 'reflexed', aerofoils. In some cases, such as the Clark YS, the stall angle is almost half the Max CL angle.

Airfoil Investigation Database - Showing CLARK YS

In this context, what is meant by the stall angle, as its evidently not what I would think of as a stall in the conventional sense?