antter,

Yes, you are right. Geometric pitch is relative to the chord angle and has little to do with the airfoil aerodynamics. It's just a geometric reference point. I got a little confused.....hehe
Zero lift angle, as any AoA in a polar is measured between the airflow and the airfoil chord line. So, when we say that a given airfoil has -6 degrees of zero lift AoA, it means that it's chord line makes an angle of -6 degrees with the airflow.

Here's an interesting website that gives an insight into some aspects of propellers.
http://www.apcprop.com/Engineering/e...ng_design.html

I will make a little research and see I can find the major prop brands airfoil section. With them, I can them draw some polars for them and play a little with the results and see if I can come up with a way to calculate thrust by treating the propeller blade as a rotating wing.

I will keep you posted....