According to my Compufoil2000 program, the zero lift angle of attack for the AS series airfoils is -2.13 degrees. Quite a difference from what everyone is saying. With a 2.5 degree AOA at the root there would have to be over 4-1/2 degrees washout (4.63 to be exact) to get the tip at a zero lift angle. Not accounting for any torsional twist in the wing of course.
I believe Langford is correct with the 2.5 degree AOA at the root and then using 3 degrees of washout. The tip will still be creating lift. Fred Johnson Reno, NV