using AVL; vortex lattice method from Drela.

[nico]

Hello,

I am using AVL (see http://web.mit.edu/drela/Public/web/avl/) a vortex lattice method (and more) written by Drela and Youngren.
Wonderful program, but I am struggling a bit on a particular point; from the spanwise load, I would like to go switch to Xfoil to look at section design. Problem is how to get the effective angle of attack of the foil? (angle_eff = angle_inf - angle_induced)

AVL outputs the downwash angle along the span, which I think is the induced angle, sounds great but;

for me induced angle (along the span) can also be found from
1) atan(CDi/CL)
2) alfa_ind=alfa_inf - CDi/2pi

so then if I compare those 3 ways, I get different answers...