I'm pretty sure xfoil was not intended to analyze such high angles of attack. For anyone who is interested, attached is a beautiful plot of what happens when an airfoil is rotated all the way to 180 degrees (from NACA technical note 3361).

Originally Posted by Holski77

Bottom right is CL vs CD, bottom left is CL vs alfa

Ah, well that's the problem. As DPATE said, XFoil is really only reliable up to stall. Frankly, I'm kind of surprised it converged in the first place at those high angles.

Hi friend.
this code for wind turbine profiles only if variable design variables and restrictions?
What would be the most important thing that I should modify in this code?
help me, please.

Originally Posted by leovj

Hi friend.
this code for wind turbine profiles only if variable design variables and restrictions?
What would be the most important thing that I should modify in this code?
help me, please.

I don't understand your question, but have a look at this more relevant thread:

https://www.rcgroups.com/forums/show...ion-with-XFoil

I am going to close this one now.