Hi all, I have implemented a nonlinear lifting line method to estimate lift/induced drag of a typical wing. This method utilizes 2D lift coefficient data, and uses a numerical technique to solve the nonlinear equations. The program I have written in MATLAB is working, though I would like to confirm one key aspect of the results. When I run the program for a swept back wings, I see that the induced angle of attack goes to negative towards the wing tip (aeff = a(geometry) - a(induced)). From what I understand, towards the tip a wing, the local angle of attack there is greater than the freestream angle of attack, due to the induced flow, therefore a(induced)should be negative. So my question is: Is getting a negative value for the induced angle of attack actually correct? I have a hard time trying to grasp this physically. sample data induced angle of attack at the wing tip 0.024249058497046 (Close to wing tip) -0.051359819152125 -0.088120053792167 -0.019725856790100 0.457096103863267 (wing tip) Any help would be much appreciated. Thank you.