### Drag Coefficient & Lifting Line Theory - Aerospaceweb

In fact, the above equation becomes identical to that predicted by Thin Airfoil Theory if we let the aspect ratio go to infinity, as it would for an infinite wing, and if we assume the lift curve slope of the airfoil section, C l α, is the theoretical maximum value of 2π. If you know the actual lift curve slope for the airfoil on a particular ...