Ollie, I've never heard the description you used for Newton's law before. I always understood the airfoil more like a bent tube. Air goes straight in, and comes out at an angle. The net mass flow vector is your lift. I have also read studies of thin simple plate airfoils with knife edges. In these cases, there is little to no acceleration due to differences in curvature or path. But, they still produce lift as a function of attack angle. Any insight here?