sentences:  While the reduction in sweep-back actually increases drag it also increases lift allowing a lower AoA and the extended wing span decreases the induced drag (wing tip vortex) resulting in a net reduction of drag.Unfortunately, his optimized design uses too simple of a model; he realized that had more variables, such as viscous effects, been taken into consideration, the resulting model would have been far different.The other major limitation of the single point approach is that it only optimizes the wing for one speed and lift condition.