[hypermiler01]

The reason that the noses and wing edges of airplanes are not razor sharp is not because it wouldn't be more efficient, but because they are frequently subjected to gusts and angles where the leading edges are not in line with the oncoming air, and the air would shear at the edge and stall, rather than following the curvature around to the top wing surface.

But the radius of the leading edge is kept as small as possible to avoid pushing air while being large enough to do the job of maintaining attached flow at the necessary range of pitch and yaw.