phase, Whitcomb realized that the wing's pressure distribution must be modified to delay and weaken the shock wave created on the upper surface where the high-velocity flow decelerated to subsonic. Using intuition rather than mathematics, he built a 2 ft chord wing section and tested it repeatedly in the Langley high-speed wind tunnel, adding (with auto body putty) or removing (with a file and sandpaper) material until the desired flows were achieved.

Although a low-drag airfoil (in the transonic range)