NASA Dryden's F-15B testbed aircraft flew several flights recently in support of an experiment to determine the precise location of sonic shockwave development as air passes over an airfoil. The shock location sensor developed by TAO Systems, Hampton, Virginia, utilizes a multi-element hot-film sensor array along with a constant-voltage anemometer and special diagnostic software to pinpoint the exact location of the shock wave and its characteristics as it passes over an aircraft surface. For this experiment, the 45-element sensor was mounted on a Dryden-designed airfoil which was attached to the right side of the underbelly Flight Test Fixture on the F-15B. Tests were flown at transonic speeds of Mach 0.7 to 0.9, and the device isolated the location of the shock wave to within a half-inch. Project officials said that closer spacing of the sensors and underlying pressure orifices would result in even more precise location of shockwave development.