Feasibility of measuring prelaunch wind profiles in support of sts operations with an instrumented aircraft

A feasibility study of using an instrumented aircraft to measure prelaunch wind profiles for the Space Transportation System (STS) operations is reported. A NASA F-104 aircraft was instrumented with airspeed sensors, and an INS system to measure the inertial vector. The aircraft was also tracked with a FPS-16 radar to provide a second ground speed measurement. The algorithms for extracting wind speeds from the measured data were developed. Four experimental flights were carried out at NASA Dryden Flight Research Facility to an altitude of 40,000 ft. In turn Jimsphere measurements, which are routinely used for STS launch wind profiles, were carried out at enveloping times and positions. Comparison of the aircraft measured wind speeds with those of the Jimsphere were made. Ninety-two percent of the data fell within the established statistical goodness of fit criteria. It is concluded that an instrumented aircraft can measure statistically equivalent winds to those of the Jimsphere up to altitudes of 40,000 ft. Experiments are continuing to measure winds at higher altitudes where flight speeds are supersonic.