Ascent air data system results from the space shuttle flight test program

Abstract

The ascent air data system of the Space Shuttle consists of a simple biconic spike probe on the nose of the external tank. Pressure measurements were calibrated in a wind tunnel to obtain vehicle attitude and speed (relative to the air) and dynamic pressure. The wind tunnel test data analysis and the calibration are discussed in terms of test problems and calibration parameter formulation. The flight pressures are traced from telemetry data to final air data products. Analysis of the flight results showed that static pressure could not be accurately determined at the higher Mach numbers (above approx. 2.0). By replacing static pressure with data from a postflight estimated trajectory the ascent air data system performance met the user requirements. Lessons learned are enumerated, the most important being the need for a thorough systems integration effort.