Angle of Attack Derived from Pressure Measurements on the BOLT-1B Flight Experiment

The Boundary Layer Transition 1B (BOLT-1B) flight experiment successfully obtained detailed measurements of hypersonic boundary-layer transition and turbulent heating on a sounding rocket vehicle at Mach 7.2. The experimental forebody was instrumented with pressure transducers intended to aid in the estimation of the angle of attack; however, the pressure measurements suffered from drift during the flight. Using reasonable assumptions about the vehicle motion based on complementary sensor data, a method was devised to filter the pressure data, remove the drift, and correlate oscillatory components with computational predictions to estimate angle of attack. The resulting pressure-derived angle of attack and sideslip angles compared favorably to conventional vehicle attitude solutions, but with improved agreement to measured heating data on the experimental forebody. This paper will describe the methodology, estimated angles, assumptions, and uncertainties inherent to the method.