BOLT II Flight Experiment Direct Wall Shear Analysis

This white paper presents the findings from the BOLT II flight experiment, which aimed to measure boundary layer transition and turbulent heating in hypersonic flight conditions. The BOLT II vehicle, a derivative of the original BOLT design from the University of Minnesota, features a cylindrical nose and various concave surfaces. The paper outlines the instrumentation used, including fourteen wall shear sensors strategically placed to capture data during both ground and flight tests. The ground-test campaign was conducted at the CUBRC LENS II facility, where three tests varying Reynolds numbers were performed at a nominal Mach 5.3. The flight-test campaign involved launching the BOLT II vehicle from NASA Wallops, where it reached a peak altitude of 185 km. The results documented in this paper compare wall shear data from both experimental campaigns, providing benchmarks for future hypersonic flight studies. The findings indicate significant differences in boundary layer behavior between ground tests and actual flight conditions.