HIFiRE-5 Flight Test Results

The Hypersonic International Flight Research Experimentation (HIFiRE-5) is a hypersonic flight test vehicle designed to investigate the aerothermodynamics of a three-dimensional geometry. It is a 7-deg minor-axis half-angle elliptic cone with a 2:1 aspect ratio and 2.5mm nose radius. The flight test occurred in April2012, but the upper stage of the sounding rocket failed to ignite, resulting in a peak Mach number of about 3 instead of the target of 7. The instrumentation (almost 300 thermocouples and 50 pressure transducers) performed well and provided a wealth of supersonic aeroheating and boundary-layer transition data. The pressure transducers indicated the expected dependence upon angle of attack and yaw and offer a check for the inertial measurement unit. Heat flux was calculated from paired thermocouples and boundary-layer transition locations were identified from the heating rates. Two boundary-layer transition mechanisms were encountered during the supersonic descent. One mode leads to transition over the acreage of the vehicle and correlates well with Re-x; the other mechanism causes the leading-edge boundary-layer transition to advance rapidly over a small range of freestream Re and is suspected to be roughness-induced. The good performance of the instrumentation increases confidence in the success of a repeat flight.