Overview of the BOLT-1B Flight Experiment

The Boundary-Layer Transition (BOLT-1B) flight experiment was a successful reflight of the 2021 BOLT-1A mission, conducted to study hypersonic boundary-layer transition physics on a complex geometry with concave surfaces and swept leading edges. Following a vehicle flight instability in BOLT-1A, the Johns Hopkins University Applied Physics Laboratory, the German Aerospace Center Mobile Rocket Base (MORABA), and the Air Force Research Laboratory collaborated to redesign and refly the experiment. Launched in September 2024 from Andøya Space, Norway, on a single-stage Black Brant VC sounding rocket, BOLT-1B achieved Mach 7.2 and low angles of attack. The forebody experiment included hundreds of instrument channels measuring temperature and pressure on smooth and stepped surfaces. The experiment characterized boundary-layer transition during ascent and descent and validated improvements to vehicle stability modeling. The resulting dataset advances understanding of hypersonic transition phenomena and complements prior BOLT wind-tunnel, computational, and flight research. An overview of the flight experiment is provided, with additional technical details in companion papers by the wider team that are cited throughout.