Sonic-boom research activities in the Japan Aerospace Exploration Agency (JAXA)

Some sonic-boom research activities conducted in the Japan Aerospace Exploration Agency (JAXA) are summarized. JAXA started a scaled supersonic experimental airplane program named NEXST-1 in 1996 in order to establish advanced CFD-based design technologies. The flight test of the NEXST-1 was conducted in October, 2005 at Woomera test range in Australia. The sonic-boom signatures of the NEXST-1 were measured on the ground in order to confirm the possibility of demostrating the low sonic-boom design technology with scaled experimental airplanes for a future low-boom demonstrator program. The measured sonic-boom signatures were compared to the signatures extrapolated from the near-field pressure signatures predicted by CFD and panel method or measured in the supersonic wind tunnel. Low-sonic-boom design technology using gradient-based optimization tool with CFD is developed and applied to a non-axisymmetrical fuselage design concept in order to reduce the drag penalty. JAXA works on a human acceptability study in cooperation with Kawasaki Heavy Industries (KHI) using their sonic-boom simulator. Some low-boom signatures in addition to some typical N-shaped signatures with various peak pressure levels were simulated in the boom box and used for subjective test in order to collect the human acceptability data for future sonic-boom acceptability criteria.