A ten-year engineering research project on a super/hypersonic transport propulsion system (HYPR) initiated by AIST (Agency of Industrial Science and Technology) in 1989 has been successfully completed. The HYPR project was aimed at establishing the technology base for a propulsion system of supersonic/hypersonic transport (SST/HST) aircraft that will fly as fast as Mach 5. The project proved the feasibility of a combined cycle engine (CCE) for SST/HST by developing and running the world's first CCE , a combination of a variable cycle turbofan engine (VCE) and a methane-fuelled ramjet. The development of the CCE began with a variety of component tests, followed by the development of the high temperature core engine (HTCE) and VCE. This step-by-step approach led to steady and solid success.

Based on this success, a new project was started in 1999, titled "Research and development of environmentally compatible propulsion system for next generation supersonic transport (ESPR)."

This paper introduces the various achievements during the ten years of the HYPR project, and the prospects of the upcoming ESPR project.