1. PREPHA program (1992-1999) was devoted to research in supersonic combustion and hydrogen fueled scramjet technology. AEROSPATIALEMATRA, ONERA and DASSAULT-AVIATION had designed several vehicles, several engines, several air intakes, and select a final assumptions for each. In PREPHA, several propulsion concepts refered as Bl, B2, DCT (and others, not considered in the current study) had been designed.