Design Studies of the JAPHAR Experimental Vehicle for Dual Mode Ramjet Demonstration

Within the DLR - ONERA cooperation JAPHAR (Joint Airbreathing Propulsion for Hypersonic Application Research), the feasibility of a dual mode ramjet engine, combining subsonic and supersonic combustion, is investigated and a methodology for on-ground and inflight performance demonstration is developed. The studies are organised around the blue-print of the experimental vehicle JAPHAR (Fig. 1) which is considered to fly between M = 4 and M = 8. This allows to cover both regimes, subsonic and supersonic combustion. The vehicle provides a solid context and realistic specifications for the different components of the propulsion system. It also answers to one of the fundamental peculiarities of airbreathing propulsion, which is the high level of integration between vehicle and propulsion system requiring a strongly coupled design. This is important not only to establish the propulsive balance but also to obtain a realistic estimation of the component performances. The given paper focusses on the aerodynamic analysis of the main design drivers of the vehicle which are the available thrust, longitudinal trim, longitudinal stability. With view to the application of small leading edge bluntnesses the assessment of the heat loads based on a fluid-structure coupling is presented