Aerodynamic Analysis of the Dual-Mode Ramjet Vehicle JAPHAR

Summary

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 in–flight performance demonstration is developed [1]. 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 in order to cover both regimes, subsonic and supersonic combustion. The main objective of the vehicle is to provide realistic specifications for the different components of the propulsion system. It 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 paper focusses on the aerodynamic analysis of the main design drivers of the vehicle which are the available thrust, longitudinal trim, longitudinal stability and the transition between the flight modes.