ZEHST: environmental challenges for hypersonic passenger transport

The ZEHST hypersonic transport airplane, derived from Astrium Space Plane concept, and having roots in a French-Japanese cooperation, was unveiled by EADS at Paris Air Show 2011. In the frame of a DGAC (French Civil Aviation Authority) sponsoring, EADS Innovation Works together with MBDA, Astrium and Onera launched a feasibility and system study to set up the detailed requirements, assess the technologies envisioned and perform a first design loop, based on shortterm availability of technologies. The 3-propulsion-system concept comprises turbofans for subsonic operations, rocket engines to cross the transonic regime and ramjet engines for efficient high-speed cruise. ZEHST stands for Zero Emission High Speed Technologies, thus emphasizing the will to take into account environmental footprint while designing the vehicle and its trajectory. The aim of the activities on environmental impact within the ZEHST program, for which Onera is responsible, is to set up a methodology highlighting the phenomenology to be taken into account, selecting the appropriate models to compute significant metrics, and conducting trade studies and assessments to provide design guidelines to the conceptual design team. This paper will illustrate this methodology with selected examples among sonic boom, rocket noise and particle emissions assessments.