French approach in future launch systems

Abstract Reduction of launch costs for crews and payloads in low Earth orbit is a basic objective of the post-Ariane 5 generation of space transportation systems. Recoverable vehicles is the most obvious solution, provided their refurbishment does not prove too costly. These systems feature larger uncertainties than expendable vehicles due to the extra weight to be carried into orbit for performing re-entry. Hence, the useful load becomes a smaller fraction of the gross weight while the uncertainties on the latter increase. Along these lines, CNES has initiated coordinated basic studies on system and propulsion: System studies by Aerospatiale compare concepts of reusable vehicles combining horizontal and vertical take-off, single-stage and two-stage configurations and various propulsion modes. Another system studied by AMD-BA aims at building a data-base through a conservative project using available proven data and performs parametric studies to evaluate the sensitivity of the concept to technological changes. In the propulsion field, SNECMA, SEP and ONERA examine a wide spectrum of combined engines in order to select the more promising for space plane propulsion. The paper gives the present state of these studies which will be terminated in late 1988.