RAMS APPROACH FOR REUSABLE LAUNCH VEHICLE ADVANCED STUDIES

The emerging of reusable single stage to orbit concept as credible lau nchers in the turn of the century is changing some technical and techn ological approaches in the way of doing future launcher advanced studi es. Among others (such as operations through the ''aircraft-like opera tions'' concept), the RAMS approach (reliability. availability. mainta inability and safety) has to be implemented from the very beginning of a concept study, especially for the SSTOs ones in order to meet the ' 'able'' requirements (affordable, reusable, reliable, available and op erable). Beyond the ''traditional'' considerations applied to expendab le launchers and/or man rated space transportation systems, the RAMS i nvolvement in reusable launcher advanced studies and concept trade-off s must allow to perform the best balance between costs, performance an d related risks. For instance, in the frame work of SSTOs key technolo gies identification studies performed at Aerospatiale, the RAMS have b een involved from the beginning of the preliminary design task. This a pproach has shown that the assessment of the main propulsion failure r isks and associated probabilities of occurrence have strongly affected the vehicle design within the mission management and technical aspect s such as main propulsion specifications, ascent trajectory shaping an d landing phase scenario (VTOVL configuration). This paper intends to describe this RAMS approach and addresses how it has been applied on I rade-off on VTOVL concept. (C) 1998 Elsevier Science Ltd. All rights r eserved.