Analysis of the Ariane 62/64 and Vega-C launcher family

After the French minister in charge of space matters declared to be open to discuss about Ariane 6 design changes in Mai 2014, several new concepts have been proposed by the industry and analysed by agencies including DLR during the whole summer 2014. Discussions between the different actors at agency level (ESA, CNES, DLR, ASI) and at industry level led to the development of a new Ariane 6 launcher, with a PHH architecture, which was officially agreed upon on December 2nd, 2014 in Luxemburg at the ESA council at ministerial level. The present work describes the analyses performed independently within the DLR group XTRAS to critically assess the so-called A62/A64 concepts. The chosen architecture of Ariane 62/64 is similar to the one of Ariane 5. The first stage uses cryogenic propellants LOX/LH2 and a low cost evolution of Vulcain 2: Vulcain 2.1. It differs from the Ariane 5 EPC by a smaller propellant loading and separate tanks with the aim of reducing manufacturing costs. The upper stage also uses LOX/LH2 and is propelled by the Vinci engine in a slightly modified configuration: the deployment system of the nozzle is no longer considered and the nozzle is shortened, as cone C has been removed and cone B is directly fixed on cone A. The architecture of the upper stage also considers separate tanks, in order to limit the production cost and to remove difficulties linked to propellant management during ballistic phases, which had been identified as a critical point for the upper stage of Ariane 5 ME. One additional feature of Ariane 6 is that the launcher is modular. It is equipped with 2 or 4 solid rocket motors for the version named Ariane 62 and Ariane 64 respectively. These motors are named P120C. This motor should also be used as first stage on the next evolution of Vega: Vega-C. Consequently Vega-C is also shortly considered in the frame of this report. While the first analysis (for instance the sensitivity presented in this report) are based on early concepts of Ariane 62/Ariane 64, more detailed analyses presented considered Ariane 62/Ariane 64 in its July 2015 status. According to the high level requirements Ariane 62 should be able to launch 5 tons to GTO and Ariane 64 should be able to launch 10.5 tons to GTO. Note that at the moment this report is being written, the final configuration of Ariane 62/64 is not frozen and might still vary. The cost aspect is also part of the analyses presented in this report. In addition, to trajectory and costs, structural analysis, liquid rocket engine considerations, solid rocket motor design, controllability, transient aerodynamic and thermal aspects are also treated