Ariane 5 and beyond?

Plans for the development of launch vehicles by ESA for the 1990s and beyond are surveyed, with a focus on the A-5 project at CNES. The HM60 large cryogenic engine (a derived-flux design with nominal vacuum thrust 900 kN and specific impulse 443 sec) planned for operational status in 1992 is described; the three proposed configurations for the A-5 (one based on the A-4, one using solid-fuel boosters with an HM60 main stage, and one purely cryogenic version using an H170 main stage) are compared; and development strategies for a future launching system involving recoverable first stages and/or boosters are discussed. Drawings and diagrams are provided, and definitive decisions on the course of development are predicted for 1985 to permit development starting in 1986-1987 and operational status by 1995.