First-stage design variations of partially reusable launch vehicles

Different types of reusable first stages designed for a near-term application with heavy lift launchers are investigated. The attached reference expendable space transportation system is a future Ariane 5 with cryogenic core and upper stage but skipped solid rocket boosters. The design of the so-called liquid flyback boosters is restricted to the incorporation of powerful hydrogen or hydrocarbon rocket motors already under development or in operation. The analyzed layout variants of the reusable vehicle include single- as well as dual-booster configurations. Catamaran-type double fuselage stages are investigated to evaluate the potential in reducing the unsymmetrical thrust load of one-side-mounted booster. Along with their primary use to boost heavy lift geostationary transfer-orbit missions, a second task may be covered by the same vehicle to accelerate the upper stages of small and medium launchers. The additional design requirements in such a dual-use reusable launch vehicle are studied. The investigation includes trajectory simulations and optimizations for ascent, as well as an assessment of propellant requirements and vehicle loads during return flight to the launch site. Critical flight stability aspects are evaluated by static and dynamic simulations. A comparison of size and mass is included, as well as performance data of the different liquid flyback booster configurations. The relevant rocket engine figures of performance, mass, reusability, and throttling capability are presented.