Conceptual design of a VTOL spacecraft aimed at parabolic flights

This paper deals with the conceptual design of a VTOL spacecraft aimed at performing parabolic flights for both touristic and scientific purposes. In a very preliminary phase, different solutions arose from a brainstorming activity but only few of them seem to be respectful of the different constraints imposed by the stakeholders, the environment, the short Time-To-Market and of the existing flight rules and the in-development recommendations. Taking into account stakeholders' needs, constraints and requirements, a system engineering approach has been applied to derive the main functions this vehicle shall perform and possible sets of subsystems able to accomplish them. In particular, in order to reach 100 km of altitude, after a departure with air-breathing engines, to be in accordance with stakeholders' national flight rules, a complex propulsion system is sketched. It consists of two air-breathing engines able to allow a Harrier-like vertical lifting phase and the final steering manoeuvres during the descent path and a liquid rocket engine able to perform the most demanding segment of the parabola-ascending path. Complementary, rocket engine and relative propellant tanks are sized in order to guarantee the climbing performance allowing the spacecraft to reach the target altitude. Apart from the propulsion subsystem, all other subsystems have also been considered, even though particular attention is devoted to those subsystems whose architecture, size and location deeply affect the spacecraft layout. Crew compartment and cabin escape system are also properly addresse