Conceptual design methodology and tool for reusable single-stage-to-orbit vehicles with horizontal take-off and landing

To date, space launchers remain prohibitively expensive and the low reliability compared to commercial aircraft stands out as the main obstacles of future space exploration plans. To address these challenges, future launch vehicles necessitate a paradigm-shift towards more reusable and sustainable assets. In the current fast evolving landscape of competitive launch vehicle design, the development of a dedicated Reusable Launch Vehicle (RLV) design methodology becomes crucial. This thesis outlines the development steps towards an innovative sizing methodology for Single Stage to Orbit (SSTO) with Horizontal Takeoff and Horizontal Landing (HTOL) capabilities. Beginning with the elicitation of mission requirements, constraints, and assumptions, the methodology encompasses considerations such as vehicle geometry, propulsion strategy, and technological availability, thus defining conceptual configuration alternatives complemented by initial estimates of dimensions and performance to determine the technical feasibility of the planned mission. The iterative nature of this process aims at matching the hypothesized variables with the estimated ones, considering different Mach regimes, evaluating the thermal loads, and satisfying performance requirements across flight phases. During this highly iterative process, the definition of suitable propulsive configurations is critical to achieve the required thrust across different altitudes and minimizing propellant consumption. While this design procedure seeks convergence toward system volume and mass, a multiple-matching chart is developed to delineate the design space available for the chosen mission. With the idea of subsequently integrating a graphical user interface developed in Matlab environment, this work provides a complete methodology and toolbox that contributes to advancing the conceptual design phase of future launch vehicles, essential for realizing cost-effective and reliable access to space. Eventually, the methodology and the developed tool are applied to the case study of the SKYLON, a future reusable SSTO spaceplane developed by Reaction Engines Limited (REL), which exploits the Synergetic Air-Breathing Rocket Engine (SABRE) technology, a combined cycle engine able to cover the entire mission profile of the vehicle using liquid hydrogen as fuel.