Methodology and tool to support the conceptual design of a reusable VTVL TSTO vehicle

In recent years, the advent of reusable launch systems has revolutionised the space sector, demonstrating not only their operational feasibility but also a significant reduction in cost per mission. Although these advanced systems are now dominated by developments in the United States, Europe is beginning to actively invest in the research and development of similar technologies, with the aim of building its capacity to access space in a sustainable manner. This thesis proposes an innovative design methodology, together with a supporting Python tool, for the rapid dimensioning of advanced expendable or reusable launch vehicles. The design tool developed is designed to be highly flexible, allowing rapid iteration from high level design and mission requirements. Within seconds, it will provide data on the size, mass, performance and mission profile of the selected launcher type. In this study, we focus on the investigation of a Two Stage to Orbit (TSTO) vehicle with Vertical Take-Off and Landing (VTVL). This type of architecture allows the reuse of the first stage, increasing operational sustainability and drastically reducing long-term costs. To validate the effectiveness of the proposed tool and methodology, the thesis includes an application study and results comparison on the case of RETALT1, a future reusable TSTO launcher currently under development in Europe. The use of the commercial software ASTOS allowed the validation of the mission analysis module by comparing the results of the developed methodology and replicating it within the software. The application of a tool such as ASTOS ensures that the results are robust and representative of the actual performance of the system. Finally, the study concludes by analysing the results obtained and outlining potential future developments of both the methodology and the tool.