Preliminary design of reusable future space access vehicles

The space economy can only thrive if reliable, responsive and economical access to space is granted by the launch industry. The competitive spur at the turn of the millennium has started numerous endeavours attempting to capture shares of the launch market, providing alternative solutions with different value propositions. These new, innovative, launch vehicles, deviating from the more classical architectures and CONOPS, require complicated, multidisciplinary evaluations of their performances to enable analyses and trade-offs from the early design phases to guide the development. These added complexities are even more pronounced for reusable, lifting body vehicles with multiple or combined-cycle engine types, where the aerodynamics, propulsion, and trajectory influence each others. This work provides a methodology to perform mission analysis from the concept of a project onwards, integrating a flexible simulator structure in a trajectory optimisation framework with MDO capabilities suitable for the early phase vehicle sizing. The whole stack is designed to be readable, modular, and flexible, accepting the different levels of fidelity available at each milestone of the project time-line. A direct, multiple shooting transcription enables the use of discontinuous datasets with rapid model integration. The breakdown of the trajectory in multiple sub-arcs, and the multi start approach provide a stable framework able to converge and identify solutions from wide searchspaces, even when the analyst cannot provide an initial guess. The approach presented is validated with a suite of standardised trajectory optimisation test cases, and applied to a range of problems exploring all the different phases that a reusable lifting body vehicle might encounter during nominal and off-nominal operations. The methodology can be employed from the analysis of the commercial viability of a concept to the trajectory design for mission and safety analysis required for regulatory framework compliance.The space economy can only thrive if reliable, responsive and economical access to space is granted by the launch industry. The competitive spur at the turn of the millennium has started numerous endeavours attempting to capture shares of the launch market, providing alternative solutions with different value propositions. These new, innovative, launch vehicles, deviating from the more classical architectures and CONOPS, require complicated, multidisciplinary evaluations of their performances to enable analyses and trade-offs from the early design phases to guide the development. These added complexities are even more pronounced for reusable, lifting body vehicles with multiple or combined-cycle engine types, where the aerodynamics, propulsion, and trajectory influence each others. This work provides a methodology to perform mission analysis from the concept of a project onwards, integrating a flexible simulator structure in a trajectory optimisation framework with MDO capabilities suitable for the early phase vehicle sizing. The whole stack is designed to be readable, modular, and flexible, accepting the different levels of fidelity available at each milestone of the project time-line. A direct, multiple shooting transcription enables the use of discontinuous datasets with rapid model integration. The breakdown of the trajectory in multiple sub-arcs, and the multi start approach provide a stable framework able to converge and identify solutions from wide searchspaces, even when the analyst cannot provide an initial guess. The approach presented is validated with a suite of standardised trajectory optimisation test cases, and applied to a range of problems exploring all the different phases that a reusable lifting body vehicle might encounter during nominal and off-nominal operations. The methodology can be employed from the analysis of the commercial viability of a concept to the trajectory design for mission and safety analysis required for regulatory framework compliance