Re-entry trajectory optimization for a SSTO vehicle in the presence of atmosheric uncertainties

Pescetelli, Fabrizio and Minisci, Edmondo and Brown, Richard (2013) Re-entry trajectory optimization for a SSTO vehicle in the presence of atmosheric uncertainties. In: 5th European Conference for Aeronautics and Space Sciences, EUCASS, 2013-07-01 - 2013-07-04.

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    Abstract

    This paper addresses the design of the unpowered re-entry trajectory of a fully reusable, winged, unmanned single-stage-to-orbit (SSTO) vehicle, as the last phase of a payload deployment into low Earth orbit. A hybrid optimisation technique that couples a population-based, stochastic algorithm with a deterministic, gradient-based technique is used to minimize the heat load along the re-entry trajectory after accounting for operational constraints on the heat flux and normal acceleration. Uncertainties in the atmospheric model are considered to evaluate their eects on the vehicle performance. Firstly, the deterministic optimal control law is re-integrated after introducing uncertainties into the model. The proximity of the final solutions to the target states are analysed statistically. A second analysis is then performed, aimed at determining the best performance of the vehicle when these uncertainties are included directly in the optimisation. The statistical analysis of the results so obtained are summarized by an expectancy curve which represents the probable vehicle performance as a function of the uncertain system parameters. This analysis can be used during the preliminary phase of design to yield valuable insights into the robustness of the performance of the vehicle to uncertainties in the specification of its parameters.