New multidisciplinary design optimization approaches for launch vehicle design

Launch vehicle design is a complex problem involving a series of disciplines. These disciplines present conflicting objectives and require multidisciplinary design optimization methods in order to handle the couplings and to make the search of compromises easier. Launch vehicle design problem is a specific multidisciplinary design optimization problem because it combines the optimizations of design and trajectory variables. In this article, we present a new multidisciplinary design optimization approach, called the StageWise decomposition for Optimal Rocket Design (SWORD). This method splits up the multidisciplinary design optimization process into different stages and transforms the initial multidisciplinary design optimization problem into the coordination of elementary ones. This method is compared to the standard multidisciplinary design optimization method (multidiscipline feasible method). In this article, we propose a new formulation of the SWORD method and a new dedicated optimization strategy. Results show that using a global search algorithm, the stagewise decomposition for optimal rocket design method allows to find a better optimum than multidiscipline feasible method. Furthermore, with the new proposed optimization strategy, the SWORD method does not require any initialization from the user, allows to quickly find feasible solutions and converge to an optimum in a limited computation time.