Conceptual Design And Seakeeping Optimization Research Of Small Launch Vehicle

Undoubtedly,space technology plays an important role in the national defense strategy and national economy of our country. Nowadays, the ground-launched rocket is predominant.Compared with land-based launch, sea launch has the various advantages in flexibility,Invisibility and economy. As a result, the sea-launched technology emerges in the engineers’mind gradually. There is no limitation in ballistic directions. The rotational linear velocity of the earth could be fully used to increase the carrying capacity of the rocket as well as the service life of the satellite. The launching cost could be reduced,either. Therefore, the explorations of the sea launch technology are significant for both military requirements and commercial rocket launch. The purpose of this thesis is to make conceptual design and optimization on the catamaran for the sea-launched rocket.In the process of determining the ship form, combined wind-wave-current impacts on the sea-based carrier is unstable. It will have a negative influence on the initial state,original alignment and the structure of rocket body. This thesis chooses alternative ship forms by comparing the sea-keeping performance of them. And then, we choose the catamaran with better combinational property, and then the calculation of primary design and monolithic property are conducted.The motion and structure response of rocket in the launch states depends upon the moment to the rocket itself, which is due to the sway of the carrier. Less amplitude of the sway will contributed to laughing. Therefore the moments impacted on the rocket affect the launching condition significantly. Based on the structural mechanical theory, the condition that rocket fixed on the sea-based carrier is simplified to a fixed elastic cantilever beam with one end setting free. The moment equations are obtained based on the calculation of rigid motion and elastic oscillation.Optimal model of the launching carrier’s sea-keeping performance is built by using the moment equations. The optimization variables were selected by analyzing the main parameters affecting on the sea-keeping performance. Then optimized constraint conditions are created based on the related information of rocket launch. This thesis selected the sample points with the method of Optimal Latin hypercube design (LHD) and calculated its sea-keeping performance and resistance. The data of sample points was expended with the method of quadratic interpolation. Then we create the Radical Basis Function(RBF) and search for the ship form with the best sea-keeping performance by Algorithm of Simulated Annealing (ASA)、Nonlinear Programming Quadratic Line search and Multi-Island Genetic Algorithm (MIGA) to meet the optimized constraint.