Study On The Propulsion-aerodynamics-trajectory Integrated Optimal Design For Solid Ballistic Missile

The sort of solid ballistic missiles is the main constituent of military powerfor a big country, which also indicates the development trend of missiles forcoming several decades. So it will be an effective way of improving the militarypower to develop solid ballistic missiles.Generally, a missile’s most global performance has been determined in theconceptual design period. Therefore a better conceptual design could layfoundation for the best global performance and we should try our best to obtainthe optimal design result in this design period. In order to get the optimal design,propulsion system design, aerodynamic shape design and trajectory design are allconsidered in this paper so that their mutual influence will be taken into accountduring the conceptual design. So this paper focuses on the propulsion,aerodynamics and trajectory integrated design.This paper is divided into three parts. Firstly, three mathematical models ofpropulsion system, aerodynamic shape and missile trajectory are given which canprovide some fundamental characteristics of each subsystem. Then according tothe expected performance demand, the initial design result of three subsystems isgotten through missile trajectory optimization theory and design principles ofballistic missile. Finally, the initial design result is optimized through theoptimization theory. In this section, the global mathematical model foroptimization is built and simplified which involves multiple variables and tens ofconstraints. And the improved PSO is used here to get the optimal design result.In detail, the velocity when the missile’s propulsion system turns off can beestimated based on missile trajectory optimization theory. On the basis ofZiolkovsky formula, the Lagrangian multiplier method would offer the optimalmass value of each stage of missile. The global mathematical model foroptimization includes twenty nine variables and thirty two constraints. When theuniform design method is utilized to analyze this global model, nine constraint sare cut off and only twenty three are left. Considering the specific nature of thismodel, several improvements about the constraints disposal in PSO are given.These improvements can avoid the particle swarm’s premature and enhance thecalculation efficiency. The initial positions of all particles are provided by the uniform design table which can enlarge the coverage of initial particles, increasethe variety of particles and advance the search efficiency of PSO. Simulationresult shows that the optimal design result can satisfy all constraints and theinitial mass of missile is less than1000kg.