Ascent trajectory design of small-lift launch vehicle using hierarchical optimization

An integrated algorithm to design the optimal ascent trajectory of a target Sun-synchronous orbit (SSO) for small-lift launch vehicles is studied in this paper. A general problem description is provided, including the specific pitch law designed for an ascent trajectory to SSO and the definitions of design variables and equality/inequality constraints. Then an integrated optimization scheme is introduced to solve this problem. In order to improve its efficiency, a preliminary determination method is to analytically generate two sensitive design variables related with the coast arc. With the help of the two design variables, an initial combination of design variables can be obtained by solving separately the optimization problems of two powered phases. Based on the predetermination method, an efficient integrated algorithm using hierarchical optimization is proposed. A simulation based on a type of small-lift Electron Rocket and Rutherford engine is performed using this hierarchical optimization algorithm and the feasibility and efficiency of this algorithm is evaluated. These systematic investigations on all the possible injected orbits give a full detail of launching capability for Electron Rocket.