The dynamics associated with the jettisoning of a number of strap-ons from the parent launch vehicle is investigated. Three different models for the separation mechanisms are considered. Included in the analysis are forces due to the jettisoning mechanism along with the thrust on the core and the residual thrust on the strap-ons. Aerodynamic forces are, however, not considered. Geometry of collision in the multibody system is analyzed and three different criteria for detection of collisions are developed. The methodology is illustrated using two typical examples. The attitude motion of the controlled ongoing stage has been indirectly accounted for. Finally, a simple representation of the separation system is employed to construct a no-collision domain in the design parameter space.
Numerical investigations have been carried out to analyse the evolution of lunar circular orbits and the influence of the higher order harmonics of the lunar gravity field. The aim is to select the appropriate near-circular orbit characteristics, which extend orbit life through passive orbit maintenance. The spherical harmonic terms that make major contributions to the orbital behaviour are identified through many case studies. It is found that for low circular orbits, the 7th and the 9th zonal harmonics have predominant effect in the case of orbits for which the evolution is stable and the life is longer, and also in the case of orbits for which the evolution is unstable and a crash takes place in a short duration. By analysing the contribution of the harmonic terms to the orbit behaviour, the appropriate near-circular orbit characteristics are identified.
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