In this study, in terms of the exercise vehicles of the weapon systems having negative buoyancy, the analysis on the operation concepts was performed and the new methods of floating to surface were proposed. In case of having negative buoyancy, the additional methods for recovering the exercise vehicle have to be considered. As parts of recovering the exercise vehicle, for floating to surface the new methods of weight discharge, weight separation and sea water discharge were proposed. The conceptual design about sea water discharge method was performed. It was confirmed that those methods could be applied to the design of the exercise vehicle having negative buoyancy.

The effect of the ignition delay time gap is newly studied. The operational characteristics of the linked two pyrotechnic thrusters are affected by the time gap. Although two thrusters are simultaneously ignited, the time at which the pressure starts to rise in each thruster may not be synchronized. The characteristic of the system with the time gap is compared with that of the fully synchronized system without any time gap. Depending upon the magnitude of the time gap, the pressure-time profile and the ballistic performance are different. When two pyrotechnic thrusters have a time gap, the peak pressure of one thruster(in which the pressure is built up earlier) is increased and the other is decreased. As the time gap is increased, the peak pressure is converged into the maximum pressure. This maximum pressure can be obtained when only one thruster is activated. Because the maximum pressure is bounded, it is predicted that there isn't any catastrophic failures in the considered system. When the time gap is relatively small, the impulse of the combined force acting on the moving body is almost maintained. But the ballistic performance of the system with a large time gap should be carefully estimated because the reduction of the ballistic performance should not be easily neglected.