Design and performance analysis of an electrically controlled solid rocket motor: Variable-thrust and repeated-operation characteristics

To overcome the limited restart capability and narrow throttling range of conventional solid rocket motors, a proof-of-concept electrically controlled solid rocket motor (ECSRM) based on electrically controlled solid propellant (ECSP) was designed and experimentally evaluated. The prototype employed an axial parallel-electrode configuration with a porous molybdenum anode, a thin cathode, and an integrated ceramic insulation/thermal-protection structure to satisfy electric-field loading, gas discharge, and high-temperature insulation requirements. Experiments were conducted to evaluate controllable start-stop behavior, steady-state thrust regulation, step-voltage response, and cyclic operation. The motor achieved controllable ignition and extinction over 150–350 V. At 200 V, the thrust rise and decay times were 683.5 ± 59.2 ms and 357.0 ± 50.3 ms, respectively. As the applied voltage increased, the average thrust rose from 1.07 ± 0.43 N to 4.77 ± 0.31 N, corresponding to a thrust throttling ratio of 4.46, with a pronounced nonlinear thrust-voltage relationship. The actual performance approached the theoretical value as chamber pressure increased. Cyclic tests achieved eight start-stop cycles, although tail-off and stronger fluctuations appeared in later cycles. SEM/EDS indicated that composite deposits and local pore blockage were likely responsible for performance drift and stability deterioration.