A rocket catapult assembly for an ejection seat may comprise a motor assembly including a proximal end and a distal end, a first cartridge, and a second cartridge. The first cartridge and the second cartridge may be configured to provide a variable thrust based on an occupant's weight. The first cartridge may provide a thrust corresponding to a relatively light weight occupant, the second cartridge may provide a thrust corresponding to a relatively average weight occupant, and the first cartridge and second cartridge may provide a combined thrust corresponding to a relatively heavy weight occupant.