Abstract: Aiming at the problem of insufficient functional power of traditional pneumatic catapult medium air, it is proposed to use carbon dioxide as a new catapult medium. Based on the law of mass conservation and energy conservation, the pneumatic catapult thermodynamic model with carbon dioxide as the catapult medium is established, and the effects of carbon dioxide and air as the catapult medium on the catapult performance are analyzed using the model. The dynamic change process of the medium state in the high and low pressure chambers and the movement parameters of the aircraft during the catapult process are obtained. Compared with air, carbon dioxide has greater power. Using carbon dioxide to eject aircraft of the same mass under the same thermal state can achieve a greater exit speed. The aircraft with a larger mass can fully utilize the power of carbon dioxide, and the load mass can be increased by more than 50% with the use of carbon dioxide without decreasing the exit speed. The feasibility of carbon dioxide as a working medium for pneumatic catapult is verified.

Key words: Pneumatic catapult, Carbon dioxide, Real gas effect