Low-overload internal ballistics in UAV ejection using multiple time-sequenced compressed-air chambers

Compressed-air ejection systems are characterized by short actuation times and high instantaneous flow rates, which subject unmanned aerial vehicles (UAVs) to significant overloads during launch. These conditions impose stringent structural requirements on UAVs, adversely affecting weight and cost control. To achieve a high launch velocity with low overload, this study proposes a multi-chamber ejection method with time-sequenced actuation. This approach is based on an internal ballistics model that incorporates real-gas properties. This approach reduces launch overload while maintaining the required muzzle velocity. An internal ballistics model for UAV compressed-air ejection has been developed and experimentally validated, utilizing real-air properties. Furthermore, a multi-chamber ejection strategy was introduced. Simulations were conducted to analyze the internal ballistic performance of systems with two or three identical or different high-pressure chambers. The results demonstrate that using multiple chambers significantly reduces the maximum overload-by 20.91%, 26.08%, and 33.24% for two identical, two different, and three different chambers, respectively-while achieving the same muzzle velocity as a single-chamber system.