Analysis of pneumatic catapult launch system parameters, taking into account engine and UAV characteristics

Abstract

Despite progress in the development of unmanned aerial vehicles (UAVs), universal launch systems are not currently used for them. In fact, each UAV project requires its own launcher, which is inefficient in many cases, especially for heavy UAVs weighing 50 kg or more, for which pneumatic launch systems are mainly used. To evaluate the characteristics of UAV launchers, simple methods are used at the level of analysis of acting forces, but they do not make it possible to correctly select the type and parameters of the catapult for specific tasks. In the absence of the necessary methods, this leads to design errors that significantly narrow the scope of the launcher. To eliminate these problems, a mathematical model of a pneumatic catapult has been developed, differential equations of motion and changes in the gas-dynamic parameters of structural elements have been compiled and numerically solved, an analysis of the structural scheme and basic parameters of the pneumatic launch system has been performed. It is shown by simulation that no special pneumatic cylinder piston sealing is required for the launcher's effective functioning, because at high air pressures leakage through the gap is controlled due to the short process time. Also, the permissible minimum height of the cable attachment point on the trolley above the block roller has been determined. The developed model confirmed the versatility of using the pneumatic launcher of the scheme under consideration for the UAVs with a take-off weight of 50 to 250 kg, and such a wide range is provided only by regulating the receiver air pressure and is not available for other types of systems. At the same time, the possibility of further increasing the takeoff weight of the UAV in the launch scheme under consideration will remain by increasing the diameter of the pneumatic cylinder.