Characteristics of Dynamic Loads Acting on an Extendible Nozzle

An extendible nozzle is considered to be a feasible device to improve the performance of booster engines because it has possibilities to provide altitude compensation and to achieve higher specific impulse. The booster engine with the extendible nozzle has to deploy its extendible nozzle during firing. The loads acting on the extendible nozzle vary with a nozzle deployment position as well as an altitude. For the design of the extendible nozzle and its driving mechanics, it is required to clarify the characteristics of dynamic loads acting on the extendible nozzle. In order to investigate the characteristics of dynamic loads, firing tests were carried out on a high altitude test stand. The extendible nozzle was sustained by a nozzle supporting system composed of six rods, and the nozzle deploying position was adjusted at 100%, 76%, and 56% deployed position. In the firing tests, the ambient pressure was varied to simulate an altitude change. The axial load and side load acting on the extendible nozzle were evaluated quantitatively by using small load cells installed in each supporting rod. From the experimental data of dynamic loads acting on the extendible nozzle for 100%, 76%, and 56% deployed position, the effect of nozzle deployment position on the dynamic loads were clarified.