Cold-Crafted KNSu Mechanically Pressed Burning Rate for Combustion Pressure Ranging from 0.9 to 7.7 bar

Abstract

ABSTRACT Potassium nitrate/sucrose propellant (KNSu) is a common solid propellant, which can be cold or hot crafted, employed in amateur and experimental model rockets. There is limited burning rate data available for the KNSu, particularly for the cold-crafted one. In this study, KNSu composed of 65% potassium nitrate and 35% sucrose was prepared through cold crafting and by pressing with a hydraulic press. For such a particular crafting method, we did not find any experimental data on the burning rate versus combustion pressure. Therefore, we experimentally determined the cold-crafted KNSu burning rate for pressure levels ranging from 0.9 to 7.7 bar. We employed a ballistic evaluation motor with varying nozzle diameters to obtain the desired combustion pressure. We demonstrate that the cold-crafted KNSu burning rate lies in the range of available data for the hot-crafted version. The burning rate is not sensitive to combustion pressure levels lower than 2 bar, and the combustion temperature is 98.7% of the theoretical value. We also explain the estimation the combustion pressure from the thrust-plotted curve or by using the engine burning video.