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

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.

KEYWORDS:

• KNSu
• rocket engine
• solid propellant
• burning rate
• nozzle

Acknowledgments

We would like to acknowledge José Osmar Klein Jr and Lucas Schlossmacher for their support. We would also like to acknowledge the PRH, DEMEC, CAPES/PRÓ-ESTRATÉGIA, Ceramics Laboratory, LabMetro, and Canguiri farm for their support. We thank the reviewer of this work for his comments and suggestions.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors acknowledge the Department of Mechanical Engineering of Federal University of Paraná (UFPR), the Uniespaço Program of the Brazilian Space Agency (AEB), and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil, for the physical and financial support given for this work. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil, Finance Code 001. The first author receives a scholarship supported by CNPq.