Enhancing combustion performance in KNSU solid rocket propellants: experimental study of coconut shell charcoal as a sustainable additive

Abstract

This study explores the incorporation of coconut shell charcoal (CSC), a sustainable biomass-derived carbon additive, into potassium nitrate-sucrose (KNSU) solid rocket propellants to enhance combustion performance. Experimental investigations were conducted on propellant formulations with varying CSC content (6% to 21% by weight), assessing their effects on burn rate, specific impulse, and thrust characteristics. Results demonstrate that CSC addition significantly reduces burn rate approximately 0.73 mm/s while simultaneously increasing specific impulse by 73.3%, compared to standard KNSU propellants. The unique porous structure and high carbon content of CSC contribute to modified combustion dynamics, higher adiabatic flame temperatures, and improved combustion efficiency. Additionally, CSC incorporation reduces propellant hygroscopicity, enhancing storage stability. These findings suggest that coconut shell charcoal is a promising eco-friendly additive for tailoring solid propellant performance, with potential applications in customized small-scale rocket motors for UAV propulsion and sustainable aerospace technologies utilizing agricultural waste.