Comparative Analysis of Solid Propellant Rocket Fuel Efficiency: Gunpowder vs. Sorbitol and Potassium Nitrate

Abstract

This research paper presents a detailed comparative analysis of the efficiency of two solid propellant rocket fuels: black powder and a sorbitol-potassium nitrate combination. The evaluation indicators adopted in the study include altitude, thrust, velocity, and trajectory in an effort to identify the most suitable fuel for small rockets. Both fuels were burned with identical rocket motors, each with a weight of 1,293 grams, to achieve an equal correlation in the combustion. The gunpowder fuel was formulated with the following composition: primarily, Potassium Nitrate (KNO₃) 65%, Activated Charcoal (C) 15%, and Sulfur (S) 10%; with Iron Oxide (Fe₂O₃) 2%, and Aluminum Powder for extra thrust at 8%. The final mixture of sorbitol and potassium nitrate was prepared in the ratio of 6:3:1 Parts, i.e., 60% Potassium Nitrate (KNO₃), 35% Sorbitol, and 5% Aluminum Powder were used to provide the best balance of oxidizer, fuel, and a small quantity of aluminum for enhanced burning. Two rockets were launched—one powered by gunpowder and the other by a sorbitol-potassium nitrate mixture. Both rockets were identical in construction, with a total length of 95.5 cm and a mass of 492 grams, not including the motor. They were designed for minimal weight, with a wooden cardboard nose cone, body, and fins. The position of the center of gravity (CG) was established at 69.7 cm from the base, while the center of pressure (CP) was at 53 cm, ensuring flight stability. A substantial amount of quantitative data, including altitude, thrust, velocity, and trajectory of the launch, were measured. The results, summarized in Table 1 (previously referred to as Fig. 2), demonstrate that the gunpowder-powered rocket achieved significantly higher altitude, thrust, and velocity, indicating superior efficiency compared to the sorbitol-potassium nitrate mixture.