Development and Characterization of Alternative, Environmentally Friendly Solid Propellants Based on Renewable Sugars and Low- Toxicity Oxidants for Aerospace Applications

The current commercial solid propellants for experimental rocketry are based on barium nitrate, ammonium perchlorate and black powder among others, all of which present potential toxicity. Besides, diphenylamine, an additive to avoid deterioration of nitrocellulose, is likely carcinogenic, and solid or liquid particles are deposited in the respiratory tract depending on their size, in addition to gaseous by-products such as SO ₂ and NO _x that threaten environmental health. The main objective of this study was to develop a safe solid propellant, maintaining safety standards, aiming at sustainability by reducing the toxicity of solid propellant combustion. For our solid propellant SP1, we maintained a ratio of 65% anhydrous D-glucose to 35% potassium nitrate, with ferric oxide and calcium carbonate as oxidant. Thermochemical analysis was performed by Cantera simulation platforms, confirming that SP1 produces cleaner combustion than current commercial propellants, with CO ₂ , H ₂ O and N ₂ as main products, as well as few NO _x emissions (< 5%), and no halogenated by-products. Combustion temperature was in the range 1430–1730°C, ignition temperature in the range 180–200°C, specific impulse in the range 120–140s, calorific value in the range 3.5–4.5 MJ/kg, and combustion velocity in the range 3–10 mm/s. Combustion simulation performed with ANSYS Mechanical, Open Rocket and MATLAB supported the predictions on fluid dynamics, structural integrity and flight. Laboratory tests were also performed to validate the results, calorimetry and combustion velocity. Data measurement and collection of thrust was performed on a static test bench, and a modelling of gas emissions was subsequently performed. The propellant exhibited low sensitivity to impact and friction, as well as moderate hygroscopicity, thermal stability at 180°C and a shelf life of 12 months without moisture. Safe handling, low production cost and accessibility to raw materials show that SP1 is an interesting, secure and efficient alternative for experimental rocketry, CubeSat and aerospace platforms.