Studies of Small-Scale Biofuel Rocket Propulsion

Abstract

Small satellites such as CubeSats have become increasingly popular among researchers and are being launched at an increasingly high frequency. The growth of small satellite technology has created a demand for novel small propulsion systems. Aviation-grade liquid biofuels offer a sustainable, safe, and relatively cheap replacement to other aerospace fuels and can be used as a kerosene replacement for bipropellant rocket engines. To investigate whether a small-scale, biofuel-burning bipropellant engine can be used as a propulsion solution onboard small satellites, a test 1 N rocket motor was designed to burn biofuel and gaseous oxygen. The motor was fabricated from titanium and was supported by a propellant feed system and a test stand apparatus that collected pressure, temperature, and thrust force data to evaluate the motor's performance with various conventional and biofuel propellants. Upon testing, the rocket motor was first evaluated with several gaseous fuels. The motor lacked a reliable internal ignition system and was sized too small, so only gaseous acetylene could be successfully burned in the rocket motor chamber. This problem precluded testing with the liquid biofuels. However, the issues that appeared during testing indicated that the motor should be enlarged, making its usefulness onboard small satellites, which have tight mass and volume requirements, increasingly unlikely. Nevertheless, liquid biofuels still have a strong potential to replace kerosene in larger bipropellant rocket motors, so future research should shift its focus to launch vehicle applications.