Mono- and Bipropellants Based on Nitrous Oxide and Fuels: State of the Art, Recent Developments in Academia and Industry, and a Special Focus on DLR’s Activities

The chapter gives an overview on the research and development activities regarding mono- and bipropellants based on nitrous oxide and fuels. Nitrous oxide-based propellants offer significant advantages compared to conventional toxic and carcinogenic propellants, e.g., easy handling, non-toxicity, low cost, and good availability. Initially, an overview of so-called premixed monopropellants is given. Here, nitrous oxide and different fuels are stored premixed in a single tank. Therefore, a monopropellant-like system with a bipropellant performance is obtained. During numerous test activities with this kind of propellants, the explosive characteristic and the safe use of such propellants remain a major focus of the research activities. In the second part of the chapter, an overview on nitrous oxide/fuel bipropellants is given. These propellants offer low cost, good availability, safe handling, and self-pressurized propulsion systems while avoiding the explosion hazards of the premixed propellant. Several companies across the globe investigate nitrous oxide fuel bipropellants, and the available technology has a different degree of maturity. The current development focus is on thruster improvement to achieve a long term as well as reliable operation. Furthermore, due to the propellant properties, propulsion system components have to be newly developed and qualified. Due to the advantages of nitrous oxide-based propulsion, it is perfectly suitable for the New Space market.