Nitrous oxide
German rocket scientists were experimenting with nitrous oxide fuel blends as early as 1937. Nitrous oxide fuel blends testing continued throughout World War II. The promise of high performance, greater range and lighter feed systems drove experimentation with blends of nitrous oxide and ammonia, which resulted in numerous explosions and demolished motors. The complexities involved in building propulsion systems that can safely handle nitrous oxide fuel blend monopropellants have been a deterrent to serious development.