 Although several prototypes were built and ready for state tests, Lyulka was forced to abandon his research and evacuate to the Ural mountains as the Great Patriotic War began with the Nazi invasion of the Soviet Union.In 1941-42, Lyul'ka worked in a tank factory in Chelyabinsk as a Diesel-engine engineer.However, after the failure of the Soviet rocket engine project of 1942, Joseph Stalin recalled Arkhip Lyul'ka among other scientists working on jet engines to resume their work in Moscow.