During World War II, Wankel developed seals and rotary valves for German air force aircraft and navy torpedoes, for BMW and Daimler-Benz. After the war, he was imprisoned by France for some months in 1945 and his laboratory was closed by French occupation troops. Wankel's work was confiscated and he was prohibited from doing more work. However, by 1951, he got funding from the Goetze AG company to furnish the new Technical Development Center in his private house in Lindau on Lake Constance. He began development of the engine at NSU Motorenwerke AG, leading to the first running prototype on 1 February 1957. Unlike modern Wankel engines, this 21 horsepower version had both the rotor and housing rotating. His engine design was first licensed by Curtiss-Wright in New Jersey, United States.