The Oberursel UR-2 rotary engine, rated at 110 horsepower, was the type used to power the Fokker Dr.1 Triplane. Built by the Oberursel Motoren Gesellschaft of Frankfurt, Germany, it was an exact copy of the famous French LeRhone 110-horsepower rotary engine. The UR-2 from von Richthofen's airplane is on display at the Imperial War Museum, London, England. This UR-2 is one of the very few others still in existence.