German aeronautical engineer who designed the first successful helicopter flown in 1936. The autogyro, a hybrid airplane-helicopter, was introduced in 1920 by Spanish engineer Juan de la Cierva. However, the craft was difficult to maneuver. Focke's design, a twin-rotor aircraft, was stable and easier to maneuver. In 1924 he and George Wulf started an aircraft company building a variety of civil and military aircraft including the helicopter. After World War II he taught aeronautical engineering at the Technical University in Stuttgart, Germany.