Otto Lilienthal (1848-96), German inventor and aeronautical engineer, who was the first to demonstrate the advantage of curved surfaces for airplane wings. He studied aerodynamics, particularly the flight of birds, and by 1877 he had invented a glider with arched wings like a bird's. His first successful flight occurred in 1891. After making more than 2000 flights, he was killed when his glider crashed. He wrote Birdflight as the Basis of Aviation (1889; trans. 1911).