Graziano & Raulin
Research Methods (9th edition)
Otto Lillienthal (1848-1896) was a German aeronautical engineer and inventor, who published an important book, Bird Flight as the Basis of Aviation, in 1889. Using that work as his theoretical base, he then empirically tested his ideas by designing, constructing, and flying his own gliders.
Lillienthal had more than 2000 successful heavier-than-air flights in gliders years before the Wright brother’s first flights. Although balloonists had been flying successfully since the late 1700s, Lillienthal was the first person in history to achieve heavier-than-air flight, completing some flights of 800 feet.
Just prior to his death in a glider crash in 1896, Lillienthal had been working on plans for a powered airplane, using the new gasoline engines.