Ornithopter subclass of powered aircraft
Crewed flight
Crewed ornithopters fall into two general categories: Those powered by the muscular effort of the pilot (human-powered ornithopters), and those powered by an engine.
Around 1894, Otto Lilienthal, an aviation pioneer, became famous in Germany for his widely publicized and successful glider flights. Lilienthal also studied bird flight and conducted some related experiments. He constructed an ornithopter, although its complete development was prevented by his untimely death on 9 August 1896 in a glider accident.
In 1929, a man-powered ornithopter designed by Alexander Lippisch (designer of the Messerschmitt Me 163 Komet) flew a distance of 250 to 300 metres (800–1,000 ft) after tow launch. Since a tow launch was used, some have questioned whether the aircraft was capable of flying on its own. Lippisch asserted that the aircraft was actually flying, not making an extended glide. (Precise measurement of altitude and velocity over time would be necessary to resolve this question.) Most of the subsequent human-powered ornithopters likewise used a tow launch, and flights were brief simply because human muscle power diminishes rapidly over time.
In 1942, Adalbert Schmid made a much longer flight of a human-powered ornithopter at Munich-Laim. It travelled a distance of 900 metres (3,000 ft), maintaining a height of 20 metres (65 ft) throughout most of the flight. Later this same aircraft was fitted with a three-horsepower (2.2 kW) Sachs motorcycle engine. With the engine, it made flights up to 15 minutes in duration. Schmid later constructed a 10-horsepower (7.5 kW) ornithopter, based on the Grunau-Baby IIa sailplane, which was flown in 1947. The second aircraft had flapping outer wing panels.The French engineer René Riout devoted himself for three decades to the realization of flapping wing ornithopters. In 1905 he invented his first models. In 1909 he won the gold medal in the Lépine competition for a reduced model. In 1913 he worked on the development of a model ordered by a pilot, the Dubois-Riout. The tests were stopped in 1916. In 1937, he finalized the Riout 102T Alérion, certainly the most successful piloted flapping wing ornithopter until the second decade of the 21st century. Unfortunately, the conclusions of the wind tunnel tests were not favorable to the continuation of the project.
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