An ornithopter (from Ancient Greek ὄρνις (órnis) 'bird' and πτερόν (pterón) 'wing') is an aircraft that flies by flapping its wings. Designers sought to imitate the flapping-wing flight of birds, bats, and insects. The term covers a wide range of possible designs. Ornithopters are typically built on the scale of the animals they emulate, however larger, crewed fliers have also found experimental success. Crewed ornithopters are generally powered either by engines or by the pilot.
Early history Some early crude flight attempts may have been intended to achieve flapping-wing flight, but probably only a glide was actually achieved. They include the purported flights of the 11th-century Catholic monk Eilmer of Malmesbury (recorded in the 12th century) and the 9th-century poet Abbas Ibn Firnas (recorded in the 17th century). Roger Bacon, writing in 1260, was also among the first to consider a technological means of flight. In 1485, Leonardo da Vinci began to study the flight of birds. He grasped that humans are too heavy, and not strong enough, to fly using wings simply attached to the arms. He, therefore, sketched a device in which the aviator lies down on a plank and works two large, membranous wings using hand levers, foot pedals, and a system of pulleys.
The first successful ornithopter was built by a Polish nobleman and scientist of Italian descent, Tytus Liwiusz Boratyni. In 1648, he built a spring-powered prototype that lifted a cat during a test flight. Tytus Boratyni planned to build a manned version called the "Flying Dragon". The project assumed numerous rescue systems, including a parachute. The bottom of the ornithopter's fuselage was to be able to float on water in the event of an accident over the sea or a lake. In order to implement the project, he unsuccessfully applied for funding for research from King Władysław IV Vasa. In 1841, an ironsmith kalfa (journeyman), Manojlo, who "came to Belgrade from Vojvodina", attempted flying with a device described as an ornithopter ("flapping wings like those of a bird"). Refused by the authorities a permit to take off from the belfry of Saint Michael's Cathedral, he clandestinely climbed to the rooftop of the Dumrukhana (import tax head office) and took off, landing in a heap of snow, and surviving. The first ornithopters capable of flight were constructed in France. Jobert in 1871 used a rubber band to power a small model bird. Alphonse Pénaud, Abel Hureau de Villeneuve, and Victor Tatin also made rubber-powered ornithopters during the 1870s. Tatin's ornithopter was perhaps the first to use active torsion of the wings, and apparently it served as the basis for a commercial toy offered by Pichancourt c. 1889. Gustave Trouvé was the first to use internal combustion, and his 1890 model flew a distance of 80 meters in a demonstration for the French Academy of Sciences. The wings were flapped by gunpowder charges activating a Bourdon tube. From 1884 on, Lawrence Hargrave built scores of ornithopters powered by rubber bands, springs, steam, or compressed air. He introduced the use of small flapping wings providing the thrust for a larger fixed wing; this innovation eliminated the need for gear reduction, thereby simplifying the construction.
E. P. Frost made ornithopters starting in the 1870s; first models were powered by steam engines, then in the 1900s, an internal-combustion craft large enough for a person was built, though it did not fly. In the 1930s, Alexander Lippisch and the National Socialist Flyers Corps of Nazi Germany constructed and successfully flew a series of internal combustion-powered ornithopters, using Hargrave's concept of small flapping wings, but with aerodynamic improvements resulting from the methodical study. Erich von Holst, also working in the 1930s, achieved great efficiency and realism in his work with ornithopters powered by rubber bands. He achieved perhaps the first success of an ornithopter with a bending wing, intended to imitate more closely the folding wing action of birds, although it was not a true variable-span wing such as those of birds. Around 1960, Percival Spencer successfully flew a series of uncrewed ornithopters using internal combustion engines ranging from 0.020-to-0.80-cubic-inch (0.33 to 13.11 cm3) displacement, and having wingspans up to 8 feet (2.4 m). In 1961, Percival Spencer and Jack Stephenson flew the first successful engine-powered, remotely piloted ornithopter, known as the Spencer Orniplane. The Orniplane had a 90.7-inch (2,300 mm) wingspan, weighed 7.5 pounds (3.4 kg), and was powered by a 0.35-cubic-inch (5.7 cm3)-displacement two-stroke engine. It had a biplane configuration, to reduce oscillation of the fuselage.
Crewed flight
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