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Ornithopter

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Edward Frost of Cambridgeshire, England, constructed an ornithopter of willow, silk, and feathers in 1902

An ornithopter is an aircraft that flies by wing-flapping. Since many examples of wing-flapping flight exist in nature such as birds, bats, and insects, designers of Ornithopters seek to imitate this mode of flight. Ornithopters are usually built on the same scale as these flying creatures, though some overscale, manned ornithopters have also been built.

History

Man has long dreamed of flying like the birds, but it wasn't until about 1490 that Leonardo da Vinci studied the flight of birds seriously. He grasped that human beings are too heavy, and not strong enough, to fly using unaided arms and legs alone.

He proposed an ornithopter having two rocking beams with large flaps driven by the arms and legs working in unison. He also drew a sketch of a more advanced 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.

In 1781 Karl Friederich Meerwein is supposed to have succeeded in flying in an ornithopter at Giessen in Germany, demonstrating that, by applying a large amount of power to a machine of lightweight construction, it should be possible to fly in a heavier-than-air craft.

In 1799 the English physicist George Cayley formulated most of the aerodynamic theory of flight, after which ornithopters were mostly abandoned in favour of gliders.

The first ornithopters capable of flight were constructed in France in the 1870s. They were powered by rubber band or, in one case, by gunpowder charges activating a bourdon tube, which flapped the wings (Gustav Trouvé, 1870).

In 1929 Alexander Lippisch, in Germany, flew in a human-powered ornithopter, but it had to be towed into the air, and then glided. In 1959 Emil Hartman, in England, also managed the same feat after being towed into the air.

Many attempts at manned ornithopter flight have been made, only a few of which have been successful. Adalbert Schmid developed a motorized, manned ornithopter that made extended flights in 1942 (Weltluftfahrt, March 1950, p. 195). From 1990-1995, Vladimir Toporov and students built a tow-launched ornithopter that reportedly could be made to climb as a result of the pilot's muscular effort. Currently (as of 2004), a team at the University of Toronto's Institute for Aerospace Studies, headed by professor James DeLaurier, is working on an engine-powered, manned ornithopter designed to take off unaided.

The present

Practical applications for ornithopters capitalize on their resemblance to bird flight. The Colorado Division of Wildlife has used ornithopters to help save the endangered Gunnison Sage Grouse. Ornithopters resembling birds of prey cause the grouse to remain on the ground so they can be captured for study. Ornithopers can also be used to drive flocks of birds away from airports, where they pose a safety hazard. AeroVironment, Inc., led by Paul B. MacCready (Gossamer Albatross), has developed a remotely piloted ornithopter the size of a large insect for possible spy missions. As demonstrated by birds, flapping wings offer potential advantages in maneuverability and energy savings compared with fixed-wing aircraft.

MacCready also developed, for the Smithsonian Institution, a half-scale replica of the giant pterosaur, Quetzalcoatlus northropi. The model had a wingspan of 5.5 meters (18 feet) and featured a complex, computerized control system, just as the full-size pterosaur relied on its neuromuscular system to make constant adjustments in flight.

Ornithopters are also built and flown by hobbyists. These range from light-weight models powered by rubber band, to larger, radio control ornithopters. Current designs stem from Percival Spencer's engine-powered ornithopters, developed circa 1958, and Sean Kinkade's work in the late 1990s. Electric motors or piston engines provide the power to flap the wings.

A research project by Georgia Tech scientist Robert C. Michelson is developing a Reciprocating Chemical Muscle for use in micro-scale aircraft with flapping wings called the Entomopter. SRI International is developing polymer artificial muscles for use in ornithopters and other applications.

Aerodynamics

Aerodynamically, ornithopters differ from fixed wing aircraft in that they generate both lift and thrust using a flapping wing. This is generally performed by rotating the wing during a flapping cycle such that the force vector normal to the wing has a force component in the forward direction that is large enough to exceed the drag of the aircraft.

The use of the same surfaces for lift and propulsion has the fundamental advantages that drag-inducing structures are minimized while the volume of air acted on to produce thrust is maximized. Alexander Lippisch appears to have held this point of view.

From general aerodynamic considerations, ornithopters appear to make more efficient use of power than rotating propeller or jet aircraft do. The difficulties that have prevented major practical application appear to be the required mechanisms and structures, and the comfort of passengers.

The ornithopter (called "'Thopter") is familiar to readers of Frank Herbert as the primary means of on-planet travel by the inhabitants of the Dune universe. This a theme also carried into the Dune related games: Dune II, Dune 2000, Emperor: Battle for Dune, and Frank Herbert's Dune. Oddly, in neither the Dune movie nor the SciFi channel TV miniseries were the 'thopters depicted with flapping wings. The 'thopters in the movie didn't have wings at all. 'The Encyclopedia of Dune' entry on the 'thopter depicts them as being powered by giant, airbreathing, bivalve shelled animals.

Ornithopters are also mentioned in the book Norstrilia by Cordwainer Smith. This is one of many similarities between Norstrilia and Dune (albeit a minor one).

Ornithopter-like craft called "moths" are carried aboard the Lexx and can travel in air or space.

The retro film Sky Captain and the World of Tomorrow features ornithopters in dog fights against fixed-wing aircraft.

The Magic: The Gathering card game also contains a card representing an ornithopter as a flying artifact creature, which costs 0 to play (one of the 6 zero cost creatures) and is a 0/2, therefore dealing 0 damage in combat. Some early rules texts for the game (from around the period of Revised) include the humorous line in small text near the end: "We apologize to anyone that has been killed by an ornithopter." This would be possible (using effects to increase the damage the Ornithopter deals, for example), but a rare death indeed. The most recent flavor texts for the Ornithopter states that, regardless of plane, artificers always 'invent' Ornithopters first.

The fantasy novels Airborn and Skybreaker by Kenneth Oppel use ornithopters as short-distance flying machines.

Ornithopters are featured in Star Wars: Revenge of the Sith, as a means of transportation on the Wookiee homeworld, Kashyyyk.

Wikimedia Commons has media related to Category:Ornithopter.
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