Ornithopter

An ornithopter (from Greek ornithos "bird" and pteron "wing") 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 scaled-up, person-carrying ornithopters have also been built.

Early history

Although there are earlier fanciful accounts of humans flying with artificial wings (such as the ancient Greek tale of Icarus), the first person in the Western tradition to propose a mechanical ornithopter seems to have been Roger Bacon. ^[1]

A more serious attempt was made c.1490, when Leonardo da Vinci began to study the flight of birds. 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. He only ever made a small scale model of an ornithopter.

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. It is believed today that Meerwein's ornithopter most likely glided after launching from a higher place. ^[2]

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).

Piloted flight

File:Schmid.1new.jpg Many attempts at piloted ornithopter flight have been made, only a few of which have been successful. In 1929 Alexander Lippisch, in Germany, glided in a human-powered ornithopter, but it had to be towed into the air, and did not achieve true flight. In 1959 Emil Hartman, in England, also managed the same feat after being towed into the air.

Adalbert Schmid developed a motorized, human-carrying aircraft propelled by a set of small flapping wings and sustained with a large fixed wing, which reportedly 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.

A team at the University of Toronto Institute for Aerospace Studies, headed by professor James DeLaurier, worked for many years on an engine-powered, piloted ornithopter. On July 8 2006 at Downsview Park in Toronto Professor DeLaurier's ornithopter sustained flight for about a third of a kilometre for 14 seconds ^[3], having made a jet-assisted takeoff. The brief sustained flight concluded with a damaging landing due to localized buckling along the left wing.^[4]

Modern practical applications

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. Ornithopters 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.

Because ornithopters resemble birds, they could theoretically be used for military applications, such as spying without alerting the enemy that they are under surveillance.

Aerodynamics

Aerodynamically, ornithopters differ from fixed wing aircraft in that the driving airfoils have a reciprocating, rather than rotary, motion.

Typically, the driving airfoils are large, so that the volume of air acted on to produce thrust is maximized. Since the flapping airfoils may produce both lift and thrust, drag-inducing structures are minimized. These two advantages may allow ornithopters to achieve a high degree of efficiency in flight.

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 since the ornithopter body typically oscillates counter to the wing motion.

In fiction

In the movie Ghost in the Shell 2: Innocence the characters used an ornithopter to visit the ocean city.
The ornithopter (called "'Thopter") is familiar to readers of Frank Herbert as the primary means of on-planet travel by the wealthy inhabitants of the Dune universe. This is a theme also carried into the Dune computer games: Dune, 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 original movie didn't even have wings at all. The 'Dune Encyclopedia' 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.
In The Brother's War, a novel based on Magic: The Gathering, the fictional characters Urza and Mishra used ornithopters invented by the Thran to move between places. Recent flavor texts for the Ornithopter states that, regardless of plane, artificers always 'invent' Ornithopters first. The game also contains a card representing an ornithopter as a flying artifact creature. 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," in reference to the Ornithopter's natural inability to deal damage. Finally, variations of the ornithopter have been introduced in the game.
Ornithopter-like craft called "moths" are carried aboard the Lexx and can travel in air or space.
In Robert Heinlein's novel Number of the Beast, ornithopters are used for long-distance travel by the Russian and British colonists of an alternate-universe Mars.
Ornithopters are a means of transportation used by the Dark Empire in The History of the Runestaff series of novels by Michael Moorcock.
The retro film Sky Captain and the World of Tomorrow features ornithopters in dog fights against fixed-wing aircraft.
The fantasy novels Airborn (novel) and Skybreaker (novel) 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.
In Hayao Miyazaki's interpretation of the Diana Wynne Jones book, the film Howl's Moving Castle, all the flying craft are ornithopters, although they are not referred to as such. The craft range from the smaller, which have two wings which flap like a hummingbirds, to the larger military craft that have 14 main wings and multiple smaller wings all flapping in concert.
Ornithopters have also appeared in two other shorts done by Studio Ghibli that have been shown at Studio Ghibli Museum's Saturn Theatre.
Imaginary Flying Machines is an animated short about the various contraptions dreamed up by people over the ages, which includes ornithopters. Directed, written and narrated by Hayao Miyazaki.
The Ornithopter Story: Fly to the Sky Hiyodiro Tengu!, is a short documentary about the efforts of Hiyodiro Tengu, a famous model airplane maker, to build a remote controlled model ornithopter.

References

External links

[1] Aeragon article on Roger Bacon

[2] wiseGEEK article on Ornithopter

[3] Toronto Star article on The Flapper's 2006 flight

[4] Dr. James DeLaurier's report on the Flapper's July 8, 2006 Flight

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