This is an aircraft that flies by flapping its wings, much like a bird or insect. Flapping wing flight is one of the most tried and true methods for becoming airborne; nature has after all been doing it for many millions of years. Trying to reproduce the method artificially has proven difficult at best.
This article mostly concerns large, advanced ornithopters that can more or less match the performance of modern-day subsonic aircraft. Though ornithopter technology can eventually offer somewhat greater efficiency and maneuverability than most types of airplanes or helicopters, the alternates to it are easier to engineer and will likely remain cheaper for quite some time. Ornithopters therefore have an uphill battle if they are ever to be developed for wide-spread use; technologies already exist which can do what they can do, and the advantages they offer might not be enough to overcome both the economics and cultural momentum of using other types of aircraft. However, in the more distant future (or on alternate science-fiction worlds) where advanced materials and engineering techniques are more readily available than today, ornithopters may come into their own.
When humans first started trying to create flying machines, ornithopters were their most natural early attempts. Leonardo Da Vinci himself drew up plans for one, and many early pioneers of heavier-than-air flight in the nineteenth and twentieth centuries tried their hand at the technology, usually with less than spectacular results. Gustave Trouve flew the first true successful ornithopter, a small model one, in the 1870s. Adelbert Schmidt flew the first confirmed manned, engine-powered ornithopter in 1942. A human-powered ornithopter was flown by a team from the University of Toronto Institute for Aerospace Studies in 2010.
A number of small, unmanned, remote-controlled ornithopters already exist, and many flight enthusiasts consider them a worthwhile hobby. A few modern manned ornithopters have been built and flown. Ornithopters are also occasionally seen in science fiction. They were featured in the Dune series of novels by Frank Herbert and in a number of anime
films by director Hayao Miyazaki, particularly Castle in the Sky.
An ornithopter flies by imitating the motion of the wings of birds. Some small ornithopters are based on the workings of insect wings, but for the most part insect wing flight does not scale up very well and are considered for use only on small robot toys and drones.
Bird flight depends both on the shape of the wing as well as forward motion to provide flight, much like in normal airplanes. The wing is shaped so that the bird’s forward motion through the air provides lift to the underside of the wing. Near the bird’s body, the wing does not move very much over all, and most of the lift is provided there. Near the outer edges of the wing, the wing tip is designed to curve or warp, so it cuts neatly through the air on the upstroke but catches the air and pushes it backward on the downstroke.
An ornithopter attempts to duplicate this complex motion. Artificial wings are either moved up and down, or rotated in a tight pattern, with the wing near the plane’s body moving only slightly with each wingstroke and the wingtips curling or turning as needed to push the air backward for forward motion. Unlike with birds, the entire wing need not twist, but rather certain outer gimballed or jointed sections may do so.
Two major problems have always bedeviled the development of practical manned ornithopters; wing designs that can efficiently handle both lift and twisting of the wingtip sections for forward thrust, and materials that handle the stresses on the wings and wing joints at the flapping speeds needed to sustain flight. The latter is very important; in order to lift heavy loads, the wings would have to flap fairly fast and handle a huge amount of stress, especially on take off and landings.
Modern computer-optimized designs combined with sophisticated materials such as advanced composites, carbon fibers, and graphene have made workable manned ornithopters a reality. However, the performance of these vehicles still lags considerably behind other types of modern aircraft, and they will likely be many decades catching up. For now they’re mostly just aeronautical curiosities.
Once perfected, manned ornithopters are theorized to be both somewhat more maneuverable and more energy-efficient than airplanes. Because their lift and propulsion is combined in the same structures (the wings,) they have less overall drag. Their flapping wings are also able to manipulate a larger volume of air around the vehicle, compared to the relatively thin streams of air created by an airplane’s propellers, allowing for more overall control. Very advanced ornithopters may have very versatile wings that may even allow the craft to hover, using similar wing-motions to that of hummingbirds.
One area where ornithopters may see widespread practical use is in unmanned drones, used by the military, research foundations, and other organizations. Their greater efficiency would mean being able to get more flight time out of a given power supply, and their greater maneuverability could serve the operators well in scouting out dangerous and complicated terrain at relatively low altitude, such as an unknown jungle or an enemy urban zone.
Once large-scale ornithopters are a perfected technology, it may be possible to combine them with features of other aircraft to increase performance in certain areas. For example, an advanced ornithopter would be prized for high maneuverability, but there are times when speed may be more important. In this case, a hybrid may mount auxiliary means of propulsion, such as a rear-mounted pusher propeller or even jet engines. The wings would lock in place and its back-up engines would engage, converting it into a more conventional, higher-speed aircraft for the duration.
http://www.ornithopter.org/http://ornithopter.net/index_e.html http://www.theregister.co.uk/2010/09/23/pedalo/ http://www.daviddarling.info/encyclopedia/O/ornithopter.html http://en.wikipedia.org/wiki/Ornithopter
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