Fixed-wing aircraft
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A fixed-wing aircraft is a heavier-than-air craft where movement of the wings in relation to the aircraft is not used to generate lift. The term is used to distinguish from rotary-wing aircraft, or ornithopters, where the movement of the wing surfaces relative to the aircraft generates lift. Modern aeroplanes may reach well over 500 mph while flying and take off at roughly 180 mph.
Fixed-wing aircraft are commonly called airplanes in North America (the U.S. and Canada), and aeroplanes in Commonwealth countries (other than Canada) and Ireland. These latter terms are derived from Greek aéros- ("air") and -planos ("wandering"). Both terms are often shortened to just planes.
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[edit] Overview
Fixed-wing aircraft include a large range of craft from small training and recreational aircraft to large airliners and military cargo aircraft. Some aircraft use fixed wings to provide lift only part of the time and may or may not be referred to as fixed-wing.
The term also embraces aircraft with folding wings that are intended to fold when on the ground. This is usually to ease storage or facilitate transport on, for example, a vehicle trailer or the powered lift connecting the hangar deck of an aircraft carrier to its flight deck. It also embraces "variable geometry" aircraft, such as the General Dynamics F-111, Grumman F-14 Tomcat and the Panavia Tornado, which can vary the sweep angle of their wings during flight. There are also rare examples of aircraft which can vary the angle of incidence of their wings in flight, such the F-8 Crusader, which are also considered to be "fixed-wing".
Two necessities for all fixed-wing aircraft (as well as rotary-wing aircraft) are air flow over the wings for lifting of the aircraft (Bernoulli's Principle), and an open area for landing. The majority of aircraft, however, also need an airport with the infrastructure to receive maintenance, restocking, refueling and for the loading and unloading of crew, cargo and/or passengers. While the vast majority of aircraft land and take off on land, some are capable of take off and landing on ice, snow and calm water.
The aircraft is the second fastest method of transport, after the rocket. Commercial jet aircraft can reach up to 900 km/h. Single-engined aircraft are capable of reaching 175 km/h or more at cruise speed. Supersonic aircraft (military, research and a few private aircraft) can reach speeds faster than sound. The speed record for a plane powered by an air-breathing engine is currently held by the experimental NASA X-43, which reached nearly ten times the speed of sound.
The biggest aircraft currently in service is Antonov An-225, while the fastest currently in production is the Mikoyan MiG-31. The biggest supersonic jet ever produced and currently in service is Tupolev-160.
[edit] Types of fixed-wing aircraft
[edit] Gliders
Gliders or sailplanes are aircraft designed for unpowered flight. Most gliders are intended for use in the sport of gliding and have high aerodynamic efficiency: lift-to-drag ratios may exceed 70 to 1. The energy for sustained gliding flight must be obtained through the skillful exploitation of naturally occurring air movements in the atmosphere. Glider flights of thousands of kilometres at average speeds over two-hundred kilometres per hour have been achieved.
Military gliders have been used in war for delivery of assault troops, and specialized gliders have been used in atmospheric and aerodynamic research. Motor gliders equipped with engines (often retractable), some capable of self-launching, are becoming increasingly common.
[edit] Propeller aircraft
Smaller and older propeller aircraft make use of reciprocating internal combustion engines that turns a propeller to create thrust. They are quieter than jet aircraft, but they fly at lower speeds, and have lower load capacity compared to similar sized jet powered aircraft. However, they are significantly cheaper and much more economical than jets, and are generally the best option for people who need to transport a few passengers and/or small amounts of cargo. They are also the aircraft of choice for pilots who wish to own an aircraft.
Turboprop aircraft are a halfway point between propeller and jet: they use a turbine engine similar to a jet to turn propellers. These aircraft are popular with commuter and regional airlines, as they tend to be more economical on shorter journeys.
[edit] Jet aircraft
Jet aircraft make use of turbines for the creation of thrust. These engines are much more powerful than a reciprocating engine. As a consequence, they have greater weight capacity and fly faster than propeller driven aircraft. One drawback, however, is that they are noisy; this makes jet aircraft a source of noise pollution. However, turbofan jet engines are quieter, and they have seen widespread usage partly for that reason.
The jet aircraft was developed in England and Germany in 1931. The first jet was the Heinkel He 178, which was tested at Germany's Marienehe Airfield in 1939. In 1943 the Messerschmitt Me 262, the first jet fighter aircraft, went into service in the German Luftwaffe. In the early 1950s, only a few years after the first jet was produced in large numbers, the De Havilland Comet became the world's first jet airliner, but was removed from service due to structural inadequacies discovered after numerous pressurization and depressurization cycles.
Wide-body aircraft, such as the Airbus A340 and Boeing 777, can carry hundreds of passengers and several tons of cargo, and are able to travel for distances up to 17 thousand kilometers.
Jet aircraft possess high cruising speeds (700 to 900 km/h, or 400 to 550 mph) and high speeds for take-off and landing (150 to 250 km/h). Due to the speed needed for takeoff and landing, the jet aircraft makes use of flaps and leading edge devices for the control of lift and speed, and has engine reversers (or thrust reversers) to direct the airflow forward, slowing down the aircraft upon landing, as well as the wheel brakes.
[edit] Supersonic jet aircraft
Supersonic aircraft, such as military fighters and bombers, Concorde, and others, make use of special turbines (often utilizing afterburners), that generate the huge amounts of power for flight faster than the speed of the sound. The design problems for supersonic aircraft are substantially different to those for sub-sonic aircraft.
Flight at supersonic speed creates more noise than flight at subsonic speeds, due to the phenomenon of sonic booms. This limits supersonic flights to areas of low population density or open ocean. When approaching an area of heavier population density, supersonic aircraft are obliged to fly at subsonic speed.
Due to the high costs, limited areas of use and low demand there are no longer any supersonic aircraft in use by any major airline. The last Concorde flight was on 26 November 2003. It appears that supersonic aircraft will remain in use almost exclusively by militaries around the world for the foreseeable future, though research into new civilian designs continues.
[edit] Rocket-powered aircraft
Experimental rocket powered aircraft were developed by the Germans as early as World War II (see Me 163 Komet), although they were never mass produced by any power during that war. The first fixed wing aircraft to break the sound barrier in level flight was the rocket powered Bell X-1. The later North American X-15 was another important rocket plane that broke many speed and altitude records and laid much of the groundwork for later aircraft and spacecraft design. Rocket aircraft are not in common usage today, although rocket-assisted takeoffs are used for some military aircraft. SpaceShipOne is the most famous current rocket aircraft, being the testbed for developing a commercial sub-orbital passenger service; another rocket plane is the XCOR EZ-Rocket; and there is of course the Space Shuttle.
[edit] Ramjet aircraft
Ramjet aircraft are mostly in the experimental stage. The D-21 Tagboard was an unmanned Mach 3+ reconnaissance drone that was put into production in 1969 for spying, but due to the development of better spy satellites, it was cancelled in 1971. The SR-71's Pratt & Whitney J58 engines ran 80% as ramjets at high-speeds (Mach 3.2). The SR-71 was dropped in the early 70's and then brought back during the cold war. They were used also in the gulf war. The last SR-71 flight was in October 2001.
[edit] Scramjet aircraft
Scramjet aircraft are in the experimental stage. The Boeing X-43 is an experimental scramjet with a world speed record for a jet-powered aircraft - Mach 9.6, nearly 12,000 km/h (≈ 7,000 mph) at an altitude of about 36,000 meters (≈ 110,000 feet). The X-43A set the flight speed record on 16 November 2004.
[edit] History
The dream of flight goes back to the days of pre-history. Many stories from antiquity involve flight, such as the Greek legend of Icarus and Daedalus. Leonardo da Vinci drew an aircraft in the 15th century. With the first flight made by man (Francois Pilatre de Rozier and Francois d'Arlandes) in an aircraft lighter than air, a balloon, the biggest challenge became to create other craft, capable of controlled flight.
[edit] First attempts
Sir George Cayley, the inventor of the science of aerodynamics, was building and flying models of fixed-wing aircraft as early as 1803, and he built a successful passenger-carrying glider in 1853. In 1856, Frenchman Jean-Marie Le Bris made the first powered flight, by having his glider "L'Albatros artificiel" pulled by a horse on a beach. On 28 August 1883, the American John J. Montgomery made a controlled flight in a glider. Other aviators who had made similar flights at that time were Otto Lilienthal, Percy Pilcher and Octave Chanute.
Self-powered aircraft were designed and constructed by Clément Ader. On October 9, 1890, Ader attempted to fly the Éole, which succeeded in taking off and flying a distance of approximately 50 meters before witnesses. In August 1892 the Avion II flew for a distance of 200 metres, and on October 14, 1897, Avion III flew a distance of more than 300 metres. Richard Pearse made a poorly documented uncontrolled flight on March 31, 1903 in Waitohi, New Zealand, and on August 28, 1903 in Hanover, the German Karl Jatho made his first flight.
The Wright Brothers are commonly credited with the invention of the aircraft[1], but like Alexander Graham Bell's telephone, theirs was rather the first sustainable and well documented attempt. They made their first successful test flights on December 17, 1903 and by 1905 Flyer III was capable of fully controllable, stable flight for substantial periods. Strictly speaking, the Flyer's wings were not completely fixed, as it depended for stability on a flexing mechanism named wing warping. This was later superseded by the development of ailerons, devices which performed a similar function but were attached to an otherwise rigid wing. This was the first manned flight.
Alberto Santos-Dumont a Brazilian living in France, built the first practical dirigible balloons from the end of the nineteenth century. In 1906 he flew the first fixed wing aircraft in Europe, the 14-bis, which was of his own design. It was the first aircraft to take off, fly and land without the use of catapults, high winds, or other external assistance. A later design of his, the Demoiselle, introduced ailerons and brought all around pilot control during a flight. Santos-Dumont is put forward as the true inventor of the aircraft, but owing to the competing claims, the concept of the invention of the first flying machine has substantial ambiguity.
Wars in Europe, in particular World War I, served as initial tests for the use of the aircraft as a weapon. First seen by generals and commanders as a "toy", the aircraft proved to be a machine of war capable of causing casualties to the enemy. In the first world war, the fighter "aces" appeared, of which the greatest was the German Manfred von Richthofen, commonly called the Red Baron. On the side of the allies, the ace with the highest number of downed aircraft was René Fonck, of France.
After the First World War, aircraft technology continued to develop. Alcock and Brown crossed the Atlantic non-stop for the first time in 1919, a feat first performed solo by Charles Lindbergh in 1927. The first commercial flights took place between the United States and Canada in 1919. The turbine or the jet engine was in development in the 1930s; military jet aircraft began operating in the 1940s.
Aircraft played a primary role in the Second World War, having a presence in all the major battles of the war, especially in the attack on Pearl Harbor, the battles of the Pacific and D-Day, as well as the Battle of Britain. They were also an essential part of several of the military strategies of the period, such as the German Blitzkrieg or the American and Japanese Aircraft carriers.
In October 1947, Chuck Yeager, in the Bell X-1, was the first recorded person to exceed the speed of sound. However, some British Spitfire pilots claimed to have exceeded Mach 1 in a dive. The Boeing X-43 is an experimental scramjet with a world speed record for a jet-powered aircraft - Mach 9.6, or nearly 7,000 mph.
Aircraft in a civil military role continued to feed and supply Berlin in 1948, when access to railroads and roads to the city, completely surrounded by Eastern Germany, were blocked, by order of the Soviet Union.
The first commercial jet, the de Havilland Comet, was introduced in 1952. A few Boeing 707s, the first widely successful commercial jet, are still in service after nearly 50 years. The Boeing 727 was another widely used passenger aircraft, and the Boeing 747, was the biggest commercial aircraft in the world up until 2005, when it was surpassed by the Airbus A380.
[edit] Designing and constructing an aircraft
Small aircraft can be designed and constructed by amateurs as homebuilts. Other aviators with less knowledge make their aircraft using pre-manufactured kits, assembling the parts into a complete aircraft.
Most aircraft are constructed by companies with the objective of producing them in quantity for customers. The design and planning process, including safety tests, can last up to four years for small turboprops, and up to 12 years for aircraft with the capacity of the A380.
During this process, the objectives and design specifications of the aircraft are established. First the construction company uses drawings and equations, simulations, wind tunnel tests and experience to predict the behavior of the aircraft. Computers are used by companies to draw, plan and do initial simulations of the aircraft. Small models and mockups of all or certain parts of the aircraft are then tested in wind tunnels to verify the aerodynamics of the aircraft.
When the design has passed through these processes, the company constructs a limited number of these aircraft for testing on the ground. Representatives from an aviation governing agency often make a first flight. The flight tests continue until the aircraft has fulfilled all the requirements. Then, the governing public agency of aviation of the country authorizes the company to begin production of the aircraft.
In the United States, this agency is the Federal Aviation Administration (FAA), and in the European Union, Joint Aviation Authorities (JAA). In Canada, the public agency in charge and authorizing the mass production of aircraft is Transport Canada.
In the case of the international sales of aircraft, a license from the public agency of aviation or transports of the country where the aircraft is also to be used is necessary. For example, aircraft from Airbus need to be certified by the FAA to be flown in the United States and vice versa, aircraft of Boeing need to be approved by the JAA to be flown in the European Union.
Quieter aircraft are becoming more and more needed due to the increase in air traffic, particularly over urban areas, as noise pollution is a major concern. MIT and Cambridge University have been designing delta-wing aircraft that are 25 times more silent (63dB) than current craft and can be used for military and commercial purposes. The project is called the Silent Aircraft Initiative, but production models will not be available until around 2030.[2]
[edit] Industrialized production
There are few companies that produce aircraft on a large scale. However, the production of an aircraft for one company is a process that actually involves dozens, or even hundreds, of other companies and plants, that produce the parts that go into the aircraft. For example, one company can be responsible for the production of the landing gear, while another one is responsible for the radar. The production of such parts is not limited to the same city or country; in the case of large aircraft manufacturing companies, such parts can come from all over of the world.
The parts are sent to the main plant of the aircraft company, where the production line is located. In the case of large aircraft, production lines dedicated to the assembly of certain parts of the aircraft can exist, especially the wings and the fuselage.
When complete, an aircraft goes through a set of rigorous inspection, to search for imperfections and defects, and after being approved by the inspectors, the aircraft is tested by a pilot, in a flight test, in order to assure that the controls of the aircraft are working properly. With this final test, the aircraft is ready to receive the "final touchups" (internal configuration, painting, etc), and is then ready for the customer.
[edit] Safety
Statistics show that the risk of an airliner accident is very small, so small that the chance of having an accident while driving to the airport in a car is higher than having an accident during the flight. Many people have a fear of flying because they erroneously believe that the risk of death in the event of an aircraft accident is extremely high, when in fact a study of 583 accidents between 1983 and 2000 show that over 96% of those involved survived.[1] Furthermore, car crashes rarely feature outside local news whereas air crashes are reported internationally, making the risk seem greater.
Aircraft are the second safest way to travel long distances after railway trains. The per-trip safety of aircraft is somewhat safer than cars, but over the long distances aircraft cover, they are much safer than other types of transport.
The majority of aircraft accidents are a result of human error on the part of the pilot(s) or controller(s). After human error, mechanical failure is the biggest cause of air accidents, which sometimes also can involve a human component; e.g., negligence of the airline in carrying out proper maintenance. Adverse weather is the third largest cause of accidents. Icing, downbursts, and low visibility are often major contributors to weather related crashes. Birds have been ranked as a major cause for large rotor bursts on commercial turboprop engines, spurring extra safety measures to keep birds away. Technological advances such as ice detectors also help pilots ensure the safety of their aircraft.
[edit] Environmental impact
Aircraft have a particularly marked impact on the environment, compared with other commonly used vehicles. Their contrails contribute to global dimming, and their noise is often significant. However, the most significant impact of such aircraft upon the environment is their contribution of greenhouse gases. They are responsible for emitting a great deal of carbon monoxide and nitrogen dioxide, and they distribute the gases more evenly on a global level and far higher in the atmosphere than any other commonly used vehicle type.
[edit] See also
[edit] References
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This article or section may use words or ideas of other works in its text without citing sources. Using citations to support claims outside the realm of elementary knowledge helps guard against copyright violations and factual inaccuracies. Please improve the article or discuss this issue on the talk page. Help on using footnotes is available. This article has been tagged since December 2006. |
- Blatner, David. The Flying Book : Everything You've Ever Wondered About Flying On Airplanes. ISBN 0-8027-7691-4
[edit] External links
- Aircraft-info.net
- Airliners.net
- Virtual Aircraft Museum
- Jetphotos.net
- How Airplanes Work - Howstuffworks.com
