A fixed-wing aircraft, commonly called an airplane or aeroplane, (from the Greek: aéros- "air" and -planos "wandering") and often shortened to plane,
is a heavier-than-air craft in which movement of the wings is not used
to generate lift. The term is used to distinguish airplanes from
rotary-wing aircraft, where the movement of the wing-surfaces generates
lift.
Fixed-wing aircraft include a large range of craft from small trainers
and recreational aircraft, to large airliners and military cargo
aircraft. The term also embraces aircraft with folding wings that are
intended to fold when on the ground. This is usually to facilitate
storage or transport. It also applies to "variable geometry" aircraft,
such as the General Dynamics F-111, the Grumman F-14 Tomcat, and the
Panavia Tornado, all of 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." Some aircraft use fixed
wings to provide lift only part of the time, and may or may not be
referred to as fixed-wing.
Two necessities for all fixed-wing aircraft are air flow over the wings
for lifting of the aircraft and an open area for landing. The majority
of aircraft, however, also need an airport with the infrastructure for
maintenance, restocking, refueling, and 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 taking off and landing on
aircraft carriers, ice, snow, and calm water.
The aircraft is the second fastest method of transport, after the
rocket. Commercial jet aircraft can reach up to 559 miles per hour.
Single-engined aircraft are capable of reaching 109 miles per hour or
more at cruise speed. Supersonic 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 the Antonov An-225
(Ukrainian), while the fastest currently in production is the Mikoyan
MiG-31 (Russian). The biggest supersonic jet ever produced and currently
in service is the Tupolev-160 (Soviet design).
Types of fixed-wing aircraft
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 miles at average speeds over
109 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.
Propeller aircraft
Smaller and older propeller aircraft make use of reciprocating internal
combustion engines that turn 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 economic on
shorter journeys.
Jet aircraft
First developed in England and Germany in 1931, jet aircraft make use of
turbines to create 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 use partly for that reason.
Jet aircraft possess high cruising speeds (300 to 400 mph) and high
speeds for take-off and landing (93 to 155 mph). Due to the speed needed
for takeoff and landing, jet aircraft make use of flaps and leading
edge devices for the control of lift and speed, and have engine
reversers (or thrust reversers) to direct the airflow forward, slowing
down the aircraft upon landing, in concert with the wheel brakes.
Wide-body aircraft, such as the Airbus A340 (French) and Boeing 777
(U.S.), can carry hundreds of passengers and several tons of cargo and
are able to travel for distances up to 10,563 miles.
Supersonic aircraft, such as military fighters and bombers, the Concorde
(French), and others, make use of special turbines (often utilizing
afterburners), that generate the huge amounts of power needed for flight
at faster than the speed of the sound.
The design problems for supersonic aircraft are substantially different
than those for subsonic 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, supersonic
aircraft are no longer used by major airlines.
Rocket-powered aircraft
Experimental rocket-powered aircraft were developed by the Germans as early as World War II,
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 (U.S.). The later North American X-15
(U.S.) 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 test vehicle for developing a
commercial sub-orbital passenger service; another rocket plane is the
XCOR EZ-Rocket; and there is of course NASA's Space Shuttle.
Ramjets and scramjets
The history of surface-launched, supersonic ramjet vehicles began
in 1944 at the request of the U.S. Navy's Bureau of Ordnance. In a
ramjet, is produced by passing the hot exhaust from the combustion of
fuel through a nozzle. The nozzle accelerates the flow and produces
thrust. To maintain the flow through the nozzle, high pressure
combustion is needed, which is accomplished by "ramming" external air
into the combustor, using the forward speed of the vehicle.
Scramjet is an short name for Supersonic Combustion Ramjet. The
scramjet differs from the ramjet in that combustion takes place at
supersonic velocities through the engine. It is mechanically simple, but
vastly more complex aerodynamically than a jet engine. Hydrogen is
normally the fuel used.
Both ramjet and scramjet aircraft are mostly in the experimental stage.
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 fifteenth 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.
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 August 28, 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 164 feet before
witnesses. In August 1892, Ader's Avion II flew for a distance of 656
feet, and on October 14, 1897, Avion III flew a distance of more than
984 feet. 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, because theirs was rather the first sustainable and well
documented flight. They made their first successful test flights on
December 17, 1903, and by 1905 their 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 on a flexing
mechanism called wing warpingfor stability. This was later superseded
by the development of ailerons, devices which performed a similar
function but were attached to an otherwise rigid wing.
Alberto Santos-Dumont a Brazilian living in France, built the first
practical dirigible balloons towards the end of the nineteenth century.
In 1906, he flew the first fixed-wing aircraft in Europe, the 14-bis,
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.
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 WWII, 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. Jet aircraft were first developed by both
the British and Germans during this period.
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 miles per hour.
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 until 2005, when it was surpassed by
the Airbus A380.
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 necessary due to the
increase in air traffic, particularly over urban areas, as noise
pollution is a major concern. The Massachusetts Institute of Technology
and Cambridge University have been designing delta-wing aircraft that
are 25 times more silent 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.
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
client.
Safety
Statistics show that the risk of an airliner accident is very small.
Although large scale crashes result in hundreds of fatalities, a study
of 583 airplane accidents between 1983 and 2000 showed that over 96
percent of those involved survived. However, most of these crashes did
not involve large passenger planes.
Environmental impact
Large aircraft have a strong 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. Environmental groups and the airline
industry make conflicting claims as to these effects.