Airplane

An airplane (American English), or aeroplane (Commonwealth English), also plane, is a fixed-wing aircraft that is pushed forward by thrust from a jet engine, propeller, or rocket engine. Airplanes come in many sizes, shapes, and wing configurations. They are used for recreation, transportation of goods and people, military purposes, and research.

Around the world, commercial aviation carries more than four billion passengers each year on airliners. It also moves more than 200 billion tonne-kilometers of cargo each year, which is less than 1% of the world's cargo movement. Most airplanes are flown by a pilot on board, but some are designed to be remotely or computer-controlled, such as drones.

The Wright brothers invented and flew the first airplane in 1903. Their flight was recognized as "the first sustained and controlled heavier-than-air powered flight." They built on the work of George Cayley, who set out the concept of the modern airplane in 1799 and later built and flew models and successful passenger-carrying gliders. They also built on the work of German pioneer of human aviation Otto Lilienthal, who studied heavier-than-air flight between 1867 and 1896. Lilienthal's flight attempts in 1891 are seen as the beginning of human flight.

After its limited use in World War I, aircraft technology continued to develop. Airplanes were present in all the major battles of World War II. The first jet aircraft was the German Heinkel He 178 in 1939, and the first jet airliner, the de Havilland Comet, was introduced in 1952. The Boeing 707, the first widely successful commercial jet, was in commercial service for more than 60 years, from 1958 to 2019.

This article is about the aircraft. For the comedy film, see Airplane!. For other uses, see Airplane (disambiguation). "Aeroplane" redirects here. For other uses, see Aeroplane (disambiguation).

Etymology and usage

The word airplane was first used in English in the late 1800s, before the first powered flight. Like aeroplane, it comes from the French word aéroplane. That word combines the Greek word for "air" with either the Latin word for "level" or a Greek word meaning "wandering." At first, aéroplane referred only to the wing, which is a plane moving through the air. Through synecdoche, a way of using a part to mean the whole, the word for the wing came to mean the whole aircraft.

In the United States and Canada, "airplane" is used for powered aircraft with fixed wings. In the United Kingdom, Ireland, and most of the Commonwealth, people usually say "aeroplane." According to the Oxford English Dictionary, "airplane" became the standard U.S. term, replacing "aeroplane," after the National Advisory Committee for Aeronautics adopted it in 1916.

History

Main articles: Aviation history and First flying machine

Many old stories tell of flight, such as the Greek legend of Icarus and Daedalus, and the Vimana in ancient Indian epics. Around 400 BC in Greece, Archytas was said to have built a bird-shaped flying model that was pushed forward by a jet of what was probably steam. Early gliders were tried by Abbas ibn Firnas and Eilmer of Malmesbury. Leonardo da Vinci studied bird wings and designed a man-powered aircraft in his Codex on the Flight of Birds (1502). In 1799, George Cayley described the modern airplane as a fixed-wing flying machine with separate parts for lift, propulsion, and control. In 1856, Frenchman Jean-Marie Le Bris made the first powered flight, with his glider pulled by a horse on a beach. The Russian Alexander F. Mozhaisky also made some new designs. In 1883, the American John J. Montgomery made a controlled glider flight, and Otto Lilienthal, Percy Pilcher, and Octave Chanute made similar flights. Lilienthal's work strongly inspired the Wright brothers, and his "Lilienthal Normalsegelapparat" is considered the first airplane in series production. Lawrence Hargrave developed a box kite that could lift the weight of a man. The Frenchman Clement Ader built his first flying machine in 1886, the Éole, which had a steam engine of 20 horsepower (15 kW) and a propeller. On 9 October 1890, he tried to fly it, and historians credit this as a powered hop of about 50 m (160 ft).

The American Wright brothers's flights in 1903 are recognized by the Fédération Aéronautique Internationale (FAI), the group that sets standards and keeps records for aeronautics, as "the first sustained and controlled heavier-than-air powered flight." By 1905, the Wright Flyer III could fly in a controlled and stable way for long periods. In 1906, the Brazilian Alberto Santos-Dumont made what was claimed to be the first airplane flight without a catapult, and his flight set a record recognized by the Aéro-Club de France. The Blériot VIII design of 1908 brought together the modern monoplane tractor configuration and was an important step toward the Blériot XI, which crossed the Channel in 1909. World War I showed that airplanes could be used as observation platforms and as machines of war. In 1915, German Luftstreitkräfte Leutnant Kurt Wintgens flew the earliest known fighter aircraft with a synchronized machine gun. Fighter aces appeared, and the greatest by number of aerial victories was Manfred von Richthofen, also known as the Red Baron. In 1919, Alcock and Brown crossed the Atlantic non-stop for the first time. Airplanes played a part in all the major battles of World War II, including the German Blitzkrieg, the Battle of Britain, and the aircraft carrier campaigns of the Pacific War. The first practical jet aircraft, the German Heinkel He 178, was tested in 1939, and the Messerschmitt Me 262 entered service in the German Luftwaffe in 1943. The first jet airliner, the de Havilland Comet, arrived in 1952, followed by the Boeing 707 and the Boeing 747, which was the world's biggest passenger aircraft until the Airbus A380 in 2005. Supersonic airliner flights, including those of the Concorde, have been limited to flying over water because of their sonic boom. A deadly crash in 2000 and high operating costs led the Concorde's operators to remove it from service.

Propulsion

See also: Powered aircraft and Aircraft engine

Main articles: Propeller (aeronautics) and Aircraft engine

A propeller, or airscrew, turns the spinning power from an engine into a swirling flow of air that pushes the aircraft forward or backward. It has a central hub with two or more blades that spin around together. Propellers can be powered by reciprocating engines (piston engines), gas turbines, or electric motors. The thrust a propeller makes depends partly on the area its blades sweep through. Blades that move faster than the speed of sound lose efficiency. Propeller-driven aircraft are designed to fly up to Mach 0.6, and faster aircraft use jet engines. Piston engines in aircraft come in three main types: radial, in-line, and flat or horizontally opposed. Gas turbine engines that drive propellers are called turboprops. Electric aircraft run on electric motors powered by fuel cells, solar cells, ultracapacitors, power beaming, or batteries. Most electric aircraft are still experimental, though some unmanned aerial vehicles and a few production models are on the market.

Main article: Jet engine

Jet aircraft are powered by jet engines, which are more powerful than piston engines of the same size or weight, quieter, and work well at high altitude. Most jet aircraft use turbofan engines, which push air both through and around the engine's turbine. The ratio of these two airflows is called the by-pass ratio. Airliners use high by-pass engines for fuel efficiency, while supersonic aircraft such as jet fighters use low-bypass turbofans. Combat aircraft may use an afterburner to add power for short periods, and many jets use thrust reversers to slow down after landing. A ramjet has no major moving parts and needs forward motion before it can make thrust, as the Lockheed D-21, a Mach 3+ reconnaissance drone, did when it was launched from a parent aircraft. A scramjet is a specialized ramjet that works only at supersonic speeds, and the NASA X-43 set a jet-powered speed record in 2004 at Mach 9.7. Rocket motors make thrust by burning fuel with an oxidizer and pushing out gas through a nozzle. Rocket aircraft carry their own oxidizer, while jets take it from the air. In World War II, the Germans used the Me 163 Komet rocket-powered aircraft. The Bell X-1 became the first plane to break the sound barrier in level flight in 1948. The North American X-15 set many speed and altitude records in the 1960s, and some rocket planes are designed as spaceplanes, such as SpaceShipTwo, for travel beyond the Earth's atmosphere.

Design and manufacture

Main article: Aerospace manufacturer

Companies build most airplanes to make many of them for customers. Designing and planning a plane, including safety tests, can take up to four years for small turboprops and longer for larger planes. Engineers use drawings, equations, computer simulations, wind tunnel tests, and past experience to predict how the plane will behave. When the design is ready, the company builds a few prototypes for ground testing, and a representative from an aviation agency often makes the first flight. Flight tests continue until the plane meets all the requirements, and then the country's aviation agency allows production to begin. In the United States, this agency is the Federal Aviation Administration (FAA). In the European Union, it is the European Aviation Safety Agency (EASA). In the United Kingdom, it is the Civil Aviation Authority (CAA). In Canada, it is the Civil Aviation Authority of Transport Canada. Welded parts for aerospace and defense must meet very strict safety rules, and Nadcap sets global quality standards for aerospace engineering.

When planes are sold to other countries, the country where the plane will fly must also approve it. For example, Airbus planes need FAA certification to fly in the United States, and Boeing planes need EASA approval to fly in the European Union. Rules have also reduced engine noise, in response to noise pollution from growing air traffic over cities near airports. Some people build small planes at home as homebuilt aircraft, sometimes from kits of parts. Few companies make planes on a large scale. Instead, dozens or even hundreds of companies make the parts, which are sent to the main plant for assembly. Finished planes are carefully inspected and go through flight tests to check that all systems work and that the plane handles well. The plane may then be customized for a customer's needs.

Characteristics

The main frame of an airplane is called the airframe. Early planes were mostly made of wood with fabric on the wings. As engines and speeds improved, more parts became metal, and composite materials are used more today. The large wings have a curved airfoil shape, like a bird's wing. As the plane moves forward, the wings push air downward, which creates lifting force to hold the plane up. The wings also help keep the plane steady from roll. Wings come in different designs. A monoplane has one wing level, a biplane has two stacked wings, and a triplane has three. Shapes like the delta wing and swept wing help with speed, and a variable-sweep wing can change shape during flight.

The fuselage is the long, thin body of the plane. It is usually shaped with tapered or rounded ends to make it aerodynamically smooth. It holds the flight crew, passengers, cargo or payload, fuel and engines, and pilots fly from a cockpit. At the tail, a vertical stabilizer helps control yaw and holds the rudder, while a horizontal stabilizer or tailplane helps control pitch and holds the elevators. The landing gear supports the plane on the ground, or floats support it on water. Some designs are unusual. A flying wing has no clear fuselage, a blended wing body joins the wings smoothly into the body, and a lifting body makes lift with its body. Some planes also have a canard foreplane ahead of the main wing. Airplanes use flight control systems and cockpit instruments to help pilots fly safely.

Further information: Fixed-wing aircraft § Aircraft controls, and Fixed-wing aircraft § Cockpit instrumentation

Safety

Main article: Aviation safety

When risk is measured by deaths per passenger kilometer, air travel is about 10 times safer than travel by bus or rail. However, when risk is measured by deaths per journey, air travel is significantly more dangerous than car, rail, or bus travel. For this reason, air travel insurance is relatively expensive, because insurers generally use the deaths per journey statistic.

There is also a big difference between airliners and smaller private planes. Using the per-mile statistic, airliners are 8.3 times safer than smaller planes.

Environmental impact

Main article: Environmental impact of aviation

Like all activities involving combustion, fossil-fuel-powered aircraft release soot and other pollutants into the air. Greenhouse gases such as carbon dioxide (CO₂) are also produced. Airplanes that fly high, near the tropopause, mainly large jet airliners, release particles and leave contrails. Both can increase cirrus cloud formation, and cloud cover may have increased by up to 0.2% since the birth of aviation. These high-flying airplanes can also release nitrogen compounds, which react with ozone and increase ozone concentrations.

Most light piston aircraft burn avgas, which contains tetraethyllead (TEL). Some lower-compression piston engines can run on unleaded mogas. Turbine and diesel engines, which do not need lead, are used on some newer light aircraft. Some non-polluting light electric aircraft are already in production. Another impact of airplanes is noise pollution, mainly from aircraft taking off and landing.