Aircraft controls

An aircraft ( aircraft) is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or the dynamic lift of an airfoil, or, in a few cases, direct downward thrust from its engines. Common examples of aircraft include airplanes, rotorcraft (including helicopters), airships (including blimps), gliders, paramotors, and hot air balloons. Part 1 (Definitions and Abbreviations) of Subchapter A of Chapter I of Title 14 of the U. S. Code of Federal Regulations states that aircraft "means a device that is used or intended to be used for flight in the air."

The human activity that surrounds aircraft is called ''aviation''. The science of aviation, including designing and building aircraft, is called ''aeronautics.'' Crewed aircraft are flown by an onboard pilot, whereas unmanned aerial vehicles may be remotely controlled or self-controlled by onboard computers. Aircraft may be classified by different criteria, such as lift type, aircraft propulsion (if any), usage and others.

History

The history of aviation spans over two millennia, from the earliest innovations like kites and attempts at tower jumping to supersonic and hypersonic flight in powered, heavier-than-air jet aircraft. Kite flying in China, dating back several hundred years BC, is considered the earliest example of man-made flight. In the 15th century, Leonardo da Vinci created flying machine designs incorporating aeronautical concepts, but they were unworkable due to the limitations of contemporary knowledge.

In the late 18th century, the Montgolfier brothers invented the hot-air balloon which soon led to manned flights. At almost the same time, the discovery of hydrogen gas led to the invention of the hydrogen balloon. Various theories in mechanics by physicists during the same period, such as fluid dynamics and Newton's laws of motion, led to the development of modern aerodynamics; most notably by Sir George Cayley. Balloons, both free-flying and tethered, began to be used for military purposes from the end of the 18th century, with France establishing balloon companies during the French Revolution.Hallion (2003)

In the 19th century, especially the second half, experiments with gliders provided the basis for learning the dynamics of winged aircraft; most notably by Cayley, Otto Lilienthal, and Octave Chanute. By the early 20th century, advances in engine technology and aerodynamics made controlled, powered, manned heavier-than-air flight possible for the first time. In 1903, following their pioneering research and experiments with wing design and aircraft control, the Wright brothers successfully incorporated all of the required elements to create and fly the first airplane. In 1906 Charles Frederick Page was granted the first U.S. patent for an aircraft. The basic configuration with its characteristic cruciform tail was established by 1909, followed by rapid design and performance improvements aided by the development of more powerful engines.

The first vessels of the air were the rigid steerable balloons pioneered by Ferdinand von Zeppelin that became synonymous with airships and dominated long-distance flight until the 1930s, when large flying boats became popular for trans-oceanic routes. After World War II, the flying boats were in turn replaced by airplanes operating from land, made far more capable first by improved propeller engines, then by jet engines, which revolutionized both civilian air travel and military aviation.

In the latter half of the 20th century, the development of digital electronics led to major advances in flight instrumentation and "fly-by-wire" systems. The 21st century has seen the widespread use of pilotless drones for military, commercial, and recreational purposes. With computerized controls, inherently unstable aircraft designs, such as flying wings, have also become practical.

Methods of lift

Lighter-than-air

Lighter-than-air aircraft or '' aerostats'' use buoyancy to float in the air in much the same way that ships float on the water. They are characterized by one or more large cells or canopies, filled with a lifting gas such as helium, hydrogen or hot air, which is less dense than the surrounding air. Other gases lighter than air also theoretically work, however, such gases also needs to be same for human use (non-flammable, non-toxic).

Small hot-air balloons, called sky lanterns, were first invented in ancient China prior to the 3rd century BC and used primarily in cultural celebrations, although they also had military purposes. They, along with kites, were two forms of unmanned aircraft that originated from China. Kites were also used in the military, but unlike sky lanterns, their flight is caused by the differences of air pressure beneath and above the kite.
A balloon was originally any aerostat, while the term airship was used for large, powered aircraft designs — usually fixed-wing. In 1919, Frederick Handley Page was reported as referring to "ships of the air," with smaller passenger types as "Air yachts." In the 1930s, large intercontinental flying boats were also sometimes referred to as "ships of the air" or "flying-ships".

Lighter-than-air aircraft don't typically require a pilot's license in the United States. In most countries in Europe, standards for flying Lighter-than-air aircraft tend to be stricter compared to the United States.

Heavier-than-air

Heavier-than-air aircraft or ''aerodynes'' are denser than air and thus must find some way to obtain enough lift that can overcome the aircraft's weight. There are two ways to produce dynamic upthrust — aerodynamic lift by having air flowing past an aerofoil (such dynamic interaction of aerofoils with air is the origin of the term "aerodyne"), or powered lift in the form of reactional lift from downward engine thrust.

Aerodynamic lift involving wings is the most common, and can be achieved via two methods. Fixed-wing aircraft (airplanes and gliders) achieve airflow past the wings by having the entire aircraft moving forward through the air, while rotorcraft (helicopters and autogyros) do so by having mobile, elongated wings spinning rapidly around a mast in an assembly known as the rotor.

Fixed-wing Aircraft

Gliders were one of the first forms of a fixed wing aircraft. They are a special type of aircraft that doesn't require an engine. The first person to successfully build a human-carrying glider was George Cayley, who also was the first to discover the four major aerodynamic forces. The first powered aircraft (Airplane) was invented by Wilbur and Orville Wright.

Rotorcraft

A ''rotary-wing aircraft'', ''rotorwing aircraft'' or ''rotorcraft'' is a heavier-than-air aircraft with rotary wings that spin around a vertical mast to generate lift. The assembly of several rotor blades mounted on a single mast is referred to as a rotor. The International Civil Aviation Organization (ICAO) defines a rotorcraft as "supported in flight by the reactions of the air on one or more rotors".

Rotorcraft generally include aircraft where one or more rotors provide lift throughout the entire flight, such as helicopters, gyroplanes, autogyros, and gyrodynes Compound rotorcraft augment the rotor with additional thrust engines, propellers, or static lifting surfaces. Some types, such as helicopters, are capable of vertical takeoff and landing. An aircraft which uses rotor lift for vertical flight but changes to solely fixed-wing lift in horizontal flight is not a rotorcraft but a convertiplane.

Other methods of lift

* A lifting body is an aircraft which produces lift through the shape of its body, rather than its wings or rotors, like conventional aircraft. Lifting bodies were first experimented by NASA in the 1960s-70s, but the idea was already conceived in the 1950s.
* A powered lift aircraft is one which has the capability of vertical takeoff and landing. These aircraft must transition from vertical to lateral movement, which is considered the most dangerous phases of a flight. Classes of powered lift types include VTOL jet aircraft (such as the Harrier jump jet) and tiltrotors, such as the Bell Boeing V-22 Osprey, among others.
* An ornithopter is an aircraft that produces lift through the movement of its wings, akin to how a bird flies.

Size and speed extremes

Size

The largest aircraft by dimensions and volume (as of 2016) is the long British Airlander 10, a hybrid blimp, with helicopter and fixed-wing features, and reportedly capable of speeds up to , and an airborne endurance of two weeks with a payload of up to ."World's largest aircraft the Airlander makes maiden flight in UK,"
16 August 2016, London 'Daily Telegraph' via Telegraph.co.uk. Retrieved 22 November 2016."Airlander 10, the world's largest aircraft, takes off for the first time," 19 August 2016, CBS News (TV) retrieved 22 November 2016.Kottasova, Ivan
"The world's largest aircraft crashes after 2nd test flight"
, 24 August 2016, ''CNN Tech'' on CNN, the Cable News Network. Retrieved 22 November 2016.

The largest aircraft by weight and largest regular fixed-wing aircraft ever built, , was the Antonov An-225 ''Mriya''. That Soviet-built (Ukrainian SSR) six-engine transport of the 1980s was long, with an wingspan. It holds the world payload record, after transporting of goods, and has flown loads commercially. With a maximum loaded weight of , it was also the heaviest aircraft built to date. It could cruise at ."Watch the world's biggest plane land in Australia,"
16 May 2016, Fox News. Retrieved 22 November 2016.Lewis, Danny
"The World's Largest Aircraft Might Lose its Title to a Blimp,"
18 September 2015, ''Smart News'', Smithsonian.com, Smithsonian Institution, Washington, D.C.. Retrieved 22 November 2016."Ask Us – Largest Plane in the World,"
Aerospaceweb.org. Retrieved 22 November 2016. The aircraft was destroyed during the Russo-Ukrainian War.

The largest military airplanes are the Ukrainian Antonov An-124 ''Ruslan'' (world's second-largest airplane, also used as a civilian transport),"World's Second Largest Aircraft,"
28 July 2013, NASA. Retrieved 22 November 2016. and American Lockheed C-5 Galaxy transport, weighing, loaded, over .Loftin, Laurence K., Jr.
"Wide-Body Transports"
, in Chapter 13, "Jet Transports," in Part II, "The Jet Age," in ''Quest for Performance: The Evolution of Modern Aircraft'', NASA SP-468, 1985, Scientific and Technical Information Branch, NASA, Washington, D.C., Updated: 6 August 2004. Retrieved 22 November 2016. The 8-engine, piston/propeller Hughes H-4 ''Hercules'' "Spruce Goose" — an American World War II wooden flying boat transport with a greater wingspan (94m/260 ft) than any current aircraft and a tail height equal to the tallest (Airbus A380-800 at 24.1m/78 ft) — flew only one short hop in the late 1940s and never flew out of ground effect.

The largest civilian airplanes, apart from the above-noted An-225 and An-124, are the Airbus Beluga cargo transport derivative of the Airbus A300 jet airliner, the Boeing Dreamlifter cargo transport derivative of the Boeing 747 jet airliner/transport (the 747-200B was, at its creation in the 1960s, the heaviest aircraft ever built, with a maximum weight of over ), and the double-decker Airbus A380 "super-jumbo" jet airliner (the world's largest passenger airliner)."Airbus reviews A380 schedule,"
29 April 2008, ''The New York Times''. Retrieved 22 November 2016.

Speeds

The fastest fixed-wing aircraft and fastest glider, is the Space Shuttle, which re-entered the atmosphere at nearly Mach 25 or

The fastest recorded powered aircraft flight and fastest recorded aircraft flight of an air-breathing powered aircraft was of the NASA X-43A ''Pegasus'', a scramjet-powered, hypersonic, lifting body experimental research aircraft, at Mach 9.68 or on 16 November 2004.

Prior to the X-43A, the fastest recorded powered airplane flight, and still the record for the fastest manned powered airplane, was the North American X-15, rocket-powered airplane at Mach 6.7 or 7,274 km/h (4,520 mph) on 3 October 1967.

The fastest manned, air-breathing powered airplane is the Lockheed SR-71 Blackbird, a U.S. reconnaissance jet fixed-wing aircraft, having reached on 28 July 1976.

Propulsion and steering

Unpowered aircraft

The main feature of unpowered aircraft is the inability to directly provide thrust through its engines. This means that all unpowered aircraft rely on the environment for sustained flight. Gliders, for example, take advantage of their aerodynamic properties to enable them to travel long distances. Techniques such as thermal circling, where gliders fly into warm air which allows them to rise, prolongs flight time.

Due to the lack of an engine, initial propulsion assistance is usually necessary to ensure flight. A common glider launching method is aerotowing, where another aircraft tows the glider to an altitude from which sustained flight is possible. Steering for a glider is also rudimentary, while more complex gliders like sailplanes usually have joysticks for steering, more basic aircraft like hang gliders rely on the pilot's physical coordination to change the centre of gravity.

Powered aircraft

A powered aircraft is an aircraft with a source of mechanical power, used to produce thrust. Such sources are generally engines, as is the case with airplanes, but can be human-powered in more extreme cases.

Propeller aircraft

Propeller aircraft, as their name suggests, rely on propellers to produce thrust for the airplane.

Jet aircraft

Compared to engines using propellers, jet engines can provide much higher thrust, higher speeds and, above about , greater efficiency.

Rotorcraft

Design and construction

The key parts of an aircraft are generally divided into three categories:
* The ''structure'' ("airframe"Gove, P.B., editor: ''Webster's Third New International Dictionary of the English Language, Unabridged,'' 1993, Merriam-Webster, Springfield, Mass., USACrane, D., editor: ''Dictionary of Aeronautical Terms,'' Third Edition, ASA (Aviation Supplies & Academics), Newcastle, Washington, USA''2012 Federal Aviation Regulations for Aviation Maintenance Technicians,'' 2012, Federal Aviation Administration, U.S. Department of Transportation Gunston, Bill, editor: ''Jane's Aerospace Dictionary'' 1980, Jane's, London / New York / Sydney) comprises the main load-bearing elements and associated equipment, as well as flight controls.
* The ''propulsion system'' (" powerplant""Glossary"
in ''Pilot's Handbook of Aeronautical Knowledge'' (PHAK), Federal Aviation Administration, Washington, D.C., retrieved 12 September 2022) (if it is powered) comprises the power source and associated equipment, as described above.
* The ''avionics'' comprise the electrical and electronic control, navigation and communication systems.Wragg, David W. editor: ''A Dictionary of Aviation,'' 1974, Frederick Fell, New York

Structure

Aerostats

An ''aerostat'' or ''lighter-than-air aircraft'' relies on buoyancy to maintain flight. Aerostats include unpowered balloons (free-flying or tethered) and powered airships. The relative density of an aerostat as a whole is lower than that of the surrounding atmospheric air (hence the name "lighter-than-air"). Its main component is one or more gas capsules made of lightweight skins, containing a lifting gas (hot air, or any gas with lower density than air, typically hydrogen or helium) that displaces a large volume of air to generate enough buoyancy to overcome its own weight. Payload (passengers and cargo) can then be carried on attached components such as a basket, a gondola, a cabin or various hardpoints. With airships, which need to be able to fly against wind, the lifting gas capsules are often protected by a more rigid outer envelope or an airframe, with other gasbags such as ballonets to help modulate buoyancy.

Aerostats are so named because they use aerostatic buoyant force that does not require any forward movement through the surrounding air mass, resulting in the inherent ability to levitate and perform vertical takeoff and landing. This contrasts with the heavier-than-air aerodynes that primarily use aerodynamic lift, which must have consistent airflow over an aerofoil (wing) surface to stay airborne. The term has also been used in a narrower sense, to refer to the statically tethered balloon in contrast to the free-flying airship. This article uses the term in its broader sense.

Aerodynes

Power

The source of motive power for an aircraft is normally called the '' powerplant,'' and includes engine or motor, propeller or rotor, (if any), jet nozzles and thrust reversers (if any), and accessories essential to the functioning of the engine or motor (e.g.: starter, ignition system, intake system, exhaust system, fuel system, lubrication system, engine cooling system, and engine controls).

Powered aircraft are typically powered by internal combustion engines (piston"Internal Combustion Engine,"
Glenn Research Center, National Aeronautics and Space Administration (NASA), retrieved 12 September 2022 or turbine"Engines,"
Glenn Research Center, National Aeronautics and Space Administration (NASA), retrieved 12 September 2022) burning fossil fuels—typically gasoline (avgas) or jet fuel. A very few are powered by rocket power, ramjet propulsion, or by electric motors, or by internal combustion engines of other types, or using other fuels. A very few have been powered, for short flights, by human muscle energy (e.g.: Gossamer Condor).Bryan, C.D.B.: ''The National Air and Space Museum,'' 1979 / 1984, Abrams, New YorkTaylor, Michael J.H., editor: ''Jane's Encyclopedia of Aviation,'' 1989 ed., Portland House / Random House, New York"Electrified Aircraft Propulsion" (EAP)
Glenn Research Center, National Aeronautics and Space Administration (NASA), retrieved 12 September 2022

Avionics

The avionics comprise any ''electronic'' aircraft flight control systems and related equipment, including electronic cockpit instrumentation, navigation, radar, monitoring, and communications systems.

Flight characteristics

Flight envelope

The flight envelope of an aircraft refers to its approved design capabilities in terms of airspeed, load factor and altitude.

Range

The maximal total ''range'' is the maximum distance an aircraft can fly between takeoff and landing. Powered aircraft range is limited by the aviation fuel energy storage capacity (chemical or electrical) considering both weight and volume limits. Unpowered aircraft range depends on factors such as cross-country speed and environmental conditions. The range can be seen as the cross-country ground speed multiplied by the maximum time in the air. The fuel time limit for powered aircraft is fixed by the available fuel (considering reserve fuel requirements) and rate of consumption. The Airbus A350-900ULR is among the longest range airliners.

Some aircraft can gain energy while airborne through the environment (e.g. collecting solar energy or through rising air currents from mechanical or thermal lifting) or from in-flight refueling. These aircraft could theoretically have an infinite range.

''Ferry range'' means the maximum range that an aircraft engaged in ferry flying can achieve. This usually means maximum fuel load, optionally with extra fuel tanks and minimum equipment. It refers to the transport of aircraft without any passengers or cargo. '' Combat radius'' is a related measure based on the maximum distance a warplane can travel from its base of operations, accomplish some objective, and return to its original airfield with minimal reserves.

Flight dynamics

''Flight dynamics'' is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of gravity (cg), known as ''pitch'', ''roll'' and ''yaw''. These are collectively known as ''aircraft attitude'', often principally relative to the atmospheric frame in normal flight, but also relative to terrain during takeoff or landing, or when operating at low elevation. The concept of attitude is not specific to fixed-wing aircraft, but also extends to rotary aircraft such as helicopters, and dirigibles, where the flight dynamics involved in establishing and controlling attitude are entirely different.

Control systems adjust the orientation of a vehicle about its cg. A control system includes control surfaces which, when deflected, generate a moment (or couple from ailerons) about the cg which rotates the aircraft in pitch, roll, and yaw. For example, a pitching moment comes from a force applied at a distance forward or aft of the cg, causing the aircraft to pitch up or down.

A fixed-wing aircraft increases or decreases the lift generated by the wings when it pitches nose up or down by increasing or decreasing the angle of attack (AOA). The roll angle is also known as bank angle on a fixed-wing aircraft, which usually "banks" to change the horizontal direction of flight. An aircraft is streamlined from nose to tail to reduce drag making it advantageous to keep the sideslip angle near zero, though an aircraft may be deliberately "sideslipped" to increase drag and descent rate during landing, to keep aircraft heading same as runway heading during cross-wind landings and during flight with asymmetric power.

Stability

A fixed wing is typically unstable in pitch, roll, and yaw. Pitch and yaw stabilities of conventional fixed wing designs require horizontal and vertical stabilisers,Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', p. 194. Aviation Supplies & Academics, 1997. Aviation Publishers Co. Limited, ''From the Ground Up'', p. 10 (27th revised edition) which act similarly to the feathers on an arrow. These stabilizing surfaces allow equilibrium of aerodynamic forces and to stabilise the flight dynamics of pitch and yaw.

Control

Environmental impact

Aircraft engines produce gases, noise, and particulates from fossil fuel combustion, raising environmental concerns over their global effects and on local air quality.

Jet airliners contribute to climate change by emitting carbon dioxide (), the best understood greenhouse gas, and, with less scientific understanding, nitrogen oxides, contrails and particulates. Their radiative forcing is estimated at 1.4 that of alone, excluding induced cirrus cloud with a very low level of scientific understanding.
In 2018, global commercial operations generated 2.4% of emissions. Jet airliners have become more fuel efficient and emissions per revenue ton-kilometer (RTK) in 2018 were 47% of those in 1990. In 2018, emissions averaged 88 grams of per revenue passenger per km. While the aviation industry is more fuel efficient, overall emissions have risen as the volume of air travel has increased. By 2020, aviation emissions were 70% higher than in 2005 and they could grow by 300% by 2050.

Aircraft noise pollution disrupts sleep, children's education and could increase cardiovascular risk. Airports can generate water pollution due to their extensive handling of jet fuel and deicing chemicals if not contained, contaminating nearby water bodies. Aviation activities emit ozone and ultrafine particles, both of which are health hazards. Piston engines used in general aviation burn Avgas, releasing toxic lead.

Aviation's environmental footprint can be reduced by better fuel economy in aircraft, or air traffic control and flight routes can be optimized to lower non- effects on climate from , particulates or contrails.
Aviation biofuel, emissions trading and carbon offsetting, part of the ICAO's CORSIA, can lower emissions. Aviation usage can be lowered by short-haul flight bans, train connections, personal choices and aviation taxation and subsidies. Fuel-powered aircraft may be replaced by hybrid electric aircraft and electric aircraft or by hydrogen-powered aircraft.
Since 2021, the IATA members plan net-zero carbon emissions by 2050, followed by the ICAO in 2022.

Uses for aircraft

Military

A military aircraft is any aircraft that is operated by a legal or insurrectionary armed service of any type. Military aircraft can be either combat or non-combat:

* Combat aircraft are aircraft designed to destroy enemy equipment using its own armament. Combat aircraft are typically developed and procured only by military forces.
* Non-combat aircraft, such as transports and tankers, are not designed for combat as their primary function but may carry weapons for self-defense. These mainly operate in support roles, and may be developed by either military forces or civilian organizations.

Civil

''Civil aviation'' is one of two major categories of flying, representing all non-military and non-state aviation, which can be both private and commercial. Most countries in the world are members of the International Civil Aviation Organization and work together to establish common Standards and Recommended Practices for civil aviation through that agency.

Civil aviation includes three major categories:

* Commercial air transport, including scheduled and non-scheduled passenger and cargo flights
* Aerial work, in which an aircraft is used for specialized services such as agriculture, photography, surveying, search and rescue, etc.
* General aviation (GA), including all other civil flights, private or commercial

Although scheduled air transport is the larger operation in terms of passenger numbers, GA is larger in the number of flights (and flight hours, in the U.S.) In the U.S., GA carries 166 million passengers each year, more than any individual airline, though less than all the airlines combined. Since 2004, the U.S. airlines combined have carried over 600 million passengers each year, and in 2014, they carried a combined 662,819,232 passengers.

Some countries also make a regulatory distinction based on whether aircraft are flown for hire, like:

* Commercial aviation includes most or all flying done for hire, particularly scheduled service on airlines; and
* Private aviation includes pilots flying for their own purposes (recreation, business meetings, etc.) without receiving any kind of remuneration.

All scheduled air transport is commercial, but general aviation can be either commercial or private. Normally, the pilot, aircraft, and operator must all be authorized to perform commercial operations through separate commercial licensing, registration, and operation certificates.

Experimental

An ''experimental aircraft'' is an aircraft intended for testing new aerospace technologies and design concepts.

The term ''research aircraft'' or '' testbed aircraft'', by contrast, generally denotes aircraft modified to perform scientific studies, such as weather research or geophysical surveying, similar to a research vessel.

The term "experimental aircraft" also has specific legal meaning in Australia, the United States and some other countries; usually used to refer to aircraft flown with an experimental certificate. In the United States, this also includes most homebuilt aircraft, many of which are based on conventional designs and hence are experimental only in name because of certain restrictions in operation.14CFR 21.191
, US Federal Aviation Administration. Retrieved 2018-01-12

Model

See also

Lists

* Early flying machines
* Flight altitude record
* List of aircraft
* List of civil aircraft
* List of fighter aircraft
* List of individual aircraft
* List of large aircraft
* List of aviation, aerospace and aeronautical terms

Topics

* Aircraft hijacking
* Aircraft spotting
* Air traffic control
* Airport
* Flying car
* Personal air vehicle
* Powered parachute
* Spacecraft
* Spaceplane

References

*

External links

History

The Evolution of Modern Aircraft (NASA)




Smithsonian Air and Space Museum
– online collection with a particular focus on history of aircraft and spacecraft

Amazing Early Flying Machines
slideshow by ''Life'' magazine

Information

Airliners.net

Aviation Dictionary
– free aviation terms, phrases and jargons

''New Scientist''s aviation page

{{Authority control