Aircraft

"Flying machine" redirects here. For other uses, see Flying machine (disambiguation). This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (January 2009) An Airbus A380, the world's largest passenger airliner Part of a series on Categories of aircraft Supported by lighter-than-air gases (aerostats) Unpowered Powered Balloon Airship Supported by LTA gases + aerodynamic lift Unpowered Powered Hybrid moored balloon Hybrid airship Supported by aerodynamic lift (aerodynes) Unpowered Powered Unpowered fixed-wing Powered fixed-wing Glider hang gliders Paraglider Kite Powered airplane (aeroplane) powered hang gliders Powered paraglider Flettner airplane Ground-effect vehicle Powered hybrid fixed/rotary wing Tiltwing Tiltrotor Coleopter Unpowered rotary-wing Powered rotary-wing Rotor kite Autogyro Gyrodyne ("Heliplane") Helicopter Powered aircraft driven by flapping Ornithopter Other means of lift Unpowered Powered Hovercraft Flying Bedstead Avrocar A hot air balloon (aircraft) in flight. Aircraft are vehicles which are able to fly by being supported by the air, or in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.1 Although rockets and missiles also travel through the atmosphere, most are not considered aircraft because they use rocket thrust instead of aerodynamics as the primary means of lift. However, rocket planes and cruise missiles are considered aircraft because they rely on lift from the air. Another type of aircraft is the spaceplane which is an aircraft designed to fly up to extreme altitudes into space and land as a conventional aircraft. The human activity which surrounds aircraft is called aviation. Manned aircraft are flown by an onboard pilot. Unmanned aerial vehicles may be remotely controlled or self-controlled by onboard computers. Target drones are an example of UAVs. Aircraft may be classified by different criteria, such as lift type, propulsion, usage and others. Contents 1 History 2 Methods of lift 2.1 Lighter than air – aerostats 2.2 Heavier than air – aerodynes 2.2.1 Fixed-wing 2.2.2 Rotorcraft 2.2.3 Other methods of lift 3 Propulsion 3.1 Unpowered 3.1.1 Gliders 3.1.2 Balloons 3.1.3 Kites 3.2 Powered 3.2.1 Propeller 3.2.2 Jet 3.2.3 Helicopters 3.2.4 Other methods of propulsion 4 General construction 4.1 Airframe 4.2 Undercarriage 4.3 Fuselage 4.4 Wing configuration 4.5 Aircraft engine 4.6 Flight control surfaces 4.7 Empennage 4.8 Flight deck 4.9 Cabin 5 Performance of aircraft 5.1 Flight envelope 5.2 Aircraft range 6 Aircraft flight dynamics 7 Areas of use 7.1 Military 7.2 Civil 7.2.1 Commercial 7.2.2 General aviation 7.3 Experimental 7.4 Model 8 Aircraft manufacture 8.1 Manufacturers and types 8.2 Aircraft design 9 See also 9.1 Lists 9.2 Topics 10 References 11 External links // History Main article: Aviation history See also: Timeline of aviation The history of aircraft development divides broadly into five eras: Pioneers of flight First World War Inter-war, sometimes called the Golden Age Second World War Postwar era, also called the jet age Methods of lift Lighter than air – aerostats 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 gasbags or canopies, filled with a relatively low density gas such as helium, hydrogen or hot air, which is less dense than the surrounding air. When the weight of this is added to the weight of the aircraft structure, it adds up to the same weight as the air that the craft displaces. Small hot air balloons called sky lanterns date back to the 3rd century BC, and were only the second type of aircraft to fly, the first being kites. Originally, a balloon was any aerostat, while the term airship was used for large, powered aircraft designs – usually fixed-wingcitation needed – though none had yet been built. The advent of powered balloons, called dirigible balloons, and later of rigid hulls allowing a great increase in size, began to change the way these words were used. Huge powered aerostats, characterized by a rigid outer framework and separate aerodynamic skin surrounding the gas bags, were produced, the Zeppelins being the largest and most famous. There were still no fixed-wing aircraft or non-rigid balloons large enough to be called airships, so "airship" came to be synonymous with these aircraft. Then several accidents, such as the Hindenburg disaster in 1937, led to the demise of these airships. Nowadays a "balloon" is an unpowered aerostat, whilst an "airship" is a powered one. A powered, steerable aerostat is called a dirigible. Sometimes this term is applied only to non-rigid balloons, and sometimes dirigible balloon is regarded as the definition of an airship (which may then be rigid or non-rigid). Non-rigid dirigibles are characterized by a moderately aerodynamic gasbag with stabilizing fins at the back. These soon became known as blimps. During the Second World War, this shape was widely adopted for tethered balloons; in windy weather, this both reduces the strain on the tether and stabilizes the balloon. The nickname blimp was adopted along with the shape. In modern times any small dirigible or airship is called a blimp, though a blimp may be unpowered as well as powered. Heavier than air – aerodynes Heavier-than-air aircraft must find some way to push air or gas downwards, so that a reaction occurs (by Newton's laws of motion) to push the aircraft upwards. This dynamic movement through the air is the origin of the term aerodyne. There are two ways to produce dynamic upthrust: aerodynamic lift, and powered lift in the form of engine thrust. Aerodynamic lift is the most common, with fixed-wing aircraft being kept in the air by the forward movement of wings, and rotorcraft by spinning wing-shaped rotors sometimes called rotary wings. A wing is a flat, horizontal surface, usually shaped in cross-section as an aerofoil. To fly, air must flow over the wing and generate lift. A flexible wing is a wing made of fabric or thin sheet material, often stretched over a rigid frame. A kite is tethered to the ground and relies on the speed of the wind over its wings, which may be flexible or rigid, fixed or rotary. With powered lift, the aircraft directs its engine thrust vertically downwards. The initialism VTOL (vertical take off and landing) is applied to aircraft that can take off and land vertically. Most are rotorcraft. Others, such as the Hawker Siddeley Harrier and F-35B, take off and land vertically using powered lift and transfer to aerodynamic lift in steady flight. Similarly, STOL stands for short take off and landing. Some VTOL aircraft often operate in a short take off/vertical landing mode known as STOVL. A pure rocket is not usually regarded as an aerodyne, because it does not depend on the air for its lift (and can even fly into space); however, many aerodynamic lift vehicles have been powered or assisted by rocket motors. Rocket-powered missiles which obtain aerodynamic lift at very high speed due to airflow over their bodies, are a marginal case. Fixed-wing NASA test aircraft A size comparison of some of the largest fixed-wing aircraft. The Airbus A380-800 (largest airliner), the Boeing 747-8, the Antonov An-225 (aircraft with the greatest payload) and the Hughes H-4 "Spruce Goose" (aircraft with greatest wingspan). Airplanes or aeroplanes are technically called fixed-wing aircraft. The forerunner of the fixed-wing aircraft is the kite. Whereas a fixed-wing aircraft relies on its forward speed to create airflow over the wings, a kite is tethered to the ground and relies on the wind blowing over its wings to provide lift. Kites were the first kind of aircraft to fly, and were invented in China around 500 BC. Much aerodynamic research was done with kites before test aircraft, wind tunnels and computer modelling programs became available. The first heavier-than-air craft capable of controlled free flight were gliders. A glider designed by Cayley carried out the first true manned, controlled flight in 1853. Besides the method of propulsion, fixed-wing aircraft are generally characterized by their wing configuration. The most important wing characteristics are: Number of wings – Monoplane, biplane, etc. Wing support – Braced or cantilever, rigid or flexible. Wing planform – including aspect ratio, angle of sweep and any variations along the span (including the important class of delta wings). Location of the horizontal stabilizer, if any. Dihedral angle – positive, zero or negative (anhedral). A variable geometry aircraft can change its wing configuration during flight. A flying wing has no fuselage, though it may have small blisters or pods. The opposite of this is a lifting body which has no wings, though it may have small stabilising and control surfaces. Most fixed-wing aircraft feature a tail unit or empennage incorporating vertical, and often horizontal, stabilising surfaces. Seaplanes are aircraft that land on water, and they fit into two broad classes: Flying boats are supported on the water by their fuselage. A float plane's fuselage remains clear of the water at all times, the aircraft being supported by two or more floats attached to the fuselage and/or wings. Some examples of both flying boats and float planes are amphibious, being able to take off from and alight on both land and water. Some people consider wing-in-ground-effect vehicles to be fixed-wing aircraft, others do not. These craft "fly" close to the surface of the ground or water. An example is the Russian ekranoplan (nicknamed the "Caspian Sea Monster"). Man-powered aircraft also rely on ground effect to remain airborne, but this is only because they are so underpowered—the airframe is theoretically capable of flying much higher. Rotorcraft Mil Mi-26, the world's largest production helicopter.2 Main article: Rotorcraft Rotorcraft, or rotary-wing aircraft, use a spinning rotor with aerofoil section blades (a rotary wing) to provide lift. Types include helicopters, autogyros and various hybrids such as gyrodynes and compound rotorcraft. Helicopters have powered rotors. The rotor is driven (directly or indirectly) by an engine and pushes air downwards to create lift. By tilting the rotor forwards, the downwards flow is tilted backwards, producing thrust for forward flight. US-Recognition Manual (very likely copy of German drawing). Autogyros or gyroplanes have unpowered rotors, with a separate power plant to provide thrust. The rotor is tilted backwards. As the autogyro moves forward, air blows upwards across the rotor, making it spin.(cf. Autorotation) This spinning dramatically increases the speed of airflow over the rotor, to provide lift. Juan de la Cierva (a Spanish civil engineer) used the product name autogiro, and Bensen used gyrocopter. Rotor kites, such as the Focke Achgelis Fa 330 are unpowered autogyros, which must be towed by a tether to give them forward ground speed or else be tether-anchored to a static anchor in a high-wind situation for kited flight. Gyrodynes are a form of helicopter, where forward thrust is obtained from a separate propulsion device rather than from tilting the rotor. The definition of a 'gyrodyne' has changed over the years, sometimes including equivalent autogyro designs. The Heliplane is a similar idea. Compound rotorcraft have wings which provide some or all of the lift in forward flight. Compound helicopters and compound autogyros have been built, and some forms of gyroplane may be referred to as compound gyroplanes. They are nowadays classified as powered lift types and not as rotorcraft. Tiltrotor aircraft (such as the V-22 Osprey) have their rotors horizontal for vertical flight, and pivot the rotors vertically like a propeller for forward flight. The Coleopter had a cylindrical wing forming a duct around the rotor. On the ground it sat on its tail, and took off and landed vertically like a helicopter. The whole aircraft would then have tilted forward to fly as a propeller-driven fixed-wing aircraft using the duct as a wing (though this transition was never achieved in practice.) Some rotorcraft have reaction-powered rotors with gas jets at the tips, but most have one or more lift rotors powered from engine-driven shafts. Other methods of lift X24B lifting body, specialized glider A lifting body is the opposite of a flying wing. In this configuration the aircraft body is shaped to produce lift. If there are any wings, they are too small to provide significant lift and are used only for stability and control. Lifting bodies are not efficient: they suffer from high drag, and must also travel at high speed to generate enough lift to fly. Many of the research prototypes, such as the Martin-Marietta X-24, which led up to the Space Shuttle were lifting bodies (though the shuttle itself is not), and some supersonic missiles obtain lift from the airflow over a tubular body. The flat bodies of recent jet fighters also produce lift, as in the F-14 Tomcat's "pancake". Powered lift types rely on engine-derived lift for vertical takeoff and landing (VTOL). Most types transition to fixed-wing lift for horizontal flight. Classes of powered lift types include VTOL jet aircraft (such as the Harrier jump-jet) and tiltrotors (such as the V-22 Osprey), among others. A few examples rely entirely on engine thrust to provide lift throughout the whole flight. There are few practical applications. Experimental designs have been built for personal fan-lift hover platforms and jetpacks or for VTOL research (for example the flying bedstead). The Flettner airplane has a spinning cylinder in place of a wing, relying on the Magnus effect to create lift. The FanWing is a recent innovation with some similarities to the Flettner rotor design. It uses a fixed wing with a cylindrical fan mounted spanwise just above. As the fan spins, it creates an airflow backwards over the upper surface of the wing, creating lift. The FanWing is (2010) in development in the United Kingdom. Propulsion Main article: air propulsion Unpowered Gliders Main article: Glider aircraft Heavier-than-air unpowered aircraft such as gliders (i.e. sailplanes), hang gliders and paragliders, and other gliders usually do not employ propulsion once airborne. Take-off may be by launching forwards and downwards from a high location, or by pulling into the air on a tow-line, by a ground-based winch or vehicle, or by a powered "tug" aircraft. For a glider to maintain its forward air speed and lift, it must descend in relation to the air (but not necessarily in relation to the ground). Some gliders can 'soar'- gain height from updrafts such as thermal currents. The first practical, controllable example was designed and built by the British scientist and pioneer George Cayley, who many recognise as the first aeronautical engineer.3 Balloons Main article: Balloon (aircraft) Balloons drift with the wind, though normally the pilot can control the altitude, either by heating the air or by releasing ballast, giving some directional control (since the wind direction changes with altitude). A wing-shaped hybrid balloon can glide directionally when rising or falling; but a spherically shaped balloon does not have such directional control. Kites Main article: kite Kites are aircraft4 that are tethered to the ground or other object (fixed or mobile) that maintains tension in the tether or kite line; they rely on virtual or real wind blowing over and under them to generate lift and drag. Kytoons are balloon kites that are shaped and tethered to obtain kiting deflections, and can be lighter-than-air, neutrally buoyant, or heavier-than air. Powered Propeller Main article: Propeller A turboprop-engined DeHavilland Twin Otter adapted as a floatplane A propeller or airscrew comprises a set of small, wing-like aerofoils set around a central hub which spins on an axis aligned in the direction of travel. Spinning the propeller creates aerodynamic lift, or thrust, in a forward direction. A tractor design mounts the propeller in front of the power source, while a pusher design mounts it behind. Although the pusher design allows cleaner airflow over the wing, tractor configuration is more common because it allows cleaner airflow to the propeller and provides a better weight distribution. A contra-prop arrangement has a second propeller close behind the first one on the same axis, which rotates in the opposite direction. A variation on the propeller is to use many broad blades to create a fan. Such fans are traditionally surrounded by a ring-shaped fairing or duct, as ducted fans. Many kinds of power plant have been used to drive propellers. The earliest designs used man power to give dirigible balloons some degree of control, and go back to Jean-Pierre Blanchard in 1784. Attempts to achieve heavier-than-air man-powered flight did not succeed fully until Paul MacCready's Gossamer Condor in 1977. Gossamer Albatross, a human-powered aircraft The first powered flight was made in a steam-powered dirigible by Henri Giffard in 1852. Attempts to marry a practical lightweight steam engine to a practical fixed-wing airframe did not succeed until much later, by which time the internal combustion engine was already dominant. From the first controlled powered fixed-wing aircraft flight by the Wright brothers until World War II, propellers turned by the internal combustion piston engine were virtually the only type of propulsion system in use. The piston engine is still used in the majority of smaller aircraft produced, since it is efficient at the lower altitudes and slower speeds suited to propellers. Turbine engines need not be used as jets (see below), but may be geared to drive a propeller in the form of a turboprop. Modern helicopters also typically use turbine engines to power the rotor. Turbines provide more power for less weight than piston engines, and are better suited to small-to-medium size aircraft or larger, slow-flying types. Some turboprop designs (see below) mount the propeller directly on an engine turbine shaft, and are called propfans. Since the 1940s, propellers and propfans with swept tips or curved "scimitar-shaped" blades have been studied for use in high-speed applications so as to delay the onset of shockwaves, in similar manner to wing sweepback, where the blade tips approach the speed of sound. The Airbus A400M turboprop transport aircraft is expected to provide the first production example: note that it is not a propfan because the propellers are not mounted direct on the engine shaft but are driven through reduction gearing. Other less common power sources include: Electric motors, often linked to solar panels to create a solar-powered aircraft. Rubber bands, wound many times to store energy, are mostly used for flying models. Jet Main article: Jet aircraft Airbreathing jet engines provide thrust by taking in air, burning it with fuel in a combustion chamber, and accelerating the exhaust rearwards so that it ejects at high speed. The reaction against this acceleration provides the engine thrust. A jet-engined Boeing 777 taking off Jet engines can provide much higher thrust than propellers, and are naturally efficient at higher altitudes, being able to operate above 40,000 ft (12,000 m). They are also much more fuel-efficient at normal flight speeds than rockets. Consequently, nearly all high-speed and high-altitude aircraft use jet engines. The early turbojet and modern turbofan use a spinning turbine to create airflow for takeoff and to provide thrust. Many, mostly in military aviation, use afterburners which inject extra fuel into the exhaust. Use of a turbine is not absolutely necessary: other designs include the crude pulse jet, high-speed ramjet and the still-experimental supersonic-combustion ramjet or scramjet. These designs require an existing airflow to work and cannot work when stationary, so they must be launched by a catapult or rocket booster, or dropped from a mother ship. The bypass turbofan engines of the Lockheed SR-71 were a hybrid design – the aircraft took off and landed in jet turbine configuration, and for high-speed flight the afterburner was lit and the turbine bypassed, to create a ramjet. The motorjet was a very early design which used a piston engine in place of the combustion chamber, similar to a turbocharged piston engine except that the thrust is derived from the turbine instead of the crankshaft. It was soon superseded by the turbojet and remained a curiosity. Helicopters HAL Dhruv, a multi-role utility helicopter. Main article: Helicopter The rotor of a helicopter, may, like a propeller, be powered by a variety of methods such as an internal-combustion engine or jet turbine. Tip jets, fed by gases passing along hollow rotor blades from a centrally mounted engine, have been experimented with. Attempts have even been made to mount engines directly on the rotor tips. Helicopters obtain forward propulsion by angling the rotor disc so that a proportion of its lift is directed forwards to provide thrust. Other methods of propulsion Rocket-powered aircraft have occasionally been experimented with, and the Messerschmitt Komet fighter even saw action in the Second World War. Since then they have been restricted to rather specialised niches, such as the Bell X-1 which broke the sound barrier or the North American X-15 which traveled up into space where no oxygen is available for combustion (rockets carry their own oxidant). Rockets have more often been used as a supplement to the main powerplant, typically to assist takeoff of heavily loaded aircraft, but also in a few experimental designs such as the Saunders-Roe SR.53 to provide a high-speed dash capability. The flapping-wing ornithopter is a category of its own. These designs may have potential, but no practical device has been created beyond research prototypes, simple toys, and a model hawk used to freeze prey into stillness so that it can be captured. General construction Airframe Main article: airframe Airframe diagram for a AgustaWestland AW101 helicopter The airframe of an aircraft is its mechanical structure,5 which is typically considered to exclude the propulsion system. Airframe design is a field of engineering that combines aerodynamics, materials technology and manufacturing methods to achieve balances of performance, reliability and cost. Undercarriage Main article: Undercarriage The undercarriage or landing gear in aviation, is the structure that supports an aircraft on the ground and allows it to taxi, takeoff and land. Typically wheels are used, but skids, floats or a combination of these and other elements can be deployed, depending on the surface. Fuselage Main article: fuselage Fuselage of a Boeing 737 shown in brown The fuselage (from the French fuselé "spindle-shaped") is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull. The fuselage also serves to position control and stabilization surfaces in specific relationships to lifting surfaces, required for aircraft stability and maneuverability. Wing configuration Main article: Wing configuration Many different styles and arrangements of wings have and are used on heavier-than-air aircraft, and some lighter than air aircraft also have wings. The common wing configuration types have included monoplanes which have one wing each side, biplane which have 4 wings. Wings also vary greatly in planform which is their shape viewed from above. Wings can be swept backwards or be delta wings and can have many other shapes. Aircraft engine Main article: aircraft engine An aircraft engine is a power source for an aircraft. Aircraft engines are almost always either lightweight piston engines or gas turbines. Powered aircraft have one or more engines. Flight control surfaces Main article: flight control surfaces Aircraft flight control surfaces allow a pilot to adjust and control the aircraft's flight attitude. Development of an effective set of flight controls was a critical advance in the development of aircraft. Early efforts at fixed-wing aircraft design succeeded in generating sufficient lift to get the aircraft off the ground, but once aloft, the aircraft proved uncontrollable, often with disastrous results. The development of effective flight controls is what allowed stable flight. Empennage Main article: Empennage Empennage The empennage of a Boeing 747-200 Empennage (pronounced /ˌɑːmpɨˈnɑːʒ/ or /ˈɛmpɨnɪdʒ/) is an aviation term used to describe the tail section of an aircraft.67 The empennage is also known as the tail or tail assembly; all three terms may be used interchangeably. The empennage gives stability to the aircraft and controls the flight dynamics of pitch and yaw.67 Flight deck Main article: cockpit Airbus A380 cockpit. Most Airbus cockpits are computerised glass cockpits featuring fly-by-wire technology. The control column has been replaced with an electronic sidestick. Swiss HB-IZX Saab 2000 cockpit Robin DR400/500 1936 De Havilland Hornet Moth cockpit A cockpit or flight deck is the area, usually near the front of an aircraft, from which a pilot controls the aircraft. Most modern cockpits are enclosed, except on some small aircraft, and cockpits on large airliners are also physically separated from the cabin. From the cockpit an aircraft is controlled on the ground and in the air. Cockpit as a term for the pilot's compartment in an aircraft first appeared in 1914. From about 1935 cockpit also came to be used informally to refer to the driver's seat of a car, especially a high performance one, and this is official terminology in Formula One. The term is most likely related to the sailing term for the coxswain's station in a Royal Navy ship, and later the location of the ship's rudder controls.citation needed The cockpit of an aircraft contains flight instruments on an instrument panel, and the controls which enable the pilot to fly the aircraft. In most airliners, a door separates the cockpit from the passenger compartment. After the September 11, 2001 terrorist attacks, all major airlines fortified the cockpit against access by hijackers. On an airliner, the cockpit is usually referred to as the flight deck. This term derives from its use by the RAF for the separate, upper platform where the pilot and co-pilot sat in large flying boats. Cabin Main article: Aircraft cabin An aircraft cabin is the section of an aircraft in which any passengers travel, often just called the cabin. At cruising altitudes, the surrounding atmosphere is too thin to breathe without an oxygen mask, so cabin pressurization adapts the cabin to atmospheric pressures. Performance of aircraft Flight envelope Main article: Flight envelope In aerodynamics, the flight envelope or performance envelope of an aircraft refers to the capabilities of a design in terms of airspeed and load factor or altitude.89 The term is somewhat loosely applied, and can also refer to other measurements such as maneuverability. When a plane is pushed, for instance by diving it at high speeds, it is said to be flown "outside the envelope", something considered rather dangerous. Flight envelope is one of a number of related terms that are all used in a similar fashion. It is perhaps the most common term because it is the oldest, first being used in the early days of test flying. It is closely related to more modern terms known as extra power and a doghouse plot which are different ways of describing a flight envelope. Aircraft range Main article: range (aircraft) The maximal total range is the distance an aircraft can fly between takeoff and landing, as limited by fuel capacity in powered aircraft, or cross-country speed and environmental conditions in unpowered aircraft. Ferry range means the maximum range the aircraft can fly. This usually means maximum fuel load, optionally with extra fuel tanks and minimum equipment. It refers to transport of aircraft for use on remote location. Combat range is the maximum range the aircraft can fly when carrying ordnance. 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. The fuel time limit for powered aircraft is fixed by the fuel load and rate of consumption. When all fuel is consumed, the engines stop and the aircraft will lose its propulsion. For unpowered aircraft, the maximum flight time is variable, limited by available daylight hours, weather conditions, and pilot endurance. The range can be seen as the cross-country ground speed multiplied by the maximum time in the air. The range equation will derived in this article for propeller and jet aircraft. Aircraft flight dynamics Main article: Flight dynamics (aircraft) 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 mass, known as pitch, roll and yaw (quite different from their use as Tait-Bryan angles). Aerospace engineers develop control systems for a vehicle's orientation (attitude) about its center of mass. The control systems include actuators, which exert forces in various directions, and generate rotational forces or moments about the aerodynamic center of the aircraft, and thus rotate the aircraft in pitch, roll, or yaw. For example, a pitching moment is a vertical force applied at a distance forward or aft from the aerodynamic center of the aircraft, causing the aircraft to pitch up or down. Roll, pitch and yaw refer to rotations about the respective axes starting from a defined equilibrium state. The equilibrium roll angle is known as wings level or zero bank angle, equivalent to a level heeling angle on a ship. Yaw is known as "heading". The equilibrium pitch angle in submarine and airship parlance is known as "trim", but in aircraft, this usually refers to angle of attack, rather than orientation. However, common usage ignores this distinction between equilibrium and dynamic cases. The most common aeronautical convention defines the roll as acting about the longitudinal axis, positive with the starboard (right) wing down. The yaw is about the vertical body axis, positive with the nose to starboard. Pitch is about an axis perpendicular to the longitudinal plane of symmetry, positive nose up.citation needed 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 usually streamlined from nose to tail to reduce drag making it typically advantageous to keep the sideslip angle near zero, though there are instances when an aircraft may be deliberately "sideslipped" for example a slip in a fixed wing aircraft.citation needed Areas of use The major distinction in aircraft types is between military aircraft, which includes not just combat types but many types of supporting aircraft, and civil aircraft, which include all non-military types. Saab Gripen, a Swedish multi-role fighter aircraft. Military Main article: Military aircraft A military aircraft is any fixed-wing or rotary-wing aircraft that is operated by a legal or insurrectionary armed service of any type.10 Military aircraft can be either combat or non-combat: Combat aircraft are aircraft designed to destroy enemy equipment using its own armament.10 Non-Combat aircraft are aircraft not designed for combat as their primary function, but may carry weapons for self-defense. Mainly operating in support roles. Combat aircraft divide broadly into fighters and bombers, with several in-between types such as fighter-bombers and ground-attack aircraft (including attack helicopters). Other supporting roles are carried out by specialist patrol, search and rescue, reconnaissance, observation, transport, training and Tanker aircraft among others. Many civil aircraft, both fixed-wing and rotary, have been produced in separate models for military use, such as the civil Douglas DC-3 airliner, which became the military C-47/C-53/R4D transport in the U.S. military and the "Dakota" in the UK and the Commonwealth. Even the small fabric-covered two-seater Piper J3 Cub had a military version, the L-4 liaison, observation and trainer aircraft. Gliders and balloons have also been used as military aircraft; for example, balloons were used for observation during the American Civil War and World War I, and military gliders were used during World War II to land troops. The Premium Class cabin of Jet Airways Boeing 777. Eurocopter EC 145 of the Rega air rescue service. Civil Main article: Civil aviation Civil aircraft divide into commercial and general types, however there are some overlaps. Commercial Main article: Commercial aviation Commercial aircraft include types designed for scheduled and charter airline flights, carrying both passengers and cargo. The larger passenger-carrying types are often referred to as airliners, the largest of which are wide-body aircraft. Some of the smaller types are also used in general aviation, and some of the larger types are used as VIP aircraft. General aviation Main article: General aviation General aviation is a catch-all covering other kinds of private and commercial use, and involving a wide range of aircraft types such as business jets (bizjets), trainers, homebuilt, aerobatic types, racers, gliders, warbirds, firefighters, medical transports, and cargo transports, to name a few. The vast majority of aircraft today are general aviation types. Within general aviation, there is a further distinction between private aviation (where the pilot is not paid for time or expenses) and commercial aviation (where the pilot is paid by a client or employer). The aircraft used in private aviation are usually light passenger, business, or recreational types, and are usually owned or rented by the pilot. The same types may also be used for a wide range of commercial tasks, such as flight training, pipeline surveying, passenger and freight transport, policing, crop dusting, and medical evacuations. However the larger, more complex aircraft are more likely to be found in the commercial sector. For example, piston-powered propeller aircraft (single-engine or twin-engine) are common for both private and commercial general aviation, but for aircraft such as turboprops like the Beechcraft King Air and helicopters like the Bell JetRanger, there are fewer private owners than commercial owners. Conventional business jets are most often flown by paid pilots, whereas the new generation of smaller jets are being produced for private pilots. Experimental Main article: Experimental aircraft Experimental aircraft are one-off specials, built to explore some aspect of aircraft design and with no other useful purpose. The Bell X-1 rocket plane, which first broke the sound barrier in level flight, is a famous example. A model aircraft, weighing six grams. Boeing B-17E in flight. The Allies of World War II lost 160,000 airmen and 33,700 planes during the air war over Europe.11 The formal designation of "experimental aircraft" also includes other types which are "not certified for commercial applications", including one-off modifications of existing aircraft such as the modified Boeing 747 which NASA uses to ferry the space shuttle from landing site to launch site, and aircraft homebuilt by amateurs for their own personal use. Model Main article: Model aircraft A model aircraft is a small unmanned type made to fly for fun, for static display, for aerodynamic research (cf Reynolds number) or for other purposes. A scale model is a replica of some larger design. Aircraft manufacture Manufacturers and types Within any general category, aircraft are usually listed according to manufacturer and production type. Also see: List of aircraft Aircraft design Main article: Aircraft design process The process of aircraft design has evolved during the last century.12 The early pioneers mainly used experimental designs with trial and error being used to determine what would work.13 The modern process is now more rigorous and risk averse as the cost of modern aircraft is high and the manufacturing process and resulting airframes are expected to be free of error and weakness14 See also Lists List of aircraft by category List of Airliners by Historical Epoch List of civil aircraft List of early flying machines List of helicopter models List of large aircraft List of military aircraft List of Regional Airliners List of World War II jet aircraft Aviation portal List of aircraft by date and usage category List of aircraft engines List of altitude records reached by different aircraft types List of aviation, aerospace and aeronautical terms Topics Air safety Airmail Airmails of the United States Air transports of Heads of State Aerial refuelling Aircraft design process Aircraft axis Aircraft carrier Aircraft spotting Airline call signs Aviation Balloon (aircraft) Cabin pressurization Contrail First flying machine   Flight controls Flight instruments Flight tracking Flight planning Flying car/roadable aircraft General aviation in Europe Gliding Loss of structural integrity on an aircraft Military aircraft Model rocket Noise pollution Personal air vehicle Powered parachute Powered paragliding   Pressure suit Rocket Rocket engine Rocket propellant Spacecraft Spaceflight Spaceplane Space Shuttle program Stealth aircraft Steam aircraft Surveillance aircraft Wide-body aircraft References ^ dictionary.com definition of aircraft ^ Mil Mi-26 Halo ^ Dee, Richard (2007). The Man who Discovered Flight: George Cayley and the First Airplane. Toronto: McClelland and Stewart. ISBN 978-0771029714.  ^ NASA's Beginners Guide to Aeronautics ^ Ed Rouen (2005). Airplane Names. San Diego Aerospace Museum. http://www.marchfield.org/rouen01.html.  Names and dates of more than 2,800 aircraft models produced since 1900. ^ a b Crane, Dale: Dictionary of Aeronautical Terms, third edition, page 194. Aviation Supplies & Academics, 1997. ISBN 1-56027-287-2 ^ a b Aviation Publishers Co. Limited, From the Ground Up, page 10 (27th revised edition) ISBN 09690054-9-0 ^ §23.333 Flight envelope ^ Flight envelope - diagram ^ a b Gunston 1986, p. 274 ^ Kenneth K. Hatfield (2003). "Heartland heroes: remembering World War II.". p.91. ^ Neil D. Van Sickle, John F. Welch, Lewis Bjork, Linda Bjork (1999), Van Sickle's modern airmanship, ISBN 9780070696334, http://books.google.co.uk/books?id=Ol-KVtOk_ZEC&pg=PA94  ^ Koen Frenken (2006), Innovation, evolution and complexity theory, http://books.google.co.uk/books?id=BZBg3GM4dpAC&pg=PA96  ^ Ajoy Kundu (2010), Aircraft Design, http://books.google.co.uk/books?id=NeHoahlhCGMC&pg=PA21  Gunston, Bill (1986). Jane's Aerospace Dictionary. London, England: Jane's Publishing Company Limited. ISBN 0 7106 0365 7.  External links Look up aircraft in Wiktionary, the free dictionary. Wikimedia Commons has media related to: Aircraft History History of Aviation in Australia - State Library of NSW Prehistory of Powered Flight The Channel Crossing The Evolution of Modern Aircraft (NASA) Virtual Museum Smithsonian Air and Space Museum – Online collection with a particular focus on history of aircraft and spacecraft New Scientist's History of Aviation Amazing Early Flying Machines slideshow by Life magazine Aircraft Types Information Airliners.net Aviation Dictionary Free aviation terms, phrases and jargons New Scientist's Aviation page v · d · eAircraft types Military aircraft ASW · Attack · AWACS · Bomber · Command and control · Cruise missile · Electronic warfare · Fighter · Patrol · Reconnaissance · Rescue · Tankers · Trainers · Transports · Utility Civil aircraft Agricultural · Airliners · Business · Cargo aircraft · Mailplanes · Sailplanes · Sport aircraft · Trainers · Ultralights · Utility · Trijets · Wide-body aircraft Miscellaneous Experimental aircraft · Seaplanes · Special-purpose v · d · eLists of aircraft By name 0-A · B · C · D · E-F · G-H · I–K · L · M · N–Q · R · S · T-Z By category Civil aircraft By type Fuselage characteristics Double-deck · Narrow-body · Wide-body Size characteristics Commercial civilian passenger fixed-wing aircraft airliners with more than 9 seats (After 2005) · "Boeing 747 Jumbo Jet" variants · Jumbo jets · Other "Jumbo jets" · Maximum Takeoff Weight Manufacturer Airbus airliners · Boeing Airliners · McDonnell Douglas Airliners Models Lockheed Constellation Number of engines Trijets · Trimotors · Twinjets · Aircraft engine position number Range Regional airliners · Short-haul civilian passenger aircraft post war · Short-haul jet airliners Aircraft uses Airliners · Light Transport · Regional airliner · Regional jet Unique features Flying wing · Gliders · Large a/c · Prone pilot · Seaplanes and amphibious Exploratory Early flying machines · Experimental · Rocket planes · X-planes Rotor powered Autogyros · Rotorcraft · Tiltrotors Executive or private transport Business jets · Light-sport aircraft · Personal aircraft · Roadable aircraft · VLJs Rigid airships Zeppelins By country of origin Sweden By manufacturer de Havilland · Lockheed · Parseval · Santos-Dumont · Schütte-Lanz By user Imperial Airways Other By date and usage · By tail number · Most produced Military aircraft By nation Argentina · Australia: RAAF - 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