Aircraft
An aircraft is a vehicle which is able to fly through the air (or through any other atmosphere). (Most rocket vehicles are not aircraft because they are not supported by the surrounding air). All the human activity which surrounds aircraft is called aviation.
Manned aircraft are flown by a pilot. Until ca. the 1960s, unmanned aircraft were called drones. During the 1960s, the US military brought the term remotely piloted vehicle (RPV) into use. More recently the term Unmanned Aerial Vehicle (UAV) has become common.
Manned aircraft are flown by a pilot. Until ca. the 1960s, unmanned aircraft were called drones. During the 1960s, the US military brought the term remotely piloted vehicle (RPV) into use. More recently the term Unmanned Aerial Vehicle (UAV) has become common.
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 lighter 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 — usually fixed-wing — though none had yet been built. The advent first of powered balloons, called dirigible balloons, and later of rigid hulls allowing a vast increase in size, began to change things. Huge powered aerostats, characterized by a rigid outer framework and separate aerodynamic skin surrounding the gas bags, came to dominate the skies, the Zeppelins being the largest and most famous. There were still no aeroplanes or non-rigid balloons large enough to be called airships, so "airship" came to be synonymous with these great monsters. Then several accidents, such as the Hindenburg disaster in 1937, led to the demise of these large rigid airships due to safety fears. Nowadays we say that 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 we tend to call any small dirigible or airship a blimp, though a blimp may be unpowered as well as powered.
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 — usually fixed-wing — though none had yet been built. The advent first of powered balloons, called dirigible balloons, and later of rigid hulls allowing a vast increase in size, began to change things. Huge powered aerostats, characterized by a rigid outer framework and separate aerodynamic skin surrounding the gas bags, came to dominate the skies, the Zeppelins being the largest and most famous. There were still no aeroplanes or non-rigid balloons large enough to be called airships, so "airship" came to be synonymous with these great monsters. Then several accidents, such as the Hindenburg disaster in 1937, led to the demise of these large rigid airships due to safety fears. Nowadays we say that 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 we tend to call any small dirigible or airship 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 aeroplanes kept in the air by the forward movement of wings, and rotorcraft by spinning wing-shaped rotors sometimes called rotary wings. 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, and its wings may be flexible or rigid, fixed or rotary. A wing is a flat, horizontal surface, usually shaped in cross-section as an aerofoil. To fly, the wing must move forwards through the air; this movement of air over the aerofoil shape deflects air downward to create an equal and opposite upward force, called lift, according to Newton's third law of motion.
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, take off and land vertically using powered lift and transfer to aerodynamic lift in steady flight. STOL stands for short take off and landing.
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.
Aerodynamic lift is the most common, with aeroplanes kept in the air by the forward movement of wings, and rotorcraft by spinning wing-shaped rotors sometimes called rotary wings. 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, and its wings may be flexible or rigid, fixed or rotary. A wing is a flat, horizontal surface, usually shaped in cross-section as an aerofoil. To fly, the wing must move forwards through the air; this movement of air over the aerofoil shape deflects air downward to create an equal and opposite upward force, called lift, according to Newton's third law of motion.
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, take off and land vertically using powered lift and transfer to aerodynamic lift in steady flight. STOL stands for short take off and landing.
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 aircraft
Aeroplanes or airplanes are technically called fixed-wing aircraft.
The forerunner of the aeroplane is the kite. A kite depends upon the tension between the cord which anchors it to the ground and the force of the wind currents. 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 most recently computer modelling programs became available.A collection of NASA test aircraft
Aeroplanes are generally characterized by their wing configuration.
In a conventional configuration, the main wings are placed in front of a smaller stabilizer surface or tailplane. The canard reverses this, placing a small foreplane stabilizer forward of the wings, near the nose of the aircraft. Canards are becoming more common as supersonic aerodynamics grows more mature and because the forward surface contributes lift during straight-and-level flight. The tandem wing type has two wings of similar size, one at the front and one at the back. In a tailless design, the lift and horizontal control surfaces are combined. The ultimate expression of this is the flying wing, where there is no central fuselage, and perhaps even no separate vertical control surface (e.g., the B-2 Spirit).
Sometimes two or more wings are stacked one above the other. A biplane has two wings and a triplane three, while quadruplanes (four) and above have been tried but have never been successful. Up until the 1930's, biplanes were the most common. Triplanes were only occasionally made, especially for a brief period during the First World War due to their high manoeuvrability as fighters. Since the Second World War, most aeroplanes have been monoplanes. A sesquiplane is similar to a biplane, but with the lower wing much reduced in size. A monoplane has only one wing. Monoplanes are further classified as high-wing, mid-wing or low-wing, according to where on the fuselage the wing is attached.
The forerunner of the aeroplane is the kite. A kite depends upon the tension between the cord which anchors it to the ground and the force of the wind currents. 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 most recently computer modelling programs became available.A collection of NASA test aircraft
Aeroplanes are generally characterized by their wing configuration.
In a conventional configuration, the main wings are placed in front of a smaller stabilizer surface or tailplane. The canard reverses this, placing a small foreplane stabilizer forward of the wings, near the nose of the aircraft. Canards are becoming more common as supersonic aerodynamics grows more mature and because the forward surface contributes lift during straight-and-level flight. The tandem wing type has two wings of similar size, one at the front and one at the back. In a tailless design, the lift and horizontal control surfaces are combined. The ultimate expression of this is the flying wing, where there is no central fuselage, and perhaps even no separate vertical control surface (e.g., the B-2 Spirit).
Sometimes two or more wings are stacked one above the other. A biplane has two wings and a triplane three, while quadruplanes (four) and above have been tried but have never been successful. Up until the 1930's, biplanes were the most common. Triplanes were only occasionally made, especially for a brief period during the First World War due to their high manoeuvrability as fighters. Since the Second World War, most aeroplanes have been monoplanes. A sesquiplane is similar to a biplane, but with the lower wing much reduced in size. A monoplane has only one wing. Monoplanes are further classified as high-wing, mid-wing or low-wing, according to where on the fuselage the wing is attached.
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.
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 through it, making it spin.(cf. Autorotation)US-Recognition Manual (very likely copy of german drawing)
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 most important characteristic is that in forward flight air does not flow significantly either up or down through the rotor disc but primarily across it. The Heliplane is a similar idea.
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.
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 through it, making it spin.(cf. Autorotation)US-Recognition Manual (very likely copy of german drawing)
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 most important characteristic is that in forward flight air does not flow significantly either up or down through the rotor disc but primarily across it. The Heliplane is a similar idea.
Other methods of lift
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 all the lift. Lifting bodies are not efficient: the aircraft must travel at high speed to generate enough lift to fly. The most famous lifting body design is the Space Shuttle, while some supersonic missiles obtain lift from the airflow over a tubular body.
Powered lifts rely entirely on engine thrust to hold them up in the air. 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). VTOL jet aircraft such as the Harrier jump-jet take off and land vertically in powered-lift configuration, then transition to conventional configuration for forward flight.
The FanWing is a recent innovation and represents a completely new class of aircraft. This 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 fan wing is (2005) in development in the United Kingdom.
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