Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Aircraft shopping experience:

1. Compare - without doubt the biggest advantage that the Aircraft offers shoppers today is the ability to compare thousands of Aircraft at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Aircraft? Wrong! If the Aircraft is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Aircraft then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Aircraft? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Aircraft and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Aircraft wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Aircraft then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Aircraft site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Aircraft, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Aircraft, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.



An aircraft is a vehicle which is able to flight through the Earth's atmosphere (or through any other atmosphere). All the human activity which surrounds aircraft is called aviation. (Most rocket vehicles are not aircraft because they are not supported by the surrounding air).

Manned aircraft are flown by a pilot. Unmanned aircraft are traditionally called drones, while the term RPV (remote piloted vehicle) has recently become common in modern military circles.

, the world's largest passenger airliner

Different kinds of aircraft Aircraft fall into two broad categories: Lighter-than-air, called aerostats, and heavier-than-air, called aerodynes.

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 balloon, 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 Kongming lantern 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 airship 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 all our large and impressive aircraft are aeroplanes rather than rigid aerostats, and we are no longer so impressed by size; we say that a balloon (aircraft) 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, while it is often forgotten that 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: aerodynamics, 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. A wing is a flat, horizontal surface, usually shaped in cross-section as an aerofoil. To fly it 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 laws of motion.

With powered lift, the aircraft directs its engine thrust vertical direction downwards. 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.

The Acronym and 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.

Aeroplanes (largest airliner), the Boeing 747Boeing 747-8, the Antonov An-225 (aircraft with the greatest payload) and the Hughes H-4 Hercules (aircraft with greatest wingspan).

Aeroplanes or Airplanes are technically called fixed-wing aircraft.

The forerunner of the aeroplane is the Kite flying. 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.

test aircraft

Aeroplanes are generally characterised by their wing configuration.

In a conventional configuration, the main wings are placed in front of a smaller stabilizer surface or tailplane. The Canard (aeronautics) reverses this, placing a small foreplane 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 aircraft 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 has three, quadruplanes (four) and above 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. Most multi-plane designs are braced, with struts and/or wires holding the wings in place. A monoplane has only one wing. Some, especially early designs, are also braced, because this allows a much lighter weight than a clean, unbraced cantilever design. But bracing causes a large amount of drag at higher speeds, so it is no longer used for faster designs. Monoplanes are also classified as high-wing, mid-wing or low-wing, according to where on the fuselage the wing is attached.

Most low-speed aeroplanes have a straight wing, which may be constant-chord, or tapered so that it decreases in chord towards the tip. For flight near or above the speed of sound, a swept wing is usually used, where the wing angles backwards towards the tips (though forward sweep is occasionally experimented with, and M-wing designs which reverse direction half way along have been suggested). A notable variation is the delta wing wing, which is shaped like a triangle: the leading edge is sharply swept, but the trailing edge is straight; one common form is the cropped delta, which merges into the tapered swept category, and an especially graceful form is the double-curved ogival delta found for example on Concorde. Another variation is the crescent wing, seen for example on the Handley Page Victor, which is sharply swept inboard, with reduced sweep for the outboard section. A variable-geometry wing, or swing-wing, can change the angle of sweep in flight. It has been employed in a few examples of combat aircraft, the first production type being the General Dynamics F-111.

Seaplanes and Floatplanes differ in that a seaplane has the bottom of its fuselage shaped hydrodynamically and it sits directly on the water when at rest, while a floatplane has two or more floats attached below the rest of the aircraft so that the fuselage remains clear of the water at all times.

Some people consider Wing In Ground vehicles to be aeroplanes, others do not. These craft "fly" close to the surface of the ground or water. An example is the Russian ekranoplan also nicknamed the "Caspian Sea Monster". Human-powered flight 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. (Hovercraft are not considered to be aircraft, since they rely wholly on the pressure of air on the ground beneath, and have no aerodynamic lifting surface).

Rotorcraft helicopter

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. This spinning dramatically increases the speed of airflow over the rotor, to provide lift. Juan de la Cierva used the product name autogiro, and Bensen Aircraft 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 speed.

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.

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. 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 aeroplane 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





Propulsion Unpowered Some types of aircraft, such as balloons, kites and gliders, do not have any propulsion.

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).

Kites are tethered to the ground, and rely on wind blowing over them to generate lift.

Gliders gain their initial thrust from some launch mechanism, and then gain energy from gravity and thermal currents. Takeoff takes place from a high location, or the aircraft is pulled into the air by a ground-based winch or vehicle, or towed aloft 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). The first practical example was designed and built by the British scientist and pioneer George Cayley who is universally recognised as the first aeronautical engineer.

Propeller driven -engined De Havilland Canada DHC-6 Twin Otter adapted as a Seaplane

A propeller comprises a set of small, wing-like aerofoils set around a central hub and aligned in the direction of travel. Spinning the propeller creates aerodynamic lift, or thrust, in a forward direction. A contra-prop arrangement has a second propeller close behind the first one on the same axis, which rotates in the opposite direction.

Some very early attempts were made to make lightweight steam engines capable of powering an aircraft. There is some evidence that (name needed) may have succeeded in making a flying model, but this has never been confirmed.

From the first powered flight by the Wright brothers until World War II, propellers turned by the Internal combustion engine were virtually the only type of propulsion system in use. (See also: Aircraft engine.) The piston engine is still used in the majority of smaller aircraft produced, since it is efficient at the lower altitudes used by these aircraft, but the radial engine (with the cylinders arranged in a circle around the crankshaft) has largely given way to the horizontally-opposed engine (with the cylinders lined up on two sides of the crankshaft). Water cooled V engines, as used in automobiles, were common in high speed aircraft, until they were replaced by jet and turbine power. Piston engines typically operate using avgas or regular gasoline, though some new ones are being designed to operate on diesel or jet fuel. Piston engines normally become less efficient above 7,000-8,000 ft (2100-2400 m) above sea level because there is less oxygen available for combustion; to solve that problem, some piston engines have mechanically powered compressors (blowers) or turbine-powered turbochargers or turbonormalizers that compress the air before feeding it into the engine; these piston engines can often operate efficiently at 20,000 ft (6100 m) above sea level or higher, altitudes that require the use of supplemental oxygen or cabin pressurization.

, a Human-powered transport aircraft

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.

Other less common power sources include:







A variation on propellers is to use many broad blades to create a fan. These fans are traditionally surrounded by a ring-shaped fairing or duct, as ducted fans. Some experimental designs do not use a duct, and are sometimes called propfans. How to tell whether it's a propellor or a fan? Look at it from the front when stationary: if you can see in between the blades then it is a propellor, while if the blades pretty much block the view it is a fan.

During the 1940's and especially following the 1973 energy crisis, development work was done on propellers and propfans with swept tips or even curved "scimitar-shaped" blades for use in high-speed commercial and military transports.

Jet engines Jet engines provide thrust by taking in air, burning it with fuel, and accelerating the exhaust rearwards so that it ejects at high speed. The reaction against this acceleration provides the engine thrust.

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 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, but this 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 engines of the SR-71 Blackbird were a hybrid design - the aircraft took off and landed in jet turbine configuration, and for high-speed flight the turbine was bypassed to form a ramjet. The motorjet used a piston engine in place of the turbine - it was superseded by the turbojet and remained a curiosity.

Other forms of propulsion



Classification by use The major distinction in aircraft usage is between military aviation, which includes all uses of aircraft for military purposes (such as combat, patrolling, search and rescue, reconnaissance, transport, and training), and civil aviation, which includes all uses of aircraft for non-military purposes.

Military aircraft

Combat aircraft like fighters or bombers represent only a minority of the category. Many civil aircraft have been produced in separate models for military use, such as the civil Douglas DC-3 airliner, which became the military C-47 Skytrain/C-53/R4D transport in the U.S. military and the "Dakota" in the UK and the Commonwealth of Nations. Even the small fabric-covered two-seater Piper Cub had a military version, the L-4 liaison, observation and trainer aircraft. In the past, 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 cargo gliders were used during World War II to land troops.

Combat aircraft themselves, though used a handful of times for reconnaissance and surveillance aircraft during the Italo-Turkish War, did not come into widespread use until the Balkan War.

During World War I many types of aircraft were adapted for attacking the ground or enemy vehicles/ships/guns/aircraft, and the first aircraft designed as bombers were born. In order to prevent the enemy from bombing, fighter aircraft were developed to intercept and shoot down enemy aircraft. Tanker (aircraft) were developed after World War II to refuel other aircraft in mid-air, thus increasing their operational range. By the time of the Vietnam War, helicopters had come into widespread military use, especially for transporting, supplying, and supporting ground troops.

Civil aircraft of Qatar Airways flight

Civil aviation broadly divides into commercial and general activities, however there can be some overlap in practice.

Commercial aircraft Commercial aviation includes scheduled and charter airline flights. It also overlaps with a certain amount of general aviation activity where aircraft are offered for hire.

General aviation General aviation is a catch-all covering other kinds of private and commercial use. The vast majority of flights flown around the world each day belong to the general aviation category, which covers a wide range of activities such as business trips, civilian flight training, recreational balloon flying, firefighting, medical transport (medevac) flights, and cargo transportation on freight aircraft, to name a few. Within general aviation, the major distinction is between private flights (where the pilot is not paid for time or expenses) and commercial flights (where the pilot is paid by a customer or employer). Private pilots use aircraft primarily for personal travel, business travel, or recreation. Usually these private pilots own their own aircraft and take out loans from banks or specialized lenders to purchase them. Commercial general aviation pilots use aircraft for a wide range of tasks, such as flight training, pipeline surveying, passenger and freight transport, policing, crop dusting, and medevac flights. Piston-powered propeller aircraft (single-engine or twin-engine) are especially common for both private and commercial general aviation, but even private pilots occasionally own and operate helicopters like the Bell 206 or turboprops like the Beechcraft King Air. Business jets are typically flown by commercial pilots, although there is a new generation of small jets arriving soon for private pilots.

Experimental aircraft These aircraft are one-off specials, built to explore some aspect of aircraft design and with no other useful purpose.

Model aircraft A model aircraft is a small copy of some larger aircraft design. Models may be made to fly for fun, for static display, or for serious aerodynamic research (cf Reynolds number).

History See also: Timeline of aviation

The history of aircraft development divides broadly into five eras:

Manufacturers and types Within any general category, aircraft are usually listed according to manufacturer and production type. See also: List of aircraft

Environmental effects Aircraft generate considerable amounts of noise pollution and airpollution emissions Since the 1960s the U S Environmental Protection Agency has developed emissions factors for the most commonly used aircraft; in 1972 the Federal Aviation Administration developed a computer model for prediction of air pollution concentrations produced by aircraft in flightHogan, C Michael, Richard Venti and Leda Patmore, Prediction of aircraft generated air pollution contours, ESL Inc, prepared for the U S Federal Aviation Administration 1971

See also Lists

Topics

References

External links History

Information



An aircraft is a vehicle which is able to flight through the Earth's atmosphere (or through any other atmosphere). All the human activity which surrounds aircraft is called aviation. (Most rocket vehicles are not aircraft because they are not supported by the surrounding air).

Manned aircraft are flown by a pilot. Unmanned aircraft are traditionally called drones, while the term RPV (remote piloted vehicle) has recently become common in modern military circles.

, the world's largest passenger airliner

Different kinds of aircraft Aircraft fall into two broad categories: Lighter-than-air, called aerostats, and heavier-than-air, called aerodynes.

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 balloon, 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 Kongming lantern 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 airship 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 all our large and impressive aircraft are aeroplanes rather than rigid aerostats, and we are no longer so impressed by size; we say that a balloon (aircraft) 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, while it is often forgotten that 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: aerodynamics, 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. A wing is a flat, horizontal surface, usually shaped in cross-section as an aerofoil. To fly it 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 laws of motion.

With powered lift, the aircraft directs its engine thrust vertical direction downwards. 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.

The Acronym and 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.

Aeroplanes (largest airliner), the Boeing 747Boeing 747-8, the Antonov An-225 (aircraft with the greatest payload) and the Hughes H-4 Hercules (aircraft with greatest wingspan).

Aeroplanes or Airplanes are technically called fixed-wing aircraft.

The forerunner of the aeroplane is the Kite flying. 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.

test aircraft

Aeroplanes are generally characterised by their wing configuration.

In a conventional configuration, the main wings are placed in front of a smaller stabilizer surface or tailplane. The Canard (aeronautics) reverses this, placing a small foreplane 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 aircraft 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 has three, quadruplanes (four) and above 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. Most multi-plane designs are braced, with struts and/or wires holding the wings in place. A monoplane has only one wing. Some, especially early designs, are also braced, because this allows a much lighter weight than a clean, unbraced cantilever design. But bracing causes a large amount of drag at higher speeds, so it is no longer used for faster designs. Monoplanes are also classified as high-wing, mid-wing or low-wing, according to where on the fuselage the wing is attached.

Most low-speed aeroplanes have a straight wing, which may be constant-chord, or tapered so that it decreases in chord towards the tip. For flight near or above the speed of sound, a swept wing is usually used, where the wing angles backwards towards the tips (though forward sweep is occasionally experimented with, and M-wing designs which reverse direction half way along have been suggested). A notable variation is the delta wing wing, which is shaped like a triangle: the leading edge is sharply swept, but the trailing edge is straight; one common form is the cropped delta, which merges into the tapered swept category, and an especially graceful form is the double-curved ogival delta found for example on Concorde. Another variation is the crescent wing, seen for example on the Handley Page Victor, which is sharply swept inboard, with reduced sweep for the outboard section. A variable-geometry wing, or swing-wing, can change the angle of sweep in flight. It has been employed in a few examples of combat aircraft, the first production type being the General Dynamics F-111.

Seaplanes and Floatplanes differ in that a seaplane has the bottom of its fuselage shaped hydrodynamically and it sits directly on the water when at rest, while a floatplane has two or more floats attached below the rest of the aircraft so that the fuselage remains clear of the water at all times.

Some people consider Wing In Ground vehicles to be aeroplanes, others do not. These craft "fly" close to the surface of the ground or water. An example is the Russian ekranoplan also nicknamed the "Caspian Sea Monster". Human-powered flight 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. (Hovercraft are not considered to be aircraft, since they rely wholly on the pressure of air on the ground beneath, and have no aerodynamic lifting surface).

Rotorcraft helicopter

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. This spinning dramatically increases the speed of airflow over the rotor, to provide lift. Juan de la Cierva used the product name autogiro, and Bensen Aircraft 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 speed.

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.

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. 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 aeroplane 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





Propulsion Unpowered Some types of aircraft, such as balloons, kites and gliders, do not have any propulsion.

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).

Kites are tethered to the ground, and rely on wind blowing over them to generate lift.

Gliders gain their initial thrust from some launch mechanism, and then gain energy from gravity and thermal currents. Takeoff takes place from a high location, or the aircraft is pulled into the air by a ground-based winch or vehicle, or towed aloft 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). The first practical example was designed and built by the British scientist and pioneer George Cayley who is universally recognised as the first aeronautical engineer.

Propeller driven -engined De Havilland Canada DHC-6 Twin Otter adapted as a Seaplane

A propeller comprises a set of small, wing-like aerofoils set around a central hub and aligned in the direction of travel. Spinning the propeller creates aerodynamic lift, or thrust, in a forward direction. A contra-prop arrangement has a second propeller close behind the first one on the same axis, which rotates in the opposite direction.

Some very early attempts were made to make lightweight steam engines capable of powering an aircraft. There is some evidence that (name needed) may have succeeded in making a flying model, but this has never been confirmed.

From the first powered flight by the Wright brothers until World War II, propellers turned by the Internal combustion engine were virtually the only type of propulsion system in use. (See also: Aircraft engine.) The piston engine is still used in the majority of smaller aircraft produced, since it is efficient at the lower altitudes used by these aircraft, but the radial engine (with the cylinders arranged in a circle around the crankshaft) has largely given way to the horizontally-opposed engine (with the cylinders lined up on two sides of the crankshaft). Water cooled V engines, as used in automobiles, were common in high speed aircraft, until they were replaced by jet and turbine power. Piston engines typically operate using avgas or regular gasoline, though some new ones are being designed to operate on diesel or jet fuel. Piston engines normally become less efficient above 7,000-8,000 ft (2100-2400 m) above sea level because there is less oxygen available for combustion; to solve that problem, some piston engines have mechanically powered compressors (blowers) or turbine-powered turbochargers or turbonormalizers that compress the air before feeding it into the engine; these piston engines can often operate efficiently at 20,000 ft (6100 m) above sea level or higher, altitudes that require the use of supplemental oxygen or cabin pressurization.

, a Human-powered transport aircraft

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.

Other less common power sources include:







A variation on propellers is to use many broad blades to create a fan. These fans are traditionally surrounded by a ring-shaped fairing or duct, as ducted fans. Some experimental designs do not use a duct, and are sometimes called propfans. How to tell whether it's a propellor or a fan? Look at it from the front when stationary: if you can see in between the blades then it is a propellor, while if the blades pretty much block the view it is a fan.

During the 1940's and especially following the 1973 energy crisis, development work was done on propellers and propfans with swept tips or even curved "scimitar-shaped" blades for use in high-speed commercial and military transports.

Jet engines Jet engines provide thrust by taking in air, burning it with fuel, and accelerating the exhaust rearwards so that it ejects at high speed. The reaction against this acceleration provides the engine thrust.

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 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, but this 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 engines of the SR-71 Blackbird were a hybrid design - the aircraft took off and landed in jet turbine configuration, and for high-speed flight the turbine was bypassed to form a ramjet. The motorjet used a piston engine in place of the turbine - it was superseded by the turbojet and remained a curiosity.

Other forms of propulsion



Classification by use The major distinction in aircraft usage is between military aviation, which includes all uses of aircraft for military purposes (such as combat, patrolling, search and rescue, reconnaissance, transport, and training), and civil aviation, which includes all uses of aircraft for non-military purposes.

Military aircraft

Combat aircraft like fighters or bombers represent only a minority of the category. Many civil aircraft have been produced in separate models for military use, such as the civil Douglas DC-3 airliner, which became the military C-47 Skytrain/C-53/R4D transport in the U.S. military and the "Dakota" in the UK and the Commonwealth of Nations. Even the small fabric-covered two-seater Piper Cub had a military version, the L-4 liaison, observation and trainer aircraft. In the past, 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 cargo gliders were used during World War II to land troops.

Combat aircraft themselves, though used a handful of times for reconnaissance and surveillance aircraft during the Italo-Turkish War, did not come into widespread use until the Balkan War.

During World War I many types of aircraft were adapted for attacking the ground or enemy vehicles/ships/guns/aircraft, and the first aircraft designed as bombers were born. In order to prevent the enemy from bombing, fighter aircraft were developed to intercept and shoot down enemy aircraft. Tanker (aircraft) were developed after World War II to refuel other aircraft in mid-air, thus increasing their operational range. By the time of the Vietnam War, helicopters had come into widespread military use, especially for transporting, supplying, and supporting ground troops.

Civil aircraft of Qatar Airways flight

Civil aviation broadly divides into commercial and general activities, however there can be some overlap in practice.

Commercial aircraft Commercial aviation includes scheduled and charter airline flights. It also overlaps with a certain amount of general aviation activity where aircraft are offered for hire.

General aviation General aviation is a catch-all covering other kinds of private and commercial use. The vast majority of flights flown around the world each day belong to the general aviation category, which covers a wide range of activities such as business trips, civilian flight training, recreational balloon flying, firefighting, medical transport (medevac) flights, and cargo transportation on freight aircraft, to name a few. Within general aviation, the major distinction is between private flights (where the pilot is not paid for time or expenses) and commercial flights (where the pilot is paid by a customer or employer). Private pilots use aircraft primarily for personal travel, business travel, or recreation. Usually these private pilots own their own aircraft and take out loans from banks or specialized lenders to purchase them. Commercial general aviation pilots use aircraft for a wide range of tasks, such as flight training, pipeline surveying, passenger and freight transport, policing, crop dusting, and medevac flights. Piston-powered propeller aircraft (single-engine or twin-engine) are especially common for both private and commercial general aviation, but even private pilots occasionally own and operate helicopters like the Bell 206 or turboprops like the Beechcraft King Air. Business jets are typically flown by commercial pilots, although there is a new generation of small jets arriving soon for private pilots.

Experimental aircraft These aircraft are one-off specials, built to explore some aspect of aircraft design and with no other useful purpose.

Model aircraft A model aircraft is a small copy of some larger aircraft design. Models may be made to fly for fun, for static display, or for serious aerodynamic research (cf Reynolds number).

History See also: Timeline of aviation

The history of aircraft development divides broadly into five eras:

Manufacturers and types Within any general category, aircraft are usually listed according to manufacturer and production type. See also: List of aircraft

Environmental effects Aircraft generate considerable amounts of noise pollution and airpollution emissions Since the 1960s the U S Environmental Protection Agency has developed emissions factors for the most commonly used aircraft; in 1972 the Federal Aviation Administration developed a computer model for prediction of air pollution concentrations produced by aircraft in flightHogan, C Michael, Richard Venti and Leda Patmore, Prediction of aircraft generated air pollution contours, ESL Inc, prepared for the U S Federal Aviation Administration 1971

See also Lists

Topics

References

External links History

Information



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