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A powered aircraft is an
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
that uses onboard
propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...
with mechanical power generated by an
aircraft engine An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many ...
of some kind. Aircraft propulsion nearly always uses either a type of propeller, or a form of
jet propulsion Jet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operating o ...
. Other potential propulsion techniques such as
ornithopters An ornithopter (from Greek ''ornis, ornith-'' "bird" and ''pteron'' "wing") is an aircraft that flies by flapping its wings. Designers sought to imitate the flapping-wing flight of birds, bats, and insects. Though machines may differ in form, t ...
are very rarely used.


Methods of propulsion


Rotating aerofoils


Propeller aircraft

A
propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...
or airscrew comprises a set of small, wing-like aerofoil ''blades'' set around a central hub which spins on an axis aligned in the direction of travel. The blades are set at a '' pitch'' angle to the airflow, which may be fixed or variable, such that spinning the propeller creates aerodynamic lift, or ''thrust'', in a forward direction. A ''
tractor A tractor is an engineering vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a trailer or machinery such as that used in agriculture, mining or construction. Most common ...
'' 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 Weight distribution is the apportioning of weight within a vehicle, especially cars, airplanes, and trains. Typically, it is written in the form ''x''/''y'', where ''x'' is the percentage of weight in the front, and ''y'' is the percentage in the ...
. ''
Contra-rotating propellers Aircraft equipped with contra-rotating propellers, also referred to as CRP, coaxial contra-rotating propellers, or high-speed propellers, apply the maximum power of usually a single piston or turboprop engine to drive a pair of coaxial propell ...
'' have one propeller close behind another on the same axis, but rotating in the opposite direction. A variation on the propeller is to use many broad blades to create a fan. Such fans are usually surrounded by a ring-shaped fairing or duct, as ''
ducted fan In aeronautics, a ducted fan is a thrust-generating mechanical fan or propeller mounted within a cylindrical duct or shroud. Other terms include ducted propeller or shrouded propeller. When used in vertical takeoff and landing (VTOL) applicatio ...
s''. Many kinds of power plant have been used to drive propellers. The earliest designs used
man power ''Man Power'' is a lost 1927 American comedy silent film directed by Clarence G. Badger and written by Ray Harris, Louise Long, George Marion Jr., Sam Mintz and Byron Morgan. The film stars Richard Dix and features Mary Brian, Philip Strange, ...
to give
dirigible An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air. In early ...
balloons some degree of control, and go back to
Jean-Pierre Blanchard Jean-Pierre rançoisBlanchard (4 July 1753 – 7 March 1809) was a French inventor, best known as a pioneer of gas balloon flight, who distinguished himself in the conquest of the air in a balloon, in particular the first crossing of the Englis ...
in 1784. Attempts to achieve heavier-than-air man-powered flight did not succeed fully until
Paul MacCready Paul B. MacCready Jr. (September 25, 1925 – August 28, 2007) was an American aeronautical engineer. He was the founder of AeroVironment and the designer of the human-powered aircraft that won the first Kremer prize. He devoted his life to dev ...
's
Gossamer Condor The MacCready ''Gossamer Condor'' was the first human-powered aircraft capable of controlled and sustained flight; as such, it won the Kremer prize in 1977. Its design was led by Paul MacCready of AeroVironment, Inc. Design and development ...
in 1977. The first powered flight of an aircraft was made in a
steam-powered A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be tr ...
dirigible by
Henri Giffard Baptiste Jules Henri Jacques Giffard (8 February 182514 April 1882) was a French engineer. In 1852 he invented the steam injector and the powered Giffard dirigible airship. Career Giffard was born in Paris in 1825. He invented the injector a ...
in 1852. Attempts to marry a practical lightweight
steam engine A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be trans ...
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 powered fixed-wing aircraft flight by
William Frost William Frost (28 May 1848 – March 1935) was a Welsh designer of an early flying machine, the Frost Airship Glider. Biography William Frost was born on 28 May 1848 in Saundersfoot, Pembrokeshire, to Rebecca and John Frost. His ambition ...
until
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, propellers turned by the
internal combustion piston engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combust ...
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 A turboprop is a turbine engine that drives an aircraft propeller. A turboprop consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling nozzle. Air enters the intake and is compressed by the compressor. Fuel ...
. 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 mount the propeller directly on an engine turbine shaft, and are called
propfan A propfan, also called an open rotor engine, or unducted fan (as opposed to a ducted fan), is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed an ...
s. Other less common power sources include: *Electric motors, often used for short range applications such a
front electric sustainer Front electric sustainer (FES) is a propulsion system for gliders that uses an electric motor powered by batteries and a foldable propeller. It is produced by LZ Design d.o.o. in Logatec, Slovenia. The system uses a 22 kW compact outrunner ...
engines for gliders and other types of electric aircraft. Some experimental types use solar panels to create a
solar-powered aircraft An electric aircraft is an aircraft powered by electricity. Electric aircraft are seen as a way to reduce the environmental effects of aviation, providing zero emissions and quieter flights. Electricity may be supplied by a variety of methods ...
. *Rubber bands, wound many times to store energy, are mostly used for flying models.


Rotorcraft

Rotorcraft have spinning blades called a ''rotor'' which spins in the horizontal plane to provide lift. Forward thrust is usually obtained by angling the rotor disc slightly forward so that a proportion of its lift is directed backwards; these are called
helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...
s. Other rotorcraft are
compound helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...
s and
autogyro An autogyro (from Greek and , "self-turning"), also known as a ''gyroplane'', is a type of rotorcraft that uses an unpowered rotor in free autorotation to develop lift. Forward thrust is provided independently, by an engine-driven propeller. Whi ...
s which sometimes use other means of propulsion, such as propellers and jets. 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 jet A tip jet is a jet nozzle at the tip of some helicopter rotor blades, used to spin the rotor, much like a Catherine wheel firework. Tip jets replace the normal shaft drive and have the advantage of placing no torque on the airframe, thus not r ...
s, 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.


Jet propulsion


Jet aircraft

Airbreathing jet engine An airbreathing jet engine (or ''ducted jet engine'') is a jet engine that ejects a propelling (reaction) jet of hot exhaust gases after first taking in atmospheric air, followed by compression, heating and expansion back to atmospheric pressure ...
s provide thrust by taking in air, compressing the air, injecting fuel into the hot compressed air mixture in a
combustion chamber A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process. Interna ...
, the resulting accelerated exhaust ejects rearwards through a turbine which drives the compressor. 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 . They are also much more fuel-efficient at normal flight speeds than
rocket A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely fr ...
s. Consequently, nearly all high-speed and high-altitude aircraft use jet engines. The early
turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
and modern
turbofan The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...
use a spinning compressor and turbine to provide thrust. Many, mostly in military aviation, add an
afterburner An afterburner (or reheat in British English) is an additional combustion component used on some jet engines, mostly those on military supersonic aircraft. Its purpose is to increase thrust, usually for supersonic flight, takeoff, and comba ...
which injects extra fuel into the hot exhaust. Use of a turbine is not absolutely necessary: other designs include the crude
pulse jet 300px, Diagram of a pulsejet A pulsejet engine (or pulse jet) is a type of jet engine in which combustion occurs in pulses. A pulsejet engine can be made with few or no moving parts, and is capable of running statically (i.e. it does not need ...
, high-speed
ramjet A ramjet, or athodyd (aero thermodynamic duct), is a form of airbreathing jet engine that uses the forward motion of the engine to produce thrust. Since it produces no thrust when stationary (no ram air) ramjet-powered vehicles require an ass ...
and the still-experimental supersonic-combustion ramjet or
scramjet A scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully ...
. These mechanically simple 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 turbo-ramjet J58 engines of the
Lockheed SR-71 The Lockheed SR-71 "Blackbird" is a long-range, high-altitude, Mach 3+ strategic reconnaissance aircraft developed and manufactured by the American aerospace company Lockheed Corporation. It was operated by the United States Air Force ...
were a hybrid design – the aircraft took off and landed in pure jet turbine configuration, and for high-speed flight the afterburner was lit and the turbine bypassed, with 90% of the mass of airflow going around it, to create a ramjet. Some air is still required to go thru the core to sustain operation and retain power from generators and hydraulic pumps to aircraft systems The
motorjet A motorjet is a rudimentary type of jet engine which is sometimes referred to as ''thermojet'', a term now commonly used to describe a particular and completely unrelated pulsejet design. Design At the heart the motorjet is an ordinary pis ...
was a very early design which used a piston engine in place of the combustion chamber, similar to a
turbocharged In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...
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.


Rocket-powered aircraft

Rocket A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely fr ...
propulsion offers very high thrust for light weight and has no height limit, but suffers from high fuel consumption and the need to carry oxidant as well as propellant. Rocket-powered aircraft have been experimented with, and during the Second World War the Messerschmitt ''Komet'' fighter was developed and used operationally. Since then they have been restricted to specialised niches, such as the
Bell X-1 The Bell X-1 (Bell Model 44) is a rocket engine–powered aircraft, designated originally as the XS-1, and was a joint National Advisory Committee for Aeronautics– U.S. Army Air Forces–U.S. Air Force supersonic research project built by Be ...
which broke the sound barrier or the North American X-15 which was capable of flying at extremely high altitudes at the border with space as it was not dependent on atmospheric oxygen. Rockets have more often been used as a supplement to the main powerplant, typically in the case of
rocket-assisted take off JATO (acronym for jet-assisted take-off) is a type of assisted take-off for helping overloaded aircraft into the air by providing additional thrust in the form of small rockets. The term ''JATO'' is used interchangeably with the (more specific ...
to give more power for a heavily loaded aircraft or reduce the takeoff run. In a number of designs such as the prototype "mixed-power"
Saunders-Roe SR.53 The Saunders-Roe SR.53 was a British prototype interceptor aircraft of mixed jet and rocket propulsion developed for the Royal Air Force (RAF) by Saunders-Roe in the early 1950s. As envisaged, the SR.53 would have been used as an interceptor a ...
interceptor Interceptor may refer to: Vehicles * Interceptor aircraft (or simply "interceptor"), a type of point defense fighter aircraft designed specifically to intercept and destroy enemy aircraft * Ford Crown Victoria Police Interceptor, a police car * ...
a rocket was used to provide high-speed climb and speed to reach the target while a smaller turbojet provided a slower and more economical return to base.


Ornithopter

The ornithopter obtains thrust by flapping its wings. When the wing flaps, as opposed to gliding, it continues to develop lift as before, but the lift is rotated forward to provide a
thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that syst ...
component. Working devices have been created for flight research and as prototypes, but the vertical oscillation of the fuselage, which tends to accompany the wing flapping, limits their usefulness. The only practical application is a flying model hawk used to freeze prey animals into stillness so that they can be captured. Toys in the form of a flying model bird are also popular.


Methods of powering lift

A
fixed-wing aircraft A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinc ...
obtains lift from airflow over the wing resulting from motion due to forward thrust. A few other types, such as the rotary-winged
autogyro An autogyro (from Greek and , "self-turning"), also known as a ''gyroplane'', is a type of rotorcraft that uses an unpowered rotor in free autorotation to develop lift. Forward thrust is provided independently, by an engine-driven propeller. Whi ...
, obtain lift through similar methods. Some types use a separate power system to create lift. These include the rotary-winged
helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...
and craft that use
lift jet {{Unreferenced, date=July 2009 A lift jet is a jet engine angled to provide an aircraft with ''aerostatic'' (i.e. not requiring the movement of air over an airfoil) lift, instead of (or in addition to) thrust. On a fixed-wing aircraft, lift jets ...
s (e.g. the
flying bedstead Flying may refer to: * Flight, the process of flying * Aviation, the creation and operation of aircraft Music Albums * ''Flying'' (Grammatrain album), 1997 * ''Flying'' (Jonathan Fagerlund album), 2008 * ''Flying'' (UFO album), 1971 * ''Fl ...
). A
hot air balloon A hot air balloon is a lighter-than-air aircraft consisting of a bag, called an envelope, which contains heated air. Suspended beneath is a gondola or wicker basket (in some long-distance or high-altitude balloons, a capsule), which carries p ...
requires a power source (normally a gas burner) for lift, but is not normally considered a "powered aircraft".


See also

*
Nuclear-powered aircraft A nuclear-powered aircraft is a concept for an aircraft intended to be powered by nuclear energy. The intention was to produce a jet engine that would heat compressed air with heat from fission, instead of heat from burning fuel. During the Co ...
*
Unpowered aircraft Unpowered aircraft can remain airborne for a significant period of time without onboard propulsion. They can be classified as fixed-wing gliders, lighter-than-air balloons and tethered kites. This requires a trajectory that is not merely a verti ...
* Jet-Assisted Takeoff


References


External links


Prehistory of Powered Flight
(U.S. Centennial of Flight Commission) {{DEFAULTSORT:Powered Aircraft Propulsion
Aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...