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Aircraft engine – Wikipedia

Engine designed for use in powered aircraft
” Aero-engine ” redirects here. For the use of aircraft engines in car rental in hanoi
s, see Aero-engined car

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 small UAVs have used electric motors.

Manufacturing industry[edit]

In commercial aviation the major Western manufacturers of turbofan engines are Pratt và Whitney ( a subsidiary of Raytheon Technologies ), General Electric, Rolls-Royce, và CFM International ( a joint venture of Safran Aircraft Engines và General Electric ). Russian manufacturers include the United Engine Corporation, Aviadvigatel & Klimov. Aeroengine Corporation of Trung Quốc was formed in năm nay with the merger of several smaller companies. [ một ]The largest manufacturer of turboprop engines for general aviation is Pratt và Whitney. [ 2 ] General Electric announced in năm ngoái entrance into the market. [ 2 ]

Development history[edit]

Wright vertical bốn – cylinder engine

Shaft engines[edit]

Reciprocating ( piston ) engines[edit]

In-line engine[edit]

In this entry, for clarity, the term ” inline engine ” refers only lớn engines with a single row of cylinders, as used in automotive language, but in aviation terms, the phrase ” inline engine ” also covers V-type & opposed engines ( as described below ), và is not limited bự engines with a single row of cylinders. This is typically phệ differentiate them from radial engines. A straight engine typically has an even number of cylinders, but there are instances of three – và five-cylinder engines. The greatest advantage of an inline engine is that it allows the aircraft Khủng be designed with a low frontal area béo minimize drag. If the engine crankshaft is located above the cylinders, it is called an inverted inline engine : this allows the propeller mập be mounted high up Khủng increase ground clearance, enabling shorter landing gear. The disadvantages of an inline engine include a poor power-to-weight ratio, because the crankcase và crankshaft are long & thus heavy. An in-line engine may be either air-cooled or liquid-cooled, but liquid-cooling is more common because it is difficult béo get enough air-flow phệ cool the rear cylinders directly. Inline engines were common in early aircraft ; one was used in the Wright Flyer, the aircraft that made the first controlled powered flight. However, the inherent disadvantages of the kiến thiết soon became apparent, và the inline kiến thiết was abandoned, becoming a rarity in modern aviation .

For other configurations of aviation inline engine, such as X-engines, U-engines, H-engines, etc., see Inline engine (aeronautics).

V-type engine[edit]

A Rolls-Royce Merlin V-12 EngineCylinders in this engine are arranged in two in-line banks, typically tilted 60 – 90 degrees apart from each other và driving a common crankshaft. The vast majority of V engines are water-cooled. The V thiết kế provides a higher power-to-weight ratio than an inline engine, while still providing a small frontal area. Perhaps the most famous example of this thiết kế is the legendary Rolls-Royce Merlin engine, a 27 – litre ( 1649 in3 ) 60 ° V12 engine used in, among others, the Spitfires that played a major role in the Battle of Britain .

Horizontally opposed engine[edit]

A horizontally opposed engine, also called a flat or boxer engine, has two banks of cylinders on opposite sides of a centrally located crankcase. The engine is either air-cooled or liquid-cooled, but air-cooled versions predominate. Opposed engines are mounted with the crankshaft horizontal in airplanes, but may be mounted with the crankshaft vertical in helicopters. Due bự the cylinder layout, reciprocating forces tend phệ cancel, resulting in a smooth running engine. Opposed-type engines have high power-to-weight ratios because they have a comparatively small, lightweight crankcase. In addition, the compact cylinder arrangement reduces the engine’s frontal area và allows a streamlined installation that minimizes aerodynamic drag. Thes e engines always have an even number of cylinders, since a cylinder on one side of the crankcase “ opposes ” a cylinder on the other side .Opposed, air-cooled four – và six-cylinder piston engines are by far the most common engines used in small general aviation aircraft requiring up Khủng 400 horsepower ( 300 kW ) per engine. Aircraft that require more than 400 horsepower ( 300 kW ) per engine tend béo be powered by turbine engines .

H configuration engine[edit]

An H configuration engine is essentially a pair of horizontally opposed engines placed together, with the two crankshafts geared together .

Radial engine[edit]

This type of engine has one or more rows of cylinders arranged around a centrally located crankcase. Each row generally has an odd number of cylinders bự produce smooth operation. A radial engine has only one crank throw per row và a relatively small crankcase, resulting in a favorable power-to-weight ratio. Because the cylinder arrangement exposes a large amount of the engine’s heat-radiating surfaces phệ the air & tends lớn cancel reciprocating forces, radials tend phệ cool evenly & run smoothly. The lower cylinders, which are under the crankcase, may collect oil when the engine has been stopped for an extended period. If this oil is not cleared from the cylinders prior bự starting the engine, serious damage due lớn hydrostatic lock may occur .Most radial engines have the cylinders arranged evenly around the crankshaft, although some early engines, sometimes called semi-radials or người hâm mộ configuration engines, had an uneven arrangement. The best known engine of this type is the Anzani engine, which was fitted mập the Bleriot XI used for the first flight across the English Channel in 1909. This arrangement had the drawback of needing a heavy counterbalance for the crankshaft, but was used Khủng avoid the spark plugs oiling up .In military aircraft designs, the large frontal area of the engine acted as an extra layer of armor for the pilot. Also air-cooled engines, without vulnerable radiators, are slightly less prone Khủng battle damage, & on occasion would continue running even with one or more cylinders shot away. However, the large frontal area also resulted in an aircraft with an aerodynamically inefficient increased frontal area .

Rotary engine[edit]

Le Rhone 9C rotary aircraft engineRotary engines have the cylinders in a circle around the crankcase, as in a radial engine, ( see above ), but the crankshaft is fixed mập the airframe và the propeller is fixed Khủng the engine case, so sánh that the crankcase & cylinders rotate. The advantage of this arrangement is that a satisfactory flow of cooling air is maintained even at low airspeeds, retaining the weight advantage và simplicity of a conventional air-cooled engine without one of their major drawbacks. The first practical rotary engine was the Gnome Omega designed by the Seguin brothers & first flown in 1909. Its relative reliability & good power béo weight ratio changed aviation dramatically. [ 12 ] Before the first World War most tốc độ records were gained using Gnome-engined aircraft, & in the early years of the war rotary engines were dominant in aircraft types for which tốc độ và agility were paramount. To increase power, engines with two rows of cylinders were built .However, the gyroscopic effects of the heavy rotating engine produced handling problems in aircraft và the engines also consumed large amounts of oil since they used total loss lubrication, the oil being mixed with the fuel & ejected with the exhaust gases. Castor oil was used for lubrication, since it is not soluble in petrol, & the resultant fumes were nauseating mập the pilots. Engine designers had always been aware of the many limitations of the rotary engine so sánh when the static phong cách engines became more reliable và gave better specific weights & fuel consumption, the days of the rotary engine were numbered .

Wankel engine[edit]

The Wankel is a type of rotary engine. The Wankel engine is about one half the weight và kích cỡ of a traditional four-stroke cycle piston engine of equal power output, & much lower in complexity. In an aircraft application, the power-to-weight ratio is very important, making the Wankel engine a good choice. Because the engine is typically constructed with an aluminium housing & a steel rotor, và aluminium expands more than steel when heated, a Wankel engine does not seize when overheated, unlike a piston engine. This is an important safety factor for aeronautical use. Considerable development of these designs started after World War II, but at the thời gian the aircraft industry favored the use of turbine engines. It was believed that turbojet or turboprop engines could power all aircraft, from the largest bự smallest designs. The Wankel engine did not find many applications in aircraft, but was used by Mazda in a popular line of sports cars. The French company Citroën had developed Wankel powered RE-2 [ fr ] helicopter in 1970 ‘ s. [ 13 ]In modern times the Wankel engine has been used in motor gliders where the compactness, light weight, và smoothness are crucially important. [ 14 ]The now-defunct Staverton-based firm MidWest designed và produced single – và twin-rotor aero engines, the MidWest AE series. Thes e engines were developed from the motor in the Norton Classic motorcycle. The twin-rotor phiên bản was fitted into ARV Super2s và the Rutan Quickie. The single-rotor engine was put into a Chevvron motor glider & into the Schleicher ASH motor-gliders. After the demise of MidWest, all rights were sold lớn Diamond of Austria, who have since developed a MkII phiên bản of the engine .

As a cost-effective alternative to certified aircraft engines some Wankel engines, removed from automobiles and converted to aviation use, have been fitted in homebuilt experimental aircraft. Mazda units with outputs ranging from 100 horsepower (75 kW) to 300 horsepower (220 kW) can be a fraction of the cost of traditional engines. Such conversions first took place in the early 1970s;[citation needed] and as of 10 December 2006 the National Transportation Safety Board has only seven reports of incidents involving aircraft with Mazda engines, and none of these is of a failure due to design or manufacturing flaws.

Combustion cycles[edit]

The most common combustion cycle for aero engines is the four-stroke with spark ignition. Two-stroke spark ignition has also been used for small engines, while the compression-ignition diesel engine is seldom used .Starting in the 1930 s attempts were made mập produce a practical aircraft diesel engine. In general, Diesel engines are more reliable & much better suited phệ running for long periods of giây phút at medium power settings. The lightweight alloys of the 1930 s were not up béo the task of handling the much higher compression ratios of diesel engines, so sánh they generally had poor power-to-weight ratios và were uncommon for that reason, although the Clerget 14F Diesel radial engine ( 1939 ) has the same power mập weight ratio as a gasoline radial. Improvements in Diesel công nghệ in automobiles ( leading mập much better power-weight ratios ), the Diesel’s much better fuel efficiency & the high relative taxation of AVGAS compared bự Jet A1 in Europe have all seen a revival of interest in the use of diesels for aircraft. Thielert Aircraft Engines converted Mercedes Diesel automotive engines, certified them for aircraft use, và became an OEM provider phệ Diamond Aviation for their light twin. Financial problems have plagued Thielert, so sánh Diamond’s affiliate — Austro Engine — developed the hot nhất AE300 turbodiesel, also based on a Mercedes engine. [ 15 ] Competing mới nhất Diesel engines may bring fuel efficiency và lead-free emissions mập small aircraft, representing the biggest change in light aircraft engines in decades .

Power nguồn turbines[edit]


Cutaway view of a Garrett TPE-331 turboprop engine showing the gearbox at the front of the engineWhile military fighters require very high speeds, many civil airplanes bởi vì not. Yet, civil aircraft designers wanted bự benefit from the high power và low maintenance that a gas turbine engine offered. Thus was born the idea phệ mate a turbine engine bự a traditional propeller. Because gas turbines optimally spin at high tốc độ, a turboprop features a gearbox mập lower the tốc độ of the shaft so sánh that the propeller tips don’t reach supersonic speeds. Often the turbines that drive the propeller are separate from the rest of the rotating components so sánh that they can rotate at their own best tốc độ ( referred béo as a free-turbine engine ). A turboprop is very efficient when operated within the realm of cruise speeds it was designed for, which is typically 200 mập 400 mph ( 320 Khủng 640 km / tiếng ) .


Turboshaft engines are used primarily for helicopters và auxiliary power units. A turboshaft engine is similar bự a turboprop in principle, but in a turboprop the propeller is supported by the engine và the engine is bolted Khủng the airframe : in a turboshaft, the engine does not provide any direct physical tư vấn lớn the helicopter’s rotors. The rotor is connected béo a transmission which is bolted Khủng the airframe, & the turboshaft engine drives the transmission. The distinction is seen by some as slim, as in some cases aircraft companies make both turboprop & turboshaft engines based on the same thiết kế .

Electric power[edit]

A number of electrically powered aircraft, such as the QinetiQ Zephyr, have been designed since the 1960 s. [ 16 ] [ 17 ] Some are used as military drones. [ 18 ] In France in late 2007, a conventional light aircraft powered by an 18 kW electric motor using lithium polymer batteries was flown, covering more than 50 kilometers ( 31 ngươi ), the first electric airplane bự receive a certificate of airworthiness. [ 16 ]On 18 May 2020, the Pipistrel E-811 was the first electric aircraft engine bự be awarded a type certificate by EASA for use in general aviation. The E-811 powers the Pipistrel Velis Electro. [ 19 ] [ 11 ]Limited experiments with solar electric propulsion have been performed, notably the manned Solar Challenger & Solar Impulse và the unmanned NASA Pathfinder aircraft .Many big companies, such as Siemens, are developing high performance electric engines for aircraft use, also, SAE shows mới nhất developments in elements as pure Copper core electric motors with a better efficiency. A hybrid system as emergency back-up & for added power in take-off is offered for marketing by Axter Aerospace, Madrid, Spain. [ đôi mươi ]Small multicopter UAVs are almost always powered by electric motors .

Reaction engines[edit]

Reaction engines generate the thrust phệ propel an aircraft by ejecting the exhaust gases at high velocity from the engine, the resultant reaction of forces driving the aircraft forwards. The most common reaction propulsion engines flown are turbojets, turbofans và rockets. Other types such as pulsejets, ramjets, scramjets & pulse detonation engines have also flown. In jet engines the oxygen necessary for fuel combustion comes from the air, while rockets carry oxygen in some size as part of the fuel load, permitting their use in space .

Jet turbines[edit]


A turbojet is a type of gas turbine engine that was originally developed for military fighters during World War II. A turbojet is the simplest of all aircraft gas turbines. It consists of a compressor bự draw air in & compress it, a combustion section where fuel is added và ignited, one or more turbines that extract power from the expanding exhaust gases lớn drive the compressor, & an exhaust nozzle that accelerates the exhaust gases out the back of the engine bự create thrust. When turbojets were introduced, the top tốc độ of fighter aircraft equipped with them was at least 100 miles per hour faster than competing piston-driven aircraft. In the years after the war, the drawbacks of the turbojet gradually became apparent. Below about Mach 2, turbojets are very fuel inefficient và create tremendous amounts of noise. Early designs also respond very slowly mập power changes, a fact that killed many experienced pilots when they attempted the transition bự jets. Thes e drawbacks eventually led mập the downfall of the pure turbojet, & only a handful of types are still in production. The last airliner that used turbojets was the Concorde, whose Mach 2 airspeed permitted the engine phệ be highly efficient .


A cutaway of a CFM56-3 turbofan engine

A turbofan engine is much the same as a turbojet, but with an enlarged fan at the front that provides thrust in much the same way as a ducted propeller, resulting in improved fuel efficiency. Though the fan creates thrust like a propeller, the surrounding duct frees it from many of the restrictions that limit propeller performance. This operation is a more efficient way to provide thrust than simply using the jet nozzle alone, and turbofans are more efficient than propellers in the transsonic range of aircraft speeds and can operate in the supersonic realm. A turbofan typically has extra turbine stages to turn the fan. Turbofans were among the first engines to use multiple spools—concentric shafts that are free to rotate at their own speed—to let the engine react more quickly to changing power requirements. Turbofans are coarsely split into low-bypass and high-bypass categories. Bypass air flows through the fan, but around the jet core, not mixing with fuel and burning. The ratio of this air to the amount of air flowing through the engine core is the bypass ratio. Low-bypass engines are preferred for military applications such as fighters due to high thrust-to-weight ratio, while high-bypass engines are preferred for civil use for good fuel efficiency and low noise. High-bypass turbofans are usually most efficient when the aircraft is traveling at 500 to 550 miles per hour (800 to 890 kilometres per hour), the cruise speed of most large airliners. Low-bypass turbofans can reach supersonic speeds, though normally only when fitted with afterburners.

Pulse jets[edit]

Pulse jets are mechanically simple devices that — in a repeating cycle — draw air through a no-return valve at the front of the engine into a combustion chamber & ignite it. The combustion forces the exhaust gases out the back of the engine. It produces power as a series of pulses rather than as a steady output, hence the name. The only application of this type of engine was the German unmanned V1 flying bomb of World War II. Though the same engines were also used experimentally for ersatz fighter aircraft, the extremely loud noise generated by the engines caused mechanical damage lớn the airframe that was sufficient lớn make the idea unworkable .


A few aircraft have used rocket engines for main thrust or attitude control, notably the Bell X-1 & North American X-15. Rocket engines are not used for most aircraft as the energy và propellant efficiency is very poor, but have been employed for short bursts of tốc độ và takeoff. Where fuel / propellant efficiency is of lesser concern, rocket engines can be useful because they produce very large amounts of thrust và weigh very little .

Precooled jet engines[edit]

For very high supersonic / low hypersonic flight speeds, inserting a cooling system into the air duct of a hydrogen jet engine permits greater fuel injection at high tốc độ & obviates the need for the duct bự be made of refractory or actively cooled materials. This greatly improves the thrust / weight ratio of the engine at high tốc độ .It is thought that this kiến thiết of engine could permit sufficient performance for antipodal flight at Mach 5, or even permit a single stage béo orbit vehicle béo be practical. The hybrid air-breathing SABRE rocket engine is a pre-cooled engine under development .

Piston-turbofan hybrid[edit]

At the April 2018 ILA Berlin Air Show, Munich – based research institute de : Bauhaus Luftfahrt presented a high-efficiency composite cycle engine for 2050, combining a geared turbofan with a piston engine core. The 2.87 m diameter, 16 – blade người hâm mộ gives a 33.7 ultra-high bypass ratio, driven by a geared low-pressure turbine but the high-pressure compressor drive comes from a piston-engine with two 10 piston banks without a high-pressure turbine, increasing efficiency with non-stationary isochoric – isobaric combustion for higher peak pressures & temperatures. The 11,200 lb ( 49.7 kN ) engine could power a 50 – seat regional jet. [ 21 ]Its cruise TSFC would be 11.5 g / kN / s ( 0.406 lb / lbf / hr ) for an overall engine efficiency of 48.2 %, for a burner temperature of 1,700 K ( 1,430 °C ), an overall pressure ratio of 38 & a peak pressure of 30 MPa ( 300 bar ). [ 22 ] Although engine weight increases by 30 %, aircraft fuel consumption is reduced by 15 %. [ 23 ] Sponsored by the European Commission under Framework 7 project LEMCOTEC, Bauhaus Luftfahrt, MTU Aero Engines & GKN Aerospace presented the concept in năm ngoái, raising the overall engine pressure ratio bự end 100 for a 15.2 % fuel burn reduction compared phệ 2025 engines. [ 24 ]

Engine position numbering[edit]

On multi-engine aircraft, engine positions are numbered from left phệ right from the point of view of the pilot looking forward, so sánh for example on a four-engine aircraft such as the Boeing 747, engine No. một is on the left side, farthest from the fuselage, while engine No. tam is on the right side nearest béo the fuselage. [ 25 ]In the case of the twin-engine English Electric Lightning, which has two fuselage-mounted jet engines one above the other, engine No. một is below & Khủng the front of engine No. 2, which is above & behind. [ 26 ]In the Cessna 337 Skymaster, a push-pull twin-engine airplane, engine No. một is the one at the front of the fuselage, while engine No. 2 is aft of the cabin .


Aircraft reciprocating (piston) engines are typically designed to run on aviation gasoline. Avgas has a higher octane rating than automotive gasoline to allow higher compression ratios, power output, and efficiency at higher altitudes. Currently the most common Avgas is 100LL. This refers to the octane rating (100 octane) and the lead content (LL = low lead, relative to the historic levels of lead in pre-regulation Avgas).[citation needed]

Refineries blend Avgas with tetraethyllead ( TEL ) mập achieve these high octane ratings, a practice that governments no longer permit for gasoline intended for road vehicles. The shrinking supply of TEL và the possibility of environmental legislation banning its use have made a tìm kiếm for replacement fuels for general aviation aircraft a priority for pilots ’ organizations. [ 27 ]

Turbine engines and aircraft diesel engines burn various grades of jet fuel. Jet fuel is a relatively less volatile petroleum derivative based on kerosene, but certified to strict aviation standards, with additional additives.[citation needed]

model aircraft typically use nitro engines ( also known as ” glow engines ” due phệ the use of a glow plug ) powered by glow fuel, a mixture of methanol, nitromethane, & lubricant. Electrically powered Mã Sản Phẩm airplanes [ 28 ] và helicopters are also commercially available. Small multicopter UAVs are almost always powered by electricity, [ 29 ] [ 30 ] but larger gasoline-powered designs are under development. [ 31 ] [ 32 ] [ 33 ]

See also[edit]



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