Aircraft engine

"Aero-engine" redirects here. For the use of aircraft engines in cars, seeAero-engined car.

ARolls-Royce Merlininstalled in a preservedAvro York

Anaircraft engine,often referred to as anaero engine,is the power component of anaircraftpropulsion system.Aircraft using power components are referred to aspowered flight.Most aircraft engines are eitherpiston enginesorgas turbines,although a few have beenrocket poweredand in recent years many smallUAVshave usedelectric motors.

Manufacturing industry

See also:List of aircraft engines

In commercial aviation the major Western manufacturers ofturbofanengines arePratt & Whitney(a subsidiary ofRaytheon Technologies),General Electric,Rolls-Royce,andCFM International(a joint venture ofSafran Aircraft Enginesand General Electric). Russian manufacturers include theUnited Engine Corporation,AviadvigatelandKlimov.Aeroengine Corporation of Chinawas formed in 2016 with the merger of several smaller companies.

The largest manufacturer ofturbopropengines forgeneral aviationis Pratt & Whitney.General Electric announced in 2015 entrance into the market.

Development history

Wright vertical 4-cylinder engine

See also:Timeline of jet power

• 1848:John Stringfellowmade a steam engine for a 10-foot wingspan model aircraft which achieved the first powered flight, albeit with negligible payload.
• 1903:Charlie Taylorbuilt aninline engine,mostly of aluminum, for theWright Flyer(12 horsepower).
• 1903:Manly-Balzer enginesets standards for laterradial engines.
• 1906:Léon Levavasseurproduces a successful water-cooledV8 enginefor aircraft use.
• 1908:René Lorinpatents a design for theramjet engine.
• 1908:Louis Seguindesigned theGnome Omega,the world's firstrotary engineto be produced in quantity. In 1909 a Gnome poweredFarman IIIaircraft won the prize for the greatest non-stop distance flown at the ReimsGrande Semaine d'Aviationsetting a world record for endurance of 180 kilometres (110 mi).
• 1910:Coandă-1910,an unsuccessfulducted fanaircraft exhibited at Paris Aero Salon, powered by a piston engine. The aircraft never flew, but a patent was filed for routing exhaust gases into the duct to augment thrust.
• 1914:Auguste Rateausuggests using exhaust-powered compressor – aturbocharger– to improve high-altitude performance;not accepted after the tests
• 1915: TheMercedes D.VI- an eighteen-cylinder liquid-cooledW-18 typeaircraft engine - (517 hp/380 kW) was the most powerful engine during WW1.
• 1917-18: TheIdflieg-numbered R.30/16 example of theImperial GermanLuftstreitkräfte'sZeppelin-Staaken R.VIheavy bomber becomes the earliest known supercharger-equipped aircraft to fly, with aMercedes D.IIstraight-six engine in the central fuselage driving a Brown-Boveri mechanical supercharger for the R.30/16's fourMercedes D.IVaengines.
• 1918:Sanford Alexander Mosspicks up Rateau's idea and creates the first successful turbocharger
• 1926:Armstrong Siddeley JaguarIV (S), the first series-produced supercharged engine for aircraft use;two-row radial with a gear-drivencentrifugal supercharger.
• 1930:Frank Whittlesubmitted his first patent for aturbojet engine.
• June 1939:Heinkel He 176is the first successful aircraft to fly powered solely by a liquid-fueled rocket engine.
• August 1939:Heinkel HeS 3turbojet propels the pioneering GermanHeinkel He 178aircraft.
• 1940:Jendrassik Cs-1,the world's first run of aturbopropengine. It is not put into service.
• 1943Daimler-Benz DB 670,first turbofan runs
• 1944:Messerschmitt Me 163BKomet,the world's first rocket-propelled combat aircraft deployed.
• 1945: First turboprop-powered aircraft flies, a modifiedGloster Meteorwith twoRolls-Royce Trentengines.
• 1947:Bell X-1rocket-propelled aircraft exceeds the speed of sound.
• 1948: 100 shp 782, the firstturboshaftengine to be applied to aircraft use; in 1950 used to develop the larger 280 shp (210 kW)Turbomeca Artouste.
• 1949:Leduc 010,the world's firstramjet-powered aircraft flight.
• 1950:Rolls-Royce Conway,the world's first productionturbofan,enters service.
• 1968:General Electric TF39high bypass turbofanenters service delivering greater thrust and much better efficiency.
• 2002:HyShotscramjetflew in dive.
• 2004:NASA X-43,the first scramjet to maintain altitude.
• 2020:Pipistrel E-811is the first electric aircraft engine to be awarded a type certificate byEASA.It powers thePipistrel Velis Electro,the first fully electric EASA type-certified aeroplane.

Shaft engines

Reciprocating (piston) engines

Main article:reciprocating engine

In-line engine

Main article:Straight engine

Ranger L-440 air-cooled, six-cylinder, inverted, in-line engine used inFairchild PT-19

In this section, for clarity, the term "inline engine" refers only to engines with a single row of cylinders, as used in automotive language, butin aviation terms, the phrase "inline engine" also covers V-type and opposed engines(as described below), and is not limited to engines with a single row of cylinders. This is typically to differentiate them fromradial engines.

A straight engine typically has an even number of cylinders, but there are instances of three- and five-cylinder engines. The greatest advantage of an inline engine is that it allows the aircraft to be designed with a low frontal area to minimize drag. If the engine crankshaft is located above the cylinders, it is called an inverted inline engine: this allows the propeller to be mounted high up to increase ground clearance, enabling shorter landing gear. The disadvantages of an inline engine include a poorpower-to-weight ratio,because the crankcase and crankshaft are long and thus heavy. An in-line engine may be either air-cooled or liquid-cooled, but liquid-cooling is more common because it is difficult to get enough air-flow to cool the rear cylinders directly.

Inline engines were common in early aircraft; one was used in theWright Flyer,the aircraft that made the first controlled powered flight. However, the inherent disadvantages of the design soon became apparent, and the inline design was abandoned, becoming a rarity in modern aviation.

For other configurations of aviation inline engine, such asX-engines,U-engines,H-engines,etc., seeInline engine (aeronautics).

V-type engine

A Rolls-Royce Merlin V-12 Engine

Main article:V engine

Cylinders in this engine are arranged in two in-line banks, typically tilted 60–90 degrees apart from each other and driving a common crankshaft. The vast majority of V engines are water-cooled. The V design 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 design is the legendaryRolls-Royce Merlinengine, a 27-litre (1649 in³) 60° V12 engine used in, among others, theSpitfiresthat played a major role in theBattle of Britain.

Horizontally opposed engine

Main article:Flat engine

AULPower UL350iS horizontally opposed air-cooled aero engine

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 inairplanes,but may be mounted with the crankshaft vertical inhelicopters.Due to the cylinder layout, reciprocating forces tend to 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 and allows a streamlined installation that minimizes aerodynamic drag. These 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- and six-cylinder piston engines are by far the most common engines used in smallgeneral aviationaircraft requiring up to 400 horsepower (300 kW) per engine. Aircraft that require more than 400 horsepower (300 kW) per engine tend to be powered byturbine engines.

H configuration engine

Main article:H engine

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

Radial engine

APratt & Whitney R-2800engine

Main article:Radial engine

This type of engine has one or more rows of cylinders arranged around a centrally locatedcrankcase.Each row generally has an odd number of cylinders to produce smooth operation. A radial engine has only onecrank throwper row and a relatively small crankcase, resulting in a favorablepower-to-weight ratio.Because the cylinder arrangement exposes a large amount of the engine's heat-radiating surfaces to the air and tends to cancel reciprocating forces, radials tend to cool evenly and 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 to starting the engine, serious damage due tohydrostatic lockmay occur.

Most radial engines have the cylinders arranged evenly around the crankshaft, although some early engines, sometimes called semi-radials or fan configuration engines, had an uneven arrangement. The best known engine of this type is the Anzani engine, which was fitted to theBleriot XIused for the first flight across theEnglish Channelin 1909. This arrangement had the drawback of needing a heavy counterbalance for the crankshaft, but was used to avoid thespark plugsoiling 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 to battle damage, and on occasion would continue running even with one or more cylinders shot away. However, the large frontal area also resulted in an aircraft with anaerodynamically inefficientincreased frontal area.

Rotary engine

Le Rhone 9C rotary aircraft engine

Main article:Rotary engine

Rotary engines have the cylinders in a circle around the crankcase, as in a radial engine, (see above), but the crankshaft is fixed to the airframe and the propeller is fixed to the engine case, so that the crankcase and 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 and simplicity of a conventional air-cooled engine without one of their major drawbacks. The first practical rotary engine was theGnome Omegadesigned by the Seguin brothers and first flown in 1909. Its relative reliability and good power to weight ratio changed aviation dramatically.Before thefirst World Warmost speed records were gained using Gnome-engined aircraft, and in the early years of the war rotary engines were dominant in aircraft types for which speed and agility were paramount. To increase power, engines with two rows of cylinders were built.

However, thegyroscopic effectsof the heavy rotating engine produced handling problems in aircraft and the engines also consumed large amounts of oil since they used total loss lubrication, the oil being mixed with the fuel and ejected with the exhaust gases.Castor oilwas used for lubrication, since it is not soluble in petrol, and the resultant fumes were nauseating to the pilots. Engine designers had always been aware of the many limitations of the rotary engine so when the static style engines became more reliable and gave better specific weights and fuel consumption, the days of the rotary engine were numbered.

Wankel engine

Main article:Wankel engine

Powerplant from aSchleicher ASH 26eself-launchingmotor glider,removed from the glider and mounted on a test stand for maintenance at theAlexander Schleicher GmbH & CoinPoppenhausen,Germany.Counter-clockwise from top left: propeller hub, mast with belt guide, radiator, Wankel engine, muffler shroud.

TheWankelis a type of rotary engine. TheWankel engineis about one half the weight and size of a traditionalfour-stroke cyclepiston engineof equal power output, and 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 and a steel rotor, and 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 afterWorld War II,but at the time the aircraft industry favored the use ofturbineengines. It was believed thatturbojetorturbopropengines could power all aircraft, from the largest to smallest designs. The Wankel engine did not find many applications in aircraft, but was used byMazdain a popular line ofsports cars.The French companyCitroënhad developed Wankel poweredRE-2helicopterin 1970's.

In modern times the Wankel engine has been used inmotor gliderswhere the compactness, light weight, and smoothness are crucially important.

The now-defunctStaverton-basedfirm MidWest designed and produced single- and twin-rotor aero engines, theMidWest AE series.These engines were developed from the motor in theNorton Classicmotorcycle.The twin-rotor version was fitted intoARV Super2sand theRutan Quickie.The single-rotor engine was put into aChevvron motor gliderand into theSchleicher ASHmotor-gliders. After the demise of MidWest, all rights were sold toDiamondof Austria, who have since developed a MkII version 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 homebuiltexperimental 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;and as of 10 December 2006 theNational Transportation Safety Boardhas 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

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-ignitiondiesel engineis seldom used.

Starting in the 1930s attempts were made to produce a practicalaircraft diesel engine.In general, Diesel engines are more reliable and much better suited to running for long periods of time at medium power settings. The lightweight alloys of the 1930s were not up to the task of handling the much highercompression ratiosof diesel engines, so they generally had poor power-to-weight ratios and were uncommon for that reason, although the Clerget 14F Diesel radial engine (1939) has the same power to weight ratio as a gasoline radial. Improvements in Diesel technology in automobiles (leading to much better power-weight ratios), the Diesel's much better fuel efficiency and the high relative taxation of AVGAS compared to Jet A1 in Europe have all seen a revival of interest in the use of diesels for aircraft.ThielertAircraft Engines converted Mercedes Diesel automotive engines, certified them for aircraft use, and became an OEM provider to Diamond Aviation for their light twin. Financial problems have plagued Thielert, so Diamond's affiliate — Austro Engine — developed the newAE300 turbodiesel,also based on a Mercedes engine.Competing new Diesel engines may bring fuel efficiency and lead-free emissions to small aircraft, representing the biggest change in light aircraft engines in decades.

Power turbines

Turboprop

Cutaway view of aGarrett TPE-331turboprop engine showing the gearbox at the front of the engine

Main article:Turboprop

While military fighters require very high speeds, many civil airplanes do not. Yet, civil aircraft designers wanted to benefit from the high power and low maintenance that agas turbineengine offered. Thus was born the idea to mate a turbine engine to a traditional propeller. Because gas turbines optimally spin at high speed, a turboprop features agearboxto lower the speed of the shaft so 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 that they can rotate at their own best speed (referred to 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 to 400 mph (320 to 640 km/h).

Turboshaft

AnAllison Model 250turboshaft engine common to many types of helicopters

Main article:Turboshaft

Turboshaft engines are used primarily forhelicoptersandauxiliary power units.A turboshaft engine is similar to a turboprop in principle, but in a turboprop the propeller is supported by the engine and the engine is bolted to theairframe:in a turboshaft, the engine does not provide any direct physical support to the helicopter's rotors. The rotor is connected to a transmission which is bolted to the airframe, and the turboshaft engine drives the transmission. The distinction is seen by some as slim, as in some cases aircraft companies make both turboprop and turboshaft engines based on the same design.

Electric power

A number of electrically powered aircraft, such as theQinetiQ Zephyr,have been designed since the 1960s.Some are used as militarydrones.InFrancein 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 mi), the first electric airplane to receive acertificate of airworthiness.

On 18 May 2020, thePipistrel E-811was the first electric aircraft engine to be awarded atype certificatebyEASAfor use ingeneral aviation.The E-811 powers thePipistrel Velis Electro.

Limited experiments withsolar electricpropulsion have been performed, notably the mannedSolar ChallengerandSolar Impulseand the unmannedNASA Pathfinderaircraft.

Many big companies, such as Siemens, are developing high performance electric engines for aircraft use, also, SAE shows new developments in elements as pure Copper core electric motors with a better efficiency. A hybrid system as emergency back-up and for added power in take-off is offered for sale by Axter Aerospace, Madrid, Spain.

SmallmulticopterUAVs are almost always powered by electric motors.

Reaction engines

Main article:Jet engine

Reaction engines generate thethrustto propel an aircraft by ejecting the exhaust gases at high velocity from the engine, the resultantreaction of forcesdriving the aircraft forwards. The most common reaction propulsion engines flown are turbojets, turbofans and rockets. Other types such aspulsejets,ramjets,scramjetsandpulse detonation engineshave also flown. In jet engines theoxygennecessary for fuel combustion comes from the air, while rockets carry anoxidizer(usually oxygen in some form) as part of the fuel load, permitting their use in space.

Jet turbines

Turbojet

AGeneral Electric J85-GE-17A turbojet engine. This cutaway clearly shows the 8 stages ofaxial compressorat the front (left side of the picture), thecombustion chambersin the middle, and the two stages ofturbinesat the rear of the engine.

Main article:Turbojet

A turbojet is a type ofgas turbineengine that was originally developed for militaryfightersduringWorld War II.A turbojet is the simplest of all aircraft gas turbines. It consists of a compressor to draw air in and compress it, a combustion section where fuel is added and ignited, one or more turbines that extract power from the expanding exhaust gases to drive the compressor, and an exhaust nozzle that accelerates the exhaust gases out the back of the engine to create thrust. When turbojets were introduced, the top speed 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 and create tremendous amounts of noise. Early designs also respond very slowly to power changes, a fact that killed many experienced pilots when they attempted the transition to jets. These drawbacks eventually led to the downfall of the pure turbojet, and only a handful of types are still in production. The last airliner that used turbojets was theConcorde,whose Mach 2 airspeed permitted the engine to be highly efficient.

Turbofan

A cutaway of aCFM56-3turbofan engine

Main article:Turbofan

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 ductedpropeller,resulting in improvedfuel 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 thejet nozzlealone, and turbofans are more efficient than propellers in the transsonic range of aircraft speeds and can operate in thesupersonicrealm. A turbofan typically has extra turbine stages to turn the fan. Turbofans were among the first engines to use multiplespools—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 mi xing 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 withafterburners.

Advanced technology engine

Main article:Advanced technology engine

The termadvanced technology enginerefers to the modern generation of jet engines.The principle is that a turbine engine will function more efficiently if the various sets of turbines can revolve at their individual optimum speeds, instead of at the same speed. The true advanced technology engine has a triple spool, meaning that instead of having a single drive shaft, there are three, in order that the three sets of blades may revolve at different speeds. An interim state is a twin-spool engine, allowing only two different speeds for the turbines.

Pulsejets

Main article:Pulsejet

Pulsejets 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 and 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 unmannedV1 flying bombofWorld 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 to the airframe that was sufficient to make the idea unworkable.

Gluhareff Pressure Jet

Main article:Gluhareff Pressure Jet

The Gluhareff Pressure Jet (or tip jet) is a type of jet engine that, like a valveless pulsejet, has no moving parts. Having no moving parts, the engine works by having a coiled pipe in the combustion chamber that superheats the fuel (propane) before being injected into the air-fuel inlet. In the combustion chamber, the fuel/air mixture ignites and burns, creating thrust as it leaves through the exhaust pipe. Induction and compression of the fuel/air mixture is done both by the pressure of propane as it is injected, along with the sound waves created by combustion acting on the intake stacks. It was intended as a power plant for personal helicopters and compact aircraft such as Microlights.

Rocket

AnXLR99

Main article:Rocket engine

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

Rocket turbine engine

Main article:Rocket turbine engine

A rocket turbine engine is a combination of two types of propulsion engines: aliquid-propellant rocketand a turbine jet engine. Itspower-to-weight ratiois a little higher than a regular jet engine, and works at higher altitudes.

Precooled jet engines

Main article:Precooled jet engine

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 speed and obviates the need for the duct to be made of refractory or actively cooled materials. This greatly improves the thrust/weight ratio of the engine at high speed.

It is thought that this design of engine could permit sufficient performance for antipodal flight at Mach 5, or even permit a single stage to orbit vehicle to be practical. The hybrid air-breathingSABRE rocket engineis a pre-cooled engine under development.

Piston-turbofan hybrid

At the April 2018ILA Berlin Air Show,Munich-based research institutede:Bauhaus Luftfahrtpresented a high-efficiency composite cycle engine for 2050, combining ageared turbofanwith apiston enginecore. The 2.87 m diameter, 16-blade fan gives a 33.7 ultra-highbypass 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-stationaryisochoric-isobariccombustion for higher peak pressures and temperatures. The 11,200 lb (49.7 kN) engine could power a 50-seatregional jet.

Its cruiseTSFCwould be 11.5 g/kN/s (0.406 lb/lbf/hr) for an overallengine efficiencyof 48.2%, for a burner temperature of 1,700 K (1,430 °C), anoverall pressure ratioof 38 and a peak pressure of 30 MPa (300 bar). Although engine weight increases by 30%,aircraft fuel consumptionis reduced by 15%. Sponsored by theEuropean Commissionunder Framework 7 projectLEMCOTEC,Bauhaus Luftfahrt,MTU Aero EnginesandGKN Aerospacepresented the concept in 2015, raising the overall engine pressure ratio to over 100 for a 15.2% fuel burn reduction compared to 2025 engines.

Engine position numbering

Thethrust leversof a three-engineBoeing 727,each one bearing the respective engine number

On multi-engine aircraft, engine positions are numbered from left to right from the point of view of the pilot looking forward, so for example on a four-engine aircraft such as theBoeing 747,engine No. 1 is on the left side, farthest from the fuselage, while engine No. 3 is on the right side nearest to the fuselage.

In the case of the twin-engineEnglish Electric Lightning,which has two fuselage-mounted jet engines one above the other, engine No. 1 is below and to the front of engine No. 2, which is above and behind.

In theCessna 337 Skymaster,apush-pulltwin-engine airplane, engine No. 1 is the one at the front of the fuselage, while engine No. 2 is aft of the cabin.

Fuel

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

Refineries blend Avgas withtetraethyllead(TEL) to achieve these high octane ratings, a practice that governments no longer permit for gasoline intended for road vehicles. The shrinking supply of TEL and the possibility of environmental legislation banning its use have made a search for replacement fuels forgeneral aviationaircraft a priority for pilots’ organizations.

Turbine engines andaircraft diesel enginesburn various grades ofjet fuel.Jet fuel is a relatively less volatilepetroleumderivative based onkerosene,but certified to strict aviation standards, with additional additives.

Model aircrafttypically usenitro engines(also known as "glow engines" due to the use of aglow plug) powered byglow fuel,a mixture ofmethanol,nitromethane,and lubricant. Electrically powered model airplanesand helicopters are also commercially available. SmallmulticopterUAVsare almost always powered by electricity,but larger gasoline-powered designs are under development.

See also

• Aviation safety
• Engine configuration
• Federal Aviation Regulations
• Hyper engine
• Model engine
• United States military aircraft engine designations

External links

• Aircraft Engines and Aircraft Engine Theory (includes links to diagrams)
• The Aircraft Engine Historical Society
• Jet Engine Specification Database
• Aircraft Engine Efficiency: Comparison of Counter-rotating and Axial Aircraft LP Turbines
• The History of Aircraft Power Plants Briefly Reviewed: From the "7 lb. per h.p" Days to the "1 lb. per h.p" of To-day
• "The Quest for Power"a 1954Flightarticle byBill Gunston
• "Engine Directory".Flight International.24 September 1997.