Aircraft engine
Part of a series on |
Aircraft propulsion |
---|
Shaft engines: driving propellers, rotors, ducted fans or propfans |
Reaction engines |
An aircraft engine, often referred to as an aero engine, is the power component of an
Manufacturing industry
In commercial aviation the major Western manufacturers of
The largest manufacturer of turboprop engines for general aviation is Pratt & Whitney.[3] General Electric announced in 2015 entrance into the market.[3]
Development history
- 1848: John Stringfellow made a steam engine for a 10-foot wingspan model aircraft which achieved the first powered flight, albeit with negligible payload.
- 1903: inline engine, mostly of aluminum, for the Wright Flyer(12 horsepower).
- 1903: Manly-Balzer engine sets standards for later radial engines.[4]
- 1906: Léon Levavasseur produces a successful water-cooled V8 engine for aircraft use.
- 1908: ramjet engine.
- 1908: Grande Semaine d'Aviationsetting a world record for endurance of 180 kilometres (110 mi).
- 1910: Coandă-1910, an unsuccessful ducted fan aircraft 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.[5][6][7][8]
- 1914: Auguste Rateau suggests using exhaust-powered compressor – a turbocharger – to improve high-altitude performance;[4] not accepted after the tests[9]
- 1917-18: The Idflieg-numbered R.30/16 example of the Imperial German Luftstreitkräfte's Zeppelin-Staaken R.VI heavy bomber becomes the earliest known supercharger-equipped aircraft to fly, with a Mercedes D.II straight-six engine in the central fuselage driving a Brown-Boveri mechanical supercharger for the R.30/16's four Mercedes D.IVa engines.
- 1918: Sanford Alexander Moss picks up Rateau's idea and creates the first successful turbocharger[4][10]
- 1926: centrifugal supercharger.
- 1930: turbojet engine.
- June 1939: Heinkel He 176 is the first successful aircraft to fly powered solely by a liquid-fueled rocket engine.
- August 1939: Heinkel HeS 3 turbojet propels the pioneering German Heinkel He 178 aircraft.
- 1940: Jendrassik Cs-1, the world's first run of a turboprop engine. It is not put into service.
- 1943 Daimler-Benz DB 670, first turbofan runs
- 1944: Messerschmitt Me 163B Komet, the world's first rocket-propelled combat aircraft deployed.
- 1945: First turboprop-powered aircraft flies, a modified Gloster Meteor with two Rolls-Royce Trent engines.
- 1947: Bell X-1 rocket-propelled aircraft exceeds the speed of sound.
- 1948: 100 shp 782, the first turboshaft engine 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 first ramjet-powered aircraft flight.
- 1950: Rolls-Royce Conway, the world's first production turbofan, enters service.
- 1968: high bypass turbofanenters service delivering greater thrust and much better efficiency.
- 2002: HyShot scramjet flew in dive.
- 2004: NASA X-43, the first scramjet to maintain altitude.
- 2020: EASA. It powers the Pipistrel Velis Electro, the first fully electric EASA type-certified aeroplane.[12]
Shaft engines
Reciprocating (piston) engines
In-line engine
In this section, for clarity, the term "inline engine" refers only to engines with a single row of cylinders, as used in automotive language, but in 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 from radial 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 poor power-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 the Wright 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 as X-engines, U-engines, H-engines, etc., see Inline engine (aeronautics).
V-type 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 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
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
Opposed, air-cooled four- and six-cylinder piston engines are by far the most common engines used in small general aviation aircraft requiring up to 400 horsepower (300 kW) per engine. Aircraft that require more than 400 horsepower (300 kW) per engine tend to be powered by turbine engines.
H configuration engine
An H configuration engine is essentially a pair of horizontally opposed engines placed together, with the two crankshafts geared together.
Radial engine
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 to produce smooth operation. A radial engine has only one crank throw per row and 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 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 to hydrostatic lock may 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 the
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 an
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 the
However, the gyroscopic effects of 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 oil was 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
The
In modern times the Wankel engine has been used in motor gliders where the compactness, light weight, and smoothness are crucially important.[15]
The now-defunct Staverton-based firm MidWest designed and produced single- and twin-rotor aero engines, the MidWest AE series. These engines were developed from the motor in the Norton Classic motorcycle. The twin-rotor version was fitted into ARV Super2s and the Rutan Quickie. The single-rotor engine was put into a Chevvron motor glider and into the Schleicher ASH motor-gliders. After the demise of MidWest, all rights were sold to Diamond of 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 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
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 1930s attempts were made to produce a practical
Power turbines
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 a
Turboshaft
Turboshaft engines are used primarily for helicopters and auxiliary 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 the airframe: 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 the
On 18 May 2020, the
Limited experiments with
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.[21]
Small
Reaction engines
Reaction engines generate the
necessary for fuel combustion comes from the air, while rockets carry oxygen in some form as part of the fuel load, permitting their use in space.Jet turbines
Turbojet
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 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 the Concorde, whose Mach 2 airspeed permitted the engine to be highly efficient.
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 ducted
Advanced technology engine
The term advanced technology engine refers to the modern generation of jet engines.[22] 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
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 unmanned
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
A few aircraft have used rocket engines for main thrust or attitude control, notably the Bell X-1 and North 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
A rocket turbine engine is a combination of two types of propulsion engines: a liquid-propellant rocket and a turbine jet engine. Its power-to-weight ratio is a little higher than a regular jet engine, and works at higher altitudes.[23]
Precooled jet engines
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-breathing SABRE rocket engine is a pre-cooled engine under development.
Piston-turbofan hybrid
At the April 2018
Its cruise
Engine position numbering
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 the Boeing 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.[28]
In the case of the twin-engine English 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.[29]
In the
Fuel
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) 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 for general aviation aircraft a priority for pilots’ organizations.[30]
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]
See also
- Aviation safety
- Engine configuration
- Federal Aviation Regulations
- Hyper engine
- Model engine
- United States military aircraft engine designations
Notes
- ISBN 978-0-525-93254-3.
References
- ISBN 9780850451634.
- ^ "China launches state-owned aircraft engine maker". CCTV America. August 29, 2016.
- ^ a b "GE Pushes Into Turboprop Engines, Taking on Pratt". Wall Street Journal. November 16, 2015.
- ^ ISBN 978-0-203-19211-5.
- ISBN 9780112900139.
- Her Majesty's Stationery Office.
- ^ Winter, Frank H. (December 1980). "Ducted Fan or the World's First Jet Plane? The Coanda claim re-examined". The Aeronautical Journal. 84. Royal Aeronautical Society.
- ISBN 978-973-7729-61-3.
- ISBN 978-1-84603-432-9.
- ^ Powell, Hickman (Jun 1941). "He Harnessed a Tornado..." Popular Science.
- ISBN 978-1-56347-525-2.
- ^ a b Calderwood, Dave (9 July 2020). "Pipistrel offers type certified electric motor". Seager Publishing. FLYER Magazine. Retrieved 18 August 2020.
- ISBN 1-9007-4752-9.
- ISBN 978-2-907051-17-0.
- ^ "ASH 26 E Information". DE: Alexander Schleicher. Archived from the original on 2006-10-08. Retrieved 2006-11-24.
- ^ "Diamond Twins Reborn". Flying Mag. Archived from the original on 2014-06-18. Retrieved 2010-06-14.
- ^ a b Worldwide première: first aircraft flight with electrical engine, Association pour la Promotion des Aéronefs à Motorisation Électrique, December 23, 2007, archived from the original on 2008-01-10.
- Physorg.com, archived from the originalon 2008-02-23.
- ^ Voyeur, Litemachines, archived from the original on 2009-12-31.
- ^ "TCDS for E811 engine, model 268MVLC" (PDF). European Union Aviation Safety Agency. 18 May 2020. Retrieved 18 August 2020.
- ^ Axter Aerospace
- ISBN 9780850451634.
- ^ "Analysis of the effect of factors on the efficiency of liquid rocket turbine" by Zu, Guojun; Zhang, Yuanjun Journal of Propulsion Technology no. 6, p. 38-43, 58.[1]
- ^ David Kaminski-Morrow (24 April 2018). "Hybrid geared-fan and piston concept could slash fuel-burn". Flightglobal.
- ^ "Composite Cycle Engine concept technical data sheet" (PDF). Bauhaus Luftfahrt.
- ^ "The composite cycle engine concept". Bauhaus Luftfahrt.
- ISBN 978-1-62410-321-6.
- ^ National Business Aircraft Association (1952). Skyways for business. Vol. 11. Henry Publications. p. 52.
- ^ "English Electric Lightning F53 (53-671) – Power Plants". Gatwick Aviation Museum. Archived from the original on 12 June 2018. Retrieved 9 June 2018.
- ^ "EAA'S Earl Lawrence Elected Secretary of International Aviation Fuel Committee" (Press release). Archived from the original on March 3, 2013.
- ^ "Electric Airplanes - RTF". www.nitroplanes.com.
- ^ "Amazon.com: Photography Drones Store: Buying Guide: Electronics". Amazon.
- ^ "RC Quadcopters". www.nitroplanes.com.
- ^ "Yeair! hybrid gasoline/electric quadcopter boasts impressive numbers". www.gizmag.com. 27 May 2015.
- ^ "Goliath – A Gas Powered Quadcopter". hackaday.io.
- ^ "Heavy Lifting Quadcopter Lifts 50 Pound Loads. It's a Gas Powered HULK (HLQ) – Industry Tap". www.industrytap.com. 2013-03-11.
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 1954 Flight article by Bill Gunston
- "Engine Directory". Flight International. 24 September 1997.