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Not to be confused with propfan.
Schematic diagram of a high-bypass turbofan engine
Rolls-Royce Trent 1000 turbofan powering a Boeing 787 Dreamliner testflight
Engine Alliance GP7000 turbofan awaiting installation on an Airbus A380 under construction

The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the turbo portion refers to a gas turbine engine which achieves mechanical energy from combustion,[1] and the fan, a ducted fan that uses the mechanical energy from the gas turbine to accelerate air rearwards. Thus, whereas all the air taken in by a turbojet passes through the turbine (through the combustion chamber), in a turbofan some of that air bypasses the turbine. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of those contributing to the thrust. The ratio of the mass-flow of air bypassing the engine core compared to the mass-flow of air passing through the core is referred to as the bypass ratio. The engine produces thrust through a combination of these two portions working in concert; engines that use more jet thrust relative to fan thrust are known as low-bypass turbofans, conversely those that have considerably more fan thrust than jet thrust are known as high-bypass. Most commercial aviation jet engines in use today are of the high-bypass type,[2][3] and most modern military fighter engines are low-bypass.[4][5] Afterburners are not used on high-bypass turbofan engines but may be used on either low-bypass turbofan or turbojet engines.

Most of the air flow through a high-bypass turbofan is low-velocity bypass flow: even when combined with the much higher velocity engine exhaust, the average exhaust velocity is considerably lower than in a pure turbojet. Turbojet engine noise is predominately jet noise from the high exhaust velocity, therefore turbofan engines are significantly quieter than a pure-jet of the same thrust with jet noise no longer the predominant source. Other noise sources are the fan, compressor and turbine.[6] Jet noise is reduced with chevrons, sawtooth patterns on the exhaust nozzles,[7] on the Rolls-Royce Trent 1000 and General Electric GEnx engines used on the Boeing 787.


Modern turbofans have either a large single-stage fan or a smaller fan with several stages. An early configuration combined a low-pressure turbine and fan in a single rear-mounted unit.

Early turbofans[edit]

Rolls-Royce Conway low bypass turbofan from a Boeing 707. The bypass air exits from the fins whilst the exhaust from the core exits from the central nozzle. This fluted jetpipe design is a noise-reducing method devised by Frederick Greatorex at Rolls-Royce
General Electric GEnx-2B turbofan engine from a Boeing 747-8. View into the outer (propelling or "cold") nozzle.

Early turbojet engines were not very fuel-efficient as their overall pressure ratio and turbine inlet temperature were severely limited by the technology available at the time. In 1939-1941 Soviet designer Arkhip Lyulka elaborated the design for the world's first turbofan engine, and acquired a patent for this new invention on April 22, 1941. Although several prototypes were built and ready for testing, Lyulka was in 1941 forced to abandon his research and evacuate to the Urals following the Nazi invasion of the Soviet Union. So the first turbofan to run was apparently the German Daimler-Benz DB 670 (designated as the 109-007 by the RLM) with a first run date of 27 May 1943. Turbomachinery testing, using an electric motor, had started on 1 April 1943.[10] The engine was abandoned later while the war went on and problems could not be solved. The British wartime Metrovick F.2 axial flow jet was given a fan, as the Metrovick F.3 in 1943, to create the first British turbofan.[11]

Improved materials, and the introduction of twin compressors such as in the Bristol Olympus[12] and Pratt & Whitney JT3C engines, increased the overall pressure ratio and thus the thermodynamic efficiency of engines, but they also led to a poor propulsive efficiency, as pure turbojets have a high specific thrust/high velocity exhaust better suited to supersonic flight.


The first General Electric turbofan was the aft-fan CJ805-23 based on the CJ805-3 turbojet. It was followed by the aft-fan General Electric CF700 engine with a 2.0 bypass ratio. This was derived from the General Electric J85/CJ610 turbojet (2,850 lbf or 12,650 N) to power the larger Rockwell Sabreliner 75/80 model aircraft, as well as the Dassault Falcon 20 with about a 50% increase in thrust (4,200 lbf or 18,700 N). The CF700 was the first small turbofan in the world to be certified by the Federal Aviation Administration (FAA). There were at one time over 400 CF700 aircraft in operation around the world, with an experience base of over 10 million service hours. The CF700 turbofan engine was also used to train Moon-bound astronauts in Project Apollo as the powerplant for the Lunar Landing Research Vehicle.

Low-bypass turbofan[edit]



To illustrate one aspect of how a turbofan differs from a turbojet they may be compared, as in a re-engining assessment, at the same airflow (to keep a common intake for example) and the same net thrust (i.e. same specific thrust). A bypass flow can only be added to the turbojet if the turbine inlet temperature is allowed to increase to compensate for the smaller core flow. Improvements in turbine cooling/material technology would allow the use of a higher turbine inlet temperature despite an increase in cooling air temperature which would result from any overall pressure-ratio increase.

The resulting turbofan, with reasonable efficiencies and duct loss for the added components, would probably operate at a higher nozzle pressure ratio than the turbojet, but with a lower exhaust temperature to retain net thrust. Since the temperature rise across the whole engine (intake to nozzle) would be lower, the (dry power) fuel flow would also be reduced, resulting in a better specific fuel consumption (SFC).

Some low-bypass ratio military turbofans (e.g. F404) have variable inlet guide vanes to direct air onto the first fan rotor stage. This improves the fan surge margin (see compressor map).

Afterburning turbofan[edit]

Further information: Afterburner
Pratt & Whitney F119 afterburning turbofan on test



The first production afterburning turbofan engine was the Pratt & Whitney TF30, which initially powered the F-111 Aardvark and F-14 Tomcat. Current low-bypass military turbofans include the Pratt & Whitney F119, the Eurojet EJ200, the General Electric F110, the Klimov RD-33, and the Saturn AL-31, all of which feature a mixed exhaust, afterburner and variable area propelling nozzle.

High-bypass turbofan[edit]

Further information: Bypass ratio
Animation of a 2-spool, high-bypass turbofan.
  1. Low-pressure spool
  2. High-pressure spool
  3. Stationary components
  1. Nacelle
  2. Fan
  3. Low-pressure compressor
  4. High-pressure compressor
  5. Combustion chamber
  6. High-pressure turbine
  7. Low-pressure turbine
  8. Core nozzle
  9. Fan nozzle

The low-specific-thrust/high-bypass-ratio turbofans used in today's civil jetliners (and some military transport aircraft) evolved from the high-specific-thrust/low-bypass-ratio turbofans used in such aircraft back in the 1960s.

Low specific thrust is achieved by replacing the multi-stage fan with a single-stage unit. Unlike some military engines, modern civil turbofans do not have any stationary inlet guide vanes in front of the fan rotor. The fan is scaled to achieve the desired net thrust.


Further improvements in core thermal efficiency can be achieved by raising the overall pressure ratio of the core. Improved blade aerodynamics reduces the number of extra compressor stages required. With multiple compressors (i.e., LPC, IPC, and HPC) dramatic increases in overall pressure ratio have become possible. Variable geometry (i.e., stators) enable high-pressure-ratio compressors to work surge-free at all throttle settings.

Cutaway diagram of the General Electric CF6-6 engine

The first (experimental) high-bypass turbofan engine was built and run on February 13, 1964 by AVCO-Lycoming.[13][14] Shortly after, the General Electric TF39 became the first production model, designed to power the Lockheed C-5 Galaxy military transport aircraft.[9] The civil General Electric CF6 engine used a derived design. Other high-bypass turbofans are the Pratt & Whitney JT9D, the three-shaft Rolls-Royce RB211 and the CFM International CFM56; also the smaller TF34. More recent large high-bypass turbofans include the Pratt & Whitney PW4000, the three-shaft Rolls-Royce Trent, the General Electric GE90/GEnx and the GP7000, produced jointly by GE and P&W.

For reasons of fuel economy, and also of reduced noise, almost all of today's jet airliners are powered by high-bypass turbofans. Although modern combat aircraft tend to use low-bypass ratio turbofans, military transport aircraft (e.g., C-17 ) mainly use high-bypass ratio turbofans (or turboprops) for fuel efficiency.

The lower the specific thrust of a turbofan, the lower the mean jet outlet velocity, which in turn translates into a high thrust lapse rate ( i.e. decreasing thrust with increasing flight speed). See technical discussion below, item 2. Consequently, an engine sized to propel an aircraft at high subsonic flight speed (e.g., Mach 0.83) generate a relatively high thrust at low flight speed, thus enhancing runway performance. Low specific thrust engines tend to have a high bypass ratio, but this is also a function of the temperature of the turbine system.

The turbofans on twin engined airliners are further more powerful to cope with losing one engine during take-off, which reduces the aircraft's net thrust by half. Modern twin engined airliners normally climb very steeply immediately after take-off. If one engine is lost, the climb-out is much shallower, but sufficient to clear obstacles in the flightpath.


Turbofan configurations[edit]


As the design overall pressure ratio of an engine cycle increases, it becomes more difficult to operate at low rpm, without encountering an instability known as compressor surge. This occurs when some of the compressor aerofoils stall (like the wings of an aircraft) causing a violent change in the direction of the airflow. However, compressor stall can be avoided, at low rpm, by progressively:

  1. opening interstage/intercompressor blow-off valves (inefficient), and/or
  2. closing variable stators within the compressor

Most modern American civil turbofans employ a relatively high-pressure-ratio high-pressure (HP) compressor, with many rows of variable stators to control surge margin at low rpm. In the three-spool RB211/Trent the core compression system is split into two, with the IP compressor, which supercharges the HP compressor, being on a different coaxial shaft and driven by a separate (IP) turbine. As the HP compressor has a modest pressure ratio its speed can be reduced surge-free, without employing variable geometry. However, because a shallow IP compressor working line is inevitable, the IPC has one stage of variable geometry on all variants except the -535, which has none.[15]

Single-shaft turbofan[edit]


Aft-fan turbofan[edit]

One of the earliest turbofans was a derivative of the General Electric J79 turbojet, known as the CJ805-23, which featured an integrated aft fan/low-pressure (LP) turbine unit located in the turbojet exhaust jetpipe. Hot gas from the turbojet turbine exhaust expanded through the LP turbine, the fan blades being a radial extension of the turbine blades. This aft-fan configuration was later exploited in the General Electric GE-36 UDF (propfan) demonstrator of the early 80s. One of the problems with the aft fan configuration is hot gas leakage from the LP turbine to the fan.[citation needed]

Basic two-spool[edit]


Boosted two-spool[edit]



Rolls-Royce chose a three-spool configuration for their large civil turbofans (i.e., the RB211 and Trent families), where the intermediate pressure (IP) compressor is mounted on a separate (IP) shaft, running concentrically with the LP and HP shafts, and is driven by a separate IP turbine. The first three-spool engine was the earlier Rolls-Royce RB.203 Trent of 1967.


The Turbo-Union RB199 military turbofan also has a three-spool configuration, as do the military Kuznetsov NK-25 and NK-321.

Geared fan[edit]

Main article: Geared turbofan
Geared turbofan


Military turbofans[edit]

Ducting on a Dassault/Dornier Alpha Jet — At subsonic speeds, the increasing diameter of the inlet duct slows incoming air, causing its static pressure to increase.


High-pressure turbine[edit]

Most civil turbofans use a high-efficiency, 2-stage HP turbine to drive the HP compressor. The CFM56 uses an alternative approach: a single-stage, high-work unit. While this approach is probably less efficient, there are savings on cooling air, weight and cost.

In the RB211 and Trent 3-spool engine series, the HP compressor pressure ratio is modest so only a single HP stage is required. Rather than adding stage/s to the LP turbine to drive the higher pressure ratio IP (intermediate pressure) compressor, Rolls-Royce mounts it on a separate shaft and drives it with an IP turbine.

Because the HP compressor pressure ratio is modest, modern military turbofans tend to use a single-stage HP turbine.

Low-pressure turbine[edit]


Cycle improvements[edit]




According to simple theory, if the ratio of turbine rotor inlet temperature/(HP) compressor delivery temperature is maintained, the HP turbine throat area can be retained. However, this assumes that cycle improvements are obtained, while retaining the datum (HP) compressor exit flow function (non-dimensional flow). In practice, changes to the non-dimensional speed of the (HP) compressor and cooling bleed extraction would probably make this assumption invalid, making some adjustment to HP turbine throat area unavoidable. This means the HP turbine nozzle guide vanes would have to be different from the original. In all probability, the downstream LP turbine nozzle guide vanes would have to be changed anyway.

Thrust growth[edit]


  1. hot route: increase HP turbine rotor inlet temperature
  2. cold route: increase core mass flow



  1. adding T-stages to the LP/IP compression
  2. adding a zero-stage to the HP compression

all of which increase both overall pressure ratio and core airflow.


Changes must also be made to the fan to absorb the extra core power. On a civil engine, jet noise considerations mean that any significant increase in take-off thrust must be accompanied by a corresponding increase in fan mass flow (to maintain a T/O specific thrust of about 30 lbf/lb/s).

Technical discussion[edit]

  1. Specific thrust (net thrust/intake airflow) is an important parameter for turbofans and jet engines in general. Imagine a fan (driven by an appropriately sized electric motor) operating within a pipe, which is connected to a propelling nozzle. It is fairly obvious, the higher the fan pressure ratio (fan discharge pressure/fan inlet pressure), the higher the jet velocity and the corresponding specific thrust. Now imagine we replace this set-up with an equivalent turbofan - same airflow and same fan pressure ratio. Obviously, the core of the turbofan must produce sufficient power to drive the fan via the low-pressure (LP) turbine. If we choose a low (HP) turbine inlet temperature for the gas generator, the core airflow needs to be relatively high to compensate. The corresponding bypass ratio is therefore relatively low. If we raise the turbine inlet temperature, the core airflow can be smaller, thus increasing bypass ratio. Raising turbine inlet temperature tends to increase thermal efficiency and, therefore, improve fuel efficiency.
  2. Naturally, as altitude increases, there is a decrease in air density and, therefore, the net thrust of an engine. There is also a flight speed effect, termed thrust lapse rate. Consider the approximate equation for net thrust again:

  3. Thrust growth on civil turbofans is usually obtained by increasing fan airflow, thus preventing the jet noise becoming too high. However, the larger fan airflow requires more power from the core. This can be achieved by raising the overall pressure ratio (combustor inlet pressure/intake delivery pressure) to induce more airflow into the core and by increasing turbine inlet temperature. Together, these parameters tend to increase core thermal efficiency and improve fuel efficiency.
  7. Because military engines usually have to be able to fly very fast at sea level, the limit on HP compressor delivery temperature is reached at a fairly modest design overall pressure ratio, compared with that of a civil engine. Also the fan pressure ratio is relatively high, to achieve a medium to high specific thrust. Consequently, modern military turbofans usually only have 5 or 6 HP compressor stages and only require a single-stage HP turbine. Low-bypass-ratio military turbofans usually have one LP turbine stage, but higher bypass ratio engines need two stages. In theory, by adding IP compressor stages, a modern military turbofan HP compressor could be used in a civil turbofan derivative, but the core would tend to be too small for high thrust applications.

Engine noise[edit]

Modern commercial aircraft employ high-bypass-ratio (HBPR) engines with separate flow, non-mixing, short-duct exhaust systems. These propulsion systems are known to generate significantly high noise levels due to the high-speed, high-temperature, and high-pressure nature of the exhaust jet, especially during high thrust conditions such as those required for takeoff. The primary source of jet noise is the turbulent mixing of shear layers in the engine’s exhaust. These shear layers contain instabilities that lead to highly turbulent vortices that generate the pressure fluctuations responsible for sound. In order to reduce the noise associated with jet flow, the aerospace industry has focused on developing various technologies to disrupt shear layer turbulence and reduce the overall noise produced.

Turbofan engine noise propagates both upstream the inlet and downstream the primary nozzle and the by-pass duct. The main noise sources are the turbine and the compressor, the jet and the fan. The contribution of each noise source significantly evolved in the last decades:[17] in typical 1960s design the jet was the main source whereas in modern turbofans the fan is the main noise source.

The fan noise is a tonal noise and its signature depends on the fan rotational speed:

  • at low speed, the fan noise is due to the interaction of the blades with the distorted flow injected in the engine; this happens for example during the approach;
  • at high engine ratings, the fan tip is supersonic and this allows intense rotor-locked duct modes to propagate upstream; this noise is known as "buzz saw" and is typical at take-off.[18]

All modern turbofan engines are equipped with acoustic liners to damp the noise generated. These are installed in the nacelle, and they extend as much as possible to cover the largest area. The acoustic performance of the engine can be experimentally evaluated by means of ground tests[19] or in dedicated experimental test rigs.[20]

Chevrons on an Air India Boeing 787 GE GEnx engine.

In the aerospace industry, chevrons are the saw tooth patterns on the trailing edges of some jet engine nozzles[21] that are used for noise reduction. Their principle of operation is that, as hot air from the engine core mixes with cooler air blowing through the engine fan, the shaped edges serve to smooth the mixing, which reduces noise-creating turbulence.[21] Chevrons were developed with the help of NASA.[21][22] Some notable examples of such engines include GEnx and Rolls-Royce Trent 1000.

Recent developments[edit]

Blade technology[edit]






Aerodynamics is a mix of subsonic, transonic and supersonic airflow on a single fan/gas compressor blade in a modern turbofan. The airflow past the blades has to be maintained within close angular limits to keep the air flowing against an increasing pressure. Otherwise the air will come back out of the intake.[24]


A 100 g turbine blade is subjected to 1,700 °C/3100 °F, at 17 bars/250 Psi and a centrifugal force of 40 kN/ 9,000 lbf, well above the point of plastic deformation and even above the melting point. Exotic alloys, sophisticated air cooling schemes and special mechanical design are needed to keep the physical stresses within the strength of the material. Rotating seals must withstand harsh conditions for 10 years, 20,000 missions and rotating at 10–20,000 rpm.[24]


The Full Authority Digital Engine Control needs accurate data for controlling the engine. The critical turbine inlet temperature (TIT) is too harsh an environment, at 1,700 °C and 17 bars, for reliable sensors. During development of a new engine type a relation is established between a more easily measured temperature like Exhaust gas temperature and the TIT. The EGT is then used to make sure the engine doesn't run too hot.[24]


The turbofan engine market is dominated by General Electric, Rolls-Royce plc and Pratt & Whitney, in order of market share. GE and SNECMA of France have a joint venture, CFM International. Pratt & Whitney also have a joint venture, International Aero Engines with Japanese Aero Engine Corporation and MTU of Germany, specializing in engines for the Airbus A320 family. Pratt & Whitney and General Electric have a joint venture, Engine Alliance selling a range of engines for aircraft such as the Airbus A380.

For airliners and cargo aircraft, the in-service fleet in 2016 is 60,000 engines and should grow to 103,000 in 2035 with 86,500 deliveries according to Flight Global. A majority will be medium-thrust engines for narrow-body aircraft with 54,000 deliveries, for a fleet growing from 28,500 to 61,000. High-thrust engines for wide-body aircraft, worth 40–45% of the market by value, will grow from 12,700 engines to over 21,000 with 18,500 deliveries. The regional jet engines below 20,000lb (89kN) fleet will grow from 7,500 to 9,000 and the fleet of turboprops for airliners will increase from 9,400 to 10,200. The manufacturers market share should be led by CFM with 44% followed by Pratt & Whitney with 29% and then Rolls-Royce and General Electric with 10% each.[25]

General Electric[edit]




Pratt & Whitney[edit]


CFM International[edit]


Engine Alliance[edit]

Engine Alliance is a 50/50 joint venture between General Electric and Pratt & Whitney formed in August 1996 to develop, manufacture, sell, and support a family of modern technology aircraft engines for new high-capacity, long-range aircraft.[26] The main application for such an engine, the GP7200, was originally the Boeing 747-500/600X projects, before these were cancelled owing to lack of demand from airlines. Instead, the GP7000 has been re-optimised for use on the Airbus A380 superjumbo. In that market it is competing with the Rolls-Royce Trent 900, the launch engine for the aircraft. The two variants are the GP7270 and the GP7277.

International Aero Engines[edit]

International Aero Engines is a Zürich-registered joint venture between Pratt & Whitney, MTU Aero Engines and Japanese Aero Engine Corporation. The collaboration produced the V2500, the second most successful commercial jet engine program in production today in terms of volume, and the third most successful commercial jet engine program in aviation history.[27]

Williams International[edit]


Honeywell Aerospace[edit]

Honeywell Aerospace is one of the largest manufacturer of aircraft engines and avionics,[28] as well as a producer of auxiliary power units (APUs) and other aviation products. Headquartered in Phoenix, Arizona, it is a division of the Honeywell International conglomerate. Honeywell/ITEC F124 series is used in military jets, such as the Aero L-159 Alca and the Alenia Aermacchi M-346. The Honeywell HTF700 series is used in the Bombardier Challenger 300[29] and the Gulfstream G280.[30] The ALF502 and LF507 turbofans are produced by a partnership between Honeywell and China's state-owned Industrial Development Corporation. The partnership is called the International Turbine Engine Co.[31]


Aviadvigatel is a Russian manufacturer of aircraft engines that succeeded the Soviet Soloviev Design Bureau. The company currently offers[32] several versions of the Aviadvigatel PS-90 engine that powers Ilyushin Il-96-300/400/400T, Tupolev Tu-204, Tu-214 series and the Ilyushin Il-76-MD-90. The company is also developing the new Aviadvigatel PD-14 engine for the new Russian MS-21 airliner.[33]



NPO Saturn[edit]

NPO Saturn is a Russian aircraft engine manufacturer, formed from the mergers of Rybinsk and Lyul'ka-Saturn. Saturn's engines include Lyulka AL-31, Lyulka AL-41, NPO Saturn AL-55 and power many former Eastern Bloc aircraft, such as the Tupolev Tu-154. Saturn holds a 50% stake in the PowerJet joint venture with Snecma.


PowerJet is a 50-50 joint venture between Snecma (Safran) and NPO Saturn, created in July 2004. The company manufactures SaM146, the sole powerplant for the Sukhoi Superjet 100.


Klimov was formed in the early 1930s to produce and improve upon the liquid-cooled Hispano-Suiza 12Y V-12 piston engine for which the USSR had acquired a license. Currently, Klimov is the manufacturer of the Klimov RD-33 turbofan engines.


EuroJet Turbo GmbH is a multi-national consortium, the partner companies of which are Rolls Royce of the United Kingdom, Avio of Italy, ITP of Spain and MTU Aero Engines of Germany. Eurojet GmbH was formed in 1986 to manage the development, production, support, maintenance, support and sales of the EJ200 turbofan engine for the Eurofighter Typhoon.[34]

Chinese turbofans[edit]

Three Chinese corporations build turbofan engines. Some of these are licensed or reverse engineered versions of European and Russian turbofans, and the other are indigenous models, but all are in development phase. Shenyang Aircraft Corporation (manufacturer of Shenyang WS-10), Xi'an Aero-Engine Corporation (manufacturer of Xian WS-15) and Guizhou Aircraft Industry Corporation (manufacturer of Guizhou WS-13) manufacture turbofans.

Japanese turbofans[edit]

Ishikawajima-Harima Heavy Industries is the Japan aircraft engine company. The company manufactures F3 for Kawasaki T-4, XF5-1 for ATD-X, F7 for Kawasaki P-1.

Gas Turbine Research Establishment (GTRE)[edit]

Gas Turbine Research Establishment is owned by DRDO of Government of India. It produced the GTRE GTX-35VS Kaveri turbofan intended to power HAL Tejas and HAL Advanced Medium Combat Aircraft being built by the Aeronautical Development Agency.

Commercial turbofans in production[35]
Model Start Bypass Length Fan Weight Thrust Major applications
GE GE90 1992 8.7–9.9 5.18m–5.40m 3.12–3.25 m 7.56–8.62t 330–510 kN B777
P&W PW4000 1984 4.8–6.4 3.37–4.95m 2.84 m 4.18–7.48t 222–436 kN A300/A310, A330, B747, B767, B777, MD-11
R-R Trent XWB 2010 9.3 5.22 m 3.00 m 7.28 t 330–430 kN A350XWB
R-R Trent 800 1993 5.7–5.79 4.37m 2.79m 5.96–5.98t 411–425 kN B777
EA GP7000 2004 8.7 4.75 m 2.95 m 6.09-6.71 t 311-363 kN A380
R-R Trent 900 2004 8.7 4.55 m 2.95 m 6.18-6.25 t 340-357 kN A380
R-R Trent 1000 2006 10.8–11 4.74 m 2.85 m 5.77 t 265.3-360.4 kN B787
GE GEnx[36] 2006 8.0-9.3 4.31-4.69 m 2.66-2.82 m 5.62-5.82 t 296-339 kN B747-8, B787
R-R Trent 700 1990 4.9 3.91 m 2.47 m 4.79 t 320 kN A330
GE CF6 1971 4.3-5.3 4.00-4.41 m 2.20-2.79 m 3.82-5.08 t 222-298 kN A300/A310, A330, B747, B767, MD-11
R-R Trent 500 1999 8.5 3.91 m 2.47 m 4.72 t 252 kN A340
P&W PW1000G[37] 2008 9.0-12.5 3.40 m 1.42-2.06 m 2.86 t 67-160 kN A320neo, CSeries, E-Jets E2
CFM LEAP[38] 2013 9.0-11.0 3.15-3.33m 1.76-1.98m 2.78-3.15t 100-146 kN A320neo, B737Max
CFM56 1974 5.0-6.6 2.36-2.52m 1.52-1.84m 1.95-2.64t 97.9-151 kN A320, A340, B737, KC-135
IAE V2500 1987 4.4-4.9 3.20m 1.60m 2.36-2.54t 97.9-147 kN A320, MD-90
P&W PW6000 2000 4.90 2.73m 1.44m 2.36t 100.2 kN Airbus A318
R-R BR700 1994 4.2-4.5 3.41-3.60m 1.32-1.58m 1.63-2.11t 68.9-102.3 kN B717, Global Express, Gulfstream V
GE Passport 2013 5.6 3.37m 1.30m 2.07t 78.9–84.2 kN Global 7000/8000
GE CF34 1982 5.3-6.3 2.62-3.26m 1.25-1.32m 0.74-1.12t 41-82.3 kN Challenger 600, CRJ, E-jets
P&WC PW800 2012 5.5 1.30m 67.4-69.7 kN Gulfstream G500/G600
R-R Tay 1984 3.1-3.2 2.41m 1.12-1.14m 1.42-1.53t 61.6-68.5 kN Gulfstream IV, Fokker 70/100
Silvercrest 2012 5.9 1.90m 1.08m 1.09t 50.9 kN Cit. Hemisphere, Falcon 5X
R-R AE 3007 1991 5.0 2.71m 1.11m 0.72t 33,7 kN ERJ, Citation X
P&WC PW300 1988 3.8-4.5 1.92-2.07 0.97m 0.45-0.47t 23.4-35.6 kN Cit. Sovereign, G200, F. 7X, F. 2000
HW HTF7000 1999 4.4 2.29m 0.87m 0.62t 28.9 kN Challenger 300, G280, Legacy 500
HW TFE731 1970 2.66-3.9 1.52-2.08m .072-0.78m 0.34-0.45t 15.6-22.2 kN Learjet 70/75, G150, Falcon 900
Williams FJ44 1985 3.3-4.1 1.36-2.09m .53-0.57m 0.21-0.24t 6.7-15.6 kN CitationJet, Cit. M2
P&WC PW500 1993 3.90 1.52m 0.70m 0.28t 13.3 kN Citation Excel, Phenom 300
GE-H HF120 2009 4.43 1.12m 0.54 m 0.18t 7.4 kN HondaJet
Williams FJ33 1998 0.98m 0.53 m 0.14 t 6.7 kN Cirrus SF50
P&WC PW600 2001 1.8-2.8 0.67m 0.36m 0.15t 6.0 kN Cit. Mustang, Eclipse 500, Phenom 100

Extreme bypass jet engines[edit]




extra combustor immediately upstream of final nozzle (also called reheat)
afterburner on low-bypass turbofan engines.
Average stage loading
Bypass ratio
bypass airflow /core compression inlet airflow
turbomachinery handling the airstream that passes through the combustor.
Core power
Core thermal efficiency
core power/power equivalent of fuel flow
afterburner (if fitted) not lit
exhaust gas temperature
engine pressure ratio
turbofan LP compressor
Fan pressure ratio
fan outlet total pressure/intake delivery total pressure
Flex temp
use of artificially high apparent air temperature to reduce engine wear
Gas generator
engine core
HP compressor
high-pressure compressor (also HPC)
HP turbine
high-pressure turbine
Intake ram drag
integrated engine pressure ratio
IP compressor
intermediate pressure compressor (also IPC)
IP turbine
intermediate pressure turbine (also IPT)
LP compressor
low-pressure compressor (also LPC)
LP turbine
low-pressure turbine (also LPT)
Net thrust
Overall pressure ratio
combustor inlet total pressure/intake delivery total pressure
Overall efficiency
thermal efficiency * propulsive efficiency
Propulsive efficiency
Specific fuel consumption (SFC)
Spooling up
accelerating, marked by a delay
Static pressure
pressure of the fluid which is associated not with its motion but with its state[39]
Specific thrust
net thrust/intake airflow
Thermal efficiency
rate of production of propulsive kinetic energy/fuel power
Total fuel flow
Total pressure
static pressure plus kinetic energy term
Turbine rotor inlet temperature

See also[edit]


  2. ^ Hall, Nancy (May 5, 2015). "Turbofan Engine". Glenn Research Center. NASA. Retrieved October 25, 2015. Most modern airliners use turbofan engines because of their high thrust and good fuel efficiency. 
  3. ^ Michael Hacker; David Burghardt; Linnea Fletcher; Anthony Gordon, William Peruzzi (March 18, 2009). Engineering and Technology. Cengage Learning. p. 319. ISBN 978-1-285-95643-5. Retrieved October 25, 2015. All modern jet-powered commercial aircraft use high bypass turbofan engines [...]  Cite uses deprecated parameter |coauthors= (help)
  4. ^ Bharat Verma (January 1, 2013). Indian Defence Review: Apr-Jun 2012. Lancer Publishers. p. 18. ISBN 978-81-7062-259-8. Retrieved October 25, 2015. Military power plants may be divided into some major categories - low bypass turbofans that generally power fighter jets [...] 
  5. ^ Frank Northen Magill, ed. (1993). Magill's Survey of Science: Applied science series, Volume 3. Salem Press. p. 1431. ISBN 9780893567088. Most tactical military aircraft are powered by low-bypass turbofan engines. 
  6. ^ "Softtly, softly towards the quiet jet" Michael J.T.Smith, New Scientist, 19 February 1970, Figure 5
  7. ^ http://www.afmc.org.cn/13thacfm/invited/201.pdf
  8. ^ "Turbofan Engine". www.grc.nasa.gov. Retrieved 2010-11-24. 
  10. ^ "Turbojet History And Development 1930-1960 Volume 1", The Crowood Press Ltd. 2007, ISBN 978 1 86126 912 6, p.241
  13. ^ Decher, S., Rauch, D., “Potential of the High Bypass Turbofan,” American Society of Mechanical Engineers paper 64-GTP-15, presented at the Gas Turbine Conference and Products Show, Houston, Texas, March 1–5, 1964.
  14. ^ US Patent 3,390,527, High Bypass Ratio Turbofan, July 2, 1968.
  15. ^ RB211-535E4
  16. ^ ""The geared turbofan technology - Opportunities, challenges and readiness status"" (PDF).  C. Riegler, C. Bichlmaier:, 1st CEAS European Air and Space Conference, 10–13 September 2007, Berlin, Germany
  17. ^ Kempton, A, "Acoustic liners for modern aero-engines", 15th CEAS-ASC Workshop and 1st Scientific Workshop of X-Noise EV, 2011.
  18. ^ A. McAlpine "Research project: Buzz-saw noise and nonlinear acoustics"
  19. ^ Schuster, B., Lieber, L., & Vavalle, A., Optimization of a seamless inlet liner using an empirically validated prediction method. In 16th AIAA/CEAS Aeroacoustics Conference, Stockholm, Sweden.
  20. ^ Ferrante, P. G., Copiello, D., & Beutke, M.. Design and experimental verification of “true zero-splice” acoustic liners in the universal fan facility adaptation (UFFA) modular rig,”. In 17h AIAA/CEAS Aeroacoustics Conference, AIAA-2011-2728, Portland, OR.
  21. ^ a b c Banke, Jim (2012-12-13). "NASA Helps Create a More Silent Night". NASA. Retrieved January 12, 2013. 
  22. ^ Zaman, K.B.M.Q.; Bridges, J. E.; Huff, D. L. (17–21 December 2010). "Evolution from 'Tabs' to 'Chevron Technology'–a Review" (PDF-1.34 Mb). Proceedings of the 13th Asian Congress of Fluid Mechanics 17–21 December 2010, Dhaka, Bangladesh. NASA Glenn Research Center. Cleveland, Ohio. Retrieved January 29, 2013. 
  23. ^ Spittle, Peter. "Gas turbine technology" Rolls-Royce plc, 2003. Retrieved: 21 July 2012.
  24. ^ a b c Bjorn Fehrm (October 21, 2016). "Bjorn's Corner: The Engine challenge". Leeham News. 
  25. ^ "Flight Fleet Forecast's engine outlook". Flight Global. 2 November 2016. 
  26. ^ About Us | Engine Alliance
  27. ^ "International Aero Engines - History". IAE. 
  28. ^ Slaton, Hunter R., "Vault Guide to the Top Manuafacturing Employers", Vault Inc. (2nd Edition) 
  29. ^ FlightGlobal. "Honeywell gives AS907 turbofan redesignation." January 13, 2004. Retrieved March 5, 2012.
  30. ^ Flight International 13 January 2004
  31. ^ By Ernst-Heinrich Hirschel, Horst Prem and Gero Madelung. Published by Springer. "Aeronautical research in Germany: from Lilienthal until today, Volume 147." Page 427.
  32. ^ PS-90A turbofan, Aviadvigatel, 2011-01-17
  33. ^ Turbofan Engine Family for Regional Jet, Aviadvigatel, 2011-01-17
  34. ^ "Eurojet: Company profile". www.eurojet.de. Retrieved 2007-07-05. 
  35. ^ Jane's All the World's Aircraft. 2005. pp. 850–853. ISSN 0075-3017. 
  36. ^ "GEnx". GE. 
  37. ^ "PW1000G". MTU. 
  38. ^ "The Leap Engine". CFM International. 
  39. ^ Clancy, L.J., Aerodynamics, page 21

Further reading[edit]

  • Bargsten, Clayton J. "NASA Innovation in Aeronautics." NASA Innovation in Aeronautics NASA/TM-2011-216987 (2011): 11. NASA Innovation in Aeronautics. NASA, 1 Aug. 2011. Web.

External links[edit]