Jane's Aero-Engines

Jane's Aero-Engines provides comprehensive details of all civil and military gas-turbine engines (turbofans, turbojets, turboprops and turboshafts) currently in use worldwide for the propulsion of manned aircraft, listed in alphabetical order of countries. In addition to precise diagrams and illustrations to aid understanding and recognition, you will find detailed specifications of each engine, impartially presented to aid comparison and appraisal. Insightful descriptions of the background to each engine type, plus manufacturers' details, help support your procurement and market research needs.

The depth and breadth of information covers:

• Aircraft propulsion
• Gas turbine technology
• Engine development
• Engine cycles
• Military and civil engines

Different sections provide in-depth detail covering:

•    AERO-ENGINES - LIFTFAN
•    AERO-ENGINES - MANUFACTURER
•    AERO-ENGINES - PROPFAN
•    AERO-ENGINES - TURBOFAN
•    AERO-ENGINES - TURBOFAN/ - TURBOJET
•    AERO-ENGINES - TURBOFAN/ - TURBOPROP/ - TURBOSHAFT
•    AERO-ENGINES - TURBOJET
•    AERO-ENGINES - TURBOPROP
•    AERO-ENGINES - TURBOPROP/ - TURBOSHAFT
•    AERO-ENGINES - TURBOSHAFT
•    AIRCRAFT PROPULSION
•    ANALYSIS
•    CIVIL ENGINES
•    ENVIRONMENTAL FACTORS
•    GAS-TURBINE ENGINE CYCLES
•    GLOSSARY
•    INTRODUCTION TO AIRCRAFT GAS-TURBINE ENGINE TECHNOLOGY
•    MILITARY ENGINES
•    PERFORMANCE AND MANUFACTURER CHARTS
•    TECHNOLOGICAL ISSUES IN ENGINE DEVELOPMENT

Sections

• Aero-engines - liftfan
• Aero-engines - manufacturer
• Aero-engines - propfan
• Aero-engines - turbofan
• Aero-engines - turbofan/turbojet
• Aero-engines - turbofan/turboprop/turboshaft
• Aero-engines - turbojet
• Aero-engines - turboprop
• Aero-engines - turboprop/turboshaft
• Aero-engines - turboshaft
• Aircraft propulsion
• Analysis
• Civil engines
• Environmental factors
• Gas-turbine engine cycles
• Glossary
• Introduction to aircraft gas-turbine engine technology
• Military engines
• Performance and manufacturer charts
• Technological issues in engine development

Commonly Used Terms:
The standard US/NATO data-bus highway for digital data., Afterburner., See Temperature in section on Units following this glossary., Alternating Current., Removable items, not a part of the engine itself but essential to its operation or to that of the aircraft, such as a starter, fuel and lubricating-oil pumps, electric generator, hydraulic pump(s) and control systems., Use of cooling air to shrink a casing around a rotor to minimise air or gas leakage., Airworthiness Directive, order which must be obeyed immediately., Body shaped so that, as air flows across it, a force is generated perpendicular to the direction of flow, as in a wing, or a rotor blade or stator vane of an axial compressor (US often airfoil)., (US) Air Force Base., Enlarged jetpipe, fitted with a nozzle of variable profile and cross-section area, in which additional fuel can be burned to increase jet velocity and thus boost thrust for short periods. Normally found only on engines for supersonic aircraft., Turbofan in which the fan is a free-running assembly behind the core, driven by 'double-deck' inner blades in the jet from the core or a mechanically independent LP turbine., See bleed., Engine whose working fluid is primarily atmospheric air, and whose power thus tends to fall as altitude increases. A rocket is not such an engine., See aerofoil., Russian aircraft-engine scientific/technical complex., Abatement of Nuisance of Civil Air Transport ( UK)., The angle at which the air meets a wing or other aerofoil, such as a compressor blade., One in the form of a pure body of revolution comprising inner and outer cylindrical drums both centred on the engine's longitudinal axis., Air Navigation Order., Angle Of Attack., Automatic Power Reserve, an automatically scheduled increase in engine take-off power triggered by loss of power or thrust in another of the aircraft's engines., Auxiliary Power Unit, an easily started gas turbine supplying some of the following: shaft power, hydraulic power, electrical power, high-pressure air, and (in a few recent cases, mounted in the tail) emergency propulsive thrust., Aeronautical Radio Inc., Russian certification authority., See Pressure in section on Units following this glossary., Air TurnBack (mission abandoned)., Abandoned Take-Off., An afterburner attached behind a turbofan, with burning in both the core and bypass flows, or in the combined mixed flow., Compressor in which the air passes in succession through the spaces between a series of fixed radial stator vanes and moving rotor blades, each ring of stators and the immediately following rotor blades being called a stage. Each stage increases the pressure and temperature of the air., British Civil Airworthiness Requirements., A turboprop mode in which the pilot has direct control of propeller pitch., A certification requirement in which an engine, especially a large turbofan, must continue to operate and give thrust after ingesting a single large bird or a group of smaller birds of specified mass while running at maximum take-off power., Built-In Test Equipment (usually pronounced 'bite')., A radial aerofoil rotated about an axis to generate thrust, as in a propeller or axial-compressor rotor, or to convert gas energy to shaft power, as in a turbine rotor. UK usage often admits 'stator blade', but US usage calls stators vanes., Air piped away from a main-engine compressor to serve a purpose other than propulsion, such as pressurising the cabin, starting other engines, preventing icing or driving auxiliary machinery., A compressor or turbine rotor disc (US = disk) and its blades made as a single piece of material., Axial compressor (usually with from one to five stages) downstream of a fan and rotating with it (thus, at relatively low rpm, limited by the fan speed) to supercharge the core, to which all its airflow is delivered., ByPass Ratio., Device from which fuel or fuel vapour is delivered to the combustion chamber, surrounded by swirling primary air with minimal axial velocity. Generally synonymous with fuel nozzle., The duct surrounding the core through which the fan airflow passes, especially in an engine of low-BPR (in high-BPR engines, called the fan duct)., The numerical ratio of the mass flow entering the fan duct (inlet mass flow minus core flow) divided by that entering the core., Alternative term for a turbofan of low BPR (less than 1)., Civil Aviation Authority (UK)., Committee on Aviation Environmental Protection (ICAO)., A single combustion chamber, usually of circular cross-section, offset from the engine's axis and served by one or (in some P&W engines) several fuel nozzles. Small engines may have one such chamber, but usually several are arranged in a ring around the engine's longitudinal axis., Combustion chamber which, though of annular type, contains separate flame tubes downstream of each burner or burner group., Civil Air (Airworthiness) Regulations (FAA, CAA)., A rotor in the form of a disc with radial vanes on one side or on both sides. When rotated at high speed this flings the air off the rim at high speed. The kinetic energy is then converted to pressure in a surrounding diffuser., Carbon-Fibre Reinforced Plastics., Centre of gravity., Shaping a part by etching its surface in a bath of acid or similar corrosive liquid., Breadth of a blade, vane or wing from leading edge to trailing edge., Compression-Ignition, Turbine Engine (fuel)., Reverser comprising two curved deflectors, normally forming rear of nacelle, which swing on parallel arms to come together and block jet and deflect it forward., Part-span shroud., Ceramic-Matrix Composite., Carbon monoxide., Carbon dioxide., Without using the fitted afterburner., Combustion chamber, especially in US parlance., Comprising high-modulus (very strong and stiff) fibres formed into a useful structure by an adhesive matrix., Nozzle for generating a supersonic jet from an afterburner, initially convergent to a throat, and then divergent., Rotating machine controlled by a governor to rotate at a selected output speed, irrespective of variation in input speed or drive torque., Governor maintaining a preset propeller rotational speed, varying pitch according to airspeed and engine power., Certification requirement that, following any catastrophic mechanical failure inside an engine, no part shall be ejected through the casing, or out of the inlet or propulsive nozzle. The most severe demand is to contain a severed fan blade., Time-limited extra-high power rating, especially of a helicopter engine, following failure of another engine in the same aircraft. May be limited to 2.5 minutes or up to 30 minutes., Propellers, fans, compressors or other parts rotating in opposite directions on the same axis., Cost Of Ownership., That part of a turbofan which generates the power, comprising the compressor(s), combustion chamber(s) and turbines. In a turboshaft engine, commonly called the gas generator., A compressor immediately downstream from a fan and rotating with it, but delivering to the core only., In a flight by a transport aircraft, or any other flight whose purpose is to travel to a destination, the entire flight from top of climb to start of descent. Thus, cruise rating, cruise sfc., Constant-Speed Drive, usually for a constant-frequency alternator., Constant-Speed Unit, controlling the pitch of a propeller., Bleed air, shaft power, electric or other energy, apart from propulsion, required by the aircraft., Dual-Annular Combustor., See Force in Units section following this glossary., UK Defence Aviation Repair Agency., Diffusion Bonding, joining two metal parts by heat and pressure, to make atoms migrate across the boundary between the parts., Decibel(s), unit of sound energy, measured on a logarithmic scale as pressure level above local atmospheric pressure., One of several sound measures weighted (in this case A-weighted) to take into account human perception of loudness, unlike the dB which is a precise measure unrelated to the human ear., Direct Current., Digital Engine Control Unit., UK Defence Evaluation and Research Agency., Adjusting the engine control system to limit maximum power to less than that attainable., An engine developed directly from another., Passage whose cross-section area increases from inlet to outlet. A subsonic airflow through a diffuser slows down and increases in pressure, while a supersonic airflow accelerates and falls in pressure., Casting metal alloys in such a way that transverse grain boundaries are eliminated, leaving long columnar crystals with high strength along their axes., Department of Defense (USA)., Not using the engine's water-injection or reheat system., Exclusive of lubricating oil, fuel, water or other fluids., Directionally Solidified., Combustion chamber having two coaxial elements at different radii, each with its own ring of fuel nozzles. Both are used for high power, but one is shut down in cruising flight or other periods at low power., Fuel burner with a small spray nozzle, often called the primary nozzle, used continuously in cruising flight, surrounded by a much larger main nozzle which comes progressively into use as power is increased, for example, on take-off., Electron-Beam, hence EBW adds welded or welding., Engine Build-Up (assembly of new engine)., European Community., Equivalent horsepower, see equivalent power., Exhaust gas temperature, measured in the jetpipe downstream of the turbine., Engine indicating and crew-alerting system (pronounced Eye-cass)., Entry Into Service, or engine in-service date., Propelling nozzle for supersonic aircraft in which the jet from the engine entrains a large additional surrounding flow induced through inlets around the aft end of the fuselage., See equivalent shaft horsepower., Generally, a fuel control system in which throttles and other valves are controlled by electrical signals., The highest available rating, usually of a helicopter engine, typically time-limited to 30 s. Sometimes called Super Contingency., Effective Perceived Noise decibel, SI unit of EPNL., Effective Perceived Noise Level, derived from dBA by taking into account human subjective opinions of noise intensity, frequency, character and duration, and response of the human ear., In a turboprop, most of the energy in the gas is extracted by the power turbine to drive the propeller. Not all can be extracted, and, if the jetpipe is suitably designed, that remaining can be made to produce propulsive thrust. See next., Eshp, often shortened to equivalent horsepower (ehp), is calculated by dividing jet thrust in pounds by 2.6 (in the USA, by 2.5) and adding the result to the shp. Thus, ekW (equivalent kilowatts) is the corresponding SI unit based on Watts and Newtons., See preceding entry., Engine-Section Stator, the guide vanes at entry to the LP compressor., Extended-range twin-engine operations, certification of a twin-engined aircraft and its particular engine type to fly for hire or reward up to 120, 180 or 205 minutes away from the nearest available runway. This is normally interpreted as permitting transoceanic flights., At an airport, one landing or take-off., Federal Aviation Administration (USA)., Usually means welded., Full-Authority Digital Engine (or electronic) Control, in which computers manage every aspect of operation of the propulsion system, under the pilot's surveillance., Rotor with multiple radial blades which compress a much larger airflow than that passing through the core. In a low-BPR engine the fan may have several stages and be in effect a slightly oversized LP compressor. In a high-BPR engine the fan usually has a single stage, with a pressure ratio of 1.3 to 1.8, and becomes increasingly like a multi-bladed shrouded propeller., Severe test in civil-turbofan certification, in which a fan blade is deliberately severed at the root while the engine is running at redline speed (a rotational speed never reached in normal operation). The engine must contain the blade and be capable of being shut down without catastrophic failure., The annular duct through which the air compressed by the fan is delivered. In a high-BPR engine it is often short, ending in an annular propulsive nozzle part-way along the nacelle. For increased propulsive efficiency the fan airflow is sometimes mixed with the core jet to emerge through a common nozzle., Turbofan, or turbofan-engined aircraft (colloquial)., Federal Aviation Regulation(s)., Fan-Blade Off (also, fixed-base operator)., Setting the angle of attack of the blades of a propeller so that, when the engine is shut down, the windmilling torque of the passing air is zero, stopping rotation. This gives minimum drag, and prevents further damage to a failed engine., First Engine (of a new type) To Test., Method of retaining blades (usually of a turbine) in a disc or ring by accurate machining or grinding to a shape resembling a fir tree, so that the load (mainly centrifugal) is shared by multiple faces on each side of the blade's major axis., A ring or other shape placed in an afterburning jetpipe to create local turbulence and reversed airflow (typically by having profile with the open side facing downstream) so that injected fuel has time to burn completely before being swept out of the engine., A rating (thrust or shaft power) which does not fall off with increasing airfield height or ambient temperature but remains at the full (usually sea-level) value up to a given 'kink point'., Fuel-Management Unit., Foreign-Object Damage, caused by ingesting solid material (such as stones, hand tools, hail or birds) into the engine., A combustion chamber in which the air passes along the outside of the flame tube or liner towards fuel nozzle(s) at the rear, and there changes direction by 180° to flow along the interior. A second 180° turn is then usually required to flow rearwards through the turbine., Graphical plot of the area around an airport within which the noise (Approach, Sideline and Flyover) of a particular event, or a generalised figure for a particular aircraft type, exceeds a specified value., Fan Pressure Ratio., A turbine free to rotate independently of the core (gas generator), driven by the core gas flow at a speed determined by the output torque (fan, propeller or helicopter shaft)., Fiscal Year; in the case of the US DoD, or other government office, beginning on 1 October, thus FY04 ran from 1 October 2003 to 30 September 2004., Acceleration caused by Earth's gravity, or by a rapid change in direction of the flight path., See Volume in Units section following this glossary., The power-producing part of a gas turbine. Generally synonymous with 'core', though a gas generator can run by itself to supply gas to a remote turbine or tip-drive helicopter rotor., Turbine driven by a flow of hot gas; usually taken also to mean an engine containing a turbine of this type., Positive-displacement pump in which two meshing gears carry parcels of liquid round between successive teeth and the inner wall of a tight-fitting casing., Glass-Fibre Reinforced Plastics., A new version of an engine offering significantly increased power., Hour(s)., Rotating in opposite directions, on different axes., High-ByPass Ratio., Shorthand for mixtures of various unburned hydrocarbons emitted from an engine., High-Cycle Fatigue, which usually means that each revolution of a shaft (or each application of a rapidly varying load) is counted as one fatigue cycle., Not strictly defined, but today generally taken to mean BPR >=5., That which has logged the greatest running time (usually equated with flight time) of the entire population of that engine type., Airfield, or helicopter platform, where high ambient temperature is combined with high altitude above sea level. Both factors reduce air density and thus gas-turbine power, whilst simultaneously reducing the lift from a wing or rotor., Everything downstream of the compressor(s)., High-Pressure., Horsepower., High-Pressure Compressor., High-Pressure Turbine., Hot-Section Inspection., Operated by liquid pressure, such as hydraulic oil, lubricating oil or fuel., Hertz, unit of frequency = cycles/s., International Civil Aviation Organisation., Integrated-Drive Generator., In-Flight ShutDown (rate)., See Volume in Units section following this glossary., Addition to the inlet of a gas turbine, notably on helicopter turboshaft engines, which diverts ingested solid matter and prevents it from entering the engine., Blades of a compressor or turbine rotor not forming an integral (monolithic) part of a disc., Electric AC generator (alternator) incorporating a CSD., Also called Intermediate Contingency, rating of a helicopter engine between Maximum Contingency (or Emergency) and Continuous, typically time-limited to 30 or 60 min., Term applicable only to three-shaft engines, in which the IP system (compressor, shaft and turbine) lies between the HP and LP., Intermediate Pressure, of a three-shaft engine., Inlet Particle Separator., Infra-red., International Standard Atmosphere., Inspection Service Bulletin., Joint Aviation Authority, regulations adopted by Austria, Belgium, Cyprus, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Monaco, Netherlands, Norway, Poland, Portugal, Slovenia, Spain, Sweden, Switzerland and the United Kingdom, with applications to join from others., Joint Aviation Regulations, published by the JAA., Any turbojet or turbofan (and, in principle, rockets and ramjets, not covered in this publication)., Pipe through which the gas from the core (in a turbojet, turboshaft or turboprop, from the whole engine) is discharged to atmosphere., JetPipe Temperature, usually synonymous with EGT., See Temperature in Units section following this glossary., Kilogram(s). See Units (Mass)., A point on a graph, or plotted value of a parameter, where there is a sudden alteration in rate of change, or where the plotted value falls from the maximum, as when ambient temperature exceeds the limit for a flat-rated engine to maintain maximum power., Kilometre(s) per hour. See Units (Velocity)., Kilonewton(s). See Units (Force)., Knot(s). See Units (Velocity)., Kilowatt(s). See Units (Power)., Pound(s) of thrust. See Units (Force)., Pounds force. See Units (Force)., Low-Cycle Fatigue, usually means that each cycle of applied load = one flight., SI unit of volume. See Units (Volume)., Life-Limited Part(s)., Liquefied Natural Gas., Low-Pressure., Low-Pressure Compressor. This term is often used to mean a core booster., Liquefied Petroleum Gas., Low-Rate Initial Production., Low-Pressure Turbine., Line-Replaceable Unit, a functional part treated as an independent entity, which can be replaced with the aircraft on the apron or flight line., Metre(s). See Units (Length)., Mach number, aircraft speed divided by the speed of sound in the surrounding air. Also sometimes rendered as Mn., Mass of air passing through an engine or any of its components per second., Main Fuel Control., Milligrams. See Units (Mass)., Military (US usage), which when applied to a rating implies maximum continuous power, or maximum cold thrust., Engine design bureau (Russia, Ukraine)., Millimetres. See Units (Length)., Designed as an assemblage of discrete modules (for example, fan and case, compressor, combustion chamber and turbine section), each of which can readily be replaced independently of the others should it develop a fault., Turbine rotor blade (or any other part) formed in a piece of metal grown as a single crystal, with no inter-grain boundaries to weaken it mechanically., Literally 'single-rock', synonymous with mono-crystal., Miles per hour. See Units (Velocity)., Model Qualification Test., Maintenance, Repair and Overhaul., Mean Time Between Failures., Mean Time Between Repairs., Maximum Take-Off Weight of an aircraft; MTOGW adds gross., Newton. See Units (Force)., Shaft speeds of different parts of an engine are often denoted by shorthand of this type, but as numbers now extend to at least 9 this usage is avoided in this publication., Nozzle Guide Vane, also called turbine stator, to direct gas flow on to rotor blades at optimum angle., Noise and Number Index, calculated for a given point near an airfield from measures of EPNdB and number of aircraft events., Russian term for maximum continuous., At 90°, thus a normal shock is perpendicular to the airflow direction., Shorthand for all oxides of nitrogen generated by burning fuel in air., Confusingly, this term is used not only for the propulsive nozzle of a jet engine, where the jet(s) escape to atmosphere, but also (US usage) for a fuel burner, and also for the ring of stator vanes (or, rather, the gaps between them) at the entry to a turbine., US National Transportation Safety Board., One Engine (of a multi-engine aircraft) Inoperative., Original-Equipment Manufacturer., Outlet Guide Vane(s) downstream of a rotating assembly, such as a fan or turbine, to change the flow from spiral to truly axial., Experimental construction (= design) bureau (Russia, Ukraine)., With the engine installed in the aircraft, not necessarily hung under a wing., Removed from the aircraft., Overall Pressure Ratio., Ratio of the pressure at the delivery to the combustion chamber to that at the compressor inlet (the latter being taken as unity, so that an OPR of 26:1 can be written as 26). OPR is the product of FPR × compressor PR., Projections near the mid-length of a fan or compressor blade which, when the rotor is assembled, form a continuous ring to damp out flutter or other vibration. Also called a clapper, damper or snubber., SI unit of pressure, 1 Pa = 1 N/m2 (but not used in this publication)., Preliminary Flight Rating Test., Angular setting of a propeller blade (strictly, distance advanced through air in one revolution if slip were zero)., Subject to full ram pressure, for example, a simple forward-facing intake (pronounced peeto)., Actuated by compressed air, either by a piston or, in the case of a pneumatic starter, by an air turbine., On the left side, looking forward., Gas generator, a term commonly used where two gas generators drive a common output gearbox., In a free-turbine turboprop or turboshaft, the turbine driving the output, not the compressor., Pressure Ratio., For a compressor, the ratio of the pressure at the delivery divided by that at the inlet (the latter pressure being numerically taken as unity). In a supersonic aircraft there may be an even greater PR across the aircraft inlet. See OPR., That taking place surrounding the fuel nozzle and immediately downstream., Funding for tooling to make an item at a planned rate., Gas-turbine engine in which thrust is generated by a propeller with multiple (usually six or more) blades of exceptionally thin profile, sharp edges and a curved scimitar-like planform. For highest efficiency two such propellers counter-rotate. The propellers may be open or shrouded. Such an engine 'gives turboprop economy at jet speed'., Thrust generator of a tilt-rotor aircraft; can be considered as a high-speed helicopter rotor or as an oversized propeller., Quota Count (a method of assessing noise at airports)., Pressure above that of the local atmosphere caused by air being rammed into an inlet, where its relative velocity (kinetic energy) is converted into pressure. The effect is dominant at high supersonic Mach numbers., Any of several defined levels of power or thrust published for a particular type or model of engine, qualified according to the regime: take-off, maximum climb, maximum cruise (continuous), OEI contingency, and so on., The maximum permitted rotational speed of a fan or compressor, allowable for a brief period only. Never reached in normal operation., Gearbox which reduces rotational speed (increasing torque in the same ratio)., Duplicating or triplicating a vital item or flow-path so that correct operation is continued after failure of any one part., A turbofan fitted with a larger fan than its original, to increase its BPR., Use of an afterburner (UK term)., Maintenance of full design performance over a long period in service., Mechanical device for redirecting the jet from a jet engine diagonally forwards in order to slow the aircraft (usually after landing). In high-BPR turbofans it is usual to divert the fan airflow only., In an engine, any assembly that rotates, as distinct from NGVs or stators., Revolutions per minute, measure of rotational speed., Risk and revenue Sharing Partners., Reduced-Temperature Configuration., Second (time measure)., Specific fuel consumption. See Units., Connection joining two rotating assemblies, one driving and the other driven, especially a turbine and compressor. A two-shaft engine has an HP shaft rotating at high speed surrounding the central LP shaft. A three-shaft engine has an IP shaft interposed between the LP and HP., Power transmitted by a rotating shaft, measured as torque (in lb-ft or kg-m) multiplied by rpm, units being compatible. See Power in Units section following this glossary., One item delivered from manufacturer to customer., Frequency, measured in occasions per unit of flight-time (such as per 100,000 h) with which a particular type of engine has to be removed from the aircraft for repair or overhaul. This measure is usually a global fleet average., Shaft horsepower. See Units (Power)., 1) Projecting plate formed on a rotating blade perpendicular to the blade's major axis, such that when the rotor is assembled the projections form an unbroken ring. In a fan blade they are usually near mid-span, to damp out flutter (also called a part-span shroud, clapper or snubber). In a turbine blade they are at the tip, to minimise gas leakage., 2) A fixed ring or duct surrounding a propfan or high-BPR fan., Characteristic spectrum of radar reflectivity, noise or IR emission from an object., See mono-crystal., One having only one major rotating assembly of turbine and compressor., Sea level., Part-span shroud., Net thrust divided by total inlet mass flow., In engines, rotational speed in rpm., Streamlined fairing over the hub of a propeller, front fan or engine front bearing. In the last case the spinner does not rotate., A compressor rotor, and turbine rotor assembly. Thus, a two-shaft turbojet has an LP spool surrounded by an HP spool., SuperPlastic Forming., SuperSonic Transport., Static thrust, imparted by an engine at rest relative to the surrounding air., In a fan, compressor or turbine, one complete ring of rotating blades together with associated NGVs or stators. Normally applied to axial stages of compression or expansion., At ISA temperature and pressure., On the right side, looking forward., At rest relative to the surrounding air, so that ram pressure rise is zero., The fixed part of a compressor or turbine, especially of axial type, comprising the vanes or NGVs and casing. In 'variable stator', loosely applied to mean the stator vanes only., Short Take-Off., Short Take-Off and Landing., Short Take-Off, Vertical Landing., The lowest part(s) of an engine in which lubricant and other fluids collect., Shop-Visit Rate., Technology for advanced low NOx., Twin-Annular, Pre-Swirl., Time Between Overhauls., Turbine-Entry Temperature, usually the mean value of the temperature of the gas immediately upstream of the first HP rotor. Because of cooling airflows, this is cooler than CET (Combustor Exit Temperature) and SOT (Stator Outlet Temperature)., Turbine Gas Temperature, usually measured at the LP turbine entry., Engine with an HP turbine driving an HP compressor via a shaft surrounding that which joins an IP turbine to an IP compressor, which in turn surrounds that joining an LP turbine to an LP compressor or fan. A few three-shaft engines (for example, the Honeywell ATF3) have a different arrangement., The point of minimum cross-section area of a venturi or other constriction in a duct., See shroud., Take-Off., System in which oil is passed through bearings and gears and then ejected overboard., Turbofan Pressure Ratio, a type of engine control system., Speeds close to the local speed of sound., Rotor carrying blades which extract energy from a flow of hot gas in order to turn a shaft., Gas-turbine engine in which part of the thrust (the proportion depending upon BPR) is generated by a fan, the remainder being generated by the core., The simplest gas-turbine, comprising an inlet, compressor, combustion chamber, turbine and suitable thrust-producing nozzle., Gas-turbine engine in which as much of the gas energy as possible is converted into shaft power to drive a reduction gearbox which drives a propeller., Gas-turbine engine in which as much of the gas energy as possible is converted into shaft power which drives a high-speed shaft (not part of the engine) connected to the helicopter main gearbox, which drives the rotors., Thrust Vector Control., Engine with an HP turbine driving an HP compressor via a shaft surrounding that joining the LP turbine to the LP compressor or fan. A common UK usage is two-spool. In the case of a turboprop or turboshaft the adjective means a free-turbine engine., Describes a process achieved in two parts. In the Honeywell TPE331, for example, the propeller is driven by a two-stage gearbox in which both stages operate simultaneously, whereas the air flows through the two parts of its two-stage compressor consecutively., Unscheduled Engine Removal, or unscheduled engine-removal rate., Descriptive of a turbine blade devoid of internal or transpiration cooling., See Units (Volume)., US term for aerofoil blades, usually in a ring, to guide the flow into a fan, compressor or turbine. See stator., When applied to an inlet guide vane or stator, means variable incidence or pitch. When applied to an inlet or nozzle, means variable profile and cross-section area., Capable of being pointed in a chosen direction., Duct whose cross-section contracts to a minimum at a throat and then expands (usually to the original value or greater)., Variable Inlet Guide Vane(s)., Vertical Lift., Vertical or Short Take-Off and Landing., Variable Stator Vane(s)., Spraying demineralised water, or a mixture with (usually methyl) alcohol, into the inlet to a compressor or combustion chamber to reduce the temperature and thus increase the density of the airflow, and so increase power., Rotation of a failed or otherwise inoperative engine by an unfeathered propeller or airflow through the fan or core., An extra stage of axial-flow blading added on the front of a compressor to increase both mass flow and pressure ratio. Hence, zero-zero stage, addition of a further stage in front of a zero stage.

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