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62-542: IRST is a generalized case of Forward Looking Infrared (FLIR), i.e. from forward-looking to all-round situation awareness . Such systems are passive ( thermographic camera ), meaning they do not give out any radiation of their own, unlike radar . This gives them the advantage that they are difficult to detect. However, because the atmosphere attenuates infrared to some extent (although not as much as visible light ) and because adverse weather can attenuate it also (again, not as badly as visible systems), their range compared to

124-755: A heat source ( thermal radiation ), to create an image assembled for video output. They can be used to help pilots and drivers steer their vehicles at night and in fog, or to detect warm objects against a cooler background. The wavelength of infrared that thermal imaging cameras detect is 3 to 12  μm and differs significantly from that of night vision , which operates in the visible light and near-infrared ranges (0.4 to 1.0  μm). Infrared light falls into two basic ranges: long-wave and medium-wave . Long-wave infrared (LWIR) cameras, sometimes called "far-infrared", operate at 8 to 12 μm and can see heat sources, such as hot engine parts or human body heat , several kilometers away. Longer-distance viewing

186-483: A turbofan application). The first designs, e.g. Solar afterburners used on the F7U Cutlass, F-94 Starfire and F-89 Scorpion, had 2-position eyelid nozzles. Modern designs incorporate not only variable-geometry (VG) nozzles but multiple stages of augmentation via separate spray bars. To a first order, the gross thrust ratio (afterburning/dry) is directly proportional to the root of the stagnation temperature ratio across

248-530: A C.C.2, with its afterburners operating, took place on 11 April 1941. Early British afterburner ("reheat") work included flight tests on a Rolls-Royce W2/B23 in a Gloster Meteor I in late 1944 and ground tests on a Power Jets W2/700 engine in mid-1945. This engine was destined for the Miles M.52 supersonic aircraft project. Early American research on the concept was done by NACA , in Cleveland, Ohio, leading to

310-482: A bigger engine with its attendant weight penalty, but at the cost of increased fuel consumption (decreased fuel efficiency ) which limits its use to short periods. This aircraft application of "reheat" contrasts with the meaning and implementation of "reheat" applicable to gas turbines driving electrical generators and which reduces fuel consumption. Jet engines are referred to as operating wet when afterburning and dry when not. An engine producing maximum thrust wet

372-452: A counterexample, the SR-71 had reasonable efficiency at high altitude in afterburning ("wet") mode owing to its high speed ( mach 3.2) and correspondingly high pressure due to ram intake . Afterburning has a significant influence upon engine cycle choice. Lowering the fan pressure ratio decreases specific thrust (both dry and wet afterburning), but results in a lower temperature entering

434-431: A demonstrator engine was run. The duct heater used an annular combustor and would be used for takeoff, climb and cruise at Mach 2.7 with different amounts of augmentation depending on aircraft weight. A jet engine afterburner is an extended exhaust section containing extra fuel injectors. Since the jet engine upstream (i.e., before the turbine) will use little of the oxygen it ingests, additional fuel can be burned after

496-529: A horizontally rotating shutter in front of it. The shutter was slaved to a display under the main interception radar display in the cockpit. Any IR light falling on the sensor would generate a "pip" on the display, in a fashion similar to the B-scopes used on early radars. The display was primarily intended to allow the radar operator to manually turn the radar to the approximate angle of the target, in an era when radar systems had to be "locked on" by hand. The system

558-457: A limit to the number of targets simultaneously tracked. When they find one or more potential targets they will alert the pilot(s) and display the location of each target relative to the aircraft on a screen, much like a radar. Again similarly to the way a radar works, the operator can tell the IRST to track a particular target of interest, once it has been identified, or scan in a particular direction if

620-471: A low specific thrust (low fan pressure ratio/high bypass ratio) cycle will be favored. Such an engine has a good dry SFC, but a poor afterburning SFC at Combat/Take-off. Often the engine designer is faced with a compromise between these two extremes. The Caproni Campini C.C.2 motorjet , designed by the Italian engineer Secondo Campini , was the first aircraft to incorporate an afterburner. The first flight of

682-562: A radar is limited. Within range, an IRST's angular resolution is better than radar due to the shorter wavelength . The first uses of an IRST system appeared in the F-101 Voodoo , F-102 Delta Dagger and F-106 Delta Dart interceptors . The F-106 had an early IRST mounting replaced in 1963 with a production retractable mount. The IRST was also incorporated into the F-8 Crusader (F-8E variant) allowing passive tracking of heat emissions and

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744-628: A regular magnified optical sight slaved to it, to help the IRST-equipped aircraft identify the target at long range. As opposed to an ordinary forward looking infrared system, an IRST system will actually scan the space around the aircraft similarly to the way in which mechanically (or even electronically) steered radars work. The exception to the scanning technique is the F-35's DAS, which stares in all directions simultaneously, and automatically detects and declares aircraft and missiles in all directions, without

806-451: A short distance and causes visible banding where pressure and temperature are highest. Thrust may be increased by burning fuel in a turbofan's cold bypass air, instead of the mixed cold and hot flows as in most afterburning turbofans. An early augmented turbofan, the Pratt & Whitney TF30 , used separate burning zones for the bypass and core flows with three of seven concentric spray rings in

868-408: A small IRST under the nose. The Swedish Saab J-35F2 Draken (1965) also used an IRST, a Hughes Aircraft Company N71. IRST systems re-appeared on more modern designs starting in the 1980s with the introduction of 2-D sensors, which cued both horizontal and vertical angle. Sensitivities were also greatly improved, leading to better resolution and range. In more recent years, new systems have entered

930-415: A target is believed to be there (for example, because of an advisory from AWACS or another aircraft). IRST systems can incorporate laser rangefinders in order to provide full fire-control solutions for cannon fire or launching missiles ( Optronique Secteur Frontal ). The combination of an atmospheric propagation model, the apparent surface of the target, and target motion analysis (TMA) IRST can calculate

992-443: Is an additional combustion component used on some jet engines , mostly those on military supersonic aircraft . Its purpose is to increase thrust , usually for supersonic flight , takeoff, and combat . The afterburning process injects additional fuel into a combustor ("burner") in the jet pipe behind (i.e., "after") the turbine , "reheating" the exhaust gas. Afterburning significantly increases thrust as an alternative to using

1054-410: Is at maximum power, while an engine producing maximum thrust dry is at military power . The first jet engine with after-burner was the E variant of Jumo 004 . Jet-engine thrust is an application of Newton's reaction principle, in which the engine generates thrust because it increases the momentum of the air passing through it. Thrust depends on two things: the velocity of the exhaust gas and

1116-420: Is called an "afterburning turbojet", whereas a turbofan engine similarly equipped is sometimes called an "augmented turbofan". A " dump-and-burn " is an airshow display feature where fuel is jettisoned, then intentionally ignited using the afterburner. A spectacular flame combined with high speed makes this a popular display for airshows , or as a finale to fireworks . Fuel dumping is used primarily to reduce

1178-451: Is highest when combustion occurs at the highest pressure and temperature possible, and expanded down to ambient pressure (see Carnot cycle ). Since the exhaust gas already has a reduced oxygen content, owing to previous combustion, and since the fuel is not burning in a highly compressed air column, the afterburner is generally inefficient in comparison to the main combustion process. Afterburner efficiency also declines significantly if, as

1240-506: Is made more difficult with LWIR because the infrared light is absorbed , scattered , and refracted by air and by water vapor. Some long-wave cameras require their detector to be cryogenically cooled, typically for several minutes before use, although some moderately sensitive infrared cameras do not require this. Many thermal imagers, including some forward-looking infrared cameras (such as some LWIR enhanced vision systems (EVS)) are also uncooled. Medium-wave (MWIR) cameras operate in

1302-437: Is used to pick up and track the target once the fighter is in range. Forward Looking Infrared Forward-looking infrared ( FLIR ) cameras, typically used on military and civilian aircraft, use a thermographic camera that senses infrared radiation . The sensors installed in forward-looking infrared cameras, as well as those of other thermal imaging cameras, use detection of infrared radiation, typically emitted from

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1364-406: Is usually the case, the inlet and tailpipe pressure decreases with increasing altitude. This limitation applies only to turbojets. In a military turbofan combat engine, the bypass air is added into the exhaust, thereby increasing the core and afterburner efficiency. In turbojets the gain is limited to 50%, whereas in a turbofan it depends on the bypass ratio and can be as much as 70%. However, as

1426-767: The English Electric Lightning , the first supersonic aircraft in RAF service. The Bristol-Siddeley/ Rolls-Royce Olympus was fitted with afterburners for use with the BAC TSR-2 . This system was designed and developed jointly by Bristol-Siddeley and Solar of San Diego. The afterburner system for the Concorde was developed by Snecma . Afterburners are generally used only in military aircraft, and are considered standard equipment on fighter aircraft. The handful of civilian planes that have used them include some NASA research aircraft,

1488-496: The FBI conducted 10 aerial surveillance missions between April 29 and May 3, which included "infrared and day color, full-motion FLIR video evidence" collection, according to FBI spokesman Christopher Allen. A FLIR Talon multi-sensor camera system equipped with an infrared laser pointer (which is invisible to casual observers) for illumination purposes was used to gather data at night. The American Civil Liberties Union raised concerns over

1550-532: The Supreme Court of Canada determined that the use of airborne FLIR in surveillance by police was permitted without requiring a search warrant. The Court determined that the general nature of the data gathered by FLIR did not reveal personal information of the occupants and therefore was not in violation of Tessling's Section 8 rights afforded under the Charter of Rights and Freedoms (1982). Ian Binnie distinguished

1612-566: The Tupolev Tu-144 , Concorde and the White Knight of Scaled Composites . Concorde flew long distances at supersonic speeds. Sustained high speeds would be impossible with the high fuel consumption of afterburner, and the plane used afterburners at takeoff and to minimize time spent in the high-drag transonic flight regime. Supersonic flight without afterburners is referred to as supercruise . A turbojet engine equipped with an afterburner

1674-587: The United States Supreme Court decided in Kyllo v. United States that performing surveillance of private property (ostensibly to detect high emission grow lights used in clandestine cannabis farming) using thermal imaging cameras without a search warrant by law enforcement violates the Fourth Amendment's protection from unreasonable searches and seizures. In the 2004 R. v. Tessling judgment,

1736-410: The 3–5 μm range. These can see almost as well, since those frequencies are less affected by water-vapor absorption, but generally require a more expensive sensor array , along with cryogenic cooling. Many camera systems use digital image processing to improve the image quality. Infrared imaging sensor arrays often have wildly inconsistent sensitivities from pixel to pixel, due to limitations in

1798-527: The AAA-4 IRST bulge and received an internal gun mount which took up the area under the nose. The F-4J which had a pulse-Doppler radar also eliminated the AAA-4 IRST receiver and bulge under the nose. The first use of IRST in an Eurasian country was the Mikoyan-Gurevich MiG-23 , which used the (TP-23ML) IRST; later versions used the (26SH1) IRST. The Mikoyan-Gurevich MiG-25 PD was also equipped with

1860-603: The Canadian National Aerial Surveillance Program DHC-8M-100 aircraft mounted with infrared sensors was instrumental in the search for Justin Bourque , a fugitive who had killed three Royal Canadian Mounted Police members in Moncton . The plane's crew used its advanced heat-sensing camera to discover Bourque's heat signature in the deep brushwoods at midnight. During 2015 Baltimore protests ,

1922-506: The Canadian law with respect to the Kyllo judgment, by agreeing with the Kyllo minority that public officials should not have to avert their senses or their equipment from detecting emissions in the public domain such as excessive heat, traces of smoke, suspicious odors, odorless gases, airborne particulates, or radioactive emissions, any of which could identify hazards to the community. In June 2014,

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1984-615: The Raytheon AN/AAQ-26 are used in a variety of applications, including naval vessels , fixed-wing aircraft , helicopters , armored fighting vehicles , and military-grade smartphones . In warfare, they have three distinct advantages over other imaging technologies: The term "forward-looking" is used to distinguish fixed forward-looking thermal imaging systems from sideways-tracking infrared systems, also known as " push broom " imagers, and other thermal imaging systems such as gimbal-mounted imaging systems, handheld imaging systems, and

2046-664: The addition of a second scan mirror, the invention of the first forward-looking infrared camera occurred in 1963, with production beginning in 1966. In 1972, TI introduced the Common Module concept, which greatly reduced costs and allowed for the reuse of common components. The cost of thermal imaging equipment in general has fallen dramatically after inexpensive portable and fixed infrared detectors and systems based on microelectromechanical technology were designed and manufactured for commercial, industrial, and military application. Also, older camera designs used rotating mirrors to scan

2108-478: The afterburner (i.e. exit/entry). Due to their high fuel consumption, afterburners are only used for short-duration, high-thrust requirements. These include heavy-weight or short-runway take-offs, assisting catapult launches from aircraft carriers , and during air combat . A notable exception is the Pratt & Whitney J58 engine used in the SR-71 Blackbird which used its afterburner for prolonged periods and

2170-413: The afterburner results in a good thrust boost. If the aircraft burns a large percentage of its fuel with the afterburner alight, it pays to select an engine cycle with a high specific thrust (i.e. high fan pressure ratio/low bypass ratio ). The resulting engine is relatively fuel efficient with afterburning (i.e. Combat/Take-off), but thirsty in dry power. If, however, the afterburner is to be hardly used,

2232-399: The afterburner. Since the afterburning exit temperature is effectively fixed, the temperature rise across the unit increases, raising the afterburner fuel flow. The total fuel flow tends to increase faster than the net thrust, resulting in a higher specific fuel consumption (SFC). However, the corresponding dry power SFC improves (i.e. lower specific thrust). The high temperature ratio across

2294-406: The afterburner. The mass flow is also slightly increased by the addition of the afterburner fuel. The thrust with afterburning is 16,000 lb f (71,000 N). The visible exhaust may show shock diamonds , which are caused by shock waves formed due to slight differences between ambient pressure and the exhaust pressure. This interaction causes oscillations in the exhaust jet diameter over

2356-414: The aircraft for full spherical coverage, providing day/night imaging and acting as an IRST and missile approach warning system. Chengdu J-20 and Shenyang FC-31 is assumed to share the similar design concept with their system. IRST systems can also be used to detect stealth aircraft, in some cases, outperforming traditional radar. These were fairly simple systems consisting of an infra-red sensor with

2418-420: The better transmission of infrared radiation. Therefore, infrared detection ranges are longer at high altitudes. At high altitudes, temperatures range from −30 to −50 °C - which provide better contrast between aircraft temperature and background temperature. The Eurofighter Typhoon's PIRATE IRST can detect subsonic fighters from 50 km from the front and 90 km from the rear - the larger value being

2480-460: The bypass flow. In comparison, the afterburning Rolls-Royce Spey used a twenty chute mixer before the fuel manifolds. Plenum chamber burning (PCB) was partially developed for the vectored thrust Bristol Siddeley BS100 engine for the Hawker Siddeley P.1154 until the program was cancelled in 1965. The cold bypass and hot core flows were split between two pairs of nozzles, front and rear, in

2542-414: The consequence of directly observing the engine exhaust, with an even greater increase being possible if the target uses afterburners . The range at which a target can be identified with sufficient confidence to decide on weapon release is significantly inferior to the detection range - manufacturers have claimed it is about 65% of the detection range. With infrared homing or fire-and-forget missiles,

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2604-413: The design tradeoff is a large size relative to the power output. Generating increased power with a more compact engine for short periods can be achieved using an afterburner. The afterburner increases thrust primarily by accelerating the exhaust gas to a higher velocity. The following values and parameters are for an early jet engine, the Pratt & Whitney J57 , stationary on the runway, and illustrate

2666-435: The effective afterburner fuel flow), but a decrease in afterburner exit stagnation pressure (owing to a fundamental loss due to heating plus friction and turbulence losses). The resulting increase in afterburner exit volume flow is accommodated by increasing the throat area of the exit nozzle. Otherwise, if pressure is not released, the gas can flow upstream and re-ignite, possibly causing a compressor stall (or fan surge in

2728-526: The engine. The combustion products have to be diluted with air from the compressor to bring the gas temperature down to a specific value, known as the Turbine Entry Temperature (TET) (1,570 °F (850 °C)), which gives the turbine an acceptable life. Having to reduce the temperature of the combustion products by a large amount is one of the primary limitations on how much thrust can be generated (10,200 lb f (45,000 N)). Burning all

2790-543: The fact that new surveillance technology is implemented without judicial guidance and public discussion. According to Nathan Wessler, an ACLU attorney, "this is a dynamic we see again and again when it comes to advances in surveillance. By the time details leak out, programs are firmly entrenched, and it's all but impossible to roll them back – and very hard to put in place restrictions and oversight." Afterburners An afterburner (or reheat in British English)

2852-412: The fighter may be able to fire upon the target without having to turn on its radar sets on at all. Otherwise, the fighter can turn the radar on and achieve a lock immediately before firing if desired. The fighter could also close to within cannon range and engage that way. Whether or not they use their radar, the IRST system can still allow them to launch a surprise attack. An IRST system may also have

2914-418: The gas flow has left the turbines. When the afterburner is turned on, fuel is injected and igniters are fired. The resulting combustion process increases the afterburner exit ( nozzle entry) temperature, resulting in a significant increase in engine thrust. In addition to the increase in afterburner exit stagnation temperature , there is also an increase in nozzle mass flow (i.e. afterburner entry mass flow plus

2976-412: The high values of afterburner fuel flow, gas temperature and thrust compared to those for the engine operating within the temperature limitations for its turbine. The highest temperature in the engine (about 3,700 °F (2,040 °C) ) occurs in the combustion chamber, where fuel is burned (at an approximate rate of 8,520 lb/h (3,860 kg/h)) in a relatively small proportion of the air entering

3038-462: The image to a small sensor. More modern cameras no longer use this method; the simplification helps reduce cost. Uncooled technology available in many Enhanced Flight Vision System (EFVS or EVS) products have reduced the costs to fractions of the price of older cooled technology, with similar performance. EVS is rapidly becoming mainstream on many fixed wing and rotary wing operators from Cirrus and Cessna aircraft to large business jets. In 2001,

3100-531: The like. Pushbroom systems typically have been used on aircraft and satellites. Sideways-tracking imagers normally involve a one-dimensional (1D) array of pixels, which uses the motion of the aircraft or satellite to move the view of the 1D array across the ground to build up a 2D image over time. Such systems cannot be used for real-time imaging and must look perpendicular to the direction of travel. In 1956, Texas Instruments began research on infrared technology that led to several line scanner contracts and, with

3162-403: The manufacturing process. To remedy this, the response of each pixel is measured at the factory, and a transform, most often linear, maps the measured input signal to an output level. Some companies offer advanced "fusion" technologies that blend a visible-spectrum image with an infrared-spectrum image to produce better results than a single-spectrum image alone. Thermal imaging cameras such as

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3224-547: The market. In 2015, Northrop Grumman introduced its OpenPod IRST pod, which uses a sensor by Leonardo . The United States Air Force is currently incorporating IRST systems for its fighter aircraft fleet, including the F-15, F-16, and F-22. While IRST systems are most common amongst aircraft, land-based, ship and submarine systems are available. The F-35 is equipped with infrared search and track system AN/AAQ-37 Distributed Aperture System (DAS), which consists of six IR sensors around

3286-412: The mass of the gas exiting the nozzle. A jet engine can produce more thrust by either accelerating the gas to a higher velocity or ejecting a greater mass of gas from the engine. Designing a basic turbojet engine around the second principle produces the turbofan engine, which creates slower gas, but more of it. Turbofans are highly fuel efficient and can deliver high thrust for long periods of time, but

3348-551: The oxygen delivered by the compressor stages would create temperatures (3,700 °F (2,040 °C)) high enough to significantly weaken the internal structure of the engine, but by mixing the combustion products with unburned air from the compressor at (600 °F (316 °C)) a substantial amount of oxygen ( fuel/air ratio 0.014 compared to a no-oxygen-remaining value 0.0687) is still available for burning large quantities of fuel (25,000 lb/h (11,000 kg/h)) in an afterburner. The gas temperature decreases as it passes through

3410-591: The publication of the paper "Theoretical Investigation of Thrust Augmentation of Turbojet Engines by Tail-pipe Burning" in January 1947. American work on afterburners in 1948 resulted in installations on early straight-wing jets such as the Pirate , Starfire and Scorpion . The new Pratt & Whitney J48 turbojet, at 8,000 lbf (36 kN) thrust with afterburners, would power the Grumman swept-wing fighter F9F-6 , which

3472-405: The range. The best known modern IRST systems are: Fighter aircraft carry the IRST systems for use instead of radar when the situation warrants it, such as when shadowing other aircraft, under the control of airborne early warning and control (AWACS) aircraft, or executing a ground-controlled interception (GCI), where an external radar is used to help vector the fighter to a target and the IRST

3534-526: The same manner as the Rolls-Royce Pegasus , and fuel was burned in the fan air before it left the front nozzles. It would have given greater thrust for take-off and supersonic performance in an aircraft similar to, but bigger than, the Hawker Siddeley Harrier . Duct heating was used by Pratt & Whitney for their JTF17 turbofan proposal for the U.S. Supersonic Transport Program in 1964 and

3596-465: The turbine (to 1,013 °F (545 °C)). The afterburner combustor reheats the gas, but to a much higher temperature (2,540 °F (1,390 °C)) than the TET (1,570 °F (850 °C)). As a result of the temperature rise in the afterburner combustor, the gas is accelerated, firstly by the heat addition, known as Rayleigh flow , then by the nozzle to a higher exit velocity than that which occurs without

3658-580: Was about to go into production. Other new Navy fighters with afterburners included the Chance Vought F7U-3 Cutlass , powered by two 6,000 lbf (27 kN) thrust Westinghouse J46 engines. In the 1950s, several large afterburning engines were developed, such as the Orenda Iroquois and the British de Havilland Gyron and Rolls-Royce Avon RB.146 variants. The Avon and its variants powered

3720-420: Was considered to be of limited utility, and with the introduction of more automated radars they disappeared from fighter designs for some time. Detection range varies with external factors such as The higher the altitude, the less dense the atmosphere and the less infrared radiation it absorbs - especially at longer wavelengths. The effect of reduction in friction between air and aircraft does not compensate for

3782-408: Was refueled in-flight as part of every reconnaissance mission. An afterburner has a limited life to match its intermittent use. The J58 was an exception with a continuous rating. This was achieved with thermal barrier coatings on the liner and flame holders and by cooling the liner and nozzle with compressor bleed air instead of turbine exhaust gas. In heat engines such as jet engines, efficiency

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3844-405: Was similar to the later Texas Instruments AN/AAA-4 installed on early F-4 Phantoms . The F-4 Phantom had a Texas Instruments AAA-4 infrared seeker under the nose of early production aircraft F-4Bs and F-4Cs. It was not not installed on later F-4Ds due to limited capabilities, but retained the bulge and indeed some F-4Ds had the IRST receiver retrofitted in a modified form. The F-4E eliminated

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