4th generation jet fighter
Encyclopedia
Aircraft classified by the United States government as fourth-generation jet fighters
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...

are those in service approximately from 1980 to 2010, representing the design concepts of the 1970s.

Fourth-generation designs are heavily influenced by lessons learned from the previous generation of combat aircraft. Long-range air-to-air missile
Air-to-air missile
An air-to-air missile is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled...

s, originally thought to make dogfight
Dogfight
A dogfight, or dog fight, is a form of aerial combat between fighter aircraft; in particular, combat of maneuver at short range, where each side is aware of the other's presence. Dogfighting first appeared during World War I, shortly after the invention of the airplane...

ing obsolete, proved less influential than expected precipitating a renewed emphasis on maneuverability. Meanwhile, the growing costs of military aircraft in general and the demonstrated success of aircraft such as the F-4 Phantom II
F-4 Phantom II
The McDonnell Douglas F-4 Phantom II is a tandem two-seat, twin-engined, all-weather, long-range supersonic jet interceptor fighter/fighter-bomber originally developed for the United States Navy by McDonnell Aircraft. It first entered service in 1960 with the U.S. Navy. Proving highly adaptable,...

 gave rise to the popularity of multirole fighters in parallel with the advances marking the so-called fourth generation.

During the period in question, maneuverability was enhanced by relaxed static stability, made possible by introduction of the fly-by-wire
Fly-by-wire
Fly-by-wire is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires , and flight control computers determine how to move the actuators at each control...

 (FBW) flight control system
Aircraft flight control systems
A conventional fixed-wing aircraft flight control system consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight...

 (FLCS), which in turn was possible due to advances in digital computers and system integration techniques. Analog avionics, required to enable FBW operations, became a fundamental requirement and began to be replaced by digital flight control systems in the latter half of the 1980s.

The further advance of microcomputers in the 1980s and 1990s permitted rapid upgrades to the avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...

 over the lifetimes of these fighters, incorporating system upgrades such as AESA
Active Electronically Scanned Array
An Active Electronically Scanned Array , also known as active phased array radar is a type of phased array radar whose transmitter and receiver functions are composed of numerous small solid-state transmit/receive modules . AESAs aim their "beam" by broadcasting radio energy that interfere...

, digital avionics buses and IRST
Infra-red search and track
An infra-red search and track system is a method for detecting and tracking objects which give off infra-red radiation such as jet aircraft and helicopters. IRST is a generalized case of Forward Looking Infra-Red , i.e. from Forward-Looking to allround situational awareness...

. Due to the dramatic enhancement of capabilities in these upgraded fighters and in new designs of the 1990s that reflected these new capabilities, the US government has taken to using the designation 4.5th generation to refer to these later designs. This is intended to reflect a class of fighters that are evolutionary upgrades of the 4th generation incorporating integrated avionics suites, advanced weapons efforts to make the (mostly) conventionally designed aircraft nonetheless less easily detectable, and trackable as a response to advancing missile and RADAR
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 technology, see stealth technology
Stealth technology
Stealth technology also termed LO technology is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, and missiles, to make them less visible to radar, infrared, sonar and other detection...

. Inherent airframe design features exist, and include masking of turbine-blades and application of advanced sometimes radar-absorbent materials, but not the distinctive low-observable configurations of the latest aircraft, dubbed fifth-generation fighters or craft such as the F-117 and B-2.

The United States Government defines 4.5 generation fighter aircraft as fourth generation jet fighters that have been upgraded with AESA radar, high capacity data-link, enhanced avionics, and "the ability to deploy current and reasonably foreseeable advanced armaments."

Performance

General performance has traditionally been the most important class of design characteristics, as it enables a fighter to gain a favorable position to use its weapons while rendering the enemy unable to use theirs. This can occur at long range (beyond visual range or BVR) or short range (within visual range or WVR). At short range, the ideal position is to the rear of the enemy aircraft, where it is unable to aim or fire weapons and the hot exhaust makes a good target for infrared-guided missiles. At longer BVR range, the probability of a successful missile intercept is improved by launch at high energy, kinetic (the aircraft's speed towards its target) and potential (altitude advantage). Being able to maneuver violently, and without losing energy meanwhile increases the chance of evading enemy missiles, or escape out of range of the likely return-fire.

These two scenarios have competing demands — interception requires excellent linear speed, while Within Visual Range or WVR engagements require excellent turn rate, while maintaining speed, rapid acceleration, and availability of control at low-speeds and high angle of attack
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...

.

Prior to the 1970s, a popular view in the defense community was that missiles would render WVR combat obsolete and hence maneuverability useless. Combat experience proved this untrue due to the poor quality of missiles and the recurring need to identify targets visually. Though improvements in missile technology may make that vision a reality, experience has indicated that sensors are not foolproof and that fighters will still need to be able to fight and maneuver at close ranges. So whereas the premier third-generation jet fighters (e.g., the F-4
F-4 Phantom II
The McDonnell Douglas F-4 Phantom II is a tandem two-seat, twin-engined, all-weather, long-range supersonic jet interceptor fighter/fighter-bomber originally developed for the United States Navy by McDonnell Aircraft. It first entered service in 1960 with the U.S. Navy. Proving highly adaptable,...

 and MiG-23
Mikoyan-Gurevich MiG-23
The Mikoyan-Gurevich MiG-23 is a variable-geometry fighter aircraft, designed by the Mikoyan-Gurevich design bureau in the Soviet Union. It is considered to belong to the Soviet third generation jet fighter category, along with similarly aged Soviet fighters such as the MiG-25 "Foxbat"...

) were designed as interceptors with only a secondary emphasis on maneuverability, interceptors have been relegated to a secondary role in the fourth generation, with a renewed emphasis on maneuverability. While the trade-offs involved in combat aircraft design are again shifting towards BVR engagement, the management of the advancing environment of numerous information flows in the modern battle-space, and low-observability, arguably at the expense of maneuvering ability in close-combat, the application of thrust vectoring
Thrust vectoring
Thrust vectoring, also thrust vector control or TVC, is the ability of an aircraft, rocket or other vehicle to manipulate the direction of the thrust from its engine or motor in order to control the attitude or angular velocity of the vehicle....

 provides a way to maintain it, especially at low speed.

There are two primary contributing factors to maneuverability — the amount of thrust delivered by the engines, and the ability of the aircraft's control surfaces to efficiently generate aerodynamic forces, and hence alterations in the plane's direction. Air-combat maneuvering (ACM) involves a great deal of energy management. The greater energy a fighter has, the more flexibility it has to move where it wants. An aircraft with little energy is immobile, and becomes a defenseless target. Note that available thrust does not necessarily equal speed; while it does give greater acceleration, the maximum speed of an aircraft is also determined by how much drag it produces. Herein lies one important trade-off. Low-drag configurations have small, often highly swept wings that disrupt the airflow as little as possible. However, that also means they have greatly reduced ability to alter the airflow to maneuver the aircraft.

There are two rough indicators of these factors. A plane's turning ability can be roughly measured by its wing loading, defined as the mass of the aircraft divided by the area of its lifting surfaces. A highly loaded wing has little capacity to produce additional lift, and so has limited turning ability, whereas a lightly loaded wing has much greater potential lifting power. A rough measure of acceleration is a plane's thrust-to-weight ratio
Thrust-to-weight ratio
Thrust-to-weight ratio is a ratio of thrust to weight of a rocket, jet engine, propeller engine, or a vehicle propelled by such an engine. It is a dimensionless quantity and is an indicator of the performance of the engine or vehicle....

.

Fly-by-wire

The fourth generation jet fighter defining point is fly-by-wire
Fly-by-wire
Fly-by-wire is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires , and flight control computers determine how to move the actuators at each control...

, like 4.5 is defined on AESA radar. YF-16 was the world’s first aircraft intentionally designed to be slightly aerodynamically unstable. This technique, called "relaxed static stability" (RSS), was incorporated to further enhance the aircraft’s performance. Most aircraft are designed with positive static stability, which induces an aircraft to return to its original attitude following a disturbance. However, positive static stability; the tendency to remain in its current attitude; opposes the pilot’s efforts to maneuver. On the other hand, an aircraft with negative static stability will, in the absence of control input, readily deviate from level and controlled flight.

An aircraft with negative static stability can therefore be made more maneuverable. At supersonic airspeed, a negatively stable aircraft can exhibit positive static stability due to aerodynamic center migration. To counter this tendency to depart from controlled flight—and avoid the need for constant minute trimming inputs by the pilot—the 4th gen aircraft has a quadruplex (four-channel) fly-by-wire (FBW) flight control system
Aircraft flight control systems
A conventional fixed-wing aircraft flight control system consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight...

 (FLCS). The flight control computer (FLCC), which is the key component of the FLCS, accepts the pilot’s input from the stick and rudder controls, and manipulates the control surfaces in such a way as to produce the desired result without inducing a loss of control. The FLCC also takes thousands of measurements per second of the aircraft’s attitude, and automatically makes corrections to counter deviations from the flight path that were not input by the pilot, coordinated turn is also obtained in such a way that it updates itself by thousands of instructions and produces the required control thereby allowing for stable flight.

Thrust vectoring

Thrust vectoring
Thrust vectoring
Thrust vectoring, also thrust vector control or TVC, is the ability of an aircraft, rocket or other vehicle to manipulate the direction of the thrust from its engine or motor in order to control the attitude or angular velocity of the vehicle....

 is a new technology being introduced to further enhance a fighter's turning ability. By redirecting the jet exhaust, it is possible to directly translate the engine's power into directional changes more efficiently than via the plane's control surfaces. The Sukhoi Su-30 MKI, produced by India under license at Hindustan Aeronautics Limited
Hindustan Aeronautics Limited
Hindustan Aeronautics Limited based in Bangalore, India, is one of Asia's largest aerospace companies. Under the management of the Indian Ministry of Defence, this state-owned company is mainly involved in aerospace industry, which includes manufacturing and assembling aircraft, navigation and...

 is in active service with the Indian Air Force
Indian Air Force
The Indian Air Force is the air arm of the Indian armed forces. Its primary responsibility is to secure Indian airspace and to conduct aerial warfare during a conflict...

, and employs 2D thrust vectoring. The 2D TVC makes the aircraft highly maneuverable, capable of near-zero airspeed at high angles of attack without stalling, and dynamic aerobatics at low speeds. The TVC nozzles of the MKI are mounted 32 degrees outward to longitudinal engine axis (i.e. in the horizontal plane) and can be deflected ±15 degrees in the vertical plane. This produces a corkscrew
Corkscrew
A corkscrew is a kitchen tool for drawing stopping corks from wine bottles. Generally, a corkscrew consists of a pointed metallic helix attached to a handle. The user grips the handle and screws the metal point into the cork, until the helix is firmly embedded, then a vertical pull on the...

 effect, greatly enhancing the turning capability of the aircraft. The MiG-35 with its RD-33OVT engines with the vectored thrust nozzles allows it to be the first twin-engine aircraft with vectoring nozzles that can move in two directions that is 3D TVC. Other existing thrust vectoring aircraft, like the Su-30MKI and the F-22
F-22 Raptor
The Lockheed Martin/Boeing F-22 Raptor is a single-seat, twin-engine fifth-generation supermaneuverable fighter aircraft that uses stealth technology. It was designed primarily as an air superiority fighter, but has additional capabilities that include ground attack, electronic warfare, and signals...

, have nozzles that vector in one direction. The technology has been fitted to the Sukhoi
Sukhoi
Sukhoi Company is a major Russian aircraft manufacturer, headquartered in Begovoy District, Northern Administrative Okrug, Moscow, famous for its fighters...

 Su-47 Berkut
Sukhoi Su-47
The Sukhoi Su-47 Berkut , also designated S-32 and S-37 during initial development, was an experimental supersonic jet fighter developed by Sukhoi Aviation Corporation...

 and later derivatives. The U.S. explored fitting the technology to the F-16 and the F-15
F-15S/MTD
|-F-15 ACTIVE:-See also:- External links :* * *...

, but only introduced it on the F-22 Raptor
F-22 Raptor
The Lockheed Martin/Boeing F-22 Raptor is a single-seat, twin-engine fifth-generation supermaneuverable fighter aircraft that uses stealth technology. It was designed primarily as an air superiority fighter, but has additional capabilities that include ground attack, electronic warfare, and signals...

.

Supercruise

Supercruise
Supercruise
Supercruise is sustained supersonic flight of an aircraft with a useful cargo, passenger, or weapons load performed efficiently and without the use of afterburners ....

 is the ability of aircraft to cruise at supersonic speeds without the afterburner.

Because of parasitic drag effects, fighters carrying external weapons stores encounter a vastly increased drag-divergence near the speed of sound. This can prevent safe acceleration through the transonic
Transonic
Transonic speed is an aeronautics term referring to the condition of flight in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil that are concurrently below, at, and above the speed of sound in the range of Mach 0.8 to 1.2, i.e. 600–900 mph...

 regime, or make it too fuel-expensive to be effective on missions. Meanwhile, maintaining supersonic speed without (periodic) afterburner use saves large quantities of fuel too, increasing the range at which an aircraft can in reality still take advantage of its full performance.

According to the German Luftwaffe
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....

 the Typhoon
Eurofighter Typhoon
The Eurofighter Typhoon is a twin-engine, canard-delta wing, multirole combat aircraft, designed and built by a consortium of three companies: EADS, Alenia Aeronautica and BAE Systems; working through a holding company, Eurofighter GmbH, which was formed in 1986...

 can cruise at about Mach 1.2 without afterburner. The manufacturer claims that the maximum level speed possible without reheat is Mach 1.5. A EF T1 DA
Eurofighter Typhoon
The Eurofighter Typhoon is a twin-engine, canard-delta wing, multirole combat aircraft, designed and built by a consortium of three companies: EADS, Alenia Aeronautica and BAE Systems; working through a holding company, Eurofighter GmbH, which was formed in 1986...

 (Development Aircraft trainer version) demonstrate supercuise (1,21M) with 2 SRAAM, 4 MRAAM and drop tank (plus one tonne flight test equipment, plus 700 kg more weight for the trainer version) during the Singapore evaluation.

The Dassault Rafale
Dassault Rafale
The Dassault Rafale is a French twin-engine delta-wing multi-role jet fighter aircraft designed and built by Dassault Aviation. Introduced in 2000, the Rafale is being produced both for land-based use with the French Air Force and for carrier-based operations with the French Navy...

 can supercruise, in dry power, even with four missiles and a 1,250-liter belly drop tank and even in the naval version (Rafale M).

Avionics

Avionics is a catch-all term for the electronic systems aboard an aircraft, which have been growing in complexity and importance. The main elements of an aircraft's avionics are its communication and navigation systems, sensors (Radar and IR), computers and data bus, and user interface. Because they can be readily swapped out as new technologies become available, they are often upgraded over the lifetime of an aircraft. Details about these systems are highly classified. Thus, many export aircraft have downgraded avionics, and buyers often replace them with domestically developed avionics, sometimes considered superior to the original. Examples are the Sukhoi Su-30MKI sold to India, the F-15I
F-15 Eagle
The McDonnell Douglas F-15 Eagle is a twin-engine, all-weather tactical fighter designed by McDonnell Douglas to gain and maintain air superiority in aerial combat. It is considered among the most successful modern fighters with over 100 aerial combat victories with no losses in dogfights...

 and F-16I
F-16 Fighting Falcon
The General Dynamics F-16 Fighting Falcon is a multirole jet fighter aircraft originally developed by General Dynamics for the United States Air Force . Designed as an air superiority day fighter, it evolved into a successful all-weather multirole aircraft. Over 4,400 aircraft have been built since...

 sold to Israel, and the F-15K
F-15E Strike Eagle
The McDonnell Douglas F-15E Strike Eagle is an all-weather multirole fighter, derived from the McDonnell Douglas F-15 Eagle. The F-15E was designed in the 1980s for long-range, high speed interdiction without relying on escort or electronic warfare aircraft. United States Air Force F-15E Strike...

 sold to South Korea.
The primary sensor for all modern fighters is radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

. The U.S. fielded its first modified F-15Cs equipped with APG-63(V)2 AESA radars, which have no moving parts and are capable of projecting a much tighter beam and quicker scans. Later on, it was introduced to the F/A-18E/F Super Hornet
F/A-18E/F Super Hornet
The Boeing F/A-18E/F Super Hornet is a twin-engine carrier-based multirole fighter aircraft. The F/A-18E single-seat variant and F/A-18F tandem-seat variant are larger and more advanced derivatives of the F/A-18C and D Hornet. The Super Hornet has an internal 20 mm gun and can carry air-to-air...

 and the block 60 (export) F-16 also, and will be used for future American fighters. A European coalition GTDAR
GTDAR
GTDAR is a European consortium for the development of the AMSAR Active Electronically Scanned Array.This organisation was named after the original partners, and is now made up of their successor companies, BAE Systems, Thales, and EADS, respectively....

 is developing an AESA radar for use on the Typhoon and Rafale, and Russia has an AESA radar on its MIG-35 and their newest Su-27
Sukhoi Su-27
The Sukhoi Su-27 is a twin-engine supermanoeuverable fighter aircraft designed by Sukhoi. It was intended as a direct competitor for the large United States fourth generation fighters, with range, heavy armament, sophisticated avionics and high manoeuvrability...

 versions. For the next-generation F-22 and F-35, the U.S. will use Low Probability of Intercept
Low probability of intercept
A low-probability-of-intercept radar is designed to be difficult to detect by passive radar detection equipment while it is searching for a target or engaged in target tracking...

 (LPI) capacity. This will spread the energy of a radar pulse over several frequencies, so as not to trip the radar warning receivers that all aircraft carry.
In response to the increasing American emphasis on radar-evading stealth designs, Russia turned to alternate sensors, with emphasis on infra-red search and track
Infra-red search and track
An infra-red search and track system is a method for detecting and tracking objects which give off infra-red radiation such as jet aircraft and helicopters. IRST is a generalized case of Forward Looking Infra-Red , i.e. from Forward-Looking to allround situational awareness...

 (IRST) sensors, first introduced on the American F-101 Voodoo
F-101 Voodoo
The McDonnell F-101 Voodoo was a supersonic military jet fighter which served the United States Air Force and the Royal Canadian Air Force...

 and F-102 Delta Dagger
F-102 Delta Dagger
The Convair F-102 Delta Dagger was a US interceptor aircraft built as part of the backbone of the United States Air Force's air defenses in the late 1950s. Entering service in 1956, its main purpose was to intercept invading Soviet bomber fleets...

 fighters in the 1960s, for detection and tracking of airborne targets. These measure IR radiation from targets. As a passive sensor, it has limited range, and contains no inherent data about position and direction of targets - these must be inferred from the images captured. To offset this, IRST systems can incorporate a laser rangefinder in order to provide full fire-control solutions for cannon fire or got launching missiles. Using this method, German MiG-29 using helmet-displayed IRST systems were able to acquire a missile lock with greater efficiency than USAF F-16 in wargame exercises. IRST sensors have now become standard on Russian aircraft. With the exception of the F-14D
F-14 Tomcat
The Grumman F-14 Tomcat is a supersonic, twin-engine, two-seat, variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experimental program following the collapse of the F-111B project...

 (officially retired as of September 2006), no 4th-generation Western fighters carry built-in IRST sensors for air-to-air detection, though the similar FLIR is often used to acquire ground targets.

The Eurofighter Typhoon designated '4.5th generation' (beginning with Tranche 1 Block 5 aircraft, while previously build aircraft are being retrofited since spring 2007) and the F-35s will have built-in, PIRATE IRST sensors, a feature adopted early in the design, meanwhile beginning in 2012 the Super Hornet will also have an IRST.

The tactical implications of the computing and data bus capabilities of aircraft are hard to determine. A more sophisticated computer bus would allow more flexible uses of the existing avionics. For example, it is speculated that the F-22 is able to jam or damage enemy electronics with a focused application of its radar. A computing feature of significant tactical importance is the datalink. All modern European and American aircraft are capable of sharing targeting data with allied fighters and AWACS planes (see JTIDS). The Russian MiG-31 interceptor also has some datalink capability, so it is reasonable to assume that other Russian planes can also do so. The sharing of targeting and sensor data allows pilots to put radiating, highly visible sensors further from enemy forces, while using that data to vector silent fighters toward the enemy.

Stealth technology

Stealth technology
Stealth technology
Stealth technology also termed LO technology is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, and missiles, to make them less visible to radar, infrared, sonar and other detection...

 is an extension of the notion of visual camouflage to modern radar and IR detection sensors. While not rendering an aircraft "invisible" as is popularly conceived, stealth makes an aircraft much more difficult to discern among the sky, clouds, or distant aircraft, conferring a significant tactical advantage. While the basic principles of shaping aircraft to avoid detection were known at least since the 1960s, it was not until the availability of supercomputers that shape computations could be performed from every angle, a complex task. The use of computer-aided shaping, combined with radar-absorbent materials, produced aircraft of drastically reduced radar cross section (RCS
Radar cross section
Radar cross section is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected.An object reflects a limited amount of radar energy...

) that were much more difficult to detect on radar. Meanwhile advances in digital flight control make potentially destabilizing, or control-complicating effects of shape alterations easier to compensate for.

During the 1970s, the rudimentary level of stealth shaping (as seen in the faceted design of the F-117 Nighthawk
F-117 Nighthawk
The Lockheed F-117 Nighthawk was a single-seat, twin-engine stealth ground-attack aircraft formerly operated by the United States Air Force . The F-117A's first flight was in 1981, and it achieved initial operating capability status in October 1983...

) resulted in too severe a performance penalty to be used on fighters. Faster computers enabled smoother designs such as the B-2 Spirit
B-2 Spirit
The Northrop Grumman B-2 Spirit is an American heavy bomber with low observable stealth technology designed to penetrate dense anti-aircraft defenses and deploy both conventional and nuclear weapons. The bomber has a crew of two and can drop up to eighty -class JDAM GPS-guided bombs, or sixteen ...

, and thought was given to applying the basic ideas to decrease, if not drastically reduce, the RCS of fighter aircraft. These techniques are also combined with methods of decreasing the IR, visual, and aural signature of the aircraft. While fighters designated 4.5th generation under the US-devised system incorporate some low-observable features, so-called fifth generation fighters have more clearly been designed with this as a very high priority. The inclusion of this as a criterion for the designation of "fifth generation" serves to illustrate the degree to which US manufacturers and their clients appear to assign value to this capability.

There are some reports that the Dassault Rafale
Dassault Rafale
The Dassault Rafale is a French twin-engine delta-wing multi-role jet fighter aircraft designed and built by Dassault Aviation. Introduced in 2000, the Rafale is being produced both for land-based use with the French Air Force and for carrier-based operations with the French Navy...

's avionics, the Thales Spectra
Thales Spectra
The Thales SPECTRA is an integrated defensive aids suite developed by Thales Group for the Dassault Rafale series of fighter aircraft.All elements of the Thales SPECTRA system are built into the airframe, and have high levels of automation and system...

, includes "stealthy" radar jamming technology, and systems for the active cancellation of RADAR analogous to the acoustic noise suppression systems on the De Havilland Canada Dash 8. Conventional jammers make locating an aircraft more difficult, but their operation is itself detectable, with missiles being designed more recently to endeavor to follow the jamming itself. The French system is hypothesized to interfere with detection without revealing that jamming is in operation.

Such a system ought in principle to be able to make an aircraft entirely invisible, were it to be feasible to actively mimic an undisturbed RADAR signature (canceling all reflections, and compensating for any RADAR shadow) however such a system would be incalculably difficult and is not envisaged. Meanwhile the real effectiveness of systems that allegedly exist is unknown.

Research continues into other ways of decreasing observability by radar. There are claims that Russian researchers are working on "plasma stealth
Plasma stealth
Plasma stealth is a proposed process to use ionized gas to reduce the radar cross section of an aircraft. Interactions between electromagnetic radiation and ionized gas have been extensively studied for many purposes, including concealing aircraft from radar as stealth technology...

". Obviously, such techniques might well remove some of the envisaged advantages held by fifth generation aircraft, adding to skepticism over the real value of the "generation" label, which seems to assume the superiority and uniqueness of particular design philosophies. An aircraft with no stealth features, but some advanced ability to detect "stealth" for example, may not "qualify" and yet hold equal advantages to current US aircraft. As yet no such capability has been demonstrated however.

There are in any case ways to detect fighters other than radar. For instance, passive infra-red sensors can detect the heat of engines, and even the sound of a sonic boom
Sonic boom
A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...

 (which any supersonic aircraft will make) can be tracked with a network of sensors and computers. However, using these to provide precise targeting information for a long-range missile is considerably less straightforward than radar.

Combat performance

The F-15 and F-16 have the first and second best known overall combat records of modern jet fighters. F-15s have a claimed combat record of 101 victories and zero losses in actual air to air combat. Naturally such statistics take no account of the quality of the opposition, and are of limited use in comparing aircraft that have not been sent on identical missions, much less against one another.
  • 1982 Lebanon War
    1982 Lebanon War
    The 1982 Lebanon War , , called Operation Peace for Galilee by Israel, and later known in Israel as the Lebanon War and First Lebanon War, began on 6 June 1982, when the Israel Defense Forces invaded southern Lebanon...

    , Israeli Air Force credited their F-15s and F-16s with 86 air-to-air kills, mostly of MiG-21s and MiG-23s, while suffering no air-to-air losses of their own.

  • 1979-1989 Soviet war in Afghanistan
    Soviet war in Afghanistan
    The Soviet war in Afghanistan was a nine-year conflict involving the Soviet Union, supporting the Marxist-Leninist government of the Democratic Republic of Afghanistan against the Afghan Mujahideen and foreign "Arab–Afghan" volunteers...

     Pakistan Air Force F-16s claimed 10 Air-Air Kills on Soviet aircraft of various types with no losses. This was achieved with no BVR armament available to the PAF while the Soviet Air Force routinely used BVR armed MIG-29s for air cover although not directly against the Pakistan Air Force.

  • Iran–Iraq War, saw the first instance of employing 4th generation jet fighters in open war. Iran used F-14s and Iraq deployed MiG-29s, although there are no reports of the two aircraft types actually engaging each other.

  • 1991 Gulf War
    Gulf War
    The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...

    • On 17 January 1991, the first night of the Gulf War, an Iraq
      Iraq
      Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....

      i MiG-25PD shot down a U.S. Navy F/A-18C (piloted by Lt Cdr Scott Speicher
      Scott Speicher
      Michael Scott Speicher was a United States Navy pilot who was shot down over Iraq during the Gulf War. He was the first American combat casualty of the conflict. His remains were not recovered until Aug. 2, 2009...

      ), which was lost 29 nautical miles (53.7 km) southeast of Baghdad
      Baghdad
      Baghdad is the capital of Iraq, as well as the coterminous Baghdad Governorate. The population of Baghdad in 2011 is approximately 7,216,040...

      .
    • USAF F-15
      F-15 Eagle
      The McDonnell Douglas F-15 Eagle is a twin-engine, all-weather tactical fighter designed by McDonnell Douglas to gain and maintain air superiority in aerial combat. It is considered among the most successful modern fighters with over 100 aerial combat victories with no losses in dogfights...

       pilots shot down five Iraq
      Iraq
      Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....

      i MiG-29s.

  • On 8 October 1996, after the escalation over Imia/Kardak a Greek
    Greece
    Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

     Mirage 2000 fired an R550 Magic
    R550 Magic
    The R.550 Magic is a short-range missile designed in 1968 by French company Matra to compete with the American AIM-9 Sidewinder. On 11 January 1972, a Gloster Meteor of the centre for in-flight trials fired the R550 Magic and shot down a Nord CT20 target drone .Mass-produced from 1976, the Magic...

     and shot down a Turkish F-16D over the Aegean Sea. The Turkish pilot died, while the co-pilot ejected and was rescued by Greek forces.

  • During the Kargil Conflict between India and Pakistan in year 1999, the Indian Air Force used Dessault Mirrage 2000s to drop laser guided bombs. MiG-29s were used extensively to provide fighter escort to the Mirage 2000s. The Mirages successfully targeted Pakistani camps and logistic bases in Kargil. Two Mirage squadrons flew a total of 515 sorties, and in 240 strike missions dropped 55,000 kg (120,000 lb) of ordnance.

  • 1999 Kosovo War
    Kosovo War
    The term Kosovo War or Kosovo conflict was two sequential, and at times parallel, armed conflicts in Kosovo province, then part of FR Yugoslav Republic of Serbia; from early 1998 to 1999, there was an armed conflict initiated by the ethnic Albanian "Kosovo Liberation Army" , who sought independence...

    • A Dutch
      Royal Netherlands Air Force
      The Royal Netherlands Air Force , Dutch Koninklijke Luchtmacht , is the military aviation branch of the Netherlands Armed Forces. Its ancestor, the Luchtvaartafdeling of the Dutch Army was founded on 1 July 1913, with four pilots...

       F-16 pilot shot down a Yugoslavia
      Yugoslavia
      Yugoslavia refers to three political entities that existed successively on the western part of the Balkans during most of the 20th century....

      n MiG-29 and a USAF F-16 pilot also shot down a MiG-29.
    • USAF F-15 pilots shot down four MiG-29s.

  • Eritrean-Ethiopian War
    Eritrean-Ethiopian War
    The Eritrean–Ethiopian War took place from May 1998 to June 2000 between Ethiopia and Eritrea, forming one of the conflicts in the Horn of Africa...

    . In February 1999, according to some reports, Ethiopia
    Ethiopia
    Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...

    n Su-27 pilots shot down four Eritrea
    Eritrea
    Eritrea , officially the State of Eritrea, is a country in the Horn of Africa. Eritrea derives it's name from the Greek word Erethria, meaning 'red land'. The capital is Asmara. It is bordered by Sudan in the west, Ethiopia in the south, and Djibouti in the southeast...

    n MiG-29s. Some of these sources claim that the Ethiopian planes were flown by Russian pilots, and the Eritrean planes by Ukrainians. (It is certainly true that local pilots were trained by instructors from those nations.)

Exercise reports


Different air forces regularly practice against each other in exercises, and when they fly different aircraft some indication of the relative capabilities of the aircraft can be gained.
During the "Cope India '04" exercise (2004), USAF F-15 Eagles were pitted against Indian Air Force Su-30MKs, Mirage 2000s, MiG-29s and elderly MiG-21s. The results have been widely publicized, with the Indians winning "90% of the mock combat missions".
The "Cope India 2005" exercise was conducted with teams that used a combination of United States and Russian-designed aircraft. The Christian Science Monitor (CSM) reported that “both the Americans and the Indians won, and lost.” However, it also noted “that in a surprising number of encounters — particularly between the American F-16s and the Indian Sukhoi-30 MKIs — the Indian pilots came out the winners.

According to the same article the Indian air force designed Cope 2005 in that the rules of engagement be that the forces fight within visual range, and both forces could not take advantage of their long range sensors or weapons. The article goes on to state that a retired Indian Air Force General stated that: "The Sukhoi is a... better plane than the F-16." The USAF was said to be “most impressed by the MiG-21 Bisons and the Su-30 MKIs”.

In July 2007, the Indian Air Force fielded the MKI (Sukhoi Su-30MKI) during the Indra-Dhanush exercise with Royal Air Force's Eurofighter Typhoon
Eurofighter Typhoon
The Eurofighter Typhoon is a twin-engine, canard-delta wing, multirole combat aircraft, designed and built by a consortium of three companies: EADS, Alenia Aeronautica and BAE Systems; working through a holding company, Eurofighter GmbH, which was formed in 1986...

. This was the first time that the two jets had taken part in such a exercise. The IAF did not allow their pilots to use the radar of the MKIs during the exercise so as to protect the highly-classified N011M Bars. RAF Tornado pilots were candid in their admission of the Su-30MKI's superior manoeuvring in the air, just as they had anticipated, but the IAF pilots were also impressed by the Typhoon's agility in the air.

In June 2005, a Royal Air Force Eurofighter trainer two seater was reportedly able, in a mock confrontation, to avoid two pursuing F-15E fighter-bombers and outmaneuver them, to get into a shooting position. It is to be noted that despite the nomenclature that seems designed to lump these aircraft together, the RAF Typhoon aircraft has been designed in principle to supersede aircraft such as the F-15 which has been in service for some decades.

Aircraft

    • Dassault Mirage 2000/N/D
    • Dassault Rafale
      Dassault Rafale
      The Dassault Rafale is a French twin-engine delta-wing multi-role jet fighter aircraft designed and built by Dassault Aviation. Introduced in 2000, the Rafale is being produced both for land-based use with the French Air Force and for carrier-based operations with the French Navy...


    • HAL Tejas
      HAL Tejas
      The HAL Tejas is a lightweight multirole fighter developed by India. It is a tailless, compound delta-wing design powered by a single engine. It came from the Light Combat Aircraft programme, which began in the 1980s to replace India's ageing MiG-21 fighters...


    • HESA Saeqeh

    • IAI Kfir
      IAI Kfir
      The Israel Aircraft Industries Kfir is an Israeli-built all-weather, multirole combat aircraft based on a modified Dassault Mirage 5 airframe, with Israeli avionics and an Israeli-made version of the General Electric J79 turbojet engine.-Background:...

       (C.10 and C.12)

    • Chengdu J-10
      Chengdu J-10
      The Chengdu J-10 is a multirole fighter aircraft designed and produced by the People's Republic of China's Chengdu Aircraft Industry Corporation for the People's Liberation Army Air Force...

    • Shenyang J-11
      Shenyang J-11
      The Shenyang J-11 with NATO reporting name: Flanker B+ is a single-seat, twin-engine jet fighter based on the Soviet-designed Sukhoi Su-27 air superiority fighter produced by the Shenyang Aircraft Corporation...

    • Shenyang J-15
      Shenyang J-15
      - References :Citations*- External links :*, J-15 fighter photos and introductions, AirForceWorld.com...

       (navy)
    • Xian JH-7
      Xian JH-7
      The Xian JH-7 ; NATO reporting name Flounder), also known as the FBC-1 Flying Leopard, is a tandem two-seat, twin-engine fighter-bomber in service with the People's Liberation Army Naval Air Force , and the People's Liberation Army Air Force...


/
    • CAC
      Chengdu Aircraft Industry Group
      Chengdu Aircraft Industry Group is a Chinese aerospace conglomerate that manufactures aircraft parts as well as designs and manufactures combat aircraft. It was founded in 1958 to be a supplier of aircraft for the Chinese military...

       JF-17 Thunder
      JF-17 Thunder
      The PAC JF-17 Thunder , or CAC FC-1 Xiaolong , is a light-weight, single-engine, multi-role combat aircraft developed jointly by the Chengdu Aircraft Industries Corporation of China, the Pakistan Air Force and the Pakistan Aeronautical Complex...


/
    • AIDC F-CK-1 Ching-kuo

/
    • Sukhoi Su-30MKI
    • Mikoyan MiG-29K
      Mikoyan MiG-29K
      The Mikoyan MiG-29K is an all-weather carrier-based multirole fighter aircraft developed by the Mikoyan design bureau. The MiG-29K was developed in the late 1980s from MiG-29M....


-
    • Mikoyan MiG-29
      Mikoyan MiG-29
      The Mikoyan MiG-29 is a fourth-generation jet fighter aircraft designed in the Soviet Union for an air superiority role. Developed in the 1970s by the Mikoyan design bureau, it entered service with the Soviet Air Force in 1983, and remains in use by the Russian Air Force as well as in many other...

      /MiG-29M
      Mikoyan MiG-29M
      The Mikoyan MiG-29M is a mature development of the MiG-29M/M2 and MiG-29K/KUB technology. Formerly known as the "MiG-33", it was developed from the Mikoyan MiG-29 fighter jet during mid-1980s...

      /MiG-35
      Mikoyan MiG-35
      The Mikoyan MiG-35 is a further development of the MiG-29M/M2 and MiG-29K/KUB technology. It is classified as a 4++ generation jet fighter by Mikoyan. The first prototype was a modification of the aircraft that previously served as MiG-29M2 model demonstrator. 10 prototypes have been built so far...

    • Mikoyan MiG-29K
      Mikoyan MiG-29K
      The Mikoyan MiG-29K is an all-weather carrier-based multirole fighter aircraft developed by the Mikoyan design bureau. The MiG-29K was developed in the late 1980s from MiG-29M....

       (navy)
    • Mikoyan MiG-31
      Mikoyan MiG-31
      The Mikoyan MiG-31 is a supersonic interceptor aircraft developed to replace the MiG-25 "Foxbat". The MiG-31 was designed by the Mikoyan design bureau based on the MiG-25.-Development:...

    • Sukhoi Su-27
      Sukhoi Su-27
      The Sukhoi Su-27 is a twin-engine supermanoeuverable fighter aircraft designed by Sukhoi. It was intended as a direct competitor for the large United States fourth generation fighters, with range, heavy armament, sophisticated avionics and high manoeuvrability...

      /Su-30
      Sukhoi Su-30
      The Sukhoi Su-30 is a twin-engine, two-seat military aircraft developed by Russia's Sukhoi Aviation Corporation. It is a multirole fighter for all-weather, air-to-air and air-to-surface deep interdiction missions.The Su-30 started out as an internal development project in the Sukhoi Su-27 family...

      /Su-35
      Sukhoi Su-35
      The Sukhoi Su-35 is a single-seat, twin-engined supermaneuverability multirole fighter. It is a derivative of the Su-27 'Flanker', and was initially known as the Su-27M. More than a dozen of these were built with some used by the Russian Knights aerobatic demonstration team...

    • Sukhoi Su-33
      Sukhoi Su-33
      The Sukhoi Su-33 is an all-weather carrier-based air defence fighter designed by Sukhoi and manufactured by KnAAPO. It is a derivative of the Su-27 "Flanker" and was initially known as the Su-27K. The aircraft was first used in operations in 1995, aboard the carrier Admiral Kuznetsov...

       (navy)
    • Sukhoi Su-34
      Sukhoi Su-34
      The Sukhoi Su-34 is a Russian twin-seat fighter-bomber. It is intended to replace the Sukhoi Su-24.- Beginnings and testing :The Su-34 had a somewhat muddied and protracted beginning...


    • KAI FA-50 (maiden flight in 2012)

    • Saab JAS 39 Gripen

///
    • Eurofighter Typhoon
      Eurofighter Typhoon
      The Eurofighter Typhoon is a twin-engine, canard-delta wing, multirole combat aircraft, designed and built by a consortium of three companies: EADS, Alenia Aeronautica and BAE Systems; working through a holding company, Eurofighter GmbH, which was formed in 1986...


/
    • Panavia Tornado ADV
      Panavia Tornado ADV
      The Panavia Tornado Air Defence Variant is a long-range, twin-engine interceptor version of the swing-wing Panavia Tornado. The aircraft's first flight was on 27 October 1979, and it entered service in 1986. It was retired on 22 March 2011 by the Royal Air Forceand is now only in service with the...


    • General Dynamics
      General Dynamics
      General Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...

      /Lockheed Martin
      Lockheed Martin
      Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....

       F-16 Fighting Falcon
      F-16 Fighting Falcon
      The General Dynamics F-16 Fighting Falcon is a multirole jet fighter aircraft originally developed by General Dynamics for the United States Air Force . Designed as an air superiority day fighter, it evolved into a successful all-weather multirole aircraft. Over 4,400 aircraft have been built since...

    • Grumman F-14 Tomcat
      F-14 Tomcat
      The Grumman F-14 Tomcat is a supersonic, twin-engine, two-seat, variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experimental program following the collapse of the F-111B project...

       (navy)
    • McDonnell Douglas
      McDonnell Douglas
      McDonnell Douglas was a major American aerospace manufacturer and defense contractor, producing a number of famous commercial and military aircraft. It formed from a merger of McDonnell Aircraft and Douglas Aircraft in 1967. McDonnell Douglas was based at Lambert-St. Louis International Airport...

       F/A-18 Hornet
      F/A-18 Hornet
      The McDonnell Douglas F/A-18 Hornet is a supersonic, all-weather carrier-capable multirole fighter jet, designed to dogfight and attack ground targets . Designed by McDonnell Douglas and Northrop, the F/A-18 was derived from the latter's YF-17 in the 1970s for use by the United States Navy and...

      /F/A-18E/F Super Hornet (navy)
    • McDonnell Douglas
      McDonnell Douglas
      McDonnell Douglas was a major American aerospace manufacturer and defense contractor, producing a number of famous commercial and military aircraft. It formed from a merger of McDonnell Aircraft and Douglas Aircraft in 1967. McDonnell Douglas was based at Lambert-St. Louis International Airport...

      /Boeing
      Boeing
      The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...

       F-15 Eagle
      F-15 Eagle
      The McDonnell Douglas F-15 Eagle is a twin-engine, all-weather tactical fighter designed by McDonnell Douglas to gain and maintain air superiority in aerial combat. It is considered among the most successful modern fighters with over 100 aerial combat victories with no losses in dogfights...

      /F-15E Strike Eagle
      F-15E Strike Eagle
      The McDonnell Douglas F-15E Strike Eagle is an all-weather multirole fighter, derived from the McDonnell Douglas F-15 Eagle. The F-15E was designed in the 1980s for long-range, high speed interdiction without relying on escort or electronic warfare aircraft. United States Air Force F-15E Strike...

      /F-15SE Silent Eagle/
    • Mitsubishi F-2
      Mitsubishi F-2
      The Mitsubishi F-2 is a multirole fighter manufactured by Mitsubishi Heavy Industries and Lockheed Martin for the Japan Air Self-Defense Force, with a 60/40 split in manufacturing between Japan and the USA. Production started in 1996 and the first aircraft entered service in 2000. The first 76...


Canceled aircraft

    • FMA SAIA 90
      FMA SAIA 90
      The FMA SAIA 90 was an air superiority aircraft designed by the FMA with the collaboration of Dornier in the mid-1980s...

       (never built)


    • IAI Lavi
      IAI Lavi
      The IAI Lavi was a combat aircraft developed in Israel in the 1980s. It was a multi-billion dollar fighter aircraft project that was disbanded when the Israeli government concluded it could not finance production on its own, could not achieve a consensus on the Lavi's cost-effectiveness and...

       (maiden flight on 31 December 1986)
    • IAI Nammer (maiden flight on 21 March 1991)


    • IAR 95
      IAR 95
      -See also:-References:* * International Air Power Review, Winter 2001-2002-External links:* Romanian Supersonic Projects...

       (never built)

    • Atlas Carver
      Atlas Carver
      The Atlas Carver was a project launched in the 1980s by the South African Atlas Aircraft Corporation to replace the aging Canberra, Buccaneer, and Mirage III in the South African Air Force...

       (never built)

-
    • M-ATF
      M-ATF
      -References:* http://www.acig.org/artman/publish/article_490.shtml...

       (never built)
    • Mikoyan Project 1.44
      Mikoyan Project 1.44
      The Mikoyan Project 1.44/1.42 was a technology demonstrator developed by Mikoyan. It was the Soviet Union's answer to the Advanced Tactical Fighter of the US, incorporating numerous fifth-generation fighter aspects such as advanced avionics, stealth, supermaneuoverability and supercruise...

       (technology demonstrator)
    • Sukhoi Su-47
      Sukhoi Su-47
      The Sukhoi Su-47 Berkut , also designated S-32 and S-37 during initial development, was an experimental supersonic jet fighter developed by Sukhoi Aviation Corporation...

       (maiden flight on 25 September 1997) (technology demonstrator)
    • Yakovlev Yak-141
      Yakovlev Yak-141
      The Yakovlev Yak-141 , also known as the Yak-41, is a supersonic vertical takeoff/landing fighter aircraft designed by Yakolev. It did not enter production.-Design and development:...

       (maiden flight on 9 March 1987)/Yak-43 (never built)
    • Yakovlev Yak-45
      Yakovlev Yak-45
      The Yakovlev Yak-45 as the designation for a series of design studies in 1973-1974 for a single seat fighter. It lost to the MiG-29.-History:...

       (never built)

    • British Aerospace EAP
      British Aerospace EAP
      -External links:*...

       (maiden flight on 8 August 1986) (technology demonstrator)

    • Northrop
      Northrop Corporation
      Northrop Corporation was a leading United States aircraft manufacturer from its formation in 1939 until its merger with Grumman to form Northrop Grumman in 1994. The company is known for its development of the flying wing design, although only a few of these have entered service.-History:Jack...

       YF-17 (maiden flight on 9 June 1974)
    • Northrop
      Northrop Corporation
      Northrop Corporation was a leading United States aircraft manufacturer from its formation in 1939 until its merger with Grumman to form Northrop Grumman in 1994. The company is known for its development of the flying wing design, although only a few of these have entered service.-History:Jack...

       F-20 Tigershark (maiden flight on 30 August 1982)

    • Novi Avion
      Novi Avion
      |-See also:-References:* Newspaper article on Novi Avion* Aerosvet Magazine* Jane's All the World's Aircraft...

       (never built)

See also

  • List of fighter aircraft
  • Third generation jet fighter
    Third generation jet fighter
    The third-generation jet fighters existed between the early 1960s to the 1970s.-Development:The third generation witnessed continued maturation of second-generation innovations, but it is most marked by renewed emphases on manoeuvrability and traditional ground-attack capabilities...

  • Fifth generation jet fighter
    Fifth generation jet fighter
    A fifth-generation jet fighter is a fighter aircraft classification used in the United States encompassing the most advanced generation of fighter aircraft...

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