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121-731: All information in this section adapted from MiG-21 (2008). Chinese-built variants of the MiG-21 are designated Chengdu J-7 and F-7 (for export). Only the initial version of the J-7 was a copy of a MiG-21 variant, namely the MiG-21F-13. Though an agreement had been reached between China and the USSR for licence production of the MiG-21 in China, political relations soured between the two countries, causing Soviet assistance to stop. The Chinese reverse-engineered parts of

242-554: A technology transference arrangement pertaining to the MiG-21. Allegedly, while various kits, components, completed aircraft and associated documents were delivered to the Shenyang Aircraft Factory , the design documentation was incomplete, and Chinese designers made efforts to reverse engineer the aircraft. While the two aircraft are greatly similar, areas of difference include the hydraulic systems and internal fuel arrangements. During March 1964, domestic production of

363-573: A Soviet gesture to make peace, while suspicious, they were nonetheless eager to take up the Soviet offer of an aircraft deal. A delegation headed by General Liu Yalou , the commander-in-chief of the People's Liberation Army Air Force (PLAAF) and himself a Soviet military academy graduate, was dispatched to Moscow immediately; the Chinese delegation was given three days to visit the MiG-21's production facility, which

484-610: A better weapon than the Falcon: B models managed a 14% kill ratio, while the much longer-ranged D models managed 19%. Its performance and lower cost led the Air Force to adopt it as well. The first heat-seeker built outside the US was the UK's de Havilland Firestreak . Development began as OR.1056 Red Hawk , but this was considered too advanced, and in 1951 an amended concept was released as OR.1117 and given

605-643: A further 220 were built from scratch by 1984. Despite a series of crashes during the 1990s, the Indian Air Force has decided to upgrade about 125 of the MiG-21bis in its inventory to the MiG-21UPG standard. Those can serve until 2025. The original MiG-21FL (MiG-21PF or Type 77) was retired in December 2013; remaining MiG-21Ms (Type 88) were scheduled to be retired by 2015. The engines used in MiG-21 variants are listed in

726-698: A ground radar. Two F-7s were sent to bomb two rebel airstrips in the Mullaitivu and Kilinochchi areas, while the third reportedly intercepted one Zlín-143. According to the Sri Lankan government, the rebel-flown aircraft was shot down by the chasing F-7G using an air-to-air missile, as it was returning to Mullaitivu after a bombing run against Vavuniya Airport . Data from Jane's All The World's Aircraft 2003–2004 General characteristics Performance Armament Avionics Related development Infrared homing Infrared homing

847-603: A large searchlight fitted with a filter to limit the output to the IR range. This provided enough light to see the target at short range, and Spanner Anlage was fitted to a small number of Messerschmitt Bf 110 and Dornier Do 17 night fighters . These proved largely useless in practice and the pilots complained that the target often only became visible at 200 metres (660 ft), at which point they would have seen it anyway. Only 15 were built and were removed as German airborne radar systems improved though 1942. AEG had been working with

968-511: A mid-air collision during a rehearsal of an aerial display for the 58th anniversary of Nigeria's independence. During the lengthy Second Sudanese Civil War , Sudan procured a number of F-7s. In November 1993, it was reported that Iran had allegedly financed Sudan's purchase of around 20 Chinese ground-attack aircraft, having pledged $ 17 million in financial aid to the Sudanese government and arranged for $ 300 million in Chinese arms to be delivered to

1089-462: A missile airframe and considerable effort remained before an actual weapon would be ready for use. Nevertheless, a summer 1944 report to the German Air Ministry stated that these devices were far better developed than competing systems based on radar or acoustic methods. Aware of the advantages of passive IR homing, the research program started with a number of theoretical studies considering

1210-511: A more conventional hemispherical dome. The first test firing took place in 1955 and it entered service with the Royal Air Force in August 1958. The French R.510 project began later than Firestreak and entered experimental service in 1957, but was quickly replaced by a radar-homing version, the R.511. Neither was very effective and had short range on the order of 3 km. Both were replaced by

1331-499: A more stable center of gravity, and therefore better Longitudinal static stability . The cockpit was also revised to replace the Soviet ejection seat, which was deemed to be unacceptable. The forward opening canopy was replaced by a standard rear-hinged canopy, which was jettisoned prior to ejection. The re-engineering effort was largely successful, as the Chinese-built J-7 showed only minor differences in design and performance from

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1452-420: A multipurpose display. Many of the electronic components were British in origin, such as the gun sight and the multi purpose display. The aircraft is capable of using PL-8/Python 3 missiles with both the helmet mounted sight or the radar fire control, but the two are not connected. The pilot may use only one system at a time. In the mid 1980s, Pakistan requested an aircraft with greater radar capabilities. Both

1573-525: A number of simple countermeasures, most notably by dropping flares behind the target to provide false heat sources. That works only if the pilot is aware of the missile and deploys the countermeasures on time. The sophistication of modern seekers has rendered these countermeasures increasingly ineffective. The first IR devices were experimented with during World War II . During the war, German engineers were working on heat-seeking missiles and proximity fuses but did not have time to complete development before

1694-610: A number of victories in the middle east and Vietnam. A major upgrade program for the Redeye started in 1967, as the Redeye II. Testing did not begin until 1975 and the first deliveries of the now renamed FIM-92 Stinger began in 1978. An improved rosette seeker was added to the B model in 1983, and several additional upgrades followed. Sent to the Soviet–Afghan War , they claimed a 79% success rate against Soviet helicopters, although this

1815-829: A period of manufacturing stretching almost 50 years. At the China International Aviation & Aerospace Exhibition in 2018, a display showing the J-7 as an unmanned platform was shown. During August 2005, Namibia ordered 12 F-7NMs for its air force; Chinese sources reported the delivery in November 2006. The model procured is believed to be a variation of the F-7PG acquired by Pakistan with Grifo MG radar. In early 2008, Nigeria procured 12 F-7NI fighters and three FT-7NI trainers to replace its existing inventory of MiG-21 fighters. On September 20, 2018, two Nigerian F-7Ni aircraft crashed into Katamkpehir, Abuja, killing one pilot after

1936-494: A position where the missile would be able to continue tracking even after launch. This problem also led to efforts to make new missiles that would hit their targets even if launched under these less-than-ideal positions. In the UK this led to the SRAAM project, which was ultimately the victim of continually changing requirements. Two US programmes, AIM-82 and AIM-95 Agile , met similar fates. New seeker designs began to appear during

2057-498: A practical detector. Nevertheless, it was used for some time by the US Navy as a secure communications system. In 1930 the introduction of the Ag–O–Cs ( silver – oxygen – cesium ) photomultiplier provided the first practical solution to the detection of IR, combining it with a layer of galena as the photocathode . Amplifying the signal emitted by the galena, the photomultiplier produced

2178-563: A supersonic version. At this stage the concept was for a defensive weapon fired rearward out of a long tube at the back end of bomber aircraft . In April 1949 the Firebird missile project was cancelled and MX-904 was redirected to be a forward-firing fighter weapon. The first test firings began in 1949, when it was given the designation AAM-A-2 (Air-to-air Missile, Air force, model 2) and the name Falcon. IR and semi-active radar homing (SARH) versions both entered service in 1956, and became known as

2299-447: A transparent plate with a sequence of opaque segments painted on them that was placed in front of the IR detector. The plate spins at a fixed rate, which causes the image of the target to be periodically interrupted, or chopped . The Hamburg system developed during the war is the simplest system, and easiest to understand. Its chopper was painted black on one half with the other half left transparent. For this description we consider

2420-429: A useful output that could be used for detection of hot objects at long ranges. This sparked developments in a number of nations, notably the UK and Germany where it was seen as a potential solution to the problem of detecting night bombers . In the UK, research was plodding, with even the main research team at Cavendish Labs expressing their desire to work on other projects, especially after it became clear that radar

2541-568: A very desirable device. Kutzscher's team developed a system with the Eletroacustic Company of Kiel known as Hamburg , which was being readied for installation in the Blohm & Voss BV 143 glide bomb to produce an automated fire-and-forget anti-shipping missile. A more advanced version allowed the seeker to be directed off-axis by the bombardier in order to lock on to a target to the sides, without flying directly at it. However, this presented

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2662-531: Is a Chinese fighter aircraft . It is a license-built version of the Soviet Mikoyan-Gurevich MiG-21 , and thus shares many similarities with that aircraft. The aircraft is armed with short-range, infrared homing air-to-air missiles and is mainly designed for short range air-to-air combat. The aircraft is also used for close air support. On 30 March 1962, the Soviet Union and China signed

2783-435: Is a passive weapon guidance system which uses the infrared (IR) light emission from a target to track and follow it seamlessly. Missiles which use infrared seeking are often referred to as "heat-seekers" since infrared is radiated strongly by hot bodies. Many objects such as people, vehicle engines and aircraft generate and emit heat and so are especially visible in the infrared wavelengths of light compared to objects in

2904-622: Is debated. The Soviets likewise improved their own versions, introducing the 9K34 Strela-3 in 1974, and the greatly improved dual-frequency 9K38 Igla in 1983, and Igla-S in 2004. The three main materials used in the infrared sensor are lead(II) sulfide (PbS), indium antimonide (InSb) and mercury cadmium telluride (HgCdTe). Older sensors tend to use PbS, newer sensors tend to use InSb or HgCdTe. All perform better when cooled, as they are both more sensitive and able to detect cooler objects. Early infrared seekers were most effective in detecting infrared radiation with shorter wavelengths, such as

3025-436: Is not required, instead, both signals can be extracted from a single photocell with the use of electrical delays or a second reference signal 90 degrees out of phase with the first. This system produces a signal that is sensitive to the angle around the clock face, the bearing , but not the angle between the target and the missile centerline, the angle off (or angle error ). This was not required for anti-ship missiles where

3146-437: Is set too small the image from the target is too small to create a useful signal, while setting it too large makes it inaccurate. For this reason, linear scanners have inherent accuracy limitations. Additionally, the dual reciprocating motion is complex and mechanically unreliable, and generally two separate detectors have to be used. Most early seekers used so-called spin-scan , chopper or reticle seekers. These consisted of

3267-545: The AIM-4 Falcon after 1962. The Falcon was a complex system offering limited performance, especially due to its lack of a proximity fuse, and managed only a 9% kill ratio in 54 firings during Operation Rolling Thunder in the Vietnam War . However, this relatively low success rate must be appreciated in the context of all these kills representing direct hits, something that was not true of every kill by other American AAMs. In

3388-554: The AIM-9M Sidewinder and Stinger use compressed gas like argon to cool their sensors in order to lock onto the target at longer ranges and all aspects. (Some such as the AIM-9J and early-model R-60 used a peltier thermoelectric cooler ). The detector in early seekers was barely directional, accepting light from a very wide field of view (FOV), perhaps 100 degrees across or more. A target located anywhere within that FOV produces

3509-552: The Bangladesh Air Force entered service in 2013. The F-7BGI is one of the most advanced variants, and the last production model of the F-7/J-7 family. During the 1980s, Pakistan launched Project Sabre II in an effort to increase the effectiveness of its F-7 fleet by redesigning and upgrading the airframe. The program produced to a design study which was drawn up by engineers from Northrop Grumman, China and Pakistan, but by 1989,

3630-464: The Hamburg , an AC signal was generated that matched the rotational frequency of the disk. However, in this case the signal does not turn on and off with angle, but is constantly being triggered very rapidly. This creates a series of pulses that are smoothed out to produce a second AC signal at the same frequency as the test signal, but whose phase is controlled by the actual position of the target relative to

3751-575: The JF-17 Thunder multirole fighter, have succeeded it in the export market. To date, large numbers of J-7s remain in service with multiple export customers, with PLAAF retiring the fleet in 2023. In the 1950s and early 1960s, the Soviet Union shared a large proportion of its conventional weapons technology with its neighbor, China . One such example is the MiG-19 , which was locally produced by China as

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3872-622: The Second Congo War . Their only deployment in the DR Congo took place in January 2001, when four aircraft were to participate in the burial ceremony for the assassinated president, Laurent-Désiré Kabila . During the journey from Zimbabwe to Kinshasa , one of them crashed, with its pilot ejecting safely. Moreover, on the return trip, two aircraft were damaged on landing, although both were repaired and returned to service. The deployment of F-7As near

3993-575: The Shenyang J-6 from as early as 1958. During the same decade, the even more capable MiG-21 had been developed by the Soviets; this fighter, being inexpensive but fast, suited the strategy of forming large groups of 'people's fighters' to overcome the technological advantages of Western aircraft. However, the Sino-Soviet split abruptly ended initial cooperation efforts; between 28 July and 1 September 1960,

4114-426: The "Sun Tracker", was being developed as a possible guidance system for an intercontinental ballistic missile . Testing this system led to the 1948 Lake Mead Boeing B-29 crash . USAAF project MX-798 was awarded to Hughes Aircraft in 1946 for an infrared tracking missile. The design used a simple reticle seeker and an active system to control roll during flight. This was replaced the next year by MX-904, calling for

4235-410: The 1960s. A new generation developed in the 1970s and the 1980s made great strides and significantly improved their lethality. The latest examples from the 1990s and on have the ability to attack targets out of their field of view (FOV) behind them and even to pick out vehicles on the ground. IR seekers are also the basis for many semi-automatic command to line of sight (SACLOS) weapons. In this use,

4356-474: The 1970s and led to a series of more advanced missiles. A major upgrade to the Sidewinder began, providing it with a seeker that was sensitive enough to track from any angle, giving the missile all aspect capability for the first time. This was combined with a new scanning pattern that helped reject confusing sources (like the sun reflecting off clouds) and improve the guidance towards the target. A small number of

4477-420: The 1980s, Iran procured a number of F-7s, despite Chinese officials issuing denials of directly supplying military equipment to the country at that time. Despite its use as a frontline fighter, the type has not been involved in any known combat actions. By the 21st century, it was largely relegated to use as a trainer aircraft. The F-7 has also been used as a flying test bed for various indigenous technologies. In

4598-436: The 4.2 micrometre emissions of the carbon dioxide efflux of a jet engine . This made them useful primarily in tail-chase scenarios, where the exhaust was visible and the missile's approach was carrying it toward the aircraft as well. In combat these proved extremely ineffective as pilots attempted to make shots as soon as the seeker saw the target, launching at angles where the target's engines were quickly obscured or flew out of

4719-490: The Block III version was put into production. The Soviets started development of two almost identical weapons in 1964, Strela-1 and Strela-2. Development of these proceeded much more smoothly, as the 9K32 Strela-2 entered service in 1968 after fewer years of development than the Redeye. Originally a competing design, the 9K31 Strela-1 was instead greatly increased in size for vehicle applications and entered service at around

4840-512: The Chinese had to re-engineer the intercepted MiG-21 airframes in order to achieve their original capabilities. China later developed the Shenyang J-8 based both on the expertise gained by the program, and by utilizing the incomplete technical information acquired from the Soviet Ye-152 developmental jet. During May 2013, production of the J-7 was permanently terminated, bringing to a close

4961-659: The Fighter China project, it led to the creation of the JF-17 Thunder multirole fighter. The aircraft satisfied a requirement issued by the Pakistani Air Force for an affordable and modern combat aircraft, and the country is in the process of replacing its entire F-7 fleet with JF-17s. In 1991, the Sri Lanka Air Force (SLAF) was looking for a jet attack aircraft to provide fast close air support to its army. With western countries refusing to sell attack aircraft,

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5082-527: The Government of Sri Lanka approached China for the purchase of several Nanchang Q-5s , which had the range and payload capacity needed by the SLAF, and was already used by Pakistan and Bangladesh. Due to pressure from the west, China agreed to sell a small number of F-7BS fighters which allowed the SLAF to restore its capabilities that were lost a decade back. Due to the type's comparative lack of endurance and payload,

5203-549: The J-7 reportedly commenced at the Shenyang Aircraft Factory , but due to various factors including the Cultural Revolution , mass production was only truly achieved during the 1980s. Numerous models of the J-7 were developed, featuring improvements in areas such as the armament, avionics , and wing design. The aircraft is principally operated by the People's Liberation Army Air Force (PLAAF), but numerous international operators have bought their own J-7s. Outside of China,

5324-528: The J-7, some of which are equipped to use European weaponry, such as French R.550 Magic missiles. The Discovery Channel's Wings Over The Red Star series claims that the Chinese intercepted several Soviet MiG-21s en route to North Vietnam (during the Vietnam War ), but these aircraft did not perform in a manner consistent with their original specifications, suggesting that the Chinese actually intercepted down-rated aircraft that were intended for export, rather than fully capable production aircraft. For this reason,

5445-500: The J-7, the J-7G, entered service with the PLAAF in 2003. The principal role of the J-7 in Chinese service is to provide local air defense and tactical air superiority. Large numbers are to be employed to deter enemy air operations. In June 2021, four J-7s participated in a combat drill conducted near Taiwan's air defense identification zone. The decommissioning of the J-7 began in 2018, with

5566-590: The MiG-21F-13 version was manufactured under license by Aero Vodochody in Czechoslovakia, under the name of Aero S-106. Aero Vodochody (then Středočeské strojírny, n.p.) built a total of 194 planes during this period, under the cover designation article Z-159. It followed the MiG-15 and MiG-19S built in the Vodochody factory from the fifties to sixties. The sole locally built version of the MiG-21F-13 differed externally from

5687-576: The R-73 problem was initially going to be the ASRAAM , a pan-European design that combined the performance of the R-73 with an imaging seeker. In a wide-ranging agreement, the US agreed to adopt ASRAAM for their new short-range missile, while the Europeans would adopt AMRAAM as their medium-range weapon. However, ASRAAM soon ran into intractable delays as each of the member countries decided a different performance metric

5808-659: The SLAF has periodically used its F-7s for pilot training purposes. Early in 2008, the air force received six more advanced F-7Gs, to use primarily as interceptors. All of the F-7Gs, F-7BS' and FT-7s are flown by the No 5 Jet Squadron . The SLAF has repeatedly deployed its F-7BS to conduct ground-attack missions against the Liberation Tigers of Tamil Eelam (LTTE). Sri Lankan officials reported that on 9 September 2008, three F-7s were scrambled after two rebel-flown Zlín-143s were detected by

5929-430: The Soviet Union withdrew its advisers from China, resulting in the J-7 project coming to a halt in China. During February 1962, Soviet Premier Nikita Khrushchev unexpectedly wrote to Mao Zedong to inform him that the Soviet Union was willing to transfer MiG-21 technology to China, and he asked the Chinese to promptly send their representatives to the Soviet Union to discuss arrangements. The Chinese viewed this offer as

6050-492: The Soviet Union. One of the major flaws was with the hydraulic systems, which grounded up to 70% of some squadron's aircraft until upgrades were made. Another major modification was to the fuel storage, increasing the aircraft's stability. The MiG-21 carries most of its fuel in the forward fuselage, causing the center of gravity to shift and become unstable after about 45 minutes of operation. The J-7 has redesigned fuel tanks and significantly larger drop tanks in order to maintain

6171-704: The Soviet-built examples by the solid dural sheet fairing behind the cockpit canopy, as opposed to the transparent one on the original Soviet MiGs. These machines were built for the Czechoslovak Air Force and also for export. The R13-300 engines were imported from the Soviet Union. The production of the MiG-21 in India under license by Hindustan Aeronautics in Nasik started with the MiG-21FL in 1966 in four phases starting with

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6292-601: The Sudanese Army. The Tanzanian Air Force deployed its F-7As during the Uganda–Tanzania War against Uganda and Libya , fought between 1978 and 1979. Forming a major component of Tanzania's combat aircraft, the type facilitated the defeat of the nominally stronger Uganda Army Air Force during the air campaign. Due to their very limited operational capabilities in the absence of ground support from radars, Zimbabwean F-7s were never used in combat operations during

6413-464: The ability to be fired at targets completely out of view of the seeker; after firing the missile would orient itself in the direction indicated by the launcher and then attempt to lock on. When combined with a helmet mounted sight , the missile could be cued and targeted without the launch aircraft first having to point itself at the target. This proved to offer significant advantages in combat, and caused great concern for Western forces. The solution to

6534-477: The aircraft and thus produce an ever-increasing signal while the aircraft is providing little or none. Additionally, as the missile approaches the target, smaller changes in relative angle are enough to move it out of this center null area and start causing control inputs again. With a bang-bang controller, such designs tend to begin to overreact during the last moments of the approach, causing large miss distances and demanding large warheads. A great improvement on

6655-410: The angle-off and feed that into the controls as well. This can be accomplished with the same disk and some work on the physical arrangement of the optics. Since the physical distance between the radial bars is larger at the outer position of the disk, the image of the target on the photocell is also larger, and thus has greater output. By arranging the optics so the signal is increasingly cut off closer to

6776-491: The assembly of CKD kits, moving on to subassemblies, parts, and finally advancing to production from scratch. 205 MiG-21FLs, designated Type 77 and nicknamed Trishul ("Trident"), were built in India between 1966 and 1972; the first one built entirely from Indian-made components was delivered to the IAF on 19 October 1970, with the first Indian-made R11F2S-300 powerplant leaving the assembly line on 2 January 1969. In 1971 HAL production

6897-479: The background. Infrared seekers are passive devices, which, unlike radar , provide no indication that they are tracking a target. That makes them suitable for sneak attacks during visual encounters or over longer ranges when they are used with a forward looking infrared or similar cueing system. Heat-seekers are extremely effective: 90% of all United States air combat losses between 1984 and 2009 were caused by infrared-homing missiles. They are, however, subject to

7018-451: The basic spin-scan concept is the conical scanner or con-scan . In this arrangement, a fixed reticle is placed in front of the detector and both are positioned at the focus point of a small Cassegrain reflector telescope. The secondary mirror of the telescope is pointed slightly off-axis, and spins. This causes the image of the target to be spun around the reticle , instead of the reticle itself spinning. Consider an example system where

7139-409: The center of the disk, the resulting output signal varies in amplitude with the angle-off. However, it will also vary in amplitude as the missile approaches the target, so this is not a complete system by itself and some form of automatic gain control is often desired. Spin-scan systems can eliminate the signal from extended sources like sunlight reflecting from clouds or hot desert sand. To do this,

7260-478: The center of the operator's telescope. SACLOS systems of this sort have been used both for anti-tank missiles and surface-to-air missiles , as well as other roles. The infrared sensor package on the tip or head of a heat-seeking missile is known as the seeker head . The NATO brevity code for an air-to-air infrared-guided missile launch is Fox Two . The ability of certain substances to give off electrons when struck by infrared light had been discovered by

7381-401: The centerline it was. Other systems used a second scanning disk with radial slits to provide the same result but from a second output circuit. AEG developed a much more advanced system during the war, and this formed the basis of most post-war experiments. In this case, the disk was pattered with a series of opaque regions, often in a series of radial stripes forming a pizza-slice pattern. Like

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7502-472: The code name Blue Jay . Designed as an anti-bomber weapon, the Blue Jay was larger, much heavier and flew faster than its US counterparts, but had about the same range. It had a more advanced seeker, using PbTe and cooled to −180 °C (−292.0 °F) by anhydrous ammonia to improve its performance. One distinguishing feature was its faceted nose cone, which was selected after it was found ice would build up on

7623-401: The control system and commands the missile to turn up. A second cell placed at the 3 o'clock position completes the system. In this case, the switching takes place not at the 9 and 3 o'clock positions, but 12 and 6 o'clock. Considering the same target, in this case, the waveform has just reached its maximum positive point at 12 o'clock when it is switched negative. Following this process around

7744-491: The country's northern border successfully checked Yugoslav incursions into Albanian airspace. Throughout the mid-1990s, the PLAAF began to replace its J-7B inventory with the substantially redesigned and improved J-7E variant. The wings of the J-7E have a new "double delta" design offering improved aerodynamics and increased fuel capacity, and the J-7E also features a more powerful engine and improved avionics. The newest version of

7865-401: The detector, or in the case of Madrid , two metal vanes were tilted to block off more or less of the signal. By comparing the time the flash was received to the location of the scanner at that time, the vertical and horizontal angle-off can be determined. However, these seekers also have the major disadvantage that their FOV is determined by the physical size of the slit (or opaque bar). If this

7986-410: The disk spinning clockwise as seen from the sensor; we will call the point in the rotation when the line between the dark and light halves is horizontal and the transparent side is on the top to be the 12 o'clock position. A photocell is positioned behind the disk at the 12 o'clock position. A target is located just above the missile. The sensor begins to see the target when the disk is at 9 o'clock, as

8107-401: The disk. By comparing the phase of the two signals, both the vertical and horizontal correction can be determined from a single signal. A great improvement was made as part of the Sidewinder program, feeding the output to the pilot's headset where it creates a sort of growling sound known as the missile tone that indicates that the target is visible to the seeker. In early systems this signal

8228-438: The emissions from the targets. This led to the practical discovery that the vast majority of the IR output from a piston-engine aircraft was between 3 and 4.5 micrometers. The exhaust was also a strong emitter, but cooled rapidly in the air so that it did not present a false tracking target. Studies were also made on atmospheric attenuation, which demonstrated that air is generally more transparent to IR than visible light, although

8349-433: The entire seeker assembly is mounted on a gimbal system that allows it to track the target through wide angles, and the angle between the seeker and the missile aircraft is used to produce guidance corrections. This gives rise the concepts of instantaneous field of view (IFOV) which is the angle the detector sees, and the overall field of view, also known as the tacking angle or off-boresight capability , which includes

8470-494: The famous Indian polymath Jagadish Chandra Bose in 1901, who saw the effect in galena , known today as lead sulfide, PbS. There was little application at the time, and he allowed his 1904 patent to lapse. In 1917, Theodore Case , as part of his work on what became the Movietone sound system , discovered that a mix of thallium and sulfur was much more sensitive, but was highly unstable electrically and proved to be of little use as

8591-583: The first effective French design, the R.530 , in 1962. The Soviets introduced their first infrared homing missile, the Vympel K-13 in 1961, after reverse engineering a Sidewinder that stuck in the wing of a Chinese MiG-17 in 1958 during the Second Taiwan Strait Crisis . The K-13 was widely exported, and faced its cousin over Vietnam throughout the war. It proved even less reliable than the AIM-9B it

8712-402: The fixed signal is filtered out. A significant problem with the spin-scan system is that the signal when the target is near the center drops to zero. This is because even its small image covers several segments as they narrow at the center, producing a signal similar enough to an extended source that it is filtered out. This makes such seekers extremely sensitive to flares, which move away from

8833-478: The fleet early on, and their ground-attack performance was not deemed sufficient. Since then, Myanmar has improved the F-7 fleet's capabilities via a modernisation programme. A series of upgrades were allegedly performed by a combination of Chinese and Israeli enterprises; although confirmed details on the arrangements have remained sparse, changes reportedly include the adoption of various Israeli-built missiles. During

8954-401: The handful of MiG-21F-13s supplied from the USSR, in order to make up for blueprints and documentation that had not yet been shipped over from the USSR at the time of the political rift. All subsequent development of the J-7 was indigenous to China and different from Soviet-made versions. The Guizhou JL-9 trainer, first flown in 2003, is also based on the MiG-21 airframe. Between 1962 and 1972

9075-403: The high degree of sensitivity required to lock onto the lower-level signals coming from the front and sides of an aircraft. Background heat from inside the sensor, or the aerodynamically heated sensor window, can overpower the weak signal entering the sensor from the target. ( CCDs in cameras have similar problems; they have much more "noise" at higher temperatures.) Modern all-aspect missiles like

9196-508: The largest operator of the J-7 is the Pakistan Air Force . Later generation Chinese aircraft, such as the Shenyang J-8 interceptor, were developed with the lessons learned from the J-7 programme. Several nations, including Zimbabwe , Tanzania , and Sri Lanka , deployed the type in offensive roles. In 2013, production of the J-7 was terminated after the delivery of 16 F-7BGI to the Bangladesh Air Force . Newer fighter aircraft, such as

9317-413: The location of the target by timing when the image disappeared (AEG) or reappeared (Kepka). The Kepka Madrid system had an instantaneous field of view (IFOV) of about 1.8 degrees and scanned a full 20 degree pattern. Combined with the movement of the entire seeker within the missile, it could track at angles as great as 100 degrees. Rheinmetall-Borsig and another team at AEG produced different variations on

9438-555: The missile's field of view. Such seekers, which are most sensitive to the 3 to 5 micrometre range, are now called single-color seekers. This led to new seekers sensitive to both the exhaust as well as the longer 8 to 13 micrometer wavelength range, which is less absorbed by the atmosphere and thus allows dimmer sources like the fuselage itself to be detected. Such designs are known as "all-aspect" missiles. Modern seekers combine several detectors and are called two-color systems. All-aspect seekers also tend to require cooling to give them

9559-456: The movement of the entire seeker assembly. Since the assembly cannot move instantly, a target moving rapidly across the missile's line of flight may be lost from the IFOV, which gives rise to the concept of a tracking rate , normally expressed in degrees per second. Some of the earliest German seekers used a linear-scan solution, where vertical and horizontal slits were moved back and forth in front of

9680-483: The name indicates a rangefinding-only unit. General Specifications of MiG-21 variants are listed below:- Data from General characteristics Performance Armament Data from General characteristics Performance Armament Data from General characteristics Performance Armament Chengdu J-7 The Chengdu J-7 ( Chinese : 歼-7; third generation export version F-7 ; NATO reporting name : Fishcan )

9801-399: The negative voltage portion of its waveform, so the switch inverts this back to positive. When the disk reaches the 9 o'clock position the cell switches again, no longer inverting the signal, which is now entering its positive phase again. The resulting output from this cell is a series of half-sine waves, always positive. This signal is then smoothed out to produce a DC output, which is sent to

9922-469: The next year. Wally Schirra recalls visiting the lab and watching the seeker follow his cigarette. The missile was given the name Sidewinder after a local snake; the name had a second significance as the sidewinder is a pit viper and hunts by heat, and moves in an undulating pattern not unlike the missile. The Sidewinder entered service in 1957, and was widely used during the Vietnam war. It proved to be

10043-484: The original MiG-21. During March 1964, domestic production of the J-7 reportedly commenced at the Shenyang Aircraft Factory. However, mass production efforts were severely hindered by an unexpected social and economic problem— the Cultural Revolution —that resulted in poor initial quality and slow progress. Achieving full domestic production had involved not only the local assembly of the aircraft itself, but

10164-469: The period the target is visible to the sensor, the AC waveform is in the positive voltage period, varying from zero to its maximum and back to zero. When the target disappears, the sensor triggers a switch that inverts the output of the AC signal. For instance, when the disk reaches the 3 o'clock position and the target disappears, the switch is triggered. This is the same instant that the original AC waveform begins

10285-487: The presence of water vapour and carbon dioxide produced several sharp drops in transitivity. Finally, they also considered the issue of background sources of IR, including reflections off clouds and similar effects, concluding this was an issue due to the way it changed very strongly across the sky. This research suggested that an IR seeker could home on a three-engine bomber at 5 kilometres (3.1 mi) with an accuracy of about 1 ⁄ 10 degree, making an IR seeker

10406-428: The problem that when the bomb was first released it was traveling too slowly for the aerodynamic surfaces to easily control it, and the target sometimes slipped out from the view of the seeker. A stabilized platform was being developed to address this problem. The company also developed a working IR proximity fuse by placing additional detectors pointing radially outward from the missile centerline. which triggered when

10527-571: The production of its various components and systems, including its turbojet powerplant. As a consequence, full-scale production of the J-7 was only truly achieved during the 1980s, by which time the original aircraft design was showing its age. By the 1980s, quantity production of the General Dynamics F-16 Fighting Falcon fighter was well underway in the United States ; this relatively-affordable single-engined western fighter

10648-421: The project was abandoned largely as a consequence of economic sanctions that the U.S. imposed on Pakistan. That same year, Grumman and China initiated a new design study in another attempt to redesign the F-7 but that effort was also abandoned when the U.S. placed sanctions on China in response to the 1989 Tiananmen Square protests . In 1991, a third initiative involving the F-7 was launched; originally known as

10769-435: The radar system by converting to an Italian FIAR Grifo-7 radar, more than tripled the effective range of the radar, as well as greatly increased the maximum angle for target detection. The J-7 only reached its Soviet-designed capabilities in the mid 1980s. Being relatively affordable, it was widely exported as the F-7, often with Western systems incorporated, such as to Pakistan. There are over 20 different export variants of

10890-472: The recent years, maintaining the fleet's operational status has reportedly become difficult. This is caused by the limited availability of spare parts, despite efforts by domestic industries to fill in, but also by the age of the airframes, which have accumulated excessive numbers of flight hours. Iranian F-7s have featured in several movies, often portraying Iraqi MiG-21s during the Iran–Iraq War . One tells

11011-511: The resulting L models were rushed to the UK just prior to their engagement in the Falklands War , where they achieved an 82% kill ratio, and the misses were generally due to the target aircraft flying out of range. The Argentine aircraft, equipped with Sidewinder B and R.550 Magic , could only fire from the rear aspect, which the British pilots simply avoided by always flying directly at them. The L

11132-421: The reticle is modified by making one half of the plate be covered not with stripes but a 50% transmission color. The output from such a system is a sine wave for half of the rotation and a constant signal for the other half. The fixed output varies with the overall illumination of the sky. An extended target that spans several segments, like a cloud, will cause a fixed signal as well, and any signal that approximates

11253-410: The rotation causes a series of chopped-off positive and negative sine waves. When this is passed through the same smoothing system, the output is zero. This means the missile does not have to correct left or right. If the target were to move to the right, for instance, the signal would be increasingly positive from the smoother, indicating increasing corrections to the right. In practice a second photocell

11374-593: The same output signal. Since the goal of the seeker is to bring the target within the lethal radius of its warhead, the detector must be equipped with some system to narrow the FOV to a smaller angle. This is normally accomplished by placing the detector at the focal point of a telescope of some sort. This leads to a problem of conflicting performance requirements. As the FOV is reduced, the seeker becomes more accurate, and this also helps eliminate background sources which helps improve tracking. However, limiting it too much allows

11495-549: The same systems for use on tanks , and deployed a number of models through the war, with limited production of the FG 1250 beginning in 1943. This work culminated in the Zielgerät 1229 Vampir riflescope which was used with the StG 44 assault rifle for night use. The devices mentioned previously were all detectors, not seekers. They either produce a signal indicating the general direction of

11616-527: The same technologies have appeared in the Chinese PL-10 and Israeli Python-5 . Based on the same general principles as the original Sidewinder, in 1955 Convair began studies on a small man-portable missile ( MANPADS ) that would emerge as the FIM-43 Redeye . Entering testing in 1961, the preliminary design proved to have poor performance, and a number of major upgrades followed. It was not until 1968 that

11737-461: The same time. The UK began development of its Blowpipe in 1975, but placed the seeker on the launcher instead of the missile itself. The seeker sensed both the target and the missile and sent corrections to the missile via a radio link. These early weapons proved ineffective, with the Blowpipe failing in almost every combat use, while the Redeye fared somewhat better. The Strela-2 did better and claimed

11858-615: The same year as MX-798, 1946, William B. McLean began studies of a similar concept at the Naval Ordnance Test Station, today known as Naval Air Weapons Station China Lake . He spent three years simply considering various designs, which led to a considerably less complicated design than the Falcon. When his team had a design they believed would be workable, they began trying to fit it to the newly introduced Zuni 5-inch rocket . They presented it in 1951 and it became an official project

11979-403: The seeker is mounted on a trainable platform on the launcher and the operator keeps it pointed in the general direction of the target manually, often using a small telescope. The seeker does not track the target, but the missile, often aided by flares to provide a clean signal. The same guidance signals are generated and sent to the missile via thin wires or radio signals, guiding the missile into

12100-410: The seeker's mirror is tilted at 5 degrees, and the missile is tracking a target that is currently centered in front of the missile. As the mirror spins, it causes the image of the target to be reflected in the opposite direction, so in this case the image is moving in a circle 5 degrees away from the reticle's centerline. That means that even a centered target is creating a varying signal as it passes over

12221-405: The signal strength began to decrease, which it did when the missile passed the target. There was work on using a single sensor for both tasks instead of two separate ones. Other companies also picked up on the work by Eletroacustic and designed their own scanning methods. AEG and Kepka of Vienna used systems with two movable plates that continually scanned horizontally or vertically, and determined

12342-576: The spinning-disk system. In the post-war era, as the German developments became better known, a variety of research projects began to develop seekers based on the PbS sensor. These were combined with techniques developed during the war to improve accuracy of otherwise inherently inaccurate radar systems, especially the conical scanning system. One such system developed by the US Army Air Force (USAAF), known as

12463-571: The standard radar and the British Marconi radar were plagued by ground clutter, but China did not have any experience with air to ground radar at the time. In 1984, Pakistan provided assistance by having their American-trained F-16 pilots provide training on proper ground attack radar operation, which enabled the Chinese to develop the J-7M. In the late 1980s, the J-7MP and J-7PG introduced significant upgrades to

12584-598: The story of an Islamic Republic of Iran Air Force strike on the Iraqi nuclear reactor at Osirak on 30 September 1980. Another one, "Attack on H3", tells the story of the 810 km-deep raid against Iraqi Air Force airfields on 4 April 1981, and other movies depicting the air combat in 1981 that resulted in the downing of around 70 Iraqi aircraft. Iraqi F-7Bs were never used in combat, but only as advanced trainers. The Bangladeshi Air Force currently operates FT-7MB Airguards, and F-7BG and F-7BGI interceptors. The 16 F-7BGIs of

12705-416: The table below. * = limited (3-minute) "extra-power" reheat at altitudes 4000m (13,120 ft) or less. The following table shows the possible ordnance loads of various models of the MiG-21. The number in the pylons column indicates the number of stores carried per pylon. Notes to table: * ADF = Automatic direction finder; an asterisk by the name means there is no DME module present. ** = An asterisk by

12826-407: The target is moving very slowly relative to the missile and the missile quickly aligns itself to the target. It was not appropriate for air-to-air use where the velocities were greater and smoother control motion was desired. In this case, the system was changed only slightly so the modulating disk was patterned in a cardioid which blanked out the signal for more or less time depending on how far from

12947-483: The target to move out of the FOV and be lost to the seeker. To be effective for guidance to the lethal radius, tracking angles of perhaps one degree are ideal, but to be able to continually track the target safely, FOVs on the order of 10 degrees or more are desired. This situation leads to the use of a number of designs that use a relatively wide FOV to allow easy tracking, and then process the received signal in some way to gain additional accuracy for guidance. Generally,

13068-465: The target, or in the case of later devices, an image. Guidance was entirely manual by an operator looking at the image. There were a number of efforts in Germany during the war to produce a true automatic seeker system, both for anti-aircraft use as well as against ships. These devices were still in development when the war ended; although some were ready for use, there had been no work on integrating them with

13189-414: The transparent portion of the chopper is aligned vertically at the target at 12 o'clock becomes visible. The sensor continues to see the target until the chopper reaches 3 o'clock. A signal generator produces an AC waveform that had the same frequency as the rotational rate of the disk. It is timed so the waveform reaches its maximum possible positive voltage point at the 12 o'clock position. Thus, during

13310-485: The war ended. Truly practical designs did not become possible until the introduction of conical scanning and miniaturized vacuum tubes during the war. Anti-aircraft IR systems began in earnest in the late 1940s, but the electronics and the entire field of rocketry were so new that they required considerable development before the first examples entered service in the mid-1950s. The early examples had significant limitations and achieved very low success rates in combat during

13431-621: The whole fleet set to retire in 2023. According to the US Air Force China Aerospace Studies Institute , the retirement of J-7 marked the PLAAF's transition to a fleet composed of only fourth-generation and fifth-generation aircraft. According to the Chinese media, PLAAF also considered turning J-7 into drones for training tools and aerial decoys. During the 1990s, Myanmar reportedly established four squadrons of F-7s, which have been primarily used for air defense duties. Technical difficulties have reportedly plagued

13552-530: Was also sent along with parts and technical documents. As the Chinese had expected, following the delivery of kits, parts and documents to Shenyang Aircraft Factory five months after the deal was signed, it was discovered that some technical documents provided by the Soviets were incomplete and that several parts could not be used. China set about to engineer the aircraft for local production; in doing so, they successfully solved 249 major issues and reproduced eight major technical documents that were not provided by

13673-432: Was based on, with the guidance system and fuse suffering continual failure. As Vietnam revealed the terrible performance of existing missile designs, a number of efforts began to address them. In the US, minor upgrades to the Sidewinder were carried out as soon as possible, but more broadly pilots were taught proper engagement techniques so they would not fire as soon as they heard the missile tone, and would instead move to

13794-410: Was considerably more agile than the J-7, even with the former carrying a greater payload. In 1987, the J-7E was introduced, having a greatly improved wing, among other improvements. It was roughly 45% more maneuverable, and its takeoff and landing performance was greatly increased. It was also equipped with a helmet mounted sight, as well as being the first MiG-21 variant to be equipped with HOTAS and

13915-412: Was fed directly to the control surfaces, causing rapid flicking motions to bring the missile back into alignment, a control system known as "bang-bang". Bang-bang controls are extremely inefficient aerodynamically, especially as the target approaches the centerline and the controls continually flick back and forth with no real effect. This leads to the desire to either smooth out these outputs, or to measure

14036-582: Was going to be a better solution. Nevertheless, Frederick Lindemann , Winston Churchill 's favorite on the Tizard Committee , remained committed to IR and became increasingly obstructionist to the work of the Committee who were otherwise pressing for radar development. Eventually they dissolved the Committee and reformed, leaving Lindemann off the roster, and filling his position with well known radio expert Edward Victor Appleton . In Germany, radar research

14157-456: Was more important. The US eventually bowed out of the program, and instead adapted the new seekers developed for ASRAAM on yet another version of the Sidewinder, the AIM-9X. This so extends its lifetime that it will have been in service for almost a century when the current aircraft leave service. ASRAAM did, eventually, deliver a missile that has been adopted by a number of European forces and many of

14278-518: Was not given nearly the same level of support as in the UK, and competed with IR development throughout the 1930s. IR research was led primarily by Edgar Kutzscher at the University of Berlin working in concert with AEG . By 1940 they had successfully developed one solution; the Spanner Anlage (roughly "Peeping Tom system") consisting of a detector photomultiplier placed in front of the pilot, and

14399-506: Was previously off-limits to foreigners. The visit's authorization was personally given by Nikita Khrushchev, and on 30 March 1962, the technology transfer deal was signed. However, given the state of political relations between the two countries, the Chinese were not optimistic about gaining the technology, and allegedly made preparations to reverse engineer the aircraft. Russian sources state that several complete MiG-21s were sent to China, flown by Soviet pilots, while MiG-21Fs in kit form

14520-514: Was so effective that aircraft hurried to add flare countermeasures, which led to another minor upgrade to the M model to better reject flares. The L and M models would go on to be the backbone of Western air forces through the end of the Cold War era. An even larger step was taken by the Soviets with their R-73 , which replaced the K-13 and others with a dramatically improved design. This missile introduced

14641-490: Was switched to an improved version of the MiG-21M ( izdeliye 96), which was designated Type 88 by HAL; as this variant was produced exclusively in India, no izdeliye designation is applicable. The first Type 88 MiG-21M was delivered to the IAF on 14 February 1973 and the last on 12 November 1981, with a total of 158 built. The last variant to be produced by HAL was the MiG-21bis. A total of 75 were built in 1977 from CKD kits, and

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