103-540: The Advanced Short Range Air-to-Air Missile ( ASRAAM ), also known by its United States designation AIM-132 , is an imaging infrared homing air-to-air missile , produced by MBDA UK , that is designed for close-range combat. It is in service in the Royal Air Force (RAF), replacing the AIM-9 Sidewinder . The ASRAAM is designed to allow the pilot to fire and then turn away before the opposing aircraft can close for
206-434: A "fire and forget" capacity. Reportedly, the system has achieved a 90% success rate during operations. This system is not to be confused with the dedicated surface-launched development of ASRAAM, CAMM/ Sky Sabre air defence system. On 7 May 2024 footage was published showing the first confirmed loss of a Ukrainian ASRAAM Supacat based launcher which was destroyed by a ZALA Lancet . Royal Air Force / Fleet Air Arm - Equips
309-824: A LOAL ( Lock-on after launch ) ability which is a distinct advantage when the missile is carried in an internal bay such as in the F-35 Lightning II . However in 2012 the requirement for ASRAAM internal carriage on the F-35 was dropped, and the aircraft now uses external carriage only. The ASRAAM warhead is triggered either by laser proximity fuse or impact. A laser proximity fuse was selected because RF fuses are vulnerable to EW intervention from enemy jammers. The increased diameter of ASRAAM also provides space for increased computing power, and so improved counter counter-measure capabilities compared with other dogfighting missiles such as AIM-9X. On 8 July 2014, Indian Ministry of Defence signed
412-610: 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
515-604: A family of weapons with a number of additional missile variants on order or in development. On 14 December 2021 a RAF Typhoon operating against Islamic State in southern Syria shot down a hostile drone with an ASRAAM missile. This was the first time the British military had shot down an enemy aircraft since the Falklands War . In August 2023 it emerged that Ukraine had been provided an unknown number of improvised ground-based launch platforms for ASRAAM. Developed in four months by
618-555: A joint MBDA and MoD team, It has been used by the Armed Forces of Ukraine to provide short range air defence ( SHORAD ) against Russian aerial threats such as helicopters, cruise missiles and drones such as the HESA Shahed 136 . Images of the system appear to show a twin-launcher mounted on the back of a Supacat 6x6 vehicle, allowing it to remain mobile, whilst guidance can be provided by a Hawkeye electro-optical suite. The missile has
721-603: 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
824-462: 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
927-454: 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
1030-525: 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
1133-610: 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
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#17328450990781236-494: 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
1339-498: 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
1442-466: A primarily British and German team would develop a short-range air-to-air missile to replace the Sidewinder. The team included the UK (Hawker Siddeley, by this point known as BAe Dynamics) and Germany ( Bodensee Gerätetechnik ) sharing 42.5 per cent of the effort each, Canada at 10 per cent and Norway at 5 per cent. The US assigned this missile the name AIM-132 ASRAAM. The rapid decline and eventual fall of
1545-514: A shot. It flies at over Mach 3 to ranges in excess of 25 kilometres (16 mi). It retains a 50 g maneuverability provided by body lift and tail control. The project started as a British-German collaboration in the 1980s. It was part of a wider agreement in which the US would develop the AIM-120 AMRAAM for medium-range use, while the ASRAAM would replace the Sidewinder with a design that would cover
1648-561: A simple strapdown inertial guidance system to know where to look after launch. Examples of LOAL weapons include the Advanced Short Range Air-to-Air Missile ( ASRAAM ) and later versions of the AGM-114 Hellfire anti-tank missile . The older method of launch has retroactively become known as lock-on before launch (LOBL), although this term is not commonly used and is a " backronym " that distinguishes it from
1751-451: A smokescreen for financial and defence industrial share issues. This left Britain in charge of the project and they began redefining it purely to RAF needs, sending out tenders for the new design in August 1989. This led to the selection of a new Hughes focal plane array imaging array seeker instead of the more conventional design previously used, dramatically improving performance and countermeasure resistance. A UK contest in 1990 examined
1854-563: 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
1957-496: A target after being launched from a carrier vehicle. The term is normally used in reference to airborne weapons, especially air-to-air missiles . LOAL is an important part of modern weapon systems as it allows a weapon to be carried internally (onboard an aircraft ) to increase stealth and then to acquire a target once it has been launched. LOAL systems normally rely on cuing from a helmet-mounted sight or onboard sensors such as radar or forward-looking infrared (FLIR) and use
2060-447: 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
2163-429: 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
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#17328450990782266-568: 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
2369-496: A £250m ($ 428m) contract with MBDA to purchase 384 ASRAAM short range air-to-air missile to equip its SEPECAT/HAL Jaguar strike aircraft fleet and replace the ageing Matra Magic R550 . MBDA's offering overcame competition from competitors including Rafael's Python-5 missile, emerging as the winner in 2012. This built on an existing 2012 order for 493 MICA missiles to replace Matra S-530D and Magic II missiles as part of an Indian Air Force Mirage 2000 upgrade. In September 2015,
2472-459: Is a high speed, extremely manoeuvrable, heat-seeking, air-to-air missile. Built by MBDA UK, it is designed as a "fire-and-forget" missile. ASRAAM is intended to detect and launch against targets at much longer ranges, as far as early versions of the AMRAAM, in order to shoot down the enemy long before it closes enough to be able to fire its own weapons. In this respect the ASRAAM shares more in common with
2575-402: Is a new 128×128 resolution imaging infrared focal plane array (FPA) seeker manufactured by Hughes before they were acquired by Raytheon . This seeker has a long acquisition range, high countermeasures resistance, approximately 90-degree off-boresight lock-on capability, and the possibility to designate specific parts of the targeted aircraft (like cockpit, engines, etc.). The ASRAAM also has
2678-622: 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
2781-436: 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
2884-437: 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
2987-545: 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
3090-554: 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
3193-569: The AIM-9X with the F/A-18F, EA-18G and F-35A. Infrared homing Infrared homing 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
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3296-699: The Common Anti-Aircraft Modular Missile (CAMM) used by the British Army, Royal Navy and several allied forces in the surface-launched role. A surface-launched variant of the ASRAAM itself has been improvised for the Armed Forces of Ukraine . In the 1980s, NATO countries signed a Memorandum of Agreement that the United States would develop the AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM), while
3399-939: The DSEi conference in September 2007 it was announced that the UK MoD was funding a study by MBDA to investigate a replacement for the Rapier and Sea Wolf missiles for the Royal Navy and British Army respectively. The Common Anti-Air Modular Missile (CAMM) would share components with ASRAAM, such as the very low signature rocket motor from Roxel and the warhead and proximity fuze from Thales but with updated electronics, an active RF seeker and data link so allowing for mid-course corrections from suitably-equipped land or even air platforms. CAMM began entering service in 2018 and has since be sold to nine other nations for both land and naval use. It has since become
3502-464: 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
3605-678: The Indian Air Force is testing the compatibility of the ASRAAM weapons system with the Sukhoi Su-30MKI , and aims to make the ASRAAM its standardised short range missile across multiple aircraft types, including the Tejas . Final testing and operational clearance are to be achieved by the end of 2019. Bharat Dynamics Limited will produce the missile at its Bhanoor unit. The facility will also offer maintenance, repair and overhaul services. In 1995, Hughes and British Aerospace collaborated on
3708-612: The Soviet Union in the late 1980s led to considerably less interest in the ASRAAM. By February 1988 the US was already agitating for changes. In July 1989 the Germans exited the programme effectively ending the agreement. Various reasons are often cited including the ending of the Cold War and full realisation of the capabilities of the Russian R-73 missile , but many commentators think this was
3811-591: The "P3I ASRAAM", a version of ASRAAM as a candidate for the AIM-9X program. The ultimate winner was the Hughes submission using the same seeker but with the rocket motor, fuse and warhead of the AIM-9M. The latter was a US Air Force stipulation to ease the logistics burden and save money by reusing as much as possible of the existing AIM-9 Sidewinder, of which 20,000 remained in the US inventory. ASRAAM Block 6 standard, developed under
3914-426: 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
4017-410: 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,
4120-421: 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
4223-436: 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
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4326-471: The AMRAAM than other IR missiles, although it retains high manoeuvrability. To provide the needed power, the ASRAAM is built on a 16.51 cm (6½ inch) diameter rocket motor compared with Sidewinder's (AIM-9M and X) and IRIS-T's 12.7 cm (5-inch) motors (which trace their history to the 1950s unguided Zuni rocket ). This gives the ASRAAM significantly more thrust and therefore increased speed and range up to 50 kilometres (31 mi). The main improvement
4429-628: The ASRAAM Sustainment programme, entered service on the Typhoon in April 2022, and will enter F-35 service in 2024. The Block 6 introduces new and updated sub-systems, and replaces external cooling with a new internal cooler. The original Raytheon seeker has been replaced with a new UK -built seeker of higher resolution. There are no US-made components, meaning that it does not come under ITAR restrictions and can therefore be exported without US approval. At
4532-490: 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
4635-542: The Eurofighter Typhoon in 2018 and on the UK's F-35Bs from 2022 onwards. In February 2017, successful firing of ASRAAMs from F-35 Lightning IIs were conducted at Naval Air Station Patuxent River and Edwards Air Force Base in the USA. This represented the first time that a British-designed missile had been fired from an F-35 JSF and the first time any non-US missile had ever been fired from the aircraft. As of 31 January 2019,
4738-576: 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
4841-569: The Typhoon and F-35B Lightning in RAF and Royal Navy service. Indian Air Force – 384 ASRAAMs for SEPECAT Jaguar strike aircraft fleet. Armed Forces of Ukraine - In August 2023 a surface-launched version of ASRAAM was reported mounted on a Supacat HMT chassis in Ukraine. Royal Australian Air Force - Equipped the F/A-18 A/B Hornet from 2004 until the aircraft's retirement in 2021. The RAAF uses
4944-480: The UK's MoD signed a £300 million contract for a new and improved version of the ASRAAM that would leverage new technological developments, including those from the CAMM missile. This variant would replace the current one when it goes out of service in 2022. A further £184 million contract was awarded in August 2016 to provide additional stocks of the new ASRAAM for the UK's F-35B. This new variant will be operationally ready on
5047-464: 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
5150-477: 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
5253-410: 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
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#17328450990785356-451: 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
5459-409: 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,
5562-478: 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
5665-401: 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
5768-472: 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
5871-401: 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
5974-401: 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
6077-410: 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
6180-401: 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
6283-438: 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
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#17328450990786386-433: 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
6489-494: 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
6592-583: 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
6695-402: 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
6798-528: The great range disparity between the Sidewinder and the AMRAAM. Germany left the programme in 1989. The British proceeded on their own and the missile was introduced into RAF service in 1998. It is being introduced to the Indian Air Force , the Qatar Air Force and the Royal Air Force of Oman , and formerly saw service in the Royal Australian Air Force . The ASRAAM is also the base design for
6901-403: 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
7004-538: The infrared wavelengths of light compared to objects in 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
7107-413: 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
7210-439: The markings on the reticle. At this same instant, a spin-scan system would be producing a constant output in its center null. Flares will still be seen by the con-scan seeker and cause confusion, but they will no longer overwhelm the target signal as it does in the case of spin-scan when the flare leaves the null point. Lock-on after launch Lock-on after launch ( LOAL ) is the ability of missile systems to lock-on to
7313-555: 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
7416-456: 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
7519-399: 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
7622-659: The new ASRAAM, the French MICA and a new design from Bodensee Gerätetechnik, their version of the ASRAAM tuned for German needs. In 1992 the Ministry of Defence announced that ASRAAM had won the contest, and production began in March that year. The German design, by now part of Diehl BGT Defence , became the IRIS-T . While ASRAAM was entering production, momentum behind US-led industrial and political lobbying grew significantly and, combined with
7725-469: 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
7828-469: 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
7931-487: 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
8034-428: 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
8137-406: 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
8240-421: 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
8343-410: 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
8446-593: 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
8549-549: 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
8652-527: 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
8755-461: 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
8858-615: 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
8961-403: 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
9064-410: 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
9167-405: 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
9270-576: 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
9373-507: The strengthening European economy, forced the US government to conclude testing in June 1996 and move away from the ASRAAM program. UK development and manufacture went ahead and the first ASRAAM was delivered to the Royal Air Force (RAF) in late 1998. It equips the RAF's Typhoon . It was also used by the RAF's Harrier GR7 and Tornado GR4 forces until their retirement. In February 1998 ASRAAM
9476-407: 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
9579-483: 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,
9682-465: 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
9785-414: 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
9888-485: 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
9991-432: 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
10094-412: 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
10197-582: 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
10300-407: 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
10403-518: 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
10506-586: Was selected by the Royal Australian Air Force (RAAF) for use on their F/A-18 Hornets following competitive evaluation of the improved ASRAAM, the Rafael Python 4 and the AIM-9X, and entered RAAF service in August 2004. In March 2009 the RAAF successfully carried out the first in-service " Lock-on after launch " firing of an ASRAAM at a target located behind the wing-line of the "shooter" aircraft. ASRAAM
10609-564: 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
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