An air-to-air missile (AAM) is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fueled but sometimes liquid fueled. Ramjet engines, as used on the Meteor, are emerging as propulsion that will enable future medium-range missiles to maintain higher average speed across their engagement envelope.
Air-to-air missiles are broadly put in two groups. Those designed to engage opposing aircraft at ranges of less than 16 km are known as short-range or "within visual range" missiles (SRAAMs or WVRAAMs) and are sometimes called "dogfight" missiles because they are designed to optimize their agility rather than range. Most use infrared guidance and are called heat-seeking missiles. In contrast, medium- or long-range missiles (MRAAMs or LRAAMs), which both fall under the category of beyond visual range missiles (BVRAAMs), tend to rely upon radar guidance, of which there are many forms. Some modern ones use inertial guidance and/or "mid-course updates" to get the missile close enough to use an active homing sensor. The concepts of air-to-air missiles and surface-to-air missiles are very closely related, and in some cases versions of the same weapon may be used for both roles, such as the ASRAAM and Sea Ceptor.
The air-to-air missile grew out of the unguided air-to-air rockets used during the First World War. Le Prieur rockets were sometimes attached to the struts of biplanes and fired electrically, usually against observation balloons, by such early pilots as Albert Ball and A. M. Walters.Facing the Allied air superiority, Germany in World War II invested limited effort into missile research, initially adapting the projectile of the unguided 21 cm Nebelwerfer 42 infantry barrage rocket system into the air-launched BR 21 anti-aircraft rocket in 1943; leading to the deployment of the R4M unguided rocket and the development of various guided missile prototypes such as the Ruhrstahl X-4.
Post-war research led the Royal Air Force to introduce Fairey Fireflash into service in 1955 but their results were unsuccessful. The US Navy and US Air Force began equipping guided missiles in 1956, deploying the USAF's AIM-4 Falcon and the USN's AIM-7 Sparrow and AIM-9 Sidewinder. The Soviet Air Force introduced its K-5 (missile) into service in 1957. As missile systems have continued to advance, modern air warfare consists almost entirely of missile firing. The use of Beyond Visual Range combat became so pervasive in the US that early F-4 variants were armed only with missiles in the 1960s. High casualty rates during the Vietnam War caused the US to reintroduce autocannon and traditional dogfighting tactics but the missile remains the primary weapon in air combat.
In the Falklands War British Harriers, using AIM-9L missiles were able to defeat faster Argentinian opponents.Since the late 20th century all-aspect heat-seeking designs can lock-on to a target from various angles, not just from behind, where the heat signature from the engines is strongest. Other types rely on radar guidance (either on-board or "painted" by the launching aircraft).
A conventional explosive blast warhead, fragmentation warhead, or continuous rod warhead (or a combination of any of those three warhead types) is typically used in the attempt to disable or destroy the target aircraft. Warheads are typically detonated by a proximity fuze or by an impact fuze if it scores a direct hit. Less commonly, nuclear warheads have been mounted on a small number of air-to-air missile types (such as the AIM-26 Falcon) although these are not known to have ever been used in combat.
Guided missiles operate by detecting their target (usually by either radar or infrared methods, although rarely others such as laser guidance or optical tracking), and then "homing" in on the target on a collision course.
Although the missile may use radar or infra-red guidance to home on the target, the launching aircraft may detect and track the target before launch by other means. Infra-red guided missiles can be "slaved" to an attack radar in order to find the target and radar-guided missiles can be launched at targets detected visually or via an infra-red search and track (IRST) system, although they may require the attack radar to illuminate the target during part or all of the missile interception itself.
Radar guidance is normally used for medium- or long-range missiles, where the infra-red signature of the target would be too faint for an infra-red detector to track. There are three major types of radar-guided missile – active, semi-active, and passive.
Radar-guided missiles can be countered by rapid maneuvering (which may result in them "breaking lock", or may cause them to overshoot), deploying chaff or using electronic counter-measures.
Active radar (AR)-guided missiles carry their own radar system to detect and track their target. However, the size of the radar antenna is limited by the small diameter of missiles, limiting its range which typically means such missiles are launched at a predicted future location of the target, often relying on separate guidance systems such as Global Positioning System, inertial guidance, or a mid-course update from either the launching aircraft or other system that can communicate with the missile to get the missile close to the target. At a predetermined point (frequently based on time since launch or arrival near the predicted target location) the missile's radar system is activated (the missile is said to "go active"), and the missile then homes in on the target.
If the range from the attacking aircraft to the target is within the range of the missile's radar system, the missile can "go active" immediately upon launch.
The great advantage of an active radar homing system is that it enables a "fire-and-forget" mode of attack, where the attacking aircraft is free to pursue other targets or escape the area after launching the missile.
Semi-active radar homing (SARH) guided missiles are simpler and more common. They function by detecting radar energy reflected from the target. The radar energy is emitted from the launching aircraft's own radar system.
However, this means that the launch aircraft has to maintain a "lock" on the target (keep illuminating the target aircraft with its own radar) until the missile makes the interception. This limits the attacking aircraft's ability to maneuver, which may be necessary should threats to the attacking aircraft appear.
An advantage of SARH-guided missiles is that they are homing on the reflected radar signal, so accuracy actually increases as the missile gets closer because the reflection comes from a "point source": the target. Against this, if there are multiple targets, each will be reflecting the same radar signal and the missile may become confused as to which target is its intended victim. The missile may well be unable to pick a specific target and fly through a formation without passing within lethal range of any specific aircraft. Newer missiles have logic circuits in their guidance systems to help prevent this problem.
At the same time, jamming the missile lock-on is easier because the launching aircraft is further from the target than the missile, so the radar signal has to travel further and is greatly attenuated over the distance. This means that the missile may be jammed or "spoofed" by countermeasures whose signals grow stronger as the missile gets closer. One counter to this is a "home on jam" capability in the missile that allows it to home in on the jamming signal.
An early form of radar guidance was "beam-riding" (BR). In this method, the attacking aircraft directs a narrow beam of radar energy at the target. The air-to-air missile was launched into the beam, where sensors on the aft of the missile controlled the missile, keeping it within the beam. So long as the beam was kept on the target aircraft, the missile would ride the beam until making the interception.
While conceptually simple, the move is hard because of the challenge of simultaneously keeping the beam solidly on the target (which couldn't be relied upon to cooperate by flying straight and level), continuing to fly one's own aircraft, and monitoring enemy countermeasures.
An added complication was that the beam will spread out into a cone shape as the distance from the attacking aircraft increases. This will result in less accuracy for the missile because the beam may actually be larger than the target aircraft when the missile arrives. The missile could be securely within the beam but still not be close enough to destroy the target.
Infrared guided (IR) missiles home on the heat produced by an aircraft. Early infra-red detectors had poor sensitivity, so could only track the hot exhaust pipes of an aircraft. This meant an attacking aircraft had to maneuver to a position behind its target before it could fire an infra-red guided missile. This also limited the range of the missile as the infra-red signature soon become too small to detect with increasing distance and after launch the missile was playing "catch-up" with its target. Early infrared seekers were unusable in clouds or rain (which is still a limitation to some degree) and could be distracted by the sun, a reflection of the sun off of a cloud or ground object, or any other "hot" object within its view.
More modern infra-red guided missiles can detect the heat of an aircraft's skin, warmed by the friction of airflow, in addition to the fainter heat signature of the engine when the aircraft is seen from the side or head-on. This, combined with greater maneuverability, gives them an "all-aspect" capability, and an attacking aircraft no longer had to be behind its target to fire. Although launching from behind the target increases the probability of a hit, the launching aircraft usually has to be closer to the target in such a tail-chase engagement.
An aircraft can defend against infra-red missiles by dropping flares that are hotter than the aircraft, so the missile homes in on the brighter, hotter target. In turn, IR missiles may employ filters to enable it to ignore targets whose temperature is not within a specified range.
Towed decoys which closely mimic engine heat and infra-red jammers can also be used. Some large aircraft and many combat helicopters make use of so-called "hot brick" infra-red jammers, typically mounted near the engines. Current research is developing laser devices which can spoof or destroy the guidance systems of infra-red guided missiles. See Infrared countermeasure.
Start of the 21st century missiles such as the ASRAAM use an "imaging infrared" seeker which "sees" the target (much like a digital video camera), and can distinguish between an aircraft and a point heat source such as a flare. They also feature a very wide detection angle, so the attacking aircraft does not have to be pointing straight at the target for the missile to lock on. The pilot can use a helmet mounted sight (HMS) and target another aircraft by looking at it, and then firing. This is called "off-boresight" launch. For example, the Russian Su-27 is equipped with an infra-red search and track (IRST) system with laser rangefinder for its HMS-aimed missiles.
A recent advancement in missile guidance is electro-optical imaging. The Israeli Python-5 has an electro-optical seeker that scans designated area for targets via optical imaging. Once a target is acquired, the missile will lock-on to it for the kill. Electro-optical seekers can be programmed to target vital area of an aircraft, such as the cockpit. Since it does not depend on the target aircraft's heat signature, it can be used against low-heat targets such as UAVs and cruise missiles. However, clouds can get in the way of electro-optical sensors.
Evolving missile guidance designs are converting the anti-radiation missile (ARM) design, pioneered during Vietnam and used to home in against emitting surface-to-air missile (SAM) sites, to an air intercept weapon. Current air-to-air passive anti-radiation missile development is thought to be a countermeasure to airborne early warning and control (AEW&C - also known as AEW or AWACS) aircraft which typically mount powerful search radars.
Due to their dependence on target aircraft radar emissions, when used against fighter aircraft passive anti-radiation missiles are primarily limited to forward-aspect intercept geometry.For examples, see Vympel R-27 and Brazo.
Another aspect of passive anti-radiation homing is the "home on jam" mode which, when installed, allows a radar-guided missile to home in on the jammer of the target aircraft if the primary seeker is jammed by the electronic countermeasures of the target aircraft
Air-to-air missiles are typically long, thin cylinders in order to reduce their cross section and thus minimize drag at the high speeds at which they travel. Missiles are divided into five primary systems (moving forward to aft): seeker, guidance, warhead, rocket motor, and control actuation.
At the front is the seeker, either a radar system, radar homer, or infra-red detector. Behind that lies the avionics which control the missile. Typically after that, in the centre of the missile, is the warhead, usually several kilograms of high explosive surrounded by metal that fragments on detonation (or in some cases, pre-fragmented metal).
The rear part of the missile contains the propulsion system, usually a rocket of some type and the control actuation system or CAS. Dual-thrust solid-fuel rockets are common, but some longer-range missiles use liquid-fuel motors that can "throttle" to extend their range and preserve fuel for energy-intensive final maneuvering. Some solid-fuelled missiles mimic this technique with a second rocket motor which burns during the terminal homing phase. There are missiles in development, such as the MBDA Meteor, that "breathe" air (using a ramjet, similar to a jet engine) in order to extend their range.
Modern missiles use "low-smoke" motors – early missiles produced thick smoke trails, which were easily seen by the crew of the target aircraft alerting them to the attack and helping them determine how to evade it.
The CAS is typically an electro-mechanical, servo control actuation system, which takes input from the guidance system and manipulates the airfoils or fins at the rear of the missile that guide or steers the weapon to target.
A missile is subject to a minimum range, before which it cannot maneuver effectively. In order to maneuver sufficiently from a poor launch angle at short ranges to hit its target, some missiles use thrust vectoring, which allow the missile to start turning "off the rail", before its motor has accelerated it up to high enough speeds for its small aerodynamic surfaces to be useful.
A number of terms frequently crop up in discussions of air-to-air missile performance.
Short-range air-to-air missiles used in "dogfighting" are usually classified into five "generations" according to the historical technological advances. Most of these advances were in infrared seeker technology (later combined with digital signal processing).
Early short-range missiles such as the early Sidewinders and K-13 (missile) (AA-2 Atoll) had infrared seekers with a narrow (30-degree) field of view and required the attacker to position himself behind the target (rear aspect engagement). This meant that the target aircraft only had to perform a slight turn to move outside the missile seeker's field of view and cause the missile to lose track of the target ("break lock").
Second-generation missiles utilized more effective seekers that improved the field of view to 45 degrees.
This generation introduced "all aspect" missiles, because more sensitive seekers allowed the attacker to fire at a target which was side-on to itself, i.e. from all aspects not just the rear. This meant that while the field-of-view was still restricted to a fairly narrow cone, the attack at least did not have to be behind the target.
The R-73 (missile) (AA-11 Archer) entered service in 1985 and marked a new generation of dogfight missile. It had a wider field of view and could be cued onto a target using a helmet mounted sight. This allowed it to be launched at targets that would otherwise not be seen by older generation missiles that generally stared forward while waiting to be launched. This capability, combined with a more powerful motor that allows the missile to maneuver against crossing targets and launch at greater ranges, gives the launching aircraft improved tactical freedom.
Other members of the 4th generation use focal plane arrays to offer greatly improved scanning and countermeasures resistance (especially against flares). These missiles are also much more agile, some by employing thrust vectoring (typically gimballed thrust).
The latest generation of short-range missiles again defined by advances in seeker technologies, this time electro-optical imaging infrared (IIR) seekers that allow the missiles to "see" images rather than single "points" of infrared radiation (heat). The sensors combined with more powerful digital signal processing provide the following benefits:
Examples of fifth-generation missiles include:
For each missile, short notes are given, including an indication of its range and guidance mechanism.
|Weight||Rocket Name||Country of origin||Period of manufacture and use||Warhead weight||Warhead types||Range||Speed|
|43.5 kg||Molniya R-60|| Soviet Union |
|1974-||3 kg||expanding-rod warhead||8 km||Mach 2.7|
|82.7 kg||K-5|| Soviet Union |
|1957-1977||13 kg||High explosive warhead||2–6 km||Mach 2.33|
|86 kg||Raytheon AIM-9 Sidewinder||United States||1956-||9.4 kg||Annular blast fragmentation||18 km||Mach 2.5|
|87.4 kg||Diehl IRIS-T||Germany||2005-||11.4 kg||HE/fragmentation||25 km||Mach 3|
|88 kg||MBDA AIM-132 ASRAAM||United Kingdom||2002-||10 kg||Blast/fragmentation||25 km||Mach 3+|
|89 kg||Matra R550 Magic/Magic 2||France||1976-1986 (Magic)|
1986- (Magic 2)
|12.5 kg||Blast/fragmentation||20 km||Mach 2.7|
|105 kg||Vympel R-73||Russia||1982-||7.4 kg||Fragmentation||20–40 km||Mach 2.5|
|112 kg||MBDA MICA-EM/-IR||France||1996- (EM)|
(focused splinters HE)
|> 60 km||Mach 4|
|118 kg||Rafael Derby||Israel||1990-||23 kg||Blast/fragmentation||50 km||Mach 4|
|136 kg||de Havilland Firestreak||United Kingdom||1957-1988||22.7 kg||Annular Blast Fragmentation||6.4 km||Mach 3|
|152 kg||Raytheon AIM-120D AMRAAM||United States||2008||18 kg||Blast/fragmentation||>160 km||Mach 4|
|152 kg||Raytheon AIM-120C AMRAAM||United States||1996||18 kg||Blast/fragmentation||>105 km||Mach 4|
|152 kg||Raytheon AIM-120B AMRAAM||United States||1994-||23 kg||Blast/fragmentation||55-75 km||Mach 4|
|154 kg||Hawker Siddeley Red Top||United Kingdom||1964-1988||31 kg||Annular Blast Fragmentation||12 km||Mach 3.2|
|154 kg||Astra Missile||India||2010-||15 kg||HE fragmentation directional warhead||20 km||Mach 4.5+|
|175 kg||Vympel R-77||Russia||1994-||22 kg||Blast/fragmentation||80-160 km||Mach 4.5|
|180 kg||PL-12||China||2007-||?||?||70-100 km||Mach 4|
|190 kg||MBDA Meteor||United Kingdom Europe||2016-||?||Blast/fragmentation||200 km||Mach 4+|
|220 kg||AAM-4||Japan||1999-||?||Directional explosive warhead||100-120 km||Mach 4-5|
|230 kg||AIM-7 Sparrow||United States||1959-1982||40 kg||High explosive blast-fragmentation||22-85 km||Mach 2.5-4|
|253 kg||R-27|| Soviet Union |
|1983–||39 kg||Blast/fragmentation, or continuous rod||40–170 km||Mach 4.5|
|450–470 kg||AIM-54 Phoenix||United States||1974–2004||61 kg||High explosive||190 km||Mach 5|
|475 kg||R-40|| Soviet Union |
|1970-||38–100 kg||Blast fragmentation||50–80 km||Mach 2.2-4.5|
|490 kg||R-33|| Soviet Union |
|1981-||47.5 kg||HE/fragmentation warhead||120-220 km||Mach 4.5-6|
|600 kg||R-37|| Soviet Union |
|1989-||60 kg||HE fragmentation directional warhead||150-398 km||Mach 6|
|748 kg||K-100||Russia/ India||2010-||50 kg||HE fragmentation directional warhead||200-400 km||Mach 3.3|
The AIM-7 Sparrow is an American, medium-range semi-active radar homing air-to-air missile operated by the United States Air Force, United States Navy, and United States Marine Corps, as well as other various air forces and navies. Sparrow and its derivatives were the West's principal beyond visual range (BVR) air-to-air missile from the late 1950s until the 1990s. It remains in service, although it is being phased out in aviation applications in favor of the more advanced AIM-120 AMRAAM.
The IRIS-T is a German-led program to develop a short to medium range infrared homing air-to-air missile to replace the AIM-9 Sidewinder found in some NATO member countries. Any aircraft capable of firing the Sidewinder is also capable of launching the IRIS-T.
Semi-active radar homing (SARH) is a common type of missile guidance system, perhaps the most common type for longer-range air-to-air and surface-to-air missile systems. The name refers to the fact that the missile itself is only a passive detector of a radar signal—provided by an external ("offboard") source—as it reflects off the target. Semi-active missile systems use bistatic continuous-wave radar.
The Vympel NPO R-77 missile is a Russian active radar homing beyond-visual-range air-to-air missile. It is also known by its export designation RVV-AE. It is the Russian counterpart to the American AIM-120 AMRAAM missile.
The Kaliningrad K-8 (R-8) was a medium-range air-to-air missile developed by the Soviet Union for interceptor aircraft use.
The Vympel K-13 is a short-range, infrared homing air-to-air missile developed by the Soviet Union. It is similar in appearance and function to the American AIM-9B Sidewinder from which it was reverse-engineered. Although it since has been replaced by more modern missiles in frontline service, it saw widespread service in many nations.
The MolniyaR-60 is a short-range lightweight infrared homing air-to-air missile designed for use by Soviet fighter aircraft. It has been widely exported, and remains in service with the CIS and many other nations.
Fire-and-forget is a type of missile guidance which does not require further external intervention after launch such as illumination of the target or wire guidance, and can hit its target without the launcher being in line-of-sight of the target. This is an important property for a guided weapon to have, since a person or vehicle that lingers near the target to guide the missile is vulnerable to attack and unable to carry out other tasks.
The Hughes AIM-4 Falcon was the first operational guided air-to-air missile of the United States Air Force. Development began in 1946; the weapon was first tested in 1949. The missile entered service with the USAF in 1956.
The BisnovatR-4 was an early Soviet long-range air-to-air missile. It was used primarily as the sole weapon of the Tupolev Tu-128 interceptor, matching its RP-S Smerch ('Tornado') radar.
The BisnovatR-40 is a long-range air-to-air missile developed in the 1960s by the Soviet Union specifically for the MiG-25P interceptor, but can also be carried by the later MiG-31. It is the largest air-to-air missile in the world ever to go into production.
The R-33 is a long-range air-to-air missile developed by Vympel. It is the primary armament of the MiG-31 interceptor, intended to attack large high-speed targets such as the SR-71 Blackbird, the B-1 Lancer bomber, and the B-52 Stratofortress.
The Vympel R-23 is a medium-range air-to-air missile developed by Vympel in the Soviet Union for fighter aircraft. An updated version with greater range, the R-24, replaced it in service. It is comparable to the American AIM-7 Sparrow, both in terms of overall performance as well as role.
The Vympel R-27 is a family of air-to-air missile developed by the Soviet Union. It remains in service with the Russian Air Force, air forces of the Commonwealth of Independent States and air forces of many other countries as standard medium range air-to-air missile even though they have the more advanced R-77.
A beyond-visual-range missile (BVR) is an air-to-air missile (BVRAAM) that is capable of engaging at ranges of 20 nmi (37 km) or beyond. This range has been achieved using dual pulse rocket motors or booster rocket motor and ramjet sustainer motor.
Active radar homing (ARH) is a missile guidance method in which a missile contains a radar transceiver and the electronics necessary for it to find and track its target autonomously. The NATO brevity code for an air-to-air active radar homing missile launch is fox three.
The AIM-152 AAAM was a long-range air-to-air missile developed by the United States. The program went through a protracted development stage but was never adopted by the United States Navy, due to the ending of the Cold War and the reduction in threat of its perceived primary target, Soviet supersonic bombers. Development was cancelled in 1992.
The Mitsubishi AAM-4 is a medium-range active radar homing air-to-air missile, considered as modern beyond-visual-range missile developed in Japan and intended to replace the semi-active radar homing AIM-7 Sparrow missile in service. It has been operational since 1999. The main contractor is Mitsubishi Electric. The 2010 AAM-4B was the world's first air-to-air missile with an AESA radar seeker.
The PL-2 is an infrared homing (IRH) air-to-air missiles (AAM) developed in the People's Republic of China (PRC). It was a reverse-engineered Soviet Vympel K-13, which in turn was a reverse-engineered American AIM-9B Sidewinder.
In the field of weaponry, terminal guidance refers to any guidance system that is primarily or solely active during the "terminal phase", just before the weapon impacts its target. The term is generally used in reference to missile guidance systems, and specifically to missiles that use more than one guidance system through the missile's flight.