Check Six – 360º Air Engagements

Lockheed Martin F-35B
A Lockheed Martin F-35B fires the last Flight Sciences separation test of an AIM-132 ASRAAM.

Air-to-air missiles can engage targets beyond visual range and ‘over the shoulder.’

The development of fighter aircraft has largely stalled in recent years, at least in terms of aircraft performance. Development has been largely focused on systems including sensors, avionics, displays, the ‘man machine interface’, and electronic warfare (EW) equipment, as well as the technologies behind Low Observability (LO) or ‘stealth’.

Weapons development has largely been concentrated on precision air-to-ground weapons, and until relatively recently, and with a few notable exceptions, most of the world’s air-to-air weapons would have been familiar to fighter pilots from 25 years ago!

The leading short-range weapons then included the AIM-9 Sidewinder, in its Falklands War-winning AIM-9L form, or in the shape of the later AIM-9M, and the Russian R-73/74 AA-11 ‘Archer’, while older missiles remained in use in some numbers. Generally speaking (and excepting the R-73 and its variants), short range missiles required the launch aircraft to point its nose at the target, framing it in the head up display, allowing the missile seeker to acquire the IR source presented by the enemy aircraft in order to lock on. When this was achieved, the pilot would hear a confirmatory tone or ‘growl’ in his headphones, and would launch a missile, reasonably sure that it would then close in on the target and either explode on impact, or when triggered by a proximity fuse. The big leap in capability had been the development of ‘all aspect’ missiles, which could be fired at a crossing target or even a head on target, and that did not need to be pointed directly up an enemy aircraft’s jet-pipe in order to acquire it.

But that has all changed in more recent times, and today the fighter pilot expects to be able to engage a target far outside the narrow confines of his head up display, perhaps using a helmet mounted sight, or helmet mounted cueing system to ‘point’ the seeker head of his missile at a target somewhere off his wingtip – or even behind him.

Though the South Africans (and then the Russians) pioneered the use of missiles that could be fired at high off boresight angles, as long ago as the 1970s, cued by the use of helmet mounted sights, this technology has only recently become really widely adopted.

Apartheid South Africa’s isolation led to the development of a succession of advanced IR-homing air-to-air missiles, culminating in the A-Darter (V3E), which was given a formal Type Certificate by South Africa and Brazil in September 2019, and which has been cleared for use on the Saab JAS39 Gripen. The A-Darter has a thrust vectoring control (TVC) system, and a two colour thermal imaging seeker. The weapon has a range of 12 nautical miles (22km), and the absence of aluminium powder in the propellent inhibits production of a smoke trail.

Rafael’s Python 5 marks the latest in a series of Israeli air-to-air missiles. The missile has 18 control surfaces, which are claimed to make the weapon at least as agile as rival missiles with thrust vectoring. The advanced seeker includes an electro-optical (EO) and image infrared (IR) homing seeker which scans the target area for hostile aircraft, then locks-on for terminal chase. Python 5 has a range of 10nm (20 km) and carries an 24 pound (11 kilogram) warhead.

Rafael’s Python 5
Rafael’s Python 5 air-to-air missile has 18 control surfaces which gives the missile its agility.

Arguably the most interesting WVR missiles on the market today resulted from the same requirement! In the 1980s, North Atlantic Treaty Organisation (NATO) nations signed a Memorandum of Agreement (MoA) under which the United States (US) would develop the AMRAAM for beyond visual range (BVR) use, while European countries abandoned their medium range missile programmes. The quid pro quo was that an Anglo-German team would develop a short-range air-to-air missile to replace the AIM-9 Sidewinder. But in the end, the US and Germany would drop out of the original ASRAAM programme to develop their own short-range missiles, while the UK programme gave rise to an entirely new design.

The US developed the AIM-9X, marrying the rocket motor, fusing system, and warhead, from the AIM-9M to a new focal-plane array (FPA) seeker, a digital autopilot, fixed forward canards, with steerable tail surfaces and three-dimensional thrust vectoring. The Focal Plane Array had been designed by BAE Dynamics for ASRAAM, but was due to have been manufactured by Hughes in the US. The AIM-9X’s lower drag gives it improved range and speed than its predecessors, with a claimed range of 19nm (35km). Some 13 separation and control test launches and 12 guided launches were performed from US Navy Boeing F/A-18s and USAF Boeing F-15s between 1999 and 2000, leading to a first low-rate initial production contract for the AIM-9X in November 2000 and initial operational capability (IOC) in November 2003.

F-16 Fighting Falcon
An F-16 Fighting Falcon from the 49th Wing at Holloman Air Force Base, N.M., fires an AIM-9M Sidewinder during training and evaluation at Weapons System Evaluation Program-East, 10 March, 2021.

The AIM-9X Block II missile was an upgraded variant with a new datalink and a lock-on-after-launch capability, and this entered service in 2015. The AIM-9X is claimed to have improved infrared counter counter measures (IRCCM) performance but has apparently had some difficulty with older Soviet-era flares. When a US Navy F/A-18E Super Hornet strike fighter tried to shoot down a Syrian Su-22 ‘Fitter’ the AIM-9X was decoyed, and the F/A-18E had to fire an AIM-120.

Germany withdrew from the ASRAAM project in 1990, after it discovered that the capabilities of the Vympel R-73 missile (the AA-11 ‘Archer’) had been seriously underestimated, and that it was far more capable in terms of seeker acquisition and tracking than the latest AIM-9 Sidewinder. This led Germany to develop a new, tail-controlled, thrust-vectoring missile with a new imaging IR seeker, but which retained the diameter, length, mass and centre of gravity as the AIM-9, ensuring that any aircraft capable of firing the Sidewinder would also be capable of launching the Diehl BGT Defence IRIS-T, using the same missile launcher interface. Slower than many of its competitors, at just Mach 3, IRIS-T had a range of 14nm (25km).

Following the departure of Germany from the ASRAAM consortium, a new version was designed to meet the Royal Air Force’s (RAF’s) specification, with no operational or technical compromises to satisfy the requirements of other customers. BAE received a $786 million (£570 million) development and manufacturing contract in 1992, and a first guided firing was undertaken in the US, in 1996, from an Lockheed Martin F-16 test aircraft.

UK Service Evaluation Trials were flown by the Panavia Tornado F3 OEU, which deployed to Eglin Air Force Base in April 2002. A Tornado F.Mk 3 downed a pair of QF-4 drones in the process.

After some delays, the AIM-132 ASRAAM finally entered service with the RAF in 2002. The introduction of ASRAAM revolutionised RAF air defence capabilities. The revolutionary focal plane array (FPA) seeker allowed targets to be acquired at significant BVR distances, while the high energy motor provided very high acceleration, and gave range performance that was comparable with the last generation of radar-guided BVR missiles. The ASRAAM’s range is usually stated to be ‘in excess of 13nm (25km)’ and has been reported to be as long as 26nm (50km).

AIM-9X Sidewinder missile
USAF airmen prepare the AIM-9X Sidewinder missile before a live fire test at Holloman Air Force Base, New Mexico, in 2019. The AIM-9X is arguably the most advanced infrared-tracking, short-range, air-to-air and surface-to-air missile.

ASRAAM was designed for use against targets at much longer ranges than other IR-homing missiles, responding faster, getting off the rail faster, flying faster and reaching further than any other competing missile, and reaching as far as early versions of the AMRAAM.

To ensure this, ASRAAM used a 6.5 inch (16.51cm) diameter rocket motor. This compared to the 5in (12.7cm) motors used by the AIM-9M and AIM-9X and IRIS-T. This gave the ASRAAM significantly more thrust, speed and range. The weapon frequently defeated targets that tried to break off an engagement, as they were unable to achieve sufficient separation from the launch aircraft to avoid being shot down. ASRAAM also proved able to discriminate easily between decoy flares and real targets. With a full digital integration on the Typhoon, including the use of a helmet-mounted sight, ASRAAM proved even more impressive, demonstrating unmatched high off-bore sight capabilities.

The missile can be fired ‘over-the-shoulder’ to engage a threat behind the launch aircraft, and the target does need not be in the seeker’s field of view at launch because of the midcourse inertial guidance capability. This capability was demonstrated in 2009 by a Royal Australian Air Force (RAAF) F-18, which conducted a successful lock on after launch firing of an ASRAAM at a target behind the wing line, simulating a ‘chase down’ situation by an enemy fighter.

The US refused to share ASRAAM integration data with F-16 operators, hoping to advantage the home-grown AIM-9X. This effectively shut off a potentially huge export market for ASRAAM sales. The RAAF shortlisted ASRAAM for its F/A-18A Hornet fighters in 1997, after evaluating it against the Rafael Python 4 and the AIM-9X, which were judged to be inferior.

A new Block 6 ASRAAM is now in production, incorporating a new generation seeker of increased pixel density, and a new rocket motor, a new intelligent proximity fuze, and a new actuation system from the CAMM air defence missile. The new variant has already been selected and ordered by the Sultanate of Oman and Qatar for their Eurofighter Typhoons, and by India, and further exports are likely.

MBDA inked a $428 million (£250 million) contract to supply 384 missiles to India in July 2014, to equip its upgraded SEPCAT Jaguar fighter-bombers under the ‘New Generation Close Combat Missile’ (NGCCM) programme. The ASRAAM is also set to equip India’s Sukhoi Su-30MKI squadrons, and the indigenous Light Combat Aircraft (LCA).

The IRIS-T configuration is shared by the Japanese AAM-5B, which entered service in 2004, though exports are unlikely, so it remains of little interest outside the JASDF! Interestingly, the new Chinese PL-10 also uses the same basic configuration, and this weapon has been claimed to be China’s most advanced air to air missile. A prototype was reportedly completed in 2013, and the weapon has been tested on the stealthy J-20 and on the J-11 (a licence-built Su-27). On the J-20 the weapon can move from its internal weapons bay to a semi-external position, with weapons bay doors closing behind it to give the seeker a view of the outside world, while minimising radar returns from the weapon bay itself. The PL-10 should not be assumed to be an IRIS-T copy, though previous Chinese AAMs have often been copies of Western designs.

IRIS-T missile
A Swedish Air Force Gripen E test firing a Diehl BGT Defence IRIS-T missile.

Interestingly, France followed a very different approach in developing its MICA (Missile d’interception, de combat et d’autodéfense, ‘interception, combat and self-defence missile’), producing a longer-range weapon for use over both short and medium ranges. MICA was developed by Matra from 1982, with the French company subsequently becoming part of the Anglo French MBDA. Flight trials began in 1991, and the missile was ordered in 1996 to equip the Dassault Rafale and Mirage 2000.

MICA is available in two versions – the MICA RF with an active radar homing seeker and the MICA IR with an imaging infra-red homing seeker. The intention was to provide a missile that would replace both the ‘French Sparrow’ – the Matra Super 530 – in the BVR intercept role but also the shorter-range Matra Magic II IR-homing dogfight missile. The weapon was the first Western air-to-air missile to use thrust vectoring but it is neither as agile as some competing IR-homing rivals nor as fast and as lethal as other BVR weapons, but it does represent an interesting, effective and useful compromise.

MICA is not yet believed to have a mature integration with a helmet cueing system, but has demonstrated a third-party targeting capability, undertaking a ‘Parthian’ over-the-shoulder shot against a pursuing target.

MBDA MICA fired from a Rafale.

There is a new generation of short-range ‘dogfight’ missiles now under development, not least in the US, where the USAF has sponsored two separate research and development programmes by Raytheon: the Small Advanced Capability Missile (SACM) and Miniature Self-Defense Munition (MSDM). Lockheed Martin has also designed a conceptual air-to-air missile known as Cuda, and nicknamed ‘Halfraam’, which promises to double the F-22’s missile load, and to provide a short-to-medium range weapon.

In recent concept artwork portraying a number of future fighter programmes, tomorrow’s fighters have been shown using directed energy weapons against other aircraft. But these weapons remain essentially unproven, and despite decades of research and development, they are still at the experimental stage. They are likely to demand huge amounts of electrical power and are liable to have only the most modest range. The air-to-air missile looks like it will be here to stay – at least for the foreseeable future.

by Jon Lake