27th Oct 2011 By Jean-Michel Guhl in Cazaux, France - defencereviewasia.com
ONE of the most present and most concealed threats on the battlefield remains the shoulder-launched surface to air missile or Manpads – an abbreviation of man-portable air defence system. A light affordable and plentiful weapon with a low acquisition cost, it is also a war tool that outweighs by multiples the price of its likely target - a tactical fighter plane, helicopter or even a multi-engined airlifter. Intended for air defence by the military, Manpads have also unfortunately over the years landed in the hands of uncontrolled groups or terrorist organisations, accounting for some dramatic deadly attacks on civilian transport aircraft as well.
ONE of the most present and most concealed threats on the battlefield remains the shoulder-launched surface to air missile or Manpads – an abbreviation of man-portable air defence system. A light affordable and plentiful weapon with a low acquisition cost, it is also a war tool that outweighs by multiples the price of its likely target - a tactical fighter plane, helicopter or even a multi-engined airlifter. Intended for air defence by the military, Manpads have also unfortunately over the years landed in the hands of uncontrolled groups or terrorist organisations, accounting for some dramatic deadly attacks on civilian transport aircraft as well.
During the Soviet war in Afghanistan (1979-1989), thousands of US-made FIM-92 Stinger shoulder-launched missiles were supplied, by the CIA via Pakistan, to the Mujahideen, along with British-made Blowpipes, older US FIM-43 Redeyes, and even Egyptian (Ayn-as-Sakr - Falcon Eye) and Chinese (HN-5) copies of the infamous Soviet 9K32M Strela (NATO SA-7b) Manpads!
These 10-kg missiles, capable of reaching Mach 2 in 5 seconds and with an average lethal range of just a few kilometres, were responsible for the destruction of many Soviet airlifters, as well as transport and attack helicopters. Only dedicated “shturmovik” fighter-bombers like the Su-25 “Frogfoot” and Su-22 “Fitter” fared much better, in general, thanks to their extremely sturdy airframe construction. From experience gained in that war and in peacetime exercises prior to 1994, the Soviets found that the best way for a group of gunships to survive their own attack run was to fly at extremely low altitudes towards the target and then split up, approaching it from different directions. After making their attacks, the helicopters would make a break-off turn and depart at extremely low altitudes, their wingmen providing mutual covering fire and all of them making full use of their electronic warfare equipment (decoy flares and IR jammers). Most of these techniques have also been adopted in the West. Just as a reminder: 333 airplanes and helicopters were lost by the Soviets to Manpads during their war 25 years ago.
Combating the Manpads threat has gained in importance in recent times with the use of countermeasures using various techniques. IRCM systems are designed to defeat both surface-to-air and air-to-air missiles by detecting the ultraviolet (UV) or infrared (IR) radiation from the missile exhaust trail and then initiating responses. Counter-measures include both flares – which are designed to give the missile a decoy target – and laser jammers – which cause missile guidance systems to abruptly steer away from the target aircraft.
In order to tackle the lingering Manpads menace as a whole, and with the Soviet tactical experience in mind, NATO has been organising every other year in Europe, since 1991, a series of two live exercises designated MACE and Embow. If MACE caters in priority with more expensive electromagnetic (EM) self-defence systems, Embow focuses only on ways to counter heat-seeking (IR) missiles fired from the ground.
Embow XIII in Cazaux air base
A total of sixteen nations participated in the 13th venue of Embow in 2011. The event took place at Cazaux, in France, and saw the attendance of participants from: Belgium, Canada, the Czech Republic, Denmark, Germany, Italy, Norway, France, the Netherlands, Poland, Spain, Turkey, UK, US, with Australia and New Zealand joining as longtime faithful allies of NATO from “down-under”. Aircraft involved were varied, ranging from fighter-bombers to attack helicopters, and from transport helicopters to big airlifters like the C-130 Hercules.
Orchestrated by NATO’s SG2/Aerospace Capability Group 3 on “Electronic Warfare and Survivability”, the main aim of Embow is to allow aviators to test, under live and monitored conditions, the capacity of their aircraft to evade infrared-guided surface-to-air missiles, from basic Manpads to more advanced surface to air short-range systems (SHORADS). As a cherry on the cake, the Embow trials are always performed in highly instrumented areas so that the participants can take a close look at the actual efficiency of the systems they field. Any noticed discrepancy is then funneled, in a second move, back to the industry for updating and improvements.
Spanning four weeks, from 18 September to 12 October, Embow XIII placed a strong priority on how to enhance or optimise the self-protection systems of NATO aircraft currently participating in overseas expeditionary missions: fighters, airlifters and helicopters alike. True to say, US airplanes and rotorcraft from other NATO nations have paid, since 2002 in Iraq and Afghanistan, a heavy toll to the insurgents, while furthermore ongoing air operations over Libya have proved in combat the value of the different EW systems developed by the European industry for their current generation aircraft.
As such, European manufacturers of electronic warfare equipment took advantage of Embow XIII to test current as well as prototypes of future EW systems during some 100 “live firing” sorties from Cazaux AB performed over the DGA Biscarosse test site and its extensive network of radars and trajectography equipment.
This was particularly the case for EADS Cassidian and the Spanish company Indra who used a CASA 212 test-bed from the French DGA (the French Defence Procurement Agency) to put on trial a new DIRCM designed for the self-protection of high-value transport aircraft. Dubbed Manta, this multi-spectral multi-band high-energy laser-based system (developed in partnership with Rosoboronexport of Russia), is able to counter several Manpads launched simultaneously from short distances. It is intended to equip the A400M at a later stage.
For the Embow XIII evaluation, Indra’s Manta was linked to sensors from Cassidian’s AN/AAR-60 MILDS (Missile Launch Detection System) as used today on many NATO tactical airplanes and helicopters, like the Tiger, Mangusta and Black Hawk.
Burning fires of deception
If the use of chaff (metal foil) in combat dates back to World War 2 – clouds of small metallic dipoles being dropped by attacking bombers to deceive or jam German radars – the use of flares (burning decoys) as counter-measures against heat-seeking missiles is more recent and truly appropriate for the jet age. The ubiquitous Infra-Red Countermeasures
(IRCM) decoy flare is nearly 50 years old. Simple, robust and effective, for many years it was the only means of providing aircraft protection against the IR-guided missile. For today’s flying combat machine, as a matter of fact, chaff and flares are a very common and worthwhile method of evasion against an incoming missile or to disrupt the “lock-on” of a tracking radar.
Initially a US invention – used first in the 1960s on the B-47, B-52 and B-58 strategic bombers aiming to penetrate heavily defended Soviet defence lines – IR flares never saw wide usage during the larger part of the Cold War. Aircraft-mounted self-defence flare launcher systems were first witnessed to be widely used by Israeli aviators over Beirut – particularly noticeable on TV newsreels - during the Lebanon war of 1981 and subsequent air operations against the PLO. Flares were also widely used by the Soviets over Afghanistan a few years later. With the widespread introduction of the SA-7 in 1984 and Stingers in 1985, helicopters became exposed to those missiles, and soon all of them were equipped with flare dispensers, active IR jammers, and exhaust dampers to reduce their infrared (IR) signatures. At first, only Mi-24 “Hind” attack helicopters were so equipped, but eventually Mi-8 “Hip” transports received these counter-measures as well.
In fact, the Israeli Air Force’s brand-new General Dynamics F-16A Block 10 Fighting Falcons were unique in 1981 in being the first Western fighter jets to include the fitting of ALE-40 chaff/flare dispensers – systems for long reserved only for US strategic bombers – to provide an adequate self-protection against heat-seeking missiles. This was based on something the Israelis had learned the hard way during the Yom Kippur war of 1973. An intense conflict where, according to subsequent White House debriefings, the Israeli Air Force lost no less than 102 aircraft – 32 F-4s, 53 A-4s, 11 Mirages and 6 Super Mysteres – mostly to Egyptian and Syrians surface to air missiles. Two helicopters, a Bell 205 and a CH-53, were also shot down this way. In all these cases, the Israeli aircraft were totally devoid of any IR self-defence systems.
What exactly are these IRCM systems? They are in fact a very simple invention, based on canisters bolted to the airframe and firing one or more flaming decoys in sequence in the direction of an incoming infrared-guided missile. IR flares are cartridges usually discharged individually or in salvoes by the pilot (or automatically by a tail-warning system on cue). Usually accompanied by simultaneous vigorous evasive manoeuvering, these decoys are supposed to lure a missile and make them miss them intended target by heading to the decoy’s heat source instead.
Since they are intended to deceive infrared missiles, these flares burn at temperatures of thousands of degrees, incandescing in the visible spectrum as well. They have proved their value repeatedly in combat. Flare decoys are however only effective in the terminal phase acquisition of missiles fitted with IR signature seeker heads, i.e. a very short moment in time, which explains why fully automatic self-defence systems with cued sequencers are now preferred.
Flare decoys are simple inexpensive cigar-sized containers, in general square or round, commonly composed of a pyrotechnic composition based on magnesium or another hot-flaming metal, with burning temperature equal to or hotter than an aircraft engine exhaust. As said, the trick is to make the infrared-guided missile seek out the heat signature from the flare rather than that of the aircraft’s engine(s).
In contrast to electro-magnetically (EM) radar-guided missiles, IR-guided missiles are very difficult to spot as they close on an aircraft. They have no radar signature, and they are generally fired from the rear, directly toward the jet pipe of an aircraft or the hot exhaust of a turbine. In most cases, during combat, pilots have then to rely on their wingmen to spot the missile’s characteristic smoke trail and alert them. Since Manpads are inherently far shorter-legged in distance and altitude range than their radar-guided counterparts, good situational awareness of altitude and potential threats continues to be a very effective defence against them. Luckily, much more advanced electro-optical systems – as developed over the past two decades – can now detect missile launches automatically from the very distinct emissions of a missile’s rocket motor, both in the infrared (IR) and ultra-violet (UV) bands.
How does it work? In flight, once the presence of an IR missile is indicated, flares are released by the aircraft in quick succession in an attempt to decoy the incoming missile; most IRCM systems are automatic, while others – the earlier ones – required manual jettisoning of the flares, thus limiting their efficiency. The aircraft will then pull away at a sharp angle from the flare (and the terminal trajectory of the missile) and reduce engine power in attempt to cool its thermal signature. Optimally, the missile’s seeker head is then confused by this change in temperature and sudden flurry of new hotter signatures, and therefore follows the flare(s) rather than the aircraft… giving the pilot(s) a chance to fight again another day!
For the IR generating cartridges, two approaches are possible: either pyrotechnic or pyrophoric. “As stored”, explains Major Thomas Vermeersch, a test pilot with DGA in Cazaux, “chemical-energy-source IR-decoy flares contain pyrotechnic compositions, pyrophoric substances, and highly flammable substances. Upon ignition of the decoy flare, a strongly exothermal reaction is started, releasing infrared energy and visible smoke and flame, the potency of the emission being dependent on the chemical nature of the payload used.” There are a wide variety of calibres and shapes available for aerial decoy flares depending on their manufacturer. In short, due to volume storage restrictions on-board modern platforms, many aircraft of US origin employ square-shaped cartridges. Cylindrical cartridges (from 19 to 60mm in general) are used mainly on board French aircraft as well as those of Russian origin. They are much more resistant to warping and handing damages.
The coming of DIRCM systems
But in the present day combat theatre, flares are not enough, and new inventions are now being conceived to deceive shoulder-launched infrared missiles. This is especially so with the development of new-generation seekers, dubbed SG4 by NATO, that are now able to discriminate easily between jet pipes and flaming decoys. This aptitude was well demonstrated in a video shown to the press in Cazaux by Isabelle Lecuyer, the person in charge of aircraft self-protection systems with DGA. This revealed that a Mirage 2000D dropping traditional flares could not evade the “lock-on” of a newer generation IR tracker - thus giving the sword a clean edge over the shield…
But new counter-measures are being designed in order to protect aircraft further against the Manpads threat. Among the most promising is the Directional Infrared Counter-Measure system (DIRCM), a solution nowadays principally produced by Northrop Grumman, ITT Corporation and BAE Systems in the USA, and by Elbit Systems in Israel. Thales, Terma, Saab and Indra in Europe are also working on new DIRCMs, as is Russian industry.
More advanced than conventional flare-based IR counter-measure systems, a standard DIRCM is a lightweight, compact system designed to provide mission-vulnerable aircraft – like strategic airlifters and large helicopters – with increased protection from common battlefield IR threats. The term DIRCM is used as a generic moniker to describe any IRCM system that tracks and directs energy toward the menace. Such is the AN/AAQ-24 Nemesis, a DIRCM system which consists of a missile warning system (AN/AAR-54), an integration unit, a processor, and laser turrets (Small Laser Targeting Assembly, SLTA). Early versions used an arc lamp to generate the jamming signal. Newer versions use diode-based pump systems. DIRCMs will be installed as standard on C-17 and MC-130 airlifters, and CV-22 and CH-53E rotorcraft. Nemesis is also the basis for the Northrop Grumman Guardian system marketed for commercial aircraft. Pending the completion of ICAO tests on the viability of such options, they will likely be fitted to many commercial carriers in the near future. So will the Large Aircraft Infrared Counter-Measure system (LAIRCM) and LAIRCM-Lite which is a strict C-17 programme that uses a combination of laser jammers and flares due to the limited availability of some LAIRCM components.
First US try at fooling the IR threat
It took some time for scientists to develop IR countermeasures. By the mid 1960s, an understanding of missile operations and radiation emission from pyrotechnic flames was becoming more mature. As a result, the objectives of new research contracts in the USA became more specific. They undertook the task to develop a pyrotechnic source that radiated in a narrow wavelength band and emitted selectively:
1 - in the specific IR bands resulting from the radiation produced by aircraft;
2 - and capable of operating in the sensitive region of the detector used in the adversary missile guidance system.
The requirement of this effort brought the first attempt to create a pyrotechnic decoy that radiated in regions corresponding to regions where aircraft usually diffuse heat. Today one might identify such a decoy as a “spectral or colour adapted” flare, but in the mid 1960s the researchers did not appreciate how important it would be to have a decoy that would radiate with the proper spectral properties.
In 1967, the US Navy China Lake test centre reported on the development of a decoy flare intended for launching from the AN/ALE-29 dispensing set installed on a number of US military aircraft. The goal was for the flare to defeat the AA-2 “Atoll” short-range, infrared homing air-to-air missile developed by the Soviet Union using the Sidewinder 1A as a surrogate. This was a not too complex issue, in reality, as the “Atoll” (Vympel K-13) was similar in appearance and function to the American AIM-9 Sidewinder (after which it had been reverse-engineered using an unexploded missile recovered in China in September 1958). Early flare developments were aimed at providing protection in the infrared 2m to 3m bandpass region. As missiles improved, the threat moved to also operate in the infrared 3m to 5m bandpass region. In 1968, the US Navy set out to develop a family of infrared flares that were effective in the 3m to 5m bandpass region. They considered changing the combustion mode to a much higher rate, burning more material, lengthening the flare by two inches, altering the AN/ALE-29 dispenser to “squarish” holes, and altering the composition to improve efficiency. The Mk 46 Mod 0 flare, put in production in 1968, was the first US-made flare developed with the above objectives. The need for 120-150 decoy flares on an aircraft operating in a dangerous area was considered mandatory. It was the first time that IRCM investigators suggested that the number of flares that could be carried by aircraft of that era would be insufficient to provide complete protection.
But it took another 10 to 15 years for IRCM systems to become commonplace, and once the Manpads threat turned into a “no escape” lethal issue - something complicated by the use of antiquated weapons like the RPG against low flying aircraft - thus adding more odds in the unending battle between the sword and the shield.
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