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Weapons for whirlybirds.

The development of turbine-engined helicopters in the 1950s brought substantial increases in disposable load, allowing the addition of ground attack weapons, notably machine guns, cannon, rocket projectiles and anti-tank guided weapons. By the 1980s helicopters were also proving their value in the anti-ship role, and there was growing interest in air-to-air missiles, at least for self-defence. Operations over Kosovo in 1999 included the use of gun-armed helicopters to intercept reconnaissance drones.

Although experiments with arming helicopters were carried out during the Korean War (1951 to 1953), operational service began with the introduction of the French Army's turbine-powered Sud-Ouest Alouette II in Algeria in 1958. Dubbed <<le papillon a cornes>> (the horned butterfly), the Alouette II was armed with rifle-calibre machine guns, and later rocket projectiles and SS-10/11 guided missiles. It was employed as an escort in airborne assault and casualty evacuation missions.

Barrels

The objective in arming US Army helicopters in Vietnam in the early 1960s was likewise to provide fire suppression around landing zones, a need in this case brought on by the undependability of South Vietnamese artillery fire and fixed-wing support. The primary weapon for the Bell UH-1 Huey series was the 7.62 mm M60 machine gun, although 70 mm rocket pods were skid-mounted on some aircraft. The M60 was effective to around 700 metres range, but US Army helicopters were soon outgunned by the Vietcong insurgents, who in 1963 introduced the 12.7mm Degtyarev-Shpagin DShKM38/46. This was later augmented by the 14.5 mm KPV-14.5, at that time quite possibly the most powerful machine gun in the world.

The single-barrelled M60 used in the UH-1 was later replaced by the fast-firing, 7.62 mm, six-barrel General Electric M134 Minigun (US Air Force designation GAU-2B/A), although operational losses of helicopters (e.g., during the invasion of Grenada in 1983) indicated that a longer range, heavier calibre weapon was required. The M134 (which began life in 1962) was unique in having a cyclic rate of up to 7200 rounds per minute, but its reliability was poor, although it was also used (three of them) onboard the Puff the Magic Dragon DC-3s. When General Dynamics Armament and Technical Products (GDATP) took over GE's Gatling Gun series, it was decided not to support the M134, the production of which had ceased around 1980. However, Dillon Aero of Arizona has recently formed a division specifically to develop a better M134. The Dillon Aero M134D incorporates a number of design refinements and is restricted to either 3000 or 4000 rds/min, giving a major improvement in reliability.

Soviet use of the Mil Mi-24 in Afghanistan from 1980 to 1987 proved that the turret-mounted, four-barrel, 12.7 mm Yakushev/Borzov YakB-12.7 or 9A624 Gatling Gun lacked adequate range in dealing with well-armed insurgents. It was therefore replaced on the Mi-24P with the twin-barrel 30 mm Gryazev-Shipunov GSh-30 cannon, bolted to the starboard fuselage side. The KBP-developed GSh-30 is manufactured by V. A. Degtyarev.

Many modern attack helicopters have a flexibly mounted 30 mm cannon. For example, the Boeing AH-64 has a ventral 30 mm M230LF, which (like all chain guns) is now the responsibility of Alliant Tech-systems (ATK) Ammunition Systems. The Eurocopter Tiger has a 30 mm Giat M 781 cannon in the same company's THL 30 chin turret. The Mil Mi-28 has a KBP-developed 30 mm Shipunov 2A42 cannon (produced for the BMP-2 armoured personnel carrier) in a chin turret, whereas the single-seat Kamov Ka-50 has the 2A42 mounted on the starboard fuselage side, moving only in elevation.

Some services prefer a 20 mm cannon. The Agusta Westland A129 and the Bell AH-1W SuperCobra have the three-barrel 20 mm GDATP M197 Gatling in a chin turret, firing at 1500 rd/min. The tandem-seat Ka-50-2 proposed to Turkey has a unique arrangement, with a 20 mm Giat M 621 mounted on an arm that is hinged on the lower port fuselage edge and is rotated below the aircraft for firing. This exceptionally low gun position appears to provide 360-degree cover, virtually irrespective of fuselage attitude. The same cannon is used in NC 621 podded form on various helicopters, and Giat offers it in the THL 20 turret. Giat is now developing the SH 20 pintle mount that enables the gun to be completely retracted into the cabin of the Super Puma and thus allows the door to be shut. The French company announced at the 2005 Paris Air Show that it was studying a similar concept for the NH 90. A Dene120 mm cannon is used on the company's Rooivalk attack helicopter, and is part of the Mi-24/35 Agile Super-Hind upgrade that has been developed by South Africa's Advanced Technologies and Engineering (ATE).

Returning to machine guns, GDATP markets the three-barrel 12.7 mm GAU19/A Gatling for external helicopter applications, firing at 1000/2000 rd/min. Belgium's FN Herstal still produces the 7.62 mm Mag and 12.7 mm M2HB-QCB Browning guns, and a variety of gun and rocket installations for helicopters. In January 2004, US Naval Air Systems Command awarded to FN Herstal an initial contract for the supply of 136 M3M 12.7 mm machine guns (designated GAU-21) to serve as pintle-mounted weapons on Navy and Marine Corps assault helicopters, replacing the same calibre M2 Browning. The M3M has a sustained fire rate of 200 rd/min, but is capable of up to 1100 rd/min, twice the maximum rate of the M2. The M3M will also provide over three times the barrel life of the M2. It will eventually equip the Boeing CH-46E, Sikorsky CH-53D/E and HH/SH-60, Bell UH-1 and Bell/Boeing MV-22.

Rockets

Rockets provide longer range and can deliver more effective warheads than automatic weapons. Their larger calibre allows the use of shaped charges, and (in recent years) flechette and cargo warheads. It also facilitates the introduction of laser guidance and control systems. The most widely employed rockets have calibres of 68 to 81 mm and may be effective to a range of around five kilometres.

The Western market is largely dominated by General Dynamic Armamanent and Technical Products' 70 mm Hydra-70 or APKWS (Advanced Precision Kill Weapon System). A typical round with Mk 66 Mod 4 motor weighs 6.2 kg and is effective against soft and lightly armoured targets. Europe's leaders in this field are FZ (Forges de Zeebrugge) and TDA Armements, both part of the Thales group. These companies produce 68 mm and 2.75-inch (70 mm) rockets. Other principals include Canada's Bristol Aerospace, part of Magellan Aerospace and manufacturer of the 70 mm CRV7, which is claimed to be the best rocket in its class in terms of standoff range, kinetic energy and accuracy.

Large-calibre rockets such as America's five-inch (127 mm) Hvar (High Velocity Aircraft Rocket) appear to have gone out of favour in the West, perhaps because of the availability of precision guided weapons, but Russia retains a wide range of rocket projectiles from 57 to 240 mm.

In 2003 General Dynamics was awarded a US Army contract to act as systems integrator for the Block 1 development of a laser-guided version of its Hydra70/APKWS, using BAE Systems seekers and guidance and control system. Russia is developing (or has already developed) the much heavier laser-guided 122 mm S-13L, which weighs 75 kg and carries a 31.8-kg warhead. The S-I 3L is planned for use on both rotary- and fixed-wing aircraft.

Air-to-Air

The use of air-to-air guided weapons on helicopters was pioneered by the Soviet Union, which in the early 1980s began fitting some Mi-24s with the 45 kg infrared-homing Molniya R-60 (AA-8). The R-60 series has been criticised on the grounds that its warhead is too small to be effective. Its maximum range is very limited: even the improved export R-60MK is credited with only ten kilometres in a head-on engagement.

In seeking an off-the-shelf counterpart, the US Army's response was to adapt a lightweight, shoulder-launched, surface-to-air missile; the Raytheon Fim-92 Stinger. This weighs only 10.1 kg (12.3 kg in launch tube), benefiting from the extreme accuracy provided by infrared homing, which allows for a lightweight warhead. Ground-launched Stingers are estimated to have over 270 kills to their credit, mostly in Afghanistan in the 1980s. Deliveries of the Air-To-Air Stinger (Atas) for the US Army Bell OH-58C/D began in 1988, with the Fim-92B Stinger-Post and Fim92C Stinger-RMP (Reprogrammable MicroProcessor). Atas now also equips the Army's MH-60 and is planned for the AH-64D and the Marine Corps AH-1Z.

The current Atas version is the Fim92D Stinger-RMP Block I, which introduced a two-colour seeker, a ring laser gyro to generate launch lead-angle, a lithium battery and increased processing power. The Stinger Air-To-Air Launcher (Atal) complete with two missiles weighs 49.3 kg, but Raytheon has now developed the Common Stinger Launcher (CSL), reducing this figure to 41.8 kg. Atas is already fielded on over 350 helicopters. More than 44,000 Stingers have been built and the missile will remain in the US Army inventory until at least 2018.

Western Europe's rival is the 18.7 kg MBDA Atam (Air-To-Air Mistral), which entered service on French Air Mobile Brigade Gazelles in 1998 and is cleared for use on the Tiger. It is claimed to be more manoeuvrable than the Stinger, to deliver a heavier (3.0 kg) warhead and to be usable throughout the helicopter's flight envelope. Two twin-round launchers represent a weight penalty of 200 kg. The Atam has also been selected for the South African Air Force Rooivalk.

The Thales Air Defence Air-To-Air Starstreak was proposed for the British Army's WAH-64, but firing trials from a US Army Apache in the late 1990s revealed problems with debris ingestion from the fragmenting nose-cap. This installation appears to have been abandoned.

Russia's own use of shoulder-launched Sams on helicopters has centred on the 10.5 kg KBM 9M39 Igla (SA-18), which has been adopted for the Mi-28 and Ka-50/52 and is being retrofitted to some older Russian types. In other cases anti-armour weapons have been adapted, notably the radio-guided 33.5 kg KBM 9Ml20 Ataka-V (AT-9) and the supersonic, laser beam-riding KBP 9M121 Vikhr (AT-16).

Anti-Armour

In the early postwar period all the major powers came to appreciate that a helicopter represented a very flexible means to respond to armoured threats, supplementing less-mobile ground-based systems. Germany had developed wire guidance for air-launched missiles in WWII, and this appeared to provide a jam-free solution to the problem of delivering a large warhead to the tank with the required accuracy.

Britain carried out some early trials with wire-guided test rounds and concluded that the concept was ruled out by frequent wire breakages. Attention therefore turned to more sophisticated (homing) missiles, the development of which proved to be beyond the current level of technology. Benefiting from the lack of competition, France's SS-10 became the world leader in wire-guided air-launched missiles. This and the improved SS-11 were both used in Algeria, and the latter saw limited service on US Army UH-1 s in Vietnam.

Seeking something better than the SS-11, America purchased the 21.4-kg Raytheon (originally Hughes) BGM-71 Tow, which entered service in 1965. Like the rail-launched SS-10/11 series, the Tow employs wire guidance, but it is launched from a tube, which also serves as a canister for storage and transportation. As for most first-generation anti-armour missiles, the Tow employs Saclos (semi-active command to line-of-sight) guidance, the gunner holding his sight on the target and an infrared seeker on the launch unit tracking a flare carried by the missile. The angular error is automatically measured and corrective signals are sent down the wire that is dispensed from the base of the Tow.

During the Vietnam War some 162 Tows were fired from US Army helicopters and 124 of these scored hits. However, in the Iran-Iraq conflict of the 1980s, it was found that the Tow could easily be decoyed by a hand-held flare, so a coded beacon was introduced on the missile. Over 660,000 examples of Tow have now been manufactured for service in more than 40 countries.

Later developments included the 22.6-kg, fly-over, top-attack Tow-2B with downward-firing explosively-formed penetrator (EFP) warheads, and the 23.0 kg Tow-2B Aero with a low-drag nose and a longer wire, increasing maximum range from 3.75 to 4.50 kilometres. This may well represent the practical limit for wire guidance, hence the current interest in the use of a stealthy one-way radio command link. Raytheon's Tow-2B RF has been demonstrated successfully but requires further development.

It may be that--in the light of recent operational experience--new anti-armour weapon developments have slipped down (if not off/the Pentagon's list of priorities. On the other hand, the US Army has already purchased more than 7000 Itas (Improved Target Acquisition Systems) for the Tow, and the Tow-2B with Itas has been selected as the US Marine Corps next-generation AAWS-H (Anti-Armor Weapon System--Heavy).

Europe's wire-guided, tube-launched rival to the Tow is the MBDA (formerly Euromissile) Hot series, the latest of which is the 24.5-kg Hot 3, with enhanced terminal effectiveness and anti-jamming peformance. The Hot 3 will serve on both the French and German versions of the Eurocopter Tiger, but Germany may later switch to the third-generation infrared-homing 50 kg Trigat-LR, for which EadsLFK now serves as prime contractor. The Trigat-LR is capable of five km (compared to 4.3 km for the Hot), but its range could be extended to seven km if required. Its acquisition has been long delayed, but Eads says that this will soon be rediscussed in Parliament.

The Soviets were quicker than the West to abandon wire guidance, although the earlier concept remains in widespread use in the form of the lightweight, rail-launched 12.0 to 13.5-kg KBM 9M14M Malyutka (AT-3), for which a variety of upgrades (especially relating to the warhead) remain available. Maximum range is three km.

Radio control (initially command and later saclos guidance) was used from the outset for the much heavier 29.0 kg Nudelman 9M17P Skorpion member of the Falanga (AT-2) series, which has a range of 2.5 metres. It has been used on Mi-8/17s and Mi-24Ds but is reportedly being retired. Three new alternative warheads are marketed by the Kovrov Mechanical Plant.

The success of radio guidance in the case of the Falanga may have encouraged development of the 31.8 kg, tube launched, similarly guided KBM 9Ml14 Kokon (AT-6), which was introduced as its replacement in 1978 and has a four km range. This was followed by a slightly supersonic derivative, the 33.5 kg KBM 9M120 Ataka-V (AT-9), which likewise employs the Shturm-V guidance system. The Ataka-V has a range of six km.

In both the East and West, experience with subsonic, saclos-guided anti-armour missiles led to requirements for supersonic weapons that could successfully exploit brief, long-range firing opportunities, and allowed the launch aircraft to drop below cover or engage another target immediately after firing.

The first such missile was the Lockheed Martin AGM-114 Hellfire II (originally a joint venture by Rockwell International and Martin Marietta), which cruises supersonically and has a range of over eight km. It employs laser-spot homing and can thus be used in a fire-and-forget mode against a target illuminated by a forward air controller with a coded laser designator. More than 18,000 Hellfires have been manufactured for the US services and 14 international customers. Over 1000 were launched during the 2003 invasion of Iraq.

The current laser-homing AGM-114K weighs 45 kg and has a Heat (high explosive, anti-tank) warhead. The AGM-114L Longbow Hellfire used on the Boeing AH-64D weighs 49 kg and employs millimetre-wave radar guidance, which provides all-weather capability. Also available is the laser-homing AGM-114M with a blast-fragmentation warhead, and the similarly guided AGM-114N with a thermobaric warhead. The latter was introduced on US Marine Corps AH-1Ws in 2003 for operations in Iraq.

The 50-kg MBDA Brimstone was developed to meet a British requirement for an anti-armour weapon to replace the BL755 cluster bomb on fast jet aircraft such as the BAE Systems Harrier. It was decided to produce a derivative of the helicopter-borne Hellfire that could be cleared for carriage and firing at much higher speeds and could autonomously attack off-track targets in all weather conditions. This led to the development of a small millimetre-wave radar and an automatic target recognition facility. The resulting Brimstone could, in principle, also be cleared for use from helicopters, but tactical philosophy has recently swung in favour of man-in-the-loop guidance to avoid friendly fire accidents.

Another long-range anti-armour missile is the laser-homing Denel Aerospace Mokopa, which is being produced for the Rooivalk helicopter and provides a firing range of ten km.

Russia's equivalent of the supersonic Hellfire is the tube-launched KBP 9M121 Vikhr (AT-16), which weighs 45 kg or 59 kg in its canister. It is a far more slender missile than the rail-launched Hellfire, with a length of approximately 2.45 metres and a 13 cm diameter, the corresponding figures for the Hellfire being 1.63/1.75 metres and 17.8 cm. The Vikhr employs laser beam-riding in order that the target can be engaged with two rounds simultaneously, and so that day/night strikes can be made on targets with low millimetric-wave contrast. Since most of the avionics cost is in the Shkval fire control system on the launch aircraft, the Vikhr represents a relatively low-cost approach; KBP's philosophy being that expensive homing missiles should be reserved for high-contrast targets. The Vikhr is an operationally flexible weapon, which can penetrate 900 to 1000 mm of armour, and up to 3.5 metres of reinforced concrete. It provides a maximum range of ten km. It entered service with Russian forces in 1996, and by 2001 was being employed in Chechnya on Russian Army Ka-50s, which can carry up to twelve in combination with the 30 mm 2A42 cannon and 80 S-8 80 mm unguided rockets.

Whatever the lessons learned by the Russian Army in Chechnya, the trend in Western thinking appears to be toward lock-on-after-launch, in order to make possible longer ranges and firing from behind cover, while retaining man-in-the-loop guidance to minimise the risk of friendly fire accidents.

One solution is to use a fibre-optic link feeding a video image back to the operator; a system that has successfully been demonstrated in experimental firings to a range of 60 km. Several companies are working in this field, but the current leader appears to be Rafael with the Spike-ER missile, formerly referred to as NTD. The Spike-ER can be locked on to the target either before or after launch, and (once locked on) can be left to strike autonomously or monitored by the operator. It weighs only 33 kg in its launch tube, has a maximum range of eight kilometres and normally employs a lofted on-top attack. A dual CCD/IIR seeker provides for day/night operation and the warhead can penetrate up to 1000 mm of rolled homogeneous armour. Rafael, Diehl and Rheinmetall have formed the Eurospike consortium to promote this and the ground-launched Spike-LR missile throughout Europe.

If the Spike-ER repeats the marketing success of the ground-based version, then Russia may not be so eager to adopt the KBP Hermes family of missiles, which is proposed to succeed the Vikhr and which retains well-established laser spot-homing. The air-launched Hermes-A combines inertial mid-course guidance and laser homing. Weighing less than 110 kg in its launch tube, it is designed to carry a 28-kg warhead over a maximum range of 18 km.

At time of writing the much lighter (49 kg) Lockheed Martin Joint Common Missile (JCM) is still under development to replace the Tow, Hellfire and Maverick on US Army and Marine Corps helicopters and the latter's fixed-wing aircraft. Whereas the Hermes is limited to laser spot-homing, the JCM will have a trimode seeker, combining semi-active laser, millimetre-wave and imaging-infrared. It is also to have a General Dynamics warhead and an Aerojet/ Roxel pulse-sustain motor, which will provide a range of 16 km from helicopters and up to 28 km from high-speed fixed-wing aircraft.

In late 2004 the Pentagon proposed to terminate the JCM on cost grounds, but there is no certainty that Congress will approve such action, and trials currently appear to be proceeding well. The finalisation of a road map for the entire spectrum of US land attack systems, due shortly, may well win a reprieve for what would clearly be a major technological advance in this class of weaponry.

Anti-Ship Missiles

The US Navy has led the world in many types of armament development, but has been slow to adopt helicopter-borne, anti-ship guided missiles. This is partly because that service has ample numbers of fixed-wing attack aircraft, but it is probably also due to the realisation that it takes a heavy warhead to sink a vessel of any great size.

Lightweight missiles nonetheless provide a helicopter with the possibility of disabling a number of small attack craft. A realistic minimum size may well be represented by the 103 kg MBDA AS.15TT and 145 kg Sea Skua. Russian naval helicopters optimistically employ the much lighter (33.5 kg) KBM Ataka-V.

An altogether more serious approach was taken in the Antipodean arming of Kaman SH-2Gs, Australia choosing the 350-kg Kongsberg AGM-119B Penguin, and New Zealand the 310-kg Raytheon AGM-65 Maverick. The 325-kg MBDA Marte Mk 2/S is to be used on the NH90 and EH-101. It is noteworthy that the turbojet-powered Kongsberg NSM will be even heavier, at 410 kg. The French side of MBDA is working with Kongsberg on the NSM, which suggests that it may also replace the rocket-powered 670 kg AM39 Exocet in French service.

Lightweight Torpedoes

Britain's present contribution to the field of helicopter-launched torpedoes is the Sting Ray, originally developed by Marconi Electronic Systems and now the responsibility of BAE Systems. The Sting Ray Mod 0 entered service with the Royal Navy and Royal Air Force in 1984 and was exported to Egypt, Norway and Thailand. In early 2003 BAE Systems was awarded a contract to upgrade British Sting Rays to Mod 1 standard, which will enter service in May 2006. An Insensitive Munition Warhead (IWM) is being developed and is scheduled to enter service in 2012. Britain plans to keep the Sting Ray in service until at least 2025.

American lightweight torpedo developments (formerly with Honeywell/ Alliant) are now centred on Raytheon Integrated Defense Systems. In October 2004 Raytheon was awarded a contract for full-rate production of the new Mk 54, to replace the Mk 46 and Mk 50. Referred to as the Lightweight Hybrid Torpedo (LHT), the Mk 54 might be regarded as a reduced-cost substitute for the Mk 50, retaining the latter's sonar system but reverting to the less expensive (though noisier) propulsion of the Mk 46.

In replacing the Mk 46 on its Seahawk and SeaSprite (in addition to its frigates and the AP-3C), Australia found the Eurotorp MU90/Impact to be the clear winner. In the 1980s France and Italy had been running two independent lightweight torpedo development programmes, with DCN and Thomson-Sintra working on the Murene, and Whitehead on the A.290. In 1990 the navies of France and Italy agreed upon a common requirement, and in 1993 Eurotorp was formed by DCN International (26 per cent), Thomson-CSF (now Thales) (24 per cent), and Whitehead Alenia Sistemi Subacquei (50).

The MU90/Impact is a 300 kg torpedo with a range of ten kilometres. It is in series production for the navies of Australia, Denmark, France, Germany, Italy and Poland. The Australian orders alone are worth 300 million [euro]. Deliveries of the MU90/Impact began in 2001, and over 1000 have now been ordered. A 'hardkill' version has also been developed. Eurotorp is additionally responsible for the older 244 kg A.244/s Mod 3, of which over 1000 have been manufactured for 15 navies. It has a range of 13.5 km.
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Title Annotation:Rotorcraft: armament
Author:Braybrook, Roy
Publication:Armada International
Geographic Code:1USA
Date:Oct 1, 2005
Words:3995
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