Earth-moving add-ons for choppers: scout, utility and transport helicopters can be transformed into effective ground attack systems by the addition of guns, bombs, grenade-launchers, mine-dispensers, rocket projectiles, guided missiles and appropriate sighting systems.

Earth-moving add-ons for choppers: scout, utility and transport helicopters can be transformed into effective ground attack systems by the addition of guns, bombs, grenade-launchers, mine-dispensers, rocket projectiles, guided missiles and appropriate sighting systems. For nations free from the threat of massed tank assaults, this approach represents an attractive alternative to the dedicated attack helicopter. The following discussion looks at some of the principal weapon options. (Airbone Warfare)

The most basic of aircraft armaments is the automatic weapon. Unless the intention is to kill unprotected personnel in the open, the 7.62 mm machine gun is of limited value. The 12.7 mm provides far more effective range and, with ammunition from companies such as Eurometaal, FN Herstal, Raufoss, Winchester and so forth, can destroy lightly-armoured vehicles and small boats. The German Army's anti-tank version of The Tiger will have a 12.7 mm gun as secondary armament.

Utility helicopter applications are exemplified by Belgium's FN Herstal HMP heavy machine gun pod, which houses an M3P (a re-engineered Browning M3) and 250 rounds. The HMP-RL pod adds an MRL 70 rocket launcher with four 70 mm projectiles, extending range from 1200 to 4000 metres. The trend away from rifle calibres is illustrated by the three-barrel 12.7 mm General Dynamics GAU19/A Gatling gun, which is used on US Air Force Special Operations helicopters and Turkey's UH-60s.

Russia employs a variety of gun pods, including the GUV or Type 9A669, normally housing three four-barrel Gatlings: two 7.62 mm Type 9A-662 guns with a total of 1800 rounds and a 12.7 mm Type 9A-624 with 750 rounds. The GUV can alternatively contain a 30 mm Type 9A-800 grenade launcher with 300 rounds. The UPK-23-250 accommodates the twin-barrel 23 mm GSh-23L with 250 rounds.

Some Russian pods allow the guns to be depressed for strafing. The SPPU22-01 from the MMPP design bureau houses a GSh-23L that can be lowered through 30 degrees. The Type 9A-4273 pod produced by Maz Dzerzhinets has a single-barrel 30 mm cannon (presumably a GSh-30K) that can be depressed through a similar angle.

France's Giat is another leader in helicopter weapons. The 20 mm 20M621 is used on a fixed 23A forward-firing external mount, in the NC621 gun pod, and as the floor-mounted MS621 for lateral cover. The THL20 turret with the 20M621 is used on Romania's IAR-330 Socat Puma. It seems likely that the THL30 developed for the Tiger on the basis of the 30M781 cannon will be applied to other types, just as Denel's 20 mm Vektor G12 turret, developed for the Rooivalk, has reportedly been applied to Algerian Mi-24s. The threebarrel 20 mm General Dynamics M197 Gatling gun is used in the Otobreda turret for the A 129 and, it is worthy of notice, the French Giat turret for the American RAH-66 Comanche.

Looking to the future, the Mauser 30 mm recoilless RMK30 cannon appears to be well suited to external helicopter applications.

Rocket Projectiles

Most current rocket projectiles suitable for helicopter use are of 70 to 80 mm calibre. For example, the Russians are replacing their long-established 57 mm S-5 series with the 80 mm S-8, carried in the five-round B-13 or 20-round B8V20A launcher.

The most important rocket globally is probably the 70 mm General Dynamics Hydra 70, an improved version of the old 2.75-inch Ffar (folding-fin aerial rocket). Use in the ground attack role from helicopters necessitated a modified rocket motor to take it quickly through the rotor downwash. The resulting Hydra 70 comes with a variety of unitary and cargo warheads (including two variants with 1180 four-gram flechettes). The US Army employs the lightweight seven-tube M260 and 19tube M261 launchers, the corresponding US Navy units being the reusable LAU-68D/A and LAU-61C/A.

For the future, the US Army plans to fill the gap between the Hydra 70 and the Hellfire guided missile (discussed later) with the Advanced Precision Kill Weapon System (APKWS) in the form of a Hydra 70 with a laser sensor and guidance package. The APKWS concept derives from Gulf War experience, in which many targets required a direct hit but did not justify the cost of Hellfire. This guided rocket will use the 4.54 kg M151 HE/fragmentation warhead and the M260/261 launchers. In August 2001, flight tests began with BAE Systems and Raytheon prototypes under the LCPK (low-cost precision kill) technology demonstration programme. Raytheon's design employs Paveway laser technology and is expected to cost less than $10,000 per unit. It will provide an effective range of up to six kilometres, and reduce circular error of probability down from the current 20 to 120 meters to one meter.

Canada's Bristol Aerospace CRV7 is claimed to be the leading 70 mm unguided rocket weapon, providing greater stand-off distance, higher kinetic energy and superior accuracy. The fast-burning C17 motor for helicopter use provides 33 per cent more total impulse than the Mk 66 of the Hydra series. Warhead options include the WDU-5002 Fat (Flechette Anti-Tank) with five 680-gram tungsten rods, the WDU-5001/B PHEI (Penetrator High Explosive Incendiary) for hardened aircraft shelters, and the Raufoss-developed Heisap (High Explosive Incendiary Semi-Armour Piercing) for anti-ship use.

Europe's leading rocket projectile manufacturer is TDA Armements, of which Forges de Zeebrugge (FZ) is a subsidiary. TDA products include Multidart flechette rockets in 68 mm (as selected for the French Army Tiger) and 100 mm. FZ began making the Ffar under US Navy licence in 1956, and subsequently developed an improved 70mm generation. Recent developments include the FZ100 cargo war head dispensing nine shaped charges, and the FZ122 and Multidart 70 flechette warheads. TDA has been working on the development of a semi-active laser-guided version of the 68 mm Sneb rocket under the designation Syrocot (SYsteme de ROquettes a COrrection de Trajectoire).

The Italian company Snia-BPD earlier developed the 81 mm Snora in collaboration with Oerlikon, then independently developed the Medusa derivative, which has a modified tail and nose, a larger warhead and a maximum range of twelve kilometres (increased from ten). The 81 mm Medusa has been selected for the Italian Army's A 129.

Guided Missiles

In the beginning there was command guidance, the effectiveness of which depends heavily on the skill of the operator. This system has therefore generally been abandoned, although the radioguided Nudelman 9M17 Phalanga (AT2) and the wire-guided KBM 9M14 Malyutka (AT-3) remain in several inventories. The Kovrov Mechanical Plant offers three warhead upgrades for the Phalanga: an improved hollow charge, a blast device and an anti-personnel HE/fragmentation warhead.

Malyutka upgrades are marketed by KBM (teamed with Lomo) and the Czech VTUVM company. The KBM Malyutka-2 provides more powerful motors, the choice of an improved shaped charge or a blast warhead and semi-automatic command to line-of-sight (saclos) guidance, which reduces the skill-level required. The Lomo control module discriminates against decoy flares by detecting the roll of the two flares mounted on the missile base. The Malyutka-2T is a joint effort by Euromissile and Romania's Arsenalul Armatei, substituting the tandem warhead from the former's Milan-2T.

Saclos has been widely adopted, in the West with wire guidance to minimise countermeasures. The Raytheon BGM-71 Tow is probably the most widely used weapon in this class, over 660,000 rounds having been produced for 44 nations. The BGM-71E Tow 2A employs direct attack with a tandem warhead, and the BGM-71F Tow 2B is an overhead attack missile with two EFP (explosively-formed penetrator) warheads. The `US Army has recently developed a 2.85-kg `bunker-buster' blast warhead for the Tow 2A.

More than 85,000 Euromissile Hot rounds have been built for 19 nations. The tandem charge Hot 3 is the latest version, which entered service at the end of 1998. The correct stand-off distance is measured by a laser in the nose, since a conventional probe cannot be accommodated in the launch tube. On initiation, the prercursor charge is ejected forwards to explode the target's ERA (explosive reactive armour), detonation of the main charge being timedelayed.

The use of wires restricts missile range to around 4000 metres and speed to perhaps 200 m/sec (Mach 0.6). Radiobased saclos is used by KBM's 9M114 Shturm-V (AT-6) and its 9M120 AtakaV (AT-9) derivative. The Shturm, which was used in Afghanistan, is claimed to have been the first supersonic anti-tank guided missile, and the average flight speed for Ataka-V is given as 350 to 400 m/sec. The Shturm is marketed with the choice of a shaped charge, blast-fragmentation, rod-type penetrator or fuel-air explosive warhead, while the Ataka reportedly introduced tandem charges. The Ataka is claimed to be less susceptible to countermeasures than KBP's Vikhr (discussed below).

America's first supersonic anti-tank missile was the laser-spot homing AGM-114, now produced by Hellfire Systems, a joint venture by Boeing and Lockheed Martin. The current variants are the AGM-114F, which introduced a tandem charge, and the AGM-114K Hellfire II, which was designed for a high EO countermeasures environment. It also has a longer range, an improved warhead, a digital autopilot and the ability to fly below low cloud. The AGM-114M is being developed with a new 12.5 kg blast-fragmentation warhead for anti-ship use.

The Hellfire offers a nominal range of eight kilometres, and thus has few rivals. One possibility is the Denel/Kentron Mokopa, which will also (in baseline form) employ semi-active laser homing and a tandem warhead. The Mokopa is currently being developed for the Rooivalk.

Laser beam-riding is employed by the lighter Denel/Kentron Ingwe, which is now in production for the Rooivalk. This form of guidance is also used by KBP's 9M120 Vikhr (AT-16), which - like the Mokopa - has the outstanding maximum range of ten kilometres. The Vikhr, which was designed as a replacement for KBM's Ataka, is normally carried in the six-tube UPP-800 launcher, and is available with a shaped charge or proximity-fuzed fragmentation warhead (the latter for aircraft targets). Average speed to 8000 metres is 350 m/sec. There are reports of a next-generation Vikhr-M being developed, with a range of up to 15 km.

US Army demands for a fire-and-forget anti-tank missile led to development of the AGM-114L Longbow Hellfire for the AH-64D. It is guided by active millimetre-wave (mm-wave) radar and is produced by the Longbow Limited Liability Company, a joint venture by Lockheed Martin and Northrop Grumman. Under a five-year contract, 10,397 missiles are to be delivered by August 2005.

One fire-and-forget alternative to mm-wave guidance is imaging infrared (IIR), although the latter has to be locked on to the target before launch. It is used by the Raytheon Tow-F&F, the "w" in Tow here meaning wire-less, rather than wire-guided. The Tow-F&F is a derivative of the top-attack Tow 2B with the IIR seeker from the AIM-9X and increased range. Radio-based saclos guidance is retained as a reversionary mode. The main development contract was awarded to Raytheon last year and the Tow-F&F is expected to enter production in 2003.

Another application for IIR guidance is the Trigat-LR, which is being jointly developed by Eads and MBDA, and is expected to supersede the Hot 3 on the German Army Tiger. It is argued that, by retaining lock-on before launch, the Trigat-LR avoids the potential friendly fire accidents associated with exploiting the target-recognition possibilities of mm-wave guidance.

Another way to keep an operator "in the loop" is to use fibre-optic guidance, as is being developed with the Eads Polyphem vehicle. However, fibre-optic guidance with day/night sensors is already employed by the Rafael N-TD, a long-range development of the lightweight Spike missile. The N-TD is being promoted in Germany as an alternative to the Trigat-LR.

In short

* "Heavy automatic weapons remain an important element in helicopter armament"

* "Laser-guided 68 to 81 mm rocket projectiles will deal cost-effectively with targets that do not warrant the expenditure of an antitank guided missile"

* "Wire guidance limits missile speed and range"

* "Supersonic missiles provide advantages against fleeting targets and those with active defence systems"

* "Fire-and-forget missiles reduce helicopter exposure, but may increase friendly fire accidents."