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Swiss knives for jack-of-all-trades whirlybirds.

In times of defence economies, "multirole" is key. No military equipment warrants that appellation better than the armed utility helicopter, serving as troop transport, cargolifter, gunship, escort, and combat search-and-rescue platform. All vtol (vertical take-off and landing) aircraft are weight-sensitive, hence the emphasis in choice of weaponry is on lightness. Utility helicopters will become even more potent with the new generation of laserhoming rocket projectiles and the miniature air-surface guided missiles being developed for drone applications.

IN THE ALGERIAN War of 1954-62 the French Air Force developed a flexible mounting for a 20 mm cannon on its Sikorsky H-34s (S-58s). The French Army installed light machine guns and rocket pods on some Vertol H-21s ('La Banane ) and on the turbine-engined Sud- Est Alouette II, some examples of which were armed with Nord SS.10/11 guided missiles.

Helicopter armament advanced further with American operations in Vietnam (1962-75). Initially, US helicopters were used to transport Vietnamese troops and relied for fire support at the LZ (landing zone) on ARVN (Army of the Republic of Vietnam) mortars and artillery and VNAF (Vietnam Air Force) air strikes. This support proved so ineffective that helicopter crewmen began carrying rifles or the 0.45- calibre M3 lGrease Gun, and mounting light machine guns to give lateral cover.

The concept of arming utility helicopters advanced further with the arrival of the Bell Huey series in late 1962. The UH-1B/C was given forward- firing seven/eight-tube 2.75- inch rocket pods and 7.62-mm M37C or M60C machine guns, all mounted on the skids. Some 6700 rounds of ammunition were carried in twelve boxes, and fed electrically to the guns via metal chutes.

In many cases an M60B was simply hung by elastic cord from the top of either doorframe. Gunners then found that the best way to achieve area coverage was to try to hold the aim fixed.

Subsequently, the four M60s were replaced by two flexibly-mounted, forward- firing six-barrel 7.62-mm General Electric Ml34 Miniguns, each firing at 2000 rd/min. The 'Heavy Hog' version of UH-1C also had a Ford Aerospace M75 40-mm grenade launcher in a chin turret. The Nord SS.l 1 anti-armour guided missile was introduced in Vietnam in 1965, and the Hughes/Raytheon BGM-71 Tow in 1972.

* POST 'NAM

In 1976 the US Army selected the tentonne Sikorsky UH-60 Black Hawk to replace the 4.4-tonne 'Huey'. The UH-60A entered service in 1979 and led to various armed models, including the MH-60L with Ml34 door guns and stub wings that can mount 30-mm Alliant Techsystems M230 Chain Guns. Armed export versions include the AH-60L Arpia III for Colombia.

Just as the Vietnam War spurred the development of armed Hueys, Soviet operations in Afghanistan (1979-89) accelerated weaponisation of the Mil Mi-8 series, producing what are probably the worlds most heavily armed helicopters, the 13-tonne Ulan-Ude Mi-171Sh and the Kazan Mi-17- IV.

For example, the Mi-17-1V can carry 80 S- 8 80-mm or 192 S-5 57-mm rockets, or four twin-barrel 23-mm UPK-23-250 gunpods. It has provisions for a remotely-controlled PKT/PKTM 7.62-mm machine gun in the nose and at the rear, and troops can fire their AKM assault rifles or PK/RPK machine guns on six swivel mounts in the side windows.

* MACHINE GUNS

Automatic Weapons combine the advantages of relatively low cost, broadaspect coverage and fire persistence.

Lightweight single-barrel guns are exemplified by the 7.62 mm FN Herstal MAG 58M, which has the US Army designation M240D. The same company's standard heavy machine gun is the 12.7-mm FN M3M/M3P/GAU-21 series.

The pintle-mounted M3M is fitted with a 300 or 600-round ammunition box, and fires at 1025 rd/min. Applications include the US Air Force Sikorsky HH/MH-60G. Recent platform integrations for the M3P include the FN Herstal HMP400 and the RMP pods (the latter with three 70 mm rockets) on the AgustaWestland AW 101. The M3P has also been selected for the US Armvs Bell OH-58D.

The use of multiple barrels, following the lead of the pioneering Gast and Catling guns, overcomes the cyclic-rate limitation of a single-chamber weapon. One of the best examples for helicopter applications is the General Dynamics Armament & Technical Products (GDATP) three-barrel 12.7-mm GAU-19/A, which is externally- powered and fires at 1000/2000 rd/min. Applications include some US Air Force HH/MH-60Gs, Colombian Air Force Bell UH-ls and Mexican Navy MDH MD-902s and Mil Mi-17s.

The Soviets developed two four-barrel guns, both self-powered (ie, gas-operated). The lighter design is the Shipunov GShG- 7.62, which fires at 6000 rd/min. It is used in gunpods and in the nose turret of the Kamov Ka-29. The other is 12.7 mm Yakushev-Borsov (Yak-B) or 9A624, which was the original chin turret armament for the Mil Mi-24.

In Vietnam the US Army demanded extremely high cyclic rates for suppressive fire. This led to the electrically-powered six- barrel General Electric 7.62 mm GAU-2B/A Gatling gun or Ml34, which was capable of 6000 rd/min, but was generally operated at 4000/2000 rd/min. It has been employed in fixed, pintle-mounted and turreted forms on a wide range of rotary-wing aircraft, but its reliability is problematic.

Arizona-based Dillon Aero has reengineered the Ml34, and restricted cyclic rate to 3000 rd/min, giving outstanding reliability and reduced recoil loads. The new gun is known to the US Army as the M134D and to the US Navy as the G AU-17/A.

Dillon Aero has now standardised on the M134D-H Titanium Hybrid version, which is 5.0 kg lighter than the M134D (Steel). It uses some titanium components from the M134D-T Titanium for lightness and corrosion-resistance, but retains the steel housing of the original M134D for longer (million-round) life.

The company has now produced over 2200 new-build M134Ds and more than 3250 upgrade kits for old GE-built Ml34s. Foreign applications include Jordanian Socom helicopters.

The demand for improved Ml34s has encouraged another Arizona-based company, Garwood Industries, to enter the market with its M134G. Firing rate is selectable as 3000/3200/4000 rd/min. The Ml 34G employs chrome-lined barrels with phosphate coatings, manufactured by FNH USA. Both Dillon Aero and Garwood quote a barrel life of 200,000 rounds.

* CANNON

In helicopter applications, cannon are generally not required to produce the high firing rates used in fighter aircraft. In any event, the carriage of large numbers of shells is unacceptable from a weight viewpoint.

Nexter Systems produces the 20 mm single-barrel 20M621 in various forms. As the NC621 pod, it has been applied to several Eurocopter products, recently including the EC635. The pintle-mounted SH20, firing at 750 rd/min, is employed in a retractable installation on the Eurocopter EC725. The THL20 turret has been ordered for the HAL Light Combat Helicopter. Nexter s 30 mm 30M781 cannon is used in the THL30 turret of the Eurocopter Tiger.

In the 'SuperHind' Mi-24 upgrade developed for the Algerian Air Force by South Africa's Advanced Technologies & Engineering (ATE), the four-barrel 12.7-mm gun in the chin turret is replaced by a 20-mm single-barrel Denel Land Systems GI-2.

The heaviest Russian single-barrel cannon in this class is the 30-mm Shipunov 2A42 from the BMP-2 ground vehicle, but this has been applied only to the Mil Mi-28 and Kamov Ka-50 attack helicopters. Likewise the Alliant Techsystems (ATK) 30- mm externally-powered M230 Chain Gun is used only on the Boeing AH-64 series.

In developing the Mi-24 to meet operational demands in Afghanistan, Mil first replaced the 12.7-mm four-barrel turret gun with a twin-barrel 23 mm GSh 23L cannon. This concept was dropped, but the GSh-231, is used in UPK 23-250 pods on various utility helicopters, including the Mi- 171 Sh, Mi-17-1V and PZL-Swidnik W-3PL Gruszec. In place of the chin turret, the Mi- 24P has a fixed twin -barrel 30-mm GSh-30K on the starboard fuselage side.

GDATPs 20 mm three-barrel Ml97 cannon is a lightweight derivative of the six- barrel M61A1 Vulcan used in fixed-wing aircraft, and can fire at up to 1500 rd/min. It is used as a turreted gun in attack helicopters, and in the GPU-2/A gunpod, which holds 300 rounds.

* ROCKETS

The majority of unguided rocket projectiles sed on Western helicopters are the hales/TDA Armements 68 mm SNEB, the.75-inch/70 mm General Dynamics Hydra-70 or the Magellan/Bristol Aerospace CRV7.

Russian helicopters are generally armed with the 57 mm S-5 rocket, but this is being superseded by the 80 mm S-8. Chinese helicopters are seen with 57- and 68-mm rockets, presumably copied from the Russian and French originals, and also with the home-grown 90-mm Norinco Type 1 in seven-tube launchers and the 130 mm Type 82 in four-tube pods.

* ROCKETS TURNED MISSILES

The many unguided rockets held in storage offer a low-cost means to produce guided missiles, when combined with a laser homing kit. In comparison with a laserguided Raytheon AGM-65L/E2 Maverick or Lockheed Martin AGM-114 Hellfire, a Hydra-70 rocket has a small warhead, but this is an advantage when the target is soft and low collateral effects are required.

The need for a lightweight precision weapon (effectively a cheap complement for Hellfire) was recognised in the US Army study that followed Desert Storm of 1991. In 1996 the Department of the Army approved a Mission Need Statement (MNS) for the Apkws (Advanced Precision Kill Weapon System), specifically for helicopters. However, it was only in 2000 that the Operational Requirement Document (ORD) was formally approved.

The Apkws was envisioned as a laser- guided rocket (LGR) with a unit cost of less than S 10,000, an accuracy of around one metre, and a standoff range of at least six kilometres. It was to combine the GDATP Hydra-70 rocket motor, warhead and fuze with a small, strapdown solid-state laser seeker, an off-the-shelf inert ial measuring unit and a low-cost control system. The Apkws was expected to reduce cost-per-kill significantly, and increase the number of kills that one helicopter could achieve by a factor of up to 20.

The US Army selected BAH Systems asprime contractor for the Apkws in 2006, but zeroed funding in FY2008. In November 2008 the programme was taken over by the US Navy, to provide an accurate lightweight weapon for US Marine Corps helicopters.

The BAE Systems Apkws employs a Dasals (Distributed Aperture Semi-Active Laser Seeker) arrangement, with four sensors mounted in the leading edges of the canard surfaces. The mid-body guidance and control section allows the use of existing warheads, fuzes and rocket motors, and protects the sensors (on canards folded back in the launch tube) from the blast of preceding rockets.

The Apkws has been cleared for use on the US Marine Corps Bell UH-1Y and AH- 1W, and will later be cleared for the services AH- 1Z and the US Navy MH-60R (and Northrop Grumman MQ- 8C drone). The first batch of missiles for operational use in Afghanistan has now been delivered. The US Air Force is interested in acquiring Apkws for fixed-wing tactical aircraft.

In August 2009 the US Army issued a request for information on lightweight (less than 22.7 kg) precision strike weapons under the Ampm (Aviation Multi-Platform Munition) programme. This effort is primarily intended to allow the Bell OH-58D to combine long endurance with a large number of kills against thin-skinned vehicles and combatants in the open, when taking off under hot/high conditions in Iraq and Afghanistan. The US Army trialled three types of LG R in 2009, but appears to be waiting to see how the US Marine Corps Apkws performs operationally before placing orders.

One LGR tested by the US Army was the 70 mm Talon jointly developed by Raytheon and the Abu Dhabi-based Emirates Advanced Investments (EAI), presumably on the basis of the Raytheon LGR tested in 2006 under the Apkws programme. The Talon has since been successfully launched at ranges up to 6.0 km, and is claimed to be the only LGR to have achieved an air-launched direct hit from as short a range as 1.2 km.

If the United Arab Emirates place a launch order for the Talon to arm the AH-64D, the initial conversion kits ill be manufactured by Raytheon at Tucson, Arizona. The ability to manufacture the guidance and control section will then be transferred to EAI, but the laser seeker will remain a Raytheon product.

Another Ampm candidate is the Lockheed Martin Dagr (Direct Attack Guided Rocket), which uses seeker and guidance technology from its Hellfire and later air-ground missile projects. The modification kit is intended for both the Hvdra-70 and CRV7.

The Dagr has a launch weight of 15.9 kg with a 4.5 kg warhead, and 19 kg with a 7.7 kg warhead. It has a range of 7.0 km at sea level, and up to 12.0 km from 20,000 ft. It can engage targets moving at up to 90 km/hr. Lockheed Martin has designed two- and four-tube launchers for Dagr.

There have been at least 20 Dagr firings, including airborne launches from the AH- 64 D, OH-58D and AH-6. The Dagr is in limited production under US Air Force contract, reportedly to arm Iraqi Air Force Mil-17Is and ATK AC-208Bs, and Iraqi Army Air Corps Mil Mi-17s.

The third LGR tested by the US Army was the AT K/El bit Systems Gatr-L (Guided Advanced Technology Rocket -Laser). This combines an improved rocket motor by ATK and guidance and control technology from Elbit's Star (Smart Tactical Airborne Rocket), which is based on the laser seeker from its Lizard LGB.

The Gatr-L has also been tested on the Sikorsky/FJbit Armed Black Hawk (ABH) and is seen as a likely candidate for Israels AH-64s and AH -Is. It is proposed as a new-build weapon (rather than a modification kit) that provides improved kinematic performance, with a range of over eight kilometres.

Several European companies have produced test LGRs, but evidently lack the funding or motivation to complete development.

One that appears likely to go ahead is the Roketsan Cirit (Javelin), a completely new 70 mm LGR, designed in response to a Turkish Army requirement for a weapon for its Atak helicopter. It weighs 14 kg, and delivers a tri-mode (anti-armour, antipersonnel and incendiary) warhead over a range of eight kilometres. Development of Cirit is almost complete, and series production is expected to start shortly.

It appears that the emphasis in Russian LGRs is currently on heavy rockets, such as the 122-mm S-13L and 340-mm S-25L, which are used only on attack helicopters and fixed-wing aircraft.

* MISSILES

Despite early use of the SS. 10/11 and Tow, the idea of arming utility helicopters with guided missiles failed to take off in the West, due to the development of two-seat dedicated attack helicopters.

Maritime operations represent an exception to this rule, a wide range of antiship weapons being employed on what are basically naval utility helicopters. For example, the 310-kg MBDA Marte Mk 2/S is being cleared for use on the Italian Navy NH1 NH90 and AgustaWestland AW101, and the 385-kg Kongsberg Penguin AGM-119B is used' on the US Navy Sikorsky SH-60 Seahawk.

The 5.5-tonne Hindustan Aeronautics Dhruv (Sanskrit for 'Polaris') is flown by nine military operators. It is shown here armed with two twelve-tube 70-mm FZ rocket launchers and four MBDA Mistral air-air missiles. (Hindustan Aeronautics).

In the Soviet Union, where attack helicopters were developed only later, various guided missiles have been applied to the Mi-8 family, For example, today's Mi- 171 Sh (the export version of the Mi- 8AMTSh) can carry eight KBM-designed (Degtyarev-manufactured) 9M120 Ataka (AT-9) anti-armour guided weapons.

Returning to the US Army's Ampm programme, aside from the three LGRs, tests were carried out on the Raytheon Griffin and Textron Defense Systems Sharpshooter missiles. Little has been published regarding Sharpshooter, but the laser-homing, 15-kg Griffin offers off-boresight engagements, three fuzing options and GPS-reversion.

Griffin-A is ejected aft from the loading ramp of a US Marine Corps KC-130J Harvest Hawk. Griffin-B was designed to be ejected forwards from a launch tube under a drone. Griffin technology is also used in the 5.9-kg Raytheon STM (Small Tactical Munition) glide weapon.

The trend to arming drones has encouraged the development of several munitions in the 13-kg category, including the IAI Lahat (which has been tested on the Mi-8/17), the Lockheed Martin Scorpion, the MBDA Saber, and the laser beam-riding Thales UK LMM (Lightweight Multi-role Missile), which has been ordered for the Royal Navy's AgustaWestland AW 159 Lynx Wildcat.
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Title Annotation:Utility Helicopter Armament
Author:Braybrook, Roy
Publication:Armada International
Date:Jun 1, 2012
Words:2751
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