Weaponised Dhruv ALH, LCH & LOH

Hindustan Aeronautics Ltd (HAL), which has been associated with the tedious and long-drawn process of designing, developing and series-producing the ‘Dhruv’ advanced light helicopter (seven of which have been ordered by Ecuador’s Army), believes that the ‘Dhruv’ 5-tonne multi-role light medium twin-engined design does not represent a zero-sum game, that it is possible to wrap a slim, tandem-seat fuselage around the existing powerplant, transmission and rotor systems of this proven helicopter and derive two distinct derivatives: a light combat helicopter (LCH) optimised for high-altitude warfare; and an armed aeroscout capable of operating in the plains (for operating in tandem with fast-moving mechanised and armoured formations) and over jungle terrain in support of special operations forces and also taking part in combat search-and-rescue operations. Yet, as of now, only the IAF has committed to placing limited firm orders for the LCH, while Army HQ has refused to even examine the LCH’s obvious potential as an armed light observation helicopter (LOH), preferring instead to separately procure single-engined LOHs of an altogether new design of foreign origin. As things now stand, both the IAF and the Army have projected a requirement for 187 LOHs of which the majority will go to the Army. All these will be delivered during the 11th (2007-2012) and 12th (2012-2017) Defence Plans.

The LCH programme took off in early 2003 when the IAF ‘verbally’ pledged Rs3 billion to HAL for designing and developing the helicopter over a 24-month period. The 5.5-tonne, twin-engined LCH at that time was conceptualised as being optimised for all-weather observation and counter-insurgency operations at high altitudes. It will also be armed and equipped with weapons and nose-mounted mission sensors to intercept unmanned aerial vehicles, escort heliborne special operations forces, provide offensive firepower for ground operations urban terrain/built-up areas and for combat search-and-rescue operations, and undertake anti-armour operations. The airframe was to feature a narrow fuselage housing a pilot and a gunner/co-pilot in tandem configuration. The glass cockpit and windshield was required to have armour protection against 12.7mm armour-piercing rounds. Optronic sensors, including a FLIR/thermal imager and laser rangefinder/designator, were to be installed inside a nose-mounted gimballed payload assembly developed by the DRDO’s Dehra Dun-based IRDE facility. The electronic warfare suite was to include a DRDO-developed radar warning receiver, plus chaff/flare dispensers and a missile approach warning system. Things began to move in October 2006 when the MoD released initial R & D funds to HAL and authorised the IAF’s projected procurement request for 65 LCHs. As per present plans, HAL is due to roll out the first of three LCH prototypes early next year, with initial operational clearance being granted by March 2010, and full certification of airworthiness being granted by January 2011, 25 months after the LCH’s first flight.

Though the LCH is derived from the ‘Dhruv’ and will carry the same weapons package now being qualified on board the armed ‘Dhruv’ (that have been ordered by the Army for its projected Combat Aviation Brigade), the IAF has specified a top speed 25kph higher to allow it to run down and kill snooping UAVs if necessary. To make the LCH a survivable platform, HAL is following NATO’s MIL-STD-1290 crashworthiness standard, is designing its own impact absorbing landing gear and will improve on the Dhruv’s ballistic tolerance with up to 100kg of composite-/ceramics-based modular armour, whose positioning is based on an IAF study of the areas most likely to suffer bullet damage. The tandem-seat cockpits will each have twin side-by-side AMLCDs, will be NVG-compatible, will provide NBC protection to the crew, and will have a helmet-mounted targeting system co-developed by HAL and Israel’s Elbit Systems. The LCH will be capable of operating at heights of up to 6,000 metres or 18,000 feet, and will be powered by twin Ardiden 1H (1,200shp TM333-2C2 Shakti) engines co-developed by HAL and Turbomecca. The main and tail rotor blades will be of all-composite construction, with the main rotor blade tips featuring BERP-style sections for increased cruise speed.

The LCH’s armaments suite will comprise a THL-20 chin-mounted turret containing a 20mm Nexter Systems-built M-621 gun firing at a rate of 800 rounds per minute, stub-wing-mounted Forges de Zeebrugge-built LAU-FZ-231 launchers carrying 2.75-inch rockets, MBDA-built Mistral ATAM air-to-air missiles, or the DRDO-developed Nag anti-armour guided-missiles, which will have a maximum engagement range of 6km and will use a nose-mounted millimeter-wave radar for target acquisition-sum-homing. The LCH’s four-axis auto-hover and digital automatic flight control system have been developed in-house, while the Bangalore-based DARE is developing along with EADS the defensive aids suite. DARE has also developed in-house the digital mission computer and pylon interface boxes. The flight control actuator system has been co-developed by HAL and the UK-based APPH.

For the LOH requirements of the Army and IAF, HAL recently proposed a lighter LCH-derived platform powered by a single TM333-2C2 Shakti engine. The LOH will feature a roof-mounted stabilised optronic turret housing an integrated long-range observation system comprising a thermal imager, laser rangefinder and daylight TV.—Prasun K. Sengupta