CONNAN
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COMPLETE HISTORY OF DHRUV AND ITS DEVELOPMENT
The indigenously developed Dhruv is a multi-role new generation helicopter in the 5.5-ton weight class. Dhruv has multiple meanings and origins. "Dhruv" is a Sanskrit word that means "non-movable" or "immobile", or Firm or Constant. However, this word is most commonly used to refer "pole star". The Hindu version of Dhruv means Dhruv was a Prince and blessed by God, that the pole star will be named Dhruv and the whole universe would revolve around the star and be stationary and shine the brightest. When Dhruv prayed Lord Vishnu, Lord Vishnu gave him blessing and told him - "I will make a place for you in the sky from where nobody can remove you". And then he made Dhruv the 'pole star'.
HAL Dhruv is said to share many design features that are derivative of the Kawasaki BK-117 and EC-145, which is a variant of the BK-117. HAL started development of a new 12-seat helicopter known as the ALH (Advanced Light Helicopter) in July 1984. It was designed with assistance from MBB in Germany. It followed a similar layout to that of the BK-117 although it is a larger aircraft. The Dhruv might look a bit like a BK 117 but it is quite a lot larger and has a 4 bladed not 2 bladed tail rotor.
The Dhruv Advanced Light Helicopter has flown extensively in diverse terrains ranging from hot tropical deserts to the great Himalayan ranges. Dhruv has high military capabilities for heliborne assault, logistic support, casualty evacuation, reconnaissance and training. It can also be used as air observation post. It is designed to meet the requirement of both military and civil operations. The civil variant of Dhruv carries forward the ruggedness of the military variant. It can carry six passengers in the executive version and twelve in the passenger version.
The "Dhruv" Advanced Light Helicopter (ALH) designed and developed by Hindustan Aeronautics Limited (HAL), is a unique multirole, state-of- the-art, cost-effective helicopter in the 4-5 ton class. ALH has incorporated hingeless composite main rooter with elastomeric bearings, a bearingless composite tail rotor, integrated dynamic transmission system, full authority digitial engine control and crashworthy composite airframe.
The Advanced Light Helicopter is HALs flagship program and it has been accorded high priority in the country in terms of development, production and marketing for the next decade. Indigenously designed and developed to meet the requirements of the Army, Navy, Air Force and the Coast Guard, the ALH can fly at high altitudes, possesses sea-level high lift capability and performs at high speed. It is an armed gunship, a utility transport, an anti-submarine warfare/anti-surface vessel warfare helicopter and a platform for search and rescue and casualty evacuation. The ALHs are powered by two Turbomeca TM 333 turboshaft engines procured from France and these will be produced under licence by HAL.
With its wide body, specious and quite cabin, sliding doors, emergency exits, smooth and vibration free rides which are important for passenger comfort, the ALH fits well into the civil role. Large rear clamshell doors provide easy loading of stretchers or other bulky loads. The helicopter is planned for a wide range of civil roles like VIP travel, Commuter, Search and rescue, Emergency medical service, Underslung load, Disaster relief, Offshore operation etc. It is easy to fly and economical to maintain with all these operational flexibility.
ALH has been designed with close interaction with the military from the beginning. With sonar/sonics, radar, ESM, torpedoes, depth charges and anti Ship Missiles, ALH forms one of the most agile and quick response ASW, ASV platform in the world. With the turret gun, rockets, air-to-air missiles and third generation anti-tank missiles, ALH has the teeth for attack along with significant self defence and protection system.
The hingeless main rotor offers good maneuverability and maintenance-free operation. The advanced blade profiles ensure low noise, highspeed and efficient lift. The advanced cockpit reduces pilot workload. The extensive use of composites ensures longer life and low life cycle cost. High reliability is due to redundancy in critical system. Easy maintenance is due to modular design and BITE facility in major systems. Integrated Dynamic System offers low vulnerability, increased safety and reliability.
The ALH is built to international design standards stipulated by FAR and US MIL. Designed to cater to the diverse needs of Army, Navy and Air Force, as well as Civil sector, ALH has versatility to carry out a variety of roles. It can operate with equal ease over sea, high altitude, sandy deserts and adverse environmental conditions. The ALH entered the advanced stage of certification, having undergone extensive flight tests for demonstrating compliance with variety of requirements. A civil variant ALH prototype is also under development.
HAL concentrated on integration work. With the turret gun, rockets, air-to-air missiles and third generation anti-tank missiles, ALH has the teeth for attack together with self-defence and protection systems. The naval version of the ALH is fitted with sonar/sonics system, surveillance radar, ESM system and tactical mission system and is armed with torpedo/depth charges and anti-ship missiles for anti-submarine and anti-surface vessel missions.
The Dhruv features a 'System Bolkow' four-blade hingeless main rotor with carbon fibre composite blades. The blades have advanced aero foils, swept back tips for reduced nose, and feature a ballistic tolerance against bullet hits of up to 12.7mm calibre. The fibre elastoner rotor head holds the blade between a pair of CFRP star-plates, with manual blade folding and a rotor brake provided as standard equipment. A four blade bearing-less crossbeam tail rotor is fitted on the starboard side of the pylon. Vibration damping is provided by an anti-resonance isolation system compromising four isolator elements between the fuselage and the main gearbox. An integrated drive system transmission comprises of the rotor hub, main transmission, upper controls and main rotor hydraulics. The Dhruv also features a four axis automatic flight control system, with an integrated control & stability augmentation system from France.
The airframe makes extensive use of composites (Glass Fibre, Carbon and Kevlar) and accounts for 29% of overall structural weight and 60% of surface area. The military variants include crashworthy fuel tanks, frangible couplings and infra-red suppressors for the engines. The helicopter design enables the crew to survive vertical impacts of up to 30 feet per second, due to the safety seats and a design of controlled deformation of fuselage crumple zones. The cabin was designed to seat 12 people, however 14 can be accommodated in a high-density configuration. Rearward-sliding passenger doors are featured on either end, with large clamshell doors at the rear of the cabin. The clamshell doors can be removed, in exceptional cases, to carry unusual & unwieldy loads. An underslung load hook is standard on military variants. The air ambulance variant enables the Dhruv to accommodate two to four stretchers, with a couple of attendants.
A communication radio (U/UHF, HF/SSB and standby UHF modes), IFF & intercom, with a Doppler navigation system, TAS system, radio altimeter and ADF are standard in all military variants. A weather radar and the Omega navigation system is optional on the naval variant.
The Dhruv was originally powered by a pair of TM333-2B turbo shafts developing 746 kW (1000 shp) from Turbomeca of France. This was later switched to the LHTEC CTS800-4N turbo shaft (from the then Allied Signal of USA - now Honeywell) developing 970 kW (1300 shp). The more powerful CTS800-54 turbo shaft developing 1235 kW (1656 hp) was offered as an option. However these engines were embargoed by the US, for imposing sanctions on India for her nuclear tests in May 1998. Connections were re-established with Turbomeca and the TM333-2B2 engine was selected, developing 825 kW (1100 shp) at take-off, with growth potential to 900 kW (1200 shp) for subsequent versions and features full authority digital electronic control (FADEC).
AIN Online reported in February 2004 that Turbomeca will supply 318 TM333-2B2 engines to HAL for the series production. The aviation journal also stated that Turbomeca has agreed to increase the offsets associated with this deal by transferring more work to HAL, which will now produce the engine's turbocharger and other accessories, including the fuel systems. HAL will also be securing repair licenses for the engines.
Hindustan Aeronautics Limited is going in for a new engine, which will improve its performance in high altitude. Christened Shakti, it will be between 12 and 15 per cent more powerful than the existing TM-333 engine and increase its payload capability by around 300 kg. The new engine has been developed in collaboration with France, where it has undergone tests.
The 21st production aircraft delivered to the Army, will be the first with a glass cockpit and weapons systems integrated. The Army's WSI helicopters will feature a chin-mounted, three barrel 20mm gun from Lockheed Martin and four pylons - each having two hard points - which will enable it to carry eight Nag anti-tank guided missiles, four 68mm or 70mm rocket pods or four tube-launched air-to-air missiles.
