Dhruv ALH

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Specifications Table
Origin	India
Type	Advanced multi-purpose light helicopter.
Flight Accomodation	Two crew 12 passengers (normal) or 14 in a high-density configuration or six in a VIP layout. Length
Height	4.98 meters.
Dimensions
Rotor Diameter	43 ft 3 3/4 in both
Fuselage Length (including tail rotor)	42 ft 3 3/4 in
Weights
Empty	2502 kg ( 5511 lbs.)
Maximum	4510 kg (9920 lbs.)
Design	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. Dhruv has been designed to carry underslung bulky loads to inaccessible locations. The Dhruv has a four-blade hinge-less main rotor with advanced aero foils and swept back tips, a fibre elastoner rotor head with blades held between a pair of CFRP star-plates, a manual blade folding & rotor brake standard, a four blade bearing-less crossbeam tail rotor on starboard side of fin, a vibration damping by anti-resonance isolation system compromising four isolator elements between the fuselage and the main gearbox, a fixed tail plane and an integrated drive system transmission. The naval variant of the HAL Dhruv also has a retractable tricycle gear, a folding tail boom, a harpoon deck-lock, pressure refuelling, fairings on fuselage sides to house the main wheels, flotation gear and batteries.
Avionics	Communication radio (U/UHF, HF/SSB and standby UHF modes), IFF and intercom. SFIM for axis AFCS, Doppler navigation system, TAS system, radio altimeter and ADF. A weather radar and an Omega navigation system is optional. The Navy and Coast Guard variants feature a surveillance radar, a forward looking infra-red radar, a loud hailer, cabin-mounted gun troop seats and a life raft among other equipment required for various mission requirements. Engine: 2 TM333-2B2 turbo-shafts developing 825 kW (1100 shp) at take-off, with growth potential to 900 kW (1200 shp) for subsequent versions. A MoU (Memorandum of Understanding) was signed on 12 September 2000 between HAL and Turbomeca to develop a more powerful turbo-shaft. Called Shakti in India and Ardiden 1H in France , this new turbo-shaft will be available for flight tests in 2003 and certification by 2005.
Payload	14 pax (1,500 kg. max.)
Speed
Maximum	290km/hr or 180 mph
Maximum cruising speed	253km/hr or 157 mph Climb Rate
Range	With 1,500 kg. (3,300 lbs.) payload- 414 km. (249 miles/ 216 nautical miles) With max. fuel and 20 min. reserves- 810 km. (497 miles/ 431 nautical miles)
Ceiling	5990 metres ( 19,680 feet)
Armaments	The Army/ Air Force versions can be fitted with * 8 3rd generation Nag Anti Tank Guided Missiles * 4 Air-to-Air Missiles or 4 x 68mm rocket pods * 20mm gun in under fuselage turret The Naval Version can be fitted with * Cabin side pylons for 2 Torpedoes/Depth Charges or 4 Anti Ship Missiles like Sea Eagle or SS-N-25 (3M-24E) * 20mm gun * Slung load for mines In addition, the Gunship version will carry * Anti radiation missiles * Cluster and Iron Bombs * Grenade Launchers
Stores	Max. External Stores Load : 1500 kg. (3307 lb.) for Naval Dhruv
Self Defence	* Undetermined flare and chaff dispensers. The Navy version will also have RWR and Jammers. * The two TM 333 2B2 engines are widely spaced to reduce the possibility of one damaged engine infecting the other but if the Dhruv cannot return to base, crashworthy seats will protect the crew. The helicopter is also said to be able to ditch and float in water up to sea state 5/6, although an emergency floatation system is provided. * As the aircraft was designed for defence applications initially, survivability has been a high priority. Thus, low radar, thermal and acoustic signatures have been a design objective, while extensive use of composites provides optimum crashworthiness and battle damage tolerance, as well as easing repair. * There are adequate safety margins in the event of single engine failure during takeoff, landing or other operations close to the ground.
Cost	Rs.24 Crore (Rs.240 million)

IMAGES/PHOTOGRAPHS



"Dhruv"-- the Advanced Light Helicopter, has been indigenously designed and developed by the Rotary Wing Research and Design Centre, Hindustan Aeronautics Limited (HAL), and produced by Helicopter Division, HAL, under the stewardship of Mr. Ashok Baweja, Director (Design and Development) who recently took over as the Chairman of the company.

Dhruv is a state-of-the-art twin engined new generation helicopter in the 4.5 to 5.5 ton weight class. It is a multi-role, multi-mission helicopter with a wide range of military and civil applications, and is presently in series production stage.

Dhruv is designed to fulfil a variety of roles like casualty evacuation and aircrew rescue, communication duties, carriage of underslung loads, logistic support, reconnaissance, air observation post, off-shore operations, training, search and rescue, anti-smuggling, anti-pollution and anti-poaching, anti-tank, close air support, air to air combat, scout, anti-submarine warfare (ASW) and anti-surface vessel (ASV).

Dhruv employs state-of-the-art technology and is designed to operate in high and hot conditions, cold weather and saline environments.

It is highly agile and manoeuvrable, has high lift and speed capability and excellent hot and high performance, low noise and vibration levels and high payload capacity.

Dhruv incorporates a number of advanced technology features. Extensive ground and flight test have been carried out to validate the design parameters. The main rotor is hingless that gives this helicopter excellent maneuverability, agility and is easy to maintain .The tail rotor is bearingless. This gives superb tail rotor power even at altitude and is easy to maintain. It is possible to carry out spot turns up to 60 deg /sec rate even at altitude with adequate reserve of control margin. The advanced blade profile of the main and tail rotors make the helicopter very silent with very low external noise, give high speed and efficient lift. The advanced blade profile also gives low drag, high CL max, high drag divergence Mach.Number, low pitching moment, good hover performance and low control loads. To demonstrate the high altitude handling capability of Dhruv, in Fig1 the time history of lateral cyclic control response is shown. At 20,000ft AMSL half-inch control in put was given at Vh, The roll rate rises immediately, but is very nicely damped. The role angles are therefore easily controllable. Similarly Fig 2 shows the normal acceleration and pitch rate response to half inch longitudinal cyclic in put at 20,000ft AMSL at Vh, The response of the helicopter is better than the MIL Spec requirement by an order of magnitude. This shows that the helicopter is very maneuverable and agile even at altitude. There is adequate reserve of control margin at all weight and CG conditions. The helicopter is cleared to land on slopes up to 10 deg in any direction.

Dhruv has a composite structure forming 60 per cent by surface and 30 per cent by weight, crashworthy and energy absorbing crew seats and bottom structure and turbo-shaft engines with free power turbines and Full Authority Digital Electronic Control (FADEC). These technology features result in a highly performing helicopter with low number of parts leading to high reliability and reduced maintenance, increased safety, high resistance to corrosion, high damage tolerance and, life cycle cost and multi-mission capability.

Dhruv compares extremely well with other contemporary helicopters of its class. It exceeds the performance of most of its competitor helicopters. In terms of commercial parameters, Dhruv ALH stands superior in many respects.

The users (Indian Air Force, Army, Navy and Coast Guard) have conducted extensive field trials in all the environmental conditions. These include trials in the high and hot conditions in the sandy deserts of Rajasthan, high and hot & cold conditions in the snow clad mountains of Himalayas and deck landing trials onboard Coast Guard and Navy ships. Now they are being used extensively in these roles and missions with great customer satisfaction.

Dhruv with wheeled undercarriage was awarded

SOURCES/REFERENCES

Bharat Rakshak
ACIG

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