Dhruv (Pole Star) advanced light helicopter (ALH) is developed indigenously by the Helicopter Division of the government-owned Hindustan Aeronautics Limited (HAL).
It is a light (5.5t class) multirole and multimission helicopter for army, airforce, navy, coastguard and civil operations, for both utility and attack roles by day and night.
The helicopter, which is built to FAR 29 specifications, entered series production in 2000. Its prime variants are classified as Dhruv Mk-I, Mk-II, Mk-III and Mk-IV or Weapon System Integrated (WSI).
HAL has produced 228 Dhruv helicopters till March 2017, of which 216 are operational with the Indian Armed Forces.
Orders and deliveries of the Indian helicopter
In all, 18 Dhruv helicopters were delivered to Indian Defence Forces in 2000-2003 – eight to the army, three to the navy, four to the airforce and three to the coast guard.
The army received its first three Dhruvs in March 2002. By June 2008, 76 helicopters had been delivered to the army and airforce with 159 more on order. The Indian Navy has decided not to place any further orders.
The fleet of the Indian Air Force Display Team, Sarang (Peacock in English) includes the Dhruv helicopters.
In February 2011, HAL handed over five Dhruv Mk-III advanced light helicopters to the Indian Army during the Aero India 2011 Air Show.
In June 2008, HAL received the first export order for the Dhruv with seven helicopters for the Air Force of Ecuador.
In August 2006, Indian Air Force and Coast Guard Dhruv helicopters were instrumental in rescue operations after devastating floods in India. Over 500 people were rescued.
In February 2007, the Dhruv was qualified for high-altitude / low-temperature operations in Kashmir and Jammu.
In August 2007, maiden flights took place of the Dhruv powered by the new Shakti engine and of the weaponised variant of the helicopter.
In September 2007, the Indian Army announced that the Dhruv was ready for deployment to the Siachen sector in the Himalayas. The helicopter was deployed to the high-altitude airbase at Manasbal (Srinagar) and, in October 2007, a Dhruv helicopter flew at a record altitude of 27,500ft in Siachen.
The country’s National Disaster Management Authority (NDMA) ordered 12 Dhruv helicopters equipped with a full medical suite in 2007.
In August 2008, HAL was awarded a $50m contract for supplying a helicopter to the Ecuadorian Air Force and two helicopters to the Peruvian Health Services.
HAL is currently producing 159 Dhruv helicopters for the Indian Army and IAF. In 2017, the company received orders for supplying 73 ALH units in Mk-III and Mk-IV variants to the Army, Coast Guard and Navy.
HAL and Israel Aircraft Industries (IAI) have an agreement to market the Dhruv helicopter worldwide. The helicopter has been supplied to the Nepal Army, the Mauritius Police, and Maldives.
Design of the Dhruv ALH
The Dhruv ALH helicopter is of conventional design and about two-thirds by weight of composite construction. The high tail boom allows easy access to the rear clamshell loading doors.
The four-bladed hingeless main rotor can be manually folded. The blades are mounted between cruciform-shaped carbon-fibre-reinforced plastic plates on a fibre elastomer constructed rotor head. The tail section features bearingless tail rotor.
The helicopter is equipped with an active vibration control system developed by Lord Corporation of North Carolina that uses sensors to monitor on-board conditions and outputs signals to actuators to cancel fuselage floor vibrations.
Cockpit and avionics
The cockpit section of the fuselage is of Kevlar and carbon-fibre construction and is fitted with crashworthy seats.
The navigation suite includes a global positioning system, a Doppler navigation system, distance measuring equipment, a true air speed indicator, automatic direction finder, a heading reference system, radio altimeter, VHF omnidirectional ranger and instrument landing system (VOR/ILS) and marker beacons. The aircraft is equipped with a SFIM Inc. four-axis automatic flight control system.
The communications suite includes HF, UHF, and VHF radio communications.
IAI developed an integrated helicopter avionics suite for the Dhruv, including daylight and thermal imaging cameras, electronic warfare suite, and observation and targeting devices.
The Dhruv Advanced Light Helicopter is also outfitted with anti-resonance vibration isolation system (ARI), full authority digital electronic control (FADEC), and an automatic flight control system.
Weapons and armaments on the Dhruv
The army and airforce helicopters have stub wings fitted to carry up to eight anti-armour missiles, four air-to-air missiles or four rocket pods for 70mm and 68mm rockets.
In December 2006, Nexter Systems (formerly Giat) was awarded a contract for the installation of the THL 20 20mm gun turret on the first 20 Indian forces Dhruv helicopters. The turret is armed with the M621 low-recoil cannon and is combined with a helmet-mounted sight.
A flexible weapons carrying system is installed for transporting the weapons.
WSI versions for the Indian Army are fitted with the Nag anti-tank missile, being developed by India’s Defence Research and Development Organisation (DRDO). The Nag missile has imaging infrared guidance and a range of about 4km. The WSI variant also has FLIR (forward-looking infrared), CCD (charge coupled device) camera and a target acquisition system with thermal sight and laser rangefinder.
The naval variant can carry two torpedoes or four anti-ship missiles.
The Dhruv’s countermeasures suite can include: radar and missile detectors, infrared jammer, chaff and flare dispensers.
Saab Avitronics was awarded a serial production contract in December 2008 for the integrated defensive aids suite (IDAS) self-protection systems for Indian armed forces Dhruv helicopters. IDAS has also been fitted on Rooivalk, NH90 and Super Lynx 300 helicopters.
Advanced light helicopter cabin
The 7.3m³ cabin accommodates several layouts. As a passenger helicopter the cabin accommodates 12 or 14 seats.
The cargo compartment at the rear of the cabin has a volume of 2.16m³.A crew door and a rearward sliding door are installed on each side of the fuselage for the military helicopters.
Clamshell doors at the rear of the cabin provide easy and fast access for loading and unloading cargo.
Configured as an air ambulance the helicopter can carry two stretcher patients and four survivors or medical attendants or four stretcher patients and two medical attendants.
Engines on the Indian multirole ALH
The helicopter has a twin-engine configuration allowing continued flight virtually throughout the flight envelope. The prototype helicopter is fitted with two Turbomeca TM 333-2C or 2B2 engines rated at 740kW take-off power.
A more powerful engine for the Dhruv, the Shakti (which carries the French name Ardiden 1H) rated at 900kW was developed under a cooperative agreement between HAL and Turbomeca and manufactured at Bangalore. Avio was selected to supply integrated dynamic systems (IDS) for the Shakti engine.
The first flight of the Dhruv Advanced Light Helicopter with the new engine took place in August 2007 and it was certified in 2008.
The helicopter is fitted with self-sealing crash-resistant tanks installed under the cabin floor. The fuel system includes cross feeding and fuel dumping systems. The maximum fuel capacity is 1,400l.
Helicopter landing gear
The airforce and army helicopters are equipped with non-retractable metal skid landing gear. All variants of the helicopter are fitted with a tail skid to protect the tail rotor in tail-down landings.
FPT Industries, Portsmouth, UK, supplies the Kevlar flotation bags for the skid and wheeled variants of the helicopter. The helicopter can also be equipped with a life raft.