The HAL Rotary Wing ‘Lightweights’
An excellent example of Made in India initiative, HAL Dhruv ( Polar Star) Advanced Light Helicopter (ALH) has been developed indigenously by the Helicopter Division of the government owned Hindustan Aeronautics Limited (HAL). It is a light multirole and multimission helicopter for Army, Air Force, Navy, Coast Guard and civil operations, for both utility and all weather attack roles. Other helicopters are discussed as well.
An excellent example of Made in India initiative, HAL Dhruv (Pole Star) Advanced Light Helicopter (ALH) has been developed indigenously by the Helicopter Division of the governmentowned Hindustan Aeronautics Limited (HAL). It is a light (5.5 tonne) multirole and multi-mission helicopter for army, air force, navy, coast guard and civil operations, for both utility and all weather attack roles. 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 Weapon System Integrated (WSI) Mk IV known as Rudra. HAL has produced more than 300 Dhruv helicopters till October 2020, for Indian Armed Forces and exports. Also the fleet of the Indian Air Force (IAF) Display Team, Sarang (Peacock) includes the Dhruv helicopters.
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 740 kW take-off power.
A more powerful engine for the Dhruv, the Shakti ( Ardiden 1H) rated at 900 kW 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 maximum fuel capacity is 1,400 litres and the fuel system includes cross feeding and fuel dumping.
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 hinge less main rotor can be manually folded. The blades are mounted between cruciform-shaped carbon-fibrereinforced plastic plates on a fibre elastomer constructed rotor head. The tail section features bearing less 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.
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 ( GPS), a Doppler navigation system, distance measuring equipment, a true air speed indicator, automatic direction finder,
a heading reference system, radio altimeter, Very High Frequency 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 High Frequency (HF), Ultra High Frequency (UHF), and Very High Frequency (VHF) radio communications. Israel Aerospace Industries (IAI) developed an integrated helicopter avionics suite for the Dhruv, including daylight and thermal imaging cameras, electronic warfare suite, and observation and targeting devices. As already stated, the ALH is also outfitted with anti- resonance vibration isolation system, Full Authority Digital Electronic Control (FADEC), and an automatic flight control system.
In December 2006, Nexter Systems (formerly Giat) was awarded a contract for the installation of the THL 20 20 mm gun turret on Rudra helicopters. The turret is armed with the M621 low-recoil cannon and is combined with a helmet-mounted sight. Rudra has stub wings fitted to carry up to eight anti-armour missiles, four air-toair missiles or four rocket pods for 70 mm and 68 mm rockets. The Rudra WSI variant also has FLIR Forward-Looking Infra- Red (FLIR), Charge Coupled Device (CCD) camera and a target acquisition system with thermal sight and laser rangefinder.
The countermeasures suite includes 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.
Designed and developed with seamless airborne operations in support of ground troops at high altitudes and holding the distinction of the first attack helicopter to land on Siachen, the maiden flight of Hindustan Aeronautics Limited Light Combat Helicopter ( LCH) took place on 29 March 2010 marking successful culmination of three years of design and development efforts by Rotary Wing Research & Design Centre (RWRDC) of the Helicopter Complex and appropriately named ‘Tiger Bird’ perhaps inspired from exceptional high agility and the design painted on the prototype. Projected to meet the requirements of the Indian Air Force and the Indian Army (they are likely to order 65 and 114 units respectively) plus significant export potential, the LCH is being developed as a dedicated attack helicopter derived from the Advanced Light Helicopter (ALH) Dhruv and to be fitted with weapons and special mission systems and having a crashworthy wheel landing gear. In addition to the primary anti-armour role the rotary-wing platform will play the critical roles of escort to special heliborne
operations (SHBO), support of Combat Search & Rescue (CSAR) operations, and armed aerial scouting duties. The LCH was declared ready for production in February 2020 with a LCH Production Hangar established at HAL’s Helicopter Division in Bengaluru. The new hanger will “augment capacity to reach the peak production of 30 helicopters per year”, stated HAL Chairman and Managing Director R. Madhavan in an Indian defence ministry statement.
The LCH inherits many technical features of the Dhruv including its rotor system transmission, power plant, hydraulics, IADS, and avionics. The features that are unique to LCH are its sleek and narrow fuselage, exterior covered by canted flat panels to minimise Radar Cross Section (RCS), an integrated dynamic system, including a hinge less main rotor and bearing less tail rotor, which works in conjunction with an anti- resonance isolation system to dampen vibrations, tri-cycle crashworthy landing gear, tandem cockpit, self-sealing fuel tanks, and aerofoil shaped stub wings for weapons, armour protection, Nuclear, Biological, Chemical (NBC) protection and low visibility features which make the LCH “lethal, agile and survivable.”
Notably the flight controls and hydraulics of Dhruv have been redesigned for the LCH. An indigenous Automatic Flight Control System (AFCS) have been designed by HAL. The helicopter is powered by two HAL/ Turbomeca Shakti- 1H1 turboshaft engines fitted with Infra-Red (IR) suppressors, each of which can generate up to 871 kW and can run for up to 3,000 hours without maintenance. It features a Full Authority Digital Electronic Control ( FADEC) system, which decreases the work of the pilot by automatically counting engine cycles. The LCH has a cruise speed of 260 km/h, a maximum speed of 275 km/h and a climb rate of 12 m/s to a service ceiling of 6,500 m. LCH has an operational range of 550 km and a ferry range of 700 km.
Fitted with a chin-mounted, twin-barrel M621 20 mm cannon on a Nexter THL20 turret integrated to a Helmet Mounted Sight (HMS), LCH armament will include Belgian 70- mm rockets and air- to- air/ air-to-ground missiles and Laser Guided Bombs ( LGB) on the weapon stations. MBDA PARS3 and indigenous Helina with a range up to 7 km are favoured antiarmour weapons. MBDA Mistral-2 Air-to
Air Missiles (AAM) are carried to ensure self-protection during scouting operations and to decimate hostile helicopters and Unmanned Aerial Vehicles (UAV). The helicopter would have day/night targeting systems for the crew including the helmet mounted sight and an Elbit Compact MultiPurpose Advance Stabilisation System (CoMPASS) electro-optic/infrared turret ( being license built in India by Bharat Electronics Limited) consisting of CCD camera/ third generation 3-5 μm ForwardLooking Infra- Red ( FLIR)/ Laser Range Finder (LRF)/Laser Designator (LD). The LRF and LD facilitate measurement of range to the target and guidance to the laser guided missiles respectively. The Digital Video Recorder would enable recording of the vital mission for debriefing purposes.
The turret gun skewing is controlled by the Helmet Mounted Sight ( HMS) of the gunner, who along with the pilot receives adequate inputs from MultiFunction Displays (MFD). The digitally camouflaged LCH is also fitted with a Saab Self-Protection Suite consisting of Radar/Laser warning receivers and Missile Approach Warning Systems ( MAWS) and Countermeasures dispensing system. It is planned to integrate IR/Laser missile jammers on the helicopter. Another addition is a Data Link for Network-Centric Warfare ( NCW) operations facilitating transfer of the mission data to the other airborne platforms and ground stations operating in the network, thus facilitating force multiplication. The LCH is designed for low detection (visual, aural, radar and infrared) and includes armour protection of critical areas.
A 30 minute dry running capability of the gear box is a built in-feature to survive after any ballistic hit to the transmission system. Crashworthiness features are built into the wheel landing gear and main structure while dual redundant systems also enhance effectiveness of helicopters in the battlefield environment. The performance features of the LCH including rate of climb, cruise speed, service ceiling are comparable with those of contemporary helicopter types such as the Agusta A129 ‘Mangusta’ and Tiger. Development costs of the LCH have been “relatively low” compared to that of other helicopter types in its class, ensuring lower unit costs. “LCH design is optimised to ensure ease of maintenance with improved reliability of all the onboard systems to keep the life cycle operating costs low as well,” stated a HAL designer.
HAL Light Utility Helicopter (LUH) is a new-generation rotorcraft being designed and developed by Hindustan Aeronautics Limited for the Indian Armed Forces to replace the combat-proven Cheetah and Chetak helicopters in service with the Indian Air Force and the Indian Army. It is capable of performing multiple missions such as surveillance, reconnaissance, rescue, medical evacuations, and cargo and troop transport. The helicopter’s cabin and airframe are made of composite material. It features two access doors and windows on port, as well as starboard sides of the hull for the entry and exit of passengers. The next-generation helicopter is also fitted with high-capacity skid-type landing gear.
The LUH is powered by an Ardiden 1U (Shakti) engine designed by Safran. The two-stage turbine engine develops a maximum power of 1,058 kW enabling the rotorcraft to perform search-and-rescue missions, long- range flights, and hover operations. The maximum continuous power output of the engine is 912 kW. The Ardiden 1U engine integrates a two-stage centrifugal compressor along with a singlestage gas generator turbine equipped with single crystal blades. It also features a reverse flow combustion chamber, an integral oil system, and a dual-channel FADEC system. The engine can be operated in Auxiliary Power Unit (APU) mode, which enables power supply for all the lighting, electronic and communications systems aboard the helicopter.
The LUH integrates a glass cockpit equipped with Multi-Function Displays (MFD). The smart cockpit display system presents key flight data on LCD screens. The new-generation helicopter also features auto- pilot and helmet- mounted display system.
Additional equipment includes a rescue hoist for search-and-rescue operations, cargo sling and stretchers. The helicopter also features an emergency floatation system to remain afloat in the event of crash landing on water. The maximum take-off weight of the helicopter is 3,150 kg.
The helicopter is capable of performing in high-altitude areas such as the Himalayas. It has a service ceiling of 6,500 m and can perform manoeuvres with ease due to the sufficient power generated by the engine. It is capable of carrying payloads weighing up to 500 kg. The LUH can attain a maximum speed of 235km/h during a level flight at the sea level. It can endure up to a range of 350 km, which can be extended to 500 km with the integration of internal fuel tanks.