Farnborough Air Show

HAL’s Dhruv shows solid performance

 - November 16, 2006, 6:57 AM

India’s Hindustan Aeronautics Ltd. (HAL), headquartered in Bangalore, has brought two examples–one civil production aircraft and a military prototype–of its indigenously designed Dhruv helicopter to show here at Farnborough International. Formerly known as the Advanced Light Helicopter, the 12,210-pound mtow Dhruv (a Hindi word which transliterates to “the pole”–referring to the North Star) has been in development since at least as early as November 1984 when HAL revealed the basic specifications of the helicopter. At that time MBB of Germany, later merged with France’s Aerospatiale to form Eurocopter, supported the program and indeed the Dhruv bears a strong resemblance to MBB’s smaller BK 117 model.

Now certified by the Indian civil aviation authority (DGCA) in accordance with U.S. FAR Part 29 and additional DGCA rules, the Dhruv fleet of five prototypes and 64 production aircraft has logged more than 10,000 flight hours. Aircraft are in operation with the Indian army (whose initial letter of intent for 300 units launched the program) and the country’s air force, navy, coast guard and a few civil operators in India, Nepal and Israel. India’s state-owned Oil and Natural Gas Corp. has ordered three and Malaysia, Indonesia, Peru, Venezuela and Chile have expressed interest.

The basic price of the civil version varies with mission, but runs at about $6.5 million to $7.4 million, according to C.D. Upadhyay, HAL chief test pilot (rotary wing). That low acquisition price, when compared with other helicopters in its class such as the Bell 412, Eurocopter EC 155, Sikorsky S-76C+ and AgustaWestland AW139, is an obvious selling point in the Dhruv’s favor, but its lack of U.S. and European approvals has likely inhibited its attraction outside India. Though impossible to predict, these approvals would seem to be on a distant horizon as government-to-government bilateral agreements on the approval procedure must be obtained before revalidation of the ALH/Dhruv type certificate by the American and European aviation authorities can take place.

Solid Feel and High-altitude Performance

Aviation International News flew the civil example of the Dhruv here at Farnborough shortly before the opening of the air show. Multi-use capability coupled with a joint military/civil design philosophy necessarily dictates a solid, functional aircraft and so it is with the Dhruv.

In flight and in hover, the Indian aircraft demonstrates the stability of a heavier helicopter, even in gusty wind conditions. The four-axis autopilot provides impressive hands-off flight while the hingeless main and bearingless tail rotors contribute to a noticeably smooth ride.

“The Dhruv’s performance really shines above 10,000 feet, when compared to similar helicopters,” said N.S. “Krish” Krishna, deputy chief test pilot (rotary-wing), who commanded our flight. We stayed below 1,500 feet, hardly straining the Dhruv’s fadec-equipped Turbomeca TM333 2B2 engines (1,082 shp takeoff and 987 shp max continuous power at sea level, ISA).

HAL (Chalet K9-10) had worked with LHTEC to incorporate the more powerful 1,656-shp CTS800-54 and 1,362-shp–4N engines, but India’s nuclear weapons testing led the U.S. to block delivery of the engines in 1998. Now HAL and Turbomeca are developing a new turboshaft engine, which is expected to be available later this year. Called the Shakti, the engine will provide 1,432 shp for takeoff and 1,221 shp max continuous power (sea level, ISA).

While the military prototype Dhruv shown here is equipped with a glass cockpit designed by HAL and IAI, the civil example has the approved “steam gauge” instrumentation, which provides a functional though slighted dated feel. And although Turbomeca’s fadecs provide one-button engine starts, the plethora of switches and circuit breakers for other systems require checklist procedures more reminiscent of older designs. Newer helicopters have more streamlined procedures.

Nevertheless, the Dhruv gives an overall impression of a robust helicopter that has benefited from a long development program and can now perform a plethora of military and civil missions.