Wednesday, March 23, 2011


Indigenously developed Nag (Cobra) missile will undergo a final round of trials before entering service in the Indian Army’s arsenal. Developed by the Defence R&D Laboratory (DRDL) in Hyderabad, the army is delighted with how the Nag has performed in a series of earlier trials. A senior army officer calls it, “the world’s deadliest anti-tank guided missile (ATGM).

Indian infantry formations urgently want a potent ATGM to handle Pakistani tank forces that now bristle with capable Ukrainian T-80 and Chinese T-85 tanks.

So confident is the army about the Nag that, even before trails are completed, it has budgeted Rs 335 crores for buying 443 Nag missiles, which will be manufactured at the public sector Bharat Dynamics Limited. The missiles will equip Reconnaissance and Support Battalions, mechanised units that locate and destroy enemy tanks.

In trials last summer six Nag missiles were fired at tanks 3-4 km away; each of them hit their target precisely. Next month the Nag must demonstrate its capability at its minimum range of 500 metres.

“Since the Nag travels at 230 metres per second, it has just 2 seconds to align itself to a target that is 500 metres away. But we are confident that the Nag will meet this requirement during the forthcoming trials”, the DRDL’s Officiating Director, Amal Chakrabarti, told Business Standard during a visit to the Hyderabad missile complex.

The Nag is a third-generation (Gen-3), “fire-and-forget” missile; once it is fired, its seeker automatically guides the missile to even a fast-moving tank. In earlier-generation missiles an operator had to guide it all the way, often exposing himself to enemy fire. The world has just a handful of “fire-and-forget” missiles, such as the American Javelin, and the Israeli Spike. The Javelin and the Spike are lighter missiles that can be carried by a soldier; the Nag is a heavier and more powerful missile designed to operate from vehicles and helicopters.

While the infrared seekers of the Javelin and the Spike can be jammed, the Nag’s optical guidance system makes it virtually jam-proof. The indigenous development of an imaging seeker, a highly complex and closely guarded technology, is the Nag’s greatest triumph.

Here’s how it works. Nag missile operators search for enemy tanks through thermal imaging telescopes, which see as well by night as they do by day. Picking up a tank, the operator locks the Nag’s seeker onto the target. A digital snapshot of the target is automatically taken, which serves as a reference image. As the Nag streaks towards the target, at 230 metres per second, the seeker takes repeated snapshots of the target; each one is compared with the reference image, and deviations are translated through on-board algorithms into corrections to the Nag’s control fins, which steer the missile precisely at the target.

This method of firing is termed “lock-on before launch” or LOBL. In the pipeline is an even more sophisticated method --- “lock-on after launch” or LOAL --- for the helicopter-mounted Nag, or HELINA, which can target a tank 7 kilometres away. Since the target will seldom be visible at such a distance, the missile operator launches the HELINA in the general direction of the target. As it flies towards the target, the Nag’s seeker downlinks to the missile operator images of the area ahead; after travelling 3-4 kilometers, i.e. after about 12-16 seconds, the operator will be able to identify enemy tanks. He will lock the seeker onto the tank he wishes to destroy, and the command will be uplinked to the missile in mid-flight. After that, the missile homes in onto the target and destroys it.

The Nag provides its operator with another important tactical advantage. The plume of burning propellant from the tail of most missiles gives away its flight path and allows the target to get behind cover. The Nag, in contrast, is visible only during the first one second of flight, when the missile’s booster imparts 90% of the momentum; after that, a sustainer maintains the missile’s speed, burning a smokeless propellant that is practically invisible.

Acceptance of the Nag missile into service will be a triumphant conclusion to the Defence R&D Organisation’s (DRDO’s) long-delayed, but eventually successful, Integrated Guided Missile Development Programme (IGMDP). Initiated in 1983 by then DRDO boss, Dr APJ Abdul Kalam, the IGMDP set out to develop five missiles: the Agni and Prithvi ballistic missiles; the Akash and Trishul anti-aircraft missiles; and the Nag ATGM. Only the Trishul will have failed to be accepted into service.