How Indian Army Is Combining Soft Kill And Hard Kill Against Drones With Upgraded Vintage L-70 Guns

Recently, the Indian Army finished the preliminary trials of a modified version of L-70 — the World War-2 era anti-aircraft gun — against drones.

On 21 September, the army tested out the gun at the Army Air Defence College on the seafront at Gopalpur, Odisha, and successfully intercepted a 0.6-metre wide commercially purchased drone.

Part of a project started around a year ago by the Army Air Defence Corps, this is reportedly the first test of the upgraded L-70 against small drones. It fuses the army’s in-service L-70 air defence gun and a counter-drone system made by a Hyderabad-based private player Zen Technologies Ltd.

The company's Zen-Anti Drone Air Defence Systems (ZADS) variant is primarily a "soft kill" system. It detects and jams radio frequency emissions from the drone between 10 metres and 10 kilometres. On the other hand, L-70 uses a "hard kill" system where it physically destroys the target. Both are connected through a customised hardware interface.

The commercially obtained drones are hard to detect by the existing ground-based air defence radars because of their small size. The ZADS possesses a radio frequency detector which indicates the direction of the approaching drone; the day and night camera align itself towards the target and zoom search its approximate range.

The target coordinates so generated are passed on to the L-70 gun which receives the coordinates in ‘remote’ mode, aligns itself towards the target allowing the operator to lock on and fire. All this happens in a matter of seconds.

“This system will be more effective against swarm drones, because the upgraded gun can spew out predictive fire in the future position of the swarm, saturating the area with predictive fire,” Lt general V K Saxena, former DG, Army Air Defence, was quoted as saying by India Today.

The L-70 anti-aircraft gun, the most widely-used air-defence gun in the armed forces, was manufactured by the Swedish arms firm Bofors AB after the Second World War. It was first bought off-the-shelf in the late 1960s and later licensed to be produced by the Ordnance Factory Board (OFB). The army has close to 1,180 L-70 guns in service today.

Around 200 of these have been upgraded using new electrical servo drives, electro-optical fire control system, video tracking and a new air defence radar by BEL under a Rs 575-crore contract some years ago. The upgrades will help the gun tackle low flying helicopters and aircraft. The L-70 guns have to be first upgraded with an electro-optical system before they can be integrated with the ZADS counter-drone system.

This is a cost-effective solution to replace the import of costly anti-drone systems. This way, older guns like the Swedish L-70s and the Soviet-made ZSU-23 guns, can be swiftly upgraded into drone killers. The costs are believed to be in the range of Rs 6 to Rs 8 crore per gun.

Another upgrade in the L-70 is the newer ammunition. For example, the special proximity-fused ammunition manufactured by Bharat Dynamics Ltd (BDL) where each shell is packed with 1,000 fragments of tungsten that are detonated by a proximity fuse.

Now that the preliminary trials are over, the ZADS-L-70 system will be further refined, including a new X-band radar to detect autonomous drones that fly without a link between the drone and the operator.

The trials come amidst a rising threat of cross-border drone attacks. As per government data, 167 drone sightings in 2019 and 77 in 2020 were recorded along the Pakistan border. On 27 June, India witnessed for the first time what is suspected to be a drone attack on a defence installation in the country. The drones dropped and detonated two explosive devices at Jammu Air Force station. Pakistan-based groups have been using drones regularly for the past two years to smuggle drugs, arms, ammunition and fake currency across the border.

Also read: Pakistan-based groups use drones regularly for surveillance, smuggling drugs, arms, fake currency across border