As last month's grounding of flights at Gatwick Airport showed us, drones can cause a lot of problems – and they can even pose a security risk – when they're flown in the wrong places. Engineers with the US Army are developing a countermeasure, in the form of a drone-netting grenade.

The experimental 40-mm grenade was invented by Tomasz Blyskal, Richard Fong and LaMar Thompson at the Picatinny Arsenal in New Jersey.

Individual soldiers could shoot it at rogue drones using M320 portable grenade launchers, while heavy weapons platoons could utilize larger Mk-19 launchers. The former setup could target drones hundreds of yards away, while the latter has an even longer range.

Once the launched device nears an airborne drone, a servo within the grenade releases its ogive (nose) section. This allows a spring-loaded weighted net to be ejected forward out of the grenade's body. That net proceeds to spin through the air, spreading out 6 to 9 meters (20 to 30 ft) to ensnare the drone. The netted aircraft subsequently falls to the ground.

The servo is triggered via a signal from an integrated control board, which can in turn be remotely activated by someone on the ground, or by an onboard proximity sensor.

According to the army, initial tests have shown that the grenade is more effective than other approaches such as drones that net other drones, as no drone-piloting skills are required. Additionally, because one person could carry dozens of the grenades, the system would be better able to take down whole swarms of drones.

British engineering firm OpenWorks' portable SkyWall device also launches projectiles which in turn deploy drone-catching nets.

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