While civilian countermeasures to combat malicious drones is moving toward UAV-freezing radio beams, the US Army is taking a more permanent approach. Under development by the U.S. Army Research, Development, and Engineering Center (ARDEC) at Picatinny Arsenal, New Jersey, the Enhanced Area Protection and Survivability (EAPS) system used steerable 50 mm smart rounds to shoot down two drones in recent tests.

The Army says that EAPS is a gun-based alternative to the missile-based Counter Rocket, Artillery, and Mortar (C-RAM) system currently favored by the US military. It was originally designed to counter rockets, artillery, and mortars (RAM), but due to the increasing threat from UAVs the system’s mission was expanded to include drones.

Using a 50 mm cannon, EAPS fires guided interceptor projectiles guided by a precision tracking radar interferometer and a fire control computer. The system tracks the projectile and the target and computes an ideal trajectory correction. A radio transceiver then beams an engagement "basket" at the target for the projectile to home in on. Thrusters on the projectile are used for course correction and as it nears the target a forward-fragmenting warhead with a tantalum-tungsten alloy liner detonates to deal with C-RAM targets, while steel body fragments take out unmanned drones.

"In order to minimize the electronics on board the interceptor and to make it cheaper, all the 'smarts' are basically done on the ground station," says Manfredi Luciano, project officer for the EAPS Army Technology Objective. "The computations are done on the ground, and the radio frequency sends the information up to the round."

On August 19, EAPS underwent final proof-of-principle demonstration tests at the Yuma Proving Ground in Arizona. During the test, it shot down two remotely piloted Outlaw class aircraft built by Griffon Aerospace at a range of 1 km (0.62 mi) and an altitude of 1,500 m (4,900 ft). This replicated the first EAPS shoot down of a loitering aircraft on April 22, but at 50 percent greater range.

According to Luciano, the technology developed for EAPS could one day be used in a newly configured Army or Navy tactical air defense system.