Although our Army loves mobility, the fact is, in any theater of operations, you simply have to have some fixed bases. Logistics, airfields, maintenance facilities require some sort of base. And in the nature of warfare, fixed installations are tempting targets for indirect fire.  For instance, in both the Iraq and Afghanistan wars, insurgents have targeted bases with a variety of indirect fire weapons. For the most part, these attacks have been primarily harassing fires.  They’re too small to destroy much of an installation, but they’re enough that work has to stop, people have to take cover, and occasionally the enemy gets lucky and causes casualties or hits an important piece of equipment.

In wars past, the tactic to counter these attacks was counter-battery fire. Special radars detect the incoming fire, and by tracking their trajectory, can locate their origin. That targeting in information is sent to the artillery (or helicopter gunships, or what have you), and fires placed on the attacker. But sometimes, that’s simply not possible. For instance, if the attack comes from a protected space such as a mosque, firing back might have worse consequences that simply riding out the attack. It’s hard to win hearts and minds when you’re shelling the locals village and their church.

With advances in technology, and some adaptation of existing technology, the Army has developed systems to actually intercept incoming fire. Under the term C0unter- Rockets, Artillery & Mortars, the Army is testing or actually fielding a family of weapons that defeat, well, rockets, artillery, and mortar shells in flight.

The first fielded system was a derivative of the US Navy’s Mk15 Phalanx Close In Weapon System, or CIWS.

[youtube https://www.youtube.com/watch?v=V2004nrHxa0]

A good start, but the Army is looking at other systems as well. For instance, lasers are maturing enough that a deployable system will soon be a reality.

In addition, the Army is realizing that its monopoly on cheap drones is coming to an end, and enemy forces, either state actors, nor non-state forces will be able to operate drones over our installations. Denying the enemy this intelligence is a critical task, and one that the C-RAM initiative is addressing. One interesting concept we noticed the other day is this mobile 50mm chain gun with guided ammunition.


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.

As an aside, that’s one of the nifty things about the Chain Gun, it’s scaleability. The most common chain gun in use is the M242 25mm. But basic gun mechanism has also been used in 30mm (both the low velocity M230 of the Apache gunship, and the high velocity of the Mk46 intended for the canceled EFV) and even 7.62mm. There’s also a 35mm version. I’ll admit this was the first I’d heard of a 50mm variant. And I wonder if, given the fin stabilization of the guided ammo, is it a smoothbore gun? Heck, it would be fun to see a 60mm mortar version.

And having designed the basic architecture for a guided 50mm round, it should be quite simple to design various different warheads for the rounds, enabling it to be used for other roles beyond just C-RAM. For instance, might we see a variant tailored for ships as defense against cruise missiles or small boat attacks? That would be interesting, seeing the circle completed from the adoption of the sea based CIWS.

7 thoughts on “C-RAM”

  1. Would the old but reliable M2 .50 cal machine gun work just as well? Or does the training component required to make a competent gunner cost more than a guided system that is more fire and forget?

    1. The training required to make a gunner competent to manually engage targets that are human eyes are not capable of detecting or tracking due to a combination of small size, high speed, long range and / or camouflage is … less than practical.

  2. 50mm-60mm Bushmasters on Bradley…. no more stopping for TOW shots? but reloading might be a real pain for the dismounts….. Its all just me daydreaming anyway…

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