C-RAM

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.

enhanced-protection-1

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.

Counterbattery!

We’re used to seeing clips and stories of artillery pummeling enemy fortifications or troops. Goodness knows we’ve shown more than a few ourselves.

But one of the major roles of artillery is attacking an enemy’s artillery. This counter artillery role is known as counterbattery (even when engaging formations larger than a battery).

In the days of the American Civil War, counterbattery was directed visually. But in the era of breechloaded guns with smokeless powder and explosive shells firing from over the horizon, locating enemy batteries was infinitely more difficult.

Forward observers could spot some mortar and light artillery batteries. And there were acoustical detection devices. In fact, from about 1916 well into the 1950s, sound location, or MASINT (Measure And Signature INTelligence)  was the primary means of locating enemy firing batteries. By measuring the difference in the Time of Arrival (TOA) of a gun blast along a baseline of sensors, the enemy location could be triangulated. Similarly, lines of bearing from multiple points could point to an enemy battery. Calculating the firing point could take as little as three minutes.

Meanwhile, at the beginning of World War II, the US Army was just staring to explore the possibilities of using radar to control anti-aircraft fire. The first Army radars operated with frequencies in the meter range. That was relatively adequate for long range search, but for precise control of gunfire, it was rather disappointing. When the British shared the discovery of the cavity magnetron, the US was able to very quickly develop centimetric wavelength radars. One in particular, the SCR-584, was extremely effective. Not only was it very precise, it was quite versatile as well. It could act as a search radar out to respectable ranges, as much as 35 miles. Incredibly, given the infancy of radar development, it was capable of automatically tracking targets within about 18 miles.

The SCR-584 was so fundamentally sound, during the development of the M1 90mm Anti-Aircraft gun it was intended to work with, the radar was used to confirm the ballistic profiles of the shells fired from the gun. Ballistic tables were normally devised by computers- that is, hundreds of women with slide rules- mathematically. By confirming the calculations with empirical observation provided by the SCR-584, the complete tables were validated more quickly than normally possible. That is, the 584 was precise enough to track a 90mm shell in flight. By measuring the range and angle from the mount to the shell over a handful of times during the flight of the shell, the ballistic parabola could be derived.

It didn’t take long for some bright operators to realized that if you could determine the ballistics of an outgoing shell, you could also determine the ballistics of an incoming shell. And with a map and a little math, you could plot the parabola back to its point of origin, that is, the enemy firing battery.

Having discovered that radars could be used to track artillery fire, it wasn’t long before the service sought out a radar optimized for the mission. Nor was the US Army the only force to develop a dedicated counterbattery radar. Today, almost every army has at least some counterbattery radar capability.

For the past 30 years or so, the US Army and Marines have fielded the TPQ-36 and TPQ-37 Firefinder radars in the Target Acquisition Batteries of their artillery units. Recently, the Army has also fielded the TPQ-46 Lighweight Counter Mortar Radar. While the Q-46 does calculate the firing point of enemy radars, it’s primarily used to warn troops of incoming mortar and rocket fire. It can also cue the Counter Rocket Artillery Mortar (C-RAM) system to intercept mortar rounds.

[youtube https://www.youtube.com/watch?v=euwf6TA9dIc]