How Active Armor Works

December 31st, 2010 in Current Events by Frank Chadwick

About twenty years ago I read an article by General Donn A. Starry, former head of TRADOC but by then (as I recall) retired. In it he speculated that the Soviets were probably working on electrostatic tank armor. Back then, whenever you read something like, “The Soviets are probably working on a microwave mind control ray,” from someone respectable and well plugged-in, what it generally meant was: “We are working on this, the Soviets must know that, and so they will probably work on it as well just to keep up.” In other words, it told you more about what we were doing than what they were doing.

Electrostatic armor – in theory – surrounds a target with a weak electromagnetic field, while an on-board capacitor stores a whale of a big additional charge. When a heat round detonates, the penetrator is formed from the molten metal of the thin metal sheet lining the front of the shaped charge. This sheet is often made of copper, but in any case it is conductive. When it enters the electromagnetic field, it closes the circuit and the capacitor discharges, zapping the penetrator stream with enough power to vaporize it – or at least really mess it up.

The problem is generating all that electricity to run the bug zapper. You can charge a good capacitor off the tank’s power plant, but that takes time. What if someone fires a second round at you right away?

At about the same time folks were doing a lot of work on directed energy weapons as missile defense systems and the Soviets were getting pretty good at explosive generation of power – an explosion contained in a closed chamber which could produce an almosrt instantaneous spike of electricity. Hmmm, I thought. Put those together and you might have something.

A couple months later I was at a banquet with a bunch of defense and defense industry types. The guys seated across from me were private sector guys working on electronics and I mentioned the whole electrostatic thing and the possible tie-in with explosive power generation. “Have you heard of anyone working on that?” I asked.

The guy across from me paused and looked up for about five seconds, thinking, then shook his head. Back in those days, when someone thought like that about the answer to a question, they weren’t thinking about what they knew; they were thinking about what they could say. He couldn’t say anything, but somebody was either working on or blue-skying the idea.

Nothing much came of the whole electrostatic thing, but the Soviets did roll out a succession of active defense systems. Unlike the Explosive Reactive Armor (ERA) I talked about earlier, these systems do not react to a strike, but actually reach out to kill an incoming round.

The first of these systems was Drozd (Thrust) which consisted of eight small rockets  mounted on the side of the turret, along with a millimeter band radar to detect incoming antitank guided missiles. The system automatically fires a rocket which detonates and produced a cloud of fragments intended to destroy the missile, like a big shotgun shell. The system protects the front 90 degrees of arc of the tank.

Drozd-1 showed up the early 1980s on Naval Infantry T-55s. An improved version, Drozd-2, can engage missiles from about 240 degrees of arc with ten rockets.

Next came Shtora-1, also called an EOCMDAS — because saying “electro-optical counter-measures defensive aids suite” every time you talk about it is just too damned hard. Shtora has a couple electro-optical emitters (i.e. really bright lights) on a mast above the turret, some laser sensors, and a bank of anti-laser aerosol smoke grenades. The guidance system of most wire-guided missiles corrects the missile onto the target. It keeps track of the actual position of the missile in flight by tracking the thermal signature of the missile exhaust or a special IR source. The electro-optical emitters give off a stronger IR signature than the missile, confusing the guidance system into thinking the light above the turret is the missile and correcting the trajectory down, and it continues to do so until the missile flies into the ground. For laser beam-riding missiles, the laser sensor detects the laser designator’s energy and automatically fires a smoke grenade to break the beam. Shtora-1 was introduced in the late 1980s.

The most recent system is ARENA, which works on the same principle as the Drozd; the tank’s radar detects incoming rounds and fires protective fragmentation ammunition which destroys them. ARENA has a better engagement envelope and probably has a higher success rate against incoming warheads. Apparently ARENA is a response to the high tank losses Russian tanks suffered in Chechnya from RPGs, and so is set up to engage both faster missiles and slower rocket-propelled grenade rounds, making it pretty effective against just about everything but a long-rod depleted uranium penetrator from a main battle tank. Financial constraints have kept ARENA from mass-deployment, but the Russians have developed an export version (ARENA E) and are hawking it pretty hard. Don’t be surprised to see it turn up in some other armies fairly soon.

It’s interesting the west has done so little in the active armor field, but in part this is due to how successful we have been with more traditional armor systems. Considering how good some of the new hand-held anti-tank rocket launchers are, we might want to rethink that.

About the Author: The major landmarks in Frank's historical interests range from ancient Persia through the Crimean War, World War II, and the modern U.S. Armed Forces, with a lot of stops in between. Frank is fascinated by the unusual, the overlooked, and the surprising. He is the New York Times number one best-selling author of the Desert Shield Fact Book (1991) and he is currently writing an historical novel on Alexander's conquest of Persia – from the Persian point of view.

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2 Responses to “How Active Armor Works”

  1. komgrit said:

    Is this technology being use in Afganhistan?

  2. Brian King said:

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