Cracked Past

Reactive Revolution: Meet the Pulverisers

Pam, Barnie and Bam Bam may sound harmless enough. In fact, they are new munitions which will tear apart rock and concrete with astonishing ease - the “most effective… concrete damaging warhead known to date,” thanks to the power of reactive materials.It’s surprisingly hard to damage solid rock with explosives. Rock has tremendous compressive strength, so an explosion from outside has relatively little effect. To really break it up, you need to have the explosion inside the rock, as it’s tensile strength is much lower and it can be pulled apart. For centuries, miners have used the technique of ‘drill and blast’: make a deep, narrow hole in the rock face, fill it with explosive, and stand well back. These days, the drills are powered and automated rather than being steel driven by a sledgehammer, but the concept is the same.

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When you’re carrying out demolitions under combat conditions, the type of drilling carried out by miners is not much of an option - even the most modern equipment is heavy and cumbersome, and drilling is still a slow process. So military demolitions rely on using large explosive charges.

That was, until the development of the Penetrating Augmented Munition, or PAM, which uses a shaped charge to drill the initial hole, then a second charge fires explosives into the hole:

The PAM is a multi-stage munition as follows: a Tandem Forward Charge (TFC) which provides a pilot hole in the target, a Follow Through Charge (FTC) which buries itself in the target and then detonates, a Propulsion System which accelerates the FTC so that it will penetrate to the proper depth in the target, and an Electronic Fuzing System (SCS) for the initiation of the FTC propulsion, the FTC, and the TFC using Explosive Foil Initiators (EFIs).

It is several times more effective than to the alternative of bulk explosive:

The PAM replaces 200lbs of C4, and decreases volume from 4,500 cubic inches to 400 cubic inches. It reduces mission time from 3+ man-hrs to 2 man-mins, and requires only one person to defeat each target vs. seven people using conventional explosives.

But PAM is complex, with no less than four separate explosive charges and fuzes, all of which have to work perfectly in the right sequence without damaging each other ion the process. There’s a much simpler and even more devastating alternative: a reactive jet shaped charge.

Normal shaped charges involved explosive surrounding a hollow cone (known as a liner) made of copper. When the explosive detonates, the cone is converted into a high-speed jet which does the damage. But if you replace the copper with reactive material, which releases energy as it is driven forward, it has much greater destructive power. Penetration is not increased, but damage to the material being penetrated is greatly enhanced.

ARDEC, The US Army’s Armament Research, Development and Engineering Center at Picatinny, NJ has been working on this concept for some years.

The first development was Barnie, which is described as a “unitary demolition warhead.”Instead of of PAM’s multiple charges, it simply has a single shaped charge with a reactive liner. Barnie warheads were tested with several different reactive mixtures, and showed that they performed far better than normal liners. The material could be selected to produce either cratering (suitable for tasks such as destroying roads or runways) or deep damage (for demolitions).

Barnie tests used 81mm scale models. The next step was to build a full-sized, 40-pound, 220mm warhead, known as Bam Bam.

“These Unitary Demolition Warheads (UDW) produce an energetic shaped charge jet that releases its energy inside of the target, producing extremely large amounts of damage to concrete, masonry or geologic material targets never previously achieved from a shaped charge warhead.”

The forty pound weight was selected so that as with Pam the warhead could be carried and emplaced by a single soldier.

Bam Bam warheads were subsequently press loaded with LX-14 explosive and experimentally evaluated agains

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