A hollow charge, also known as a shaped charge or high explosive anti tank (HEAT) warhead, is a type of explosive warhead used to penetrate heavy armor or thick masonry. In military use they are primarily used in anti-tank weapons, but they also have civilian uses in mining and demolitions.


The first known description of a hollow charge was by the German mining engineer Franz Xaver von Baader in 1792: however, his design could not be built with the technology of the time, as the main explosive used at the time, gunpowder, was a low explosive that could not create the phenomenon.

The first hollow charge weapon to be used in combat was the British No. 68 AT Grenade, a rifle grenade.

HEAT rapidly became the gold standard for anti-tank weaponry, with other round types like HESH falling by the wayside as composite tank armor was adopted.

Later research discovered methods of making hollow charge weapons more effective: a key discovery was that there is an ideal distance from armor for a hollow charge to detonate in order for the jet of material to fully form. To this end, hollow charge weapons started to be equipped with standoff rods to carry their detonator, hugely improving anti-armor performance.

In the 1980s, explosive reactive armor was developed to interfere with hollow charge warheads: this armor functions by detonating on contact and throwing a plate of metal outwards at the warhead, disrupting the formation of the penetrating jet. To address this, most modern warheads are of a tandem-charge layout, with a smaller warhead designed to compromise the ERA and clear a passage for the main warhead. The Russian 3BK-31 125mm tank gun round goes a step further by having three hollow-charge warheads, a precursor followed by two full-size warheads designed to compromise modern tank armor.

Design DetailsEdit

Hollow charges function due to a phenomenon called the Monroe effect or Neumann effect. This is the observation that a hole in a block of explosive will cause the resulting blast to be focused inwards.

The term "HEAT" leads to some misunderstandings as to how these warheads function, with descriptions sometimes claiming their damage mechanism is thermal and they "melt through" armor. This is not the case: the jet created by a hollow charge behaves like a solid, and the damage mechanism is kinetic.

Hollow charges are also used in the creation of explosively formed penetrators: these use a complex series of charges to form a solid dart-like projectile from a sheet of suitable material such as copper or tantalum.

Limitations Edit

Hollow charge warheads are only effective against continuous material: upon encountering a void, the jet will tend to lose cohesion, passing through the hole cut in the exterior rather like water through a spray nozzle. This is why there has been virtually no interest in using hollow charge warheads against ships, since their compartmentalized interiors would naturally compromise such a weapon's functionality.


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