Term of the day

High Explosive Squash Head (HESH) or High Explosive Plastic (HEP) Round

This is a type of anti-tank ammunition in which the explosive is contained in a thin-walled projectile which deforms on contact with the target, allowing the explosive to spread. A base fuse then detonates the explosive which sends shock waves through the armour. The shock waves are reflected from the internal face of the armour and when they meet the next incoming wave, the resulting wave front causes the armour to fracture. This type of ammunition is not velocity dependent as it relies on chemical energy to achieve its effect.

Term of the day

High Explosive Anti-Tank Round

A type of chemical energy ammunition (i.e., ammunition where the penetrative power is generated by explosive energy rather than by kinetic energy) fitted with a high explosive anti-tank (HEAT) – or hollow charge – warhead. The HEAT warhead is not velocity dependent. In order to achieve penetration, the limited amount of explosive is shaped into an inverted, rearward-facing cone lined with a metal such as copper or some other ductile material. When the charge is detonated by a nose fuze, a jet of high energy gas and vaporised metal is projected forward at speeds, typically, of 6,000 m per second. This plasma jet acts like a cutting torch.

Term of the day

Armour Piercing Fin-Stabilised Discarding Sabot Round

A type of kinetic energy ammunition where a sub-calibre penetrator of heavy material is surrounded by a light weight 'pot' or sabot which supports the penetrator in the barrel. The use of the sabot ensures that the largest possible base area is presented to the propellant gases over which pressure can be exerted. The sabot falls to the ground a few hundred metres from the barrel, leaving the sub-calibre penetrator to continue to the target.

Term of the day

Stadiametric Ranging

A method of ranging in which markings in the field of view of the operator's sighting system are compared with an assumed standard dimension of the target - for example, the vehicle's height.

Term of the day

Fixed Gun Tank

This is a turretless tank that features a gun fixed to its chassis rather than installed in a turret. This design offers a simple method of automatic loading and would permit a longer barrel to be used than would be possible in a turreted tank of similar size and weight.

Term of the day

Autoloader

Autoloader (also called automatic loader) is a mechanical system to load the main armament and so eliminate one member (human loader) from the fighting vehicle's crew.

Term of the day

Thermal Imaging Sight (Thermal Imager)

A sight based on the use of infra-red technology to produce a picture of the heat signature of an object against its background. It is a passive system which detects infra-red (IR) radiation emitted by the target and converts this into an electrical signal which can be used to create a visual image.

Term of the day

Main Battle Tank

Originally, the battle tanks were divided into three groups – heavy, medium, and light. However, in the post-war period, with the medium tanks having almost reached the capabilities of heavy tanks while remaining in the same weight class, the medium and heavy tanks were united into one group – main battle tanks (MBT).