Exploding bombs and shells have been thrown at the enemy for the longest time, using all kinds of explosive materials throughout the centuries. The introduction of high-explosives was a huge leap in the development of this weapon type, starting from Picric acid, through TNT and all the way to the modern RDX based mixtures. The amount of high-explosives used per shell increased drastically over the decades as well, reaching as high as 25% of the total shell weight.
HE – High Explosive
By definition a high-explosive shell includes a steel case, a bursting charge and a fuse. Upon impact the fuse detonates the charge, creating large amounts of high velocity fragments. Contrary to popular belief, these fragments cause most of the damage instead of the blast, at least when used against infantry. As today most armor piercing shells have a bursting charge as well, most shells used are actually a type of HE ammunition.
HEAT – High Explosive Anti Tank
Also referred to as shaped charge ammunition, in these cases the high-explosives are combined with a conical liner (a cone-shaped hollow object), in order to create a stream of concentrated particles. As this stream travels with hyper-sonic speed, it simply pushes the opposing material out of its way, applying kinetic damage. (Contrary to popular belief, the stream is not a super hot liquid that burns its way through the armor.) This type of ammunition is extremely effective against regular steel armor, but is negated largely by composite- or reactive armor. The effectiveness and popularity of HEAT ammunition changed tank design forever. You can read more about it in our dedicated HEAT article.
HESH / HEP – High Explosive Squash Head / High Explosive Plastic
HESH being the British term and HEP being the US term, this ammunition type is a highly efficient anti-tank solution, that’s also considered to be the most effective shell type against brick and concrete buildings. It consists of a special thin walled shell, loaded with a plastic explosive that simply flattens on the surface of the armor (or wall) upon impact, before being detonated by a delayed fuse. The shell is not designed to penetrate the armor, instead the focused blast creates a powerful shock wave, that simply tears (spalls) metal pieces off the inner wall of the armor, causing internal damage to modules and crew. Spaced armor is however the Achilles heel if HESH, as it completely negates its effect, if the outer armor is capable of withstanding the explosion itself.
SAPHE – Semi Armor Piercing High Explosive
Modern HE shells today are more of a mixture of the traditional AP and HE variants. These shells have a decreased anti-armor capability compared to dedicated armor-piercing ammunition, but have a much higher high-explosive content (up to 15%) for improved anti material / personnel effect. Further benefit of this ammunition type is that it can be used effectively against a variety of targets, thus tank crews do not have to bring a whole selection of different HE ammunition to combat.