38 · MT 3/2022 Feature whilst having a higher mass effectiveness (meaning that a lower weight of titanium would be needed to stop a 14.5mm round) than RHA, is very prone to spalling. This means that titanium alone could potentially increase the danger to the crew if the vehicle is penetrated. The addition of a spall liner, typically made from materials like aramid fibres, is essential. Aramid fibres are characterised by strong hydrogen bonds between molecules, which means they transfer mechanical stress well. A relatively thin sheet of aramid placed behind the armour of an AFV can catch the spalling and fragmentation of a bullet and either reduce the spall cone’s spread, or stop it from affecting the crew altogether. Armouring Up Protecting modern AFVs is always a balance – a tradeoff with mobility and other factors of the vehicle’s design. However, lethality is typically greater than protection, as it is difficult to protect a vehicle from all angles against all threats. Survivability of the crew after penetration is dependent on a number of elements. Automatic fire extinguishers can limit the impact of exothermic reactions, for instance, or prevent ammunition from cooking off. Spall liners can reduce the spread of spalling or fragmentation created by a penetration. Vehicle design elements such as blow out panels can buy the crew valuable time in evacuating a vehicle after it is hit. Of course, advanced and complex armours, as well as active protection systems, mean that the most technologically advanced AFVs in service today are probably the best protected of all time. Nonetheless, the lethality solutions are also more advanced and capable than they have ever been, even compared with the survivability solutions on offer, which means that considering behind-armour effects is still critical. vehicles or vulnerable elements of larger platforms – radars, sights, and tyres. The Heaviest Machinegun The heaviest machine gun any AFV might encounter is the 14.5x114mm KPVT, manufactured by Russia’s Degtyaryov Plant. The the vehicle-mounted variant of the KPV developed in the 1940s, it fires an armour-piercing incendiary (API) round (the B32) and an API round with tracer – the BZT. Rounds weight 64g and 59.6g respectively, with 1,000m/s muzzle velocities. The B32 is the round against which vehicles protected to STANAG 4569 level 4 must be armoured – and it is a significant threat, featuring a steel core and a penetration performance of 32mm of RHA at a 500m range. This theoretically offers a muzzle energy of 32kJ, compared with just 17kJ for the M2 Browning 12.7x99mm – which has more advanced armour-piercing ammunition natures, however. At a very simple level, the KPVT achieves target defeat through a number of mechanisms. Upon penetrating armour, the projectile will break into small particles that spread out in a cone pattern from the rear of the armoured plate, and the armour itself may create spalling. Both are capable of causing harm to the crew inside the vehicle. However, one round alone is unlikely to defeat the vehicle or crew, as the cone of spalling and bullet fragmentation can be relatively small. The second effect is the incendiary tip of the projectile – mostly spent on the surface of the armour, with some limited behind-armour spread. The KPVT’s rate of fire – 600rpm - is the third and final mechanism. With the ability to fire ten rounds per second, the KPVT succeeds by penetrating a vehicle multiple times in a short period. However, there are a few confounding factors with the KPVT’s behind-armour effects. Titanium armour, for instance, Even well-armoured tanks such as the T-90 shown here can be defeated if behind-armour effects are not addressed or considered in the vehicle’s design. (Photo: armyinform.com.ua via Wikimedia Commons)
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