National defence is fundamental to the security of any country. To keep its citizens safe and run a stable government countries pay utmost attention to their defense system. They purchase / manufacture high-tech weapons, maintain a skillful army and strengthen their intelligence system so that its citizens can stay safe and protected at their homes. Scientists, engineers, and other technocrats ponder over ways as to how to construct the best devices for a strong defence system. Two main features of a weapon used in war are the accuracy of the firing, and the impact it has on the opponent side.
Professor G. Rajesh, and M. R. Sreelal have recently published a paper on how the accuracy and the impact of an Armour Piercing Fin Stabilized Projectiles (APFSDS), the primary ammunition used for ‘Main Battle Tanks (MBT)’, can be made more effective by changing the configuration of the sabot, a primary component of the Kinetic Energy Projectile system. This helps the projectile to be launched with minimal disturbances during the launching phase.
These ammunitions use its enormous amount of kinetic energy to penetrate and destroy the armour of the MBTs that is based on an APFSDS system consisting of a projectile, which is stabilized by fins, multi-segmented sabots, and an obturator.
In such a system, the segmented sabots transfer the momentum of the hot combustible gases to the projectile through the buttress grooves provided on them. Once the projectile is launched from the holds of the sabot, the sabot has no further use and is discarded. However, the sabot is essential at that stage because it holds and guides the projectile through the gun barrel.
There are generally two problems with the conventional sabot design; the mechanical interaction (contact) between the sabot and the projectile as it is launched, which could reduce the accuracy of the launch of the projectile, also known as ‘Target Impact Dispersion (TID)’, and the very high drag configuration of the conventional sabot leading to reduction of the projectile muzzle velocity, which is usually not tackled with. An ideal sabot should have less weight and separate from the projectile without disturbing its trajectory.
In this paper, it is proposed to move the centre of the aerodynamic lifting pressure closer to the centre of gravity of the sabot thereby reducing the rotation of the sabot and mechanical interaction between sabot and projectile at the rear end. Two new designs proposed here consist of an I-section bore rider, unlike conventional sabots. In one of them, there isa cavity beneath the obturator, and is lighter in mass and has a less transverse moment of inertia. This design helps the sabot to separate more easily from the projectile. Besides that the symmetrical shape of the cavity beneath the obturator also helps to produce extra lift force during the initial stages of the launch of the projectile.
It is concluded from the analytical study that the new lift separation sabot performed better when compared to the conventional sabot. There was less mechanical interaction and more accuracy in the launch of the projectile. This new design of the armour piercing projectile device could be a useful addition in the vital artillery force of our nation’s defence, considering the fact that the Kinetic Projectiles are extremely difficult to be defeated.
Article by Akshay Anantharaman