Target ballistics

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The target ballistics (also: terminal ballistics or terminal ballistics ) describes as a subfield of ballistics the behavior of projectiles when striking a target, penetrating a target or when penetrating a target. Targets can be different types of bodies in the physical sense; both solid, liquid and gaseous bodies.

In the field of weapons research, soft targets are often simulated with materials such as ballistic gelatin or soap. If the target is a human or an animal body, the term wound ballistics is also used .

Soft targets

The target ballistic behavior of the Ogival bullets used in modern rifles depends on the shooting distance and the bullet construction.

Due to the twist of rifled barrels , the projectiles rotate around their longitudinal axis, which prevents them from tipping and overturning. Disturbances such as vortex formation in the airflow cause a certain deviation of the bullet's (rotational) axis from the flight path, so that the drag force of the air flown through does not act centrally, but next to the bullet's center of gravity. This tilting moment causes the projectile to precess as a top with its axis of rotation on a cone around the current direction of the flight path . This precession frequency is strongest shortly after the launch and decreases with the duration of the flight due to the air resistance which decreases with the flight speed. The fact that the precession angle can also decrease is a more complex damping process.

The precession determines the behavior when penetrating relatively soft media such as wood. In the case of high precession, as is to be expected at shorter shooting distances, a bullet with a low tendency to deform can overturn in the target medium, which is favored by the rear-heavy construction of modern long bullets. Due to the larger cross-section when rolling over, kinetic energy is transferred very quickly to the target medium. This reduces the penetration effect and, if necessary, enlarges the temporary wound cavity . Under certain circumstances, such bullets can break due to the high forces involved in rollover. At greater distances, when the precession of a projectile has decreased, the rifling can stabilize the projectile as it penetrates a soft target medium. This can mean that the penetration performance of a projectile initially increases as the firing distance increases. For example, the penetration depth of a .30-06 bullet in dry sand at a speed of 508 m / s is 33 cm compared to a penetration depth of 16 cm is 823 m / s.

The movement of deformation bullets can remain stable even at high speed due to the mushrooming after penetrating the target. Due to the large cross-section of the deformed bullet, the kinetic energy is quickly transferred to the target medium, which reduces the penetration effect.

Hard goals

In order for a projectile to penetrate a hard target purely by itself, i.e. only by kinetic energy and not with the help of explosives as is the case with shaped charge and squeeze-head ammunition, significantly different conditions are necessary than with soft targets. This is mainly due to the fact that many hard goals such as B. Tanks were specially developed against the typical projectiles for fighting soft targets.

In the case of massive hard targets, sufficient penetration force can only be achieved if the impacting projectile is able to overcome the flow limit of the target medium through the pressure on impact , without being too much deformed by the pressure itself. For this reason, armor-piercing solid bullets usually have a large mass, contain specifically dense and hard materials (e.g. tungsten ) and are fired at a significantly higher muzzle velocity than projectiles for soft targets.

See also

literature

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Individual evidence

  1. ↑ Eisnecker, Finze, Hocke, Skrobanek: Kammer-Diener, 120 years 8x57, visor, international weapons magazine, issue 12/2008, pp. 6-18
  2. ↑ David Harding (ed.), Waffen-Enzyklopädie, Motorbuch Verlag, ISBN = 3-613-01488-2, 2nd edition, 1995, p. 113
  3. ↑ a b X.W. Chen, YB He, G. Chen, M. Qu: STUDIES ON BUCKLING AND FAILURE OF PROJECTILES UNDER PERFORATION , 2007 (online PDF 403 KB) ( Memento from May 10, 2018 in the Internet Archive )