Base bleed bullet

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Base bleed bullet. Above view of the floor of the projectile with the outlet nozzles, below section through the rear part of the projectile with the pyrotechnic gas generator

The base bleed projectile is a special, extended range type of artillery projectile . It achieves the increase in range by reducing the floor suction of the projectile.

background

The range of an artillery shell depends on various factors. It is primarily influenced by the muzzle velocity of the projectile, which in turn depends on the strength of the propellant charge and the length of the barrel, and the air resistance of the projectile during flight. Therefore, the rule is that a higher muzzle velocity and lower air resistance increase the range.

Since changes to the design of the gun are usually necessary to increase the muzzle velocity, attempts are made to increase the range over the ammunition in order to reduce the effort. This led to the development of extended range ammunition . The existing, conventional ammunition can still be used to fight closer targets.

Influencing types of air resistance

There are essentially three types of air resistance that act on a projectile during flight:

  • The impedance has in conventional artillery shells a proportion of about 50 to 60 percent of the total resistance.
  • The frictional resistance contributes between 7 and 11 percent of the total resistance.
  • The soil suction has a share of 30 to 40 percent. It arises from the fact that vortices are created behind the projectile due to the rapid flight, which create a negative pressure. The projectile is braked by this suction.

The base bleed bullet

Base bleed projectiles have a pyrotechnic charge in the rear that is ignited when they are launched. Its task is to reduce the negative pressure behind the projectile by emitting combustion gases and thus to reduce the suction. If the pyrotechnic set is enlarged further, there is a smooth transition to the projectile with an additional rocket drive .

Base bleed projectiles enable a range increase of around 20 to 30 percent, depending on the design. With a typical NATO gun, for example, the range increases from around 23 to around 28.5 km. With the Panzerhaubitze 2000 the range could even be increased by around 40 percent to 56 km with a combined system of base bleed and rocket set.

However, the space and weight requirements for the pyrotechnic charge reduce the payload of the projectile. A bullet of the NATO standard caliber 155 mm in the conventional version can carry 88 bomblets , but with base bleed only 64. With the caliber 203 mm, the number is reduced from 180 to 135. This corresponds to a reduction of around 25 in both cases Percent.

Individual evidence

  1. ↑ KMWeg press release on increasing reach ( memento from September 27, 2007 in the Internet Archive )

literature

  • Raimund Germershausen : pipe artillery systems. In: Modern Artillery Systems. Forum of the German Society for Defense Technology at the Artillery School in Idar-Oberstein on the 6th and 7th. October 7, 1983. Bernard & Graefe Verlag, Koblenz 1985, ISBN 3-7637-5603-5 , pp. 25-36 ( Wehr und Wirtschaft 3).