GB2207985A - Sabot projectile - Google Patents

Abstract

In an ammunition round of the type in which a projectile (1) is enclosed by a sabot (6) which is designed to disintegrate after firing of the round, the sabot (6) has bores (7) therethrough such that pressure generated therein during firing causes an increase in radial pressure between the sabot (6) and a barrel from which the round is being fired. <IMAGE>

Description

IMPROVED ROUND This invention relates to an ammunition round of the type in which a relatively small diameter dense core projectile is encased by a less dense outer casing known as a sabot, which separates from the core as the round leaves the gun barrel from which it has been fired.

Particularly in the field of armour piercing ammunition, modern projectiles are designed to be long and thin to be increasingly potent. A sabot is used to increase the cross-sectional-area of each round in the barrel to enable it to be fired from larger calibre gun barrels than would be required by the projectile part of the round alone to enable greater ranges to be attained. Separation of the sabot from the projectile is usually effected by the disintegration or discarding of the sabot, which is usually formed from a much less dense material than the projectile.

During firing of a round there is a tendency for the projectile to move relative to the sabot, due to their differing inertias and to uneven distribution of propellant forces on the ends thereof. In order to prevent this it is usual, in a round having a disintegrating sabot, for the projectile and sabot to be inter-engaged by, for example, a screw thread or a rib and channel connection. The resultant protuberances on the projectile can result in undesirable turbulence during flight of the projectile. Due to the hardness of material used in the projectile and the precision engineering needed to produce the ribs or threads (especially so for small callibre rounds) they are costly to produce.

According to the present invention an ammunition round includes a projectile circumferentially enclosed by a sabot, the sabot bring designed to disintegrate after projection of the round from a barrel, the sabot having at least one bore extending substantially along the along the length thereof adjacent an interface between the projectile and the sabot and being formed of a material such that when subjected to pressures as experienced during projection a radial pressure is induced at the interface.

Preferably the central axis of the said bore holes should lie on an increasing radius from the longitudinal axis of the core projectile as the holes run from the rear of the sabot towards the front. This feature provides additional radial pressure from the sabot onto the projectile to improve frictional retention.

Additionally, the sabot may be formed from two or more longitudinal segments. This allows the sabot to be discarded more effectively upon projection from the end of the barrel.

To further improve the inter-engagement of the sabot and the projectile,the diameter of the projectile may be increased towards the front of the core.

An embodiment of the invention will now be described by way of example only, and with reference to the accompanying drawings.

Figure 1 is a sectional side view of the sabot mounted on the projectile.

Figure 2 is a sectional from view along the line g-B on Figure 1.

Referring to Figure 1, the round consists of a substantially cylindrical dense projectile coaxially mounted inside a less dense sabot.

The projectile (1) has a pointed front end (2) followed by a conical section (3) followed by a slightly tapering middle section (4) of reducing diameter, to a main cylindrical section (5). The tapering of the middle section (4) is no more than 2 degrees.

The sabot (6) comprises a cylinder having an internal through bore, along the longitudinal axis of the sabot, of the same diameter as the main section (5) of the core (1). The sabot is made from high strength low density material such as Aluminium. As can be seen from Figure 2 the sabot (6) is provided with bore holes (7) running from the rear of the sabot towards, but not reaching, its front end. These holes (7) do not run parallel to the core (1) by diverge from it as they progress from rear to front of the sabot. More holes (7) may be provided. The holes (7) may be round or may have a cross section (8) as shown in Figure 2.

Towards the rear of the sabot (6), a shallow groove (12) runs around the circumference of the sabot (6). A driving band (10) made of a plastic material is.inset in the groove (12). The thickness of the band (10) is greater than the depth of the groove (12). This band retains the segments of the sabot together around the projectile and acts as a seal for the combustion gas and is destroyed as the round leaves the barrel. A cartridge case (not shown) is slid over the rear end of the sabot up to the driving band (10). Towards the front end and placed around the circumference of the sabot (6) is a centering band (11). This stabilises the round in the barrel and is also destroyed upon firing.

The sabot is made from a single moulding with fracture grooves (13) running from the front towards the rear but leaving a solid portion (14) at the rear of the sabot. Alternatively, the sabot may be made from separate longitudinal segments retained together by a collar which fractures upon firing. The sabot, either single moulding or segmented , may be provided with a nose cone (15).

In operation, the combustion gases shoot into the bore holes (7) providing a pressure on the walls of the holes. The holes are located sufficiently close to surface of the sabot interfacing with the projectile to permit the interface to deform under pressure, thus transferring the combustion pressures of firing onto the central projectile, and providing a frictional retention force between the two.

Clearly, the bore holes must be sufficiently distant from the outer surface of the sabot since any radially outward deformation would cause the sabot to expand in the barrel.

If the central axis of each bore hole lies on an increasing radius from the longitudinal axis of the encased projectile as the holes run from the rear of the sabot towards the front, and throughout their length the holes are still located sufficiently close to the sabot/ projectile interface, a greater frictional force is effected upon the projectile.

The shape of the bore hole section will further determine the extent of deformation of the sabot at the sabot/projectile interface, and the section shown in figure 2 is preferred to a circular crosssection.

Although the invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made without departing from the scope of the invention as defined in the appended claims.

Claims (8)

1. An ammunition round having a projectile circumferentially enclosed by a sabot, the sabot being design ed to disintegrate after projection of the round from a barrel, the sabot having at least one bore extending substantially along the length thereof adjacent an interface between the projectile and the sabot and being formed of a material such that when subjected to pressures as experienced during projection a radial pressure is induced at the interface.

2. An ammunition round, as claimed in Claim 1 in which the central axis of the bore holes lies on an increasing radius from the longitudinal axis of the core as the holes run from the rear of the sabot towards the front.

3. An ammunition round, as claimed in Claim 2 in which the diameter of the dense core increases towards the front of the core.

4. An ammunition round, as claimed in Claim 3, in which the sabot is provided with one or more circumferential seals.

5. An ammunition round, as claimed in Claim 4 in which the sabot is formed from two or more separate arcuate segments extending longitudinally.

6. An ammunition round as claimed in Claim 5 in which the sabot is a one piece component having a plurality of longitudinal fracture grooves.

7. An ammunition round has claimed in Claims 5 or 6 in which the sabot is provided with a nose cone.

8. An ammunition round substantially as hereinbefore described with reference to the accompanying drawings.