Armour-piercing projectile

Abstract: The invention relates to an armour-piercing projectile of the type which comprises a nose cone (1) with a rein­ forced tip (2) for mechanical penetration of reactive armour and an impact contact member (5), placed in the nose cone, for triggering the actuation part of the projectile upon impact against a target. The casing of the nose cone has a weak point (12) where the casing is designed to be deformed and make electrical contact with the contact member (5) upon impact of the projectile against a target. In order to prevent undesired particles in the form of metal shavings or the like from coming in between the casing and the inner shell of the contact member, a sealing ring (14) is inserted between the casing and the inner shell (5) at the rear part of the nose cone. This reduces the risk of unintentional contact function caused by such shavings or flakes situated between the shells in those parts where the contact distance is small.

Description: The present invention relates to an armour-piercing projectile of the type which comprises a nose cone with a reinforced tip for mechanical penetration of reactive armour and an impact contact member, placed in the nose cone, for triggering the actuation part of the projectile upon impact against a target, the impact contact member consisting of a full-calibre double shell in which the casing of the projectile constitutes an outer shell and the inner shell consists of a separate contact cone. For combatting of armoured vehicles, in particular tanks, it is previously known to use various types of antitank weaponry. Such weaponry is designed to penetrate even thick armour plate. Armour-piercing projectiles constitute a special type of antitank weaponry which is provided with a shaped charge, SC. A shaped charge comprises, in principle, an outer casing, a metal cone and an explosive. When the explosive detonates, the metal cone is flattened and a metal jet is formed which, with great force, penetrates even very thick and hard armour. As a result of their good action on armoured targets, shaped charges have for a long time constituted a serious threat to armoured vehicles. The developments which have taken place on the defence side involving the introduction of composite armour, reactive armour etc. have created a requirement for actuation parts with a high penetration capability even against these types of armour. Thus, armoured targets can be provided with a reactive armour of the mounted type positioned immediately in front of or at a distance from the main armour of the target. Such reactive armour can consist of two metal plates with an intermediate layer of explosive. Such reactive armour normally impedes the shaped charge jet of a projectile, and its penetration capability is drastically reduced. US Patent 4,831,936 previously discloses an armour-piercing projectile in which increased penetration capability with respect to active armour was created by means of the nose cone of the projectile being given such a design that it is able to mechanically penetrate the reactive armour before the shaped charge is initiated. This means that the penetration jet of the shaped charge can pass unimpeded by the reactive armour, and in this way full pene-tration capability in the main target is achieved. The front part or cap of the nose cone of the projectile has a reinforced tip for mechanical penetration of the reactive armour, and the impact contact member is positioned in the nose cone in such a way that contact is obtained only when the reinforced tip has passed the reactive armour without the latter detonating. According to one embodiment the cap has a rearward narrowing wall thickness. In the embodiment which is shown in the said patent, the tip of the nose cone is solid and more pointed than in conventional armour-piercing projectiles, and the impact contact member is not brought right to the tip of the projectile. This provides for the delay which is required for the projectile to be able to penetrate the reactive armour before the shaped charge is initiated. US patent 4,913,057, on which disclosure the preamble of independent claim 1 is based, previously discloses an armour-piercing projectile in which the front part of the nose cone is provided with an internal shoulder, and in which the front part of the contact member is situated close behind this shoulder. A good contact function is in this way retained even in the case of right-angle hits against a target. The front part of the contact member strikes the shoulder and closes the projectile's ignition system for triggering the shaped charge. Armour-piercing projectiles of the abovementioned type generally afford a very good function both in the case of typical inclined impact angles and in the case of right-angle impacts. However, with certain types of targets, the contact function may be impaired or completely fail even in these armour-piercing projectiles. Upon impact against a relatively thin-walled target, it can happen that the tip of the projectile penetrates even the wall of the target without contact being achieved between the contact member and the shoulder. In this case the casing is not deformed sufficiently to provide the necessary contact between the casing and the contact member in the form of an internal contact cone situated inside the casing. Moreover, at very low impact angles (30°), it can happen that the tip of the projectile is deflected without contact being made between the internal contact cone and the projectile casing. The aim of the present invention is therefore to provide an armour-piercing projectile which retains a good and reliable contact function even against relatively soft targets, for example targets in which the main armour of the target is relatively thin-walled, such that it is unable to stop the tip of the projectile from penetrating through the armour plate. The invention is characterized in that the casing of the nose cone has a weak point where the casing is designed to be deformed and make electrical contact with the contact member upon impact of the projectile against a target, and that the inner shell in association with the said thin-walled section has a bulge for the purpose of reduced contact distance between the two shells in the said section. In an advantageous embodiment, a sealing ring is inserted between the outer casing and the inner shell of the contact member at the rear part of the nose cone. This prevents shavings and other undesired particles from coming in between the two shells, the outer casing and inner shell, in the impact contact member and, particularly in the areas with a small contact distance, from causing unintentional contact between the shells. The invention will be described in greater detail below with reference to the attached drawings in which Figure 1 shows a first variant of the invention with a solid, pointed tip, and Figure 2 shows a second variant with a solid, truncated tip. Figure 1 shows the front part of an armour-piercing projectile provided with a nose cone 1 with a reinforced tip 2. The nose cone is screwed onto the projectile body 3 by means of a thread cutting 4. Alternatively, the nose cone can comprise two parts, a rear part which is screwed onto the projectile body, and a front tip hood. In conformity with an armour-piercing projectile which is shown in the previously mentioned US Patent 4,831,936, the tip is optimized so as to be able to pass the reactive armour without the latter detonating. The tip is thus solid and has a markedly small tip radius, and its material thickness in the longitudinal direction amounts to at least 4 to 5 times the wall thickness of the rear part of the nose cone. The tip 2' of the projectile which is shown in Figure 2 is also solid, but is truncated compared to the pointed tip which is shown in Figure 1. In some cases a truncated tip can increase the penetration capability of the projectile, since the tip is not deflected as easily against an inclined target surface. In other respects the two nose cones do not differ. In conformity with the previously known armour-piercing projectile, the nose cone also comprises an impact contact member in the form of a full-calibre double shell, a shell incorporated in the outer casing of the projectile and an inner shell 5. The outer and inner shells of the unused projectile are arranged at a distance and are insulated from each other in such a way that, upon impact of the projectile against a target, they can come into cooperation and make electrical contact with each other. The shells form a passive make contact in the projectile's ignition system for triggering the shaped charge. The nose cone comprises a rear, large space 6 in which the contact member is accommodated, and a front, shorter space 7 with increased material thickness in the walls. The transition between the relatively thin-walled rear part 6 of the nose cone and the front part 7 is designed as an internal shoulder 8 with an annular surface 9 situated in a plane at right angles to the longitudinal axis 10 of the projectile. The front cylindrical part 11 of the contact member is situated immediately behind the shoulder 8 and is insulated from this, and yet is designed in such a way that, upon impact of the projectile against a target, it can come into cooperation with the annular surface and make electrical contact with the outer shell. In contrast to the armour-piercing projectile which is shown in US Patent 4,913,057, the outer casing of the nose cone has a weak point or breakpoint in the form of a thin-walled section 12. In association with this section, the inner shell 5 has a bulge 13 for reducing the contact distance between the outer casing and the inner shell in this area. Upon impact of the projectile against a relatively "soft" target of the type in which the tip of the projectile penetrates part of the target, the thin-walled section 12 is deformed as a result of the compressive load, "squeezing", to which the nose area is subjected during penetration. In this way the outer shell comes into cooperation with the inner shell 5 of the contact member and provides the necessary contact function for triggering of the shaped charge part. Even in the case of small impact angles against hard targets, the thin-walled section 12 is deformed and contact is achieved in connection with the nose cone being broken or cracked in the weakened area. As has been mentioned above, it has previously been possible for the contact function to fail in the case of certain types of targets. In accordance with the invention, a breakpoint is defined in which a deformation occurs and provides the desired contact function even in such "hard" target types. Upon impact against hard targets and at typical impact angles, a normal contact function is achieved between the internal shoulder and the inner shell as previously. In this case the thin-walled section 12 is formed by an inner, annular recess in the outer casing. The wall thickness is not quite half of the wall thickness elsewhere. The section is situated approximately in the centre of the nose cone in the longitudinal direction and extends in the longitudinal direction to permit a bulge 13 on the inner contact cone. In order to prevent particles from penetrating between the outer and inner shells in the contact member and from causing unintentional contact function, a sealing ring 14 is inserted between the outer shell and the inner shell 5 at the rear part of the nose cone. Such particles can be, for example, metal shavings which can be worn loose from the thread 4 when the nose cone is screwed onto the projectile body. Such shavings could come loose and swirl around between the shells and bring about contact in those areas of the contact member where the contact distance is small. Particularly in the design according to the invention where the inner shell comprises an extra bulge 13, it is important to prevent particles, flakes etc. from coming in between the shells. The sealing ring 14 is therefore situated at the rear part of the nose cone in an area where the contact distance is greater. The sealing ring is made of an electrically non-conducting material, preferably compressible and insensitive to humidity, for example material marketed under the name Fagerdala PC 225. This material is very light and compressible and can be pressed in between the shells and sits secured in this position. The invention is not limited to the embodiment shown by way of example, but can be varied within the scope of the following patent claims.

Claims: Armour-piercing projectile comprising a nose cone (1) with a reinforced tip (2) for mechanical penetration of reactive armour and an impact contact member (5), placed in the nose cone, for triggering the actuation part of the projectile upon impact against a target, the impact contact member consisting of a full-calibre double shell in which the casing of the projectile constitutes an outer shell and the inner shell consists of a separate contact cone (5), characterized in that the casing of the nose cone has a weak point in the shape of a thin-walled section (12), which section is designed to be deformed and to provide electrical contact with the contact cone (5) when the projectile impacts against a target, and that the inner shell in association with the said thin-walled section (12) has a bulge (13) for the purpose of reduced contact distance between the two shells in the said section. Projectile according to claim 1, characterized in that a sealing ring (14) is inserted between the projectile casing and the inner shell (5) of the contact member at the rear part of the nose cone for the purpose of preventing particles in the form of shavings or the like from coming in between the two shells and from causing unintentional contact function. Projectile according to claim 2, characterized in that the sealing ring (14) is made of a light, compressible material, so that the ring can be pressed in between the two contact shells and sits secured in this position.

Inventors: GUSTAFSSON HANS, KARSBERG LARS, KROPP HANS-ERIK, GUSTAFSSON, HANS, KARSBERG, LARS, KROPP, HANS-ERIK
Applicants: BOFORS AB
Application year: 1990
Main classification: F42B12
IPC codes: F42C19