EP1715287B1

EP1715287B1 - Warhead and projectile or missile comprising such a warhead

Info

Publication number: EP1715287B1
Application number: EP05445022A
Authority: EP
Inventors: Thomas Widlund
Original assignee: Saab AB
Current assignee: Saab AB
Priority date: 2005-04-19
Filing date: 2005-04-19
Publication date: 2011-12-21
Anticipated expiration: 2025-04-19
Also published as: ES2375713T3; ATE538357T1; EP1715287A1; ES2375713T8

Abstract

The present invention relates to a warhead (2) comprising a charge unit (5) with an explosive charge (7), a liner (8) and an initiator (9), the warhead having a fragmentation capacity. The invention also refers to a projectile or a missile comprising such a warhead (2). According to the invention a stopper (6) is provided in front of the charge unit (5) to interfere with the liner (8) of the charge unit at such a distance from the charge unit (5) that the essential part of the acceleration of the liner (8) under influences from explosive gases of the explosive charge has taken place before reaching the stopper (6). This creates a splinter mode with fragments spread in desired directions of space.

Description

The present invention relates to a warhead comprising a charge unit with an explosive charge, a liner, an initiator and a stopper provided in front of the charge unit to interfere with the liner of the charge unit, the providing of the stopper creating a splinter mode of operation of the warhead. The invention also refers to a projectile or missile comprising such a warhead.
In connection to warheads the charge unit may be constituted by a shaped charge or a charge unit explosively forming a projectile (EFP).
A warhead according to the first paragraph based upon the shaped charge principle is previously known from DE 11 28 345 B , wherein a warhead according to the preamble of claim 1 is disclosed. In this kind of warhead a charge jet is generated. Such a jet is intended to generate small but deep holes in armour targets. By introducing a stopper the penetration ability is decreased and there is a material accumulation with a certain velocity forwards. This results in a wider effect, wider hole, at the target surface. However, no real splinter mode with fragments is obtained.
In another warhead previously known from Swedish patent 0002490-1 , a fragmentation capacity is identified. According to the embodiment described with reference to Figure 5 the warhead is provided with a splinter shell comprising heavy metal bullets. In the space between the splinter shell and the liner an additional explosive charge adapted to the available space is inserted. The fragmentation capacity is mainly due to the additional explosive charge and splinter shell inserted. Creating fragmentation capacity requires several additional rather complex and bulky components to be housed within the warhead.
According to our invention there is no need for an additional explosive charge or a splinter shell. The creation of the fragmentation capacity is obtained by using the liner of the comprised charge unit. By providing a stopper in front of the charge unit interfering with the liner a splinter mode is created spreading fragments. The features essentially characterizing the warhead is that the charge unit is embodied to explosively form a projectile and that the stopper is located at such a distance from the charge unit that the essential part of the acceleration of the liner under influences from explosive gases of the explosive charge has taken place before reaching the stopper creating a splinter mode with fragments spread in desired directions of space.
In this connection it could be noted that a stopper is previously known from the above cited Swedish patent, see the embodiment described with reference to Figure 4. However, this stopper is located much closer to the liner and the object of the stopper is to stop the liner before it has accelerated preventing a shaped charge jet or projectile to be developed so that accidental ignition is prevented.
According to US patent 5 337 673 a warhead is previously known in which the liner is designed to produce fragmentation by embedding an expanded metal liner on the interior surface of a casing for a warhead. This patent proposes another way of producing fragmentation and which is not based upon acceleration of the liner before collision with the stopper.
Another way of creating fragmentation capacity and supposed to be known without any reference available is to use several initiation points within the explosive charge. This is considered an expensive and complicated method not expected to result in particular advantageous fragmentation.
A favourable embodiment of the invention is characterized in that the stopper is exchangeable for different stopper embodiments. By the fact that the stopper is exchangeable the warhead can be adapted for different requirements of fragmentation structures and spreading by change of stopper. By leaving out the stopper a complete standard charge unit effect is obtained. Another way of adapting the warhead to different requirements is to provide the stopper in front of the charge unit such that it can be folded-away to give free way for a projectile.
For suitable dimensions of the stopper it is proposed by another preferred embodiment to provide the stopper at a distance in front of the charge unit that exceeds the length of the stopper. The embodiment admits the liner to be adequately accelerated before it reaches the stopper resulting in an advantageous fragmentation. Other preferred dimensioning of the warhead proposed are that the length of the stopper lies within 0.5 to 5 times the diameter of the warhead and preferably within 0.5 to 1 times the diameter and that the stopper is provided a distance in front of the liner of the charge unit that essentially corresponds to a travelling time of the liner within a time interval of 30 - 150 µs and preferably 50 - 60 µs.
Preferably the diameter of the stopper is less than half the diameter of the charge unit. Such a dimensioning has turned out to result in adequate fragmentation and spreading.
Furthermore the stopper preferably has a rotational symmetrical shape. This i. a. makes it easier to obtain a balanced embodiment when introducing the stopper into a projectile or missile.
The stopper may assume many different shapes. According to a first advantageous shape the stopper is shaped as a circular cylinder. According to a second advantageous shape the stopper is shaped as a rotation symmetrical body having a first section with a first diameter and a second section with a second diameter different from the first diameter. According to a third advantageous shape the stopper is shaped as a frustum of a cone. According to a fourth advantageous shape the stopper is funnel shaped having its tip directed towards the charge unit. According to a fifth advantageous shape the stopper is shaped essentially as a spherical body.
Advantageous materials to be used for the stopper are i. a. steel and heavy metals such as tungsten.
The warhead has a charge unit embodied to explosively form a projectile.
Interferences between such charge units and stoppers to create fragmentation are easy to arrange for within the envelope of a projectile or missile and it has turned out that such a charge unit in cooperation with the stopper results in an effective fragmentation generation.
The invention will now be described in more detail with reference to the accompanying drawings in which:

Figure 1 schematically shows a projectile according to the invention housing a warhead according to the invention.
Figure 2 schematically illustrates the interference between the liner of a charge unit and a stopper provided in the warhead according to the invention at six different points of time.
Figures 3a-3e schematically show five different embodiments of a stopper to be comprised in the warhead according to the invention.
Figure 4 schematically shows an embodiment of a carrier for a stopper.

The projectile shown in figure 1 comprises a warhead 2 within its envelope 3 and is provided with fins 4.1, 4.2. The warhead 2 includes a charge unit 5 and a stopper 6. The charge unit 5 is built up of an explosive charge 7, a liner 8 and an initiator 9. The stopper 6, see figure 4, is arranged in the centre of an annular element 10 having branches 11, 12, 13 connecting the periphery of the annular element with the stopper 6. The envelope 3 of the projectile is embodied to receive and keep the annular element 10 in position by some kind of conventional locking means and thus not show.
Dashed lines 23, 24 and 25 in figure 4 indicate how the stopper 6 can be divided into sections in case that the stopper 6 is to be folded away to create free space for a projectile. In such a case the stopper could be rotated around schematically indicated hinge elements 26, 27 and 28 of any suitable known construction.
The interference between the liner of the charge unit and the stopper will now be described with reference to figure 2.
At time point I the liner 8 has been accelerated to an optimal speed under influence from explosive gases deriving from the initiated explosive charge 7. At time point II the liner 8 has reached the stopper 6 and partly deformed the stopper at the end facing the liner 8. A little bit later at time point III the stopper has been further deformed. The length of the stopper now has been reduced to less than a third of the original length. At he next time point shown, time point IV, fragments 14, 15 are beginning to leave the liner 8 and stopper 6. This leaving or separation of fragments goes on further as illustrated at time points V and VI.
When locating the stopper in front of a charge unit, it is usually known how the liner accelerates from notes entered into the specification of the charge unit in question, so that the stopper is located sufficiently far away from the front of the charge unit.
Figure 3a-3e shows five different embodiments of the stopper 6 that have been found advantageous with respect to the fragmentation procedure.
According to figure 3a the stopper 6 consists of two circular cylinders 16, 17 having different diameters but a common symmetry axis 18. As indicated in figure 3a the circular cylinder having the shortest diameter is intended to be positioned closest to the charge unit 5. In figure 3b the circular cylinders have changed positions mutually.
According to figure 3c the stopper 6 has the shape of a frustum of a cone 19 turned such that the bottom 20 of the cone is facing the liner 8.
According to the embodiment of the stopper 6 shown in figure 3d, showing a cross section view through the centre of the stopper, the stopper 6 is funnel shaped having its tip 21 directed towards the charge unit.
Figure 3e shows an embodiment of the stopper having an essentially spherical shape 22.
Taken together it is realised that the shape of the stopper can vary within wide limits and that the particular shape is dependent on i. a. the kind of fragmentation and directions of spreading wanted. When looking for example at the simple shape of the circular cylinder of the stopper 6 of figure 1, it is realised that diameter and length can be varied.
Furthermore the material used for the stopper, such as steel and heavy metals, may be homogenous or non-homogenous in some way. It is also possible to mix different materials.

Claims

A warhead (2) comprising a charge unit (5) with an explosive charge (7), a liner (8), an initiator (9) and a stopper (6) provided in front of the charge unit (5) to interfere with the liner (8) of the charge unit (5), the providing of the stopper (6) creating a splinter mode of operation of the warhead (2), characterized in that the charge unit (5) is embodied to explosively form a projectile, EFP, and that the stopper (6) is located at a distance in front of the charge unit (5) that exceeds the length of the stopper (6), where said stopper (6) has a length within 0.5 to 5 times the diameter of the warhead (2), creating a splinter mode with fragments (14, 15) spread in desired directions of space.
A warhead as claimed in claim 1, characterized in that the length of the stopper (6) lies within 0.5 to 1 times the diameter of the warhead (2).
A warhead as claimed in any of the preceding claims, characterized in that the stopper (6) is exchangeable for different stopper embodiments.
A warhead as claimed in any of the preceding claims, characterized in that the stopper (6) is provided in front of the charge unit (5) such that it can be folded-away to give free way for a projectile.
A warhead as claimed in any of the preceding claims, characterized in that the diameter of the stopper (6) is less than half the diameter of the charge unit (5).
A warhead as claimed in any of the preceding claims, characterized in that the stopper (6) is provided a distance in front of the liner (8) of the charge unit (5) that essentially corresponds to a travelling time of the liner within a time interval of 30 - 150 µs and preferably 50 - 60 µs.
A warhead as claimed in any of the preceding claims 1-6, characterized in that the stopper (6) is rotation symmetrical.
A warhead as claimed in any of the preceding claims 1-7, characterized in that the stopper (6) is shaped as a circular cylinder.
A warhead as claimed in any of the preceding claims 1-7, characterized in that the stopper (6) is shaped as a rotation symmetrical body having a first section (16) with a first diameter and a second section (17) with a second diameter different from the first diameter.
A warhead as claimed in any of the preceding claims 1-7, characterized in that the stopper (6) is shaped as a frustum of a cone (19).
A warhead as claimed in any of the preceding claims 1-7, characterized in that the stopper (16) is funnel shaped having its tip (21) directed towards the charge unit (5).
A warhead as claimed in any of the preceding claims 1-7, characterized in that the stopper (6) is shaped essentially as a spherical body.
A warhead as claimed in any of the preceding claims, characterized in that the stopper (6) is made of steel.
A warhead as claimed in any of the preceding claims 1-12, characterized in that the stopper (6) is made of heavy metal.
A warhead as claimed in claim 14, characterized in that the stopper (6) is made of tungsten.
A projectile comprising a warhead as claimed in any of the preceding claims.
A missile comprising a warhead as claimed in any of the preceding claims 1-15.