Shell with multi-charges

Abstract: This invention concerns a device, such as a shell [1] or the like, with at least a first charge unit and a second charge unit [2], [6] arranged in series one after the other. The charge units include one RSV charge [3], [7] each. The charges are designed to be detonated one after the other with a time separation between the detonations. In order to suppress the interference to an undetonated charge by a shock wave generated by the detonation of a previously detonated charge, the joint [12] that connects the charge units [2], [6] has been designed in a special way. According to the invention the joint includes a sprung damping section [13], parallel to the longitudinal axis of the device, that mechanically fastens together the two charge units. In addition a rigid support device [22] is connected to the damping section [13] and dimensioned so that when the damping section is in an unstressed state there is a clearance [23] in the longitudinal axis of the device between the two charge units [2], [6].

Description: This invention concerns a device, such as a shell or the like, containing at least a first charge unit and a second charge unit arranged in series one after the other and connected to each other by means of a joint. These charge units contain one RSV charge each and are designed to be detonated one after the other with a time separation between the detonations. The joint comprises a damping section that mechanically fastens together the two charge units and has a damping ability in the longitudinal direction of the device. The number of RSV charges contained in a shell can be two or more. Versions with two RSV charges are called tandem RSV charges, while versions with three RSV charges are called triple RSV charges. A collective name for versions with more than one RSV charge is multi RSV charges. A shell in accordance with the first paragraph is already known by, for example, DE patent specification 37 40 412. In this document a tandem RSV design is described proposing a solution to the undesirable effect that a detonating charge can have upon undetonated charges. According to the solution one or more damping elements are arranged in series between the charges. However, the joint between the charges must have a certain degree of rigidity to stand the forces during, for example, the launching stage of the device, for example, when the device accelerates in a barrel. A deformation in the last mentioned stage is a catastrophe for the operation of the device. One problem concerning the design of RSV charges that are to detonate at different times is, as already mentioned, the effect that a detonation charge has upon the undetonated charges. Normally the structure that lies between the charges is designed to be so strong that it can support the mass in front of it during the launching stage. Designs with such a strong structure have, however, the disadvantage that they act as excellent shock wave transmitters. A shock wave generated by the detonation of a first charge is therefore transmitted almost undamped to subsequent charges. This in turn cause interference to the RSV beams received by a subsequent charge or even cause its ignition system to be damaged. The aim of this invention is to make a device such as a shell or the like that does not exhibit the problem described above with interference caused by a shock wave generated by a previous detonation and which is not adversely deformed before the ignition of the charge or charges. The aim of the invention is achieved by means of a device in accordance with the first paragraph of the introduction to the description, characterised in that a rigid support device is provided in connection to the outer surface of the damping section, the support device being dimensioned so that when the damping section is in an unstressed state there is a clearance in a direction parallel to the longitudinal axis between the support device and at least one of the two charge units. The invention thus achieves a simple way of attenuating the shock waves that cause interference by means of the interaction between a damping section and a support device that falls away after the launching stage. According to an advantageous version the device is characterised in that a spring device is designed to operate between the damping section and the support device. In this way it is ensured that the support device separates from the damping section in a simple and reliable way after the launching stage. The spring device can consist of plate springs. According to another advantageous version the support device consists of a number of separate support elements positioned around the damping section. The support elements can thereby be designed as longitudinal casing sections. The support elements give the structure the requisite strength during the launching stage, are simple to manufacture and can be easily separated after the launching stage. According to a version that is reliable and easy to assemble, the damping section is connected to the charge units by threaded connectors. In order to create a good interaction between the support device and the charge units, according to a further version the rear part of a front charge unit and the front part of a rear charge unit which are connected by means of a damping section are provided with contact surfaces for interaction with the support device. This invention will be described in greater detail by means of one version as an example with reference to the attached drawings, where Figure 1 shows a shell according to the invention with tandem RSV charges, and Figure 2 shows in greater detail the joint between the charge units in which the RSV charges are contained. The shell [1] in Figure 1 contains a first charge unit [2] containing an RSV charge [3] with liner [4]. In the rear part of the charge unit there is an SA unit (Safety Ammunition Unit) that among other things provides safety and arming functions. The shell also contains a second charge unit [6] containing an RSV charge [7] with liner [8] and an SA unit [9]. At the very rear of the shell there is a rocket motor [10] for launching the shell and a collapsible fin assembly [11]. The charge units are connected by a joint [12]. The joint [12] is shown in greater detail in Figure 2. A sprung damping section [13], preferably made of a plastic material, joins together the rear part [14] of the first, front charge unit [2] and the front part [15] of the second, rear charge unit [6]. The damping section [13] is connected to the charge units via threaded connectors [16], [17] and [18]. In the version shown, a casing [19] with internal and external threads provides the connection to the second charge unit [6]. The rear part [14] of the first charge unit is provided with a contact surface [20]. In a corresponding way the casing [19] is provided with a front contact surface [21]. Between the contact surfaces [20] and [21] there is a rigid support device [22]. The support device can consist of several separate support elements constructed as longitudinal casing sections. In the unstressed state depicted there is a clearance [23] for the support device between the two contact surfaces [20], [21]. Between the damping section [13] and the support device [22] there is a space [25] that contains a spring device [24]. During the activation stages of the shell [1] the joint [12] works as follows. When the shell is subjected to the launch acceleration, the damping section [13] is compressed longitudinally. The clearance [23] disappears and the rigid support device [22] comes into direct contact with the contact surfaces [20], [21]. This means that a rigid construction is achieved that is able to support the mass in front of it. Later when the launch acceleration ceases, which normally occurs only after the shell has left the barrel, the damping section [13] springs out again. This means that the clearance [23] reappears and the support device is no longer held fast between the contact surfaces [20], [21]. The support device [22] can now be separated from the shell [1] by the action of the spring device [24]. Thereby the connection between the charge units [2], [6] has been made as weak as possible for the requirements that are made of the connection for holding the shell together during the transportation of the shell at the airfield. Normally no great strength is required for this holding-together function. The weakened connection between the charge units following the launch means that only a very small part of the shock wave from a detonation is transmitted to a charge that is to detonate at a later time. Dynamic and static tests have been carried out that confirm the above. This invention is in no way limited to the version described in the example, but can contain a number of modifications within the framework of the invention as defined by the patent claims. For example, it could be possible to have versions with more than two RSV charges. In addition the design of the support device and the spring device can be modified. Instead of threaded connections the charge units can, for example, be glued or moulded together.

Claims: Device, such as a shell (1) or the like including at least a first charge unit (2) and a second charge unit (6) arranged in series one after the other along a longitudinal axis of the device and connected to each other by means of a joint (12), which charge units (2,6) include one RSV charge (3 resp. 7) each and are designed to be detonated one after the other with a time separation between the detonations, the joint (12) comprising a damping section (13) that mechanically fastens together the two charge units (2,6) and has a damping ability in the longitudinal direction of the device, characterised in that a rigid support device (22) is provided in connection to the outer surface of the damping section (13), the support device (22) being dimensioned so that when the damping section (13) is in an unstressed state there is a clearance (23) in a direction parallel to the longitudinal axis between the support device (22) and at least one of the two charge units (2 resp.6). Device according to Patent Claim 1, characterised in that a spring device (24) is designed to operate between the damping section (13) and the support device (22). Device according to Patent Claim 2, characterised in that the spring device (24) consists of plate springs. Device according to any of the above Patent Claims, characterised in that the support device (22) consists of a number of separate support elements positioned around the damping section (13). Device according to Patent Claim 4, characterised in that the support elements are designed as longitudinal casing sections. Device according to any of the above Patent Claims, characterised in that the damping section (13) is connected to the charge units (2,6) by threaded connectors. Device according to any of the above Patent Claims, characterised in that the rear part of a front charge unit (2) and the front part of a rear charge unit (6), which are connected by a damping section, are provided with contact surfaces (20,21) for interaction with the support device (22).

Inventors: HELANDER JYRKI, HELANDER, JYRKI
Applicants: SAAB AB
Application year: 1998
Main classification: F42B12
IPC codes: F42B12