EP0144293B1

EP0144293B1 - A device for the mutual drawing away of the submunitions of spinless subammunition projectiles

Info

Publication number: EP0144293B1
Application number: EP84830249A
Authority: EP
Inventors: Rodolfo Andreetta
Original assignee: Simmel Difesa SpA
Current assignee: KNDS Ammo Italy SpA
Priority date: 1983-11-30
Filing date: 1984-09-10
Publication date: 1988-09-07
Also published as: ATE37085T1; ES538080A0; ES8700424A1; EP0144293A1; DE3473918D1; IT1167034B; IT8323946A0

Abstract

A device for the mutual drawing away of the submunitions of a subammunition spinless projectile (1) comprises at least one flat spring (4) for each layer of submunitions (2). This spring (4) is disposed under preloaded condition between the submunitions (2), in contact at least with some of them and is adapted to stretch out when the submunitions (2) are ejected from the projectile (1) and to draw mutually said submunitions (2). The device according to the invention makes it possible to substantially increase the coverage on the ground of an individual subammunition projectile (1).

Description

The present invention relates to spinless subammunition projectiles of the type of the mortar bombs or warheads, in which the submunitions are disposed in parallel layers, and more particularly to a device for the mutual drawing away of the submunitions once they have been ejected from the projectile in which they were contained.
It is known that, f.e., mortar shots are fired by smoothbore barrels which do not cause any spin effect. As a result, it is impossible to utilize centrifugal forces for separating parts, f.e. submunitions, intended to be mutually drawn away.
- The same applies to warheads for missiles.
It is also known that the simple ejection of the composite subammunition contents from the projectile does not permit per se the achievement of the desired effect on ground, i.e. the coverage of an ample ground area, if no mutual drawing away of the submunitions is carried out, inasmuch as in this case the centrifugal component which ejects radially such submunitions does not intervene.
In the earlier European Patent Application No. 83830263.6 (EP-A1-0117967 filed in the name of the same applicant, an arrangement is described for drawing away from one another the cylindrical segments, referred to as cheeks, of an instantaneous opening parachute containing device for mortar bombs of the illuminating type comprising a leaf spring disposed in a seat provided in the cheeks. The problem involved is different with respect to the present Application both for the nature of the charges to be driven away (cylindrical segments of a relatively small size and weight), and for the presence of the parachute which is packed inside the bomb.
At the present state of the art one relies on the randomness of the distribution of the submunitions, possibly assisted by the aerodynamic effects of the armament straps of the submunitions or other similar devices provided thereon.
DE-B-1 208 220 (Claim 1, lines 26 to 35) provides for submunitions in tubes (Abschuss- rohren 9) each of which is joined through a corrugated flexible section (10) to a center tube (2). Each tube can be spread out angularly with respect to the center tube (2) by a flat spring (12) whose action and reaction forces are applied respectively to the spreadable tubes (9) and the center tube (2). Thus, the preamble of claim 1 is based on DE-B-1 208 220.
FR-A-2 275 748 covers the mutual drawing away of reflecting material, and the characteristics of the drawing away system are suited to this particular contents of a multitude of lightweight elements. The element (11, fig. 3 and Claim 1) which causes the content to be drawn away when it is stretched out is defined as a "bande d'ejection" (Claim 1, line 9) represented, for example, by a wire (page 3, line 12), and it is not expected to be or to act as a spring. Its stretching out is not obtained by spring action but by its being pulled out of the projectile by the separation of the two parts (1 and 3) of the projectile to at least one of which the wire is attached.
In this mode of operation, the reaction forces are partly borne by the structure consisting of the wire and the projectile part to which it is attached and by which it is taut. The drawing away could also work if there were a single charge.
FR-A-2 196 456 provides a totally different charge spreading out system, a plurality of heads being secured at different heights to flexible bands 50 axially extended along the projectile and whose upper ends are secured to the upper part of the projectile. In their spread-out condition the heads remain fastened to the bands and to the projectile.
FR-A-2 101 786 provides . for springs 53 which in their constrained state are axially oriented and which are shown to be secured to a central structure by which the reaction forces are borne.
The abovementioned arrangements of the prior art are not normally sufficient to obtain a good distribution of the submunitions so as to cover an ample ground area, or they involve cumbersome, heavy and costly reaction structures which detract from the useful load of the projectile.
It is the object of the present invention to eliminate these serious disadvantages of the prior art by providing a device which makes it possible to mutually draw away radially the submunitions once the projectile is ejected and to obtain a good distribution of the submunitions and to cover a ground area which is notably ample with respect to the ground area covered by the submunition projectiles of the prior art with an improvement in space, weight, simplicity of manufacture, assembly and cost of the projectile.
More particularly, the device for drawing away the submunitions according to the invention is characterized in that it comprises at least one flat spring for each submunition layer, said spring being disposed under preloaded conditions among the submunitions of its respective layer, and being adapted to stretch out when the submunitions are ejected from the projectile thus mutually drawing away radially the submunitions from one another and further characterized in that the spring of each layer in its preloaded condition inside the projectile is oriented on a plane substantially perpendicular to the longitudinal axis of the projectile, that said spring is in contact, radially inwards, directly and only with submunitions of the layer, at least with two of them and, radially outwards, with the peripheral restraining elements of the projectile.
Because the submunitions are made free to be drawn radially away from one another, both the action and the reaction forces are directly applied by the spring to submunitions only, namely to at least two submunitions of the layer. There is not a central supporting element to provide for the reaction force. This results in an improvement in space, weight, simplicity of manufacture, assembly and cost of the projectile with respect to the prior art.
The direct application of both the action and the reaction forces to submunitions only, which allows for the mutual drawing away of the content, is made possible in that the spring of each layer in its preloaded condition inside the projectile is oriented on a plane substantially perpendicular to the longitudinal axis of the projectile, that said spring is in contact, radially inwards, directly and only with submunitions of the layer, at least with two of them and, radially outwards, with the peripheral restraining elements of the projectile.
The invention will be better understood from the following description, given merely as an example and therefore in no limiting sense, of two embodiments thereof, referring to the accompanying drawings, in which:

Fig. 1 shows a submunition projectile of the spinless type, partially cut away to show the arrangement of the submunition inside it;
Fig. 2 is a cross-sectional view thereof taken along the line 2-2 of Fig. 1;
Fig. 3 shows the operation at the opening step of the device according to the invention in the case of the projectile of Figs. 1 and 2 in which three submunitions in each layer are provided;
Fig. 4 is a side view of only the flat spring of Fig. 3, seen at the same moment illustrated in Fig. 3; and
Fig. 5 shows the operation, at the opening step, of a change in the device according to the invention, in the case in which five submunitions in each layer are present.

In Figs. 1 and 2 there is shown a submunition projectile, of the spinless type, provided with the device for the mutual drawing away of the submunitions according to the invention. In said projectile 1 the submunitions 2 are disposed in five layers, each layer consisting of three submunitions 2. The submunitions of each layer are kept in position by three spacer elements 3, generally of plastic material shaped so as to mate the outer surface of the submunitions 2 and the inner surface of the shell of the projectile 1. These elements 3 are not indispensable and anyway we will consider them as a part of the shell of the projectile 1 and not as a part of the device for the mutual drawing away of the submunitions 2.
Disposed between the submunitions 2 of each layer is a flat spring 4, in the preloaded state, shaped as illustrated in Fig. 1, where the spring 4 encompasses almost completely the uppermost submunitions and partially the other two lower submunitions. This spring 4 is nothing but a piece of spring steel strip and has normally a constant width and thickness. It may, as well, however, for particular requirements, have a variable width and/or thickness.
The springs 4 are disposed normally substantially in the central portion of each layer of submunitions 2 even though it is not impossible that, in order to obtain particular effects, f.e. a spin of the submunitions, this position may be not central.
While not indispensable for the operation of the device according to the invention, the spacer elements 3 have on their concave faces, turned towards the submunitions 2, grooves adapted to receive the spring 4.
Let us see briefly now how the device for mutually drawing away the submunitions shown in Figs. 1 and 2 operates.
Once the projectile 1 has been thrown and has reached a predetermined point of its trajectory, the action of an ejection charge intervenes which is normally enclosed in the tip 5 of the projectile 1. The action of this ejection charge causes the tail 6 of the projectile 1 to detach and ejects successively the various layers of submunitions 2 from the rear side of the projectile 1. Once a layer of submunitions 2 has been ejected, the spring 4 is free to act, whereby, because of the action of the spring, the various submunitions are thrown radially with respect to the trajectory of the projectile 1. The first steps of the stretching out of the spring 4 and of the mutual drawing away of the three submunitions forming one layer are shown diagrammatically in Fig. 3, in which, for the sake of clearness, the longitudinal dimensions of the spring 4 have been partially altered. The arrows of Fig. 3 indicate the projection directions of the individual submunitions under the action of the spring 4.
Fig. 4 is a side view, looking from the bottom of the drawing sheet, of the sole spring 4 at the same instant shown in Fig. 3.
In the embodiments illustrated so far there are only three submunitions for each layer. It is apparent that the number of submunitions can be even higher. In particular, in Fig. 5 there is shown a situation similar to that of Fig. 3, in which, however, the submunitions of each layer are five. Also in this figure, for the sake of clearness, the longitudinal dimensions of the spring 4 have been partially altered.
From the above stated it is apparent that the conformation of the spring can be fitted, within certain limits, to a number of submunitions different from that of the two embodiments described. In the case in which the submunitions in each layer are quite a lot, it may be possibly made recourse to the use of two or more springs to obtain the desired drawing away effect of the submunitions.
Always in the case of a plurality of submunitions in each layer, it will be in addition possible to strengthen some sections of the . spring, f.e. by changing its length, so that some submunitions receive a radial thrust higher than the others, or it can be arranged that only the central submunitions of the layer undergo the action of the spring 4, while the other more outer will be pushed radially by the action of said more inner submunitions. In other words, it is not required that all submunitions 2 contact the spring 4 to have the desired radial thrust effect.
It is apparent from the above stated that the conformation of the spring used, conditions the mutual radial throw direction of the individual submunitions. Therefore, this conformation of the spring must be studied so as to obtain a good radial distribution of the throw directions of the submunitions.
It has been spoken up to now about a spinless projectile, of the type used in mortars, and this because the device for the mutual drawing away of the submunitions according to the invention has been studied particularly for these types of projectiles. However, the device according to the invention can be also used in submunitions projectiles provided with a spin in which the effect of the centrifugal force is insufficient to obtain the desired distribution of the submunitions on the ground.
From the above stated it appears that by means of the device according to the invention there is obtained a substantial increase in the coverage on the ground of an individual subammunition projectile, whereby the efficiency of the subammunition projectile is substantially improved.

Claims

1. Device for drawing away the submunitions of a submunition spinless projectile or a submunition warhead in which the submunitions are disposed in parallel layers by means of a flat spring, characterized in that it comprises at least one flat spring (4, 4') for each submunition layer, said spring (4, 4') being disposed under preloaded conditions (1, 3) among the submunitions (2) of its respective layer and being adapted to stretch out when the submunitions (2) are ejected from the projectile (1) thus mutually drawing away radially the submunitions (2) from one another, and further characterized in that the spring (4) of each layer in its preloaded condition inside the projectile (1) is oriented on a plane substantially perpendicular to the longitudinal axis of the projectile, that said spring (4) is in contact, radially inwards, directly and only with submunitions (2) of the layer, at least with two of them and, radially outwards, with the peripheral restraining elements of the projectile (1).

2. Device as claimed in claim 1, characterized in that the flat spring (4) encompasses a portion of the side surface of the submunitions (2) with which it is in contact.

3. Device as claimed in the preceding claims, characterized in that the flat spring (4) is also in contact with the inner wall of the projectile (1).

4. Device as claimed in claims 1 and 2, characterized in that the flat spring (4) is in contact with the spacer elements (3) disposed between the inner wall of the projectile (1) and the submunitions (2).

5. Device as claimed in claim 4, characterized in that the spacer elements (3) disposed between the inner wall of the projectile (1) and the submunitions have on their concave faces in contact with the submunitions grooves adapted to receive the flat spring (4).

6. Device as claimed in any of the preceding claims, characterized in that the flat spring (4) has a variable width.

7. Device as claimed in any of the preceding claims, characterized in that the flat spring (4) has a variable thickness.