GB2480354A

GB2480354A - Shutter plate assembly

Info

Publication number: GB2480354A
Application number: GB201104590A
Authority: GB
Inventors: David Peter Plewka; Gordon William Flaws
Original assignee: Wallop Defence Systems Ltd
Current assignee: EST Defence Company UK Ltd
Priority date: 2010-05-11
Filing date: 2011-03-18
Publication date: 2011-11-16
Anticipated expiration: 2031-03-18
Also published as: GB201007859D0; GB2480277B; GB2480277A; GB2480354B; GB2480355A; GB2480355B; GB201104590D0; WO2011141724A1; GB201104608D0

Abstract

A shutter plate assembly (16) adapted, in use, to initiate a countermeasure cartridge, comprises a body portion incorporating an orifice (27) and a leaf member (22). The leaf member (22) is slidably attached to said body portion by a first snap-fitting (25) means which, in use, is movable from a first position that prevents the communication of hot gases through said orifice (27), to a second position that allows the communication of hot gases through said orifice (27).

Description

A Countermeasure Cartridge

Field of the Invention

The invention relates to air countermeasure cartridges.

Background to the Invention

A known air countermeasure device is a 55mm countermeasure cartridge, which is typically used by the Tornado and Typhoon countermeasure systems.

The countermeasure cartridge is assembled by attaching the base plate / film wire / squib housing sub-assemb'y onto a pay'oad sub-assemb'y. The pay'oad sub-assemb'y is then inserted into an open end of a cartridge's outer case. The outer case, manufactured from a base plate, tube and 0-ring, are crimped together. The strength and ductility of the tube is a critical feature in a design and requires close quality control.

An external contact printed circuit board (PCB) is attached to the outer case via four small screws. However, prior to the fitting of the PCB, a void which exists underneath the PCB is filled by two potting operations to provide an environmental seal.

A film wire/foil originating from the contact PCB, for communicating the firing pulse to the squib housing, is attached to the squib housing via two screws which have exposed threads that are peened over (an edge burred over). In operation the film wire/foil is designed to tear to allow the squib and squib housing to be ejected with the payload. This ensures that the firing circuit will have been broken when the dispenser interrogates the post-firing resistance of the cartridge. When assembling the cartridge, the operator has to pass a cut through the film wire to create "weak" points and can lead to problems with the quality of the product.

The shutter mechanism for the known cartridge incorporates the following features: * A take-over cup which is peened (an edge burred over) in place; * Gunpowder required for the ejection charge is retained within the mechanism via a paper disc and a pressed-in ferrule; * Two sealing O'-rings are fitted onto the shutter; * A squib device is g'ued into the housing; * A squib housing is attached to the shutter block via two screws; * A sprung loaded shutter-spring follower is peened (an edge burred over) into the housing; * An additional booster cup is fitted into the assembly; and * A dry [ubricant is app[ied to the shutter.

The aluminium payload container is designed to be produced in a "soft" condition which results in a component which is prone to damage and requires a high level of protection when being transported from the supplier.

The way in which the cartridge has been designed and manufactured, results in a considerable component tolerance build up before fitting the end cap, the resulting void within the cartridge is filled with a number of packing pieces. The void within the cartridge is gauged, and then the appropriate packing pieces are then selected and inserted about one end of the payload to fill the void within the cartridge.

An end cap and spacing washers are then fitted close to the outer case.

The completed cartridge has to be inspected by X-ray to confirm no solder inclusions or twisted film wires.

Summary of Invention

In a first broad independent aspect the invention provides a method of assembling a countermeasure cartridge comprising the steps of * Disposing an annular bonding member about a payload container assembly; * Inserting said payload container assembly into an outer case of said cartridge; * Rotating said payload container assembly in relation to said outer case, whereby a protrusion from a shutter sub-assembly of said payload container assembly cooperates with a recess / orifice of a seal plate sub-assembly incorporated within said outer case and facilitates the alignment of an electrical contact protrusion from said shutter plate assembly with an electrical contact portion of said seal plate sub-assembly; and * Crimping said outer case to said payload container via said bonding member.

This method provides a fast end efficient means of assembling a countermeasure cartridge from independent sub-assemblies. It allows a relatively low skilled operator to repeatedly assemble countermeasure cartridge in which the payload contacts are reliably aligned with the contacts of the outer case, with out any complicated assembly procedure, therefore ensuring that the firing signal is reliably communicated through the cartridge case to the squib device. The annular bonding member ensures that both the outer case of the cartridge and the payload container are maintained at the same potential difference, therefore preventing any potential difference between the sub-assemblies, which may unintentionally activate the device. The annular bonding member may be typically in the form of a conductive clip.

Preferably, further comprising the step of attaching an electrical conductor to a first circuit board. This provides a means of electrically communicating the firing pulse signal applied to the cartridge to the contact PCB.

Preferably, further comprising the step of disposing a first annular sealing member within an outer channel of said seal plate sub-assembly, whereby, in use, said first annular sealing member abuts both the outer edge of said seal plate and the inner surface of said outer case. This provides a seal which prevents the movement of hot gases passing around the seal plate sub-assembly and potential damaging the interface PCB, which interfaces the cartridge with the countermeasure dispenser.

Preferably, further comprising the step of disposing a shaped protrusion projecting from said seal plate assembly which cooperates with an identical recess within said outer case of said cartridge. This configuration provides a means of preventing any rotational movement of the seal plate assembly, in relation to the outer case of the cartridge, when the cartridge is exposed to vibrations.

Preferably, further comprising the step of attaching said seal plate sub-assembly to said outer case of said cartridge, via a snap-fitting means. This configuration provides a means of attaching the seal plate assembly to the outer case of the cartridge, therefore providing a method of assembly which is quick, clean and without the use potting compounds, adhesives pins or screws. The assembly can also be carried out by a relatively low skilled operator. Furthermore, the snap-fitting means provides a cost effective method of attaching the seal plate assembly to the case of the cartridge.

Preferably, further comprising the step of attaching said electrical conductor to a second circuit board. This provides a means of communicating the firing signal from the external interface PCB, which engages the countermeasure dispenser, to the contact PCB.

Preferably, further comprising the step of disposing said electrical conductor from said second circuit board, through said snap-fitting means, thereby facilitating the attachment of said electrical conductor to said first circuit board. This provides a means of routing the electrical conductor between the contact PCB and the external interface PCB without compromising the integrity of the seal. The conductor is routed through the snap fit mounting hole which eliminates the requirement for a separate hole within the seal plate assembly.

Preferably, wherein said method comprises the step of locating a first annular sealing member between said first circuit board and said one end of said outer case, whereby said first circuit board is crimped onto one end of said outer case. This provides a means of permanently attaching and sealing the external contact PCB to the outer case, therefore providing an environmental seal which prevents any moisture from getting into the void which is located beneath the external interface PCB. Furthermore, the seal also eliminates the requirement for potting the interface PCB to prevent the ingression of moisture.

Preferably, further comprising the step of incorporating a pad which includes first and second adhesive surfaces; whereby said first surface attaches said pad to said seal plate assembly and said second surface attaches said first circuit board to said pad. This provides the means of attaching the contact PCB to the seal plate assembly during assembly process. Therefore, allowing the routing of the electrical conductors whilst assembling and attaching the seal plate assembly to the outer case of the cartridge.

Preferably, a method of assembling a countermeasure cartridge substantially as described herein.

In a second broad independent aspect the invention provides a shutter plate assembly adapted, in use, to initiate a countermeasure cartridge, the assembly comprising a body portion incorporating an orifice and a leaf member; wherein said leaf member is slidably attached to said body portion by a first snap-fitting means which, in use, is movable from a first position that prevents the communication of hot gases through said orifice, to a second position that allows the communication of hot gases through said orifice. This configuration provides a means of assembling a shutter plate mechanism for a countermeasure cartridge without the use of potting compounds, adhesives, pins or screws. The assembly can be carried out by a relatively low skilled operator. The assembly provides a quick, easy and cost effective method of assembling shutter plate.

Preferably, wherein said first snap-fitting means further comprises a cavity within said body portion which incorporates a slot that cooperates with a snap-fitting protrusion on said leaf member. This provides a means of attaching the leaf member to the body portion by the operator inserting the leaf into the cavity. The protrusion locates within a slot within the cavity, which allows the leaf to be slidably attached to the body portion.

Therefore, reducing the required level of skill required to assemble the shutter assembly, which requires no screws pins.

Preferably, wherein said leaf member further comprises a cavity for holding a resilient spring member. This provides the means of biasing the leaf member in predetermined position.

Preferably, further comprising a squib sub-assembly wherein said squib sub-assembly is attachable to said body by a second snap-fitting means. This provides a means of attaching the squib sub-assembly to the body portion without the use of glues, potting or pinning. Therefore, reducing the assembly time and operator skill required for assembling the shutter plate assembly whilst improving efficiency.

Preferably, wherein said squib sub-assembly further comprises an electrical contact means for communicating a firing signal to a squib device. This provides a means of communicating the firing signal from outer case assembly, to the squib device located within the shutter plate assembly. This may be typically in the form of sprung loaded electrical contact pin.

Preferably, further comprising a high friction insert which cooperates with said squib device. This provides a means of attaching the squib device to the shutter plate assembly, while also maintaining a seal which contains the hot gases from the squib device. The hot gases are generated when the squib device is initiated.

Preferably, wherein said body portion further comprise a retaining means for retaining said squib device within said high friction insert. This provides a means of mechanically retaining the squib device in position, during intense vibration, therefore preventing the squib device from being shaken loose. The retaining means may be in the form of a retaining clip.

Preferably, wherein said retaining means is a clip which is attachable to said body portion by a third snap-fitting means. This provides a means of attaching the retaining means to the body portion without the use of potting, adhesives, pins or screws. Therefore, reducing the assembly time and operator skill required for assembling the shutter plate assembly whilst improving efficiency.

Preferably, wherein said retaining means is polarised to facilitate the engagement of said third snap-fitting means. This provides the means of ensuring that the retaining means can only be fitted to the body portion of the shutter assembly in one position. Therefore, when the clip is located it is in the correct position which locks the squib device in to position.

Preferably, wherein said body portion further comprises a second cavity incorporating a plurality of sides which in use, retains a pyrotechnic device. This provides the means of attaching a pyrotechnic device which is pressed into the body portion of the shutter assembly. Therefore, material from the body portion is deformed and is displaced in the corner regions of the cavity, which prevents shards or burrs from forming. The resulting friction may cause a safety hazard if the shards or burrs are allowed to rub against the pyrotechnic device.

Preferably, wherein said body further comprises a third cavity which, in use, holds a gunpowder charge, whereby said gunpowder charge is retained by a closing member. This provides a means of incorporating the ejection charge required for dispensing the countermeasure payload from the cartridge without the use of paper discs and pressed in ferrules. Therefore, reducing the time and skill required for assembling the shutter plate assembly. . The closing member may be in the form of a friction fitting bung.

Preferably, a countermeasure cartridge comprising a shutter plate assembly.

Preferably, a countermeasure payload assembly comprising a shutter plate assembly Preferably, a method resulting in the assembly of a shutter plate assembly.

Preferably, shutter plate operated system.

In a third broad independent aspect the invention provides a seal plate assembly adapted, in use, to initiate a countermeasure cartridge, the device comprising a body portion incorporating a snap-fitting means; wherein said seal plate assembly is fitted to an outer case via said snap-fitting means. This configuration provides a means of assembling a seal plate mechanism for a countermeasure cartridge without the use of potting compounds, adhesives, pins or screws. The assembly can be carried out by a relatively low skiLled operator. The assembly provides a quick, easy and cost effective method of assembling shutter plate. The seal plate assembly can be assembled away from the manufacturing environment.

Preferably, further comprising a circuit board incorporating an electrical contact, which in use, communicates an initialising pulse to a shutter plate assembly. This provides a means of communicating an external firing pulse to the squib device residing within the adjacent shutter plate assembly.

Preferably, further comprising an annular sealing member disposed within an outer recess, wherein said annular member abuts the outer surface of said seal plate and inner surface of said outer case. This provides an outer seal about the seal plate assembly which prevents the hot gases from the ejection charge reaching the bottom interface board that may damage the cartridge and impede the ejection of the cartridge.

Preferably, further comprising a key portion which cooperates with a keyway incorporated within said circuit board. This provides the means of correctly positioning the circuit board onto the seal plate assembly, so the circuit board is aligned with the contacts of the shutter plate assembly.

Preferably, further comprising a recess which cooperates with a locating supporting member from a shutter plate assembly. This provides the means of aligning the shutter plate assembly on top of the seal plate assembly, so that the contacts of both assemblies are aligned with each other to facilitate the communication of the firing pulse.

Preferably, further comprising an aperture, which, in use, facilitates the routing of an electrical conductor from a circuit board to the external interface of said cartridge. This provides the means of routing the electrical conductor through a hole within the seal plate assembly without interfering with the outer seal of the seal plate assembly.

Preferably, further comprising a protruding portion configured into a shape incorporating a plurality of sides and which, in use, co-operates with a recess within the inner surface of said cartridge. This provides a means of locating the seal plate assembly on to the outer case and prevents the seal plate from rotating when under severe vibration, without the use of potting materials or adhesives.

Preferably, a countermeasure cartridge comprising a seal plate assembly.

Preferably, an outer case of a countermeasure cartridge comprising a seal plate assembly.

Brief Description of Figures

Figure 1 shows an exploded, perspective view of the countermeasure cartridge, in accordance with the preferred embodiment of the invention.

Figure 2 shows a cross sectional view of the assembled countermeasure cartridge, in accordance with the preferred embodiment of the invention.

Detailed Description of the Figures

Figure 1 shows an exploded view of a countermeasure cartridge, generally indicated by 1.

The cartridge incorporates two main sub-assemblies, which are an outer case sub-assembly 2 and a pellet (a pellet formed countermeasure payload) container sub-assembly 3. The outer case assembly 2 incorporates a metallic tubular body 4, typically constructed from an aluminium alloy, which is formed from a one-part extrusion. The outer case sub-assembly 2 is open at one end 5 for receiving the seal plate sub-assembly 6 and the pellet container sub-assembly 3. The seal plate sub-assembly 6 is a plastics / composite disc assembly, which incorporates a circular recess 7. The circular recess 7 further incorporates an orifice 8 and a polarising key 9. The orifice 8 enables one or more electrical conductors (such as electrical wires or ribbon / foil conductors to pass through the seal plate assembly 6) for the connection to an external interface printed circuit board (PCB) 10, which receives the firing pulse signal from an external countermeasure system. The key 9 is a protrusion, which cooperates with a keyway 11 located on the outer peripheral edge of a circular contact PCB 12. The circular contact PCB 12 is located and held within the circular recess 7 via pad (not shown) which has an upper self-adhesive surface and a lower self-adhesive surface. The seal plate sub-assembly 6 further incorporates an annular channel 13 about its peripheral edge for locating an annular seal, such as an o' ring (not shown). An array of three recesses 14 (only two are shown) which are located within a second annular recess 1 5 that is adjacent to recess 7. The three recesses 14 are spaced about the annular recessl 5 in a unique combination, which enables the fitting of the pellet container sub-assembly 3 to the seal plate sub-assembly 2 in a configuration, which aligns the eEectrical contacts of the squib device sub-assembEy (not shown, -housed within the shutter plate assembly 16) with the electrical contacts on the contact PCB 12.

At the opposite end of the tubular body 4, the interface PCB 10 is located within an annular recess 30 (see figure 2), incorporated within an end face 1 7 of the tubular body 4.

The interface PCB lOis crimped into the annular recess 30 (see Figure 2) of end face 17, therefore permanently attaching and sealing the interface PCB 10 to the tubular body 4.

The pellet container sub-assembly 3 incorporates a metallic tubular body 18, which is typically of an aluminium alloy, formed from a one-part extrusion.

The cylindrical body 18 incorporates a closed portion 19, which incorporates an array of three circular recesses 20. The spacing between the first and second recesses is 100 degrees, the spacing between the second and third recesses is 120 degrees and the spacing between the third and first recesses is 140. The recesses locate and cooperate with three matching locating spigots (not shown) protruding from the bottom surface of a plastics end cap 21. This configuration of recesses and matching spigots ensures that the pellet container sub-assemb'y 3 ocates within the outer case sub assemb'y 2, whilst a'igning and maintaining electrical contact between the two subassemblies.

The shutter plate assembly 16 further incorporates a leaf member 22, which cooperates with a cavity 23 within the shutter plate assembly 16. The leaf member 22 incorporates two cylindrical cavities 24, which houses two spring members (not shown). Each cylindrical cavity 24 incorporates a snap fitting protrusion 25 on its outer surface, which cooperates with a groove within a cavity 23. The snap fitting protrusion is orientated along an axis.

The leaf member 22 has a width to length ratio, which would cause the leaf member 22 to jam sideways if any lateral rotation is incurred during its movement between two positions within the cavity 23. The leaf member 22 incorporates a rectangular key 26, which cooperates with a rectangular keyway within the cavity 23 that prevents any lateral rotation of the leaf member 22.

The shutter plate assembly 16 is shown to incorporate an orifice 27, which communicates the hot gases from the take-over cup 29 to the pellet payload 28, and thereby subsequently iriitialises the pellet payload 28. The take-over cup 29 is pressed in to a recess (not shown) within the shutter plate assembly, which incorporates a plurality of sides, typically eight sides in the form of an octagon shape. The plurality of sides enables a tight and permanent fitting of the take-over cup within the shutter plate assembly 16, as the plastics material displaced during the insertion is pushed into the corners between the sides to ensure a tight fit, which will not shake loose when exposed to excessive vibrations.

Furthermore, no burrs or chards are produced which may cause the unintended activation of the take over cup 29 through any means of friction / static electricity.

Figure 2 shows the same countermeasure cartridge 1 as illustrated within Figure 1. The countermeasure cartridge 1 shows the pellet container sub-assembly 3 fully assembled and inserted within the cartridge's outer case sub-assembly 2. The external interface PCB 10 is shown to be crimped into one end 1 7 of the cartridge's outer case sub-assembly 2 and resides within a recess 30, which also accommodates an annular seal 31, such as an "0" ring, which environmentally seals the interface PCB 10 to the outer case end 17.

The outer case sub-assemb'y 2 is shown to incorporate an interna' wafl 32, which incorporates a central orifice 33 that enables the seal plate sub-assembly 6 to be snap-fitted to the outer case assembly 2 via the expandable head of a snap fitting means 34.

The snap fitting means 34 is located upon a protrusion 35, which has a plurality of sides.

The seal plate sub-assembly 6 is shown to be connected within a matching recess 36 within the internal wall 32. The plurality of sides prevents the seal plate sub-assembly from rotating when exposed to vibrations. The contact PCB 12 is shown to be assembled and attached to the seal plate sub-assembly 6 via a pad (pad not shown). The seal plate sub-assembly 6 incorporates an outer annular seal 41 which seals the seal plate sub-assembly 6 to the inner surface of the cartridge's outer case sub-assembly 2. The shutter plate sub-assembly 16 of the pellet container sub-assembly 3 is shown to be located on the seal plate sub-assembly 6.

At the opposite end of the payload is a second pellet supporting ring [not shown], which is also typically formed from a rubber material that abuts both the flat end face of the pellet payload 28 and the face of the outer annular flange 37. The pellet supporting rings prevents the pellet payload 28 from moving within the pellet container 18 and therefore making contact with the inner surface of the cylindrical container 18. Therefore, preventing the pellet payEoad 28 from being exposed to any friction / static eEectricity means, which may unintentional activate the pellet payload 28. The pellet payload's length will vary due to the manufacturing process and the densities of the materials used.

This results in the gap between the end face of the pellet payload 28, and the face of the outer annular flange 37 to vary, therefore various thicknesses of the second supporting ring [not shown] will be required accordingly. The second supporting ring [not shown] may be provided in a range of thicknesses, such as 1.5mm, 2.5mm, 3.5mm and 4.5mm, to fill the gap. Once the pellet payload 28 has been inserted into the pellet container 18, along with the two pellet supporting rings 40, the shutter plate assembly 16 is aligned in position on top of the second pellet supporting ring [not shown]. The top surface of the second pellet supporting ring [not shown] protrudes from the open end of the pellet container when in position. The protrusion is dependent upon the length of the pellet payload 28 and may range from 0.1mm to 1.1mm in relation from the outer edge of the pellet container 18.

The shutter plate assembly 16 is then pressed into the pellet container 18, which compacts the pellet payload between the two supporting rings. This prevents the movement of the pellet payload 28 within the pellet container 18. The loaded pellet container is then crimped onto the shutter p'ate assemb'y's outer annu'ar flange 37, which incorporates a reversed angle and therefore maintaining the cylindrical body 18 onto the shutter assembly 16.

The pellet container 18 incorporates a groove 41 in close proximity towards the closed end of the container 18. Located within the grove 41 are two adjacent seals one is a rubber environmental seal 38, the other is formed from a 0.6mm gauge wired bonding dip 39, which incorporates a plurality of sides, such as an octagon / decagon shape. The two seals are configured so that the environmental seal 38 is on the outer most edge and prevents any environmental contamination of the bonding clip 39. The pellet container 18 incorporates a pellet supporting ring 40, which is typicalLy formed from a rubber material that supports a pellet's pointed nose end whilst within the container 18.

In use, the countermeasure cartridge is assembled by inserting a fully assembled pellet container sub-assembly into a fully assembled outer case sub-assembly of the cartridge.

The pellet container sub-assembly is then rotated in relation to the outer case sub-assembly, in which the locating spigots protruding from the shutter assembly locate within the dedicated recesses of the seal plate sub-assembly. This configuration ensures that the sprung loaded electrical contacts of the sear plate sub assembly are aligned and in contact with the electrical contacts of the squib device sub assembly, which is incorporated within the shutter plate assembly. Once the pellet container sub-assembly has been fully inserted into the outer case it is then crimped to the outer case by an array of metal deforming punches, which crimp the outer case to the pellet container sub-assembly via a number of dots along the same circular axis as the bonding clip.

An end cap is fitted to the closed end of the pellet container, via an array of three pins which cooperate with an array of 3 holes! recesses located within the closed end of the pellet container. The pins and holes interact to form a friction fitting means of retaining the cap in position without the use of packing/spacing components, which are utilised in the assembly of known countermeasure cartridges.

The leaf member is snap fitted to the shutter plate assembly's body via two slots, which cooperate with the protrusions from the outer edges of the leaf device, which extend in a linear direction.

The shutter plate assembly incorporates a squib device assembly (also known as a contact block assembly), which is snap fitted to the shutter plate assembly via a contact block that incorporates two sprung load pins. The contact block is configured in a triangular shape in which the top angle incorporates a notch that polarises the contact block so that it can be fitted in one orientation only. A squib device is attached to the contact pins and is then inserted into a high friction rubber insert which retains the squib within the shutter plate assembly, while also maintaining a seal that contains the hot gases from the squib device.

The hot gases are generated when the squib device is initialised. The squib is also mechanically retained by a polarised U'-shape clip which incorporates a central slot which retains the squib within the rubber insert under severe vibration. The pins of the squib assembly are sprung loaded, which therefore ensure that they make a good contact with the contact portion of the seal plate assembly. The shutter plate assembly also incorporates a well for housing a charge of gun powder. The gun powder is enclosed within the well via a friction fitting rubber bung.

The shutter plate assembly's leaf assembly, when pushed in does not allow the communication of hot gases from the take-over cup to the pellet payload and acts a safety mechanism. Therefore, when the shutter plate assembly is inserted into the outer plate sub-assembly, the leaf member is pushed into the isolating position.

The firing pulse from the system, via the external interface PCB, is communicated through electrical conductors, which subsequently communicates the firing signal to the internal contact PCB. The internal contact PCB then subsequentLy communicates the firing pulse to the contact pins of the shutter plate assembly. The firing pulse is then subsequently communicated to the squib device incorporated within the shutter plate assembly, whereby the firing pulse activates the squib device. The initiation of the squib device then burns the black powder within the black powder charge. The black powder is retained within the black powder reserve via a friction fitting rubber bung. The burning of the black powder charge generates a substantial amount of hot gases, which expands and jettisons the pellet container sub-assembly away from the outer case, into free space away from the platform. The burning of the bLack powder also initialises the take-over cup, which, after a predetermined period of time, will initiate a burn that is subsequently communicated to the pellet payload. However, the communication of the burn to the pellet payload can only be achieved when the pellet container sub-assembly has been jettisoned from the outer case. In doing so, the leaf member incorporated within the shutter plate assembly, which is attached to the pellet container, will move to a position that allows the burn from the take-over cup to communicate to the pellet payload and therefore subsequently initialises the pellet payload If the pellet container sub-assembly is not jettisoned from the outer case, the leaf member will be held in a position which prevents the communication of the burn to the pellet payload, therefore preventing the initialisation of the pellet payload.

It is intended that the cartridge may be supplied as a kit, which is assembled by personnel that have no specialist assembly skills, as required for assembling conventional countermeasure cartridges. Or alternatively, the cartridge may be supplied as a fully assembled unit.

The kit consists of: * An outer case (fully assembled with a seal plate and PCB boards); * A Shutter plate assembLy (not including the squib device sub-assembly); * A pellet container; * An end cap; * An environmental seal; * A bonding seal element; * A nose supporting ring for the pellet payload; and * A selection of rear supporting rings (typically four rings of various thicknesses, such as 1.5mm, 2.5mm, 3.5mm and 4.5mm).

It is also the intention to include some variability on the configuration of the kits, therefore the kits may be supplied with the pyrotechnic sub-assembly and/or with a pellet countermeasure pay[oad but this depends on the safety criteria of the user as these are a[ classed as pyrotechnic devices and warrant extreme safety measures.

The advantages in summary of the invention are:

* It substantially reduces the time for producing a countermeasure cartridge; * It offers flexibility in configuring the cartridge to a new configuration by the interchanging of the peLlet container incorporating a pellet countermeasure payload; and * It could be fully assembled quickly and easily using snap fitting methods of assembly which incorporates no potting or any other processes which take a long time to cure.

Therefore, the time and materials required to produce this device makes it an efficient, cost effective solution which is easy to manufacture and does not require especially skilled operatives to carry out the task of assembly.

Claims

Claims 1. A shutter plate assembly adapted, in use, to initiate a countermeasure cartridge, the assembly comprising a body portion incorporating an orifice and a leaf member; wherein said leaf member is slidably attached to said body portion by a first snap-fitting means which, in use, is movable from a first position that prevents the communication of hot gases through said orifice, to a second position that allows the communication of hot gases through said orifice.
2. An assembly in accordance with claim 1, wherein said first snap-fitting means further comprises a cavity within said body portion which incorporates a slot that cooperates with a snap-fitting protrusion on said Leaf member.
3. An assembly in accordance with either of the preceding claims wherein said leaf member further comprises a cavity for holding a resilient spring member.
4. An assembly in accordance with any of the preceding claims further comprising a squib sub-assembly wherein said squib sub-assembly is attachable to said body by a second snap-fitting means.
5. An assembly in accordance with claim 4, wherein said second snap-fitting means further comprises an aperture within said body portion which cooperates with a snap-fitting protrusion on said squib sub-assembly.
6. An assembly in accordance with either of the claims 4 or 5, wherein said squib sub-assembly further comprises an electrical contact means for communicating a firing signal to a squib device.
7. An assembly in accordance with any of the preceding claims further comprising a high friction insert which cooperates with said squib device.
8. An assembly in accordance with any of the preceding claims wherein said body portion further comprise a retaining means for retaining said squib device within said high friction insert.
9. An assembly in accordance with claim 8, wherein said retaining means is a clip which is attachable to said body portion by a third snap-fitting means.
10. An assembly in accordance with claim 9, wherein said third snap-fitting means further comprises an edge within said body portion which cooperates with a snap-fitting protrusion on said retaining means.
11. An assembly in accordance with any of the preceding claims 8 to 10, wherein said retaining means is polarised to facilitate the engagement of said third snap-fitting means.
12. An assembly in accordance with any of the preceding claims wherein said body portion further comprises a second cavity incorporating a plurality of sides which in use, retains a pyrotechnic device.
13. An assembly in accordance with any of the preceding claims wherein said body further comprises a third cavity which, in use, holds a gunpowder charge, whereby said gunpowder charge is retained by a closing member.
14. A countermeasure cartridge comprising a shutter plate assembly in accordance with any of the preceding claims.
1 5. A countermeasure payload assembly comprising a shutter plate assembly in accordance with any of the preceding claims 1 to 13.
16. A method resulting in the assembly of a shutter plate assembly in accordance with any of the preceding claims 1 to 13.
1 7. A shutter plate operated system in accordance with any of the preceding claims 1 to 13.
18. A shutter plate assembly as hereinbefore described and I or illustrated in any appropriate combination of the accompanying text and I or Figures.