SABOT STRIPPING

Abstract: Barrel assembly (10) includes an array of individual barrels (11) with each barrel (11) including a sabot stripping structure (23) and a sabot receiver (28) arranged to collect and prevent sabots (14) from exiting muzzle (20) of barrel (11). Each barrel (11) incoporates a multiplicity of sabotted projectiles (12) stacked axially within barrel (11) and a multiplicity of interposed corresponding propellent charges (16). Sabotted projectiles (12) each comprise projectile (13) and an associated sabot (14) detachably engaged with projectile (13). Detonation of a leading propellant charge (16) urges following sabotted projectiles (12) into sealing engagement with respective barrels (11).

Description: SABOT STRIPPING The present invention relates to munitions and firearms, in particular the present invention relates to a sabotted round, to a barrel assembly for launching a sabotted round and to such a barrel assembly incorporating a multiplicity of sabotted projectiles stacked axially within the barrel assembly. Sabotted projectiles are employed in applications requiring projectiles to have high kinetic energies, such as in penetrating armour plate on ships and tanks, and for long range applications. A sabotted projectile generally incorporates a sub-calibre projectile that is adapted by a relatively lightweight sabot to provide a gas seal with the bore of the barrel. The sabot permits the propellant charge to exert the propulsive force over a larger area and thus the sub-calibre projectile and relatively lightweight sabot achieves a greater in-barrel velocity than a full diameter projectile. The sabot is separated from the sub-calibre projectile, typically after it exits the muzzle of the barrel and in one configuration can be adapted to disintegrate after it emerges from the muzzle of the barrel. Other sabot configurations employ different systems for separating the sabot from the sub-calibre projectile. The differing centrifugal forces generated in the sabot and sub-calibre projectile by a rifled barrel have been employed in sabot designs to separate the sabot from the sub-calibre projectile. The aerodynamic drag on the sabot relative to that on the sub-calibre projectile in other configurations may be used to separate the sabot from the sub- calibre projectile. Barrel assemblies having a plurality of projectiles stacked axially within a barrel together with discrete selectively ignitable propellant charges for propelling the projectiles sequentially through the muzzle of the barrel allow the projectile to be fire at extremely high rates. Firing sabotted rounds at such high rates increases the likelihood of a projectile striking the sabot from a previously fired round and being rendered ineffective. We have now found a configuration that minimises the likelihood of a projectile striking the sabot from a previously fired round. Accordingly, in one aspect the present invention provides a barrel assembly incorporating a multiplicity of sabotted projectiles stacked axially within the barrel assembly and a multiplicity of corresponding propellant charges disposed therebetween wherein the barrel assembly includes a barrel having a muzzle and wherein said barrel includes a sabot stripping structure and a sabot receiver arranged whereby sabots are prevented from exiting the muzzle of the barrel and wherein the multiplicity of sabotted projectiles comprise a multiplicity of projectiles and a multiplicity of associated sabots wherein the associated sabots detachably engage the projectiles whereby detonation of a leading propellant urges subsequent sabotted projectiles into sealing engagement with the barrel. In a second aspect the present invention provides a barrel having a muzzle and wherein said barrel includes a sabot stripping structure and a sabot receiver arranged whereby sabots are prevented from exiting the muzzle of the barrel. In a third aspect the present invention provides a sabotted projectile for stacking axially within a barrel assembly comprising a projectile and a sabot wherein the sabot detachably engages the projectile wherein detonation of a leading propellant in an axially stacked array urges subsequent sabotted projectiles into sealing engagement with the barrel. The present invention may utilise barrel assemblies capable of firing a controlled rapid fire sequence of projectiles and being of the general type described and/or illustrated in our earlier International Patent Applications, including PCT/AU94/00124 and PCT/AU96/00459. However other barrel assemblies incorporating discrete propellant charges for propelling respective sabotted projectiles stacked axially within the barrel assembly may be used in the present invention. The projectile may be round, conventionally shaped or dart-like and the fins thereof may be offset to generate a stabilising spin as the dart is propelled from a barrel that may be a smooth-bored barrel. Each projectile may include a projectile head and tail portion for at least partly defining a propellant space. The tail portion may include a spacer assembly that extends rearwardly from the projectile head and abuts an adjacent projectile assembly. The spacer assembly may extend through the propellant space and the projectile head whereby compressive loads are transmitted directly through abutting adjacent spacer assemblies. In such configurations, the spacer assembly may add support to the extension means that may be a thin cylindrical rear portion of the projectile head. Furthermore the extension means may form an operative sealing contact with the bore of the shell to prevent burn leakage past the projectile head. The spacer assembly may include a rigid collar that extends outwardly to engage a thin cylindrical rear portion of the malleable projectile head inoperative sealing contact with the bore of the shell such that axially compressive loads are transmitted directly between spacer assemblies thereby avoiding deformation of the malleable projectile head. It is preferred that each projectile has a bullet shaped head portion about which the sabot is positioned and a tail portion which extends rearwardly into abutting relationship with the leading end of the next adjacent trailing projectile whereby the stacked column of rounds are positively located in their operative positions in the barrel. This configuration allows for high volumes of propellant charges to be employed for each projectile thereby providing high kinetic energy to the projectile. Alternatively, the projectile charge may be form as a solid block to operatively space the projectiles in the shell or the propellant charge may be encased in metal or other rigid case which may include an embedded primer having external contact means adapted for contacting an pre-positioned electrical contact associated with the shell. For example the primer could be provided with a sprung contact which may be retracted to enable insertion of the cased charge into the shell and to spring out into an aperture upon alignment with that aperture for operative contact with its mating shell contact. If desired the shell may be consumable or may chemically assist the propellant burn. The sabot may be in the form of complementary wedging surfaces disposed on the projectile head respectively whereby the projectile head is urged into engagement with the bore of the barrel in response to relative axial compression between the spacer means and the projectile head. In such arrangement the projectile head and spacer assembly may be loaded into the barrel and there after an axial displacement is caused to ensure good sealing between the projectile head and barrel. Suitably the extension means is urged into engagement with the bore of the barrel. The barrel may be non-metallic and the bore of the barrel may include recesses that may fully or partly accommodate the ignition means. In this configuration the barrel houses electrical conductors which facilitate electrical communication between the control means and ignition means. This configuration may be utilised for disposable barrel assemblies that have a limited firing life and the ignition means and control wire or wires therefor can be integrally manufactured with the barrel. A cartridge may alternatively include ignition apertures in the barrel and the ignition means may be disposed outside the barrel and adjacent the apertures. The barrel may be surrounded by a non-metallic outer barrel that may form the sleeve which may include recesses adapted to accommodate the ignition means. The outer barrel may also house electrical conductors that facilitate electrical communication between the control means and ignition means. The outer barrel may be formed as a laminated plastics shell which may include a printed circuit laminate for the ignition means. The cartridge may have adjacent projectiles that are separated from one another and maintained in spaced apart relationship by locating means separate from the projectiles, and each projectile may include an expandable sealing means for forming an operative seal with the bore of the barrel. The locating means may be the propellant charge between adjacent projectiles and the sealing means suitably includes a skirt portion on each projectile which expands outwardly when subject to an in-shell load. The in-shell load may be applied during installation of the projectiles or after loading such as by tamping to consolidate the column of projectiles and propellant charges or may result from the firing of an outer projectile and particularly the adjacent outer projectile. The projectiles may be adapted for seating and/or location within circumferential grooves or by annular ribs in the bore or in rifling grooves in the bore and may include a metal jacket encasing at least the outer end portion of the projectile. The projectile may be provided with contractible peripheral locating rings which extend outwardly into annular grooves in the shell and which retract into the projectile upon firing to permit its free passage through the barrel. The electrical ignition for sequentially igniting the propellant charges of a barrel assembly may preferably include the steps of igniting the leading propellant charge by sending an ignition signal through the stacked projectiles, and causing ignition of the leading propellant charge to arm the next propellant charge for actuation by the next ignition signal. Ignition of the propellant may be achieved electrically or ignition may utilise conventional firing pin type methods such as by using a centre-fire primer igniting the outermost projectile and controlled consequent ignition causing sequential ignition of the propellant charge of subsequent rounds. This may be achieved by controlled rearward leakage of combustion gases or controlled burning of fuse columns extending through the projectiles. In another form the ignition is electronically controlled with respective propellant charges being associated with primers which are triggered by distinctive ignition signals. For example the primers in the stacked propellant charges may be sequenced for increasing pulse width ignition requirements whereby electronic controls may selectively send ignition pulses of increasing pulse widths to ignite the propellant charges sequentially in a selected time order. Preferably however the propellant charges are ignited by a set pulse width signal and burning of the leading propellant charge arms the next propellant charge for actuation by the next emitted pulse. Suitably in such embodiments all propellant charges inwardly from the end of a loaded barrel are disarmed by the insertion of respective insulating fuses disposed between insertion of respective insulating fuses disposed between normally closed electrical contacts, the fuses being set to burn to enable the contacts to close upon transmission of a suitable triggering signal and each insulating fuse being open to a respective leading propellant charge for ignition thereby. Any convenient trigger may be used in the present invention. Conventional trigger mechanisms may be employed. In such conventional trigger mechanisms the single firing event may be a single squeeze or depression of the trigger for the predetermined number of projectiles to be fired. There is no requirement to maintain the trigger in a depressed state for the predetermined number of projectiles to be fired as would be the case with an automatic weapon such as a machine gun in automatic mode. Other trigger mechanisms may be employed provided that a single firing event initiated directly by the user, or remotely, activates the trigger and fires the predetermined number of projectiles. The sabot associated with the projectile is desirably configured to prevent forward movement relative to the projectile whereby the sabot is accelerated integrally with the projectile through the barrel towards the muzzle. Preferably the sabot detachably engages the projectile whereby it is secured it against forward movement relative to the projectile. The sabot may be detachably secured to the projectile by a detent for engaging the projectile, for example into a corresponding recess. Alternatively the projectile may incorporate a detent for engaging the sabot, for example into a corresponding recess on the sabot. Preferably the detachable engagement of the sabot to the projectile does not inhibit its relative rearward movement along the projectile for stripping purposes whereby the projectile is not slowed significantly as the sabot is stripped from the projectile. In one embodiment complementary shallow inwardly directed annular ribs on the inner face of the sabot are located in shallow outer annular recesses in the projectile and which are disengaged by the stripping arrangement. Alternatively an annular concavity in the inner face of the sabot may be located about a complementary convex outer annular portion of the projectile which is disengaged by the stripping arrangement. In a further embodiment an interference fit, and preferably a tapered interference fit, between the projectile and the sabot may provide detachable engagement between the sabot and the projectile and which may be dislodged upon forward movement of the projectile relative to the sabot, such as that which occurs by the stripping arrangement. In a preferred embodiment each sabot comprises a pair of complementary continuous or segmented annular portions that engage through opposed tapered land portions whereby the outer annular portion is urged to expand radially upon commencement of movement of the inner annular portion therethrough to sealably engage the barrel. The inner annular portion is urged to move through the outer annular portion by the detonation of the propellant charge in front of the sabotted projectile in the array of axially stacked projectiles. A transversely extending flange may be provided on one annular portion to limit the relative longitudinal movement of the inner portion through the outer portion. In one embodiment, preferably this flange is a radial outwardly extending flange formed on the trailing end of the inner annular portion. The barrel assembly includes a barrel having a said barrel includes a sabot stripping structure and a sabot receiver arranged whereby sabots are prevented from exiting the muzzle of the barrel. Preferably the sabot stripping structure includes an inner sleeve portion at or adjacent the muzzle and disposed concentric with the barrel and through which the projectiles may pass and about which the sabots pass. The sleeve may be suitably tapered at its stripping end to urge the sabot away from the projectile into an annular barrel portion between the sleeve and the muzzle of the barrel. In a preferred form the barrel flares outwardly at the muzzle adjacent the stripping end of the sleeve to accommodate the sabots stripped from the sabotted projectiles substantially without radial compression of the stripped sabots. The inner sleeve portion may be supported by webs extending between the sleeve and the flared section of the barrel and between which stripped segments of the sabot may pass. The stripped sabot may pass through the annular barrel portion adjacent the sleeve. Preferably, the stripped sabot is retained in an annular storage portion of the muzzle end of the barrel so as to prevent its possible interference with a following one of a group of projectiles fired in rapid succession. The stripped sabot may be allowed to exit the barrel through a lateral aperture adjacent the muzzle. The braking of the stripped sabots in the barrel will provide a reaction that will assist in reducing the recoil action of a barrel assembly. This reaction may also be achieved by forcing a radial compression of the sabot during transit through the annular passage. In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawing wherein:- Fig. 1 is a diagrammatic sectional view of a typical multi-barrel firearm of the invention illustrated in diagrammatic cross-sectional form for explanatory purposes. The multi-barrel firearm 10 comprises a cluster of barrels 11 each supporting a plurality of rounds 12 in axially stacked relationship in the respective barrels 11. Each round comprises a projectile head 13 supported within the respective barrel by a sabot assembly 14. A tail portion 15 extends rearwardly into abutting relationship with the nose of the following projectile 12. For this purpose the rear end of the trailing stem 15 is provided with a recess which snugly accommodates the leading end of the projectile 13. Propellant 16 extends about the trailing stems 15 and when ignited, either electrically or otherwise, acts against the sabots 14 and any laterally extending faces of the respective projectiles to propel them together with their sabots 14 through the barrel towards the muzzle end 20 of the barrel 10. Each barrel 12 flares outwardly at 21 towards the muzzle from a point adjacent the inner end 22 of a concentric stripping sleeve 23 supported within the respective flared end sections 24 by end walls 25. The bore diameter of the sleeves 23 are substantially the same as the external diameter of the projectile heads 13 so that projectile heads may pass directly therethrough and exit the barrel assembly 10 at high velocity. The sleeves 23 taper toward their trailing ends to present a relatively fine annular end to approaching rounds so as to engage between the sabot 14 and the projectile head 13 to strip the sabot 14 from the projectile head 13 as it passes into the sleeve 23. The sabots 14 are diverted about the sleeves 23 by radial expansion thereof or in segments and collect in the annular passage 28 which extends about the sleeve 23. This action causes a change of direction of the sabot portions about the sleeve 23 so that the action will slow and subsequently stop the sabots 14 by impact with the end wall 25 or another sabot already located within the passage 28. This action may be accompanied by a sharp deceleration just prior to impact as gasses are compressed between the leading end of the sabot and the end wall 25. The resultant staged deceleration of the sabots 14 will assist in reducing the recoil action resulting from ignition of the respective propellant charges. Each sabot 14 has an inner annular part 30 engaged on the projectile head 13 through complementary engaged serrations 29 and an associated outer annular part 31 which mates with the inner annular part 30 along a forwardly tapered face 33 such that acceleration of the sabot through the barrel 11 will tend to force the outer part 31 rearwardly along the inner part 30, accompanied by a consequent radial expansion urging the sabot 14 into effective sealing relationship with the barrel 11. A radial flange 32 extends from the back face of the inner part 30 to provide a limit for rearward movement of the outer part 32 and/or a reaction face 35 substantially spanning the barrel 11 and against which the products of combustion of the propellant can react. From the above it will be seen that the beneficial effects of sabots enabling the use of larger quantities of propellant may be achieved without sabot debris causing local effect and without air borne sabot debris providing collision obstacles for subsequently fired rounds. It will of course be realised that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as is herein set forth.

Claims: CLAIMS 1. A barrel assembly incorporating a multiplicity of sabotted projectiles stacked axially within the barrel assembly and a multiplicity of corresponding propellant charges disposed therebetween wherein the barrel assembly includes a barrel having a muzzle and wherein said barrel includes a sabot stripping structure and a sabot receiver arranged whereby sabots are prevented from exiting the muzzle of the barrel and wherein the multiplicity of sabotted projectiles comprise a multiplicity of projectiles and a multiplicity of associated sabots wherein the associated sabots detachably engage the projectiles whereby detonation of a leading propellant urges subsequent sabotted projectiles into sealing engagement with the barrel. 2. A barrel assembly according to claim 1 wherein the multiplicity of projectiles have bullet shaped head portion about which the sabot is disposed and a tail portion that extends rearwardly into abutting relationship with the leading end of the next adjacent trailing projectile whereby the stacked column of sabotted projectiles are positively located in their operative positions in the barrel. 3. A barrel assembly according to claim 1 wherein the sabot detachably engages the projectile whereby it is secured it against forward movement relative to the projectile. 4. A barrel assembly according to claim 3 wherein the sabot is detachably secured to the projectile by a detent for engaging a corresponding recess on the projectile. 5. A barrel assembly according to claim 3 wherein the projectile incorporates a detent for engaging a corresponding recess on the sabot. 6. A barrel assembly according to claim 3 wherein the sabot includes complementary shallow inwardly directed annular ribs on the inner face of the sabot for engagement with shallow outer annular recesses in the projectile. 7. A barrel assembly according to claim 3 wherein the sabot includes an annular concavity in the inner face of the sabot for engagement with a complementary convex outer annular portion of the projectile. 8. A barrel assembly according to claim 3 wherein the sabot detachably engage the projectile through an interference fit. 9. A barrel assembly according to claim 8 wherein the interference fit is a tapered interference fit. 10. A barrel assembly according to claim 1 wherein the associated sabots comprise a pair of complementary continuous or segmented annular portions that engage through opposed tapered land portions whereby the outer annular portion is urged to expand radially upon commencement of movement of the inner annular portion therethrough to sealably engage the barrel wherein the inner annular portion is urged to move through the outer annular portion by the detonation of the propellant charge in front of the sabotted projectile in the array of axially stacked projectiles. 11. A barrel assembly according to claim 10 wherein a transversely extending flange is provided on one annular portion to limit the relative longitudinal movement of the inner portion through the outer portion. 12. A barrel assembly according to claim 11 the flange is a radial outwardly extending flange formed on the trailing end of the inner annular portion. 13. A barrel assembly according to claim 1 wherein the sabot stripping structure includes an inner sleeve portion at or adjacent the muzzle and disposed concentric with the barrel and through which the projectiles pass and about which the sabots pass. 14. A barrel assembly according to claim 13 wherein the inner sleeve is suitably tapered at its stripping end to urge the sabot away from the projectile into an annular barrel portion between the sleeve and the muzzle of the barrel. 15. A barrel assembly according to claim 13 wherein the inner sleeve portion is supported by webs extending between the inner sleeve and the barrel. 16. A barrel assembly according to claim 1 wherein the barrel flares outwardly at the muzzle. 17. A barrel assembly according to claim 1 wherein the stripped sabot is retained in an annular storage portion at the muzzle end of the barrel. 18. A barrel having a muzzle and wherein said barrel includes a sabot stripping structure and a sabot receiver arranged whereby sabots are prevented from exiting the muzzle of the barrel. 19. A barrel according to claim 18 wherein the sabot stripping structure includes an inner sleeve portion at or adjacent the muzzle and disposed concentric with the barrel and through which projectiles pass and about which sabots pass. 20. A barrel according to claim 19 wherein the inner sleeve is suitably tapered at its stripping end to urge the sabot away from the projectile into an annular barrel portion between the sleeve and the muzzle of the barrel. 21. A barrel according to claim 19 wherein the inner sleeve portion is supported by webs extending between the inner sleeve and the barrel. 22. A barrel according to claim 18 wherein the barrel flares outwardly at the muzzle. 23. A barrel according to claim 1 wherein the barrel includes an retainer whereby the stripped sabot is retained in an annular storage portion at the muzzle end of the barrel. 24. A sabotted projectile for stacking axially within a barrel assembly comprising a projectile and a sabot wherein the sabot detachably engages the projectile wherein detonation of a leading propellant in an axially stacked array urges subsequent sabotted projectiles into sealing engagement with the barrel. 25. A sabotted projectile according to claim 24 wherein the projectile has a bullet shaped head portion about which the sabot is disposed and a tail portion that extends rearwardly into abutting relationship with the leading end of the next adjacent trailing projectile whereby a stacked column of sabotted projectiles are positively located in their operative positions in the barrel. 26. A sabotted projectile according to claim 24 wherein the sabot detachably engages the projectile whereby it is secured it against forward movement relative to the projectile. 27. A sabotted projectile according to claim 26 wherein the sabot is detachably secured to the projectile by a detent for engaging a corresponding recess on the projectile. 28. A sabotted projectile according to claim 26 wherein the projectile incorporates a detent for engaging a corresponding recess on the sabot. 29. A sabotted projectile according to claim 26 wherein the sabot includes complementary shallow inwardly directed annular ribs on the inner face of the sabot for engagement with shallow outer annular recesses in the projectile. 30. A sabotted projectile according to claim 26 wherein the sabot includes an annular concavity in the inner face of the sabot for engagement with a complementary convex outer annular portion of the projectile. 31. A sabotted projectile according to claim 26 wherein the sabot detachably engages the projectile through an interference fit. 32. A sabotted projectile according to claim 31 wherein the interference fit is a tapered interference fit. 33. A sabotted projectile according to claim 24 wherein the associated sabots comprise a pair of complementary continuous or segmented annular portions that engage through opposed tapered land portions whereby the outer annular portion is urged to expand radially upon commencement of movement of the inner annular portion therethrough to sealably engage the barrel wherein the inner annular portion is urged to move through the outer annular portion by the detonation of the propellant charge in front of the sabotted projectile in the array of axially stacked projectiles. 34. A sabotted projectile according to claim 33 wherein a transversely extending flange is provided on one annular portion to limit the relative longitudinal movement of the inner portion through the outer portion. 35. A sabotted projectile according to claim 34 the flange is a radial outwardly extending flange formed on the trailing end of the inner annular portion. DATED THIS 9™ DAY OF FEBRUARY 2001 METAL STORM LIMITED BY PIZZEYS PATENT & TRADE MARK ATTORNEYS

Inventors: O'DWYER JAMES MICHAEL, O'DWYER, JAMES, MICHAEL
Applicants: DWYER JAMES MICHAEL O, METAL STORM LTD, METAL STORM LIMITED, O'DWYER, JAMES, MICHAEL
Application year: 2001
Main classification: F41A21
IPC codes: F41A1, F41A21, F42B5, F42B14