Patent Abstract:
A barrel assembly ( 10 ) for munitions and firearms, said barrel assembly including a barrel ( 12 ) having a muzzle with a plurality of tubular rounds ( 11 ) stacked axially within the barrel together with discrete selectively ignitable propellant charges ( 15 ). The rounds ( 11 ) suitably include tubular bodies ( 13   a,    13   b,    13   c,    13   d ) and closure means ( 14   a,    14   b,    14   c,    14   d ) interposed between the tubular rounds for effecting both an operative barrel closure between the tubular rounds ( 11 ) and operative sealing engagement with the barrel ( 12 ). The propellant charges ( 15 ) are contained within each round ( 11 ) and selectively ignitable ( 15   a ) for propelling an adjacent leading round ( 13   a ) and associated closure means ( 14   a ) through the muzzle of the barrel.

Full Description:
TECHNICAL FIELD  
         [0001]    The invention relates to munitions and firearms. This invention has particular, but not exclusive, application to a barrel assembly having a plurality of rounds stacked axially within a barrel together with discrete selectively ignitable propellant charges for propelling the rounds sequentially through the muzzle of the barrel. Such barrel assemblies will be referred to hereinafter as “of the type described”.  
         BACKGROUND ART  
         [0002]    This invention concerns barrel assemblies for munitions and firearms, particularly of the type described, such as illustrated in earlier International Patent Applications Nos. PCT/AU94/00124 and PCT/AU96/00459 filed by the present inventor.  
           [0003]    Whilst tubular rounds are known in certain limited applications such as supersonic projectiles, the applicant is unaware of any tubular rounds suitable for stacking within a barrel with selectively ignitable propellant charges, and particularly no tubular rounds suited to barrel assemblies of the type described.  
         DISCLOSURE OF INVENTION  
         [0004]    It is desirable to provide barrel assemblies for electronically controlled munitions and firearms, particularly of the type described, that are adapted to firing tubular type rounds, and to provide tubular rounds for that purpose.  
           [0005]    According to one aspect this invention provides a barrel assembly of the type described including:  
           [0006]    a barrel having a muzzle;  
           [0007]    a plurality of tubular rounds stacked axially within the barrel and arranged for operative sealing engagement with the barrel;  
           [0008]    closure means interposed between the tubular rounds for effecting both an operative barrel closure between the tubular rounds; and  
           [0009]    a selectively ignitable propellant charge within each round and ignitable for propelling an adjacent leading round and associated closure means through the muzzle of the barrel.  
           [0010]    Preferably the tubular rounds are stacked in abutting relationship, although they could be spaced apart by the propellant. It is also preferred that each round includes a tubular body having a closure means associated with at least its trailing end.  
           [0011]    The closure means may also act to close the leading end of the trailing round. Alternatively, separate closure means could be used for the leading and trailing ends of each round provide that the closure for the leading end is made inoperative upon ignition of the charge therein to enable the combustion effects to propel the leading round from the barrel.  
           [0012]    The closure means may be arranged to discard from the tubular body or it may be fixed to the leading tubular body. The tubular rounds may be configured to have desired flight characteristics by their aerodynamic form. The form of the inner face of the tubular body, when used with a discarding closure means, may act to maintain axial alignment of the round with the flight path. Alternatively the tubular body may be weighted whereby one end is heavier than the other end.  
           [0013]    The closure means is suitably a closure wall member sandwiched between adjacent tubular body portions. Each closure wall member may extend to and engages sealably with the barrel. Alternatively the tubular rounds may have complementary outer end wall portions which abut or lie closely adjacent one another, with the closure wall member being sandwiched between inner end wall portions.  
           [0014]    In the former arrangement, the closure wall member may be sandwiched between end faces of adjacent tubular rounds. The closure wall member may be of a form which does not deform under operational conditions. Alternatively, the peripheral portion of the closure wall member may be formed so as to spread outwardly between the adjacent tubular rounds into operative sealing engagement with the barrel by axial compression applied by the end faces. For low pressure applications, such deformation for effecting a tight sealing engagement with the barrel should not be necessary.  
           [0015]    The end faces of adjacent tubular rounds may extend radially of the barrel or the end faces of adjacent tubular rounds may be formed to engage with respective complementary wedging surfaces on the peripheral portion of the sandwiched closure wall member.  
           [0016]    The tubular bodies of adjacent rounds may overlap one another to provide a telescoped engagement between adjacent rounds. For this purpose the rounds may include outer end wall portions which overlap inner end wall portions of the adjacent round and the closure wall members may be sandwiched between inner complementary end wall faces of the telescoped rounds.  
           [0017]    If desired the telescoped portions of adjacent rounds may include a thin walled portion which may expand outwardly into sealing engagement with either the adjacent telescoped round portion so as to prevent escape of propellant into the barrel or blow by into the adjacent propellant charge. Alternatively the outward expansion may be of the outer telescoped portion so as to enhance the sealing engagement of the round being fired and the barrel.  
           [0018]    Each sandwiched closure wall member may also be arranged to react to propellant charge pressure against its leading face to seal against the end face of the trailing round to prevent blow-by ignition of the charge contained in the adjacent trailing round. Such reactive sealing may also occur between abutting end face portions of the rounds and/or between the leading round and the closure wall member.  
           [0019]    The ignition of the propellant charges may be such as is described in my earlier International applications. For this purpose each selectively ignitable propellant charge may include an electrically actuated primer connected to a pair of spaced annular contacts extending about the round and contacting respective electrical contacts protruding through the barrel and suitably associated with electronic control means.  
           [0020]    The closure means may be integral with the rounds and may include wall segments which may move, or a wall which may expand, forwardly from a closed attitude to an open attitude and substantially barrel conforming attitude. When in the closed attitude the wall segments may react to ignition of a leading propellant charge to maintain or enhance the closing effect of the closure means.  
           [0021]    Suitably each round with its propellant charge is prepared prior to loading into the barrel but if desired the barrel may be loaded by sequentially loading a round tubular body having on open leading end, propellant charge followed by closure of the open end, either as a separate operation or as a result of placing the next round tubular body into its located position.  
           [0022]    In another aspect, the invention resides in a round for firing from the barrel assembly of a munition or firearm, said round including:  
           [0023]    an open ended tubular body adapted for loading into a barrel of the barrel assembly and for operative sealing engagement with the barrel;  
           [0024]    a closure wall member adapted to be interposed between said tubular body and the tubular body of an adjacent round for effecting an operative barrel closure between rounds; and  
           [0025]    a selectively ignitable propellant charge within the tubular body of the adjacent round, which propellant charge is ignitable for propelling the tubular body of said round through the muzzle of the barrel. 
       
    
    
     BRIEF DETAILS OF THE DRAWINGS  
       [0026]    In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate typical embodiments of this invention and wherein:  
         [0027]    [0027]FIGS. 1A to  1 D diagrammatically illustrate, in section, one form of the invention and its mode of operation;  
         [0028]    [0028]FIGS. 2A to  2 D diagrammatically illustrate, in section, a further embodiment of the invention and its mode of operation;  
         [0029]    [0029]FIG. 3 is a perspective view illustrating one round of the embodiment illustrated in FIGS. 2A to  2 D;  
         [0030]    [0030]FIG. 4 diagrammatically illustrates, in section, another form of the invention; and  
         [0031]    [0031]FIG. 5 diagrammatically illustrates, in section, yet another form of the invention. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0032]    In the embodiment illustrated in FIGS. 1A to  1 D, the barrel assembly  10  has a plurality of rounds  11  stacked in axial abutting relationship within the barrel  12  and which are adapted to be fired electrically or otherwise in sequence, such as is illustrated in the inventor&#39;s earlier International applications or as is otherwise known in the art.  
         [0033]    Each round  11  comprises a tubular body  13  associated with a barrel closure member  14  disposed between and separating adjacent tubular bodies  13   a,    13   b,    13   c  and  13   d  from one another, and with a propellant charge  15  arranged behind a closure member  14 . The propellant charge  15   a  is, for example, supported within a trailing tubular body  13   b  between respective barrel closure members  14   a  and  14   b.  In the embodiment a further propellant charge  15   d  is contained in a rear extension  16  of the barrel assembly  10  for propelling the rearmost tubular body  13   d.    
         [0034]    It will be seen in FIG. 1A that the leading annular end  18  of each body  13  extends inwardly and rearwardly to form a part conical end face  19 . The part conical end face co-operates with a complementary part conical face  22  formed about the outer trailing peripheral portion of the barrel closure member  14 , as shown in FIG. 1B. A further complementary part conical leading face  23  is formed about the outer edge of the closure member  14 , as shown in FIG. 1C. The further complementary part conical leading face  23  is associated with a return face  24  so as to provide a recess  25  which receives the complementary shaped trailing end wall  26  of each tubular body  13 .  
         [0035]    It will be seen that the end walls  26  return inwardly whereas the remainder of the tubular body  13  is of constant tubular section, although it could be formed to provide a venturi shape through the body  13  if desired.  
         [0036]    The return wall portion  26  is captured by the closure member  24  during firing of the leading body  13  from the barrel as illustrated in FIG. 1B. As depicted in FIG. 1C the closure member  14  may be discarded from the tubular body  13  during flight, such as the result of rotation of the body  13  due to rifling provided in the barrel  12  or it may stay with the body  13  during flight as depicted in FIG. 1D. For this purpose, the closure member  14  could be secured to the body  13  by screwing, pinning, gluing, swaging or otherwise as required.  
         [0037]    In use, the barrel assembly  10  is stacked with rounds  11  wherein an empty tubular body  13   a  is the leading projectile. When the leading propellant charge  15   a  is ignited in the next adjacent body  13   b,  the resultant gas pressure will act upon both the leading and trailing end closure members  14   a,    14   b  enclosing the ignited propellant charge. The action of the gas pressure causes the leading closure member  14   a  to be propelled from the barrel  12  together with the leading body  13   a.  At the same time the gas pressures will force the trailing closure member  14   b  into axial compression with the trailing body  13   b,  resulting in radial expansion of the part conical end face  19  of the trailing body.  
         [0038]    This arrangement will wedge the leading annular end  18  of the trailing body  13   b  into sealing engagement with the barrel  12  and wedge the closure member  14   b  into sealing engagement with the part conical end face  19 , ensuring there is no leaking of combustion gasses into the propellant of the next trailing charge  15   b.  Thereafter, the empty body  13   b  as shown in FIG. 1B may be propelled from the barrel assembly  10  by ignition of the propellant  15   b  in the next trailing body  13   c.    
         [0039]    In the embodiment of the barrel assembly illustrated in FIGS. 2A to  2 D, each round  30  has a tubular body portion  31  provided with outwardly converging wall segments  33  which abut or overlap to form respective closures for the tubular body  31 . These segments  33  provide a central land portion  35  which mutually abut when the rounds  30  are disposed along the length of a barrel  36 .  
         [0040]    The preferred form of wall segments  33  is an opposing pair of segments as illustrated in FIG. 3, disposed between body extensions  38  having end walls  39  which abut when disposed in the barrel  36 .  
         [0041]    The leading segments  33  open to lie alongside the barrel  36  upon ignition of the propellant  37  contained within the round  30 . Propellant ignition also propels the leading round  30 , shown partially in FIG. 2A. This action provides the next leading round  30  with a substantially tubular body  31  in the barrel, which body is closed only at its rear end by the trailing closure segments  33  which diverge rearwardly to provide a land portion  35 , as shown in FIG. 2B. The land portion  35  abuts the land portion  35  formed at the front of the forwardly diverging segments  33  of the next adjacent trailing round  30 .  
         [0042]    When the propellant  37  in that next adjacent trailing found  30  is ignited, its leading segments  33  will open to place the pressure of the combustion gasses into contact with the trailing faces of the segments  33  at the trailing end of the leading body  31  and thus propel that body from the barrel  36 . In this action, the next body is made ready for firing.  
         [0043]    The segments could alternatively be a plurality of substantially triangular segments having their bases disposed about the periphery of the body  31  and extending inwardly to form a pyramid shaped closure.  
         [0044]    If desired, the trailing closure segments  33  may be coupled to the tubular body  31  by hinge means  32 , which segments open upon exiting the barrel due to air pressure passing through the tubular body  31 , as illustrated in FIG. 2D. If desired, these segments  33  may be provided with flights or other projections to stabilise the flight of the body  31  or make it spin as required.  
         [0045]    It will be seen from the above that the high pressure resulting from propellant burn which propels the leading body  31  acts on the rear section of the trailing round, pressing it against the leading edge of the following round, and sealing against undesired blow-by ignition of the propellant in that following round, thus ensuring consistent operation of the firearm at a desired firing rate.  
         [0046]    In operation barrel closure members  14  may be the free floating and behave as a discarding section, separated by the rotation of the tubular round if fired from a rifled barrel, or separated by air pressure during flight. With the section discarded the round would have improved aerodynamic performance for relatively long range engagements, such as need when fired from an aircraft or when used to engage incoming missiles in such areas as ship self defence.  
         [0047]    However, in certain applications there may be-advantage in fixing the closure members  14  to the tubular body  31 . For example, the closed rounds may be fired from multiple barrels against a buried land mine. Such a round would then act to scoop earth into the body  31  and carry it away from the mine location. That effect would be into addition to the usual disturbance of earth due to the kinetic impact of the round on the ground. Firing multiple rounds from multiple barrels thus has the potential to provide improved means of exposing and/or neutralizing buried land mines.  
         [0048]    The rounds make contact with each other while stacked in a barrel, and are positively located in their intended position. In effect, the rounds utilize a cartridge case which also doubles as the projectile itself.  
         [0049]    In the barrel assembly  40  illustrated in FIG. 4, the barrel  41  is shown cutaway at its leading end or muzzle so that only the two rearmost rounds  42  and  43  are illustrated, a leading round (not shown) having been recently fired from the barrel. It will be seen that in this embodiment the rounds  42  and  43  are telescoped, with the outer leading end portion  44  of the trailing round  43  extending about the inner trailing end portion  45  of the intermediate round  42 .  
         [0050]    All end face portions are part conical with the respective complementary outer end face portions  46  and  47  terminating adjacent one another, and the inner end face portions  48  and  49  terminating in spaced apart relation with one another and in abutting relationship with the closure wall member  50 . The closure wall member includes a peripheral portion  52  also having a part conical end face  54 . In this embodiment the telescoped wall portions  44  and  45  are relatively long and are formed as a close fit, one within the other.  
         [0051]    In use during discharge of the leading round (not shown), propellant pressure acts against the closure wall member  50  of the intermediate round  42  which contains the ignited propellant. This urges the end face  54  of the wall member  50  against the complementary inner end face portion  49  of the trailing round  43 . During exit of the leading round, pressure thus acts on the leading ends  47 ,  49  of the trailing round  43  and forces the intermediate projectile  42  outward and rearward to wedge the trailing face  46  into the leading outer face  47  effecting a seal therebetween. The outward pressure also expands the leading end  51  of the leading outer end portion  44  of the trailing round  43  into engagement with the barrel  41 .  
         [0052]    The inner faces  48 ,  49  also wedge into sealing engagement with the peripheral portion  52  of the closure wall member  50 , preventing blow by ignition of the propellant for the trailing round  43 . Furthermore, the propellant pressure will tend to expand the inner trailing end portion  45  of the intermediate round  42  into tight engagement with the outer leading end portion  44  of the trailing round  43  so as minimise leakage to the barrel  41 .  
         [0053]    As illustrated a primer  55  is located within each selectively ignitable propellant charge  56  and connected to positive and negative slip ring type contacts  57 ,  58  spaced along the outer periphery of the rounds  42 ,  43 . The barrel  41  is provided with correspondingly located spring contacts  53 ,  59  protruding into the barrel for effecting a contact with the respective contact rings  57 ,  58 .  
         [0054]    Suitable electronic controls are provided for actuating the primer and igniting the propellant charges  56 . These peripheral contacts  57 ,  58  are suitably utilised on all the illustrated rounds such as is shown in FIG. 3.  
         [0055]    The barrel assembly  60  illustrated in FIG. 5 is similar to the embodiment illustrated in FIG. 4, the difference being reversal of the rounds  61  and the annular skirt portion  63  provided in the barrel  64 . That is in the FIG. 4 embodiment, the rounds  42 ,  43  have an inner wall which reduces rearwardly whereas the inner wall  62  of the rounds  61  is of constant diameter throughout the majority of its length and then expands outwardly. It is believed that this arrangement will provide a more aerodynamic configuration but less effective sealing than the embodiment of FIG. 4.  
       Industrial Application  
       [0056]    The barrel assembly and tubular rounds of this invention could be utilised in small arms but it is envisaged that they would be more suited to rounds of 20 mm diameter and above. It will be seen that each barrel closure may cooperate with the leading annular end of the adjacent tubular round, either by forcing the annular end outwardly into contact with the bore of the barrel and wedge a barrel closure into sealing engagement with the barrel or the leading annular end, or by causing the closure member to wedge into close sealing contact with the part-conical inner end of the tubular round and without significant expansion of that leading end into engagement with the barrel.  
         [0057]    This wedging may be achieved by maintaining the wedging angles relatively steep, by providing a stop on the leading end which stops rearward movement of the closure at a point at which sealing between the closure and tubular round is effected but prior to radial expansion of the leading end of the tubular round occurring. Alternatively the leading end may be formed sufficiently robust to resist outward splaying under the influence of the wedging action created by the propulsion force from a leading round. Such a sealing action is more suited to low pressure, low muzzle velocity applications.  
         [0058]    While illustrated as being stacked rounds supplied in situ in a barrel, the rounds may also be supplied individually to a weapon from an external magazine by conventional means. For this purpose each round may include the closure wall suitably fixed to the trailing end of the round and a wad closure or the like for securing the propellant in the round.  
         [0059]    The barrel assemblies of this invention which utilise open tubular rounds may also be useful for firing from underwater locations such as from ships, submarines or as concealed land based surface piercing defence installations. For example submarines may utilise such barrel assemblies for self-defence, for underwater mine destruction or anti-torpedo or missile activity.  
         [0060]    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 set forth in the following claims.

Technology Classification (CPC): 5