Abstract:
Projectiles with sealed propellant are described herein. In one embodiment of the invention, a projectile includes a chamber having a propellant charger, an exit from the chamber for release of propellant gases into a barrel when the propellant is ignited to fire the projectile, and a seal to block the exit which is opened by ignition of the propellant within the chamber but is resistant to ignition of other propellant in the barrel, where the seal is carried from the barrel by the projectile after the ignition. Other methods and apparatuses are also described.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a divisional application of a co-pending U.S. patent application Ser. No. 10/545,206, filed Jun. 16, 2006, which is a national phase application of International Application No. PCT/AU2004/000141, filed Feb. 10, 2004, which claims the priority from Australian Patent Application Nos.: 2003900572 filed Feb. 10, 2003; 2003902103 filed May 2, 2003; and 2003902556 filed May 23, 2003. The disclosures of the above-identified applications are incorporated by reference herein in their entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to projectiles. More particularly, this invention relates to projectiles with sealed propellant.  
       BACKGROUND  
       [0003]     The kinetic energy (KE) of conventional projectiles, for example standard mortar rounds, may be varied by tailoring the amount of propellant that is associated with each projectile before firing. This may require different internal propellant loads produced during manufacture or the use of auxiliary propellant charges, where possible.  
         [0004]     In mortar rounds, the projectiles and auxiliary propellant charges are generally separate from one another before firing. The auxiliary propellant is typically provided in a number of small parcels that may be supplied in different volumes or in the same volume for incremental use. Depending on the range that is required, the mortar operator manually attaches one or more parcels providing the appropriate amount of propellant to the mortar round before insertion into a tube or barrel for firing. This procedure also considerably slows the rate of fire that can be achieved by the weapon and is prone to human error when loading.  
         [0005]     It will be appreciated that a more cost effective, convenient and reliable arrangement for varying the kinetic energy of projectiles is desirable, particularly where a high rate of fire is required. Particularly where the projectile firing weapon is of the type including a plurality of rounds stacked in a barrel for sequential firing and required to be remotely controlled. It would be of further advantage if the construction of individual rounds was substantially homogeneous.  
       SUMMARY OF THE DESCRIPTION  
       [0006]     Projectiles with sealed propellant are described herein. In one embodiment of the invention, a projectile includes a chamber having a propellant charger, an exit from the chamber for release of propellant gases into a barrel when the propellant is ignited to fire the projectile, and a seal to block the exit which is opened by ignition of the propellant within the chamber but is resistant to ignition of other propellant in the barrel, where the seal is carried from the barrel by the projectile after the ignition.  
         [0007]     Other features of the present invention will be apparent from the accompanying drawings and from the detailed description which follows.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     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 embodiments of the invention, wherein:  
         [0009]      FIGS. 1A-1F  show a first embodiment in which a projectile has forward ports for exit of propellant gases;  
         [0010]      FIGS. 2A-2D  show a second embodiment in which a projectile has rearward ports for exit of propellant gases;  
         [0011]      FIGS. 3A, 3B  show an inductive firing system for the projectiles;  
         [0012]      FIG. 4  is a sectional side elevational view of a projectile of another embodiment of the invention, prior to firing;  
         [0013]      FIG. 5  is a sectional side elevational view of the projectile of the embodiment, after firing the third and fourth propellant charges;  
         [0014]      FIG. 6  is a sectional side elevational view of the projectile of the embodiment, after firing the second, third and fourth propellant charges;  
         [0015]      FIG. 7  is a sectional side elevational view of the projectile of the embodiment, after firing all propellant charges;  
         [0016]      FIG. 8  is a sectional end elevational view of the projectile of the embodiment;  
         [0017]      FIG. 9  is a sectional side elevational view of a variation to the projectile of the embodiment;  
         [0018]      FIG. 10  is a sectional side elevational view of a projectile of another embodiment of the present invention, prior to firing;  
         [0019]      FIG. 11  is a sectional end elevational view of the projectile of the embodiment;  
         [0020]      FIG. 12  is a sectional side elevational view of a projectile of a embodiment of the present invention, subsequent to firing all propellant charges;  
         [0021]      FIG. 13  is a sectional side elevational view of a projectile of a embodiment of the present invention;  
         [0022]      FIG. 14  is a sectional end elevational view of the projectile of the embodiment;  
         [0023]      FIGS. 15, 16  and  17  depict a projectile assembly of a embodiment of the present invention; and  
         [0024]      FIGS. 18, 19  and  20  depict a projectile assembly of another embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0025]     In the following description, numerous details are set forth to provide a more thorough explanation of embodiments of the present invention. It will be apparent, however, to one skilled in the art, that embodiments of the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring embodiments of the present invention.  
         [0026]     Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification do not necessarily all refer to the same embodiment.  
         [0027]     Referring to the drawings it will be appreciated that the invention can be implemented in various ways for a variety of projectiles and purposes. The invention may be provided as a single projectile, as a weapon containing projectiles, or as a barrel assembly containing stacked projectiles for insertion in a weapon, for example.  
         [0028]     The embodiments described herein relate to mortar rounds of up to about  60  mm caliber, it will be appreciated that the invention finds application in variety of projectile configurations. In particular, projectile configurations adapted for axial stacking in a barrel assembly and arranged for sequential firing, suitably by electronic means, as disclosed in earlier patent applications originating from either or both of these inventors.  
         [0029]      FIG. 1A  shows a projectile having a body  10  with nose and tail portions  11  and  12  adapted to be stacked in a barrel with other similar projectiles. The projectile typically includes a payload  13  which may be of various kinds such as explosive, flash-bang, smoke-generating or fire retardant for example. Propellant charges  14  are contained by cavities within the projectile and are selectively ignited by respective initiators  15 , preferably inductive elements such as semiconductor bridges (SCBs), although a range of wired or wireless primer systems may be used. The charges are held in their cavities by plugs  16  which may be threaded or glued in place, for example. Ports  17  are provided in the nose portion for exit of the gases produced by combustion of the charges. In this example the ports open forwards and propel a leading adjacent projectile from the barrel. This projectile is in turn propelled by charges in a trailing adjacent projectile or by charges in the base of the barrel. The nose portion is preferably shaped to fit the tail portion of the leading projectile and similarly the tail portion is shaped to fit the nose portion of the trailing projectile. This provides a degree of sealing between the projectiles and may be achieved in various ways.  
         [0030]      FIGS. 1B and 1C  are end views of the projectile in  FIG. 1A  showing the nose and tail portions. There are four propellant charges  14  located symmetrically around the longitudinal axis of the projectile, retained by four plugs  16  and correspondingly provided with four ports  17  for exit of combustion gases. The number and arrangement of the charges may be varied to suit the purpose of the particular projectile. It should be borne in mind however, that the flight characteristics of the projectile may change when the charges are selected and ignited, unless all of the charges are ignited before the projectile is fired from the barrel. The centre of mass of the projectile may shift for example.  
         [0031]      FIG. 1D  shows how two projectiles of this kind may be stacked in a barrel. The nose portion  11  of the trailing projectile fits the tail portion  12  of the leading projectile, and preferably expands the tail portion  12  into a sealing contact with the inside of the barrel. In this example, a convex curved surface of the nose portion matches a concave surface in the tail portion, and the tail portion also includes a rim  18  that contacts the body of the trailing projectile. One or more charges in the trailing projectile are selected and ignited to propel the leading projectile from the barrel with a required kinetic energy. Once the leading projectile has departed any charges remaining in the trailing projectile are ignited to produce a predetermined weight and centre of mass in the trailing projectile, which is now the leading projectile. Each projectile therefore has reasonably standard and predictable characteristics for flight.  
         [0032]      FIGS. 1E and 1F  show how the last projectile in a stack of projectiles of this kind may be fired. Propellant charges  14  may be provided in the base of the barrel as either a separate removable element  19 E, or as a fixed element  19 F of the barrel itself. The charges  14  in each of these figures are contained and ignited in a manner similar to that of the charges in the projectiles. The separate base element  19 E is preferably loaded down the barrel before the projectiles while the fixed base element while charges in the fixed element  19 F may be loaded as individual items from the rear of the barrel. These charges may be selected and fired to provide a predetermined kinetic energy to the last projectile.  10032   FIG. 2A  shows an alternative projectile having a body  20  with nose and tail portions  21  and  22 , adapted to be stacked in a barrel with other similar projectiles if required. The projectile includes a payload  23  in this example. Propellant charges  24  are contained by cavities within the projectile and are selectively ignited by respective initiators  25 , preferably inductive elements such as semiconductor bridges (SCBs), although a range of wired or wireless primer systems may be used. The charges are held in their cavities by plugs  26  which may be threaded or glued in place, for example. Ports  27  are provided in the tail portion for exit of the gases produced by combustion of the charges. In this example the ports open rearwards and propel the respective projectile from the barrel. The nose portion is preferably shaped to fit the tail portion of the leading projectile and similarly the tail portion is shaped to fit the nose portion of the trailing projectile. This provides a degree of sealing between the projectiles and may be achieved in various ways.  
         [0033]      FIGS. 2B and 2C  are end views of the projectile in  FIG. 2A  showing the nose and tail portions. There are four propellant charges  24  located symmetrically around the longitudinal axis of the projectile, retained by four plugs  26  and correspondingly provided with four ports  27  for exit of combustion gases. The number and arrangement of the charges may be varied to suit the purpose of the particular projectile, bearing in mind that the flight characteristics of the projectile may change when the charges are selected and ignited. The weight and centre of mass of the projectile may change for example. On the other hand, the rearward exit ports are less likely to create drag.  
         [0034]      FIG. 2D  shows how two projectiles of this kind may be stacked in a barrel. The nose portion  21  of the trailing projectile fits the tail portion  22  of the leading projectile, and preferably expands the tail portion  22  into a sealing contact with the inside of the barrel. In this example, a convex curved surface of the nose portion matches a concave surface in the tail portion, and the tail portion also includes a rim  28  that contacts the body of the trailing projectile. It will be appreciated that a wide range of shapes and dimensions may be used in any of the projectiles described herein. One or more charges in each projectile are selected and ignited to propel the respective projectile from the barrel with a required kinetic energy. The projectiles generally have less predictable flight characteristics than those of  FIG. 1A .  
         [0035]      FIG. 3A  shows a typical propellant charge  14  or  24  from  FIGS. 1 and 2  in more detail. The charge material  300  is contained by a metal housing  301 , open fully at one end  302  and with a smaller aperture  303  at the other end  304 . A disc  305  of composite material blocks the aperture  303  but is ruptured on ignition of the charge material so that combustion gases can pass through the aperture into a respective exit port. An initiator  306  is threaded or press-fitted into end  302 , based on an SCB igniter in this example. The initiator includes the SCB  307  connected across a coil  308 , both mounted in a fitting  309  of plastic for example. A small amount of pyrotechnic material  310  surrounds the SCB to act as a booster in combustion of the charge material. Many alternative structures could be used for the propellant charges and for the initiator, which could also be introduced directly to cavities in the projectile without need of the housing  301  for example.  
         [0036]     Semiconductor bridges are known devices having the appearance of a microchip with two terminal wires, such as shown in U.S. Pat. No. 4,708,060 and subsequent US patents. If an electric potential is placed across these two wires, the semiconductor bridge releases a small amount of energy, most in the form of heat. The energy released by the SCB may in some cases be insufficient to ignite the propellant charges directly and the initiators may further require a set-up chemical compound (i.e. a compound which is capable of being initiated by an SCB and will, in turn, ignite the charge). SCBs can be designed and arranged such that a current induced between the two terminals can cause energy release. It is considered that the various means of inducing a current in a coil of wire using a magnetic field (induction) are well enough understood by those proficient in the art that such details need not be discussed here, save one example. It is therefore to be taken that all such means of providing a suitable firing current, whether by inducing said current or otherwise, are within the ambit of this invention.  
         [0037]      FIG. 3B  schematically shows an inductive firing system that may be used to launch the projectiles shown in  FIGS. 1 and 2 . A magnetic field suitable to activate an SCB can be induced using a signal transmitting coil  33  wrapped around the barrel  30 , suitably in the vicinity of projectiles  31  therein, i.e. one transmitting or primary coil  33 . 1 ,  33 . 2 , etc. for each projectile  31 . 1 ,  31 . 2 , etc. The current in the primary coils  33  can be selectively turned on or off by a fire control unit (FCU)  39  and thus the resulting current in receiving or secondary coils  35 . 1 ,  35 . 2  can be manipulated in the same fashion. The primary coils may be connected separately to the FCU or in series. The FCU may be operated in various ways to select the kinetic energy and therefore the charges to be ignited for the next projectile to be fired. A manual user could operate a rotatable switch that simply indicates  1 ,  2 ,  3  . . . or all of the charges are to be ignited. The user or an automated firing system determines the kinetic energy required for a particular projectile according to the environment in which the user or the automated system is located.  
         [0038]     In order to fire the charges in a designated projectile (for example projectile  31 . 2 ), the FCU  39  applies firing signal current to the primary coil  33 . 2  wrapped around the barrel  30  for that projectile  35 . 2 . The resultant magnetic field induces a current in the secondary coil  35 . 2 , which is applied to the two terminals of the initiators  32 ,  33 ,  34 . Ignition of one or more propellant charges  36   a,    36   b,    36   c  occurs in response to those initiators arranged to ignite upon receipt of the firing signal.  
         [0039]     SCBs can also be designed such that they will not initiate due to a simple current but only when a particular “type” of current occurs. Indeed, SCB technology now offers the ability to manufacture SCBs that require various and distinct levels of energy of ignition signal to activate the energetic material. Encoders and decoders could also be used in conjunction with SCB technology, if required. Where encoders/decoders and other logic circuits are employed, a signal modulation scheme may comprise any pulse wave modulation (PWM), pulse code modulation (PCM) or pulse amplitude modulation (PAM) scheme, or in any other suitable encoding scheme. This allows the separate, smaller propellant charges  36  to be discretely ignited via the common induction coil pairs  33 ,  35 .  
         [0040]     We now turn to consider the use of variations in current to embed an ignition signal as an example. In order to fire propellant charge  36   a  for the designated (or any particular) projectile  35 . 2  the FCU  39  applies current (with the appropriate modulated variations embedded within it) to the primary coil  33 . 2  associated with that projectile. The resultant current in secondary coil  35 . 2  (induced by the magnetic field) thus varies in intensity in proportion to the variations in current the FCU has applied. The induced current that is delivered to the SCBs thus also varies in proportion with the variations in intensity of the magnetic field. Thus the appropriate SCB  32  in propellant load  36   a  of the projectile  35 . 2  can be delivered the appropriate coded signal and therefore be initiated without the initiation of propellant charges  36   b  or  36   c,  through the use of a single induction coil  33  per projectile.  
         [0041]     It will be appreciated that, upon initiation of a selected propellant charge or charges  36 , the rapid combustion thereof operates to discharge the associated projectile from the barrel  30 . Where only one propellant charge is initiated, eg. centre charge  36   b  by SCB  33 , the kinetic energy imparted to the projectile will be considerably lower than imparted when all three propellant charges  36   a,    36   b,    36   c  are initiated.  
         [0042]     FIGS.  4  to  8  of the drawings depict a projectile  45  of another embodiment of the invention having a projectile body  46  with a cavity  49  wherein a plurality of propellant charges  50  are disposed longitudinally in the projectile. In contrast, the propellant charges of the embodiments discussed above were disposed laterally within the projectile. For reasons of clarity, the initiators and secondary or receiving coils have been omitted from these drawings.  
         [0043]     The projectile  45  is depicted in  FIG. 4  prior to ignition of any of the propellant charges  50 , which charges are separated from one another with the cavity  49  by wall members. The propellant charges  50  are composed of a mouldable material in the present embodiment, whereby the rearmost charge  50 . 4  is exposed through the aperture  58  communicating with the exterior of the projectile adjacent a tail portion of the body  46 . Suitably the wall members are in the form of sealing discs  51  having edge surfaces with profiles arranged to wedge into a shallow inwardly tapered wall of the cavity  47 . Accordingly, the shaped propellant charges and alternating sealing discs may be located into the cavity  49  via the aperture  58  from the tail  48  of the projectile  45 .  
         [0044]     Since the propellant cavity becomes smaller in diameter toward the head portion  47  of the projectile, if the first loaded sealing disc  51  is forced toward the head  47  of the projectile, wedging will occur between the band edge and the tapered interior wall of the cavity  47 , and the disc will retain the forwardmost charge  50 . 1  in place. Accordingly, when a similarly directed force is applied during firing, e.g. the force resulting from combustion of the second propellant charge  50 . 2  being initiated, the sealing disc  51  will further be wedged into place with said interior wall  56 . This “wedge-sealing” action aims to reduce the likelihood of ignition of propellant charge  50 . 2  causing any sympathetic or “blow-by” ignition of propellant charge  50 . 1 .  
         [0045]     Ignition of propellant volume  50 . 1  however will push the adjacent sealing band in the other direction, both unlocking it and forcing it toward the tail  48  of the projectile  45 . The sealing disc  51  will not move far before the edge of the sealing disc loses contact with the cooperating interior wall  56  of the cavity, thereby allowing burning propellant  50 . 1  to reach rearward propellant charge  50 . 2 . The next rearward propellant charge  50 . 2  is thus ignited and the process continues rapidly until propellant volume  50 . 4  is ignited. In summary, the ignition of a particular propellant charge  50  will not ignite a propellant charge that is closer to the nose of the projectile, as explained above.  
         [0046]      FIGS. 5, 6  and  7  show the consequences of igniting a selected propellant charge in the projectile  45 . In  FIG. 5  the third propellant charge  50 . 3  has been ignited resulting in the combustion of charges  50 . 3  and  50 . 4 . In  FIG. 6 , the second propellant charge  50 . 2  has been ignited resulting in the combustion of charges  50 . 2 ,  50 . 3  and  50 . 4 . In  FIG. 7 , the first propellant charge  50 . 1  has been ignited, resulting in the combustion of all propellant charges.  
         [0047]     The aperture includes means for resisting the expulsion of the sealing discs from the cavity, which take the form of a plurality of inwardly radially extending fingers or catch points  57  (as depicted in FIGS.  4  to  8 ) to stop or at least resist the sealing discs  51  from being expelled or otherwise leaving the projectile cavity  49  entirely. There are several small catch points  57  disposed around the periphery of the aperture  58 , as will be apparent from the view of  FIG. 8 . A preferred alternative involves the catch points extending fully across the aperture in the form of a crossbar to ensure that the discs are contained within the projectile. In another form, the wall members or sealing discs may be constructed of a combustible material which has an outer face treated in order to resist combustion, ie. consumption may only be initiated by propellant burning forward of the wall member.  
         [0048]     Since it may or may not be viable for the catch points to be conveniently manufactured as part of the projectile, the catch points  57  may be formed as a separate component  59  that is removably retained in the tail portion  48 ′, such as by cooperating screw threads (not shown), once the cavity  49  has been loaded with propellant charges  50  and respective sealing discs. This component modification of the fourth embodiment is shown in  FIG. 9 .  
         [0049]     In a further modification, the entire cavity portion  49  including the rearward aperture  58  may be formed as a separate component and similarly removably retained in the projectile body  46 . The separate component containing the cavity could alternatively be formed with the lateral arrangement of propellant charges and respective expansion bleed ports as described above.  
         [0050]     In a fifth embodiment of the present invention depicted in  FIGS. 10 and 12  (again omitting the initiators and secondary or receiving coils), a projectile  60  includes wall members  61  that are themselves screw threaded into place via cooperating threads  62  provided on the wall member edges and the interior wall of the propellant cavity  63 , respectively. Furthermore, as shown in  FIG. 10 , the wall members  61  each include sealing plugs  64  that are wedged into place in the wall members in a similar fashion as the sealing discs discussed above.  
         [0051]     The sealing plugs  64  are outfitted with a small T-shaped retaining member  65  that stops or at least resists the plugs from leaving the projectile cavity  63  entirely. It is presently expected that the sealing plugs  64  would need to be manufactured as two pieces (ie. plug and retaining member) and assembled in situ. In a similar fashion to the fourth embodiment discussed above, the T-shaped portion is made up of several small catch points, rather than using the entire ring. However, in this embodiment, the catch points are a plurality of radially outwardly extending fingers  66  of somewhat cruciform configuration. Also as above, this is so that when a T-shaped member  65  hits its respective wall member  61 , it does not close off the propellant charge  67  to the exterior of the projectile  60 , as shown in the enlarged cross-sectional view of the  FIG. 11 .  
         [0052]     It is presently considered that the T-shaped retaining member  65  may only be necessary for the screwed-in wall member  61  closest to the rear of the projectile.  FIG. 12  shows the end result of igniting the forwardmost propellant charge  67 . 1  in this scenario. The individual propellant charges  67  may be ignited using only one induction coil per projectile (as discussed above in relation to  FIGS. 1A and 1B ) with different coded SCBs for each propellant charge  67 . 1 ,  67 . 2 ,  67 . 3 , etc. Accordingly four ( 4 ) different kinds of code responsive SCBs would be required in the presently illustrated example of the fifth embodiment.  
         [0053]     The above embodiments of the invention all entail the use of separate (and generally volumetrically smaller) propellant charges. Typically the operator can elect or an automated fire control system can determine, to burn ¼ of the available propellant, ½, ¾ or all of the propellant available to a particular projectile. However, it is to be understood that propellant volumes need not be divided in this manner, and in fact can be divided in any way desired.  
         [0054]     In  FIGS. 15 and 16  of the drawings there are shown components of a projectile assembly of the type described in the present applicant&#39;s International Patent Application No. PCT/AU02/00932. The earlier invention was concerned with the staged or sequential ignition a plurality of propellant charges associated with each projectile in order to reduce in-barrel pressures whilst maintaining projectile muzzle velocity during firing.  
         [0055]     The applicant has now realized that the present invention may also find a further application as discussed in relation to this sixth embodiment. Here each projectile assembly  80  includes a main projectile body  81  with a head portion  82  and a rearwardly extending tail portion  83  having a tapered skirt  84 , as depicted in  FIG. 15 . The projectile assembly  80  also includes a plurality of propellant cup members  85  which also include a tail portion  86  with tapered skirt  87  extending rearwardly from a transverse wall  88  similarly to the main body  81 , as depicted in  FIG. 16 . When assembled together in a barrel (not shown) and subject to an axial in-barrel load, the wedging action on the tapered skirt portion effectively seals the respective tail portions against the barrel bore, as described in the applicant&#39;s earlier International Applications.  
         [0056]     With reference to  FIG. 17 , it will be seen that the assembled main projectile  81  and cooperating cup members  85 . 1 ,  85 . 2  effectively from a cavity that is divided by wall members formed by transverse walls  88  of the propellant cups. Thus by provision of coded firing signals to the initiators  90  disposed with the respective propellant charges  89 , one, two or all three charges may be simultaneously fired to achieve a desired muzzle velocity.  
         [0057]     A further embodiment of the invention is depicted in  FIGS. 18, 19  and  20 , wherein the main projectile body  91  is of the type including a head portion  92  with rearwardly extending central spine  93  and a band or collar  94  disposed on the head portion  92  of the projectile body  91 , wherein the collar and head portion include complementary tapered surfaces  95 ,  96 . An auxiliary projectile body  97  also includes a central spine  98  and a similarly configured collar member  99 . In both cases, the collar members are arranged to provide an operative seal with the bore of a barrel (not shown).  
         [0058]     With particular reference to  FIG. 20 , it will be appreciated that individual propellant charges  101 ,  102 ,  103 ,  104 ,  105  and  106  may be selectively simultaneously ignited by receipt of firing signals by respective initiators  111 ,  112 ,  113 ,  114 ,  115  and  116 . In the present embodiment, each initiator is integrated with a receiving means that can receive the firing signals directly from a signal transmitting coil disposed in the barrel (not shown), thus obviating the requirement for secondary receiving coils.  
         [0059]     Further, the embodiment illustrates how different propellant charge separating means may be employed together in a projectile assembly, in that a given pair of charges  103 - 104  is separated from other pairs  101 - 102  and  105 - 106  by transverse walls of the auxiliary projectiles  97 . 1 ,  97 . 2 , whilst individual charges within the pair may be separated by respective enclosures in the form of non-metallic bags  121 ,  122 ,  123 ,  124 ,  125  and  126 .  
         [0060]     In the embodiments discussed above, it will be appreciated that any propellant charges remaining in the barrel after firing a particular projectile may be cleared from the barrel by separate initiation, prior to firing the next projectile in the stack of projectiles.  
         [0061]     Furthermore, it is envisaged that the propellant division and selective initiation arrangement of the present invention may be used within many of the present applicant&#39;s other earlier projectile designs and barrel assembly configurations. Put more simply, there are existing designs and configurations not mentioned here that could use the method outlined above of separate smaller propellant loads and coded SCBs (or other ignition method) to achieve an electronically selectable range variable projectile.  
         [0062]     For example in the barrel assembly  70  of  FIG. 13 , with projectiles  71  axially stacked with a barrel  72  as illustrated in sectional side elevation, the propellant charge  73  could be split into four loads  73 . 1 ,  73 . 2 ,  73 . 3 ,  73 . 4 , using bags each containing a respective initiator  74 ,  75 ,  76 ,  77 , as shown in  FIG. 14 .  
         [0063]     With the addition of different coded SCBs to each bag and an induction coil pair (not shown) for each projectile we have a system similar to that of above. It is to be taken that the present invention is applicable to alternative configurations of projectile and barrel assemblies (not explicitly mentioned here), including but not necessarily limited to those of the applicant, which are to be considered within the ambit of this patent application.  
         [0064]     It is to be understood that the above embodiments have been provided only by way of exemplification of this invention, and that further modifications and improvements thereto, as would be apparent to persons skilled in the relevant art, are deemed to fall within the broad scope and ambit of the present invention described above.