Patent Publication Number: US-6910423-B2

Title: Kinetic energy rod warhead with lower deployment angles

Description:
RELATED APPLICATIONS 
   This application is a Continuation-in-Part application of U.S. patent application Ser. No. 09/938,022, filed Aug. 23, 2001 now U.S. Pat. No. 6,598,534. 

   FIELD OF THE INVENTION 
   This invention relates to improvements in kinetic energy rod warheads. 
   BACKGROUND OF THE INVENTION 
   Destroying missiles, aircraft, re-entry vehicles and other targets falls into three primary classifications: “hit-to-kill” vehicles, blast fragmentation warheads, and kinetic energy rod warheads. “Hit-to-kill” vehicles are typically launched into a position proximate a re-entry vehicle or other target via a missile such as the Patriot, THAAD or a standard Block IV missile. The kill vehicle is navigable and designed to strike the re-entry vehicle to render it inoperable. Countermeasures, however, can be used to avoid the “hit-to-kill” vehicle. Moreover, biological warfare bomblets and chemical warfare submunition payloads are carried by some threats and one or more of these bomblets or chemical submunition payloads can survive and cause heavy casualties even if the “hit-to-kill” vehicle accurately strikes the target. 
   Blast fragmentation type warheads are designed to be carried by existing missiles. Blast fragmentation type warheads, unlike “hit-to-kill” vehicles, are not navigable. Instead, when the missile carrier reaches a position close to an enemy missile or other target, a pre-made band of metal on the warhead is detonated and the pieces of metal are accelerated with high velocity and strike the target. The fragments, however, are not always effective at destroying the target and, again, biological bomblets and/or chemical submunition payloads survive and cause heavy casualties. 
   The textbook by the inventor hereof, R. Lloyd, “Conventional Warhead Systems Physics and Engineering Design,” Progress in Astronautics and Aeronautics (AIAA) Book Series, Vol. 179, ISBN 1-56347-255-4, 1998, incorporated herein by this reference, provides additional details concerning “hit-to-kill” vehicles and blast fragmentation type warheads. Chapter 5 of that textbook, proposes a kinetic energy rod warhead. 
   The two primary advantages of a kinetic energy rod warheads is that 1) it does not rely on precise navigation as is the case with “hit-to-kill” vehicles and 2) it provides better penetration then blast fragmentation type warheads. 
   To date, however, kinetic energy rod warheads have not been widely accepted nor have they yet been deployed or fully designed. The primary components associated with a theoretical kinetic energy rod warhead is a hull, a projectile core or bay in the hull including a number of individual lengthy cylindrical projectiles, and an explosive charge in the hull about the projectile bay with sympthic explosive shields. When the explosive charge is detonated, the projectiles are deployed. 
   The cylindrical shaped projectiles, however, may tend to break and/or tumble in their deployment. Still other projectiles may approach the target at such a high oblique angle that they do not effectively penetrate the target. See “Aligned Rod Lethality Enhanced Concept for Kill Vehicles,” R. Lloyd “Aligned Rod Lethality Enhancement Concept For Kill Vehicles” 10 th  AIAA/BMDD TECHNOLOGY CONF., Jul. 23-26, Williamsburg, Va., 2001 incorporated herein by this reference. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of this invention to provide an improved kinetic energy rod warhead. 
   It is a further object of this invention to provide a higher lethality kinetic energy rod warhead. 
   It is a further object of this invention to provide a kinetic energy rod warhead with structure therein which aligns the projectiles when they are deployed. 
   It is a further object of this invention to provide such a kinetic energy rod warhead which is capable of selectively directing the projectiles at a target. 
   It is a further object of this invention to provide such a kinetic energy rod warhead which prevents the projectiles from breaking when they are deployed. 
   It is a further object of this invention to provide such a kinetic energy rod warhead which prevents the projectiles from tumbling when they are deployed. 
   It is a further object of this invention to provide such a kinetic energy rod warhead which insures the projectiles approach the target at a better penetration angle. 
   It is a further object of this invention to provide such a kinetic energy rod warhead which can be deployed as part of a missile or as part of a “hit-to-kill” vehicle. 
   It is a further object of this invention to provide such a kinetic energy rod warhead with projectile shapes which have a better chance of penetrating a target. 
   It is a further object of this invention to provide such a kinetic energy rod warhead with projectile shapes which can be packed more densely. 
   It is a further object of this invention to provide such a kinetic energy rod warhead which has a better chance of destroying all of the bomblets and chemical submunition payloads of a target to thereby better prevent casualties. 
   The invention results from the realization that a higher lethality kinetic energy rod warhead can be effected by the inclusion of means for reducing the angle of deployment of the individual projectiles when they are deployed. 
   This invention features a kinetic energy rod warhead comprising a projectile core including a plurality of individual projectiles, an explosive charge about the core, at least one detonator for the explosive charge, and means for reducing the deployment angles of the projectiles when the detonator detonates the explosive charge. 
   In one embodiment, the structure for reducing the deployment angles includes a buffer between the explosive charge and the core. In one example, the buffer is a poly foam material and the buffer extends beyond the core. The means for reducing may also be or include multiple spaced detonators for the explosive charge to generate a flatter shock front. The detonators, in one embodiment, are located proximate the buffer. 
   Typically, an end plate is located on each side of the projectile core. Each end plate maybe made of steel or aluminum. The means for reducing may include an absorbing layer between each end plate and the core. In one example, the absorbing layer is made of aluminum. Another structure for reducing the deployment angles includes a buffer between the absorbing layer and the core. In one example, the buffer is a layer of poly foam. Still another structure for reducing the deployment angles includes a momentum trap on each end plate. In one example, the momentum trap is a thin layer of glass applied to the end plates. 
   Typically, the core includes a plurality of bays of projectiles. In this embodiment, the means for reducing may include a buffer disk between each bay. In one example, there are three bays of projectiles. Additional means for reducing includes selected projectiles which extend continuously through all the bays. In one example, selected projectiles extend continuously through each bay with frangible portions located at the intersections between two adjacent bays. 
   Typically, the core includes a binding wrap around a projectiles. And, in one example, the projectile core includes an encapsulant sealing the projectiles together. In one example, the encapsulant includes grease on each projectile and glass in the spaces between projectiles. 
   Typically, the explosive charge is divided into sections and there are shields between each explosive charge section. In one example, the shields are made of composite material such as steel sandwiched between Lexan layers. In the preferred embodiment, each explosive charge section is wedged-shaped having a proximal surface abutting the projectile core and a distal surface. Typically, the distal surface is tapered to reduce weight. 
   In one example, the projectiles have a hexagon shape and are made of tungsten. In other embodiments, the projectiles have a cylindrical cross section, a non-cylindrical cross section, a star-shaped cross section, or a cruciform cross section. The projectiles may have flat ends, a non-flat nose, a pointed nose, or a wedge shaped nose. 
   Further included may be means for aligning the individual projectiles when the explosive charge deploys the projectiles. In one embodiment, the means for aligning includes a plurality of detonators space along the explosive charge configured to prevent sweeping shock waves at the interface of the projectile core and the explosive charge to prevent tumblings of the projectiles. In another embodiment, the means for aligning includes a body in the core with orifices therein, the projectiles disposed in the orifices of the body. In one example, the body is made of low density material. In another embodiment, the means for aligning includes a flux compression generator which generates a magnetic alignment field to align the projectiles. In one example, there are two flux compression generators, one on each end of the projectile core and each flux compression generator includes a magnetic core element, a number of coils about the magnetic core element, and an explosive for the imploding the magnetic core element. 
   This invention also features a kinetic energy rod warhead with lower deployment angles comprising a projectile core including a plurality of bays of individual projectiles, an explosive charge about the core divided into sections, shields between each explosive charge section, at least one detonator associated with selected explosive charge sections for aiming the projectiles in a predetermine primary firing direction, an end plate on each side of the projectile core, and a buffer between the explosive charge and a core to reduce the deployment angles of the projectiles when the detonators detonate the explosive charge. 
   A kinetic energy rod warhead in accordance with this invention may include a projectile core including a plurality of bays of individual projectiles, an explosive charge about the core divided into sections, shields between each explosive charge section, a plurality of spaced detonators associated with selected explosive charge sections, an end plate on each end of the projectile core, a buffer between the explosive charge and the core extending beyond the core, and a buffer between each projectile bay. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which: 
       FIG. 1  is schematic view showing the typical deployment of a “hit-to-kill” vehicle in accordance with the prior art; 
       FIG. 2  is schematic view showing the typical deployment of a prior art blast fragmentation type warhead; 
       FIG. 3  is schematic view showing the deployment of a kinetic energy rod warhead system incorporated with a “hit-to-kill” vehicle in accordance with the subject invention; 
       FIG. 4  is schematic view showing the deployment of a kinetic energy rod warhead as a replacement for a blast fragmentation type warhead in accordance with the subject invention; 
       FIG. 5  is a more detailed view showing the deployment of the projectiles of a kinetic energy rod warhead at a target in accordance with the subject invention; 
       FIG. 6  is three-dimensional partial cut-away view of one embodiment of the kinetic energy rod warhead system of the subject invention; 
       FIG. 7  is schematic cross-sectional view showing a tumbling projectile in accordance with prior kinetic energy rod warhead designs; 
       FIG. 8  is another schematic cross-sectional view showing how the use of multiple detonators aligns the projectiles to prevent tumbling thereof in accordance with the subject invention; 
       FIG. 9  is an exploded schematic three-dimensional view showing the use of a kinetic energy rod warhead core body used to align the projectiles in accordance with the subject invention; 
       FIGS. 10 and 11  are schematic cut-away views showing the use of flux compression generators used to align the projectiles of the kinetic energy rod warhead in accordance with the subject invention; 
       FIGS. 12-15  are schematic three-dimensional views showing how the projectiles of the kinetic energy rod warhead of the subject invention are aimed in a particular direction in accordance with the subject invention, 
       FIG. 16  is a three dimensional schematic view showing another embodiment of the kinetic energy rod warhead of the subject invention; 
       FIGS. 17-23  are three-dimensional views showing different projectile shapes useful in the kinetic energy rod warhead of the subject invention; 
       FIG. 24  is a end view showing a number of star-shaped projectiles in accordance with the subject invention and the higher packing density achieved by the use thereof; 
       FIG. 25  is another schematic three-dimensional partially cut-away view of another embodiment of the kinetic energy rod warhead system of the subject invention wherein there are a number of projectile bays; 
       FIG. 26  is another three-dimensional schematic view showing an embodiment of the kinetic energy rod warhead system of this invention wherein the explosive core is wedge shaped to provide a uniform projectile spray pattern in accordance with the subject invention; 
       FIG. 27  is a cross sectional view showing a wedge shaped explosive core and bays of projectiles adjacent it for the kinetic energy rod warhead system shown in  FIG. 26 ; 
       FIG. 28  is a schematic depiction of a test version of a kinetic energy rod warhead in accordance with the subject invention with three separate rod bays; 
       FIG. 29  is a schematic depiction of the warhead of  FIG. 28  after the explosive charge sections are added; 
       FIG. 30  is a schematic depiction of the rod warhead shown in  FIGS. 28 and 29  after the addition of the top end plate; 
       FIG. 31  is a schematic view of the kinetic energy rod warhead of  FIG. 30  just before a test firing; 
       FIG. 32  is a schematic view showing the results of the impact of the individual rods after the test firing of the warhead showing in  FIG. 31 ; 
       FIG. 33  is a schematic view showing a variety of individual penetrator rods after the test firing; 
       FIG. 34  is a schematic cross sectional view of a kinetic energy warhead with lower deployment angles in accordance with the subject invention; 
       FIG. 35  is an exploded view showing the use of buffer disks between the individual bays of projectiles in order to lower the deployment angles of the rods in accordance with the subject invention; 
       FIG. 36  is a schematic depiction showing the use of a glass filler around individual penetrators in order to lower the deployment angles in accordance with the subject invention; and 
       FIG. 37  is a schematic three-dimensional view showing a different type of projectile in accordance with the subject invention including two fragable portions. 
   

   DISCLOSURE OF THE PREFERRED EMBODIMENT 
   As discussed in the Background section above, “hit-to-kill” vehicles are typically launched into a position proximate a re-entry vehicle  10 ,  FIG. 1  or other target via a missile  12 . “Hit-to-kill” vehicle  14  is navigable and designed to strike re-entry vehicle  10  to render it inoperable. Countermeasures, however, can be used to avoid the kill vehicle. Vector  16  shows kill vehicle  14  missing re-entry vehicle  10 . Moreover, biological bomblets and chemical submunition payloads  18  are carried by some threats and one or more of these bomblets or chemical submunition payloads  18  can survive, as shown at  20 , and cause heavy casualties even if kill vehicle  14  does accurately strike target  10 . 
   Turning to  FIG. 2 , blast fragmentation type warhead  32  is designed to be carried by missile  30 . When the missile reaches a position close to an enemy re-entry vehicle (RV), missile, or other target  36 , a pre-made band of metal or fragments on the warhead is detonated and the pieces of metal  34  strike target  36 . The fragments, however, are not always effective at destroying the submunition target and, again, biological bomblets and/or chemical submunition payloads can survive and cause heavy casualties. 
   The textbook by the inventor hereof, R. Lloyd, “Conventional Warhead Systems Physics and Engineering Design,” Progress in Astronautics and Aeronautics (AIAA) Book Series, Vol. 179, ISBN 1-56347-255-4, 1998, incorporated herein by this reference, provides additional details concerning “hit-to-kill” vehicles and blast fragmentation type warheads. Chapter 5 of that textbook, proposes a kinetic energy rod warhead. 
   In general, a kinetic energy rod warhead, in accordance with this invention, can be added to kill vehicle  14 ,  FIG. 3  to deploy lengthy cylindrical projectiles  40  directed at re-entry vehicle  10  or another target. In addition, the prior art blast fragmentation type warhead shown in  FIG. 2  can be replaced with or supplemented with a kinetic energy rod warhead  50 ,  FIG. 4  to deploy projectiles  40  at target  36 . 
   Two key advantages of kinetic energy rod warheads as theorized is that 1) they do not rely on precise navigation as is the case with “hit-to-kill” vehicles and 2) they provide better penetration then blast fragmentation type warheads. 
   To date, however, kinetic energy rod warheads have not been widely accepted nor have they yet been deployed or fully designed. The primary components associated with a theoretical kinetic energy rod warhead  60 ,  FIG. 5  is hull  62 , projectile core or bay  64  in hull  62  including a number of individual lengthy cylindrical rod projectiles  66 , sympethic shield  67 , and explosive charge  68  in hull  62  about bay or core  64 . When explosive charge  66  is detonated, projectiles  66  are deployed as shown by vectors  70 ,  72 ,  74 , and  76 . 
   Note, however, that in  FIG. 5  the projectile shown at  78  is not specifically aimed or directed at re-entry vehicle  80 . Note also that the cylindrical shaped projectiles may tend to break upon deployment as shown at  84 . The projectiles may also tend to tumble in their deployment as shown at  82 . Still other projectiles approach target  80  at such a high oblique angle that they do not penetrate target  80  effectively as shown at  90 . 
   In this invention, the kinetic energy rod warhead includes, inter alia, means for aligning the individual projectiles when the explosive charge is detonated and deploys the projectiles to prevent them from tumbling and to insure the projectiles approach the target at a better penetration angle. 
   In one example, the means for aligning the individual projectiles include a plurality of detonators  100 ,  FIG. 6  (typically chip slapper type detonators) spaced along the length of explosive charge  102  in hull  104  of kinetic energy rod warhead  106 . As shown in  FIG. 6 , projectile core  108  includes many individual lengthy cylindrical projectiles  110  and, in this example, explosive charge  102  surrounds projectile core  108 . By including detonators  100  spaced along the length of explosive charge  102 , sweeping shock waves are prevented at the interface between projectile core  108  and explosive charge  102  which would otherwise cause the individual projectiles  110  to tumble. 
   As shown in  FIG. 7 , if only one detonator  116  is used to detonate explosive  118 , a sweeping shockwave is created which causes projectile  120  to tumble. When this happens, projectile  120  can fracture, break or fail to penetrate a target which lowers the lethality of the kinetic energy rod warhead. 
   By using a plurality of detonators  100  spaced along the length of explosive charge  108 , a sweeping shock wave is prevented and the individual projectiles  100  do not tumble as shown at  122 . 
   In another example, the means for aligning the individual projectiles includes low density material (e.g., foam) body  140 ,  FIG. 9  disposed in core  144  of kinetic energy rod warhead  146  which, again, includes hull  148  and explosive charge  150 . Body  140  includes orifices  152  therein which receive projectiles  156  as shown. The foam matrix acts as a rigid support to hold all the rods together after initial deployment. The explosive accelerates the foam and rods toward the RV or other target. The foam body holds the rods stable for a short period of time keeping the rods aligned. The rods stay aligned because the foam reduces the explosive gases venting through the packaged rods. 
   In one embodiment, foam body  140 ,  FIG. 9  maybe combined with the multiple detonator design of  FIGS. 6 and 8  for improved projectile alignment. 
   In still another example, the means for aligning the individual projectiles to prevent tumbling thereof includes flux compression generators  160  and  162 ,  FIG. 10 , one on each end of projectile core  164  each of which generate a magnetic alignment field to align the projectiles. Each flux compression generator includes magnetic core element  166  as shown for flux compression generator  160 , a number of coils  168  about core element  166 , and explosive charge  170  which implodes magnetic core element when explosive charge  170  is detonated. The specific design of flux compression generators is known to those skilled in the art and therefore no further details need be provided here. 
   As shown in  FIG. 11 , kinetic energy rod warhead  180  includes flux compression generators  160  and  162  which generate the alignment fields shown at  182  and  184  and also multiple detonators  186  along the length of explosive charge  190  which generate a flat shock wave front as shown at  192  to align the projectiles at  194 . As stated above, foam body  140  may also be included in this embodiment to assist with projectile alignment. 
   In  FIG. 12 , kinetic energy rod warhead  200  includes an explosive charge divided into a number of sections  202 ,  204 ,  206 , and  208 . Shields such as shield  225  separates explosive charge sections  204  and  206 . Shield  225  maybe made of a composite material such as a steel core sandwiched between inner and outer lexan layers to prevent the detonation of one explosive charge section from detonating the other explosive charge sections. Detonation cord resides between hull sections  210 ,  212 , and  214  each having a jettison explosive pack  220 ,  224 , and  226 . High density tungsten rods  216  reside in the core or bay of warhead  200  as shown. To aim all of the rods  216  in a specific direction and therefore avoid the situation shown at  78  in  FIG. 5 , the detonation cord on each side of hull sections  210 ,  212 , and  214  is initiated as are jettison explosive packs  220 ,  222 , and  224  as shown in  FIGS. 13-14  to eject hull sections  210 ,  212 , and  214  away from the intended travel direction of projectiles  216 . Explosive charge section  202 ,  FIG. 14  is then detonated as shown in  FIG. 15  using a number of detonators as discussed with reference to  FIGS. 6 and 8  to deploy projectiles  216  in the direction of the target as shown in FIG.  15 . Thus, by selectively detonating one or more explosive charge sections, the projectiles are specifically aimed at the target in addition to being aligned using the aligning structures shown and discussed with reference to  FIGS. 6 and 8  and/or FIG.  9  and/or FIG.  10 . 
   In addition, the structure shown in  FIGS. 12-15  assists in controlling the spread pattern of the projectiles. In one example, the kinetic energy rod warhead of this invention employs all of the alignment techniques shown in FIGS.  6  and  8 - 10  in addition to the aiming techniques shown in  FIGS. 12-15 . 
   Typically, the hull portion referred to in  FIGS. 6-9  and  12 - 15  is either the skin of a missile (see  FIG. 4 ) or a portion added to a “hit-to-kill” vehicle (see FIG.  3 ). 
   Thus far, the explosive charge is shown disposed about the outside of the projectile or rod core. In another example, however, explosive charge  230 ,  FIG. 16  is disposed inside rod core  232  within hull  234 . Further included may be low density material (e.g., foam) buffer material  236  between core  232  and explosive charge  230  to prevent breakage of the projectile rods when explosive charge  230  is detonated. 
   Thus far, the rods and projectiles disclosed herein have been shown as lengthy cylindrical members made of tungsten, for example, and having opposing flat ends. In another example, however, the rods have a non-cylindrical cross section and non-flat noses. As shown in  FIGS. 17-24 , these different rod shapes provide higher strength, less weight, and increased packaging efficiency. They also decrease the chance of a ricochet off a target to increase target penetration especially when used in conjunction with the alignment and aiming methods discussed above. 
   Typically, the preferred projectiles do not have a cylindrical cross section and instead may have a star-shaped cross section, a cruciform cross section, or the like. Also, the projectiles may have a pointed nose or at least a non-flat nose such as a wedge-shaped nose. Projectile  240 ,  FIG. 17  has a pointed nose while projectile  242 ,  FIG. 18  has a star-shaped nose. Other projectile shapes are shown at  244 ,  FIG. 19  (a star-shaped pointed nose); projectile  246 ,  FIG. 20 ; projectile  248 ,  FIG. 21 ; and projectile  250 , FIG.  22 . Projectiles  252 ,  FIG. 23  have a star-shaped cross section, pointed noses, and flat distal ends. The increased packaging efficiency of these specially shaped projectiles is shown in  FIG. 24  where sixteen star-shaped projectiles can be packaged in the same space previously occupied by nine penetrators or projectiles with a cylindrical shape. 
   Thus far, it is assumed there is only one set of projectiles. In another example, however, the projectile core is divided into a plurality of bays  300  and  302 , FIG.  25 . 
   Again, this embodiment may be combined with the embodiments shown in FIGS.  6  and  8 - 24 . In  FIGS. 26 and 27 , there are eight projectile bays  310 - 324  and cone shaped explosive core  328  which deploys the rods of all the bays at different velocities to provide a uniform spray pattern. Also shown in  FIG. 26  is wedged shaped explosive charge sections  330  with narrower proximal surface  334  abutting projectile core  332  and broader distal surface  336  abutting the hull of the kinetic energy rod warhead. Distal surface  336  is tapered as shown at  338  and  340  to reduce the weight of the kinetic energy rod warhead. 
   In one test example, the projectile core included three bays  400 ,  402  and  404 , FIG.  28  of hexagon shaped tungsten projectiles  406 . The other projectile shapes shown in  FIGS. 17-24  may also be used. Each bay was held together by fiber glass wrap  408  as shown for bay  400 . The bays  400 ,  402  and  404  rest on steel end plate  410 . Buffer  407  is inserted around the rod core. This buffer reduces the explosive edge effects acting against the outer rods. By mitigating the energy acting on the edge rods it will reduce the spray angle from the explosive shock waves. 
   Next, explosive charge sections  412 ,  414 ,  416  and  418 ,  FIG. 29  were disposed on end plate  410  about the projectile core. Thus, the primary firing direction of the projectiles in this test example was along vector  420 . Clay sections  422 ,  424 ,  426  and  428  simulated the additional explosive sections that would be used in a deployed warhead. Between each explosive charge section is sympathetic shield  430  typically comprising steel layer  432  sandwiched between layers of Lexan  434  and  436 . Each explosive charge section is wedge shaped as shown with proximal surface  440  of explosive charge section  412  abutting the projectile core and distal surface  442  which is tapered as shown at  444  and  446  to reduce weight. 
     65  Top end plate  431 ,  FIG. 30  completes the assembly. End plates  410  and  431  could also be made of aluminum. The total weight of the projectile rods  406  was 65 lbs, the weight of the C4 explosive charge sections  412 ,  414 ,  416 , and  418  was 10 lbs. Each rod weighed 35 grams and had a length to diameter ratio of 4. 271 rods were packaged in each bay with 823 rods total. The total weight of the assembly was 30.118 lbs. 
     FIG. 31  shows the addition of detonators as shown at  450  just before test firing. There was one detonator per explosive charge section and all the detonators were fired simultaneously.  FIGS. 32-33  shows the results after test firing. The individual projectiles struck test surface  452  as shown in FIG.  32  and the condition of certain recovered projectiles is shown in FIG.  33 . 
   To reduce the deployment angles of the projectiles when the detonators detonate the explosive charge sections thereby providing a tighter spray pattern useful for higher lethality in certain cases, several additional structures were added in the modified warhead of FIG.  34 . 
   One means for reducing the deployment angles of projectiles  406  is the addition of buffer  500  between the explosive charge sections and the core. Buffer  500  is preferably a thin layer of poly foam ½ inch thick which also preferably extends beyond the core to plates  431  and  410 . Buffer  500  reduces the edge effects of the explosive shock waves during deployment so that no individual rod experiences any edge effects. 
   Another means for reducing the deployment angles of the rods is the addition of poly foam buffer disks  510  also shown in FIG.  35 . The disks are typically ⅛ inch thick and are placed between each end plate and the core and between each core bay as shown to reduce slap or shock interactions in the rod core. 
   Momentum traps  520  and  522  are preferably a thin layer of glass applied to the outer surface of each end plate  410  and  431 . Also, thin aluminum absorbing layers  530  and  532  between each end plate and the core help to absorb edge effects and thus constitute a further means for tightening the spray pattern of the rods. 
   In some examples, selected rods  406   a ,  406   b ,  406   c , and  406   d  extend continuously through all the bays to help focus the remaining rods and to reduce the angle of deployment of all the rods. Another idea is to add an encapsulant  540 , which fills the voids between the rods  406 , FIG.  36 . The encapsulant may be glass and/or grease coating each rod. Preferably, there are a plurality of spaced detonators  450   a ,  450   b , and  450   c ,  FIG. 34  for each explosive charge section each detonator typically aligned with a bay  400 ,  402 , and  404 , respectively, to provide a flatter explosive front and to further reduce the deployment angles of rods  406 . Another initiation technique could be used to reduce edge effects by generating a softer push against the rods. This concept would utilize backward initiation where the multiple detonators  450   a′ ,  450   b′ , and  450   c′ are moved from their traditional location on the outer explosive to the inner base proximate buffer  500 . The explosive initiators are inserted at the explosive/foam interface which generates a flat shock wave traveling away from the rod core. This initiation logic generates a softer push against the rod core reducing all lateral edge effects. 
   Another idea is to use rod  406   e ,  FIG. 37  at select locations or even for all the rods. Rod  406   e  extends through all the bays but includes frangible portions of reduced diameter  560  and  562  at the intersection of the bays, which break upon deployment dividing rod  406   e  into three separate portions  564 ,  566 , and  568 . 
   The result with all, a select few, or even just one of these exemplary structural means for reducing the deployment angles of the rods or projectiles when the detonator(s) detonate the explosive charge sections is a tighter, more focused rod spray pattern. Also, the means for aligning the projectiles discussed above with reference to  FIGS. 6-11  and/or the means for aiming the projectiles discussed above with reference to  FIGS. 12-15  maybe incorporated with the warhead configuration shown in  FIGS. 34-35  in accordance with this invention. 
   Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments. 
   Other embodiments will occur to those skilled in the art and are within the following claims: