Patent Publication Number: US-8109213-B1

Title: Multipurpose target breaching warhead

Description:
U.S. GOVERNMENT INTEREST 
     The inventions described herein may be made, used, or licensed by or for the U.S. Government for U.S. Government purposes. 
    
    
     BACKGROUND AND SUMMARY OF INVENTION 
     This invention relates to the field of ammunition for breaching a hardened target. There is a long felt need for more effective warheads to breach such targets, and especially a need to have a single projectile, multipurpose in nature, for clearing a variety of different types of targets. Current targets each require a specialized projectile. For example, presently an M830A1 round may be used for breaching steel reinforced concrete walls; an M1028 round may be used against light armor targets; an M830 round may be used for defeating bunkers; and an M908 round may be used for antipersonnel applications. Clearly, if a single projectile could effectively be used for any of these type of targets, huge savings in time, money, and logistics could be realized. 
     In striking a target barrier wall of steel double reinforced concrete perhaps 8 inches thick, many current projectiles are not able to penetrate very deeply. Most current projectiles launched against such barriers flatten out before being able to penetrate, then explode and the projectile warhead breaks into fragments. Although some warhead fragments will penetrate forward into the barrier as intended, yet many fragments will not and only be deflected off the barrier. Although the flattening may create a larger area of surface impact, the desired effect of clearing the target obstacle from its path isn&#39;t necessarily optimized. In most cases, the warhead actually fragments in the opposite direction of the course of the projectile, away from the target, and the barrier does not receive the full effect of the explosive energy. What is needed is a projectile that is able to penetrate comparatively deep into a concrete barrier before exploding, with resulting fragments thereof all penetrating into the target. A projectile is described in this invention which is capable of puncturing a double reinforced concrete wall, projectile essentially fully intact, and only then to have its warhead explode into fragments. This allows fragmentation in a more effective nearly ideal direction. 
     OBJECTS OF THE INVENTION 
     It is an object of the present invention to provide an extremely more effective projectile and warhead to breach double steel reinforced concrete barriers, and; 
     It is a further object of the present invention to also provide an effective projectile and warhead to breach other hardened targets, such as bunkers, light armor and antipersonnel applications, and; 
     It is a still further object of the present invention to provide a multipurpose projectile and warhead to breach all of double steel reinforced concrete barriers, bunkers, light armor and antipersonnel applications, all with a single projectile, and; 
     It is a yet another object of the present invention to provide logistical and other savings by providing a single multipurpose projectile for use against a variety of hardened targets, including but not limited to double steel reinforced concrete barriers, bunkers, light armor and antipersonnel applications. 
     These and other objects, features and advantages of the invention will become more apparent in view of the within detailed descriptions of the invention and in light of the following drawings. It should be understood that the sizes and shapes of the different components in the figures may not be in exact proportion and are shown here for visual clarity and for purpose of explanation. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a cross section of a projectile warhead generally according to this invention. 
         FIG. 2  shows a cross section of an overall cartridge employing the projectile warhead design features according to this invention. 
         FIG. 3A  and  FIG. 3B  illustrate less successful versus more successful degrees of penetration of a projectile achieved by this invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a cross section of a projectile warhead generally according to this invention.  FIG. 2  shows a cross section of an overall cartridge employing the projectile warhead design features according to this invention.  FIG. 3B  and  FIG. 3A  indicate successful versus less successful degrees of penetration of a projectile compared to the benefits of this invention. In a target wall of steel double reinforced concrete  302 , perhaps 8 inches thick, many projectiles  301  are not able to penetrate very deeply. The projectile flattens out before being exploded, then its warhead fragments. Although some warhead fragments  304  will penetrate forward into the barrier  302  as intended, yet many fragments  306 , e.g., will not accomplish this intent and only be deflected off the barrier  302  as illustrated. Although the flattening creates a larger area of surface impact, the desired effect of clearing the target obstacle from its path isn&#39;t necessarily optimized. This is especially true of reinforced targets such as double reinforced concrete walls. In most cases, the warhead fragments in the opposite direction of the course of the projectile. Much fragmentation thus occurs away from the target and it does not receive the full effect of the explosive energy. This invention follows instead the scenario in  FIG. 3B . Here, projectile  300  is able to penetrate comparatively deeply into concrete barrier  302  before exploding, with resulting fragments  308  thereof all penetrating into the target  302  (as well as the other fragments such as  305 ). This projectile is able to puncture a double reinforced concrete wall, projectile fully intact. This allows the explosives to have a better chance of creating the ideal effect. Another advantage is directional in that fragmentation can occur in a more effective direction. And a further advantage is timing. With electronic timed fuzing, the most effective breaching capabilities can be realized. While the invention is described here in terms of breaching reinforced concrete walls, this same projectile is intended to also be able to breach light armor targets, bunkers, used in munitions for urban terrain warfare, and also used for antipersonnel purposes. This is meant to be one projectile (multipurpose) that can accomplish many applications including these. Presently required is an M830A1 for breaching the concrete walls, an M1028 for light armor, an M830 for defeating bunkers, and an M908 for antipersonnel applications. In  FIG. 1 , a projectile  100  is shown. The casing  101  (with an interior surface  119 ) is made of 300M steel. This material is much like  4340  steel however, the percentage of silicon has been increased to allow for higher hardenability and an increase in elongation. This material to our knowledge has not been used in any other warhead design. The thickness  113  of the warhead nose  111 , combined with the properties of the 300M steel, was designed to allow for a near three times volume expansion (compared to a more conventional projectile). This then increases the fragmentation velocity upon detonation which maximizes the desired effect of the projectile. The outer profile  115  of the nose  111  and the inner profile  117  of the nose  111  are computer generated splines (curved surfaces to connect two or more points) that allow for the maximum explosive energy discharge and maximum fragment velocity. Nose areas  121  are notched. The projectile has midway bourrelets  103  around the outside surface, and also bourrelets  105  at the aft portion of the projectile. They are a ring of material which is softer than the projectile material, to act as seal against propellant gases escaping between the space between projectile and barrel. The bourrelet locations of  103  versus  105  are specifically selected so that the center of gravity  107  of the entire projectile (including all parts from windscreen to boom) is directly in between the two bourrelets; this done to create more bore stability. This means that there is less movement in the barrel of the gun which, in return, allows a more consistent launch. There is a member  122  near the aft area of the round for purposes of support for the casing  101 .  FIG. 2  shows a full up cartridge  200  utilizing attached at the fore end thereof, a projectile and warhead analogous throughout to the projectile and warhead  100  shown in  FIG. 1  hereof, according to this invention. The cartridge has a base data link  201 , the back cartridge area is filled with JA-2 propellant; the cartridge includes a front projectile with PAX-3 high explosive  217  (base loaded), a warhead having a pre-fragmented tungsten nose  211 , a point detonate switch  213 , a base detonating fuze  207  (multi mode programmable), warhead closure disc  209 , and a projectile body having folding fins  205 . 
     While the invention has been described with reference to certain embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof.