Abstract:
A composite sabot including an anti-splitting ring connected to the composite sabot body, to prevent the sabot from splitting during discard. The composite sabot includes sabot petals with fibers oriented in the radial direction and a front scoop for gathering air particles. The anti-splitting ring is mounted to the front scoop portion of the composite sabot where splitting initiates. The anti-splitting ring may be a variety of shapes and materials and attaches easily and inexpensively to any sabot.

Description:
U.S. GOVERNMENT RIGHTS 
     The United States Government has certain rights to this invention under government contract number DAAE30-97-C-1006. 
    
    
     FIELD OF THE INVENTION 
     The present invention is generally related to sabots, and more particularly to a composite sabot with an anti-splitting ring integral therewith. 
     BACKGROUND OF THE INVENTION 
     In military ordnance arts, carriers for projectiles, known as sabots, have been used to facilitate the use of a variety of munitions while engaging in military operations. 
     In general, a sabot is a lightweight carrier for a projectile that permits the firing of a variety of projectiles of a smaller caliber within a larger caliber weapon. The word sabot is derived form the French word cabot, which means, “shoe.” Because a sabot fits around the projectile in a manner similar to the way a cabot, or “shoe,” slips onto a persons foot, the name has been applied to all such projectile carriers. 
     A sabot provides structured support to a flight projectile within a gun tube under extremely high loads. Without adequate support from a sabot, a projectile may break up into many pieces when fired. 
     A sabot fills the bore of the gun tube while encasing the projectile to permit uniform and smooth firing of the weapon. The projectile is centrally located within the sabot that is generally radially symmetrical. After firing, the sabot and projectile clear the bore of the gun tube and the sabot is normally discarded some distance from the gun tube while the projectile continues toward the target. 
     One method for discarding a sabot is to form a scoop onto the sabot. After the sabot and projectile clear the weapon bore, the scoop gathers, or “scoops,” air particles as it is moving forward. The air pressure on the front scoop lifts the sabot from the projectile and thus the sabot is removed from the projectile in flight, allowing the projectile to continue towards its target. 
     Additionally, sabots are generally made in three symmetrical segments to facilitate smooth discard upon exit from the gun. Typically, each segment, or petal, spans 120 degrees of the front circumference of the intact sabot. Each petal&#39;s scoop portion is still expansive enough, at 120-degrees, to serve its purpose of driving the petal away from the projectile. The three segment design allows sabot petals to discard from the projectile quickly, as opposed to, for example, a design where an intact sabot gradually slips off of the projectile. The overall advantage of a three petal sabot design is that the sabot is released more quickly, thereby reducing parasitic weight and increasing accuracy. 
     It is desirable to make sabots lightweight to increase the muzzle velocity of projectile at exit. At the same time, the sabot must maintain its rigidity during operation. For example, inside the bore of the weapon the sabot must stay rigid to allow smooth firing and accurate targeting. Further, once outside the bore of the weapon, the sabot must maintain rigidity in order to scoop air particles efficiently, discard its three petals, and allow acceptable projectile dispersion on the target. 
     The weight of sabots has been reduced considerably through the use of continuous fiber composite material. Generally, such composite sabots are mixtures of fibers and epoxy combined in a chemical molding process. The weight reductions are made possible by aligning the fibers in the longitudinal/radial plane of the sabot which matches the load directions generated during the projectile travel down the weapon bore. 
     Unfortunately, during sabot discard, significant circumferential, or hoop, tensile loads are created. Since no fibers are oriented in the circumferential, or hoop, direction in known lightweight sabot designs, the sabot splits along the longitudinal/radial plane typically near the middle of the sabot scoop. Compounding the problem, a faulty molding process may leave air voids in the structure of the sabot, which increases the probability that a sabot petal of conventional design will split into more than two pieces. 
     Consequently, composite sabot petals of conventional design usually split in the middle from the high hoop stresses generated during discard. Thus, a 120-degree petal may split into two 60-degree segments due to the lack of strength in the circumferential direction of the sabot. This could result in asymmetric discard, where the petals are released at different times, and poor projectile dispersion on the target. It also has been found that a 60-degree segment of split sabot petal is more likely to fail in the scoop or break in the saddle compared to 120-degree intact sabot petal. Further, such splits occur with considerable variation in the location and time of splitting. Thus, compensation for the sabot failure using targeting adjustments is very difficult. 
     Previous attempts to stop the splitting of composite sabots involved filament wrapping. In this process, the entire assembled projectiles are wrapped with filaments, and then the filament wrap is slit along the seams between the sabot petals. However, this process is unwieldy and expensive from a manufacturing standpoint. Further, filament wrapping is known to be ineffective for preventing all sabot splitting problems. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the deficiencies of the prior art by, for the first time, providing a lightweight, reliable, and inexpensive method of eliminating splitting of a composite sabots during discard using an anti-splitting ring within a composite sabot. The present invention provides a composite sabot that discards more uniformly thereby allowing increased accuracy and dispersion of projectiles fired with composite sabots. Further, the present invention provides a composite sabot design that decreases the drag on and increases velocity of a projectile fired with composite sabots. 
     The invention provides, for the first time, a composite sabot having an anti-splitting ring mounted to the sabot to prevent the composite sabot from splitting during discard. 
     In one example embodiment of the invention, a composite sabot includes sabot petals with fibers oriented in the radial direction and a front scoop for gathering air particles. An anti-splitting ring is mounted to the front scoop portion of the composite sabot where splitting initiates. The anti-splitting ring may be a variety of shapes and materials and attaches easily and inexpensively to any sabot. 
     Other objects, features and advantages of the present invention will become apparent to those skilled in the art through the description of the preferred embodiment, claims and drawings wherein like numerals refer to like elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a three dimensional perspective view of one example of the apparatus of the invention employed on a composite sabot. 
     FIG. 2A is a front view of one example of the apparatus of the invention employed on a composite sabot. 
     FIG. 2B is a partial view of one example of the apparatus of the invention as depicted in FIG.  2 A. 
     FIG. 3A is a cross-sectional side view of one example of the apparatus of the invention employed on a composite sabot. 
     FIG. 3B is a partial view of one example of the apparatus of the invention as depicted in FIG.  3 A. 
     FIG. 4A is a partial cross-sectional side view of an alternative example of the apparatus of the invention employed on a composite sabot. 
     FIG. 4B is a partial cross-sectional side view of an alternative example of the apparatus of the invention employed on a composite sabot. 
     FIG. 4C is a partial cross-sectional side view of an alternative example of the apparatus of the invention employed on a composite sabot. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Illustrated in FIG. 1 is a three dimensional perspective view of a composite sabot  10  in accordance with the present invention. The composite sabot  10  has a sabot body  20 , an anti-splitting ring  50 , and a penetrator  60 . 
     The sabot body  20  has a front scoop  30  for trapping air particles. The front scoop has a front edge  40  for mounting the anti-splitting ring  50 . In this example of the present invention, the sabot body  20  is nominally radially divided along three petal divisions  24  into three 120-degree sabot petals  22 . Each sabot petal  22  has a front scoop segment  32 . Each front scoop segment  32  has a front edge segment  42 . Accordingly, the anti-splitting ring  50  is also nominally divided along three ring divisions  54  into three 120-degree anti-splitting ring segments  52  (shown in FIG.  2 B). In one useful embodiment, the petal divisions  24  and the ring divisions  54  are advantageously aligned so that one ring segment  52  substantially covers a mating front edge segment  42 . Fully assembled, the sabot petals  22  and the anti-splitting ring segments  52  encompass the penetrator  60 . 
     When fired, and after the composite sabot  10  exits from a gun tube, the sabot body  20  releases the penetrator  60 . Release occurs as the front scoop  30  traps or “scoops” air particles. The air particles create lift forces  70  that separate the sabot body  20 , along the petal divisions  24 , into its corresponding sabot petals  22 . Accordingly, as the sabot body  20  separates, the anti-splitting ring  50  also separates along the ring divisions  54 . As the sabot petals  22  are separating, the front scoop segments  32  provide enough surface area to allow total separation from and release of the penetrator  60 . This release process is called discard. 
     Illustrated in FIG. 2A is a front view of the front scoop  30  of a composite sabot of the present invention taken generally along the line  2 A— 2 A of FIG.  1 . This view shows the front scoop  30  with the front edge  40 . The anti-splitting ring  50  is mounted on the front edge  40 , and thus, hides the front edge  40  from view. The anti-splitting ring  50  may be integrally connected to the front edge  40  or mounted using a wide variety of known structural adhesives. This view more clearly shows that the ring divisions  54  are aligned with the petal divisions  24  and that the fully assembled sabot petals encompass the penetrator  60 . 
     Further, FIG. 2A shows the high hoop stresses  220  that are generated on the front scoop segments  32  during discard. The anti-splitting ring  50  prevents the hoop stresses  220  from splitting the front edge segments  42  (shown in FIG. 1 and 2B) of the sabot petals  22  throughout the entire discard process. 
     Illustrated in FIG. 2B is a detailed partial view of the front scoop segment  32  of FIG.  2 A. Front scoop segment  32  has wedges  210  aligned in the radial direction. Each wedge  210  is comprised of wedge fibers  212  aligned in the same direction as the wedges  210 . The radial alignment of the wedges  210  matches loads created during the firing of the composite sabot  10 . 
     However, during discard, the high hoop stresses  220  generate loads in the circumferential direction; thus, the wedges  210  are not oriented in the proper direction to withstand the hoop stresses  220 . Consequently, the wedges  210  begin to split. In other mechanisms built without the benefit of the anti-splitting ring of the invention, splitting would initiate in the middle of a front edge segment  42  at split point  230  and travel down the length of the sabot petal  22  as the wedges  210  progressively fail. 
     Further, in such other devices, when splitting occurs, it also has been found that the front scoop segment  32  will fail to provide sufficient trapping of air particles after the sabot petals  22  have begun to separate. Consequently, discard could be asymmetric or the sabot petals  22  could break. 
     As mentioned hereinabove, the anti-splitting ring  50  of the invention advantageously prevents the hoop stresses  220  from splitting the front edge segments  42 . The anti-splitting ring  50  prevents splitting because it is oriented in the same direction as the hoop stresses  220  and provides the wedge fibers  212  with sufficient circumferential strength to withstand splitting. The anti-splitting ring segments  52  also prevent the front scoop segments  32  from splitting, to allow for proper release of the penetrator  60  throughout the discard process. 
     Illustrated in FIG. 3A is a cross-sectional view of the composite sabot  10  of the present invention taken generally along the line  3 A— 3 A of FIG.  2 A. This view shows a portion of sabot body  20 , anti-splitting ring  50 , and a portion of penetrator  60 . The anti-splitting ring  50  is mounted to the front edge  40  of front scoop  30 . 
     Illustrated in FIG. 3B is a detailed partial view of the front scoop  30  of FIG.  3 . This view shows front scoop  30  with front edge  40 . The anti-splitting ring  50  is mounted to front edge  40 . In this example of the present invention, the anti-splitting ring  50  has a U-shaped cross-section  310 . 
     The anti-splitting ring  50  of FIG. 3A has a first bottom wall  320 , a first front wall  322 , and a top wall  324  that combine to form the U-shape cross-section  310  of this example of the anti-splitting ring  50 . The U-shape cross-section  310  allows the anti-splitting ring  50  to easily mate with the front edge  40  providing circumferential strength to front scoop  30  and the wedge fibers  212  (as shown in FIG.  2 B). The anti-splitting ring  50  with the U-shape cross-section  310  also reinforces and encloses the split point  230 . 
     Illustrated in FIG. 4A is an alternate embodiment of the present invention with a detailed partial view of the front scoop  30  with a second anti-splitting ring  408 . This view shows front scoop  30  with front edge  40 . A second anti-splitting ring  408  is mounted to front edge  40 . In this example of the present invention, the second anti-splitting ring  408  has an L-shaped cross-section  410 . 
     The second anti-splitting ring  408  of FIG. 4A has a second bottom wall  412  and a second front wall  414  that combine to form the L-shape cross-section  410  of the second anti-splitting ring  408 . The L-shape cross-section  410  allows the second anti-splitting ring  408  to easily couple with the front edge  40  providing circumferential strength to front scoop  30  and the wedge fibers  212  (as shown in FIG.  2 B). The second anti-splitting ring  408  with the L-shape cross-section  410  also reinforces and encloses the split point  230 . 
     Illustrated in FIG. 4B is an alternate embodiment of the present invention with a detailed partial view of the front scoop  30  with a third anti-splitting ring  418 . This view shows front scoop  30  with front edge  40 . The third anti-splitting ring  418  is mounted to front edge  40 . In this example of the present invention, the third anti-splitting ring  418  has a curved cross-section  420 . 
     The third anti-splitting ring  418  of FIG. 4B has a first single wall  422  that forms the curved cross-section  420  of this example of the third anti-splitting ring  418 . The curved cross-section  420  allows the third anti-splitting ring  418  to connect with the front edge  40  providing circumferential strength to front scoop  30  and the wedge fibers  212  (as shown in FIG.  2 B). The third anti-splitting ring  418  with the curved cross-section  420  also reinforces the split point  230 . 
     Illustrated in FIG. 4C is an alternate embodiment of the present invention with a detailed partial view of the front scoop  30  with a fourth anti-splitting ring  428 . This view shows front scoop  30  with front edge  40 . The fourth anti-splitting ring  428  is mounted to front edge  40 . In this example of the present invention, the fourth anti-splitting ring  428  has a rectangular cross-section  430 . 
     The fourth anti-splitting ring  428  of FIG. 4C has a second single wall  432  that forms the rectangular cross-section  430  of this example of the fourth anti-splitting ring  428 . The rectangular cross-section  430  allows the fourth anti-splitting ring  428  to connect with the front edge  40  providing circumferential strength to front scoop  30  and the wedge fibers  212  (as shown in FIG.  2 B). The fourth anti-splitting ring  428  with the rectangular cross-section  430  also reinforces the split point  230 . 
     The invention has been described herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles of the present invention, and to construct and use such exemplary and specialized components as are required. However, it is to be understood that the invention may be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment details and operating procedures, may be accomplished without departing from the true spirit and scope of the present invention. 
     More specifically, materials for anti-splitting ring  50  may be chosen from a wide array of materials to serve the intended purpose. The material may be selected from a wide array of metallic materials and alloys, as well as, composite fiber, thermoset or thermoplastic resins and epoxies to serve the intended function and accommodate manufacturing processing to achieve the integral structure as indicated herein. Other resins known to one skilled in the art may be employed as appropriate, 
     For example, the anti-splitting ring of the invention may advantageously be comprised of material selected from the group consisting of metal, a continuous fiber/epoxy system, a chopped fiber/epoxy system, a thermoset fiber/epoxy system, a thermoplastic fiber/epoxy system, a continuous thermoset fiber/epoxy system, a chopped thermoset fiber/epoxy system, a continuous thermoplastic fiber/epoxy system, a chopped thermoplastic fiber/epoxy system, a thermoset fiber/resin system, a thermoplastic fiber/resin system, a continuous thermoset fiber/resin system, a chopped thermoset fiber/resin system, a continuous thermoplastic fiber/resin system, and a chopped thermoplastic fiber/resin system. 
     As a further example, fibers employed for making the anti-splitting ring may advantageously include glass fibers, graphite fibers, carbon fibers, boron fibers or any other fibrous materials suitable for making lightweight anti-splitting rings. Suitable metals include aluminum, and any other suitable metal or metal alloys. The anti-splitting ring may be shaped and manufactured using any well known machining or other fabrication techniques from the metal arts or the composite fiber arts as the case may be. 
     Lastly, the anti-splitting ring  50  may have many possible configurations in addition to those configurations shown in FIGS.  3 B and FIGS. 4A-4C. These and other modifications are all intended to be within the true spirit and scope of the present invention.