Projectile with low velocity radial deployment of elements with predetermined pattern

Abstract: A plurality of objects is deployed in generally radial directions at low velocities in order to achieve a predetermined pattern of the deployed objects. The device has a metal inner wall member (20, 120) having a plurality of annular cylindrical segments of differing outside diameters, an explosive body (22, 122) of low velocity explosive, and a plurality of arrays (40, 140) positioned coaxially with and exteriorly of the explosive body (22, 122) and spaced along the length of the explosive body (22, 122). Each array (40, 140) comprises a plurality of objects (28). The explosive body (22, 122) can be in the form of a plurality of annular sections which provide the objects (28) in each array with an amount of energy different from that provided to each of the objects in the adjacent array. An annular flange (32) can separate the forward end of the explosive body (22, 122) from a booster ring (66), or the booster ring (166) can be positioned within a central cavity of the inner wall member (120). A plurality of holes (168) in the inner wall member (120) can expose the explosive body (122) to the detonation of the booster ring (166). The holes (168) can be aligned with the objects (28) in the radially adjacent array and/or aligned with points between adjacent objects. Outwardly extending flanges (32, 34 or 132, 134) can serve as reflection surfaces for explosive pressure waves. One or more safe arm fuzes (90, 92, 190) can be encased in foam (94, 194) and positioned within an annular structure (76, 120). An annular explosive section can be in the form of discrete segments spaced apart about the circumference of the explosive body.

Description: FIELD OF THE INVENTION This invention relates to a device for deploying a plurality of precisely shaped objects at low velocities to provide a desired dispersed pattern of the objects. The invention can be employed in an interceptor missile for the purpose of increasing the area of potential impact with a target. Such a device is known from FR-A-2 287 671 which describes the preamble of claims 1 and 4. BACKGROUND OF THE INVENTION Two basic approaches to endoatmospheric non-nuclear destruction of an incoming missile or aircraft are 1) hit-to-kill by directly impacting the target with a large, heavy interceptor mass at high velocity, and 2) blast-fragmentation involving multiple impacts of small fragments at very high velocities and strike angles (from the interceptor's nose) resulting from the explosion of a high explosive warhead in the interceptor in the vicinity of the ballistic missile. The hit-to-kill or kinetic energy technology approach is based on the fact that when one object strikes another object at high speeds, a tremendous amount of destructive energy is released. The impact of an interceptor missile with an incoming tactical ballistic missile, aircraft, or cruise missile, can result in the total disintegration of both vehicles. Such impact can literally vaporize even metals. In contrast, blast-fragmentation warheads may only redirect or break up the target vehicle. However, even with a large hit-to-kill interceptor, the effective impact window is relatively small. Cordle et al, U.S. Patent 3,498,224, discloses a fragmentation warhead comprising a solid high explosive charge surrounded by a series of five axially spaced steps, with each of four of the steps containing a different number of circumferential layers of steel cubes to yield a fragment beam pattern made up of fragments having varying velocities. As illustrated in Figure 5 of Cordle et al, each of the deployment velocities is substantially greater than the missile velocity V M . The five steps could be considered to be five separate warheads joined in tandem, with each warhead section employing a different uniform charge-to-metal ratio. The fragmentation pattern presented to an area some uniform distance away (large in proportion to the size of the warhead) is said to be extremely dense and in a relatively narrow beam on the order of 10° wide. The fragments are identified as 4,76 mm (3/16 inch) steel cubes, with the weight of each of the fragments being 13 grains. Thomanek, U.S. Patent 3,474,731, describes a fragmentation warhead for use against personnel in an armored target. The warhead has a fragmentation casing arranged to separate into a multiplicity of elements upon detonation of the high explosive charge. The elements, which can be embedded in a synthetic resin, can be spherical, disk-shaped, or irregularly shaped. The fragmentation casing can be configured to direct the fragmentation elements in a number of specific directions. Kempton, U.S. Patent 4,026,213, discloses an aimable warhead having a thin metal outer skin and a stronger inner metal casing. The high explosive is contained in the annular space between the two shells, and is in contact with a plurality of circumferentially spaced initiators. A selected initiator can be fired to rupture an arcuate section of the outer skin while not causing a detonation of the main charge, and then another initiator can be fired to detonate the main charge, thereby fragmenting the thicker inner casing and driving the fragments through the ruptured arcuate section. Throner, Jr., U.S. Patent 3,263,612, describes a fragmentation weapon wherein the fragments in a first group of fragments are large in size and the fragments in a second group of fragments are smaller in size. The fragments can be positioned about a charge of high explosive and initially bonded together by a matrix of plastic resin and then covered with a sheath formed from fiberglass impregnated with plastic resin. Each of the larger fragments can have a mass of about 9,1 g (140 grains) while each of the smaller fragments can have a mass of about 1,9 g (30 grains). Although the shape of the fragments is stated to not be critical, cubes are preferred. Reach, Jr. et al. U.S. Patent 4,430,941, describes a projectile in which packs of flechettes by a frangible matrix of small smooth glass microspheres bound together and the flechettes from being damaged during acceleration of the projectile. Bourlette , U.S. Patent4,303,015, describes a pre-fragmented explosive shell wherein a plurality of balls is housed in an annulus about a high explosive charge. The balls can have a tungsten or tungsten carbide core with a zirconium coating. EP-A-0338 874 describes a projectile having an inner member and an annular body of explosive, wherein that inner member comprises a plurality of sections of different diameter and that annular body of explosive comprises a plurality of explosive sections being positioned coaxially with and exteriorly of the substantially cylindrical outer surface of a respective one of the sections of that inner member. US-A-4 768 440 discloses a warhead for a guided missile comprising a fragmantation casing, an outer explosive charge in shape of an annular body contained in the casing with an associated detonator and an inner explosive charge radially separated from the outer charge by an empty space and having also an associated detonator. Said detonators have the shape of wings respectively coaxial with the corresponding explosive charge and axially adjacent to the respective charge. While most of the foregoing patents disclose warheads producing fragment patterns utilizing discrete small pre-formed fragments, none discloses the use of a "slow" or low explosive propellant to radially deploy a plurality of precisely shaped high mass objects at low velocities to provide a desired dispersed pattern of the objects, whereby the effective hit-to kill window is enhanced. EP-A-0718590, which is a state of the art according to Art. 54 (3) EPC discloses a device for deploying a plurality of objects in generally radial directions at a low velocity in order to achieve a predetermined pattern of the deployed objects, said device comprising: an inner wall member; a annular body of low velocity explosive positioned exteriorly of and coaxially with the inner wall member; a plurality of annular arrays positioned coaxially with and exteriorly of the annular body of low velocity explosive, each annular array comprising a plurality of objects, the annular arrays being positioned at different locations along the central longitudinal axis of the annular body of low velocity explosive such that the energy provided each of the objects in a first annular array by the amount of the low velocity explosive in radial alignment with the first annular array is different from the energy provided each of the objects in a second annular array by the amount of the low velocity explosive in radial alignment with the second annular array. Each of the objects can have a shape which minimizes aerodynamically induced deviations in the path of the object during the deployment of the object, a mass of at least 50 g, and a density of at least 15 g/cm 3 . The objects can be positioned in a matrix of a synthetic polymeric material containing hollow glass microspheres. The low velocity explosive has a detonation velocity of less than 5000 meters per second and more preferably less than 4000 meters per second. The resulting radial deployment velocity of the objects is preferably less than about 182,4m (600 feet) per second and more preferably less than about 152m (500 feet) per second. Thus, in accordance with the concept described above, the hit-to-kill effect can be enhanced by a small, lightweight, agile interceptor that does not pre-empt a direct hit, and which incorporates a small number of fragments of high mass density which are deployable in a desired pattern with low deployment velocities and low strike angles, thereby substantially increasing the effective impact window. However, it is desirable that improvements be made in this device. SUMMARY OF THE INVENTION Such improvements, in accordance with the present invention are achieved by a device as defined in claim 1 or claim 4. In one embodiment the inner wall member is formed as a plurality of annular wall sections spaced along the central longitudinal axis, with each of the annular wall sections having a substantially cylindrical outer surface, and with adjacent annular wall sections having differing outer diameters. Similarly, the annular body of low velocity explosive comprises a plurality of annular explosive sections, with each of the annular explosive sections being positioned coaxially with and exteriorly of the substantially cylindrical outer surface of a respective one of the annular wall sections. Each of the annular arrays is positioned coaxially with and exteriorly of a respective one of the annular explosive sections. Each of the annular explosive sections can have a different radial thickness such that each of the annular explosive sections has an amount of low velocity explosive which is different from the amounts of low velocity explosive in the other annular explosive sections. Thus, the energy provided to the objects in a first one of the plurality of annular arrays by the annular explosive section radially adjacent thereto can be different from the energy provided to the objects in a second one of the plurality of annular arrays by the annular explosive section radially adjacent thereto. An outwardly extending annular flange can be provided at the front end of the annular body of explosive and an outwardly extending annular member can be provided at the rear end of the annular body of explosive to act as reflective surfaces for explosive pressure waves in the annular body of low velocity explosive. A booster ring is positioned radially inwardly of the forwardmost one of the plurality of annular wall member sections, and the forwardmost annular wall section is provided with a plurality of holes extending at least generally radially therethrough so that the booster ring initially fires the forwardmost annular explosive section. In one embodiment of the fourth aspect of the invention, the plurality of holes includes a first group of holes and a second group of holes at spaced locations about the circumference of the forwardmost annular wall section. Each of the first group of holes is positioned in radial alignment with a respective one of the objects of the forwardmost annular array, while each of the second group of holes is positioned in radial alignment with an intermediate point between a respective pair of the objects of the forwardmost annular array. Each pair of objects having one of the second group of holes therebetween can be positioned between two of the first group of holes. This arrangement provides for greater energy levels to be imparted to the objects in radial alignment with a hole than is imparted to the other objects in the forwardmost array. In one further embodiment, each of the holes in the forwardmost annular wall section is positioned so as to be in radial alignment with a respective one of the objects of the forwardmost first annular array. In another embodiment each of the holes in the forwardmost annular wall section is positioned so as not to be in radial alignment with any of the objects of the forwardmost first annular array. In particular, each hole can be equally spaced from adjacent objects. The safe arm fuze for the booster ring may be positioned radially inwardly of the annular wall member, thereby reducing the required length of the device. A second safe arm fuze can also be provided. If desired, the two safe arm fuzes can be encased in shock attenuating foam. The inner wall member can be formed of a metal, e.g., aluminum, in order to provide greater strength. In another embodiment at least one of the plurality of annular explosive sections can be in the form of a plurality of individual annular segments spaced apart from each other about the circumference of the annular explosive section. This configuration permits a savings in the amount of low explosive material when the objects in the radially adjacent array are spaced apart a significant distance. Brief Description Of The Drawings Fig.1 is a side view of a missile; Fig. 2 is an illustration of the pattern of objects which can be obtained with the preferred embodiment; Fig. 3 is an illustration of a presently preferred configuration for the lethality enhancing objects; Fig. 4 is a cross-sectional view along a portion of the longitudinal axis of the missile of Fig. 1 illustrating a preferred embodiment of the present invention; Fig. 5 is a cross-sectional view taken along line 5-5 in Fig. 4 for a first version of the preferred embodiment; Fig. 6 is a cross-sectional view taken along line 5-5 in Fig. 4 for a second version of the preferred embodiment; and Fig. 7 is a cross-sectional view taken along line 5-5 in Fig. 4 for a third version of the preferred embodiment. DETAILED DESCRIPTION Referring now to FIG. 1, the interceptor missile 11 comprises a guidance section 12, a warhead section 13, and a rocket propulsion section 14 joined together along the longitudinal axis 15 (FIG. 2) of the missile 11. The guidance section 12 contains suitable guidance components, e.g., a guidance sensor, an inertial measurement unit, a guidance processor, and a guidance control unit for effecting guidance control of the missile 11, e.g., by positioning of aerodynamic fins or by firing attitude control rocket thrusters. The interceptor missile can be ground-launched and inertially guided by aerodynamic fins toward a predicted intercept point. In the final flight phase, the on-board guidance sensor, which can be an active radar seeker, acquires the target and provides instantaneous data to the on-board guidance processor. The guidance processor can calculate an updated predicted intercept point with the target, and can provide homing guidance signals to control the firing of small solid rocket thrusters mounted near the nose of the interceptor missile 11. The warhead section 13 is a lethality enhancing device for radially deploying a plurality of objects at a low velocity in order to achieve a predetermined pattern of the deployed objects. The propulsion section 14 can be any suitable rocket motor. The relatively small size of the interceptor missile 11 enables the missile 11 to respond rapidly to guidance commands. Each of the lethality enhancing objects 28 should have an external configuration which minimizes aerodynamically induced deviations in the path of the object during the deployment of the object. Referring now to FIG. 3, the presently preferred configuration for a lethality enhancing object 28 is a cycloid, and more specifically, a shape of a right circular cylinder 42 having a longitudinal axis 44 and a radius 46, in combination with a first convex spherical segment 48 instead of a planar surface at the first end of the right circular cylinder 42 and a second convex spherical segment 50 instead of a planar surface at the second end of the right circular cylinder 42. The spherical segment 48 of a first sphere having its center on the longitudinal axis 44 is defined by two parallel planes 52, 54 with the plane 52 being tangent to the first sphere and the distance between the two planes 52, 54 being less than or equal to the radius 56 of the first sphere with the radius 56 of the first sphere being greater than or equal to the radial dimension 46 of the right circular cylinder 42. Similarly, the spherical segment 50 of a second sphere having its center on the longitudinal axis 44 is defined by two parallel planes 58, 60 with the plane 58 being tangent to the second sphere and the distance between the two planes 58, 60 being less than or equal to the radius 62 of the second sphere with the radius 62 of the second sphere being greater than or equal to the radial dimension 46 of the right circular cylinder 42. The lethality enhancing objects 28 are preferably positioned with their longitudinal axes at least generally parallel to the longitudinal axis 15 of the lethality enhancing device 13. In general each ratio of spherical radius to the cylindrical radius will be in the range of about 1:1 to about 10:1. However, it is presently preferred for the radius 56 of the first sphere to be equal to the radius 62 of the second sphere, and for the ratio of the spherical radius to the cylindrical radius to be in the range of about 1.1:1 to about 5:1 in order to simplify the formation of the lethality enhancing object 28 by sintering metal particles in a mold having the desired shape, such that no machining of the molded object is required. This presently preferred configuration for the lethality enhancing objects 28 permits the lethality enhancing objects 28 to be closely packed in the matrix 26 and to provide a greater total mass of the lethality enhancing objects in a given volume of objects 28 and matrix 26 than would be possible with a spherical configuration. Each lethality enhancing object 28 is preferably fabricated from a dense metal. While any suitable dense metal can be employed, metals having a density of at least 15 gm/cc are presently preferred, e.g., tantalum, tungsten, rhenium, uranium, etc. The higher densities permit a greater mass in a given volume or the same mass in a smaller volume, thereby enhancing the impact force of a lethality enhancing object 28 while decreasing the surface area exposed to aerodynamic forces. A presently preferred lethality enhancing object 28 is formed of pressed sintered particles of ductile tungsten. In general, each lethality enhancing object 28 will have a mass greater than about 50 grams, preferably greater than about 100 grams, and more preferably at least about 150 grams. In contrast, fragments from a blast fragmentation can be on the order of 1 to 10 grams. A preferred embodiment of the invention is illustrated in FIGS. 4 and 5. The lethality enhancing device 113 has an inner annular wall member 120, an annular body 122 of a low velocity explosive, an annular liner wall 124, an annular matrix 126 containing a plurality of arrays of discrete objects 28, and an annular external shell 130. Each of the inner annular wall member 120, the annular body 122, the annular liner wall 124, the annular matrix 126, and the annular external shell 130 has a central longitudinal axis which extends along the central longitudinal axis 15 of the missile 11. The inner annular wall member 120 comprises two annular wall sections 120a and 120b which are spaced along the central longitudinal axis 15, with each of the annular wall sections 120a and 120b having a substantially cylindrical outer surface, and having differing outer diameters, thus forming a stepped exterior surface for the annular wall member 120. In the illustrated embodiment, the outer diameter of the first annular wall section 120a is smaller than the outer diameter of the adjacent second annular wall section 120b. The inner annular wall 120 has an annular flange 132 which extends radially outwardly from the front edge of the forwardmost annular wall section 120a, and an annular flange 134 which extends radially outwardly from the rear edge of the rearmost annular wall section 20b. The annular flanges 132 and 134 provide reflective surfaces for explosive pressure waves in the annular body 122 of low velocity explosive. The annular liner wall 124, which is of cylindrical configuration, is positioned exteriorly of and spaced from the inner wall member 120. The annular body 122 of a low velocity explosive is positioned exteriorly of the inner wall member 120 and interiorly of the annular liner wall 124. The annular body 122 of low velocity explosive has a stepped internal configuration so as to mate with the stepped external configuration of the inner wall member 120, and a generally cylindrical external configuration so as to mate with the cylindrical inner configuration of annular liner wall 124. Accordingly, the annular body 122 fills the annular space defined by the exterior surface of the stepped portions 120a and 120b of the annular inner wall 120, the inner surface of the annular liner wall 124, the rearwardly facing surface of the annular flange 132 and a portion of the forward surface of the flange 134. Thus, in the illustrated embodiment, the annular body 122 of low velocity explosive comprises two annular explosive sections 122a and 122b, with each of the annular explosive sections being positioned coaxially with and radially exteriorly of the substantially cylindrical outer surface of a respective one of the annular wall sections 20a and 20b. Thus, the radial thickness of the annular explosive section 22a is greater than the radial thickness of the annular explosive section 122b. The lethality enhancing objects 28 are embedded in the annular matrix 126, such that the annular matrix 126 and the discrete objects 28 fill the space between the outer surface of the annular liner wall 124 and the radially adjacent inner surface of the annular external shell 130. The discrete objects 28 are arranged in two arrays 140a and 140b, which are positioned coaxially with and exteriorly of the annular body 122 of explosive at different locations along the central longitudinal axis of the missile 11, with each annular array having a circular configuration in a plane perpendicular to the longitudinal axis 15 of the missile and containing a plurality of lethality enhancing objects 28 spaced apart about the circumferntial extent of the respective array. The annular matrix 126 is formed of frangible material in order to maintain the lethality enhancing objects 28 in the desired relative positions while in the undeployed state in the lethality enhancing device 113 but which is readily broken up so as to release the lethality enhancing objects 28 upon detonation of the low velocity explosive body 122. The matrix 126 is preferably a synthetic polymeric material containing hollow glass microspheres. The hollow glass microspheres substantially reduce the weight of the matrix 126 without a prohibitive sacrifice in the structural strength of the matrix 126. The hollow glass microspheres give shock mitigation, i.e., act as shock absorbers, and reduce the surface contact of the objects 28 with the polymeric material of the matrix 126, thereby facilitating separation of the objects 28 from the matrix 126. The presence of the resin matrix between the objects 28 and the low velocity explosive material 122 provides for a slower velocity of the objects 28 when deployed. The ratio of glass microspheres to resin in the matrix 126 can be varied to obtain the desired properties, such as structural integrity prior to the detonation of the low velocity explosive body 122. If desired, the hollow microspheres can contain a reactive material, such as an incendiary material or an exothermic material, e.g., thermite. Such incendiary material or exothermic material can still be included in the matrix 126 even when the microspheres are omitted. The matrix 126 itself can be formed from a reactant materiel, e.g., polytetrafluoroethylene. If desired, the matrix 126 can be in the form of an aluminum alloy cast about the objects 28. The aluminum alloy matrix is particularly advantageous where desired flexibility includes the option of the interceptor missile being maintained intact until it impacts the target. Each annular array 140a, 140b can be embedded in a single matrix 126 to position al of the annular arrays of lethality enhancing objects 28, or each annular array can be in a respective discrete annular section of frangible matrix material. The number of annular arrays and the number of lethality enhancing objects 28 within each annular array can be varied in accordance with the size of the desired pattern of deployed lethality enhancing objects 28 and the spacing of the deployed objects 28 within the desired pattern. In the illustrated embodiment, the number of annular arrays corresponds to the number of inner wall sections and the number of annular explosive sections with each of the annular explosive sections being positioned in contact with and radially outwardly from a respective one of the annular wall sections, and each of the annular arrays being positioned coaxially whit, adjacent to and radially outwardly from a respective one of the annular explosive sections. The number of lethality enhancing objects 28 in each array can be the same or different. The lethality enhancing objects 28 in each undeployed annular array can be spaced apart at equal intervals about the circumferential extent of the respective array, or the lethality enhancing objects 28 in a particular annular array can be spaced apart at differing intervals. The objects 28 in a particular array are preferably spaced at equal centerline-to-centerline intervals. While it is possible for the positions of the lethality enhancing objects 28 in one of the annular arrays to correspond to the position of selected ones of the lethality enhancing objects 28 in another one of the annular arrays the angular intervals in each annular array can be offset from the angular intervals in the adjacent annular array in order to provide a more uniform spacing of the objects when deployed. If desired, the ends of the objects 28 in one annular array can fit between the ends of the objects 28 in an adjacent annular array in order to reduce the total axial length required by the annular arrays 140a and 140b. In general, the lethality enhancing objects 28 in a particular ring or array will be deployed in a circular pattern, with the lethality enhancing objects 28 of the array having the fastest deployment velocity forming a large diameter circular pattern, while the lethality enhancing objects 28 of the array having the slowest deployment velocity form a small diameter circular pattern, thereby forming a composite pattern f concentric circular arrays of deployed lethality enhancing objects 28. In the illustrated embodiment, the array 140a contains twelve lethality enhancing objects 28 spaced at equal centerline-to-centerline intervals of approximately 30°, while the array 140b also contains twelve lethality enhancing objects 28 spaced at equal centerline-to-centerline intervals of approximately 30°, with the lethality enhancing objects 28 in the array 140a being offset form the lethality enhancing objects 28 in the array 140b by approximately 15°. In the embodiment illustrated in FIGS. 4 and 5, the annular explosive sections 122a and 122b have substantially different radial thicknesses. Assuming a uniform concentration of the low velocity explosive in the annular body 122 of explosive, then the amount of the low velocity explosive in the annular explosive section 122a in radial alignment with the first annular array 140a is substantially greater than the amount of the low velocity explosive in the second annular explosive section 122b in radial alignment with the second annular array 140b. Thus, each of the annular explosive sections 122a and 122b can have an amount of low velocity explosive which is different from the amount of the velocity explosive in the other annular explosive section. With each of the arrays 140a and 140b containing the same number of objects 28, the amount of energy provided to each of the plurality of objects 28 in the first annular array 140a by the amount of the low velocity explosive in the first annular explosive section 122a would be greater than the amount of energy provided to each of the plurality of objects 28 in the second annular array 140b by the amount of the low velocity explosive in the second annular explosive section 122b. However, the variation in energy provided the lethality enhancing objects 28 individually can also be achieved by varying the mass of the lethality enhancing objects 28, varying the composition of the low velocity explosive body 122 adjacent the annular arrays 140a and 140b, and/or by varying the thickness and/or rigidity of the inner wall 120 along its longitudinal axial length and thereby varying the implosion resistance of inner wall 120 from a location adjacent the first annular array 140a to a location adjacent the second annular array 140b. An annular booster ring 166 is positioned coaxially with and radially inwardly of the first annular wall section 120a, so as to be substantially enclosed within the central chamber 180 formed by the inner wall 120. This configuration permits a reduction in the longitudinal length of the warhead section 13. The annular wall section 120a is provided with a plurality of holes 168 which extend at least substantially radially therethrough and which are spaced apart from each other in a circular configuration so that the first annular explosive section 122a is exposed to each of the holes 168. Any suitable number of holes 168 can be employed, preferably positioned at equally spaced intervals in the circular configuration. Each hole 168 contains an initiator pellet 70 surrounded by an annular plastic support 72. The annular booster ring 166 overlies each of the holes 168 so as to cause the initiator pellets 70 to contact both the booster ring 166 and the annular body 122 of low velocity explosive. Thus, the booster ring 166 is positioned in proximity to the forwardmost first annular explosive section 122a so as to initially fire the forwardmost first annular explosive section 122a. The booster ring 166 can be similar to the booster ring 66 except for its position. A safe arm fuze 190, which can be a single safe arm fuze or a combination of two or more safe arm fuzes, can be positioned coaxially with and radially inwardly of the second annular wall section 120b, so as to be substantially enclosed within the central chamber 180 formed by the inner wall 120. If desired, the safe arm fuze 190 can be encased in a shock attenuating foam material 194. In the embodiment of FIG. 5, the number of holes 168 equals the number of objects 28 in the first array 140a. The holes 168 are spaced at approximately 30° intervals about the circumference of the first annular wall section 120a, and are offset with respect to the objects 28 in the first array 140a such that each hole 168 is in radial alignment with a point approximately midway between a respective pair of objects 28 in the first array 140a. This arrangement provides for equal energy levels to be imparted to the objects in the forwardmost array. However, other configurations can be employed. Thus, the embodiment of FIG. 6 has twelve holes 168, each of which is in radial alignment with a respective one of the twelve objects 28 in the first array 140a. This arrangement also provides for equal energy levels to be imparted to the objects in the forwardmost array. The embodiment of FIG. 7 has eight holes 168 spaced apart at 45° intervals, with four of the holes 168 being in axial alignment with a respective one of the twelve objects 28 in the first array 140a while the other four holes are in radial alignment with a point approximately midway between a respective pair of the objects 28 which are not in radial alignment with a hole 168. This arrangement provides for a higher energy level to be imparted to each of the radially aligned objects 28 in the forwardmost array in comparison to the energy level imparted to the objects 28 which are not radially aligned with a hole 168. While each of the annular explosive sections 122a and 122b can be a continuous uninterrupted ring of explosive material, it is possible for one or both of the annular explosive sections 122a and 122b to comprise a plurality of individual annular segments spaced apart from each other about the circumference of the annular explosive section, as illustrated in FIG. 6. This configuration permits a savings in the amount of low explosive material when the objects in the radially adjacent array are spaced apart a significant distance. When the first annular explosive section 122a is a continuous uninterrupted ring of explosive material, the second annular explosive section 122b can comprise the spaced discrete segments, in order to provide a reduced amount of explosive material for each object 28 in the second array 122b as compared to the objects 28 in the first array 122a, even though the first and second annular explosive sections 122a and 122b have the same radial thickness. FIG. 2 is a representation of the radial deployment of the lethality enhancing objects 28, in a plane perpendicular to the line of flight of the missile 11, by the warhead embodiment of FIGS. 4 and 5, wherein the twelve objects 28 of the first array 140a have been dispersed at a higher velocity than the twelve objects 28 of the second array 140b so that the objects 28 in the deployed first array 140a form a circle having a greater radius than the circle formed by the objects 28 in the deployed second array 140b. The annular body 22 or 122 of low velocity explosive should have a low velocity of detonation so that the radial deployment of the lethality enhancing objects 28 occurs at a relatively low velocity without deformation of the lethality enhancing objects 28 from the low velocity explosive forces. Any suitable low velocity explosive can be employed to form the annular body 22 or 122. While a detonation velocity less than about 6000 meters per second is generally considered to be a low detonation velocity value, the detonation velocity of the annular body 22 or 122 will generally be less than 5500 meters per second and will preferably be less than 5000 meters per second, and will more preferably be less than 4000 meters per second. The resulting radial deployment velocity of the objects 28 will generally be less than about 304,8m (1000 feet) per second, preferably less than about 182,4m (600 feet) per second, and more preferably less than about 152m (500 feet) per second. In contrast, granular, cast, or crystal TNT has a detonation velocity substantially in excess of 6000 meters per second, the speed of the interceptor missile 11 towards its target can exceed 1520m (5000 feet) per second, and the speed of fragments resulting from a blast-fragmentation will normally be greater than 912m (3000 feet) per second. The special welding powder #6B, available from Trojan Corporation, Spanish Fork, Utah, has been employed in a loose powder form as a low velocity explosive for this type of warhead. Similarly, a low velocity explosive material comprising a polymeric matrix, to facilitate handling of the annular body 43 and to avoid any shifting of a powder explosive, has been employed. Thus an explosive composition of pentaerythrol tetranitrate (PETN) in an elastomer, such as silicon rubber, has been found to be useful. The amount of PETN in such composition will generally be in the range of about 10 to about 30 weight percent, preferably in the range of about 20 to about 25 weight percent, with the amount of the elastomer being in the range of about 90 to about 70 weight percent, preferably in the range of about 80 to about 75 weight percent. However, in accordance with an aspect of the present invention, it is desirable that the low velocity explosive contain a foaming agent in order to achieve the desired combination of detonation pressure, energy, and explosive thickness. In general the annular body 22 or 122 will have a density of less than about 1.2 g/cm 3 , and preferably less than about 1.1 g/cm 3 . The low density of the annular body 22 or 122 reduces stress on the objects 28, and permits volume variations due to dimensional tolerances of the mold without causing significant changes in explosive energy. The presently preferred low explosive composition is formed by mixing a liquid explosive, a powder explosive, and a liquid polymerizable material containing a foaming agent, such that the liquid explosive acts to reduce the viscosity of the resulting mixture. A liquid polymerization catalyst is added to the mixture just prior to the injection of the mixture into a mold to produce a rigid foam. An exemplary composition comprises trimethylolethane trinitrate (TMETN), PETN, liquid (CO 2 -blown) polyurethane foam, and an isocyanate catalyst. In general, the amount of low velocity explosive incorporated in the composition is a function of the thickness of the ring of low velocity explosive required for the lowest object deployment velocity. The minimum low velocity explosive thickness that will detonate is inversely proportional to the weight percentage of the low velocity explosive in the composite material. The use of low deployment velocities for the lethality enhancing objects 28 reduces the amount of low velocity explosive material needed to produce the desired pattern, as well as eliminates a need for a very sensitive firing system which would be required for use with high velocity fragments. Reasonable variation and modifications are possible within the scope of the appended claims to the invention. For example, any suitable number of arrays of lethality enhancing objects can be employed. The mass of the lethality enhancing objects can vary within an array and from array to array. In order to adjust the direction of deployment of a lethality enhancing object, the lethality enhancing object can be positioned with its longitudinal axis at an angle to the longitudinal axis of the missile, the explosive body can be positioned at an angle to the longitudinal axis of the missile, and/or the location of the initial detonation points can be varied.

Claims: A device for radially deploying a plurality of objects (28) from a warhead capable of moving at high velocity, said device comprising: an inner annular wall member (120) having a central longitudinal axis; an annular shaped body (122) of explosive formed by a continuous uninterrupted ring of explosive or by spaced individual annular segments of explosive, said annular body (122), having a central longitudinal axis, said annular body (122) being positioned exteriorly of said inner annular wall member (120) with the central longitudinal axis of said annular body extending at least substantially along the central longitudinal axis of said inner annular wall member; a plurality of annular arrays (140a, 140b) positioned coaxially with and exteriorly of said annular body (122) at different locations along the central longitudinal axis of said annular body (122), each of said annular arrays comprising a plurality of objects (28) positioned at spaced locations about the circumference of the respective annular array; and a booster (166) positioned in proximity to said annular body (122) so as to detonate said annular body, said booster (166) being positioned radially inwardly of said inner annular wall member (120); and wherein said inner annular wall member (120) contains a plurality of holes (168) extending at least generally radially therethrough to expose said annular body (122) of explosive to detonation of said booster; characterised in that said annular body (122) is a body of a low detonation velocity explosive having a detonation velocity of less than 6000 m/s; said booster has the shape of a booster ring (166); a forwardmost, first array (140a) of said plurality of annular arrays (140a, 140b) is positioned generally radially outwardly of said plurality of holes (168); and that said plurality of holes (168) comprises a first group of holes at spaced locations about the circumference of said inner annular wall member (120) with each of said first group of holes (168) being positioned in radial alignment with a respective one of the objects (28) of said first array (140a). Device in accordance with claim 1, wherein said plurality of holes (168) further comprises a second group of holes at spaced locations about the circumference of said inner annular wall member (120) with each of said second group of holes being positioned in radial alignment with an intermediate point between a respective pair of the objects (28) of said first annular array (140a). Device in accordance with claim 2, characterised in that each of said second group of holes (168) is positioned in radial alignment with a midpoint between a respective pair of the objects (28) of said first array (140a), and in that each respective pair of objects in said first angular array is positioned between two of the objects (28) of said first annular array which are in radial alignment with two of said first group of holes (168). A device for radially deploying a plurality of objects (28) from a warhead capable of moving at high vecocity, said device comprising: an inner annular wall member (120) having a central longitudinal axis; an annular shaped body (122) of explosive formed by a continuous uninterrupted ring of explosive or by spaced individual annular segments of explosive, said annular body (122), having a central longitudinal axis, said annular body (122) being positioned exteriorly of said inner annular wall member (120) with the central longitudinal axis of said annular body extending at least substantially along the central longitudinal axis of said inner annular wall member; a plurality of annular arrays (140a, 140b) positioned coaxially with and exteriorly of said annular body (122) at different locations along the central longitudinal axis of said annular body (122), each of said annular arrays comprising a plurality of objects (28) positioned at spaced locations about the circumference of the respective annular array; and a booster (166) positioned in proximity to said annular body (122) so as to detonate said annular body, said booster (166) being positioned radially inwardly of said inner annular wall member (120); and wherein said inner annular wall member (120) contains a plurality of holes (168) extending at least generally radially therethrough to expose said annular body (122) of explosive to detonation of said booster; characterised in that said annular body (122) is a body of low detonation velocity explosive, having a detonation velocity of less than 6000 m/s; said booster (166) has the shape of the booster ring; a first array (140a) of said plurality of annular arrays (140a, 140b) is positioned generally radially outwardly of said plurality of holes (168); and each of said plurality of holes (168) is positioned so as not to be in radial alignment with any of the objects (28) of said first annular array (140a). Device in accordance with one of the claims 1 to 4, characterised in that said inner annular wall member (120) comprises a plurality of annular wall sections spaced along said central longitudinal axis, each of said annular wall sections having a substantially cylindrical outer surface, with adjacent annular wall sections having differing outer diameters; said annular body of low detonation velocity explosive comprises a plurality of annular explosive sections (122a,122b), each of said annular explosive sections being positioned coaxially with and exteriorly of the substantially cylindrical outer surface of a respective one of said annular wall sections mating therewith; and a forwardmost one of said plurality of angular wall sections contains said plurality of holes (168) to expose the forwardmost first annular explosive section to detonation of said booster ring (166). Device in accordance with claim 5, characterised by further comprising a safe arm fuze for said booster ring (166), said safe arm fuze being positioned radially inwardly of a inner annular wall section located adjacent said forwardmost inner annular wall section. Device in accordance with claim 5, characterised in that it comprises first and second safe arm fuzes for said booster ring (166), said first and second safe arm fuzes (190) being encased in shock-attenuating foam (194). Device in accordance with claim 5, characterised in that said plurality of annular arrays (140a, 140b) consists of two arrays, and that said forwardmost first annular explosive section (122a) contains an amount of said low detonation velocity explosive which is greater than the amount of said low detonation velocity explosive in the second annular explosive section (122b). Device in accordance with one of the claims 1 to 8, wherein said inner annular wall member (120) is formed of metal. Device in accordance with one of the claims 5 to 9, characterised in that at least one of said annular explosive sections (122) comprises a plurality of segments of explosive material spaced apart from each other about the circumference of said annular body. Device in accordance with claim 5, characterised in that the energy provided by said forwardmost first annular explosive section to each of the objects in said forwardmost first annular array is less than the energy provided by said second annular explosive section to each of the objects in the second annular array. Device in accordance with claim 11, characterised in that said second annular explosive section contains an amount of said low detonation velocity explosive which is greater than the amount of said low detonation velocity explosive in the forwardmost first annular explosive section. Device in accordance with claim 12, characterised in that said plurality of annular arrays comprises at least three annular arrays. Device in accordance with claim 13, characterised in that the (a) third annular explosive section contains an amount of said low detonation velocity explosive which is less than the amount of said low detonation velocity explosive in the forwardmost first annular explosive section. Device in accordance with one of the claims 1 to 14, characterized in that each of said holes (168) contains an initiator pellet (70). Device in accordance with claim 15, characterized in that each initiator pellet (70) is surrounded by an annular plastic support (72). Device in accordance with claims 15 or 16, characterized in that each initiator pellet (70) contact both said booster ring (166) and said annular body (122).

Inventors: CRADDOCK GERALD GRAVES, CRUISE ELMER C, CRADDOCK, GERALD GRAVES, CRUISE, ELMER C.
Applicants: LORAL VOUGHT SYSTEMS CORP, LORAL VOUGHT SYSTEMS CORPORATION
Application year: 1996
Main classification: F42B12
IPC codes: F42B12