Directed warhead
United States Patent Kupelian DIRECTED WARHEAD Primary Examiner-Benjamin A. Borchelt Assistant Examiner-H. J. Tudor [75] Inventor: Vahey S. Kupelian, Chevy Chase,  
 Md gttolzrfiey, Agegflzr IIzrlrlnR. S. Sc1asc1a; C.  
  un ouser; e er [73] Assignee: The United States of America as represented by the Secretary of the EXEMPLARY CLAIM Navy, Washington, DC. 1. A directed warhead comprising in combination a missile, an explosive charge carried by said missile, a [22] Flled 1960 casing for said charge, associated means for weaken- [21] Appl. No.: 45,766 ing determinable sectors of said casing, signal generating target detection and direction determining means 52 U.S. c1 102/67; 102/702 P; 102/1310. 2 carried saidfnissile means. carried by said. missile [51] Int. Cl. F42b 13/48 re.spor.lswe to i from Sald target. detection and [58] Field of Search 102/67 68 69 50 702 R d1rect1on determming means for actuating at least one 102/70 P 244/141: of said sector weakening means, and means for detonatmg said exploslve charge in timed relationship with the actuation of said sector weakenin means whereb [56] References cued a signal from said target detection an? direction deter UNITED STATES PATENTS mining means will actuate said sector weakening 2,137,436 11/1938 Barnhart 102/69 X means in timed relationship to the detonation of said Pierce X explosive charge creating a maximized explosive effect Sector Selector in the direction of said weakened sector and a target.  
 6 Claims, 4 Drawing Figures (iv/dance Sysfam Proxlmiiy Device PATENTEDAPR 1 5:975 3.871376 sum 1 or 2 Secfar Se/ector Guidance System 1N VENTOR Value .5. Kupe/ian Proximi/y Devi ca 12 ATTORNEYS DIRECTED WARHEAD The invention described herein may be manufac tured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalty thereon or therefor.  
  This invention relates to a warhead and more particularly to a warhead with a directed fragmentation pattern which results in a great destructive effect in a dcterminable direction.  
  The development of a projectile suitable for use against rapidly moving targets such as aircraft has long presented a serious problem as the increasing speed and altitude at which modern aircraft fly has made the possibility of obtaining a direct hit with an antiaircraft gun very remote. Often many thousands of rounds are fired. by defending personnel. at an aircraft before any hits are scored. The development of missiles which fly at altitudes of hundreds of miles and at speeds of thousands of miles per hour has increased many times the complexity of this already difficult problem. One can readily appreciate that the probability of obtaining a direct hit when firing at an intercontinental ballistic missile or even some modern jet aircraft is very remote.  
  Prior to World War ll the only known Way to defend against an enemy aircraft was to shoot at it with antiaircraft artillery in the hope of obtaining a direct hit. or to Send up a defensive aircraft which would be provided with cannon or machine guns to fire at the attacker. The latter method was essentially a means of positioning a gun closer to the target in the hope of increasing the chance of obtaining a lethal hit. Attempts were made to place a timed fuze in anti-aircraft shells. to obviate the need for obtaining a direct hit, in the hope that the explosion of the shell in the general area of the target would destroy it by either blast or fragmentation effects. However, it was necessary to know the range of the target, the course being flown by the target, and the velocity of both the target and shell with great accuracy in order to cause the explosion to occur within the small time interval in which the shell was passing the target.  
  The development of the proximity fuze resulted in a weapon capable of much greater effect, however, this was by no means the answer to all the problems facing those engaged in air defense. It has always been desirable-to obtain a more sensitive fuze or a shell with greater destructive force, or some combination of these two. However, the destructive force of shells was generally limited by the amount of steel and explosive that a gun could throw into the air. The fuze could, of course, do nothing more than explode the shell at the point in its path which was closest to the target, although when considering the limitations placed on the destructive radius by the upper limit that must be placed on the explosive charge this might still prove ineffective.  
  The development of the self-propelled missile as an anti-aircraft weapon greatly increased the probability of hitting a moving a target because a weapon of this nature was susceptible of control or guidance during flight and thus did not depend on what might be an inaccurately determined ballastic trajectory. Present missiles can be designed to have under certain circumstances, a very high kill probability as the weapon is capable of carrying its own guidance mechanism which will guide the warhead directly to the target. If the missile is as maneuverable as the aircraft, the possibility of escape by evasive action is very small. The degree of effectiveness is greatest, due to the lower relative speed, when firing at the rear of an aircraft such as is often the case when a fighter type aircraft gets behind the target and fires an air-to-air missile.  
  However, when anti-aircraft defenses on the ground or on shipboard fire at an intruder they usually must attack from a generally head-on direction. A modern aircraft which may fly at 1,000 mph often will have a closure rate with the defensive missile as high as 3,000 mph. It will be appreciated that only small corrections may be made in the path of the missile prior to the time it has passed the target. Another factor complicating the problem is the type of guidance utilized on many missiles used for air defense operations. Due to the heat emitted from a jet aircraft, a target seeking system, using infra red radiation from the target as an information source, is very commonly employed. When approaching from the front of the target the amount of radiation received by the missile is small and therefore it is usual to employ a radio beam to guide the missile to the general area of the target and then use the infra red system for terminal guidance. This, it will be realized, reduces the time the homing system of a missile has to correct its course so as to effectuate a direct hit.  
  These difficulties force missile designers to resort to the methods used by the artillery science to increase the probability of a kill without a direct hit. The use of a proximity fuze will enable a near miss to result in considerable target damage provided enough explosive is carried by the weapon to create a blast and shrapnel effect sufficient to reach the target. However. the size restrictions placed on the smaller type missiles prevent the inclusion of enough explosive to give a large lethal radius. The detonation of a warhead in the proximity of a target results in considerable wasted energy as the conventional warhead construction produces a symmetrical blast effect on detonation, while, the target will only occupy a sector ofa few degrees in width. The remainder of the blast effect will be wasted on empty space and only a small percentage of the destructive force is directed against the target that is under attack. Although the foregoing disadvantages have been described with reference to the problem of intercepting an aircraft or missile, it will be appreciated by one skilled in the art that the same disadvantages are pres ent during an attack on a submarine or any other mobile body. Also, when a projectile is fired over enemy troops, it would be desirable to direct the blast effect in a downward direction so that the maximum destruction of ground personnel would result.  
 Hence, the problem has been to discover a method that would enable a greater portion of the explosion to be directed toward the target. The solution of this problem would enable a smaller warhead to be employed, with the attendant increase in missile range, for a given lethal force, or, conversely a greater force to be produced for a given warhead size.  
  It has been recognized that such a system should be compatable with existing missile guidance systems and should not be dependent on preset information. The system should be dependent only on information derived from the self-contained guidance system so as to remove all launching errors from the operation.  
  Accordingly, it is an object of this invention to increase the destructive radius of a warhead.  
  It is also an object of this invention to provide a warhead with a directed explosive effect.  
  It is another object of this invention to provide a warhead with a blast effect maximized in the direction of a target.  
  It is yet another object of this invention to provide a small fragmentation type warhead suitable for use in an anti-air missile.  
  Still another object of the present invention resides in the provision of a directed warhead operable without preset information on the target orientation relative to the missile.  
  Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:  
  FIG. 1 is a diagrammatic view of the instant invention in operation;  
  FIG. 2 is a diagrammatic view of one embodiment of the instant invention including a sectional view taken through the warhead;  
  FIG. 3 is a diagrammatic view of a second embodiment of the instant invention including a sectional view taken through the warhead;  
  FIG. 4 is a schematic drawing of the sector selector circuit.  
  Briefly, the present invention comprehends a projectile or warhead carrying missile and associated means for selectively weakening a segment of the projectile or warhead casing so that the force of the explosion will be directed through, and in the direction of, the weakened side. A target sensing means carried by the missile, normally the missile guidance system, is used to determine the radial direction of the target relative to the missile at the point of closest proximity thereto. This information is utilized to control the weakening of the periphery of the warhead casing in a determinable sector immediately prior to detonation of the explosive charge. The casing may be weakened by utilizing any ofa number of methods, two of which will be described in detail hereinafter. The blast effect will be concentrated in a radial direction through the weakened sector thus increasing the destructive force in the target direction. Detonation of the main charge will collapse the wall of the weakened sector prior to the fragmentation of the remainder of the casing. This sequential fragmentation will tend to direct the major portion of the explosive force in a radial direction, passing through the weakened wall section, thus increasing the destructive force in the target direction.  
  Referring now to FIG. 1 wherein an application of the instant invention to an anti-aircraft missile is shown, a missile 10, which may be fired from the ground or from another aircraft, is illustrated in proximity to a target aircraft 11. The missile is equipped with target sensing apparatus which will determine the radial direction of the enemy aircraft. By means to be described hereinafter, this information will control the weakening of a sector of the warhead casing, which weakened sector will be the sector nearest to and in line with the target aircraft. The immediately subsequent detonation of the warhead will result in a distorted blast effect which will be maximized in the direction of the target, thus increasing the probability of target destruction.  
  The information required to determine the position of the target relative to the missile, which determines the sector to be weakened, is obtained by any ofa number of well-known means such as, but not limited to, radar or infra red sensing devices. A conventional target seeking missile includes sensing means which will detect the position of the target and, through suitable electronic equipment, will generate error signals which may be used to control either deflection surfaces in the rocket exhaust or airfoil surfaces, as may be desired. These same signals are used by the present invention to control the sector weakening so that a minimum of additional circuitry is required.  
  The error signal includes both horizontal and vertical informational components which are sufficient to determine the quadrant in which the target lies. For example, if the guidance system indicates a climbing turn to the right for a direct hit, then the target is in the upper right hand quadrant and this quadrant is weakened in order to give a blast effect with a maximum destructive force in the target direction.  
  It should be understood that the embodiment described herein utilizes four quadrants of each to determine the location of the target relative to the missile, however, one skilled in the art will realize that the instant invention comprehends a greater or lesser number of sectors. The choice of four sectors is made for purposes of simplicity and clarity.  
  Referring to FIG. 2, an embodiment of the instant invention is illustrated in conjunction with one means of weakening a selected wall sector of the warhead. A warhead casing 12 which may form a portion of the wall section of a missile is shown in cross section with a suitable explosive charge 13 contained therein. A detonator 14 is provided to ignite the explosive charge 13, which is connected through cable 15 to a timing fuze l6. Fuze 16 is in turn connected through cable 17, to a quadrant selector device 40, which is carried by the missile. Around the periphery of the missile and contained within casing 12 are positioned a plurality of small explosive charge groups 19, 20, 21 and 22. Each of these charge groups is composed of a number of separate charge units electrically connected together so that all the charges in one group may be detonated simultaneously. Each of the charge groups is located in a discrete sector of the warhead casing. For example, charge group 19 is located in the upper right quadrant of the casing. While these charges are only shown in two dimensions, it is to be understood that they may extend throughout the length of the warhead casing. Each charge group is connected to the quadrant selector system 40 through separate cables 23, 24, 25 and 26. The quadrant selector system, which will be described more fully hereinafter, is connected through cable 33 and 34 to guidance system 35 and through cable 18 to a proximity or target sensing device 19 which may be any of a number of well-known types and is used to determine the point in space at which the detonation should occur. The detonation of one or more of the charge groups 19, 20, 21 or 22 a few milliseconds prior to the detonation of the main explosive charge 13 will result in an explosion with a greater portion of the blast effect directed through the weakened sector.  
  An alternative method for weakening the wall sections of the warhead is disclosed in FIG. 3 wherein the warhead casing 12 is separated from the main explosive charge 13 by an insulating material 27. The insulating material is formed to provide an inner casing approximately coaxial with the warhead casing. Longitudinal ribs 28 are provided to keep the casings apart and to separate the space into discrete quadrants. The spaces 29, 30, 31 and 32, which correspond to the explosive charge groups of the previously described embodiment are filled with a material such as thermite, or any similar substance, which has a high burning temperature. When it is desired to weaken a sector of the warhead, a signal is applied to one or more of ignitors 50 in the appropriate quadrant through any of connectors 23, 24, or 26 by the sector selector 40 which will ignite the thermite. The resultant heat will cause a reduction in the wall strength of the warhead casing in the desired area.  
  The insulation material is required to have only thickness enough to withstand the intense heat for a very short period of time, as the warhead charge is detonated only a few milliseconds after the thermite is ignited. The warhead shell, being of metallic construction, is a good conductor of heat and will experience a rapid temperature rise with a resulting structural weakness. Thus, the following detonation of the warhead results in a greater blast effect in the direction of, and directed through, the weakened casing area.  
  The missile receives two types of information as it closes on a target, that received from the guidance system, which includes the horizontal and vertical directional correction signals, and that received from the proximity sensing device. which, in general consists of a voltage or similar indication inversely proportional to the distance separating the missile and the target. These two types of information are utilized by the selector system to perform two separate and distinct functions. The guidance signals are utilized, through appropriate circuitry, to continuously select a quadrant of the warhead casing that is in line with the target, if the missile were to pass the target with the particular course error then existing. A  
  Thus as the missile changes direction, to follow any evasive action of the target, it may be to the left or right, above or below, the target at any given instant of time, however, first one sector is selected and then an other so that when the missile comes within the range of the target the proper quadrant is continuously connected, through the selector system, to the proximity sensing device. As the missile approaches the target, the proximity device senses the presence of the target and generates a signal which, through the selector system causes the proper sector charges to detonate just prior to the ignition, by the fuse, of the main charge.  
  The selector circuit, illustrated in FIG. 4, is provided to determine from the guidance system output which of the charge groups should be detonated to provide an explosion directed at a particular target. This circuit utilizes two polarized relays 36 and 37 and is designed to operate on a typical guidance system output consisting of two voltages. One of the voltages partially indicates flight path error by a positive or negative signal, depending on whether the target is above or below the missile flight path. The second voltage completely determines the flight path error by positive or negative signals depending on theposition of the target to the right or left of the missile. These two voltages are used to control the position of the polarized relays which are of the three-position type, having a normally closed central contact and first and second normally open contacts which will close respectively on the application of a positive or negative voltage. It is to be understood that the particular circuitry illustrated could be modified in any of a number of ways well-known in the computer art without departing from the spirit of the present invention.  
  One of the polarized relays 36, having five contact sections, has its coil connected at contact 38 through cable 33 to the vertical error signal from the missile guidance system and will exhibit one of three conditions. When no vertical error signal is present, the relay is in the center position. A positive signal, which for purposes of illustration, is taken to be an upward correction, energizes the relay in one direction, shown as the upper position, while a negative signal energizes the relay in the opposite direction. A similar relay 37 having three contact sections has its coil connected at contact 39 through cable 34 to the horizontal error signal. The operation of relay 37 is the same as that of relay 36 with a right error signal being positive and illustrated in FIG. 4 as the right hand position, while the left signal is negative and shown as the left hand position. For simplicity of illustration, the various sections or poles of each relay are referred to by the reference numeral assigned to the moving contact member.  
  Considering first the relay 37, which is controlled by the horizontal error signal, it will be observed that contacts 59 and 61 of section 51 are not used. Contact is connected to contacts 62 and 64 of section 52. Proximity device 19, which generates the signal controlling detonation of the sector charges and the main warhead, is also connected to contact 62 of section 52 and to the fuse through cable 17. Contact 63 is connected to contact 65 and the relay arm of section 57 on the vertical relay. Contacts 66 and 67 are tied together ano connected to the relay arm of section 56 on the vertical relay. The relay arm 51 is connected to relay arm 54 on the vertical relay and the relay arms 52 and 53 are tied together and connected to contacts 68 and 70 of section 54 on the vertical relay.  
  Contacts 71 and 73 of section 55 of the vertical relay are not used while contact 72 of&#39;this section is connected to contact 74 and 75 of section 56 and the lower right sector charge through cable 24. Relay arm 55 is connected to contact 76 of sections 56 and to the upper right sector charge through cable 23. Contacts 77 and 78 of section 57 are tied together and connected to the relay arm of section 58 and to the lower right sector charge through cable 25. Contact 79 of section 57 is connected to contact 81 of sections 58 and to the upper left sector charge through cable 26. Contacts and 82 of section 58 are not used.  
  It will be observed that the operation of the sector selector relays is such that one or more sector charges are connected to the proximity device at all times so that a detonating impulse occurring at any time causes the proper sectors to detonate. The construction of the sector selector is such that a target located within one quadrant causes the sector charge in that quadrant to detonate while a target on the line between two sectors causes the two sectors adjacent that line to detonate. If no error signal is present, i.e., a target directly ahead, all four sector charges detonate. It is to be understood that reference to a sector as being upper or lower, or left or right, is relative to the missile and not to the earth or any fixed reference plane. In normal operation, the missile may rotate in flight and the coordinate system referred to rotates with the missile.  
  An example of the sector selector system in operation will be described when a target is in the lower right sector. As the missile passes the target within lethal range, the proximity device will generate a detonating signal that will be applied simultaneously to the fuse 60 through cable 17 and to contact 62 of the horizontal selector relay. For the assumed target positions the guidance error signals will energize the vertical relay to the lower position and the horizontal relay to the right hand position. The signal applied to contact 62 will pass through the connection to contact 64, through relay arm 52 to relay arm 53, through relay arm 53 to contact 67, thence to relay arm 56 ofthe vertical relay, from relay arm 56 to contact 74 and then to the lower right sector charge through cable 24. Similar circuits may be traced for the other possible target positions, as described hereinbefore.  
  The overall operation of the system may be summarized by considering the cycle of operation as the mis sile approaches a target. Two types of information are received by the missile at all times. guidance signals which correct the flight path and a proximity signal, which by its presence or absence indicates whether or not a target is within lethal range. The guidance signals, in addition to controlling the flight path, are continuously fed to the sector selection relays 36 and 37, which, in response to course error signals, continuously connect the proper sector of the warhead casing. closest to the target from the projected flight path at that instant of time. to the proximity device. when a target comes within range. the proximity device generates a signal which through the sector selector circuit ignites the proper sector charges, if an explosive method is used for weakening the walls. At the same time the proximity signal is applied to the fuse 16 which after a very short time delay, dependant on the method used to weaken the casing wall, causes the igniter to deto nate the main warhead 13.  
  The time delay in the warhead detonation is selected to equal the time required for weakening the walls of the determined sector. The resultant explosion is directed so that the blast effect is maximized in the direction of the weakened sector and thus the effective lethal range of the missile is increased for a given warhead size.  
  Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.  
 What is claimed is:  
  l. A directed warhead comprising in combination a missile. an explosive charge carried by said missile, a casing for said charge, associated means for weakening determinable sectors of said casing, signal generating target detection and direction determining means carried by said missile, means carried by said missile responsive to signals from said target detection and direction determining means for actuating at least one of said sector weakening means, and means for detonating said explosive charge in timed relationship with the actuation of said sector weakening means whereby a signal from said target detection and direction determining means will actuate said sector weakening means in timed relationship to the detonation of said explosive charge creating a maximized explosive effect in the direction of said weakened sector and a target.  
  2. A directed warhead comprising in combination an explosive device. a container for said explosive device, a plurality of spaced explosive charges imbedded in said container, means for selectively detonating said spaced explosive charges, and means for detonating said explosive device in timed relationship with the detonation of said spaced explosive charges whereby the explosion of said device will have a maximized effect in a radial direction through said detonated spaced charges.  
  3. A directed warhead comprising in combination an explosive device, a container for said device, a plurality of spaced explosive charges for weakening selective portions of said container, means responsive to external stimuli for selectively detonating said spaced explosive charges, and means for detonating said explosive device in timed relationship with the detonation of said spaced explosive charges whereby the explosive force of said device will be maximized through said weakened sector and in the direction of said external stimuli.  
  4. A directed warhead detonating system comprising in combination a missile, an explosive device, a container for said explosive device, a pluralityof explosive charges imbedded in spaced sectors of the walls of said container, signal generating target detection and direction determining means carried by said missile, sector selection means responsive to said signals generated by said target detection and direction determining means carried by said missile, and means carried by said missile for detonating said explosive device in timed relationship with the explosion of said spaced sector charges whereby a signal from said target detection and direction determining means will actuate said sector selection means and in turn detonate both the charges contained in at least one of said selected sectors of said container and said explosive device in timed relationship creating a maximized explosive effect in the direction of said detonated charges and a target.  
  5. A directed warhead detonating system comprising in combination a missile, an explosive device, a container for said explosive device, a plurality of combustible elements positioned in contact with the inner surface of said container, insulation means separating said combustible elements from each other and from said explosive device, signal generating target detection and direction determining means carried by said missile. associated means responsive to said signals generated by said target detection and direction determining means for selectively igniting at least one of said combustible elements to weaken a sector of said container, and means carried by said missile for detonating said explosive device in timed relationship with the ignition of said combustible elements whereby the explosion of said device will have a maximized effect in the direction of said weakened sector.  
  6. A directed. warhead detonating system comprising in combination a missile, an explosive warhead carried by said missile, a casing for said warhead, means for detonating said warhead, a plurality of independently detonatable explosive charges imbedded in spaced sectors of said casing, a signal generating proximity device and a signal generating target direction determining means carried by said missile, means responsive to said target direction determining means for selecting the sectors of said missile nearest to said target, and means 10 charges contained in at least one of the selected sectors of said casing and the warhead in timed relationship creating a maximized explosive effect in the direction of said weakened sector toward a target.