Patent Publication Number: US-9903692-B2

Title: Method and device for controlling the power type and power emission of a warhead

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Patent Application DE 10 2015 010 274.5 filed Aug. 8, 2015, the entire disclosure of which is incorporated by reference herein. 
     TECHNICAL FIELD 
     The disclosure herein relates to a method for controlling the power type and power emission of a cylindrical warhead comprising at least two ignition devices, the first of which is arranged in the region of one of the head sides and the second of which is arranged in the region around the center of the longitudinal axis of the warhead, and which are triggered either individually or at a selectable interval of time, exhibiting a cylindrical explosive charge with a tubular perforated mask surrounding the explosive charge, and comprising a splinter-forming casing surrounding the perforated mask. 
     BACKGROUND 
     Standard pressure (or more commonly referred to as “blast”)/splinter charges with an explosive charge mass C (energy supplier) and a casing mass M are known in the art. The Gurney equation μ=M/C determines the velocity v, and therefore the impulse I=Mv or the kinetic energy E kin =M/2v 2  of the casing. 
     The residual energy of the total explosive energy E tot  stored goes into the blast power E B  of the explosive charge. These two components together, splinter energy and blast energy (E kin +E B ), therefore determine the total power of a blast/splinter charge. 
     There is an optimum for the kinetic energy or else the impulse of a charge. The optimum depends on predefined marginal conditions; in this case, for example, a constant total mass and constant caliber. Alternatively, for example, a constant total volume could also be required. 
     The achievement of an optimum requires a given ratio of M and C to one another. This optimum is frequently sought if no other marginal conditions are specified, such as a thick charge casing for a penetrator to perforate structural targets with thick concrete walls, for example. There are therefore frequently constraints when it comes to deciding which M-to-C ratios can be chosen. 
     The maximum blast power that can possibly be attained requires the oxygen in the air to be used for the after-reaction, in other words for the combustion of the total explosive vapors produced to be utilized. This is because military explosives are heavily oxygen-underbalanced, i.e. the total possible blast power is only partially released during detonation. There are still a large number of incompletely oxidized molecules in the vapor, such as C, CO, HO (or extra added metal powder such as Al) rather than CO 2  and H 2 O (or Al 2 O 3 ), for example. Complete oxidation of these vapors requires adequate blending with the ambient air, however. 
     Tests have revealed that these after-reactions with air can be entirely suppressed, i.e. there is only negligible after-combustion, leading to a correspondingly sharp reduction in blast power. It was possible to demonstrate in this case that the difference between the complete blast power and suppressed blast power is, for example, up to 400%. 
     The explanation for this phenomenon lies in the sharp temperature drop caused by adiabatic expansion of the vapor gases. Before the casing rips open and the explosive vapors are mixed with air and react with the oxygen, the vapors have cooled down to such an extent that they have fallen below the thresholds of the reaction temperatures for different gas molecules (e.g. CO)—there is a complete suppression of vapor reactions. 
     The problem addressed by the disclosure herein is therefore that of specifying a method with which a known warhead can easily be switched between splinter generation and pressure (blast) generation. 
     As has already been stated, the casing acts as a barrier between the expanding vapors and the ambient air. Any delay in removing this barrier results in the vapor temperatures having already fallen below the reaction thresholds, so that the reactions are suppressed. 
     SUMMARY 
     The problem is solved by the prompt removal of this barrier. There are two possible ways of doing this which can support and complement one another through coordination and harmonization. 
     According to the disclosure herein, the solution comprises a method with the following steps that can be selectively implemented:
         following the triggering of only the first ignition device and then ensuing deflection of the detonation front produced, which extends in a substantially glancing manner between the casing and the perforated mask made of a porous RSM (Reactive Structure Material), the detonation front is additionally damped by the perforated mask, as a result of which no chemical reaction takes place in the porous RSM and as a result of which the splinters of the casing are radially accelerated without a significant blast reaction taking place,   following the triggering of only the second ignition device, the detonation front produced strikes the perforated mask made of a porous RSM substantially perpendicularly, as a result of which the explosive particles passing through the holes of the perforated mask fragment the casing and then the perforated mask too, and as a result of this a complete after-reaction of the explosive vapors then follows due to the oxygen which is then available,   when the first and second ignition devices are triggered at selectable points in time, there is a distribution of splinter generation or blast generation that depends on the ignition timing.       

     Further advantageous embodiments can be inferred from the dependent claims. 
     A particular advantage of the solution according to the disclosure herein is that for the first time the optional use of different initiation sites in one case leads to the complete suppression of after-reactions and therefore to the selective elimination of the blast effect. In the other case, there is a complete after-reaction of the oxygen-underbalanced vapors and therefore an extremely high blast effect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the disclosure herein are depicted in the drawing and are described in greater detail below. In the drawing: 
         FIG. 1 : shows a cylindrical warhead with an integrated perforated mask, 
         FIG. 2 : shows different warhead initiation modes. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a warhead GK with two different ignition points ZK 1 , ZK 2  which can be initiated either individually but also jointly at selectable times. The one ignition device ZK 1  is arranged on the head side K of the warhead GK in the region of a detonation wave deflector DW. The second ignition device ZK 2  is mounted roughly centrally in the explosive charge SP on the longitudinal axis L of the warhead. 
     The centrally arranged explosive charge SP is surrounded by a perforated mask LM on the outside. This bears directly against the casing H of the warhead GK. 
     Depending on which ignition device is selected, a situation such as that depicted on the left or right in  FIG. 2  results during the initiation of the ignition device according to the method described here. For this purpose, in respect of the known methods, those in extended form will be used. 
     On the one hand, the materials of the casing H and the strengths thereof are selected in such a manner that a strong, quick fragmentation and therefore early opening to allow the vapors to escape is guaranteed. This may be achieved through special sintering of metal particles, for example. High-density materials such as molybdenum or tungsten alloys are available for this. 
     On the other hand, this is supported by switchable methods of opening the casing. The functionality and switchability of the methods are depicted in  FIG. 2 . In the left partial image, the detonation fronts depicted using dotted lines strike the perforated mask LM perpendicularly at the front. This means that particle jets are produced very quickly, the particle jets exposing the casing to extreme loads and fragmenting it. On the right side of  FIG. 2 , a switch has been made to glancing mode. In this case, no more particle jets are produced and there is no early fragmentation of the casing. Consequently, the suppression of after-reactions also brings about the selective elimination of the blast effect. 
     In the left partial image in  FIG. 2 , the locally limited blast mode is depicted which avoids collateral damage. In this case, the casing fragmentation mode is activated. The casing is quickly and effectively fragmented and subfragmented into small and minutely small splinters which do not fly far, as they are quickly braked by the air. The vapors can escape quickly and mix with the surrounding air. There is a complete after-reaction of the oxygen-underbalanced vapors. An extremely high blast effect is therefore produced locally, due to the ultra-finely fragmented, rapid metal particles of the casing in addition to the blast from the 100% vapor reactions. Effects with a wider coverage (a few 100 m) are not desirable and neither are they to be expected. 
     The right partial image in  FIG. 2  shows the known method of exclusive splinter formation. The method of fragmenting the casing is precluded in this case. This means that no particle jets are produced. Detonation takes place as usual, so that the splinters (whether natural or preformed splinters) are not fragmented or subfragmented, but they are accelerated as customary and fly over large distances (a few hundred meters) and are able to be fully and effectively deployed in the military target. There is a cessation of after-reactions and a very sharply reduced blast effect. This is in any case confined to a limited area and is not required here to support the power output. 
     It is of course also possible by a roughly simultaneous initiation of both ignition devices ZK 1  and ZK 2  for a mixed form of the two aforementioned effects to be achieved. 
     While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.