Layered projectile for close-in weapon system
0 United States Patent 11 1 1111 3,877,380 Riparbelli Apr. 15, 1975 LAYERED PROJECTILE FOR CLOSE-IN 1,432,669 10/1922 Clay 102/52 WEAPON SYSTEM 2,682,224 6/1954 Braverman 102/91 3,255,698 6/1966 Lindberg, Jr.. 102/105 Inventor: Carlo p lli, a, Cal 3,370,535 2/1968 Permutter 102 91 x [73] Assignee: The United States of America as 3,599,573 8/1971 Shney 102/92.4  
  represented by the Secretary of the Navy, Wa hingto DC, Primary ExaminerRobert F. Stahl Attorney, Agent, or Firm-R. S. Sciascia; P. Schneider; [22] Filed: July 21, 1972 Sturm [21] Appl. No.: 277,212  
  [57] ABSTRACT 52 U.S. Cl 102 2. 102 Int CL 1;: A projectlle havmg layers of metal separated by layers [58] Fieid 92 4 92 2 of another material which may also be metal, the configuration of the layers being generally conical or frustoconical, thereby inhibiting the formation and propa- [56] References Cited gation of impact cracks which often form in a projectile subjected to a high impact, to thereby maintain UNITED STATES PATENTS the projectile in one piece. 1,333,834 3/1920 Clay 102/52 1,380,773 6/1921 Clay 102/52 5 Claims, 2 Drawing Figures LAYERED PROJECTILE FOR CLOSE-IN WEAPON SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to projectiles and more particularly to projectiles subjected to a high velocity impact or repeated impacts, such as when projectiles must perforate multiple shells or plates, wherein there is a need for the projectile to retain structural integrity such as to remain in one piece.  
 2. Description of the Prior Art The most common type of projectile is made ofa single material and has a disadvantage in that once a crack or breakdevelops in the projectile while in flight, there is nothing to prevent the crack from causing a complete separation of parts of the projectile. This is true, at least to some extent, even in the composite projectiles of the prior art.  
 SUMMARY OF THE INVENTION The present invention of conical and frusto-conical layers of annealed copper between layers of depleted uranium prevents cracks from separating parts of the projectile and reduces the machining necessary for projectiles made of very hard materials.  
 OBJECTS OF THE INVENTION An object of the present invention is to provide a projectile structure which will maintain one-piece integrity impact.  
  Another object is to reduce the machining necessary for a projectile.  
  Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawmgs.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a longitudinal cross section of the preferred embodiment of the invention.  
  FIG. 2 shows a longitudinal cross section of another embodiment of the present invention.  
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a projectile 1 comprising a solid memher, or body, 8 which may, for example, be pointed layer 2, and frusto-conical layers 4, 6, and 8 constructed of depleted uranium or other suitable material. The shape of the body is usually cylindrical with a ta-- pered or conical nose section 9 at the front (at the left in FIGS. 1 and 2). Alternating layers of soft material, such as copper, and of the material of the main body are affixed to the nose section. Thus, in FIG. 1, layers 7, 5 and 3 are of copper and layers 6, 4 and 2 are of deand 17 of copper or other relatively soft materials. Layer 17 is conical in shape and layers 15 and 13 are respectively less pointed and more rounded toward the front of the projectile.  
  In a close-in weapon system such as the Phalanx, high velocity and high density projectiles penetrate the structure of the incoming enemy missile and its warhead causing its destruction. The structure of the warhead consists of a sequence of plates or sheels which the projectile must cross. In order to cause detonation or deflagration of the warhead explosive, it is essential that the whole projectile or a large fragment of it impacts the explosive.  
  Tests have shown that projectiles easily break following impact with the plates, and an analysis of the tests shows very high stresses and pressure in the projectile near the point of impact at the nose. With the projectile material and velocity considered, the stresses, both compressive and tensile are measured millions of pounds per square inch, which the material normally cannot stand without breaking.  
  The present invention is a projectile composed of layers of a chosen metal bound together either by forcing and friction or by means of intermediate layers of a soft material which may be metallic or nonmetallic. The main purpose of the layer structure is to break the path of the cracks irradiating from highly stressed regions. The projectile nearthe point of impact will indeed break. The purpose of&#39;the layer structure is to limit the loss of mass by limiting the length of the cracks.  
  If the projectile is built of depleted uranium, thin layers of annealed copper such as layers 3, 5, and 7 of FIG. 1 or layers 13, 15, and 17 of FIG. 2, may be inserted between the layers of depleted uranium, and the package may be pressed together. Advantages of this construction include reflection-damping of the strain waves at the transition between the different materials, and the economy of construction because the copper layers make the precise machining of the depleted uranium layers unnecessary.  
  In FIG. 2, the body 18 of the projectile is sharply tapered so that it has a very small cylindrical portion 19. However, the layers on the nose are extended backwards to build up the body portion sufficiently to form an aerodynamic shape which, in most cases, will be substantially a bullet-shape; i.e., a long cylindrical portion with a tapered nose.  
  The invention is not limited to the use of conical or frusto-conical layers, for example paraboloid and other tapered-surface shapes may utilize the present invention to provide a projectile which, like the conical embodiment, tends to retain one piece integrity but which is effective even if one or more of the layers are separated from the main projectile.  
  Obviously many modifications and variations of the present invention are possible in 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:  
 1. A projectile comprising:  
 a solid main body having a cylindrical section and a tapered nose section;  
 at least one conically shaped layer of another material affixed to and conforming to the shape of said tapered nose section, said other material being soft in comparison to the material from which said main body is fabricated; and  
 at least one conically shaped layer, formed from the same material from which said main body is fabricated, affixed to and conforming to the shape of 5 layer upon target impact. 2. A projectile as in claim 1, wherein there are more than one set of said conically shaped nose layers.  
 3. A projectile as in claim 1, wherein said soft layer is formed from copper and said main body and said outer layer are formed from depleted uranium.  
 4. A projectile as in claim 1, said nose section having a sharp point.  
 5. A projectile as in claim 1, said nose section having a rounded point.