Muzzle attachment for accelerating a projectle
United States Patent i 1 Korr et al.  
 l Apr. 29, 1975 MUZZLE ATTACHMENT FOR ACCELERATING A PROJECTLE [75] Inventors: Abraham L. Korr. Philadelphia. Pa.;  
 Evan Harris Walker. Aberdeen. Md.  
 [73] Assignee: The United States of America as represented by the Secretary of the Army. Washington. DC.  
 [22] Filed: July 5. I973 [2i] Appl. No.: 376,655  
 [52] US. Cl. 89/8: 42/! F [5|] Int. Cl F-llf H00 [58] Field of Search 89/l. 8142/1 F; 102/652 [56] References Cited UNITED STATES PATENTS l,463.993 8/l973 Burt 41/] F 2.094.305 9/1937 Savani 42 F 3.031.933 5/]962 Kern et al. 89/8 3.054.329 9/1962 Willig A. 89/8 3357306 l2/l9b7 Boyd et al .0 89/8 3.388.666 6/ I968 Walther 3.479.956 I l/ I969 Birkigt 3.503.300 3/[970 Dardick 89/8 Primary Eruminer-Stephen C. Bentley Aunrm&#39;y. Agent. or Firm-William Sommer; Nathan Edelberg; Robert P. Gibson 57] ABSTRACT An efficient hypervelocity weapon system is described in which a conically-hased projectile is initially launched from a reusable conventional gun into an aligned cylindrical tube of high explosive which is initiated by the rotating band located at the juncture of the conical base and the rearward end of the hourrelet. As the projectile moves through the high explosive tube. the gases generated from its detonation implode upon the conical projectile base rearwardly of the rotating band and cause the projectile to accelerate to a hypervelocity range in the direction of travel.  
 6 Claims, 1 Drawing Figure MUZZLE ATTACHMENT FORACCELERATING A PROJECTLE The invention described herein may be manufactured. used. and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.  
  This invention relates to weapon systems. and more particularly to a weapon system in which a projectile. fired from a conventional gun. is accelerated to a hy pervelocity range.  
  Most hypervelocity projectile accelerators achieve acceleration by applying within the weapon a high pressure gas behind the projectile. The maximum velocity that can be achieved in this manner is limited to approximately l km./sec. where the integrity of the projectile is not destroyed unless high gas pressures are developed that exceed the crushing strength of the projectile.  
  One of the objects of the invention is to provide a reusable weapon system in which a projectile can be fired at a final launch velocity several times as great as the foregoing limited maximum velocity. while maintaining its integrity.  
  Another object of the invention is to provide such a weapon system in which the projectile is propelled to a velocity greater than the velocity of the propelling gas.  
  Another object of the invention is to provide such a system which more efficiently utilizes explosive materials as projectile accelerators.  
  A further object of the invention is to provide such a system in which a projectile is launched from a lightweight conventional weapon and delivered to a target with a minimum time of flight.  
  These and other objects. features and advantages will become more apparent from the following description and accompanying drawing which is a longitudinal sectional view during launching ofa projectile in a weapon system embodying the principles of the invention.  
  The weapon system, shown generally at 10, includes a conventional rifle barrel 11 having internal rifling grooves 12 through which the deformed rotating band portions 13 on projectile 15 have travelled prior to their launched departure from the barrel open muzzle end 14. The external surface of barrel open end 14 has a threaded portion 16, upon which a transparent shield 17 and its internally threaded collar 18 is secured by lock nut 19, a forwardmost cylindrical portion 21 of somewhat smaller diameter than the threaded portion 16 so as not to interfere with mounting of the shield. and an intermediate annular conically tapered portion 22. The shield 17 is affixed to the collar 18 by a pair of diametrically opposed locking pins 20, 20 each having suitable end nuts. The shield 17 has a suitable front sight 17A etched on the rearward surface of the transparent body.  
  The disposable adapter 32 has a pair of longitudinally spaced tubular portions 30, 31 and an intermediate tubular portion 34 which is connected to the concentric and relatively smaller tubular portions 30, 31 by corresponding laterally extending annular end members 35, 36. The adapter intermediate cylindrical portion 34 has a plurality of longitudinally and transversely extending ribs that define openings 37 in its sidewall. The rearmost end of the adapter is provided with a pair of diametrically opposed handle portions 38, 39 that also connect the adapter sidewall 34 with the rcarmost end of the first or rearward tubular portion 30. The rearmost internal surface of tubular portion 30 is recessed or relieved at 25 to accommodate threads 16 on assembly. The annular recess 25. upon assembly. has its base portion defined by the swaged mating of tubular portion 30 upon barrel conical portion 22.  
  Press-fitted in the adapter forwardmost tubular portion 3i is an explosive tube 40 which is formed by molding an explosive cylinder 41 within a combustible plastic tube 42. The explosive tube 40 is of predetermined dimensions. perhaps the most significant of which is that the inside diameter of the explosive cylinder 4] is slightly less (approximately 0.001 inch) than the muzzle bore. such that the forward edges of the rotating band portions 13 will upon contact initiate the explosive cylinder. The pressfitted connection between the explosive tube 40 and the adapter tubular portion 31 is sufficiently tight enough to withstand the impact of the rotating band portions 13 on the explosive tube, although the press-fit connection could be provided with ridges or other deformations to assure a sufficiently secure operative connection. The adapter 32 serves to mount the explosive tube in a position longitudinally spaced from and in longitudinal operative alignment with the barrel muzzle end 14. Preferably. the explosive cylinder 41 is a low detonation velocity explosive selected from the group consisting of Hivelite. low density ammonium perchorate. and PETN (pentaerythritol tetranitrate) interspersed with metallic or other non-combustible disc interruptors.  
  The projectile 15 has a tail portion 45 having a substantially conically shaped lateral surface 46 that is continuously tapered from its forwardmost portion adjacent the rotating band means 13 to the terminal apex. The preferred angle of taper is 6 although the acceptable range is between 2 and 30.  
  As the projectile rotating band portions 13 ignite the explosive cylinder 41, the implosion of the detonated or generated gases apply a resultant force vector upon the conical surface 46 of the projectile tail 45 in the direction of projectile travel through the explosive tube. to thereby accelerate the conventionally launched projectile to a hypervelocity range.  
  Various modifications. changes or alterations may be resorted to without departure from the scope of the invention as defined by the appended claims.  
 We claim:  
  1. In a weapon arrangement having a barrel with an open muzzle end.  
 a disposable substantially cylindrical adapter having openings defined by ribs in its sidewall and secured to an external surface of said barrel open end, and  
 means including an explosive tube for accelerating a projectile launched conventionally from said barrel to a hypervelocity range. said explosive tube including a combustible plastic tube secured to a forward portion of said adapter and extending forwardly of said adapter, said plastic tube surrounding and containing a molded explosive cylinder. said molded explosive cylinder being in longitudinal alignment with and longitudinally spaced forwardly ofsaid barrel, said explosive cylinder having an inside diameter slightly less than the bore of said barrel muzzle end.  
 2. The structure in accordance with claim 1 wherein said adapter has a first tubular portion secured to said barrel. a second tubular portion secured to said explosive tube, said second tubular portion being longitudinally spaced from said first tubular portion. and an intermediate tubular portion integral with both said first and second tubular portions. said intermediate tubular portion having a plurality of openings in its sidewall.  
  3. The structure of claim 2 wherein said intermediate tuhular portion is concentric with and radially spaced outside of both said first and second tubular portions. and a pair of diametrically opposed handles are respectively integral with both said first and intermediate tubular portions.  
  4. The structure of claim I wherein a shield is secured to said external surface of said barrel rearwardly of said adapter.  
  5. The structure of claim 4 wherein said adapter has a first tubular portion secured to said barrel. :1 second tubular portion secured to said explosive tube. said second tubular portion being longitudinally spaced from said first tubular portion. and an intermediate tubular portion integral with both said first and second tubular portions. said intermediate tubular portion having sidewall. plurality of openings in its sidewalls.  
  6. The structure of claim 5 wherein said intermediate tubular portion is concentric with and radially spaced outside of both said first and second tubular portions. and a pair of diametrically opposed handles are respectively integral with both said first and intermediate tubular portions.