Abstract:
A multi-part projectile accelerator to be used in the single or multiple projectile mode, constructed of the hollow and tubular body which may either self-disconnect, once the projectile leaves the barrel, or stay with the projectile for the duration of the flight; which may also include the ring member designed to fit into the grooves of the rifled barrel in order to assist in maintaining the rotation of an accelerator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Current patent application is a National stage application from PCT application No. PCT/IL2014/050539 filed on Jun. 15, 2014 which claims priority to Israeli patent application IL229290 filed on Nov. 7, 2013. 
     TECHNICAL FIELD 
     The present invention pertains to area of armament, including barreled weapons, rifled weapons, smooth-bore weapons, artillery systems and ammunition. 
     DESCRIPTION OF THE RELATED ART 
     From analyzing the development of barreled firearms and artillery it is evident that the development of metallurgy, chemistry, optics and electronics allows to create a reliable, rapid-firing and highly-precise weapon systems and ammunition. Guided and smart munition, and projectiles are known in the art as well. Despite the ongoing technical progress in weapon design, there is no improvement that would be responsible for the increase of muzzle energy of a projectile. 
     Russian patent RU2372581 describes a cartridge with as jet-bullet. In this patent, the bullet has a complicated structure and due to its thin walled cavity it is unable to withstand high pressure needed to achieve high velocity. 
     Russian patent RU2151371 describes a bullet with as cavity. The bullet is supposed to be further accelerated by the escaping gases from its cavity. 
     Russian patent RU2150074 describes a bullet with a propellant charge. However due to the low power of the propellant charge, the gain of speed is minimal. 
     Other relevant armaments are M198 duplex cartridge and multiple projectile cartridge described in Russian patent RU2438093. 
     Other relevant publications are: Patents: RU2107886, RU2372251, RU2206052, RU2151371, RU2453801, RU2287769, RU2099667, RU2150074, RU2075033, RU2100769, RU2438093; and books: I. Strezhnev. Artillery pieces with segmented kinetics (1944-48), Serebryakov M. Internal ballistics of barreled systems and solid fuel rockets. Moscow Oborongiz 1962; Gorokhov M. Internal ballistics of barreled systems. Moscow 1985; Kirillov V., Sabelnikov V. Firearm ammunition. Moscow 1980. Malov A. Manufacture of firearm ammunition. Moscow Oborongiz 1947; Menshikov N. Album of designs of large caliber firearms for automatic weapons. Moscow 1947; Murahovskiy V., Fedoseev S. infantry weapons. Moscow, Arsenal-Press 1992; Safaryants A. Cartridge and casing production technology. Training manual for colleges 1975; Basics of the device and the design of guns and ammunition of land based artillery. Moscow Military Publishing House of the USSR Ministry of Defense 1976. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the invention, a projectile accelerator is provided. The accelerator comprises a tubular body with one sealed end and a nozzle at the opposite end thereof. The accelerator is attached by the sealed end (either permanently or non-permanently) to a projectile. 
     The accelerator may have a form of a hollow bullet and may be utilized in a single or a multiple projectile cartridge. 
     In accordance with another aspect of the invention, a method for creating a barreled weapon is disclosed. The weapon has a barrel length that increases or maximizes the energy stored in the accelerator, 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a side cut-off view of an embodiment of an accelerator inside a cartridge; 
         FIG. 2  is a side cut-off view of an embodiment of a detachable accelerator inside a cartridge; 
         FIG. 3  is a side cut-off view of another embodiment of a detachable accelerator inside a cartridge; 
         FIG. 4  is a side cut-off view of an embodiment of a bullet shaped accelerator inside a cartridge; 
         FIG. 5  is a side cut-off view of an embodiment of a bullet shaped accelerator inside a multiple projectile cartridge; 
         FIG. 6  is a side cut-off view of an embodiment of a bullet shaped accelerator having a jacketed lead head; and 
         FIG. 7  is a graph showing curves of pressure, velocity and time of the bullet motion in a rifle bore. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention comprises an improvement in projectile design and is intended to increase the muzzle energy of a projectile. The increase in muzzle energy of a projectile is achieved by including an additional component, an accelerator, in the projectile structure. Usually, a projectile (for example, a bullet) is projected in two steps. In the first step, the projectile is accelerated, in the barrel, and in the second step, the projectile continues with its motion due to the inertia. Due to the accelerator, an additional step may be included in the projection process. This step provides an additional acceleration, caused by the accelerator. The additional acceleration begins immediately once the projectile leaves the barrel. The accelerator allows to significantly increase, by order of magnitude, a muzzle velocity and the muzzle energy of the projectile. 
     Due to the high temperature (up to 2500° C.), that affects the accelerator during the acceleration, and high pressure (more than 350 MPa), that affects the accelerator during the additional acceleration, it is advisable to manufacture said accelerator from a heat resistant, light and strong material such as a high strength steel. 
     In one embodiment, as depicted in  FIG. 1 , an accelerator  104  is designed to have a tubular form with an outer diameter smaller by 1% to 5% than a projectile caliber (C). The accelerator  104  has a sealed end no and a nozzle  111  located at the opposite end thereof. The accelerator  104  is located inside a case  102 , and there is a gap between the nozzle  111  and a case base  112  ranging from a half to a full caliber length. The accelerator  104  is coaxially connected, by its sealed end  110 , to a bottom surface  105  of the projectile  101 , wherein said connection is either a permanent connection or a non-permanent connection. 
     In a case of a non-permanent or detachable connection of an accelerator to a projectile, the accelerator is removed from the projectile by an incoming stream of air, after the projectile leaves a barrel. 
     In another embodiment, as depicted on  FIG. 2  and  FIG. 2A , an accelerator  204  is detachably connected, by a pin  207 , to a hole  213  in a projectile  201 . The hole  213  is located on the bottom surface of the projectile  201 . A nozzle  211  of the accelerator  204  contains a ring member  214  with legs  206  that help in maintaining an axial position of the nozzle  211 . The legs  206  are adapted to fit inside the grooves  54  of a rifle barrel  208  and thus assist in maintaining the rotation of the accelerator  204  and the projectile  201  during their movement thought the barrel  208 . The legs have (1) a separation (i.e. space)  50 , between each leg  206 , (2) a thickness  51 , and (3) a width  53 . The grooves  54  have (1) a groove length  52  and (2) a groove width  55 . 
     In yet another embodiment, as depicted in  FIG. 3 , an accelerator  304  is detachably connected by a concentric ring  308  to a tapered end of a projectile  301 . 
     In yet another embodiment, as depicted in  FIG. 4 , an accelerator  404  has a form of a hollow bullet and it can be used with single projectile ammunition. 
     In yet another embodiment, as depicted in  FIG. 5 , an accelerator  504  has a form of a hollow bullet and it can be used with multiple projectile ammunition. 
     In yet another embodiment, as depicted in  FIG. 6 , an accelerator  604  includes a jacketed lead head  609 . 
     Due to the additional thrust, caused by the accelerator, the projectile gains an additional speed. This gain in speed is a function of the pressure inside the accelerator and its operation time. The operation time of an accelerator is a function of its volume and the gas speed at the nozzle. The accelerator&#39;s volume is devised from the inner dimensions of the cartridge. The gas speed at the nozzle depends on physical characteristics and temperature of the propellant gas. 
     The pressure inside the barrel (and thus the pressure inside the accelerator) could be controlled by utilizing high pressure gases present in the barrel, as shown in the pressure vs. barrel length graph depicted in  FIG. 7 . As shown in the graph, the pressure in the barrel increases with a decrease in length of the barrel. 
     Decreasing the length of the barrel causes an increase in the gas energy stored in the accelerator, and thus a higher speed and energy during the additional acceleration phase. 
     For example, if the barrel of a Mosin rifle is shortened to 100 mm, the pressure at that point may be 250 MPa and the bullet speed may be increased by factor of two or three and the muzzle energy may be increased anywhere from 400% to 900%. 
     An increase in muzzle energy would cause an increase in a: velocity of a projectile, stopping power of a projectile, a penetration depth, an effective range, fire power (for multiple projectile ammunition), projectile weight. 
     A decrease in band length would reduce the weight of a weapon, its size, the cost of production and make the manufacturing process less complicated. 
     There are several options for using accelerator based ammunition: 
     Using an accelerator with current and unmodified weaponry. In this case the muzzle energy might be increased by 13% to 94%. 
     Using an accelerator with a modified weaponry. The weapon is modified by:
     a. shortening the barrel (and thus increasing the barrel pressure according to a pressure vs. barrel length graph), the muzzle energy could be increased, by 305% to 783%;   b. boring the barrel till the desired barrel pressure is reached (according to a pressure vs. barrel length graph). The boring also increases the barrel caliber by 5% to 15%. The muzzle energy in this case could be increased by 305% to 783% as well.   

     Another option is to design a new barrel, adapted for firing an accelerator based ammunition. 
     The greatest increase in muzzle energy could be achieved when the weaponry and the ammunition are specifically designed for use with an accelerator.