Abstract:
A kinetic energy enhancing penetrator assembly for use with an archery arrow comprises a weighted arrow insert and a resilient member. The weighted arrow insert includes a semi-cylindrical body and a base extending from the body for releasable engagement with a nock of the arrow. The weighted arrow insert additionally includes a tapered head for engagement with the resilient member. The weighted arrow insert includes a feature enabling passage of air thereby reducing compression of air entrapped within a bore of an arrow shaft and any resulting resistance. The resilient member includes a coil spring affixed to a rear end of the insert for buffering impact of the weighted arrow insert against an arrowhead of the arrow. In use, the penetrator assembly within an arrow applies a secondary burst of kinetic energy upon the arrowhead upon impact with a target.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a kinetic energy enhanced arrow and method of enhancing the kinetic energy imparted by an archer&#39;s arrow or bolt to tissue, and more particularly, a kinetic energy enhanced arrow having a weighted insert movably mounted within the arrow and releasable upon engagement with tissue to impart additional kinetic energy to the arrowhead of the arrow. 
     BACKGROUND OF THE INVENTION 
     During hunting with archery equipment, it is desirable to have the arrow pass completely through the animal to ensure a clean kill and increase the possibility of a larger blood trail. Often, older manufactured bows lack the power to impart sufficient energy to the arrow, either through design or age, resulting in insufficient penetration of tissue to ensure a complete pass through. This is especially true if the arrow impacts bone structure such as ribs or shoulder bone. 
     Many archers must use light-weight bows due to shoulder injuries. Additionally, youth or weaker archers use lighter weight bows, as they do not have the strength to pull back heavy weight bows. 
     Some modern bows utilize cams to increase the energy imparted to the arrow while keeping the pull or draw weight reasonable for injured or weak archers. Alternatively, light weight arrows, such as carbon arrows, are available and allow for increased arrow speed from light weight bows to provide increased energy upon impact with tissue. 
     However, modern cam assisted bows, carbon arrows and other high tech equipment is often very expensive and out of reach of many archers. 
     Accordingly, there exists a need in the art for an apparatus and method of increasing the kinetic energy of an arrow upon impact with tissue. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the deficiencies of the known art and the problems that remain unsolved by providing a method and apparatus for enhancing the kinetic energy imparted by an archery arrow or bolt to tissue. 
     In accordance with one embodiment of the present invention, the invention consists of a penetrator assembly for use with an archery arrow or bolt having a tubular shaft comprising: 
     a weighted arrow insert having a body portion and a base extending rearwardly from the body portion, wherein a diameter of the body portion is substantially equal to an interior diameter of an arrow shaft through bore extending through the tubular shaft; and 
     a resilient member. 
     In a second aspect of the invention, the body portion further comprises a feature enabling passage of air from a front end of the weighted arrow insert past a rear end of the weighted arrow insert to reduce any compression of air entrapped within the arrow shaft through bore. 
     In another aspect of the invention, the body portion is semi-cylindrical and includes at least one flat side. 
     In another aspect of the invention, the body portion has first and second arcuate sides and first and second flat sides. 
     In yet another aspect of the invention, the weighted arrow insert has a tapered head extending forwardly from the body portion. 
     In yet another aspect of the invention, the tapered head has a conical shape. 
     In yet another aspect of the invention, the tapered head has a flat impacting tip. 
     In yet another aspect of the invention, the tapered head has at least one flat side. 
     In yet another aspect of the invention, the resilient member is a spring. 
     In yet another aspect of the invention, the spring is a coil spring. 
     Introducing another embodiment of the present invention, the invention consists of a kinetic energy enhanced arrow comprising: 
     a tubular shaft having a through bore extending between a front shaft end and a rear shaft end; 
     an arrowhead affixed to the tubular shaft front end; 
     a nock affixed to the tubular shaft rear end; and 
     a weighted arrow insert slideably assembled within the through bore and releasably attached to the nock. 
     In another aspect of the invention, the nock defines a bore and the weighted arrow insert includes a base releasably positioned in the bore of the nock. 
     In yet another aspect of the invention, the weighted arrow insert has a semi-cylindrical body. 
     In yet another aspect of the invention, the weighted arrow insert has a tapered head. 
     In yet another aspect of the invention, the invention further comprises a resilient member positioned within the through bore forward of the weighted arrow insert. 
     In yet another aspect of the invention, the invention further comprises an insert positioned within the front end of the tubular shaft and affixed to the arrowhead. 
     In yet another aspect of the invention, the resilient member is affixed to the insert. 
     In yet another aspect of the invention, the resilient member is a coil spring. 
     Introducing another embodiment of the invention, a method of imparting kinetic energy to an arrow comprising steps of: 
     obtaining an arrow, comprising:
         a tubular shaft having a through bore extending between a front shaft end and a rear shaft end,   an arrowhead affixed to the tubular shaft front end, and   a nock affixed to the tubular shaft rear end;       

     providing a weighted arrow insert having a body and a base extending rearwardly from the body; 
     releasably engaging the base of the weighted arrow insert with the nock; 
     inserting the weighted arrow insert within the through bore at a location between the nock and the arrowhead; 
     releasing the weighted arrow insert from the nock by advancing the weighted arrow insert from the nock; 
     propelling the weighted arrow insert through the tubular shaft; and 
     impacting an element located proximate the front end of the tubular shaft with the weighted arrow insert. 
     In another aspect, the method further comprises providing a resilient member positioned within the tubular shaft and impacting the resilient member with the weighted arrow insert. 
     In yet another aspect, the method further comprises compressing the resilient member with the weighted arrow insert to further impact the front end of the tubular shaft. 
     These and other features, aspects, and advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The presented embodiments of the invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not limit the invention, in which: 
         FIG. 1  presents an isometric view of an exemplary weighted arrow insert; 
         FIG. 2  presents an isometric view of an exemplary kinetic energy enhanced arrow; 
         FIG. 3  presents an enlarged exploded isometric view of a rear section of the exemplary arrow originally introduced in  FIG. 2 , showing an enlarged exploded view of an arrow fletching and nock and illustrating placement of the weighted arrow insert through a rear section of the arrow shaft; 
         FIG. 4  presents and enlarged exploded isometric view of a front section of the exemplary arrow originally introduced in  FIG. 2 , showing an enlarged exploded view of an arrowhead, an arrowhead insert, and a front section of the shaft; 
         FIG. 5  presents a longitudinally sectioned view of the exemplary arrow originally illustrated in  FIG. 2 , illustrating placement of the weighted arrow insert within the arrow; 
         FIG. 6  presents a longitudinally sectioned view of the front section of the exemplary arrow originally introduced in  FIG. 2 , illustrating the arrow contacting a target and showing the weighted arrow insert traveling forward within the shaft towards the arrowhead; 
         FIG. 7  presents a cross longitudinally sectioned view of the front section of the exemplary arrow originally introduced in  FIG. 2 , illustrating the arrow being further driven into the target and showing the weighted arrow insert striking a spring, delivering a first burst of kinetic energy; 
         FIG. 8  presents a longitudinally sectioned view of the front section of the exemplary arrow originally introduced in  FIG. 2 , illustrating the weighted arrow insert compressing the spring, delivering a second burst of kinetic energy, driving the arrowhead even farther into the target; and 
         FIG. 9  presents a schematic illustration presenting exemplary distinct distances traveled by the launched arrow, originally introduced in  FIG. 2 , as the launched arrow contacts and penetrates the target, while receiving the two additional bursts of kinetic energy provided by the weighted arrow insert. 
     
    
    
     Like reference numerals refer to like parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments of the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure, which is defined by the claims. For purposes of description herein, the terms “upper”, “lower”, “left”, “rear”, “right”, “front”, vertical”, “horizontal”, and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relative to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     A weighted arrow insert  100  is presented in  FIGS. 1 ,  3  and  5 - 8  for use in a kinetic energy enhanced arrow  150  ( FIG. 2 ). Referring initially to  FIG. 1 , the weighted arrow insert  100  generally includes a semi-cylindrical collar  110 , a tapered head  112  and a base  114  extending rearwardly from collar  110 . The tapered head  112  terminates at a flat tip  116 . The flat tip  116  can be described as being planar. The plane defined by the flat tip  116  is preferably perpendicular to a longitudinal axis of the weighted arrow insert  100 . The collar  110  includes a front end  118 , a rear end  120 , a first arcuate outer surface  122  and a second arcuate outer surface  124 . An outside diameter of the collar  110  between the arcuate outer surfaces  122 ,  124  is substantially equal to an interior diameter of a through bore  202  (see  FIG. 5 ) of an arrow shaft  152 . A first flat outer surface  126  and a second flat outer surface  128  are formed between the first and second arcuate outer surfaces  122  and  124  such that the diameter of the collar  110  between the flat outer surfaces  126 ,  128  is less than the outside diameter of the collar  110  between the arcuate outer surfaces  122 ,  124  so as to provide a feature on the collar  110  enabling passage of air flow along the feature and around and past the collar  110  and from a front end and past a rear end of the weighted arrow insert  100  as the weighted arrow insert  100  travels through the arrow  150  in a manner described in more detail herein below. It will be readily understood that this feature will reduce any compression of air entrapped within the arrow shaft through bore caused by the travel of the weighted arrow insert  100  therein. 
     The tapered head  112  has a rear end  130  and a front end  132 . The rear end  130  of the tapered head  112  extends from the front end  118  of the collar  110  while the front end  132  of the tapered head  112  terminates at the flat tip  116 . The tapered head  112  has a conical outer surface  134  having a first flat portion  136  and a second flat portion  138  formed at the rear end  130 . The first and second flat portions  136  and  138  formed on the tapered head  112  are preferably in longitudinal alignment with the first and second flat outer surfaces  126  and  128  formed on the collar  110  and assist in the flow of air on and over the weighted arrow insert  100 . 
     The base  114  is cylindrical in shape, extending between a front end  140  and a rear end  142 . The front end  140  extends from the rear end  120  of the collar  110  and the rear end  142  of the base  114  terminates at a flat rear face  146 . As shown, diameter D1 of the base  114  is less than the diameter D2 of the collar  110 . This results in a rear face  148  on the rear end  120  of the collar  110 , which allows the weighted arrow insert  100  to seat within the arrow  150  in a manner described in more detail herein below. The diameter D2 of the collar  110  is generally proximate a diameter of an interior of the arrow shaft through bore  202  ( FIG. 6 ) of the arrow tubular shaft  152 . 
     The weighted arrow insert  100  may be formed from a variety of materials, such as, for example, ceramics, polymers or metallic materials. The weighted arrow insert  100  may be formed from separate structures including the collar  110 , the tapered head  112  and the base  114  or may be formed as a monolithic structure. When formed as a monolithic structure from relatively heavy metallic material such as, for example, stainless steel, tungsten alloys, and the like, the weighted arrow insert  100  may be formed on a lathe to precisely control shape, dimensions, and balance. 
     Additionally, the various components of weighted arrow insert  100  may be treated or coated with a variety of substances to enhance performance within the arrow  150 . For example, the collar  110  may be treated or coated with a friction reducing substance such as, for example, graphite, TEFLON™, etc. to facilitate passage through the arrow  150  while the base  114  may be treated or textured to increase friction within a nock bore  182  ( FIG. 3 ) of the nock  158  ( FIG. 2 ) of the arrow  150  for reasons described hereinbelow. 
     Referring now to  FIG. 2 , the arrow  150  generally includes an elongate hollow or tubular shaft  152 , a tissue piercing arrowhead  154  affixed to a front end  156  of the tubular shaft  152  and a nock  158  affixed to a rear end  160  of the tubular shaft  152 . A fletching assembly  162  is also affixed to the rear end  160  of the tubular shaft  152  to guide the arrow  150  during flight. The tubular shaft  152  can be formed from a variety of materials, including but not limited to aluminum or aluminum alloys, carbon or carbon composites, and the like. 
     As best shown in  FIG. 3 , the fletching assembly  162  includes four feathers or vanes  164 ,  166 ,  168  and  170  longitudinally affixed to an outer surface  172  of tubular shaft  152 . In addition to transferring energy received from a bowstring to the arrow  150 , the nock  158  is provided to releasably retain the weighted arrow insert  100  within the rear end  160  of tubular shaft  152  until the arrow  150  engages with a target. Although the exemplary embodiment illustrates the fletching assembly  162  having four feathers or vanes  164 ,  166 ,  168  and  170 , it is understood that the fletching assembly  162  can include any suitable number of feathers or vanes  164 ,  166 ,  168  and  170 . 
     The nock  158  includes a hollow cylindrical body  180  defining a bore  182  for receipt of the base  114  of the weighted arrow insert  100 . The cylindrical body  180  includes a front end  184  terminating at a front end face  186 . The hollow cylindrical body  180  has an external diameter of D3 while the bore  182  of the cylindrical body  180  had an internal diameter of d4 sized to receive the base  114  (having a diameter of D1) in a friction fit fashion. A tapered rear body  188  extends from a rear end  190  of the cylindrical body  180  and includes a rear body front face  192  and spaced apart fingers  194  and  196  extending rearwardly from the rear body front face  192 . The fingers  194  and  196  define a gap or slot  198  for receipt of a bowstring (not shown). 
     To assemble the arrow  150 , initially, the weighted arrow insert  100  is removably assembled to the nock  158  by inserting the base  114  of the weighted arrow insert  100  into the bore  182  of the hollow cylindrical body  180  of the nock  158  such that the collar flat rear end face  148  of the collar  110  of the weighted arrow insert  100  is flush with the front end face  186  of the cylindrical body  180  of the nock  158 . The weighted arrow insert  100  is thus releasably retained by the nock  158  until dislodged by impact with a target  300  ( FIGS. 6-9 ). The combined weighted arrow insert  100  and nock  158  are then assembled to the arrow  150  by applying a glue or other adhesive to the cylindrical body  180  and inserting the weighted arrow insert  100  and the cylindrical body  180  of the nock  158  into the rear end  160  of the arrow  150 . 
     Specifically, the rear end  160  of the arrow  150  includes a rear end face  200  and the tubular shaft  152  of the arrow  150  defines a through bore  202 . The cylindrical body  180  of the nock  158  is inserted into the through bore  202  until the front face  192  of the nock  158  is flush with the rear end face  200  of the tubular shaft  152 . It should be noted that, while the nock  158  is retained within the through bore  202  by a glue or adhesive, in some instances, such as, for example, when the orientation of the arrowhead  154  or the fletching assembly  162  need be precisely oriented respective to a bow handle or string (not shown), the nock  158  may be received within through bore  202  of the tubular shaft  152  in friction fit fashion. 
     Turning now to  FIG. 4 , the arrowhead  154  generally includes an arrowhead body  210  terminating in a forward tissue-penetrating tip  212  and a rearwardly extending shaft  214  extending from a rear end  216  of the arrowhead body  210  for attachment to the tubular shaft  152 . The arrowhead  154  additionally includes a plurality of cutting blades such as, for example, cutting blades  218 ,  220 ,  222 ,  224 . 
     An insert  230  is provided for assembling the arrowhead  154  to the tubular shaft  152 , wherein the insert  230  includes a hollow body  232  defining an internal bore  234 . The internal bore  234  may be smooth to receive the shaft  214  of the arrowhead  154  and be secured thereto by any suitable joining method, including gluing, welding, and the like. Alternatively, the shaft  214  of the arrowhead  154  may be threadably assembled to a threaded shaft  214  of the arrowhead  154 . The insert  230  additionally includes a flange  236  at a front end  238  of the hollow body  232 . The flange  236  seats against the front end  156  of the tubular shaft  152  when the hollow body  232  is inserted into the through bore  202  of the tubular shaft  152 . 
     In order to absorb and/or reduce the impact of the weighted arrow insert  100  against the insert  230 , a resilient member or spring  240  is provided within the through bore  202  in the front end  156  of the tubular shaft  152 . The resilient member may be provided in a form of a coil spring  240  or may include other resilient structures such as, for example, leaf springs, foam or other compressible materials such as polymers, and the like. These are chosen to be sufficient to absorb an impact asserted from the weighted arrow insert  100  against the insert  230  and preventing dislodgement thereof from the tubular shaft  152  upon impact with a target  300 . Preferably, a forward end  242  of the spring  240  is affixed to a rear end  246  of the hollow body  232  of the insert  230 . The spring  240  additionally acts as a vibration dampener to stabilize the arrow  150  during flight. 
     It should be noted that, while the weighted arrow insert  100  and the spring  240  are disclosed as supplied with, and assembled to, the arrow  150 , the weighted arrow insert  100  and the spring  240  may be provided together, separate from the arrow, to form a “penetrator” assembly  250  for use with a variety of arrows. 
     Referring now to FIGS.  1  and  5 - 9 , the use of the penetrator assembly  250  within the arrow  150  to increase or provided multiple kinetic energy impulses through arrowhead  154  upon impact with a target will now be described. 
     Referring initially to  FIG. 5 , the arrow  150  is fully assembled including the penetrator assembly  250 . The weighted arrow insert  100  is releasably retained within the through bore  202  at the rear end  160  of the tubular shaft  152  by the nock  158 . The spring  240  is secured to the insert  230  within the through bore  202  at the front end  156  of the tubular shaft  152 . With reference to  FIGS. 1 ,  3  and  5 , when an archer wishes to launch the arrow  150  towards a target, such as, for example, a game animal, the arrow  150  is positioned on a bow such that a bow string or cable (not shown) is positioned within the gap  198  created between the fingers  194  and  196  of the nock  158 . The bowstring or cable is then drawn rearward and subsequently released, transferring the energy generated by deformation of the bow to the arrow  150  through the nock  158 . This propels the arrow  150  forward at an initial velocity. 
     Referring to  FIG. 6 , as the arrowhead  154 , and more specifically the tissue penetrating tip  212 , hits and engages a target surface  300 , forward momentum of the arrow  150  is interrupted or slowed and the inertial energy of the weighted arrow insert  100  dislodges and releases the weighted arrow insert  100  from its frictional engagement with the nock  158 . The inertial energy of the weighted arrow insert  100  causes the weighted arrow insert  100  to travel through the through bore  202  of the tubular shaft  152  of the arrow  150  at substantially the same velocity of arrow  150  just prior to engagement with the target  300 . As noted hereinabove, the flat outer surfaces  126  and  128  on the collar  110  and the flat sections  136  and  138  of the tapered head  112  of the weighted arrow insert  100  allow for the passage of air over the weighted arrow insert  100  as the weighted arrow insert  100  travels forward through the shaft through bore  202  within the tubular shaft  152 . This prevents compression of air within tubular shaft  152  ahead of the weighted arrow insert  100  which may slow travel of the weighted arrow insert  100  as the weighted arrow insert  100  passes through the tubular shaft  152 , which would diminish the momentum of the weighted arrow insert  100 . 
     As best shown in  FIGS. 6 and 7 , the tissue-penetrating tip  212  and respective blades  218 ,  220 ,  222  and  224  of the arrowhead  154  penetrate and create a cut  310  into the tissue  300 . Function of the weighted arrow insert  100  within the arrow  150  is additionally described by a representative schematic diagram illustrated in  FIG. 9 . When the weighted arrow insert  100 , specifically the tip  116  of the tapered head  112 , initially engages with the rear end  246  of the spring  240 , the weighted arrow insert  100  imparts a first burst of kinetic energy (KE), defined by the formula KE=½mv 2  (where “m” is the mass of weighted arrow insert  100  and “v” is the velocity at time of impact with the spring  240 ), to the arrowhead  154  to overcome its inertia. This first burst of kinetic energy (KE) drives the arrowhead  154  an initial depth  320  ( FIG. 9 ) further into the tissue  300 . 
     With reference to  FIG. 8 , upon full compression of the spring  240  by the weighted arrow insert  100 , the weighted arrow insert  100  imparts a second burst of kinetic energy (KE) to the arrowhead  154  further driving the arrowhead  154  a subsequent depth  322  further into and through the cut  310  in the tissue  300 . These first and second bursts of kinetic energy imparted to the arrowhead  154  by the penetrator assembly  250  help ensure a complete pass through of the arrowhead  154  through the target tissue  300 . As noted hereinabove, the spring  240  buffers the insert  230  against the impact of the weighted arrow insert  100  to prevent the insert  230  and thus the arrowhead  154  from dislodging or breaking off from the tubular shaft  152  of the arrow  150 . 
     While not specifically shown, a minor third burst of kinetic energy is imparted to the arrowhead  154  by expansion of the spring  240  back to its original uncompressed state. The forward momentum of the weighted arrow insert  100  acts as a base during expansion of the spring  240 , driving the arrowhead  154  a further slight distance forward. 
     Although the weighted arrow insert  100  includes a series of flat sections  136 ,  138  it is understood that the weighted arrow insert  100  may include a through bore (not shown) providing the same function for passage of air therethrough to reduce any compression of air entrapped within the arrow shaft through bore  202 . 
     The above-described embodiments are merely exemplary illustrations of implementations set forth for a clear understanding of the principles of the invention. Many variations, combinations, modifications or equivalents may be substituted for the elements thereof without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all the embodiments falling within the scope of the appended claims.