Patent Publication Number: US-2003236141-A1

Title: Broadhead arrowhead

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] This invention relates to arrows and arrowheads. More particularly, the invention relates to arrowheads of the type commonly referred to as “broadhead” arrowheads typically, but not exclusively, used by hunters. 
     
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
     [0003]FIG. 1 shows a side perspective view of the broadhead arrowhead of this invention;  
     [0004]FIG. 2 shows an end view of the broadhead arrowhead looking rearwardly from the forward end of the arrowhead.  
     [0005]FIG. 3 shows a side detail view of the arrowhead.  
     [0006]FIG. 4 shows a detailed view of one of the blade assemblies of the arrowhead.  
     [0007]FIG. 4A shows the curvature of the blade assembly at three sections taken along section lines “A-A”, “B-B”, “C-C”, respectively, in FIG. 4.  
     [0008]FIG. 5 shows the broadhead arrowhead mounted to an arrow shaft. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0009] Referring to the drawings, the broadhead arrowhead of this invention comprises a body or ferrule  102 . At one end, called, for convenience, the proximal end, ferrule  102  incorporates a first, or head, end portion  104 . End portion  104  typically tapers to a point  105 . Ferrule  102  also has second, or distal, end portion  106 . End portion  106  may be slightly flared outwardly. It is not necessary that end portion  106  be flared outwardly. In some embodiments, end portion  106  may continue substantially straight to the rear end of body  102 . Ferrule  102  is typically symmetrical about a longitudinal axis  118  between first end portion  104  and second end portion  106 .  
     [0010] A mounting stub  108  extends rearwardly from distal end portion  106  of arrowhead body  102 . Typically, stub  108  is symmetrical about and coaxial with longitudinal axis  118 . Mounting stub  108  is intended to fit into a mating recess typically located at one end of a standard arrow shaft. Stub  108  may be threaded to mate with matching threads in the arrow shaft recess or it may be seated in the recess in a press fit arrangement. Alternatively, mounting stub  108  may be glued or otherwise sealed into the mating recess of the arrow shaft.  
     [0011] In other variations of mounting means, instead of a stub  108 , distal end  106  of ferrule  102  may be hollowed out to fit over an arrow shaft. In such an arrangement, the inside of hollow distal end  106  may be threaded to mate with threads on the outer suface of the arrow shaft; or distal end  106  may be press fit over the arrow shaft. Alternatively, distal end  106  may be fitted over the end of the arrow shaft and glued or otherwise sealed to the arrow shaft.  
     [0012] One or more blade assemblies  110  extend laterally outwardly from ferrule  102 . Preferably the arrowhead is constructed with two, three or four blade assemblies. Typically, if two blade assemblies are used, they are disposed substantially diametrically opposite each other about longitudinal axis  118  of ferrule  102 . Three blade assemblies are typically disposed at angles of approximately 120° around longitudinal axis  118 . Correspondingly, four blade assemblies  110  are typically mounted at 90° angles relative to each other about horizontal axis  118 .  
     [0013] Blade assembly  110  is shown in detail in FIGS. 1 and 4. Each blade assembly  110  comprises a first substantially planar blade assembly portion  112  and a second blade assembly portion  114 . A leading edge  113  of first portion  112  is typically sharpened to better allow the arrowhead to penetrate a target. First blade assembly portion  112  may comprise a solid substantially flat planar portion or optionally may have a cutout section  116 . Second blade assembly portion  114  extends rearwardly from first blade assembly portion  112 . Second blade assembly portion  114  is preferably curved, with a radius of curvature optimally between about 0.2″ and 0.5″, giving the blade the characteristics of an airfoil. The radius of curvature may vary over the surface of the blade. A trailing edge  119  of the blade is at an angle to arrowhead body  102 . This angle may be as great as 45 degrees or more, but optimally it increases from approximately 5 degrees to approximately 35 degrees at the blade tip. The blades, acting together, form an axial-flow turbine.  
     [0014] As shown in FIG. 3, second blade assembly portion  114  is joined to first blade assembly portion  112  by a continuously curved region  120 . The radius of curvature of region  120  is in the range of between about 0.2″ and 0.5″. An angle θ generally defines the angle between first planar portion  112  and second planar portion  114 . This angle θ is in the range of between about 5° and 25°. This configuration gives the blade assembly an airfoil-type shape. The length of first substantially planar portion  112  is between about 50% and 80% of the total length of blade assembly  110 . Correspondingly, second substantially planar portion  114  comprises between about 20% and 50% of the total length of blades assembly  110 . It will be understood by those skilled in the art that where the arrowhead has more than one blade assembly  110 , each blade assembly portion  114  is preferably angled relative to each corresponding blade assembly portion  112  in the same direction and at substantially the same angle for each blade assembly  110 .  
     [0015] Alternatively, first planar portion  112  and second angled planar portion  114  may be joined at a more sharply defined angle θ with a radius of curvature close to or at “0”. However, this alternative configuration does not produce the same high quality of aerodynamic effects as does the airfoil shape shown in FIG. 3.  
     [0016]FIG. 4A shows the curvature of the blade assembly  110  at three sections taken along section lines “A-A”, “B-B”, “C-C”, respectively, in FIG. 4.  
     [0017] Arrowhead body  102  and blade assemblies  110  may be made of any suitable material, such as, but not limited to, steel, aluminum, plastic, etc. As shown in FIG. 4, planar portion  112  of blade assembly  110  has a short extension  117  that fits into a slotted opening in ferrule  102 . Extension  117  extends from the inner edge of planar portion  112  substantially up to but just short of curved region  120 . Extension  117  may be glued, welded or soldered to the slot in body  102 . Alternatively, blade assembly  110  and body  102  may be integrally formed as by molding. Other techniques for securing blade assembly  110  to body  102  would be apparent to those skilled in the relevant arts.  
     [0018] In summary, each blade assembly  110  comprises a substantially flat planar portion  112  extending laterally outwardly of body  102  and substantially parallel to longitudinal axis  118 . A second blade assembly portion  114  is angled at an angle of between about 5° and 25° out of the plane of section  112  away from alignment with axis  118  and at an angle of between about 5° and about 45° to the ferrule body  102 . FIG. 2 shows end portions  114  of each blade angled slightly clockwise relative to the major plane of section  112 . Alternatively, end portions  114  can be angled slightly counterclockwise relative to the major plane of section  112 .  
     [0019] In the embodiment shown, each blade assembly  110  has the general shape of a substantially triangular or delta wing configuration. In other embodiments, blade assembly  110  can have the general shape of a swept wing or straight wing.  
     [0020] Much like the control surfaces of an aircraft wing, the ratio of angled portion length to overall blade assembly length can be relatively small. For example, in one embodiment, the ratio of the length of angled portion  114  to the overall length of blade assembly  110  is in the range of between 10% and 50%, and preferably between about 20% and 50%.  
     [0021] Each blade of the broadhead arrowhead incorporates a substantially similar airfoil that produces a rotational torque about longitudinal axis  118 . In flight, these forces induce a rapid rotation of the arrow about longitudinal axis  118  while minimizing aerodynamic drag. The plane of each blade assembly  110  remains parallel to the shaft of the arrow along its cutting edge  113 .  
     [0022] One of the features of the arrowhead of this invention is its ability to produce stabilized arrow flight without the use of fletching or tail fins (or feathers). FIG. 5 shows the broadhead arrowhead of this invention mounted to an arrow shaft  122  without fletching. Tests have shown that an arrow using the broadhead of this invention without fletching tracks true in flight and does not deviate significantly from the planned flight course. This is due to the rotation induced in the arrow by the aerodynamically designed broadhead blades, which is sufficient to stabilize the arrow in flight. Eliminating the fletching in fact improves flight characteristics because the rotational drag normally induced by the fletching is avoided. It should be noted, however, that the arrowhead of the invention can be used with fletched arrow shafts, as well.  
     [0023] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.