Abstract:
A multiple stage pyrotechnic shell apparatus is disclosed. The invention has enhanced efficiency to increase lift and reduce the risk of one or more of the charges from exploding near the ground. The enhanced efficiency is obtained through the novel use of shaped breaks that conform to the shape of the inner surface of the shell&#39;s launch tube, and in particular through the use of cylindrically shaped breaks in round launch tubes. In addition, the present invention further enhances efficiency by configuring the breaks such that all the breaks weigh the same or the upper breaks weigh more than the lower breaks in the launch tube.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This nonprovisional patent application claims priority to the provisional patent application having Ser. No. 60/485,914, which was filed on Jul. 10, 2003. 

   BACKGROUND OF THE INVENTION 
   The invention relates to a new pyrotechnic shell apparatus, and more particularly to a multiple stage pyrotechnic shell apparatus having enhanced efficiency to increase lift and reduce the risk of one or more of the charges from exploding near the ground. 
   Multiple stage pyrotechnic shells typically comprise two or more pyrotechnic modules, known as “breaks” that are housed within a single launch tube. A launch charge is located in the tube below the breaks. The breaks are linked to one another and intended to sequentially discharge and produce a pyrotechnic effect once the breaks are launched a safe distance into the sky by the launch charge. Typically each of the breaks is configured in a spherical shape. 
   Unfortunately, the spherical shape of the breaks in a conventional multiple stage pyrotechnic shell allows the expanding gases from the launch charge to escape between the breaks and the inner surface of the launch tube, resulting in substantial loss of pressure during launch. This limits the launch height of a conventional multiple stage pyrotechnic shell. The limited launch height of a conventional multiple stage pyrotechnic shell therefore presents a greater risk of unacceptable and dangerous low-level discharge of the individual breaks. 
   In addition, in a conventional multiple stage pyrotechnic shell, the powder weight varies between the breaks in the shell. In particular, traditionally, the break nearest the bottom of the shell has the most powder weight, with each successive break above the bottom break having a successively lower powder weight. This causes the grouping of breaks to tumble during flight and the resultant inefficiency further hinders the ability of the breaks to attain maximum height, and also adds to the risk of unacceptable and dangerous low-level discharge of the individual breaks. 
   U.S. Pat. No. 6,383,033, for example, discloses a multiple stage pyrotechnic shell apparatus having three breaks. In order to minimize the potential for tumbling, the &#39;033 Patent discloses that the breaks are all uniaxial and the weights of the three breaks are distributed along the central axis such that the center of gravity of the shell is below the vertical midpoint. The shell apparatus of the &#39;033 Patent is further restricted to having a total break weight of less than 40 grams. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention comprises a fireworks shell that includes two or more breaks, where each said break is coupled to at least one other break. The breaks each contain a break charge and a break effect, and each break has a specific outer perimeter. Preferably, the breaks are attached to one another in a sequential fashion so as to form a single linear grouping. Fuses are located between the individual breaks, linking the break charges of adjacent breaks. 
   A launch tube, having a specific interior cross-section, houses at least one of, and preferably all of, the individual breaks. The shape of the interior cross-section of the tube and the outer perimeter of at least one of the breaks contained in the tube are configured such that the perimeter of the break is elongated and has a cross-section essentially equivalent in shape to the interior cross-section of said tube. 
   In the preferred embodiment, the interior surface of the tube is cylindrical and the shape of the break at the bottom of the tube is likewise cylindrical, but of a slightly smaller diameter, such that upon ignition of the launch charge located below the bottom break, a greater amount of the expanding gases will more efficiently propel the breaks into the air above the shell than in a conventional shell having round breaks. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects of the invention are achieved as set forth in the illustrative embodiments shown in the drawings that form a part of the specification. 
       FIG. 1  is a partial cut-away perspective view of the preferred embodiment of the present invention having three coaxial breaks with the first break being cylindrical in shape; 
       FIG. 2  is a cross-sectional view of the preferred embodiment of the present invention having three coaxial breaks with the first break being cylindrical in shape; 
       FIG. 3  is a cross-sectional view of another embodiment of the present invention having four coaxial breaks with the first two breaks being cylindrical in shape; 
       FIG. 4  is a cross-sectional view of yet another embodiment of the present invention having four coaxial breaks with the first and third breaks being cylindrical in shape; 
       FIG. 5  is a cross-sectional view of yet another embodiment of the present invention having three coaxial breaks with the first and third breaks being cylindrical in shape; 
       FIG. 6  is a cross-sectional view of yet another embodiment of the present invention having three coaxial breaks with the second break being cylindrical in shape. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The multiple stage pyrotechnic shell apparatus of the preferred embodiment is indicated generally at  10  ( FIG. 1 ). The shell  10  includes a tube  12 , a generally flat base  14  positioned below the tube  12  and joined with the bottom of the tube  12 , and a base plug  16  that is integral with and extending from the base  14 , the plug  16  configured to fit snugly within and being secured to the inner surface of the bottom of the tube  12 . 
   Three pyrotechnic breaks  18 ,  20 ,  22  are positioned sequentially within the tube  12 , the cylindrical break  22  being positioned at the bottom of the tube  12  and the round breaks  18 ,  20  positioned above the break  22 . The breaks  18 ,  20  are joined together with a paper connect  24  and the breaks  20 ,  22  are joined together with a paper connect  26 . A lift charge compartment  28  is attached to the bottom of the cylindrical break  22  and rests against the top of the plug  16  within the tube  12 . 
   A fuse  30  extends from the interior of the lift charge  28 , to the inner surface of the tube  12 , then extends upward through the tube  12  between the breaks  18 ,  20 ,  22  and the inner surface of the tube  12 . At the top of the break  18 , the fuse  30  extends from the inner surface of the tube  12  through a fuse holder loop  32  attached to the top of the break  18 . The fuse holder loop  32  is constructed of string. From the fuse holder loop  32 , the fuse  30  extends up and out of the top of the tube  12 . 
   Referring to  FIG. 2 , it can be seen that each of the breaks  18 ,  20 ,  22  includes a housing  34 ,  36 ,  38 , respectively, such that each housing  34 ,  36 ,  38  contains a break charge  40 ,  42 ,  44 , respectively. The break charges  40 ,  42 ,  44  may be comprised of a number of combustible materials, including for example, a mixture of 70% Potassium Nitrate (KNO3), 5% Surfer (S) and 25% Carbon (C). (See Chart 5 of Appendix A; Appendix A being attached hereto and incorporated by reference herein). Similarly, the lift charge compartment  28  includes a housing  29  that contains a lift charge  31 . The lift charge  31  contained within the lift charge compartment  28  may also be comprised of a number of combustible materials, including for example, a mixture of 70% Potassium Nitrate (KNO3), 5% Surfer (S) and 25% Carbon (C). (See Chart 5 of Appendix A). 
   Each of the breaks  18 ,  20 ,  22  also includes one or more effects  41 ,  43 ,  45  contained within the housing  34 ,  35 ,  38  respectively. Effects are pyrotechnic compositions that burst into various colors and configurations upon combustion. For example, in addition to being one or more of numerous colors, the effect may be glittering, spinning, exploding, etc. As would be readily understood by one of ordinary skill in the art, the effects  41 ,  43 ,  45  may be comprised of a number of combustible materials. For example, a mixture of 43% Potassium Perchlorate (KclO4), 20% Sodium Oxalate (Na2C2O4), 10% Strontium Nitrate (Sr(NO3)2), 20% Al-Mg Alloy (Magnalium) and 7% Penolic Resin (Resinox) will produce a golden effect. (See Chart 5 of Appendix A). 
   As the charts contained in Appendix A reveal, the combined weight of the pyrotechnic composition for a single shell of the preferred embodiment, including break charges and effects, totals between 52.2 and 56.2 grams, depending on the specific combination of charges and effects in the shell. Because the lift charges will range between 6 to 10 grams, the total weight of a shell, including the lift charge weight, can exceed 60 grams, if authorized by regulations. 
   A paper fuse  46  extends from the lower portion of the break charge  40  in the break  18  to the upper portion of the break charge  42  in the break  20 . The fuse  46  is surrounded about its midsection by a primer  48 . A second paper fuse  50  extends from the lower portion of the break charge  42  in the break  20  to the upper portion of the break charge  44  in the break  22 . The fuse  50  is surrounded about its midsection by a primer  52 . A third paper fuse  54  extends from the lower portion of the break charge  44  to the upper portion of the lift charge  31  in the lift charge compartment  28 . The fuse  54  is surrounded about its midsection by a primer  56 . 
   As can be readily seen and understood, prior to operation, a user will place the shell apparatus  10  on a generally flat surface outdoors, positioned with the base  14  set flat against the ground surface and the open end of the tube  12  facing upward. When the user applies an ignition source to the fuse  30  atop the tube  12 , the fuse  30  will burn down into the tube  12 , through the fuse holder loop  32 , down the inner side of the tube  12  along the breaks  18 ,  20 ,  22 , and into the lift charge housing  29 , where the fuse  30  ignites the lift charge  31 . 
   The combustion of the lift charge  31  causes an explosion below the break  22  that generates high pressure from the gases expelled during the explosion. As can be appreciated, owing to the cylindrical shape of the break  22 , the housing  38  of the break  22  is in close proximity to the inner sidewall of the tube  12  for a substantially greater length than in conventional pyrotechnic shells having only round breaks. The break  22  therefore allows very little of the expanding gases escape between the break  22  and the inner surface of the tube  12 . In contrast, conventional pyrotechnic shells incorporate round breaks that allow a much greater volume of expanding gases to escape because the length of the gap between the round break and the inside of the tube is so short. Hence, the novel design of the present invention dramatically increases the efficiency of the pyrotechnic shell  10  over conventional shells that exclusively utilize round breaks. 
   The novel design of the present invention also enables the total weight of the breaks in a single shell to exceed the present weight limit of 40 grams in conventional multiple stage pyrotechnic shells. 
   In addition, the upper breaks in a conventional multiple stage pyrotechnic shell would weigh less than the lower breaks. In certain embodiments of the present invention, however, the upper breaks may weigh the same, or even more, than the bottom break  22 . This creates more stability among the breaks during flight, thereby reducing the inefficiencies of drag caused by tumbling, as occurs in conventional shells. 
   As can be seen from  FIGS. 3-6 , the application of the novel use of cylindrical breaks in a multiple stage pyrotechnic shell is not limited to either the use of only one cylindrical break, or restricting the location of the cylindrical shell to the bottom of the tube. Rather, other embodiments of the present invention are considered. For example, there may be more than one such cylindrical break in a single pyrotechnic shell. ( FIGS. 3-5 ). There may be more than three breaks in a single shell; e.g. four breaks in each shell. ( FIGS. 3-4 ). A cylindrical break may be placed in positions other than at the bottom of the tube. ( FIGS. 3-6 ). Further, all of the breaks may be cylindrical. 
   In addition, the diameter of the tube and the breaks may vary so long as the outer diameter of at least one of the cylindrical breaks is slightly less than the inner diameter of the tube. Of course, there may be more than four breaks in each tube. One or more of the breaks may be placed in the tube without being rigidly attached to other breaks. The breaks may be of different shapes so long as at least one of the breaks is shaped to have an extended portion of its outer surface the same shape as, but slightly smaller than, the inner shape of the tube. For example, cross-section of the tube may be square, oval, or some other shape. If the cross-section of the tube is square, at least one of the breaks would need to likewise be essentially square, but with a perimeter slightly smaller than the perimeter of the inner surface of the tube. 
   No base is required if the tube is configured to be closed at the bottom end. Of course, the base itself may be of any number of configurations including, but not limited to, the following:
         a. a simple plug at the base of the tube;   b. a flat plate with a circular groove cut in the top surface, where the groove receives the tube;   c. a simple flat plate to which the tube is attached with glue, some other adhesive, of with some other attachment means such as brackets or clips;   d. the bottom of the base may be irregular, for use on uneven surfaces;   e. a cavity may be formed in the base to house the lift charge;       

   The tube  12 , the break housings  34 ,  36 ,  38 , and the lift charge housing  29 , may all be comprised of a variety of materials, such as paper, plastic, metals, wood, or other material, so long as the material facilitates the proper operation of the pyrotechnic apparatus. The fuse  30  may exit the shell at locations other than through the top of the tube  12 . For example, the fuse  30  may exit the shell at any position along the side of the tube  12 , or through the base  14 . 
   Other configurations incorporating the novel use of one or more cylindrical breaks in a multiple stage pyrotechnic shell may be readily discerned by one of ordinary skill in the art.