Patent Publication Number: US-2003230211-A1

Title: Aerial pyrotechnic device having high capacity shell

Description:
TECHNICAL FIELD  
       [0001] This invention relates to pyrotechnic devices and, more particularly, to a specially shaped shell containing a pyrotechnic display which is useful in mortars, rockets and the like for entertainment purposes.  
       BACKGROUND AND SUMMARY  
       [0002] Class C aerial pyrotechnic devices are subject to governmental restrictions with respect to the amount of charge that can be carried by the product and its dimensions. Current regulations restrict the display charge and lift charge to a combined maximum total weight of 60 grams. Previously, the limit was 40 grams for the display charge, but newer regulations permit the display charge to exceed the 40 gram amount provided that the combined total between the display charge and the lift charge does not exceed 60 grams. Current regulations also restrict the diameter of the display charge to a maximum of 1.75 inches.  
       [0003] While it is possible to meet the 1.75 diameter limitation and maximize the display charge by having the shell cylindrical, it has been found that the shape of the display when it explodes in the sky is not a round starburst, which is preferred by most people. Thus, fireworks manufacturers tend to form the display charges as round balls, which explode into a round starburst when detonation occurs. However, a ball-shaped shell having a diameter of 1.75 inches contains less than 40 grams of display charge. Thus, even under the previous standard in which 40 grams was the maximum weight for the display charge, a certain amount of display charge was sacrificed in order to achieve the most desirable round starburst pattern.  
       [0004] The present invention contemplates stretching or elongating the round shape of the shell so that, while achieving a desirable rounded starburst pattern at explosion, the display charge capacity of the shell can be increased lengthwise without changing the transverse diameter of the shell or exceeding the 1.75 inches limitation. In its most preferred form, the elongated, rounded shell takes on the shape of an ellipsoid wherein opposite rounded ends of the shell have the same convex radius of curvature and the midportion of the shell has an outer wall that is convexly rounded in both a longitudinal dimension of the body and a transverse dimension of the body. Alternative shapes may include an egg shape in which one end of the shell has a larger radius of curvature than the other, and a combined rounded and cylindrical configuration in which the opposite ends of the shell are both rounded at the same radius while the midportion is cylindrical. The specially shaped shells may be employed in connection with an aerial device having an on board lift charge engine that travels with the shell during flight, or with a device having an explosive lift charge that causes the shell to separate from and be propelled upwardly away from the lift charge when the shell is launched. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0005]FIG. 1 is an isometric view of a self-propelled aerial pyrotechnic device with an on board lift charge engine and employing an elongated, rounded shell in accordance with the principles of the present invention;  
     [0006]FIG. 2 is an enlarged, fragmentary side elevational view of the device of FIG. 1 with portions broken away and shown in cross section to reveal details of construction, the illustrated embodiment comprising a shell having an ellipsoidal shape;  
     [0007]FIG. 3 is a fragmentary illustration of another embodiment of the invention showing an egg-shaped shell wherein one end, preferably the upper end, has a larger radius of curvature than the lower end;  
     [0008]FIG. 4 is an isometric view of an aerial device with an explosive lift charge employing an elongated, rounded shell in accordance with the principles of the present invention;  
     [0009]FIG. 5 is a longitudinal cross sectional view of the FIG. 4 embodiment; and  
     [0010]FIG. 6 is a longitudinal cross sectional view of an explosive lift charge type device employing another embodiment of an elongated, rounded shell wherein the midportion of the shell is cylindrical while the opposite ends are rounded. 
    
    
     DETAILED DESCRIPTION  
     [0011] The present invention is susceptible of embodiment in many different forms. While the drawings illustrate and the specification describes certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments.  
     [0012] The shell  10  illustrated in FIGS. 1 and 2 comprises part of a self-propelled aerial pyrotechnic device  12  having an on board lift charge engine  14 . Generally speaking, the device  12  is constructed in accordance with the principles set forth in certain of my earlier and patent applications, namely Ser. No. 09/482,579 filed Jan. 13, 2000 titled Aerial Fireworks Product; application Ser. No. 09/751,853 filed Dec. 29, 2000 titled Aerial Fireworks Product Having Synthetic Resinous Stabilizing Base; and U.S. Pat. No. 6,386,112 issued May 14, 2002 titled Aerial Pyrotechnic Product With Retarded Post-explosion Descent. Said prior U.S. applications and patent are hereby incorporated by reference into the present application.  
     [0013] As noted in the incorporated documents, device  12  is adapted to be launched from an upstanding launch tube (not shown) and stands upright while in such tube upon the legs  16 ,  18  and  20  of a stabilizing base  22  of the device. A long fuse  24  leads from a point above the shell  10  down the side of the device  12  and into the bottom of engine  14 .  
     [0014] paperboard cylinder  26  is fixed to the upper end of base  22  and projects upwardly therefrom to support the shell  10  at its upper end. The upper end of engine  14  projects into the lower, hollow interior of cylinder  26 , and a timing fuse  28  leads from the upper end of engine  14  into the interior of shell  10  for igniting the contents thereof after engine  14  has propelled device  12  to its intended altitude. Shell  10  is adhered to the upper end of cylinder  26  by a suitable bonding material (not shown) well understood by those skilled in the art.  
     [0015] Shell  10  comprises a single pyrotechnic break having an elongated body provided with a convexly rounded top end  30 , a convexly rounded bottom end  32 , and a midportion  34  disposed between top and bottom ends  30 ,  32 . In the most preferred embodiment, the shell body is substantially ellipsoidal, presenting an outer surface all plane sections of which are ellipses or circles. When the body is viewed in longitudinal cross section as illustrated in FIG. 2, it will be seen that the two-dimensional plane curve described by the exterior hull  36  of the shell presents an ellipse comprising a closed plane curve generated by a point moving in such a way that the sums of its distances from two fixed points is substantially constant. In this shape, the top and bottom ends  30 ,  32  have substantially the same radius of curvature, while the midportion  34  has an outer wall defined by the proximal portion of hull  36  that is convexly rounded in both a longitudinal dimension of the body and a transverse dimension of the body.  
     [0016] Hull  36  of shell  10  may be constructed of paper-mache, and the display charge  38  contained within hull  36  may take a variety of different forms as well understood by those skilled in the art. In one exemplary embodiment of the invention, the shell has a diameter across its mid-section of 1.50 inches and a length dimension from its top to bottom ends of 2.25 inches.  
     [0017] The aerial device  112  illustrated in FIG. 3 is substantially the same as the device  12  of FIGS. 1 and 2, except that the shell  110  is egg-shaped rather than ellipsoidal. In this respect, it will be seen that the radius of curvature of one end of shell  110  is significantly larger than the radius of curvature of the opposite end thereof. Preferably, but not necessarily, shell  110  has the top end  130  comprising the end with the larger radius of curvature, while the bottom end  132  has the smaller radius of curvature. In all other respects, shell  110  is the same as shell  10 .  
     [0018]FIGS. 4 and 5 show another embodiment wherein a shell  210  comprises part of an aerial pyrotechnic device  212  wherein the explosive lift charge  240  is initially attached to shell  210 . However, when lift charge  240  is detonated after placing device  212  within a launch tube (not shown), shell  210  separates from lift charge  240  and is projected upwardly out of the tube and to a sufficient altitude to permit its explosion.  
     [0019] Shell  210  is constructed identically to the shell  10  of FIGS. 1 and 2, having an upper end  230 , a bottom end  232 , and a midportion  234 . In the illustrated embodiment, shell  210  is substantially ellipsoidal in shape, although it could also be egg-shaped like shell  110  or cylindrical with rounded ends as will subsequently be described with respect to the embodiment of FIG. 6.  
     [0020] Shell  210  has a hull  236  containing a display charge  238 . A safety fuse  224  leads downwardly from about shell  210  and is embedded within the black powder charge  242  of lift charge  240 . A timing fuse  228  extends between the charge  242  of lift charge  240  and the display charge  238  within hull  236 . In one exemplary embodiment of the device  212 , shell  210  has a length dimension of approximately 1.50 and a transverse diameter of approximately 2.25.  
     [0021]FIG. 6 shows a shell  310  that is essentially cylindrical but has rounded ends. Shell  310  is illustrated by way of example in connection with a mortar type aerial device  312 .  
     [0022] Shell  310  has a rounded top end  330 , a rounded bottom end  332 , and a cylindrical midportion  334 . Both ends  330  and  332  have the same radius of curvature. Except for the combination cylindrical and rounded shape of shell  310 , the device  312  is identical to device  212 .  
     [0023] It will thus be seen that the shells of the present invention retain at least a substantial amount of rounded configuration to obtain the desirable rounded starburst pattern when the display charge explodes at the selected altitude. At the same time, due to the elongated nature of the shell, an additional amount of display charge can be contained within the hull without increasing the width or transverse diameter of the shell beyond the limit of 1.75 inches. Consequently, a bigger, yet aesthetically pleasing single break shell can be achieved without exceeding the current limits on charge weight and transverse diameter.  
     [0024] Although preferred forms of the invention have been described above, it is to be recognized that such disclosure is by way of illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention.  
     [0025] The inventor(s) hereby state(s) his/their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of his/their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.