Aerial pyrotechnic device having high capacity shell
A single break shell has an elongated body provided with a convexly rounded upper end, a convexly rounded bottom end, and a midportion disposed between the two rounded ends. In a preferred embodiment, the shell is ellipsoidal in shape with the opposite ends having radius of curvature that are identical to one another. Other embodiments include variations on the basic elongated, rounded configuration. The shell is useful in both a self-propelled aerial pyrotechnic device in which the engine travels along with the shell, and an explosive lift charge type device in which the lift charge propels only the shell out of the launch tube after detaching from the lift charge.
 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
 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.
 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.
 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
 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;
 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;
 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;
 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;
 FIG. 5 is a longitudinal cross sectional view of the FIG. 4 embodiment; and
 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
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
1. A fireworks shell comprising a single pyrotechnic break having an elongated body provided with a convexly rounded top end, a convexly rounded bottom end, and a midportion disposed between said top and bottom ends.
2. A fireworks shell as claimed in claim 1,
- said midportion having an outer wall that is convexly rounded in both a longitudinal dimension of the body and a transverse dimension of the body.
3. A fireworks shell as claimed in claim 1,
- said top and bottom ends having substantially the same radius of curvature.
4. A fireworks shell as claimed in claim 3,
- said body being substantially ellipsoidal.
5. A fireworks shell as claimed in claim 1,
- one of said ends having a greater radius of curvature than the other of said ends.
6. A fireworks shell as claimed in claim 5,
- said body being substantially egg-shaped.
7. A fireworks shell as claimed in claim 5,
- said end with the greater radius of curvature comprising said top end.
8. A fireworks shell as claimed in claim 1,
- said midportion having an outer wall that is cylindrical.
9. A fireworks shell as claimed in claim 1,
- said shell comprising part of a device having an onboard engine for propelling the device and that travels with the shell during flight.
10. A fireworks shell as claimed in claim 1,
- said shell comprising part of a device having a lift charge that when detonated separates the shell from the lift charge to propel the shell in flight.
Filed: Jun 12, 2002
Publication Date: Dec 18, 2003
Inventor: Gregory P. Shelton (Eagleville, MO)
Application Number: 10171563
International Classification: F42B004/00;