Study on the Effect of Leg Wire Attachment on the Height Attained by Aerial Shells

K.L. and B.J Kosanke

ABSTRACT: In many electrically discharged fireworks displays, it is a common practice to securely attach the electric match leg wires to both the aerial shell and to the firing mortar or mortar rack. When this is the case, it is necessary for the aerial shell to sever the attachment to the mortar or rack upon the firing of the shell. Usually this is accomplished by severing (tearing) the leg wires themselves. In this process, some of the kinetic energy of the shell is consumed, resulting in a reduction in the burst height that would otherwise have been achieved. This reduction in burst height will be greatest for those shells possessing the least kinetic energy (i.e., the smallest and lightest of the aerial shells). While experience has shown that the amount of reduction in burst height apparently does not present a significant safety hazard, the question remains as to how much reduction actually results. In a brief study of this question, it was concluded that for even the smallest and lightest aerial shells commonly used in displays (75 mm with a mass of 90 g) the reduction in burst height is on the order of 12%, and this decreases to about 1% for mid-sized aerial shells (150 mm with a mass of 1.1 kg).

Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 46-49

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