Archive for March 2007

Factors Affecting the Precision of Choreographed Displays

K.L. and B.J Kosanke

For maximum effectiveness of tightly choreographed fireworks displays, it is important that shell bursts occur very near their intended times. For the purpose of this article, it is assumed that electrical firing employing a computer or other means of accurately applying the firing current to electric matches is being used. In addition, it is assumed that the choreographer has accurate information about the firing and burst characteristics of the shells being used, and that no errors are made in the design of the choreography or in the loading of the display. In that combine to affect the overall precision of the shell burst times. First is the preciseness of the shell firings from their mortars; second is the preciseness of the time fuse burning. (In the context of this article, “preciseness” is intended to indicate consistency or reproducibility of events.)


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 59-60
(K6_59)
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Electric Matches: Effective Thermal Output

K.L. and B.J Kosanke

Introduction: A study of electric match sensitiveness and performance has recently been completed, and a summary of the results is being presented as a series of short articles. This is the ninth article in the series[1] and presents the results of tests to determine the effective thermal output for the same collection of 10 electric match types as in the previous articles.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 57-58
(K6_57)
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The Effect of Mortar Diameter on the Burst Height of Three-Inch Spherical Aerial Shells

K. L. and B. J. Kosanke

Background: A while ago, a small fireworks display company called seeking information about the effect of mortar internal diameter on the burst height expected to be achieved by aerial shells fired from them. It seems the company had received a large quantity of three-inch, high-density polyethylene (HDPE) pipe that they had cut into 18- inch lengths for mortars (including 1.5-inch thick plugs) before having checked the pipe’s internal diameter. When it was checked, the HDPE pipe was found to have an internal diameter of 3.21 inches (i.e., it was significantly oversize). Because it was close to the July 4th holiday season, there was not sufficient time to replace the pipe. Accordingly, the question was, could these mortars be safely used?


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 54-56
(K6_54)
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The Effect of Ignition Stimulus on Aerial Shell Lift Performance

K.L. and B.J Kosanke

ABSTRACT: It had been speculated that the replacement of fierce burning quick match shell leaders with electric matches might have contributed to the production of a significant number of low breaking aerial shells experienced by a small fireworks display company. A preliminary study of the effect of ignition stimulus level did not supporting the theory that the weaker stimulus provided by electric matches (possibly in conjunction with Chinese lift powder) was the reason for the low breaking shells. However, that study was thought not to be sufficiently conclusive to completely settle the question. Accordingly, a more extensive series of tests were subsequently performed. For these tests, because of the lack of sufficient Chinese lift powder, Goex (USA) Black Powder was used. The result of these tests was that again no effect was observed for the flight times of the test aerial shells. The average flight times for groups of approximately 30 of the 75- mm (3-in.) test shells was 9.65 ± 0.13 seconds and 9.58 ± 0.17 seconds for shells using quick match and electric match firing, respectively.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 50-53
(K6_50)
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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
(K6_46)
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Floating Dud Aerial Shells

K.L. and B.J Kosanke

Introduction: Over the past 25 years, the percentage of spherical aerial shells that fall to the ground as duds after firing has substantially decreased. (This is especially true for shells from China.) Obviously this is a good thing, and it is a result of such things as improvements in the quality of the time fuses being used and the methods of their priming, and because of the near universal adoption of redundant fusing techniques.[1] However, the improvement has not been so great as to reduce the percentage of dud shells to zero. Nonetheless, the reduction in the number of dud shells, in conjunction with the use of substantially increased separation distances introduced approximately 15 years ago.[2] combine to afford a high level of spectator protection from dud shells during typical displays.[3,4] Further, the increased attention to dud searches both immediately following and at first light on the morning after land-based displays has mostly eliminated accidents resulting from dud shells left behind to be found by children.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 42-45
(K6_42)
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Faversham’s Gunpowder Mills

K.L. and B.J Kosanke

Recently, while in the United Kingdom and between teaching pyro-chemistry short courses, we took a side trip to visit the restored Chart gunpowder mill. This is the only restored mill from what was once a collection of approximately ten powder mills near the town of Faversham in Kent county. When operating at their peak in 1792, these mills produced over 25,000 barrels of powder.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 38-41
(K6_38)
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Chlorate Compositions in Quickmatch

K.L. and B.J Kosanke

After the 1999 PGI convention, the authors were told about a type of quick match that had been sold at the convention and which was suspected of being made using a chlorate oxidizer. The individual’s suspicion was based on his perception of its extremely fast burn rate. Subsequently, a sample of that fuse was spot tested and found to contain a nitrate but not a chlorate. Sometime later, the authors were given a sample of quick match thought to be of the same type. The burn rate of the quick match was observed to be most vigorous; however, there was not a sufficient amount for the authors to make a usefully quantitative measurement of its burn rate. Small amounts of the composition were removed from the black match portion of this fast burning quick match, and two tests for the presence of chlorate were performed. The first test was the concentrated hydrochloric acid test, in which a few drops of the acid are placed on the composition. The presence of a chlorate is revealed by a modest rate of chlorine dioxide gas production, with its characteristic color and odor.[1,2] The second test was the analine-HCl spot test, in which some of the composition is dissolved in a tiny amount of water, the water is decanted and treated with a drop of analine-HCl test reagent.[1,3] The presence of a chlorate is revealed by the appearance of first a red then blue color. Again, both test results were negative for the presence of a chlorate. Accordingly, another possible explanation for the vigorous burn rate of the quick match was sought.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 35-37
(K6_35)
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Hypotheses Regarding Star-Shell Detonations

K.L. and B.J Kosanke

ABSTRACT: Fireworks star shells occasionally explode upon firing while they are still inside the mortar. Most often, this occurs with approximately the same level of violence as when the shell explodes after having left the mortar, and often even relatively weak mortars survive the experience intact. While unnerving to the firing crew, this represents relatively little hazard for crew or spectators. However, on rare occasion, the in-mortar star shell explosion achieves a level of violence substantially greater than normal. These more powerful explosions represent a potentially life-threatening hazard for both the firing crew and spectators. Unfortunately, the cause for these more violent explosions has not been definitively established, and without knowing the cause, relatively little can be done to prevent them from happening. In this article, two hypotheses are suggested as possible explanations for these dangerous malfunctions. Basic information and some empirical evidence are presented in support of two potential theories.

Keywords: aerial shell explosion, aerial shell malfunction, in-mortar explosion, flowerpot, star-shell-detonation, VIME


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 26-34
(K6_26)
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Pyrotechnic Reaction Residue Particle Identification by SEM / EDS

K. L. Kosanke, B. J. Kosanke & Richard C. Dujay

ABSTRACT: Today the most reliable method for detecting gunshot residue is through the combined use of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of the resulting X-rays. In recent years, this same methodology has found increasing use in detecting and characterizing pyrotechnic reaction residue particles (PRRPs). This is accomplished by collecting particulate samples from a surface in the immediate area of the pyrotechnic reaction. Suspect PRRPs are identified by their morphology (typically 1 to 20 micron spheroidal particles) using a SEM, which are then analyzed for the elements they contain using X-ray EDS. This will help to identify the general type of pyrotechnic composition involved. Further, more detailed laboratory comparisons can be made using various known pyrotechnic formulations.

Keywords: pyrotechnic reaction residue particles, PRRP, primer gunshot residue, PGSR, scanning electron microscopy, SEM, energy dispersive spectroscopy, EDS, morphology, X-ray elemental analysis, forensics


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 6, (2001-2002), pp 12-25
(K6_12)
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