Archive for June 2007

Aerial Shell Drift Effects: A) The Effect of Long Mortars B) The Effect of Capsule-Shaped Shells

K. L. and B. J. Kosanke, A. L. Bauer and . E. R. Mutascioke

Abstract: Aerial shell drift is defined as the difference between the ballistically predicted trajectory of a shell and its actual trajectory. It had been speculated that longer length mortars and capsule-shaped shells might experience significantly different drift than normal length mortars and spherical shells. While longer mortars propelled 6-inch (155-mm) aerial shells to greater heights, the average shell drift was unaffected. Further, it was found that 6-inch (155-mm) capsule-shaped shells probably drifted slightly more than spherical shells.

Key Words: aerial shell drift, mortar length, shell shape.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 44-48
(K4_44)
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Explosive Limit of Armstrong’s Mixture

K. L. and B. J. Kosanke

When investigating the cause of an accident, it was necessary to learn something about the lower explosive limit with regard to phosphorus content in Armstrong’s Mixture. A short literature search did not produce the needed information; thus a brief laboratory study was undertaken. Because the results of the study may be useful regarding safety and because they may be intrinsically interesting, this short article was prepared.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 42-43
(K4_42)
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Hazardous Chemical Combinations: A Discussion

Clive Jennings-White and K. L. Kosanke

ABSTRACT: All pyrotechnic compositions present some hazard due to their ability to produce energy. However, some compositions pose an added hazard because of the combination of incompatible materials. The use of such compositions may result in more frequent accidental ignitions during processing or spontaneous ignitions during storage. Other compositions pose an added hazard because of their ability to produce especially large amounts of energy with rapid reaction rates. The use of such compositions is likely to result in especially powerful explosions in the event of an accidental ignition.

This article attempts an organized examination of some combinations of commonly used pyrotechnic chemicals that are believed to have significantly increased hazard potentials.

Keywords: accidental ignition, spontaneous ignition, hazardous combinations, chemicals, compatibility, incompatibility


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 28-41
(K4_28)
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Concussion Mortar Internal Pressure, Recoil and Air Blast as Functions of Powder Mass

K. L. & B. J. Kosanke

ABSTRACT: A concussion mortar is a device used to produce jarring explosive sounds at events such as concerts and other theatrical productions. It consists of a heavy steel bar, drilled out to produce an explosion chamber. A type of pyrotechnic flash powder is loaded into the explosion chamber and fired with an electric match. Although concussion mortars are used quite frequently, for the most part, detailed measurements of their manner of functioning have not been reported in the literature. In the present study of concussion mortars, internal mortar pressure, recoil force and air blast were measured as functions of concussion powder load. It was determined that a full load (1 oz. or 28 g) of a strontium nitrate and magnesium concussion powder produced peak internal pressures averaging approximately 3100 psi (21 MPa). It was also observed that the width of the pressure peak ranged from approximately 7 ms for light loads, down to less than 2 ms for heavy loads. The recoil produced for a full load averaged approximately 5.9 lbf·s (26 N·s). The air blast for a full load, at a point 5 feet from and 3 feet above the mortar (1.52 m and 0.91 m, respectively), averaged approximately 1.5 psi (10 kPa). In addition, there were a number of unexpected observations, some of which have not been fully explained at the time of this writing.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 16-27
(K4_16)
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Fireworks and their Hazards

Thomas J. Poulton, M.D and Kenneth L. Kosanke, Ph.D.

“What are fireworks like?” she had asked.

“They are like the Aurora Borealis,” said the King, “only much more natural. I prefer them to stars myself, as you always know when they are going to appear….”                Oscar Wilde, The Remarkable Rocket.

Although appreciative audiences may value the predictability of fireworks, firefighters, unlike the king in The Remarkable Rocket, know that on occasion they may not be so reliable. When the first-due company finds it is dealing with fireworks, it is in an unusual situation that requires specific technical knowledge to ensure the safest possible outcome.

Scope of the Challenge: During the past 15 years, the quantity of fireworks used in the United States has more than doubled to approximately 100 million pounds annually. Although fireworks remain most popular over the Fourth of July holiday, their use is now common throughout the year at theme parks, fairs, and public events. Performing artists have greatly expanded the use of pyrotechnic displays to enhance the entertainment value of concerts, plays, and other stage productions. In a recent year, the U.S. Fire Administration reported that approximately 6,000 (less than one percent) of the almost one million fires occurring in the United States involved fireworks. The average loss per incident was less than $2,000.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 4-15
(K4_4)
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Stars Blown Blind

K.L. and B.J Kosanke

When an aerial shell bursts, stars that fail to burn are often said to be “blind stars”, or more descriptively as having been “blown blind”. This detracts from the beauty of the shell and contributes to debris fallout. The problem can be caused by any of a combination of factors; the most important of these are the degree of violence of the shell burst and the burn characteristics of the stars.

In simplest terms, a star will ignite when its surface has been raised to its ignition temperature. The star will continue to burn only so long as the burning surface feeds sufficient energy to the next deeper layer of the star, to raise that unignited composition to its ignition temperature. (See Figure 1.) (For a more complete discussion of pyrotechnic ignition and propagation, see reference 1.)


 Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 1-4
(K4_1)
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