Archive for May 2009

Flash Powder Output Testing: Weak Confinement

K. L. & B. J. Kosanke

ABSTRACT: A variety of flash powders were tested under weak confinement to determine the sound pressure levels and tonal characteristics produced. In these tests it was found that: the sound output from mixtures prepared with potassium perchlorate from four manufacturers are essentially equivalent; there are significant differences in the level of sound output as a result of using six different common aluminum powders; the addition of either of two common flow or bulking agents have essentially no effect on the sound produced; the substitution of potassium chlorate for potassium perchlorate in a common flash powder has essentially no effect on the sound produced; and the addition of antimony sulfide or sulfur reduces the duration of positive phase without increasing the level of the sound produced. In short, it was found that nothing surpassed the level of sound produced by a 70:30 mixture of reasonably high-quality potassium perchlorate and a high quality flake aluminum powder. This is significant because the use of potassium chlorate, antimony sulfide, and sulfur, can seriously increase the sensitiveness of flash powders to accidental ignition.

Keywords: flash powder, sound pressure level, blast pressure, weak confinement, positive phase


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 83-93
(K4_83)
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Simple Measurements of Aerial Shell Performance

K. L. & B. J. Kosanke

ABSTRACT: In designing the most effective choreographed aerial fireworks displays, it is useful to know when, where, and how each shell burst will appear. To do this, in addition to aesthetic features like colors, etc., three aerial shell performance parameters are needed. These parameters are: time to shell burst after firing, burst height above the ground, and burst spread. It can be difficult and expensive to generate these. However, all three can be generated using a slightly modified video camera and videocassette recorder (VCR). Further, it will generally be possible to collect the raw information during the performance of actual displays; so there is no cost for the test fireworks. This article suggests a method to gather shell performance data.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 78-82
(K4_78)

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An Instrument for the Evaluation of Black Powder as a Propellant for Aerial Shells

K. L. & B. J. Kosanke

ABSTRACT: None of the standard laboratory tests for Black Powder provide a direct indication of its performance characteristics for propelling aerial fireworks shells. Typically such testing must be performed by firing dummy projectiles on a test range—with all the problems that can entail, including the use of fairly large amounts of Black Powder for each test sample. Accordingly, a small, inexpensive laboratory test apparatus was developed, which uses only a minimal amount of powder per firing. The performance of the instrument was quantified regarding the effect of operating temperature, sensitivity of output to variations in ignition point, the effects of combustion product accumulation in the bore of the apparatus, the effect of grain size distribution, and the statistical precision of the results. Following these characterizations, the instrument was used to evaluate the performance of a series of Black Powder samples


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 4, (1995-1997), pp 63-77
(K4_63)
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Metal–Fluorocarbon Pyrolants: IX. Burn rate and Radiometric Performance of Magnesium/Teflon/Viton (MTV) Modified with Zirconium

Ernst-Christian Koch
Abstract: The burn rate, u (mm s−1) of fuel rich magnesium/Teflon/Viton (MTV) is increased by 65% upon addition of zirconium whereas the spectral efficiency Eβ (J g−1 sr−1) is reduced by 15%.
 
Keywords: Burn rate, zirconium, magnesium, MTV, polytetrafluoroethylene, radiometry, TeflonTM, VitonTM

Ref: JPyro, Issue 28, 2009, pp16-18

(J28_16) 


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