Archive for February 2007

Erratum for JPyro, 7, 1998, p2

The Production of Music with Pyrotechnic Whistles

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Erratum for JPyro, 5, 1997, p3

Model Rocket Engines, Theory and Design

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Erratum for JPyro, 4, 1996, p29

Progress in Developing a Fuel-Air Salute

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Erratum for JPyro, 3, 1996, p39

Ammonium Perchlorate Composite Basics

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Erratum for JPyro, 2, 1995, p19

Introductory Chemistry for Pyrotechnists, Part 2: The Effects of Electrons”

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Erratum for JPyro, 1, 1995, p14

An Introduction to PROPEP, A Propellant Evaluation Program for Personal Computers

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Pyrotechnic Whistles

W. R. Maxwell

Introduction: The fact that certain pyrotechnic compositions when pressed into a tube and ignited burn with a loud whistling noise has been known and used by firework manufacturers for many years. The two compositions most widely employed appear to be (a) a mixture of dry powdered potassium picrate and potassium nitrate in the proportions of about 60/40 and (b) a mixture of powdered gallic acid and potassium chlorate in the proportions 25/75. Whistling compositions have occasionally been used for military purposes. Thus in World War II the Germans had a whistling cartridge (pfeif-patrone) for signaling and the Canadians used a whistling thunderflash for training purposes. In October, 1943, the author was instructed to investigate in collaboration with the Admiralty the use of pyrotechnic whistles burning under water as a possible counter measure to the acoustic homing torpedo then being used by the Germans. As little was known about the factors influencing the intensity and frequency of the sound made by pyrotechnic whistles or their mode of action an investigation into this subject was made and is described in the present paper. A number of measurements were also made on pyrotechnic whistles burning under water, but as they are mainly of acoustical interest only, they will be dealt with very briefly.


Ref: JPyro, Issue 4, 1996, pp37-46
(J4_37)
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Progress in Developing a Fuel-Air Salute

Fred Ryan

ABSTRACT: In a fuel-air salute a fine metallic fuel is first dispersed into the surrounding air, then ignited. Such a salute is much safer than a conventional salute as the salute fuel must be mixed with air to obtain the oxygen needed to function. It can not explode violently in bulk or in a mortar tube because the salute contains only fuel. Even if fired while lying on the ground, its explosive power is reduced. This preliminary paper summarizes progress achieved to date in fuel-air salute construction and suggests areas for future study.

Keywords: fireworks, salutes, fuel-air, safety, dust explosions


Ref: JPyro, Issue 4, 1996, pp25-36
(J4_25)
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Evaluation of Fire and Explosion Hazards for a Non-Azide Gas Generant

Kazuo Hara, Mitsuhiro Kanazawa, and Tadao Yoshida

ABSTRACT: A hazard evaluation has been carried out for the safety assessment of a new non-azide gas generant for automotive airbag inflators. The gas generant (UN) is composed of urazole (U) and a metal nitrate (MNO3;N) with other additives included to provide the required performance. The impact, shock, friction, electric spark, hot object and heat sensitivities were determined by the appropriate tests.  Propagations of detonation, deflagration and combustion were examined using the United Nations gap test and VP 30 tube test. A mixture of urazole with KClO4 in a stoichiometric ratio propagated detonation as measured by the gap test and self-sustaining combustion as measured by the tube test. The mixture of urazole with KNO3 propagated combustion, but no detonation.

Keywords: airbag, gas generant, urazole, hazard evaluation, test methods


Ref: JPyro, Issue 4, 1996, pp15-24
(J4_15)
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Flash Powder Output Testing: Weak Confinement

K. L. and 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: JPyro, Issue 4, 1996, pp5-15
(J4_5)
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