Abstract: A shot test was examined for evaluating the ignitability of cylindrical bare and primed stars. The primed stars were more easily ignited than the bare stars. The ignition limit lift charge was defined and used for evaluating the ignitability. Though the ignition limit lift charges of the primed stars were widely scattered, the order of average ignitability of primed stars was: F > J > D > C > L > G > A > E > H > K > I > B The order of ignitability of bare stars was: blue star > yellow star > purple star > green star > red star. The hot plate and electric match tests were carried out for screening the ignitability of star, prime, lifting charge and bursting charge compositions. Both the test methods may be applied to screen the ignitability of bare star compositions from the other more ignitable compositions though there are rare exceptions.

Keywords: fireworks, ignitability, shot test, hot plate test, electric match test, prime, star, lifting charge, bursting charge

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Abstract:The spectroscopic measurement of sparklers, torches and senko hanabi (Japanese sparklers) was carried out. The three dimensional spectra of sparklers and torches showed that the peak intensities of the spectra fluctuate with time. In the burning of sparklers, white, titanium, senko and iron sparklers showed mainly the K peak suggesting that the incandescent emission is principally in the visible light area. The white and titanium sparklers showed high K peak intensities compared to other sparklers suggesting the high temperature burning of Al and Ti. Among the tested sparklers the excitation purities of titanium and blue sparklers were relatively low. Regarding torches, the flame, sparks and falls were compared. The K peak intensity of falls was largest compared to other kinds of torches, presumably because the falls contain the energetic aluminum. The purity of the blue torch was exceptionally small. The spectra and photographs of burning sparklers and torches were compared. The fireball and the branching sparks of senko hanabi were recorded using the profiles of K peak intensity of the senko hanabi at two burning locations.

Keywords: toy fireworks, spectroscopic measurement, emission spectra, torch, sparkler, glitter, senko hanabi

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Abstract: Burning experiments were carried out for stars and lifting charge in the air and in a closed vessel. Three types of stars were used, that is, ordinary spherical, half-restricted spherical and hemispherical surface-restricted stars were used as models for flying burning. Partly restricted stars gave longer burning times than the ordinary stars, but not enough to explain the flying burning behavior. This was attributed to the burning of the ignition promoter in the restricted stars.

The ratio of the time to maximum pressure to the stationary burning time of stars was about 0.44 and that of the lifting charge was about 0.24, presumably because the burning rate of the stars is smaller than that of the lifting charge.

Keywords: firework stars, lifting charge, burning time, stationary burning, flying burning

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Abstract: Burning and shot experiments have been carried out to examine the burning time and the trajectory of burning firework stars. The burning time in flight was longer than the stationary burning time. The trajectory of a burning star in the air was modeled assuming the linear burning rate of the star and CD = at + b. It was found that there are sometimes abnormal trajectories and interruption of the burning during flight for a large star with high initial velocity.

Keywords: Exterior ballistics, firework star, burning rate, initial velocity

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Abstract: Recoil from fireworks articles often arises as a concern in accident investigations or when fireworks are launched from unconventional locations such as rooftops, or other light building elements such as overhangs, from decks of small bridges or those of barges. In this latter case, the Authority Having Jurisdiction will typically require some assurance that the structure will not be damaged and is sufficiently robust to support the dynamic loads resulting from the function of the firework articles. In this study, it is proposed that such measurements can also be used to evaluate multi-shot devices since; their recoil load history reflects their performance in time and magnitude.

Various researchers have, over the last decade, devised means to measured recoil loads. Piezoelectric load cells, which have fast response time, have been used and found to satisfactorily track the fireworks recoil loads. This study presents data obtained using an apparatus in the form of a 25-cm diameter platform. Fireworks mortars or articles are placed and functioned on the platform. The signal from the piezoelectric load cell is recorded by a digital storage oscilloscope.

The results indicate that the recoil history can be used to determine inter-shot times, total duration, and relative launch heights of the effects of the multi-shot article. In addition, defective launches and other modes of failure such as in timing can also be easily identified.

Keywords: multi-shot fireworks, recoil, load cell, RLP, mortar

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• Survey of Firework Trends from UK Display Companies by Tom Smith and Avril diPalma
• Thermal Conductivity Testing of Minimal Volumes of Energetic Powders by Adam Harris and Daniel N. Sorensen
• Review by Theodore S. Sumrall of: Introduction to Fireworks by T Yoshida and D Ding
• Review by Megan Bottegal and Bruce McCord of: Pyrotechnic Chemistry by Journal of Pyrotechnics
• Review by Bernard E. Douda of: Bombs and Bombings, A Handbook to Protection, Security, Detection, Disposal, and Investigation for Industry, Police, and Fire Departments by Thomas G. Brodie