Explosive characteristics of flash powder from COBRA6 SUPER (1G) fireworks
conference paper
Explosive attacks with flash powder are frequent these days in the Netherlands. Flash powder from fireworks (often the ‘Cobra’ flash-bang) is used by criminals in ATM attacks as well as in attacks on personal properties. In order to be able to quantify the risk for the surroundings, an investigation was carried out to determine the explosive characteristics of the flash powder of Cobra6 Super (1G). Flash powder does not exhibit the same explosive behaviour as the standard high-explosives. In fact, depending on the situation, the same flash powder might deflagrate or detonate.
A component analysis and two sets of small scale experiments were carried out: (1) free-field experiments for the blast effects and (2) closed vessel tests for pressure build-up in an enclosed space. The free field experiments were carried out with hemispherical charges of 50 g of flash powder, in a plastic bag and wrapped with tape for limited confinement. The closed vessel tests were carried out for charges in the range of 0.1 to 2.0 g, inside a cylindrical vessel of 25 cm3.
To reproduce the effects of a detonating flash powder in numerical simulations, several steps were taken. The chemical equilibrium code Explo5 was used to calibrate the detonation parameters (or equation of state parameters) of the flash powder given the identified components in an estimated composition (which was not known a priori). Those parameters were then used to simulate the blast effects using the APOLLO Blastsimulator, as well as the confined pressure build-up. The composition that gave the best agreement between the simulated blast peak overpressures and the measured test data in a free field environment was selected. The selected composition together with the corresponding detonation parameters provide the foundation to investigate the blast and (semi-) confined pressure effects in different scenarios in follow-up studies.
For application in engineering blast prediction models, two values for the TNT-equivalence were determined from the test results; one for shock wave prediction from the field tests and one for quasi-static gas pressure estimates from the closed vessel tests.
A component analysis and two sets of small scale experiments were carried out: (1) free-field experiments for the blast effects and (2) closed vessel tests for pressure build-up in an enclosed space. The free field experiments were carried out with hemispherical charges of 50 g of flash powder, in a plastic bag and wrapped with tape for limited confinement. The closed vessel tests were carried out for charges in the range of 0.1 to 2.0 g, inside a cylindrical vessel of 25 cm3.
To reproduce the effects of a detonating flash powder in numerical simulations, several steps were taken. The chemical equilibrium code Explo5 was used to calibrate the detonation parameters (or equation of state parameters) of the flash powder given the identified components in an estimated composition (which was not known a priori). Those parameters were then used to simulate the blast effects using the APOLLO Blastsimulator, as well as the confined pressure build-up. The composition that gave the best agreement between the simulated blast peak overpressures and the measured test data in a free field environment was selected. The selected composition together with the corresponding detonation parameters provide the foundation to investigate the blast and (semi-) confined pressure effects in different scenarios in follow-up studies.
For application in engineering blast prediction models, two values for the TNT-equivalence were determined from the test results; one for shock wave prediction from the field tests and one for quasi-static gas pressure estimates from the closed vessel tests.
TNO Identifier
1019836
Publisher
TNO
Source title
27th International Symposium on Military Aspects of Blast and Shock MABS, ISL – French German Research Institute of Saint-Louis, Saint-Louis, France, 5-10 October 2025
Collation
13 p. + 20 sheets
Files
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