X-ray investigation of dynamic phenomena occurring during combustion of the pyrotechnic charges of 40 mm grenade fuze delay systems

Abstract

Experimental Real Time X-ray Radioscopy (RTR) investigation of dynamic phenomena occurring during the combustion of end-burning pyrotechnic charges confined in the fuze body, utilized in the delay systems of 40 mm grenade fuzes, are presented. These pyrotechnic delay systems delay the arming distance pyromechanism and the self-destroying timing assembly. The charge in the delay arming distance pyromechanism was a black powder pellet supported by the safety pin kept in constant position by its driving compressed spring. The self-destroying timing assembly comprised three pyrotechnic segmented columns connected at their ends with ignition relay channels, creating a zig-zag firing train. The following dynamic phenomena were detected and registered by RTR at a frequency of 30 FPS: (i) combustion zone travelling along the pyrotechnic charges, (ii) displacements of the pyromechanism safety pin caused by either the pressure of its spring after burning out of the black powder pellet or by pressure of the combustion products escaping from the zig-zag firing train, (iii) transfer of the ignition impulse between the adjacent pyrotechnic columns, (iv) pressure action of the combustion products on the pyrotechnic columns during transfer of the ignition impulse, and (v) transfer of the final output ignition impulse from the last (third) pyrotechnic column through the channel leading directly to the chamber used for accommodating the fuze detonator.