Compacted Modified Propellant Blocks as Traveling Charge in the Hybrid Shot Scheme

Abstract

The burning of compacted modified propellant charges applied as a traveling charge in the hybrid shot scheme was studied. The block charges were manufactured by pressing fine propellant grains coated by a thin film of polyvinyl butyral. A stick from several pressed pellets was insulated over its lateral surface by a thin layer of silicon paste, glued to the back of the projectile and inserted into the barrel of the 23‐mm smooth‐bore laboratory gun. The loose‐packed accelerator charge was placed in the breech. Combustion was initiated by an igniter plug placed between the traveling and breech charges. A set of piezo‐quartz gauges placed in the breech and along the barrel, as well as a frame‐target device were used for recording characteristics of the firings. It is shown that blocks of this type, applied as the traveling charge, provide a stable burning process resulting in high ballistic performance. The block traveling charge preserves its integrity in the course of its motion along the barrel, and burning envelopes its total mass when pressure in the breach passes the maximum value. The descending portion of the pressure diagram demonstrates appreciable transformation, with convex or secondary hump sections. The shape of spatial pressure profiles behind the moving projectile is also transformed, and the pressure at the projectile butt end may be higher than the pressure in the breech. Compared to the conventional charges at the same maximum pressures the muzzle velocity increment attains 340 m s−1 (or 23 %) for a light 35‐g projectile and 200 m s−1 (or 19 %) for a heavy 104‐g projectile.

Towards Safer Primers: A Review

“…Some of these parameters are listed in Table 1 and have been derived from various test methods. The Trauzl lead-block test measures the deformation induced by 10 g of explosive in a standardised lead block as a means to compare performance [139,140] High speed camera photography is used frequently to image burn and propagation rate, size of emitted particles or ionised gas, and ignition delay (also measured by oscilloscope) [56,141]. Figure 13 shows snap shots of a typical plasma formation sequence after application of a 420 V bias to a metallic bridge.…”

Research on the Needle Deformation of Extrusion Mold for 19-hole Propellant

“…Scholars at home and abroad have studied the properties of propellants for decades and achieved remarkable results. Khomenko Yu P [1]，Ermolaev B S [2][3][4] researched on using porous ring-cut rod propellant charging technology to improve the loading density, the maximum filling density reaches more than 1.1g/cm 3 , and the filling density can be increased by more than 10% compared with the granular propellant charge. Through the selection of binders, plasticizers and combustion modifiers for lowsusceptibility emissions, as well as the design and theoretical calculation of formulas and theoretical calculations, Liao Xin [5,6] basically determined the formulation of the low vulnerability propellant composed of RDX as energy-containing fillers, inert energetic composite binder, composite plasticizer, combustion modifier and mechanical property improvers.…”

Effect of ignition delay runaway of traveling charge on gun firing safety

“…The test results showed that the projectile muzzle velocity could be increased by 2.8% and 4.2% respectively under the maximum chamber pressure of 330MPa and 400MPa with the traveling charge scheme covered by flame retardants. In 2014, Ermolaev B S et al [16] made an traveling charge by bonding and compacting fine propellant grains and covering them with polyvinyl butyral diaphragm, which was glued to the bottom of the projectile by silicone rubber, and carried out an experimental study using a 23 mm smoothbore ballistic gun, which showed that the use of this compacted block as an traveling charge provided a stable combustion process, which resulted in an increase in the projectile muzzle velocity by about 20%. In 2015, Michaels D et al [17] from Israel studied a propulsion system based on combustion chamber jet traveling charge and established an interior ballistic model, which was compared and verified with the test results.…”