Effect of initial temperature on the interior ballistics of a 120-mm mortar system

Heath T. Martin, J. Eric Boyer, Kenneth K. Kuo

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The effect of the initial temperature (Ti) on the interior ballistics of a 120-mm mortar system was investigated using four different experiments: temperature-conditioned closed bomb firings for determining the temperature sensitivity (σp) of the ignition cartridge's M48 double-base propellant and instrumented firings of temperature-conditioned flash tubes, ignition cartridges, and an instrumented mortar simulator (IMS). The results of these experiments reveal that for Ti ≥ 12°C, the mortar system and its sub-components exhibited regular Ti-dependent behavior, with increasing Ti causing monotonically-increasing propellant burning rates, which produce monotonically-increasing system pressures and pressure differentials in the flashtube, ignition cartridge, and IMS. However, some anomalous behavior was discovered for Ti around 46°C. Brittle fracture of the M48 propellant granules occurs at extremely low Ti. This phenomenon explains the dramatically increased variation in P-t behavior and projectile muzzle velocity at 46°C for Charge 4 firings as compared to higher Ti. Test data suggest a fundamental change in reaction kinetics occurring at extremely low Ti. This supposition is bolstered by evidence of a liquid layer existing on the surface of M48 propellant granules ejected from the ignition cartridge during Ti = 46°C firings - a phenomenon that does not occur at the higher Ti. Based on the flash tube experiments alone, the flash tube was determined to have a weak effect on the Ti-dependent behavior of the mortar system; however, IMS testing with two different flash tube configurations revealed significant differences in longitudinal pressure wave amplitude and projectile muzzle velocity in Charge 4 firings between the two configurations at -46°C, suggesting that the uniformity of combustion product discharge from the flash tube could improve the performance of the mortar at low temperatures.

Original languageEnglish (US)
Title of host publicationInterior Ballistics, Exterior Ballistics, Launch Dynamics, Vulnerability and Survivability, Explosion Mechanics
PublisherDEStech Publications Inc.
Number of pages5
ISBN (Electronic)9781605951065
StatePublished - Jan 1 2013
Event27th International Symposium on Ballistics, BALLISTICS 2013 - Freiburg, Germany
Duration: Apr 22 2013Apr 26 2013


Other27th International Symposium on Ballistics, BALLISTICS 2013

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering
  • Computational Mathematics
  • Modeling and Simulation


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