Watervliet, NY: US Army Armament Research, Development And Engineering Center
Erosion modeling predictions are given for the current M829E3 round configuration and weighted averages per temperature for the computer correction factor (CCF). Our gun erosion model was developed through a ten-year joint partnership with Software and Engineering Associates, Inc., Carson City, NV. These predictions are based on recent cannon characterization data. These latest predictions include significant changes in propellant configuration and projectile weight that were made to the current M829E3 configuration compared to our initially presented M829E3 modeling predictions two years ago. For the last two years, additional nonablative M829E3 erosion modeling predictions have not been conducted or presented. This was due to a diversion of erosion modeling resources toward ablative M829E3 erosion predictions and erosion predictions related to the selection of six M256 cannons for M829E3-related fatigue testing. For the current M829E3 configuration, these changes in gas pressure, gas temperature, gas velocity, and increased projectile weight collectively contributed to a predicted increase in M256 cannon erosion life compared to our initially presented M829E3 modeling effort. In addition, the current set of M829E3 weighted averages per temperature for CCF from Fort Knox (19% hot 49°C/120°F, 64% basic 21°C/70°F, 16% cold -7°C/20°F, and 1% severe -32°C/-25°F) collectively contributed to a further predicted increase in M256 cannon erosion life compared to the two-year-old set of weighted averages per temperature (33% hot, 33% basic, 0% cold, and 33% severe). For the current predictions, the peak eroded cannon axial position remains at approximately 60 inches from the rear face of the tube ±6 inches; and this position dictates the erosion life of the cannon. Erosion life predictions at this position are given for each of the round-conditioning temperatures and the Fort Knox mixture of round-conditioning temperatures. At this peak eroded position, the respective 49°C/120°F, 21°C/70°F, -7°C/20°F, -32°C/-25°F, and Fort Knox mixture round-conditioning temperature cases have predicted erosion lives of approximately 183, 287, 388, 302, and 269 rounds. The mixture of M829E3 rounds with some types of HEAT and slug rounds significantly moves the peak eroded axial position up-bore to the bore onset region.
