Characterization of M256 Bore Evacuator Performance
Abstract
Since the beginning of M256 cannon development, detailed information on the performance of the bore evacuator for different ammunition types or under various levels of degraded function has not been developed. The M256 bore evacuator is a pressure vessel which is charged with high pressure gas during firing of the cannon. As pressure inside the bore decrease, accumulated gas inside the bore evacuator is exhausted through the tube's bore evacuator holes and flows toward the muzzle end. When the metal stud case is ejected from the tube's chamber end, as the breech opens, a sympathetic flow begins which draws smoke through the bore of the cannon tube and exhausts it out the muzzle end. Proper function of the bore evacuator is directly related to its rate of discharge, its rate of leakage (if any), and the peak pressure inside the evacuator. The First Round Combustion theory is a potential explanation for the higher peak pressures experienced on the first round of firing or the first round fired after bore evacuator assembly. This suggests that the high temperature fuel-rich exhaust gases, which exist immediately after propellant ignition, combine explosively with the oxygen-rich air present inside the bore evacuator chamber. On subsequent rounds, only oxygen-depleted exhaust gases remain in the evacuator. The performance of the M256 bore evacuator is characterized by three ballistically different ammunition types. In addition, the First Round Combustion Phenomenon was explored for the first time.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1991
- Accession Number
- ADA239056
Entities
People
- David A. Porter
Organizations
- United States Army Armament Research, Development and Engineering Center