A Methodology for Characterizing Barrel Flexure Due to Tank Motion

Abstract : Barrel centerline curvature is known to influence the location of projectile shot impacts. Superimposed on the unique manufactured barrel centerline is the flexed barrel shape that can occur prior to firing while the tank is on the move. In order to understand and quantify the effects of barrel flexure on gun accuracy, it is necessary to determine what combination of fundamental mode shapes is most likely to occur. A method to accomplish this task is described in this report. The method is demonstrated by enumerating the 10 most likely mode shape combinations (flexed barrel shapes) that were found to occur in an M256 barrel mounted in an MlA2 tank while it traversed the RkC-9 bump course at Aberdeen Proving Ground, MD, at 15 mph.