Effect of railgun electrodynamics on projectile launch dynamics

A series of experiments were conducted for examining the disturbances actin g upon a subprojectile during electromagnetic launch. This investigation us es a number of performance indicators, including target impact dispersion, to quantify the causes. The effects of armature contact configuration and i n-bore acceleration profile on the launch process were considered. The test program consisted of two armature contact configurations and two i n-bore accelerations. Twenty-eight shots were fired, of which 15 were slugs . For the test matrix, the nominal exit velocity was 1,100m/s. The in-bore acceleration profile was varied by diverting the armature current with a ti me delayed closing switch, located at the muzzle of the railgun. Effects fr om the launch disturbances were quantified by use of flash x-rays, smear ca mera photography, and yaw card and target impacts. The time-rate-of-change of launcher and switch currents and launcher voltages were measured. Result s indicate significant differences in ballistic performance for the two fro nt contact configurations. Also, to a lesser extent, differences were obser ved for the two in-bore acceleration profiles. In-bore dynamics initiated f rom the deviation from the bore centerline are believed to cause these diff erences.