Projectile Dispersion of a Marker Ball Launcher

Report No. ARL-TR-3319
Authors: Peter J. Fazio
Date/Pages: October 2004; 30 pages
Abstract: The Weapons Technology Analysis Branch of the Ballistics and Weapons Concepts Division, Weapons and Materials Research Directorate of the U.S. Army Research Laboratory conducted a test of the firing ability of a marker ball launcher mounted on a robotic research laboratory vehicle. The robotic vehicle was used as a technology demonstration platform for autonomous and semi-autonomous behaviors. Some of the behaviors included the ability to return fire against enemy targets. In the interest of safety and simplicity, it was decided that a marker ball launcher would be used as the robot?s ?weapon? system. A fully integrated marker ball launcher and turret assembly, the return fire simulator (RFS), was mounted on the robotic vehicle. The RFS mounts a 0.68-inch caliber, 16-inch-long launcher barrel onto a Directed Perceptions pan-and-tilt assembly. Some of the autonomous robotic behaviors require the robotic vehicle to fire a specified number of rounds to achieve a 90% probability of hit (pHit). To meet this requirement, an estimate of the launcher round dispersion, based on the range to the target, was needed. A test was developed to determine an estimate of the number of rounds required to achieve a 50%, 75%, 90%, 95%, and 99% pHit against a target of a specified cross-sectional size at various ranges. The test ranges were 20, 40, 60, and 80 feet from the muzzle of the launcher to the target board. At each range, 20 rounds were fired and their impact points were recorded. For each round fired, the optical aim point, produced by a class II laser, was recorded. The data were collected and analyzed to generate the azimuth (x coordinate) error and elevation (y coordinate) error and the total (x and y coordinate) error. The statistical means and standard deviations of these errors and of the muzzle velocities were calculated. The means of the azimuth error and elevation error were used to calculate the azimuth and elevation angular offsets, respectively. These data and the target crosssectional size were used to calculate the number of shots required to achieve the probabilities of hit at the four target ranges.
Distribution: Approved for public release
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Last Update / Reviewed: October 1, 2004