Analysis of rotational forces in round bore railguns

Integrated launch packages in round bore railguns are designed to support acceleration forces based on a given current distribution in the armature/sabot. Deviation from this current distribution can lead to loads for which the launch package is not designed. One of the mechanisms which can cause current redistribution is in-bore rotation. In-bore rotation can alter the current and force distribution in a launch package leading to an early contact transition and possible launch package breakup. In a test series of the IAP/Loral SLEKE launch package at UTCEM, in-bore launch package rotation was observed. As a result, the amount of rotation was quantified, the possible causes of rotation were identified and possible solutions proposed. In this paper the authors describe the observed rotation, present the possible causes and discuss design modifications to prevent rotation.<>