An investigation of electromagnetic launch repeatability

A battery-charged capacitor power system has made long-duration (6-7 s) electromagnetic launcher (EML) experiments possible. An experiment conducted to investigate EML launch-to-launch performance consistency is summarized. A series of eight ten-shot bursts each separated by 15 to 30 min was performed in one day using a single set of bore materials. EML performance repeatability was determined to vary less than 9% with respect to an average velocity calculated for the complete experiment. While there are several factors which influence the variance observed, injection velocity decay and armature initiation delays appear to be the dominant factors. The rail resistance increase that results from the bulk heating of the rails was determined to have a relatively minor influence on performance. Armature performance for the particular EML bore configuration considered was surprisingly consistent and not likely to contribute significantly to the velocity variance observed