Minimizing Rail Deflection in an EM Railgun
ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
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Electromagnetic EM railguns have yet to be fielded due to several technical issues that need to be worked out in the near future. One of the problems is the high electromagnetic repulsive force that pushes the rails apart and causes the armature to lose contact with them. In laboratory guns, rail deflections can be minimized by building a massive containment structure. For tactical launchers, however, there is a need to keep the containment structure as light as possible, and therefore laboratory type approaches cannot be used. This paper will look at two proposed designs for use as tactical launchers. The first design has an oval shaped cross section with thick insulators and has been studied many times in the past. The second design utilizes geometric considerations and high modulus composite fibers. In this approach, the sides of the containment are kept as flat as possible so that the fibers are highly loaded in tension as the rails attempt to separate. By using ultra high modulus fibers, a thin and light weight structure can be fabricated. This paper will describe these two approaches by analyzing their best and worst case scenarios. The best case is perfect bonding between all the parts. In that case, both the insulator and the wrap contribute to holding the rail in place. The worst case is with theoretically frictionless surfaces, where the insulator does essentially nothing in minimizing the rail deflection. By comparing the best and worst case for each of these designs, a better understanding of how to minimize rail deflections using geometric considerations can be achieved.