Ultra-stiff, low mass, electromagnetic gun design

High performance in an electromagnetic (EM) gun implies high velocity with minimal transition from a solid to plasma armature. Factors that affect gun performance include armature integrity, bore straightness, and bore stiffness. Experiences firing solid. armature at the Center for Electromechanics at The University of Texas at Austin since 1987 have shown that the lack of one or more of these three ingredients will result in less than desirable performance. This paper presents a simple, ultra-stiff and low mass EM gun design that provides five to six times the rail-to-rail structural stiffness than a conventional bolted, composite sidewall-type EM gun construction. This translates into minimal bore deflection which lessens the amount the armature must distort to maintain a low voltage contact with the rails. The EM gun design incorporates a passive preloading mechanism that maintains a compressive stress state in the bore components without the use of hydraulics. Bore preload is provided that exceeds the maximum rail-to-rail EM loads and is reacted by 4 composite structure that also provides longitudinal barrel stiffness. Manufacturing techniques are presented that would allow the design to be built on a small or large scale using standard manufacturing tolerances and demonstrated assembly processes. Material selection and impact on the ability to actively cool a railgun is also presented.