A multiple armature railgun launcher

As longer projectiles are accelerated, the efficiency (projectile mass/launch mass) of the launch package decreases. The reduction in efficiency makes launching projectiles with a L/D (length-to-diameter ratio) greater than 20 undesirable. EM guns have several launch characteristics that differ from conventional guns. Higher launch velocities are achievable in EM guns because sonic gas velocities do not limit the projectile velocity. Acceleration profiles for EM guns are more constant. The acceleration forces can be distributed on the projectile easily because the accelerating force can be distributed with multiple armatures. These characteristics combine to make EN guns a very attractive approach for launching very long (i.e.. high L/D ratio) projectiles. Railgun launchers with multiple armatures can distribute the accelerating force. Each armature is supplied gun current for acceleration through its own set of rails. This multi-rail, multi-armature concept was tested at the railgun test facility. The results demonstrated feasibility. We were able to control current distribution to multiple armatures. This paper describes the theory and test results for multi-armature launch of high L/D projectiles.