Projectiles With Rod-Shaped Payloads for the PEGASUS Railgun

The PEGASUS railgun facility at the French-German Research Institute is equipped with a 6-m launcher with a caliber of 40 mmtimes40 mm. An electric energy with a maximum value of 10 MJ can be supplied by a high-power capacitive storage. The current is injected at 13 locations distributed along the barrel. Projectiles or launch packages in the mass range of 1 to 4 kg were designed in order to obtain both a good electrical and mechanical performance and tested with the PEGASUS facility. The sabot consists of a metal fiber brush armature embedded in an insulating low-density structure made of a glass/epoxy composite material. In the mass range of about 0.3 kg these sabots equipped with eight metal-fiber brushes (without payload) are able to achieve muzzle velocities up to 2200 m/s without any damage to the glass/epoxy structure due to the acceleration process. The tungsten alloy rods used as payload were placed in front of the sabot, i.e., they were screwed or bonded into the composite structure. A structural analysis of the sabot containing the tungsten rod was performed with the mechanical dynamic FE-Code LSDYNA3D. The calculated three-dimensional stress state inside the sabot composite structure shows that the critical stresses are essentially located in the interface region of the bore for the rod. Solutions are proposed to reduce the high stresses and transferred to the projectile design. Experimental observations using flash radiographs taken at the muzzle of the railgun show that the payload rods can be launched correctly