On the design of an integrated metal armature and sabot for railguns

Design requirements for a solid metal armature for a large caliber railgun are discussed, with emphasis on mechanical effects such as friction, wear and mechanical confinement. A combined friction-ohmic heating model is defined for identifying a minimum metal armature mass for a specific temperature rise due to ohmic dissipation and the total thermal loading at the armature-rail interface. Quantifying thermal loading is essential for predicting armature wear. The model was evaluated in comparisons with test data from firing of a railgun with a copper fiber brush. The tests demonstrated the effectiveness of restraining the armature in a sabot to enhance transfer of kinetic energy to the projectile and reduce rail wear.