Friction and ablation measurements in a round bore railgun

Detailed experiments were performed in order to determine electrode ablation and friction effects in a round-bore railgun. An accelerating model was developed which includes electrode-ablation effects, the viscous arc drag, and the mechanical friction of the projectile. In addition, a novel nonlinear electrode-ablation model was found to describe the experimental data very well. A model for the mechanical friction force between the projectile and bore wall was applied to the equation of motion. The position/time data of the projectile acceleration could be adjusted with quite reasonable friction effects. Theoretical and experimental results show that the 'ideal' projectile velocity is decreased by about 28%: 15% due to electrode ablation, 9% due to mechanical friction, and about 4% due to viscous arc drag. >