Research on the Influence of the Arm Edge Effect on the Rotational Stability of the Spinning Projectile for the Railgun

For the stability of the spinning projectile launched by a railgun, calculation is carried out to analyze the influence of the arm edge effect (AEE). The AEE refers to that when the edge of an arm is in contact with the edge of a rail, it may produce an asymmetric electromagnetic to create an extra rotation torque. Since the current skin effect may change the magnetic field distribution when some current flow through the arm’s edge. A finite element model is established to simulate the AEE. Results show that for the projectile with separated arms, the AEE may cause the rotation torque to reverse, and the rotation torque may vary alternately between positive and negative value. When increasing the number of arms, the variation amplitude of torque is decreasing and closer to the average value. However, increasing the number of arms will also weaken its strength, so this is not a good method. Therefore, this article proposes an improved projectile, which is connecting the rear arms by a ring. This allows the current to enter the ring first and then into the arms, what may keep the rotation torque constant, and increase the strength. This article may have important guiding significance for the research of launching spinning projectile by a railgun.