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An investigation on muzzle velocity repeatability of a railgun

The repeatability of muzzle velocity of electromagnetic railgun has been identified as a potential development issue for several years. The muzzle velocity is not only sensitive to initial parameters as charged voltage of capacitors, mass of armature, starting position, but also dynamic parameters as electric contact resistance and friction between armature and rails. This paper analyzes the effects of initial and dynamic parameters on the muzzle velocity. It is found that the most sensitive parameter is the charged voltage of capacitors. A series of 2 twenty shot bursts were performed with two sets of rails, respectively. The details of the experimental set-up and velocity measurement are described. The maximum deviation of the muzzle velocity is 3.8% with 8.47 g armatures at a mean velocity of 1913 m/s in the first twenty shot burst, and 0.92% with 10.50 g armatures at a mean velocity of 2373 m/s in the second twenty shot burst. It indicates that the repeatability of the high muzzle velocity railgun with heavier armature is better. The effects of rail current and muzzle voltage on the repeatability are discussed. The controllable key parameters affecting the repeatability of muzzle velocity are identified.