Abstract
Electromagnetic railguns are able to launch projectiles at velocities beyond 2500 m/s. The French-German Research Institute of Saint-Louis ISL has been operating railguns of various sizes for more than 25 years, ranging from small caliber (10-mm) guns to the 6-m long NGL60 launcher with a 60 mm square caliber. In this work, the launch and sabot discard process of projectiles is investigated, using ISL’s 3-m long railgun of caliber 25 mm. Two different types of projectiles are examined. The first type has a cylindrical geometry with a conical nose. By choosing different lengths, the projectile mass ranges from 15 to 60 grams. A thread allows for the transfer of the acceleration load from the armature-sabot petals to the cylinder. The muzzle velocities of this test series are located between 1300 m/s and 2100 m/s. The second type is a coneshaped projectile, made of copper alloy, with a base diameter of 20 mm and a round nose. Velocities up to about 1600 m/s were achieved with this type. Relevant insight in the mechanisms limiting the muzzle velocity could be obtained, which proves beneficial for future launcher up-scaling. The particular feature of the launch package design for both types of projectiles is the common separation of armature and sabot. Symmetrical discard makes sure that their craters of impact do not interfere with the projectile impact in the center region of the target plate.
