Electromechanical aspects of reliable loading procedures for multishot railguns

A railgun represents a system whose behaviour is strongly influenced by electromechanical interactions. For instance, the breech voltage depends on electrical parameters such as the current and its time derivative as well as on mechanical parameters like the velocity and the position of the projectile. Hence, disturbances of mechanical origin can have severe implications on the electrical circuitry. Such an interaction resulted in the destruction of diodes within the pulse forming network of the medium calibre multishot railgun RAFIRA when the third projectile was launched. The first two projectiles (masses of 140 grams each) left the railgun at a velocity of about 750 m/s without problems. A detailed investigation linked the fault to the loading process of the third projectile which did not reach its designated position in the main launcher. The thorough analysis allowed us to work out a solution which resulted in the modification of mechanical parts involved in the projectile loading process. Several successful loading tests confirmed the mechanical changes made.