Split Coil Based Design of a Coilgun

This paper presents a novel modelling approach for a coilgun operation and proposes an improved design of a reluctance type single stage coilgun. Unlike the previous works, this paper investigates the potential of coilguns as small hand-held weapons with small sized projectiles. A coilgun being electromagnetic propellant with pulsed input is quite complex to model. It involves time varying LC system, a moving projectile and magnetic field that varies with projectile motion within the coil and also affected by several other physical parameters. This paper presents a novel algorithm to model the operation of a coilgun. The proposed algorithm combines data from PSpice simulations and set of equations modelling the projectile motion under pulsed electromagnetic force. The algorithm produces projectile's trajectory for a given design and initial conditions. Moreover, an improved coil design as a split-coil is presented that improves the projectile speed and efficiency. The proposed design is used to achieve velocity of 33m/sec for a 30mm long projectile having diameter of 10mm and mass of 11.073 grams. The projectile achieves kinetic energy of 6.22J using capacitor bank of 3000uF having initial voltage of 400V and stored electrical energy of 240J. Hence the efficiency of the coilgun is 2.58% The improved split coil design is found to be 52.2% more efficient than the conventional design.