An application of a parameter fitting model to the University of Tennessee Space Institute transaugmented railgun

Part of the difficulty in explaining the disparity between theoretical and experimental performance in railguns has been a result of a difficulty in identifying a number of pertinent parameters. The purpose of this paper is to attempt to identify the values of several parameters in a model of the forces involved for two types of electromagnetic launchers. A parameter identification method was applied to each shot using a numerical scheme to solve a force model for each type of launcher and to solve the associated differential equations obtained from differentiating the model force differential equation with respect to the desired parameters. The following constant parameters were sought:

L' ~ self inductance per unit length of rail

M' — mutual inductance per unit length of rail

a’ -- an ablation coefficient

C_f ~ an armature viscous drag coefficient , and

u₀ – the initial velocity The results of the runs for each shot was averaged and statistically compared. The averages were compared to previous attempts to identify these parameters, and a statistical assessment of the reliability of the method was made.