Abstract
The paper describes the enhancement of an existing gun dynamics simulation package, to introduce spin to the flexible shot model. The original one or two piece flexible shot model was based on finite element beam theory, and therefore spin needed to take into account the moments of inertia at each node. Each node is therefore treated as an independently spinning body, each with its own spinning axes which can be related to the next node so that stiffness forces between them can be calculated. The stiffness coefficients are recalculated as deformation takes place, which is particularly important with long rod penetrators because of the high accelerations involved which induce buckling moments in the rod as it bends. The relationship between the nodes and the stiffness coefficients is maintained by updating the direction cosines for each node, plus a set for the overall beam.The final model has been validated against known rigid model cases, by increasing stiffness until flexing is reduced. Comparisons have then been made with standard whirling cases.