In a number of single-shot applications and experiments at remote locations where flux-compression generators provide the most practicable power source, it may be necessary to use cascaded generators with inductive coupling between them to provide the required power amplification. The complexity of the resulting system appears to have so far inhibited the development of any simple but complete numerical code, and has prevented a full understanding of the complex action of the overall system. The present paper meets these requirements, by extending an existing simple 2D helical generator code, and shows how this can be used to solve problems arising from the design stage of a prototype system.