Modern submarines (like the Seawolf and Virgina classes) are often propelled not by propellers, but by pumpjets. These are shrouded turbines with a number of blades, looking much like the inlets and compressors of modern high bypass turbofans. They provide propulsive improvement, but apparently more importantly they are quieter than exposed propellers. However, the details of their designs are often obscure, for the obvious fact that they make submarines stealthier vehicles.
One of the few pumpjets I’ve seen shown in any detail comes from a 1963 General Dynamics report covering unusual propulsion system options for submarines. At this early date it’s safe to assume that the resemblance to a modern pumpjet is probably fairly minimal beyond the overall concept and configuration, but it’s still an interesting look at a rarely seen technology Additionally, the pumpjet is about the *least* unconventional of the concepts shown in detail, which include props that are fitted to a ring at the maximum diameter of the hull and separate, podded propulsion systems (a common enough design feature on many surface vessels today) and cycloidal propulsion systems. All of the systems are compared by assuming they are applied to SSB(N)-616 USS Lafayette, a ballistic missile sub.
DESIGN STUDY REPORT: A SURVEY OF CONVENTIONAL AND UNCONVENTIONAL SUBMARINE PROPULSION SYSTEMS
This report can be downloaded from the Defense Technical Information Center website.
The link to the abstract is here.
The direct link to the PDF file is here.
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