SPHERICAL SUBMERSIBLES WITH STATIC-PRESSURE HULL THRUST: AN OPTIMUM COMBINATION OF STRUCTURAL AND PROPULSION EFFICIENCIES

A preliminary theoretical and experimental study has been carried out to demonstrate the practical feasibility of spherical submersibles utilising a suction-slot boundary-layer control afterbody to achieve static pressure hull thrust. Wind tunnel tests have shown conclusively that the wake drag is reduced to a small fraction of the skin friction drag; therefore, a large static pressure thrust must occur directly on the hull. The structural efficiency of the sphere has been matched by a propulsion efficiency equal to that of a streamlined hull of equal volume and same speed. An application has been computed for a 15 ton displacement, 10 ft diameter submersible. Results show that a 50 hp motor would be sufficient for a speed of 15 knots, while a 15 hp motor would drive the submersible at 10 knots.