Tradeoff Studies for the Unmanned Free Swimming Submersible (UFSS) Vehicle

In the early stages of the design of the UFSS vehicle decisions had to be made between fundamentally different solutions to three basic problems: the energy source, the propulsion method, and the hull shape, which determined drag. Accordingly a series of tradeoff studies was undertaken which considered the various alternatives in the light of the desired performance levels of the vehicle and the constraints of both time and money placed on the entire effort. Possible energy sources included fuel cells, various battery systems, dynamic converters, and even a nuclear heat converter. Two different hull configurations were considered for which drag differed by a factor of three. Propulsion techniques included pump jets, a method based on the Coanda effect, and a conventional propeller coupled to a variety of prime movers. In the course of the work a great deal of quantitative information was obtained both on the technical characteristics of the various systems and on the likely costs of those which needed further development.