In the late 1980s, the world of U.S. Navy surface combatants is confronted with three new needs: to reduce ship signatures by factors of 10 to 1000; to provide ten‐gigawatt power pulses to new combat systems; and to reduce the high cost of hull, mechanical and electrical (HM&E) systems by taking advantage of newly‐available technology. These needs have caused an active response of the surface‐ship community to the many apparent benefits of integrated machinery systems. The acoustic signature problem accelerated interest in integrated machinery systems. A substantial reduction in noise at cruise speeds requires the elimination of propeller cavitation and requires reductions in machinery noise. The use of contrarotating tractor propellers driven by bicoupled epicyclic gears and an alternating‐current electric motor in a pod which faces directly into the flow stream is potentially capable of such performance; even better would be a contrarotating superconductive electric motor in the pod. No other concept seems even remotely competitive with these. The major reductions in installed power, fuel consumption, and reduced displacement reported in the April 1980 Naval Engineers Journal are retained. Large reductions in infrared signature and further reductions in fuel consumption are provided by intercooled recuperated gas turbines. An integrated electric propulsion system provides the opportunity to temporarily “borrow” power from the propulsion system and transform it into pulses for advanced combat systems. Not only the power of the turbines, but also the kinetic energy of the ship are available.

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A simple tumblehome hull of 4500LT lightship displacement carries 1200LT of military payload 6000NMi at 20kts with inherently‐low acoustic, infrared, and radar signatures, and with superior seakeeping, without seawater ballast. Its two intercooled, recuperated turbines replace the seven simple‐cycle engines of a comparably‐armed conventional destroyer and consume 59% less fuel; both ships share a 30kt sustained speed at 80% power. Use of stern flaps permits carrying more fuel; range is doubled to 12,000 NMi. Two removable, prealigned and pretested steerable propulsor modules are attached to the stern after construction and are pierside replaceable without drydocking; each includes a steerable pod aligned to the water inflow. Contrarotating tractor propellers are driven by a pretested integrated capsule which comprises seals, thrust bearings, contrarotating ring‐ring bicoupled epicyclic gears, and an alternating‐current electric motor. A streamlined strut connects each pod rigidly to a vertical steerable barrel which contains the individually‐replaceable propulsor auxiliaries. Two power modules are removable and are mounted in the helicopter hangar. Each module comprises a 26,400 HP intercooled regenerated gas turbine, a 3 Mw ship‐service generator, and a propulsion generator with a second high‐voltage winding for electrothermal guns.

A single-cylinder ASTM-CFR fu el-testin g e n g!n e.\~'i t h a vari able co mpression ratio ha~ been m odified to facili tate t he stud y of compression-lgmtlOn of homogen eous fuel~all' mixtures. An investi

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