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The Greater Underwater Propulsion Power Program (GUPPY) was initiated by the United States Navy after World War II to improve the submerged speed, maneuverability, and endurance of its submarines. (The "Y" in the acronym was added for pronounceability.) The navy began the program by testing and reverse engineering two captured German Type XXI U-boats: ''U-2513'' and ''U-3008''. That analysis led to four goals—increasing the submarines' battery capacity, streamlining the boats' structures, adding snorkels, and improving fire control systems. The navy immediately focused on designing a new class of submarines, but the Bureau of Ships believed the fleet of existing ''Gato'', ''Balao'', and ''Tench'' class submarines could be modified to incorporate the desired improvements. In June 1946, the Chief of Naval Operations approved the GUPPY project. The initial two-boat test program, implemented by the Portsmouth Naval Shipyard, eventually grew into several successive conversion programs. Those upgrades proceeded in seven variants, in the following order: GUPPY I, GUPPY II, GUPPY IA, Fleet Snorkel, GUPPY IIA, GUPPY IB, and GUPPY III. Some boats that went through an early phase were then upgraded further in a later phase. A similar programme for the Royal Navy involved modifications to 24 wartime and post-war British T- and A-class submarines, which were provided with streamlined hulls, sail-type conning towers, and increased underwater performance during 1948-60. == GUPPY I program == The prototype GUPPYs, and (both Portsmouth-built ''Tench'' boats), appeared in 1947. Externally, they featured improved streamlining of the bridge and shears structures, and periscope and radar mast supports. To reduce hydrodynamic drag, one of the periscopes was deleted. No snorkel was fitted, due to difficulties in adapting the snorkel to the fleet boat. Deck guns and their associated containers were removed. An SV radar aerial was added to the top of the sail, creating a distinctive side bulge. All capstans, cleats, and rail stanchion supports were redesigned so they could be retracted or removed when rigged for dive. Most notably, the sharp V-shaped "fleet boat bow" was replaced with a distinctive rounded "Guppy bow" that improved submerged performance.〔Friedman, pp. 40-41〕 These modifications changed not only the boats' appearance, but also their terminology: After a GUPPY conversion, the faired structure around the boat's conning tower and mast supports was called the "sail". Internally, the boats underwent considerable rearrangement to accommodate larger battery wells and batteries of greatly increased electrical power. The batteries were of a new design. Compared with the original Sargo battery, the Guppy battery used a greater number of thinner plates that would generate higher current for a longer time. However, these batteries had a shorter life, 18 months versus the five years of the Sargo battery, and took longer to charge. They also required ventilation to remove hydrogen gas, and required cooling water to the battery terminals and termination bars. Four 126-cell batteries were installed in enlarged battery wells that replaced former storage, ammunition, and refrigeration spaces. These four batteries could be connected in series or parallel, providing a wide range of voltages and currents, and thus a wide range of speeds.〔Friedman, pp. 25, 41〕 In the maneuvering room, two or four of the earlier high-speed motors and reduction gears were replaced by slow-speed motors. All open-front switchboards were replaced with enclosed splash-proof cabinets. Lighting and other "hotel" electrical loads were converted to use 120 volt 60 hertz alternating current, and ship electronics to use 120 volt 400 hertz AC. A new air conditioning system of greatly increased capacity was also installed. In service, these boats offered greatly improved underwater performance. ''Pomodon'' reached 17.8 knots surfaced and submerged as compared to the previous performance of 20.25 knots surfaced and submerged, ''Odax'' slightly less.〔Friedman, p. 40〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Greater Underwater Propulsion Power Program」の詳細全文を読む スポンサード リンク
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