Tang-class submarine

Probably the most important innovation of the Tangs, and their primary advantage over contemporary GUPPY conversions, was an increase in test depth from {{convert|400|ft|m|abbr=on}} to {{convert|700|ft|m|abbr=on}}, achieved with the same High Tensile Steel (HTS; {{convert|42000|psi|MPa|abbr=on}} yield strength) as the Balao and Tench classes. This allowed the class to take advantage of deeper ocean conditions to evade sonar, as well as maneuver more safely at moderate depths.{{cite book

| last = Friedman

| first = Norman

| authorlink =

| title = Submarine Design and Development

| publisher = United States Naval Institute

| year = 1984

| location = Annapolis, Maryland

| pages = 61

| url =

| doi =

| isbn = 0-87021-954-5 }}

An unsuccessful innovation of the Tang design was the General Motors EMD 16-338 lightweight, compact, high-speed "pancake" engine, rated at 1,000 bhp. Very different from the classic diesel engines that nearly all preceding submarines used, which were laid out with a horizontal crankshaft, this new engine had a vertical crankshaft, and the cylinders were arranged radially like an aircraft engine. Four of these {{convert|13+1/2|ft|m|adj=mid|-tall}}, {{convert|4|ft|m|adj=mid|-wide}}, eight-ton engines could be installed in a single engine room, thus deleting an entire compartment from the submarine's design. The goal was to reduce overall length, as testing had shown that shorter submarines were more maneuverable, especially in depth, and had less submerged drag. Four compact Guppy-type 126-cell lead–acid batteries were installed to provide a high sustained submerged speed. The overall design allowed for a {{convert|25|kn|km/h|abbr=on}} top speed and possible future propulsion replacement with a Type XVII U-boat-derived hydrogen peroxide turbine, closed-cycle diesel system, or even a nuclear power plant. However, attempts to develop the first two systems were unsuccessful, and nuclear power plants proved too large to be accommodated in the Tang-class hull.Friedman since 1945, pp. 46–48Gardiner and Chumbley, p. 603

When the boats went to sea in the early 1950s, the new engines did not work well. Their compact, high-speed design made them difficult to maintain, and they tended to leak oil into their generators. In 1956, the Navy decided to replace the pancake engines with three ten-cylinder Fairbanks-Morse opposed-piston 38D 8-1/8 diesels. These were similar to those of late-war World War II boats, but uprated from {{convert|1350|shp|abbr=on}} to {{convert|1600|shp|abbr=on}} each. To accommodate the larger engines, the boats had to be lengthened some nine feet in the engine room (three additional frames between frames 69 and 70). Accordingly, in 1957 and 1958, the first four Tangs were lengthened, while Gudgeon and Harder, still on the ways, were built to the new length with the new engines. This propulsion plant was used for almost all subsequent US conventional submarines.

The torpedo tubes were also redesigned. The six forward tubes now used air-powered piston ejection pumps, which forced a slug of water through a slide valve behind the torpedo to push it out, rather than the pulse of air used in previous designs. Because this design is somewhat quieter and does not release an air bubble every time a torpedo is fired, it has been used in all subsequent submarine designs throughout the world. The four stern tubes of previous classes were reduced to two shorter, simpler tubes that could not accommodate the longer anti-ship torpedoes and had no capability to actively eject torpedoes. Rather, they were designed for the Mark 27 and planned Mark 37 swim-out torpedoes.

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In October 1946, the first two boats were ordered. {{USS|Tang|SS-563|2}} was built at Portsmouth Naval Shipyard; {{USS|Trigger|SS-564|2}} at the Electric Boat yard in Groton, Connecticut. In 1947, contracts were awarded to Portsmouth for {{USS|Wahoo|SS-565|2}} and to Electric Boat for {{USS|Trout|SS-566|2}}. Then in 1948, a similar pair of contracts were awarded to Portsmouth for {{USS|Gudgeon|SS-567|2}} and to Electric Boat for {{USS|Harder|SS-568|2}}. They are named for six US submarines lost during World War II, of which most of their commanding officers were killed in action while combating Japanese surface vessels.

In 1967, Tang, Wahoo, Gudgeon, and Harder received an additional 15-foot ({{convert|15|ft|disp=output only}}) section (five additional frames between frames 42 and 43) to accommodate the BQG-4 Passive Underwater Fire Control Feasibility System (PUFFS) passive ranging sonar installation, with three tall domes added topside, and additional fire control equipment that enabled the use of the Mark 45 nuclear torpedo. This left the boats similar in size and capability to the GUPPY III conversions.Friedman since 1945, pp. 28, 43

Two boats of this class, TCG Pirireis (ex-Tang) and TCG Hizirreis (ex-Gudgeon), are preserved as museum ships in Turkey. Pirireis is at the İnciraltı Sea Museum in İzmir, and Hizirreis is at the Kocaeli Museum Ships Command in Izmit.[http://www.denizmuzeleri.tsk.tr/en/tgmk/default.asp Kocaeli Museum Ships Command] {{Webarchive|url=https://web.archive.org/web/20141222081103/http://www.denizmuzeleri.tsk.tr/en/tgmk/default.asp |date=2014-12-22 }}

{{Commons category|Tang class submarines}}

{{Reflist}}

• Blackman, Raymond V.B. Jane's Fighting Ships 1971–72. London: Sampson Low, Marston & Co., 1971. {{ISBN|0-354-00096-9}}.
• Gardiner, Robert and Chumbley, Stephen, Conway's All the World's Fighting Ships 1947–1995, London: Conway Maritime Press, 1995. {{ISBN|1-55750-132-7}}.
• [http://www.navsource.net/archives/08/08idx.htm NavSource Postwar Diesel Submarines photo gallery index]
• {{DANFS}}

{{Tang class submarine}}

{{US submarine classes after 1945}}

Category:Submarine classes

Tang

Tang

Category:Radial diesel engines