Preceded by Tench class | Built 1949–1952 | |
Builders Portsmouth Naval ShipyardElectric Boat Company Succeeded by USS Nautilus (SSN-571)USS Seawolf (SSN-575)Skate class | ||
The Tang-class submarines were an American class of submarines developed from the Greater Underwater Propulsion Power Program (GUPPY) conversion program for World War II submarines, which incorporated German Type XXI U-boat technology into the United States Navy's submarine design. They comprised the state of the art in post-World War II conventionally powered submarine design; some of their features were incorporated into the nuclear-powered submarines that replaced them in the 1950s and beyond.
Contents
Design
Probably the most important innovation of the Tangs, and their primary advantage over contemporary GUPPY conversions, was an increase in test depth from 400 ft (120 m) to 700 ft (210 m), achieved with HY-42 (42,000 psi (290 MPa) yield strength) steel. The improved HY-75 steel would not appear until mid 1950s. This allowed the class to take advantage of deeper ocean conditions to evade sonar, as well as maneuver more safely at moderate depths.
An unsuccessful innovation of the Tang design was the General Motors EMD 16-338 lightweight, compact, high-speed "pancake" engine. 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. Three of these 13 1⁄2-foot-tall (4.1 m), 4-foot-wide (1.2 m), 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. Four compact Guppy-type 126-cell lead–acid batteries were installed to provide a high sustained submerged speed. The overall design allowed for a 25 kn (46 km/h) 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.
When the boats went to sea in the early 1950s, the new engines did not work well. Their compact 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 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 1,350 shp (1,010 kW) to 1,600 shp (1,200 kW) each. To accommodate the larger engines, the boats had to be lengthened some nine feet in the engine room, and even then, only three could be installed. 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.
Ships in class
In October 1946, the first two boats were ordered. Tang was built at Portsmouth Naval Shipyard; Trigger at the Electric Boat yard in Groton, Connecticut. In 1947, contracts were awarded to Portsmouth for Wahoo and to Electric Boat for Trout. Then in 1948, a similar pair of contracts were awarded for Gudgeon and Harder. 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- or 18-foot (4.6 or 5.5 m) section to accommodate the BQG-4 Passive Underwater Fire Control Feasibility Study (PUFFS) passive sonar installation, with three tall domes added topside. The extension accommodated additional fire control equipment that enabled the use of the Mark 45 nuclear torpedo. This left the boats very similar in size and capability to the GUPPY III conversions.
Museum ships
Two boats of this class, TCG Pirireis (ex-Tang) and TCG Hizirreis (ex-Gudgeon), are preserved as museum ships in Turkey. Ex-Tang is at the İnciraltı Sea Museum, in İzmir, and ex-Gudgeon is at the Kocaeli Museum Ships Command in Izmit.