Portsmouth Naval Shipyard|
Electric Boat Company
|Operators:||United States Navy|
|Preceded by:||Tench-class submarine|
USS Nautilus (SSN-571)|
USS Seawolf (SSN-575)
1,560–2,050 long tons (1,585–2,083 t) surfaced|
2,260–2,700 long tons (2,296–2,743 t) submerged
|Length:||268 ft (82 m), extended to 287 ft (87 m), then to 302 ft (92 m)|
|Beam:||27 ft (8.2 m)|
|Draft:||17 ft (5.2 m)|
|Propulsion:||twin shafts, electric motor, GM 16-338 "pancake" engines, replaced by Fairbanks 38D8-1/8 opposed piston engines|
15.5 knots (17.8 mph; 28.7 km/h) surfaced|
18.3 knots (21.1 mph; 33.9 km/h) submerged
|Range:||10,000 nmi (19,000 km) at 10 kn (12 mph; 19 km/h) on snorkel|
|Endurance:||1 hour at 17.5 kn (32.4 km/h) on battery|
|Test depth:||700 ft (210 m)|
|Complement:||8 officers, 75 men|
|Armament:||8 × 21 in (533 mm) torpedo tubes (6 forward, 2 aft)|
The Tang class submarines were a product of the Greater Underwater Propulsion Power Program (GUPPY), which incorporated German 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; a design that was incorporated into and replaced by the nuclear-powered submarines of the 1950s and beyond.
One of the first innovations incorporated into the Tangs was the General Motors 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 and two banks of eight cylinders each, this new engine had a vertical crankshaft, and the cylinders were arranged radially like an aircraft engine. Four of these 13½-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 torpedo tubes were also redesigned. The six forward tubes now used a slug of water 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 Mk 27 and planned Mk 37 swim-out weapons.
In addition, Tangs would use the HY42 (42,000 lb (19 t) yield stress) steel. (The new HY75 would not appear until the middle 1950s.) Her design planned for 25 kn (46 km/h; 29 mph) speed and closed cycle propulsion (as would the contemporary Porpoise and Narval classes.
In October 1946, the first two boats were ordered. USS Tang (SS-563) was built at Portsmouth Naval Shipyard; USS Trigger (SS-564) at the Electric Boat yard in Groton, Connecticut. In 1947, contracts were awarded to Portsmouth for USS Wahoo (SS-565) and to Electric Boat for USS Trout (SS-566). Then in 1948, a similar pair of contracts were awarded for USS Gudgeon (SS-567) and USS Harder (SS-568). Their names were based on six US submarines lost during the war, of which most of their commanding officers were killed in action while combatting Japanese surface vessels: Gudgeon, Wahoo, Trout, Trigger, Harder and Tang.
Construction and delivery followed without significant difficulty, but 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 diesels. 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.
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