Skipjack-class submarine
The "Skipjack" class was a class of United States Navy nuclear submarines (SSNs) that entered service in 1959-61. This class was named after its lead boat, . The new class introduced the teardrop hull and the S5W reactor to U.S. nuclear submarines. The "Skipjack"s were the fastest U.S. nuclear submarines until the s, the first of which entered service in 1974. Design. The "Skipjack"s' design (project SCB 154) was based on the USS "Albacore"'s high-speed hull design. The hull and innovative internal arrangement were similar to the diesel-powered "Barbel" class that were built concurrently . The design of the "Skipjack"s was very different from the s that preceded the "Skipjack"s. Unlike the "Skate"s, this new design was maximized for underwater speed by fully streamlining the hull like a blimp. This required a single screw aft of the rudders and stern planes. Adoption of a single screw was a matter of considerable debate and analysis within the Navy, as two shafts offered redundancy and improved maneuverability. The so-called "body-of-revolution hull" reduced her surface sea-keeping, but was essential for underwater performance. Also like "Albacore", the "Skipjack"s used HY-80 high-strength steel, with a  yield strength of , although this was not initially used to increase the diving depth relative to other US submarines. HY-80 remained the standard submarine steel through the "Los Angeles" class. Another "Barbel"-like innovation was the combination of the conning tower, control room, and attack center in one space. This was continued in all subsequent US nuclear submarines. Combining the functions in one space was facilitated by the adoption of "push-button" ballast control, another feature of "Albacore". Previous designs had routed the trim system piping through the control room, where the valves were manually operated. The "push-button" system used  hydraulic operators on each valve, remotely electrically operated (actually via toggle switches) from the control room. This greatly conserved control room space and reduced the time required to conduct trim operations. The overall layout made coordination of the weapons and ship control systems easier during combat operations. Much of the overall internal arrangement was continued in the subsequent "Thresher"- and "Sturgeon"-class submarines. The "Skipjack"s' five compartments were called the Torpedo Room, Operations Compartment, Reactor Compartment, Auxiliary Machinery Space (AMS), and Engine Room. With the addition of a missile compartment, the arrangement of the first 41 US nuclear-powered ballistic missile  submarines (SSBNs) was similar. The design was primarily single-hull, with a double hull around the torpedo room and AMS for ballast tanks. The design was improved on the "Thresher"s, the one-off , and subsequent attack submarines by relocating the torpedo room into the operations compartment via angled midships torpedo tubes to make room for a large sonar sphere in the bow. The "George Washington" class, the first SSBNs, were derived from the "Skipjack"s, with rebuilt from the incomplete first . The hull of "Scorpion" was laid down twice, as the original hull was redesigned to become the "George Washington". Also , the material for building was diverted into building , which delayed "Scamp"s progress. The bow planes were moved to the massive sail to cut down on flow-induced noise near the bow sonar arrays. They were known as sail planes (fairwater planes). The "Skipjack"s were the first class built with sail planes; they were later backfitted on the "Barbel"s. This design feature would be repeated on all U.S. nuclear submarines until the improved , the first of which was launched in 1988. The small "turtleback" behind the sail was the exhaust piping of the auxiliary diesel generator. The "Skipjack"s also introduced the  S5W reactor to U.S. nuclear submarines. It was known as ASFR (Advanced Submarine Fleet Reactor) during development. The S5W was used on 98 U.S. nuclear submarines of 8 classes and the first British nuclear submarine, , making it the most-used US Navy reactor design to date. The design of the prototype HMS Dreadnought is closely related to the Skipjack class. The entire aft section of HMS Dreadnought was identical to the Skipjack class as the hull was built around the reactor and could not be changed but the fore section was based on earlier British studies into nuclear submarine design , great care had to be taken to marry the two designs alignment. Service. "Skipjack" was authorized in the FY 1956 new construction program and commissioned in April 1959. Each hull cost around $40 million. "Skipjack" was certified as the "world's fastest submarine" after initial sea trials in March 1959, although the actual speed attained was classified. The "Skipjack"s remained the fastest US nuclear-powered submarines until the first of the "Los Angeles" class entered service in 1974. This was due to the increased size of the "Thresher" and "Sturgeon" classes, which retained "Skipjack"s S5W power plant, plus the  introduction of the "skewback" screw, which was quiet but mechanically inefficient. The "Skipjack"s saw service during the Vietnam War and most of the Cold War. The "Skipjack"-class submarines were withdrawn from service in the late 1980s and early 1990s except for , which sank on 22 May 1968 southwest of the Azores while returning from a Mediterranean deployment, with all 99 crewmembers lost. Ships in class. The gap in the hull-number sequence was taken by the two one-of-a-kind submarines and .