Editing Soviet submarine K-222 (section)

==Background==
The Soviets were well aware of the drawbacks of the large [[SS-N-3 Shaddock]] family of missiles, notably its need to be launched from the surface and its complicated target-acquisition process, both of which rendered the submarines launching the missiles vulnerable to the carriers that they were intended to attack.<ref>Hampshire, p. 11</ref> The [[Council of Ministers of the Soviet Union|Council of Ministers]] issued a resolution on 28 August 1958 calling for a very ambitious submarine development program that called for a doubling of speed, a 50 percent increase in diving depth, smaller nuclear reactors and steam turbines, and a long-range missile system of small dimensions able to be fired while submerged, and new materials, among other objectives. Design bureau [[Malakhit Marine Engineering Bureau|TsKB-16]] began development of Project 661, an experimental cruise-missile submarine, later that year in response to the resolution. Chief designer N. N. Isanin decided to begin a clean-slate design that would use existing technology as little as possible. By July 1959 a sketch design was ready for a submarine capable of {{convert|38|kn|lk=in}} and the State Committee for Shipbuilding had to make decisions about what the submarine's [[hull (watercraft)|hull]] would be constructed of and what type of [[nuclear reactor]] would be used.<ref>Polmar & Moore, pp. 136–137</ref>

[[Aluminium]] was quickly rejected as unsuitable because of its poor resistance to corrosion and poor performance under high pressure at high speeds. While new alloys of steel were still under development,<ref>Vilches Alarcón, p. 45</ref> titanium had some major advantages. It was much stronger than steel for a given weight, resisted corrosion better and was non-magnetic. This would help protect it against [[magnetic mine]]s and registering on [[magnetic anomaly detector]]s of [[anti-submarine warfare|anti-submarine aircraft]]. Disregarding the extremely high cost of titanium compared to steel and that titanium could not be welded in an oxygen atmosphere, the committee selected it. Two types of reactor were potentially available at this time, [[Pressurized water reactor|pressurized water]] or [[lead-bismuth eutectic]]. The Soviets had some experience with the former, but none with the latter; this proved to be the deciding factor as the committee was unwilling to wait for the lead-bismuth reactor to be developed even though it promised to be smaller for the same amount of power output.<ref name=p7>Polmar & Moore, p. 137</ref> ''K-222'' would be the first submarine built with a titanium hull.<ref name=p9/>

These decisions produced a design that had an underwater speed of 38 knots and was capable of carrying 10–12 missile launchers forward of the [[Sail (submarine)|sail]], but was larger than the specified [[Displacement (ship)|displacement]] if fitted with two [[propeller shaft (ship)|propeller shaft]]s. The committee considered using a single shaft, but ultimately rejected it, preferring the redundancy of two reactors. It did delete the auxiliary [[diesel generator]] that earlier nuclear-powered submarines had been equipped with to compensate for using two shafts when it accepted the sketch design and authorized preliminary design work in February 1960. The final design was approved three months later.<ref name=p7/> To reduce the technical risk of many of the advanced components chosen, the navy modified five existing submarines to test various systems such as the [[P-70 Ametist|P-70 ''Ametist'' (NATO reporting name: SS-N-7 Starbright)]], [[GRAU]] designation: 4K66; {{langx|ru|П-70 «Аметист»}} '[[Amethyst]]') missiles, [[sonar]]s and other electronics.<ref name=p7/><ref name=p6>Vilches Alarcón, p. 46</ref>