K-222 was the first and only Project 661 (NATO reporting name: Papa class) nuclear-powered cruise-missile submarine built for the Soviet Navy during the Cold War. Although the Soviets saw K-222 as an unsuccessful design, upon completion it was the world's fastest submarine and the first to be built with a titanium hull.
The submarine was given several names over the course of its construction and service: she was originally designated K-18, named K-162 while under construction, and renamed to K-222 in 1978.
Dissatisfied with the Echo class of nuclear submarines, which had to surface to fire their missiles, in 1958 the Soviet government authorized an exceedingly ambitious program for a very fast boat equipped with missiles that could be launched while submerged. It accepted the preliminary design two years later and construction began in 1963; work proceeded very slowly as techniques for working titanium had to be developed and quality control was inconsistent. The program's objectives were generally satisfied, but the government had failed to include a requirement to minimize the submarine's acoustic signature which meant that K-222 was easily detectable at high speed. The Soviet Navy rejected a plan to place the design into series production as its flaws outweighed its advantages, but it pioneered the technology needed to work with titanium on a large scale, which enabled the subsequent construction of more successful designs using titanium.
Commissioned in 1969, the-then K-162 was armed with 10 short-range, anti-ship cruise missiles and four torpedo tubes to carry out her mission of destroying American aircraft carriers. These missiles could be fitted with either conventional or nuclear warheads. The submarine served in the Soviet Red Banner Northern Fleet through the 1970s, but the discovery of hull cracks led to a lengthy repair period from 1972 to 1975. After an accident with K-222's nuclear reactor in 1980, the submarine went on her final operational patrol in 1981. She was removed from service in 1988 and scrapped in 2010.
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. The 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 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 and the State Committee for Shipbuilding had to make decisions about what the submarine's hull would be constructed of and what type of nuclear reactor would be used.
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, 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 mines and registering on magnetic anomaly detectors of 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 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. K-222 would be the first submarine built with a titanium hull.