Submarines: Noise From Russia

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June 16, 2016: Despite all the boasting and bluster coming from Russia, there’s less and less available to back it up. For example in late 2015 Russia revealed that it would modernize twelve Oscar II and Akula class Cold War era nuclear subs in order to extend their service lives twenty years. This was necessary because there was neither time nor money available to replace these twelve subs with newly built ones. The older boats will be equipped with similar weapons and electronics as are in the new Yasen class subs. The modernized boats will also have needed and often long delayed) repairs made. What won’t be changed much is the amount of noise these boats make while submerged. The noise is a fatal vulnerability for subs.

The U.S. has found that, given current sensor (sonar, magnetic, heat, chemical) technology it is possible to detect very quiet submerged diesel-electric sub. This includes the new ones one using AIP (Air-Independent Propulsion) systems that allow diesel-electric sub to stay under water, silently, for several weeks at a time. Since 2000 the United States has done a lot of work on improving systems used to detect submerged subs. This included lots of tests on diesel electric and AIP subs that led to many small tweaks to existing sensors on subs and surface ships. AIP boats, in particular, were found to have many vulnerabilities. The AIP technology generated more noise and heat than just using batteries for underwater propulsion. The more the U.S. studied AIP subs in operation the more ways they found these subs could be detected. The passive (listen only) sonar systems in the new Virginia class SSNs (nuclear attack sub) were tweaked considerably to better find diesel-electric and AIP boats. The sensors on the Virginia are also among the best (if not the best) available for finding surface ships or other nuclear subs. But it depended on how noisy the other ships were. Diesel-electric subs operating submerged using battery power are theoretically the quietest. But the older a sub gets the more components become noisy and some diesel-electric sub designs are simply quieter. Even the older and noisier diesel-electric subs tend to be quieter than most nuclear subs, which have to run pumps at all times to circulate cooler water around the hot nuclear reactors. The most recent nuclear sub designs have found more ways to conceal the pump noise along with noise in general. Add that to more effective noise detecting sonar and you have a Western edge that Russia was getting close to matching when the Soviet Union collapsed in 1991. Before 1991 the Russians had managed to steal a lot of the silencing tech and smuggle in special manufacturing equipment to create the quieter components. But all that ended in the 1990s and all the Russians had left were less than a dozen “quiet” nuclear subs that had been completed by 1991. After that Western, especially American, silencing and sensor tech continued to improve, although not as fast as during the Cold War.

Russia considers the Yasen their answer to the American Virginia class. But the Virginias are a more recent design while the Yasen is a late Cold War effort that had some tech upgrades in the two decades it took to build the first one. The first Virginia began construction in 1999 and entered service in 2004. So far twelve are in service, five are under construction and a total of 48 are to eventually enter service. The 9,500 ton Yasen were built after the Cold War but from Cold War era designs and are armed with 32 P-800 (SS-N-26 Oniks) anti-ship missiles fired from eight VLS (vertical launch system) silos. The three ton P-800 has a range of 600 kilometers. Each of these silos can hold five Klub anti-ship or cruise missiles instead of four P-900s. There are also ten torpedo tubes (8 650mm and two 533mm). The P-900s are designed as "carrier killers." The torpedo tubes were originally supposed to be all the new and larger 650mm types so that new torpedo designs could be used. All those new designs did not work out as planned so two standard 533mm torpedo tubes were installed to use older but proven torpedo designs.

The Yasen are highly automated, which is why there is a crew of 90 that is a third less than the 134 needed to run the new U.S. Virginia class boats. The Yasen is based on the earlier Akula and Alfa class SSNs. Russia had originally planned to build 30 Yasens, but now seven or eight seems a more realistic goal. Because of this Russia has gone ahead with a program for refurbishing Cold War era boats just to obtain a respectable number of subs in the future. What Russia has not been able to do is keep up with silencing and detection (sensor) tech. American sub commanders are not being overconfident about all this but base their assessments on growing opportunities for the quieter American SSNs (especially the Virginias) to detect and Russian SSN (or diesel-electric boat) and stalk it for days or weeks without ever being discovered. This was a Cold War practice as well and how the U.S. Navy discovered, in the 1980s, that the latest Russian SSNs were much quieter. But there are few of them and now improved American sensors make them easier to detect.

While only one Yasen has been to sea (another will soon do so and four more are under construction) the U.S. apparently was able to detect and stalk it, getting a good sense of how much quieter (apparently not enough) it is. As improved as Yasen is it had lots of problems getting into service. For example it took two decades of construction effort and nearly six months of acceptance trials before the Russian Navy could finally put the first Yasen (Graney) SSGNs (nuclear powered cruise missile sub) into service during mid-2014. This boat, the Severodvinsk, set some of the wrong kind of records on its way to join the fleet. For one thing construction of the Severodvinsk began in 1993. Then there were the sea trials, which took two years during which the Severodvinsk was at sea 30 percent of the time (222 days) and submerged over a hundred times. There were at least five live firings of its cruise missiles. Sea trials are not supposed to go on for that long, but these SSGNs were special in so many ways.

Russian submarine building has been on life support since the Cold War ended in 1991. Many subs under construction at the end of the Cold War were cancelled, and the few that avoided that spent a decade or more waiting for enough money to resume construction. The first Yasen crew was put together in 2007 and then spent years training, and waiting. The crew now has their new boat in service, but only after record delays and time spent in the shipyard getting tweaked.

 


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