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Defence & Arms Last Updated: Mar 19, 2019 - 2:23:12 PM

Submarines: Russia Got The AIP Blues
By Strategy Page, March 18, 2019
Mar 18, 2019 - 1:01:35 PM

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In early 2019 Russia confirmed that the second Lada class submarine would be completed and ready for sea trials by the end of 2019. The first Lada had entered service in 2010 but the second two were cancelled in 2011 when the navy revealed that years of sea trials (Lada had been completed in 2005) demonstrated that the performance of this design did not meet navy requirements and work was halted on the second and third ones. But the second Lada was nearly ready for launch and the work already completed was preserved. Thus it was possible to resume work quickly and the second Lada was launched in September 2018. The third Lada had work resumed in 2015 but that was halted before it was ready for launch.

The main problem with Lada appears to have been the long promised Russian AIP (air independent propulsion) system. That AIP, and several other upgrades later added to new Kilo class models were supposed to justify calling the Ladas a new class of sub, not just another improved Kilo. Russia then turned to an Italian ship builder to jointly develop and build the Amur class subs, which would use Western AIP tech. Russia was never able to obtain any export sales of Amur and the project was canceled in 2013. Amur would have been dead soon anyway because of the sanctions imposed on Russia because of the2014 invasion of Ukraine.

Lada was developed in the 1990s, as the successor to the Kilo class, but the promised differences that made Lada unique, especially the AIP, were never ready so there was not enough difference between the Lada and the improved Kilos being built to justify continuing work on the Kilo successor. The Lada has a surface displacement of 1,750 tons, are 71 meters (220 feet) long, and carries a crew of 38. Each crew member has their own cabin (very small for the junior crew, but still, a big morale boost). When submerged the submarine can cruise at a top speed of about 39 kilometers an hour (half that on the surface) and can dive to about 250 meters (800 feet). The Lada can stay at sea for as long as 50 days and can travel as much as 10,000 kilometers using its diesel engine (underwater, via the snorkel). Submerged, using battery power alone, the Lada can travel about 450 kilometers. There is also an electronic periscope (which goes to the surface via a cable) that includes a night vision capability and a laser range finder. The Lada was designed to accept an AIP system.

The Ladas are designed to be fast attack and scouting boats and have six 533mm torpedo tubes, with 18 torpedoes and/or missiles carried. They are intended for anti-surface and anti-submarine operations as well as reconnaissance. These boats are said to be eight times quieter than the Kilos. This was accomplished by using anechoic (sound absorbing) tile coatings on the exterior and a very quiet (skewed) propeller. All interior machinery was designed with silence in mind. The sensors include active and passive sonars, including towed passive sonar. Russian submarine designers apparently believe they can install most of these quieting features into improved Kilos, along with many other Lada features. But the main distinction between Lada and late-model Kilos is the AIP and the second Lada does not have it. The plan is to see if the accumulated Kilo upgrades applied to the Lada work and then install the AIP in the third Lada.

What Russia has not discussed is the fact that most Kilos, and Ladas as well, are meant for export and China has been getting more and more export sales that otherwise would have been for Russian Kilos. China has been building its own Kilo clones and in mid-2018 the Chinese navy proclaimed that its new AIP equipped submarine had performed very well. Actually, as described the Chinese AIP performed about as well as early Western AIP systems. For the Chinese that was good enough because they have had problems getting their AIP (apparently based on the Swedish Stirling AIP system) to perform adequately and reliably. China has been working on getting a working AIP system in one of their Yuan class Type 39B subs for over fifteen years but until now no Chinese AIP equipped boats were seen in action. That changed in early 2018 when a new Yuan class sub went to sea and operated like an AIP boat (staying underwater for more than seven days at a time). According to the Chinese press releases their AIP sub stayed under for over two weeks at a time, which is typical of what a Stirling AIP system can do.

China may now have three of these AIP equipped boats. That is because in late 2016 China apparently resumed building more of its Yuan class subs. These are based on the late model Russian Kilo class diesel-electric boats. Construction of the Yuans appeared have halted in 2013 for reasons unknown. Then at the end of 2016 three more of these Yuan class (Type 39B) subs were seen being built. The last new Type 39B appeared in late 2013 but even before that, there were indications that this was another pause to absorb user experience with the current model and plan modifications for the next batch. This new batch is apparently the three new ones that recently went to sea. When these enter service China will have ten Type 39Bs, plus three of the earlier Type 39A versions.

In late 2016 it was believed the three latest 39Bs would have many modifications and upgrades, some of them visible because of minor changes in the conning tower or hull features. China was apparently upgrading its sensor and fire control electronics but the capabilities of these won’t be detected until foreign subs encounter the new 39Bs at sea. At that point, U.S. subs will be able to construct an acoustic and electronic “signature” of the new 39Bs so they can be more easily and quickly identified in the future. That process also confirmed that the latest 39Bs had working AIP. How reliable the AIP is will come only after thousands of hours of use but so far the Chinese AIP appears to have encountered no major problems.

One thing was certain about the latest Type 39Bs; the Chinese are continuing their relentless effort to create world-class subs, one tweak and improvement at a time. Since the late 1980s, China has been designing and building a rapidly evolving collection of "Song" (Type 39) class diesel-electric submarines that emphasize quietness and incremental improvements. The changes have been so great that the four Songs completed in 2013 were recognized as a new type and designated the Yuan class (Type 39A). The original design (Type 39) was a 1,800 ton Kilo type sub that first appeared in the late 1990s and 13 were built. The larger (2,800 ton) Type 39A first appeared in 2006. The Type 39A quickly involved into the larger and more lavishly equipped Type 39B showed up. The evolution continues, and there are now thirteen "Type 39 Yuan Class" subs (of at least four distinct models). These latest models were thought to have AIP along with new electronics and other internal improvements. Now the presence of AIP has been confirmed.

This rapid evolution of the Type 39 appears to be another example of China adapting Russian submarine technology to Chinese design ideas and new technology. China has been doing this for as long as it has been building subs (since the 1960s). But the recent versions of the Type 39B design shows Chinese naval engineers getting more creative. The Yuans were meant to have an AIP that would allow them to cruise underwater longer. Western AIP systems allow subs to stay underwater for two weeks or more. China has been working on AIP since 1975 and the first working prototype was available by 1998. A decade later it seemed that design was ready for regular use but it wasn’t. The first Chinese AIP had less power and reliability and did not appear to be nearly as capable as planned Russian or existing Western models. In part, this was because that AIP used lead-acid batteries. The Chinese kept improving on their AIP, and the last half dozen AIP systems were designed to use a more efficient lithium battery system. This AIP 2.0 has numerous other tweaks and appears, on paper at least, to match what most Western AIPs can do and that’s the version that was installed in one (or all three) of the latest Type 39B subs.

The Songs look a lot like the Russian Kilo class and that was apparently no accident. The 39s and 39A/Bs are both similar in appearance but the type 39A/Bs appear larger than the 1,800 ton Type 39s. Both have with crews of 60-70 sailors and six torpedo tubes. This is very similar to the Kilos (which are a bit larger). China began ordering Russian Kilo class subs, then one of the latest diesel-electric designs available, in the late 1990s. The first two Type 39Bs appeared to be a copy of the early model Kilo (the model 877), while the second pair of Type 39Bs appeared to copy the late Kilos (model 636). The latest Yuans still appear like Kilos but may be part of an evolution into a sub that is similar to the Russian successor to the Kilo, the Lada. The Type 39s were the first Chinese subs to have the teardrop shaped hull. The Type 39B was thought to be just an improved Song but on closer examination, especially by the Russians, it looked like a clone of the Kilos. The Russians now believe that the entire Song/Yuan project is part of a long-range plan to successfully copy the Kilo. If that is the case, it appears to be succeeding and the Russians suddenly rushing to resume work on an AIP Lada seems to confirm that. Other evidence is the AIP equipped Chinese subs being offered to export customers.

Meanwhile China has been offering their “improved Kilo” designs to export customers. In late 2016 China confirmed that final details have been agreed to on the sale of eight Chinese S20 diesel-electric submarines to Pakistan. These are export versions of the Type 39A that lack many of the advanced features. Four of these will be built in China while at the same time Chinese personnel will assist Pakistan in building another four in Pakistan. Final cost is expected to average somewhere between $500 million and $600 million each and the first one will enter service by 2023. Since early 2014 China and Pakistan have been negotiating prices and terms for the sale of the S20. At first, it was believed that Pakistan wanted six subs, but the final deal specified eight. Currently, the Pakistani Navy has five submarines and plans to use all of them against India (which is also considered a Chinese foe). In 2017 China sold three of those export model Yuan class subs to Thailand. These boats will cost over $400 million each. Five years earlier those nations would have been inclined to select the veteran Kilo that first entered service in 1982. So far, 70 Kilos have been built, 60 are still in service and more are under construction. It may be an old design, but it is mature and has been updated with modern electronics and quieting technology. But Kilo never had AIP and Russia has yet to demonstrate that their AIP design actually works.

Source:Ocnus.net 2019

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