September 3, 2012: Chinese Navy commanders appear to be satisfied with the performance of their rapidly evolving "Song" (Type 39) class diesel-electric submarines. The changes have been so great that the latest four Songs have been called Yuan class (Type 39A or Type 41).

The original design (Type 39) first appeared in 2001, and 13 have been built. But in 2008, a noticeably different Type 39 appeared. This has been called Type 39A or Type 41. Two of these Type 39As appeared before two of another variant, sometimes called Type 39B, showed up. The evolution continues and there are now six or seven "Type 41 Yuan Class" subs (of at least three distinct models). These latest models appear to have AIP (air independent propulsion system) along with new electronics and other internal improvements.

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 this latest version of what appears to be the Type 41 design shows Chinese naval engineers getting more creative. Two or more Yuans are believed to have an AIP that would allow them to cruise underwater longer. Western AIP systems allow subs to stay under water for two weeks or more. But the Chinese AIP has less power and reliability and does not appear to be nearly as capable as Russian or Western models. But the Chinese will keep improving on their AIP, just as they have done with so much other military technology.

The Songs look a lot like the Russian Kilo class and that was apparently no accident. The 39s and 41s are both 1,800 ton boats with crews of 60 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. Russia was selling new Kilos for about $200 million each, which was about half the price Western nations sold similar boats for. The Kilos weigh 2,300 tons (surface displacement), have six torpedo tubes, and a crew of 57. They are quiet and can travel about 700 kilometers under water at a speed of about five kilometers an hour. Kilos carry 18 torpedoes or SS-N-27 anti-ship missiles (with a range of 300 kilometers and launched underwater from the torpedo tubes). The combination of quietness and cruise missiles makes Kilo very dangerous to American carriers. North Korea and Iran have also bought Kilos.

The first two Type 41s appeared to be a copy of the early model Kilo (the model 877), while the second pair of Type 41s 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 first Lada underwent three years of sea trials before they were declared fit for service three years ago. Since then more problems have developed and for a while the Lada was considered cancelled. That has changed and construction of two more is supposed to resume this year. The Chinese better be careful what they steal from Lada. China appears unconcerned with the Lada woes and seems content to perfect their version of the Kilo and put dozens of them into the water. If they can do that, it will be quite an accomplishment.

The Kilo class boats entered service in the early 1980s. Russia only bought 24 of them but exported over 30. It was considered a successful design. But just before the Cold War ended in 1991, the Soviet Navy began work on the Lada. This project was stalled during most of the 1990s, by a lack of money but was revived in the last decade.

The Ladas have six 533mm torpedo tubes, with 18 torpedoes and/or missiles carried. The Lada has a surface displacement of 1,750 tons, are 71 meters (220 feet) long, and carry a crew of 38. Each crewmember 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 the sub can travel as much as 10,000 kilometers using its diesel engine (underwater, via the snorkel). Submerged, using battery power, 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 (air independent propulsion) system. Russia was long a pioneer in AIP design but in the last decade, Western European nations have taken the lead. Construction on the first Lada began in 1997, but money shortages delayed work for years. The first Lada boat was finally completed in 2005. A less complex version, called the Amur, is being offered for export, but so far there have been no sales.

The Ladas are designed to be fast attack and scouting boats. They are intended for anti-surface and anti-submarine operations as well as naval 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. This quietness is what the Chinese are looking for because diesel-electric boats are the quietest available (all things being equal), even quieter than AIP. If nothing else, Lada provides a possible further development path for the Chinese Song/Yuan boats.

The Type 39s were the first Chinese subs to have the teardrop shaped hull. The Type 41 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.

China currently has 13 Song class, 12 Kilo class, seven Yuan class and 25 Ming (improved Russian Romeo) class boats. There are only three Han class SSNs, as the Chinese are still having a lot of problems with nuclear power in subs. Despite that, the Hans are going to sea, even though they are noisy and easily detected by Western sensors. Five Hans were built (between 1974 and 1991) but two have already been retired. The Song/Yuan class subs are meant to replace the elderly Mings.