January 16, 2011:  The last of four Chinese Yuan diesel-electric submarine has appeared. There was no official information released, but based on photos available it appears to be another development in China's taking Russian submarine technology and adapting it for Chinese designs. 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 (air independent propulsion system) that would allow them to cruise underwater for two weeks or more.

The Type 41A, or Yuan class, looks a lot like the Russian Kilo class. In the late 1990s, the Chinese began ordering Russian Kilo class subs, then one of the latest diesel-electric design available. Russia was selling new Kilos for about $200 million each, which is about half the price other 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 quiet 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 last two Yuans, appear to be an improvement on the first two. The first two Yuans appeared to be a copy of the early model Kilo (the model 877), while the second Yuan (referred to as a Type 41B) appeared to copy the late Kilos (model 636). The last two Yuans may end up being a further evolution, or Type 41C. The objective of all this evolution may be a sub that appears 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 two years ago. Two are under construction and eight are planned. 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 a 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. The new Chinese Yuan class boat is larger than the Kilos or Ladas, but has similar external design features. It will be a while before more details can be uncovered.

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.

Preceding the Yuans was the Type 39, or Song class. This was the first Chinese sub to have the teardrop shaped hull, and was based on the predecessor of the Kilo, the Romeo class. 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. China currently has 13 Song class, 12 Kilo class, three Yuan class and 25 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.