Debunked: Chinese Navy stretched KILO Class submarine
Flag A video capture posted on Chinese media on 9th September 2018 appeared to show a Chinese Navy stretched Pr. 877EKM KILO Class submarine. The boat is shown with a hull insert approximately 15 meters long. The increased space most likely accommodated an Air Independent Power (AIP) system to increase the submarine’s stealth in littoral environments.

China Stretched KILO class submarine - Covert shores

China received two Pr. 877EKM Class submarines in 1994-5, followed by two Pr. 636 KILO Class boats in 1997-8 and 8 Pr.636M KILOs in 2004-6. The modified submarine is thought to be one of the first two Pr.887ECM boats and is based in China’s South Sea Fleet.

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China already operates AIP submarines with at least thirteen Type 039A Yuan Class boats in service. Chinese AIP systems are reported to be of the Stirling type, similar in concept to those found n Swedish and Japanese submarines.
China Stretched KILO class submarine - Covert shores

Although adding an AIP insert into a KILO is within China's capabilities, images have since emerged in the Chinese official publication Naval & Merchant Ships, Dec 2018 which cast serious doubt on the existance of the stretched KILO:
China Stretched KILO class submarine - Covert shores

The image appears credible at first glance and the official publication is often treated as a reliable source. The AIP system in the lower righthand illustration is a Stirling Engine and the large cylindrical object beneath it is the liquid oxygen storage tank. This is consistent with representations of the indigenous Chinese AIP system on Type-039A/B submarines.

The image comes with the caveat that it is based on Open Sources, and a closer examination of the AIP hull insert raises serious doubts:

  1. The specified length of 88 meters doesn't match with what we know about AIP inserts:

    • A Project 877EKM KILO has an overall length of 72.6 meters. A 15.4 meter insert is much bigger than any other AIP back fit that seen.
    • When the Russians talked about inserting an AIP module in Project 877/636 Kilos, the initial size estimates were 9-10 meters.
    • The Swedish Västergötland submarines that received the Stirling engine had a 12 meter insert, but these boats have a far smaller pressure hull diameter than the KILO. The original trials submarine, Näckan, only required an 8-meter insert.
  2. You can see nine frames in lower right graphic inside the hull:

    • This is wrong as the KILO is a double-hull boat so the frames should be on the outside of the pressure hull.
    • Even if the diagram were correct, the KILO class has 600mm between frames which means the drawn insert is on the order of 6 meters long, not the 15.4 meters claimed.
  3. The stretched KILO has not been verified in commercial satellite imagery. While not guaranteed so soon, this is surprising if a boat had been modified and deployed to a major submarine base. Chinese KILOs are based on Hainan and their base is regularly covered with in Open Source satellite imagery.

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Since September, there have been several posts about this submarine in some of the discussion groups where it was claimed that the submarine is a CGI rendering used in TV documentary/movie and that it is not real. A photo surfaced which unwittingly provides damning evidence:
China Stretched KILO class submarine - Covert shores
It shows new fixed hydroplanes on the sail (marked A) (aka 'Fairwater planes'). The KILO's retractable hydrplanes (B) are not removed however!

Case closed: FAKE.

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