How China Builds Stealth Submarines in a SECRET River Shipyard

How does China build silent submarines that run without air, on a river hundreds of miles from the sea? This engineering documentary goes inside the Type 039C, the newest known member of China's Yuan-class family of AIP (air-independent propulsion) attack submarines, and the secret riverside shipyard in Wuhan where they are built. We follow the full build process, from steel hull sections to sea trials. Wuchang Shipyard, part of China State Shipbuilding Corporation (CSSC), moved to a vast new base at Shuangliu on the Yangtze River with 2,800 meters of shoreline. There, submarines are assembled inside covered construction halls, rolled out on rails, launched sideways into the river and towed toward the coast. You'll learn how a diesel-electric submarine can stay underwater far longer using a Stirling engine that burns diesel with stored liquid oxygen, why its exhaust can be dissolved into seawater without a noisy compressor, and how China's 711 Research Institute spent decades developing the technology. We also break down submarine quieting: the Type 039C's stealth-shaped sail, skewed propellers, and the "floating raft" machinery mounts that isolate engine vibration from the hull. Then comes the real-world test. Pakistan ordered eight Hangor-class submarines, a Yuan-family export design based on the S26, with four built in Wuhan and four at Karachi Shipyard under technology transfer. Both the Pakistan deal and Thailand's S26T submarine were delayed for years when Germany blocked export of the MTU 396 diesel engine, forcing China to switch to its own CHD620. The lead boat, PNS Hangor, was commissioned in April 2026 and fired its first missile in the North Arabian Sea in September 2026. In this video: A Submarine Built Far From the Sea Inside the Wuchang Shipyard on the Yangtze The Photo That Revealed the Type 039C How a Diesel Submarine Runs Without Air How Stirling AIP Works Decades of Engine Work at the 711 Institute How to Make a Submarine Quiet The Floating Raft: Isolating Engine Vibration The Hangor Class Deal With Pakistan The Engine Ban That Stopped Everything From Launch to Live Fire What Comes Next for China's AIP Submarines China publishes few official specifications for the Type 039C. Where figures are estimates or analyst assessments, the narration says so. Subscribe to Modus Assembly for accurate, engineering-first documentaries on how China builds its warships, submarines, aircraft and mega-machines. #Type039C #Submarine #ChineseNavy #AIP #HowItsMade Disclaimer: Synthetic Media & Content Generation The visual and audio content in this video, including voiceovers and photorealistic representations of aerospace and industrial environments, was generated using advanced artificial intelligence tools. Modus Assembly utilizes AI strictly as a visualization and production mechanism. This content complies with YouTube's Altered and Synthetic Content policies.