The Type 039 submarine (NATO reporting name: Song-class) is a class of diesel-electric submarines of the People's Liberation Army Navy. The class is the first diesel-electric submarine to be fully developed within China and also the first Chinese diesel-electric submarine to use the modern teardrop hull shape.
The British U-class submarines (officially "War Emergency 1940 and 1941 programmes, short hull ") were a class of 49 small submarines built just before and during the Second World War. The class is sometimes known as the Undine class, after the first submarine built. A further development was the British V-class submarine of 1942.
