The ability to keep your submarine designs secret may confer a tactical or strategic advantage in the future. Yet they are also massive projects which most countries cannot keep completely secret. The US Navy’s submarine building plans for example, are known years in advance. Not in China. On May 12 2021 we got our first view of a new submarine which was ready to be launched at a shipyard in Wuhan. This creates a lot of analysis, and some wild speculation.
Since May a brief segment of video and another candid photograph have come to light, enabling a deeper analysis. The submarine is currently on the Huangpu River in Shanghai, in the vicinity of 31°15’22.49″N, 121°32’38.71″E.
Before dealing with what we know, we should highlight something which we do not. We don’t know it’s name or designation.
Western observers have taken to referring to it as the Type-039C or –D. The last letter refers to it being either the third or forth (depending on who you ask) major variant of the existing Type-039A Yuan Class. These letters, including for the previous -B model, have been given by Western observers. Although they are widely used in defense circles, and I myself have been guilty of this, the Chinese Navy hasn’t shared their actual designations. So all of these might be wrong.
By far the most distinctive feature of the new submarine is the sail. This has an angled upper section with an angled chine running along it. The angles created resemble the fuselages of stealth fighter planes and may reduce its radar cross-section when it is on the surface. This would make it more stealthy when entering or leaving port. We can speculate that it may have hydrodynamic advantages, such as reducing the wake while at periscope depth.
The reshaped sail also creates significant volume near its top which may be used to house new systems. However, overall the sail is not larger than the previous Yuan class boats. So unless there is a significant reduction in the size of the masts, it seems unlikely that houses anything substantial.
Swedish Influence? The A-26 Class
Because of the angled sail there is a natural comparison with the Swedish A-26 Blekinge Class submarine. Superficially it look similar. And it is possible that the Swedish design, which has been public for many years, was an inspiration. But on closer examination there is only a general resemblance and they are actually quite different.
The Swedish submarine features much more blended lines with a curved leading edge of the sail merging seamlessly into the casing. The Chinese boat has a much straighter leading edge and less blended lower section. The hydroplanes are also positioned differently with the Swedish ones being along the line of the chine. The Chinese boat has them in the same position as previous Yuan class boats, which places them lower and further forward.
Unlike many countries building non-nuclear submarines, including the Swedes, Chinese designers have not adopted X-form rudders. Instead the traditional cruciform arrangement is retained. The upper rudder now has a towed array sonar (TAS) cable running through it. This may hint at a significant sensor upgrade for the class as previous Yuans had not been reported with towed arrays.
While comparisons with the Swedish A-26 are natural, it is worth noting that Chinese designers have come up with similar ideas in the past. Angled faces where added to the upper section of aType-035 Ming class submarine in around 2010. Only a small part was modified so it wouldn’t have had much effect when the boat was fully surfaced. But it may have been beneficial when only this section was above the waves.
It’s also too long ago to suggest that it was directly related to the new submarine, but it shows that the thinking was already there. So with this in mind observers should not rush to brand the new boat a copy of the A-26.
Overall the Swedish A-26 is a less compromised design, while the Chinese one is constrained by the pre-existing structure of the Yuan class. In essence it is a radical reshaping of the sail and, to an extent the casing, but still on the same frame.
This does not take away from the potential potency of the new submarine. But it does cast it as an iterative improvement of the Yuan Class rather than an all-new submarine.
Overall the new boat is approximately the same length as the earlier Yuans. This suggests that it hasn’t had an extra compartment added to accommodate vertical launch tubes for missiles. Or some radically new power plant.
These submarines are also equipped with Air independent Power (AIP). This likely uses a closed-cycle Stirling engine, similar to that on the A-26 class, to power the submarine when submerged. This means that it doesn’t have to snorkel to run its diesel generators, to recharge the batteries. Being able to run submerged for much longer greatly increases stealth. The trade-off is that the AIP generates less power so the submarine has to move slowly.
Note that the AIP powers the electric motor directly. It is a common misunderstanding that it recharges the batteries in lieu of the diesel generator. For this reason the diesels are retained.
There is speculation that China may have fitted lithium-ion batteries. These offer a much greater power density and may even make AIP unnecessary. However experts cannot agree and it is a cae of wait and see,
Like previous Yuan Class boats it is likely to be armed with a range of weapons including wire guided torpedoes, anti-ship missiles and mines. And there is the possibly that it can carry land-attack cruise missiles, shot out through the torpedo tubes.
The new submarine may be experimental, or possibly for export, so there is lots more that we do not know. The element of mystique is partly what will keep observers watching it more closely than other types.