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SSM Jiangnan / Lookout Tower - small submarine

SSM Jiangnan small submarine In October 2018, China Jiangnan Shipbuilding Group released a video promoting employees' advanced deeds, which revealed a new submarine that had never been seen before. From the exterior, this submarine is a drop-shaped design with a very refined appearance. However, from the public pictures, this submarine turned out to be "headless". This refers to the fact that this submarine does not have a tall submarine control tower or a submarine bridge called a "hull", and only a small arc-shaped protrusion at the position of the control tower. The "headless" submarine's unique appearance quickly caused speculation among foreign military analysts. Analysts offered a lot of ideas, but later found that there were more mysteries.

After China's "headless" submarine was first made public, some foreign professional magazines considered it to be an "unmanned submarine", mainly used for special operations or scientific experiments. However, the subsequent analysis of the photos refuted this point. The latest submarine water photos clearly show the crew standing on it.

Analysis of commercial satellite imagery, which caught the new submarine outside the shipyard, demonstrated that he is 150 feet long and with a beam of about 15 feet. Viewed from the outside, the length of the submarine disclosed by Jiangnan Shipbuilding Group is not large. The length of the submarines is less than 50 meters, so Chinese observers suggested that the displacement may be less than 1,000 tons. This tonnage can only be regarded as a small submarine. Compared with the size of modern submarines, normal conventional submarines are above 2,000 tons, and the largest can be above 5,000 tons.

SSM Jiangnan small submarine From the size and perspective, most foreign analysts believed that this "headless" submarine is not a nuclear submarine and should be conventional power. China currently has AIP technology, so this submarine is likely to be equipped with such airless underwater power units. However, some analysts have come to a more striking conclusion-this is a "fully electric submarine", which is not equipped with a diesel engine and is completely powered by lithium batteries. Analysts believe that this submarine can not see the traces of the snorkel, which is a necessary equipment for diesel-electric submarines. In addition, China is the world's largest lithium producer and one of the most advanced countries in lithium battery technology, leading the world in electric vehicle technology. Therefore, it is not impossible for China to develop an "all-electric submarine" like an electric vehicle. If China can really break through the technology of "all-electric submarines," it will be like an electric vehicle, and it will completely change the direction of submarine development.

For an unmanned submarine, the hull of this size is too large. So far no country has used such a large unmanned submarine, and there are no missions that require remote control. This is considerably larger than the US Navy's Large Scale Vehicle LSV II, an unmanned hydrodynamic/ hydroacoustic/ flow management/ maneuvering test object that was 111 feet long with a beam of 10 feet and nominal displacement of about 200 tons. The new "headless" submarine would appear to have about three times of volume of the LSV II, suggesting a displacement of about 600 tons. This is about a quarter the displacement of the currrent Yuan-class Type 039A conventionally powered submarine.

In contrast, in the United States, the Advanced SEAL Delivery System (ASDS) was intended [prior to cancellation] to be a long-range submersible that displaced 60 long tons with a beam of 6.75-feet, a height of 8.25-feet, and overall length of 65.2 feet. The operational MK VIII MOD 1 SEAL Delivery Vehicle is a free-flooding wet submersible designed for undersea special operations including direct action, hydrographic reconnaissance and insertion/extraction of SEALs. SDVs can be inserted into the water via a DDS-equipped submarine, or surface ships. An SDV is a wet submersible designed to carry combat swimmers on missions that include underwater mapping, recovery of lost objects, reconnaissance, and destruction of enemy harbor facilities or the naval order of battle.

SSM Jiangnan small submarine For decades, in order to increase the underwater speed of submarines, the shape of submarine conning towers has also been continuously improved. The original purpose of the conning tower was to provide a station from which the ship could be conned while sailing on the surface, which was the normal condition of early submersibles. Submarine conning towers are becoming more sleek to reduce drag in the water, such as German 212A and 216 conventional submarines and Russian "Alpha" and "Akula" nuclear submarines. But entirely eliminating the conning tower is more like a once and for all approach.

"Headless" submarines have appeared in history, such as the Soviet Union's Type 673 test nuclear submarine. The submarine proposed plan in the 1960s, but because it was too advanced, it stayed on the drawing. According to the design, the Type 673 nuclear submarine used an all-titanium hull, a 155 MW liquid metal cooling reactor, and an output of 40,000 horsepower. The underwater displacement of the 673 nuclear submarine was estimated to be 2,200 tons, with a total length of 66 meters, a maximum underwater speed of up to 40 knots, a cruise speed of 25 knots, a maximum practical depth of 600 meters, and a limit depth of 1300 meters. The nuclear submarine requires only 35 crew members and is equipped with six 533 mm torpedo tubes.

The 673 submarine completely eliminated the command tower, and the periscope, snorkel and other equipment protruded directly from the hull. After all the telescopic equipment is retracted, the entire submarine looks like a complete water drop. This high-speed nuclear submarine was regarded by the former Soviet Union as an "underwater interceptor" to assault enemy strategic nuclear submarines. Because the design was too advanced, many of the 673's technologies could not be realized with the reserves at the time, so the submarine only left design drawings. However, part of the technology of the 673 nuclear submarine is applied to the famous 705 "Alpha" class attack nuclear submarine. The latter still maintains the highest underwater speed record of nuclear submarines (39 knots).

The fairwater sail or bridge fin is a totally undesirable appendage when viewed from any hydrodynamic or hydrostatic aspect or, indeed, from any other aspect including stealth. It causes considerable drag high above the centreline axis which causes a bow-up pitching moment which, in turn, overrides the other hydrodynamic effects on the hull and so determines the settings required on the forward and after hydroplanes to allow the submarine to maintain a straight and level path. When the submarine is heeled into a turn, the bridge fin causes lift which can result in a "snap-roll". For this reason, some Navies have adopted separate two-man control for planes and helm thus increasing crew size. At speed, this fin can generate vortices which produce noise. When surfaced, it is the single most visible and characteristic appendage of a submarine--typically offering over 350 square feet of visible area well above the waterline which announces "submarine" to any observer. It also adds considerable weight topside which is the worst possible place.

The hull of a 688 class submarine is about 33 feet in diameter but, because of the bridge fin, draws some 50 feet of water submerged. Furthermore, at periscope depth, the top of the bridge fin is only a few feet under water where wave motion can affect the stability of the submarine and where there is a risk of collision--particularly in crowded coastal waters. The only reason this appendage exists is because it is a convenient place to locate periscopes, antennas, snorkels, and a surface piloting or bridge position. In addition, the location of the control room underneath the bridge fin is dictated by the need to have the periscopes available there. The amount of space required by the periscopes also makes the control room much larger than would otherwise be necessary.

SSM Jiangnan small submarine According to commercial satellite images from September 2019, the submarine is 150 feet long and about 15 feet wide. H.I.Sut+ton initially estimated it to be slightly smaller, but the compact hull still far exceeds a small submarine. From satellite image analysis, the submarine is undergoing some kind of test from the shipyard and has not yet been deployed to the combat base. This submarine has a unique design. There is no fin-shaped lookout tower that has been indispensable to all submarines so far. There is only a small protrusion at the position of the lookout tower. One theory is that this is a crewless submarine, so there is no need for a watchtower for the captain when sailing on the surface. In this way, it should be the world's largest autonomous submarine (AUV). A large autonomous submarine recently disclosed by China is a dwarf in front of it. But Sutton believes that it is not a large autonomous submarine, it is probably just a test submarine, the purpose is to evaluate the bold design concept of the Chinese attack submarine in the future.

What also attracted the attention of analysts was that the submarine did not have indications of torpedo launch tube, or even sonar. Therefore, the use of this submarine was elusive. The public video of Jiangnan Shipbuilding Group is very clear. The entire hull of the new submarine can be seen clearly, but the bow of the hull is smooth, and the traditional round torpedo launch ports cannot be seen. on other new submarines it is possible to clearly identify the torpedo launch ports before launching. There are several possibilities. One is the superb construction technology of Chinese submarine launch tubes, which can be completely traceless. The other explanation is that this new type of submarine is a test model and is only used for certain underwater tests, such as testing high speed.

A submarine of less than 1,000-ton is not suitable for long-distance operations, and its weaponry is also restricted. None of the major military powers has developed combat submarines of this level. Chinese observers suggest that the main purpose of this submarine is not combat, but a platform for technical verification.

Some suggested it was conventional submarine single-hull hull technology test boat. For the domestic conventional submarine to entered the era of single-hull submarines would be a historic leap forward for domestic conventional submarines. Previously, domestic conventional submarines used double hulls. The advantages of double hulls are large reserve buoyancy and strong survivability. The disadvantage is that the same equipment is installed, the size and displacement of the submarine are larger, and the exposed area of the submarine in front of the sonar is larger and easier to find. Today, with the increasing popularity of low-frequency active sonars, this shortcoming cannot be ignored. In addition, larger size and displacement also mean greater resistance, and higher requirements for submarine power.

Most modern submarines constructed in the West utilize a single Pressure Hull configuration with the Main Ballast Tanks (MBT) situated at the fore and aft ends of the submarine. Typically, the reserve of buoyancy (ROB) is in the order of 11% of the surfaced displacement of the boat. A better distribution of weights is achieved by incorporating some of the MBT capacity in a midship location which results in better balance and handling, particularly when the submarine is surfaced.

Some older designs (e.g. Skipjack and Permit classes) had such a configuration. However, the incorporation of these tanks was the result of giving the Pressure Hull (PH) a complicated and less than ideal shape in order to withstand deep diving pressure. Where the midship MBTs were located, the PH was narrowed or waisted, thus allowing the resulting space between the PH and the outer hull to be used for MBTs. This narrowing of the hull was accomplished by welding circular conical sections to the cylindrical PH sections. This gave rise to undesirable stress areas where the conical sections joined the cylindrical sections and which had to be met with heavy scantlings and bulkheads. In addition, the safety margin offered by a ROB of only 11% is very small. Should an incident take place at depth that produces a breach of the pressure hull and renders inoperative some MBTs, a subsequent emergency blow might be insufficient to establish positive buoyancy and the boat may sink.

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Page last modified: 01-08-2021 14:08:54 ZULU