"Little ones" for the "gray wolves"
Submarine XXIII series goes on a campaign
History German "electric robots" are not limited to the ocean-going submarines of the XXI series. The Nazis did not plan to use large boats in small seas; special submarines were designed for this work. At the same time, technical innovations were to be implemented on them, as on ocean-going submarine cruisers... The Walter engine was no exception. Along with the XVIII series, the XVII was designed - with the same turbine on concentrated hydrogen peroxide, but with a much smaller displacement. Subsequently, the capacity of the steam-gas turbine was cut in half, and the project of the XXII series of boats was obtained. And in the same way, after it became clear that the Walter turbine "does not take off", they were redesigned for a conventional diesel-electric power plant, resulting in the submarines of the XXIII series.
The first "babies" of the Third Reich - submarines of the II series
The first German small submarines designed for action in the Baltic and North Seas were the U-boots of the II series. They fought well in 1939-1940, but then the submarine war was transferred to the Atlantic, and the "babies" were not welcomed, and their construction was stopped in 1940. But by 1943 the idea of using small submarines was again in the air.
Let's start with the fact that the Kriegsmarine had new theaters: the Mediterranean (where the Italian allies had previously operated) and the Black Sea. Sending submarines there via Gibraltarian was too expensive, and the decision naturally suggested itself to create submarines that could be transported by rail, if not entirely, then at least in parts, with subsequent assembly on site. And with the English fleet In the North Sea, fighting with VII-series submarines became... expensive: the British had raised anti-submarine defense against them to the level of an exact science, so losses were off the charts.
Grand Admiral Dönitz on the cramped bridge of a Type XXIII submarine
The proposal to design small submarines was made to Grand Admiral Karl Dönitz by the designer of the XXI series Olfken in June 1943. "Papa" supported the proposal, but set two conditions: the new boat should be armed with standard seven-meter torpedoes (instead of the shortened 5,5-meter ones, which were planned to be used on the small boats of the XXII series), and it should be able to be transported by rail. And the work began to boil, especially since the A. Grimm design bureau was given a little more than a month for everything...
However, the rapid design of the boat was facilitated by the fact that many of its parts and mechanisms had already been well developed by the German industry. In order not to be unfounded, I will only mention that the six-cylinder diesel MWM RS134S with a capacity of 575 horsepower was developed as a diesel generator for the Bismarck-class battleships, the AEG GU4463-8 propulsion electric motor with a capacity of 572 horsepower was the engine of the most common submarine in the Reich submarine forces, the VIIC series, and the storage battery was half of the AB of the older sisters - the U-boots of the IX series. Where else the BBC CCR188 sneaking electric motor with a capacity of 35 horsepower was used, I personally could not find, but surely the pragmatic Germans did not copy it out of thin air...
General drawing of the "baby"
The submarine that resulted from the work of German designers had a surface displacement of 234 tons, an underwater displacement of 275 tons, a length of 34,7 meters, a midship width of 3 meters, an average draft of 3,6 meters, and a height of 7,7 meters. For comparison, the Soviet submarines of the M "Malyutka" type had a maximum (there were five series of Malyutkas, which differed significantly in their performance characteristics) surface displacement of 208 tons, an underwater displacement of 258 tons, a length of 45 meters, and a midship width of 3,5 meters. What the "German" was much better at was its diving depth - the operating depth of the XXIII series was 180 meters, while the maximum for the "malyutka" was 60 meters... The surface speed of the "mini-electric robot" was 9,7 knots, and the underwater speed was 12,5 knots. The Soviet "baby" demonstrated more traditional characteristics in this regard - underwater speed of 7,8 knots, surface speed of 14 knots (however, all submarines from the Second World War, except for the German "electric robots", had a surface speed higher than the underwater speed).
Torpedo compartment of the mini-"electric robot"
The torpedo armament of the submarines was identical - two torpedo tubes in the bow. Moreover, if the first "babies" and the entire XXIII series did not have spare torpedoes, then the last series of Soviet small submarines already had spare torpedoes and the ability to reload the torpedo tubes. By the way, on the German submarine, reloading was carried out in an original way (approximately like in the Soviet joke about how our tonsils are torn through the anus): torpedoes were inserted directly into the torpedo tubes from the outside, for which the aft ballast tanks were filled with water until the torpedo tube covers were visible above the water. Yes, not only the French know a thing or two about perversions...
Nothing extra - the highest class of hydrodynamics of the 40s
Artillery The XXIII series boats did not carry, moreover, as in the case of the XXI series, the designers tried to minimize the number of protruding parts in the light hull - for the sake of good underwater hydrodynamics. Incidentally, this was a legacy from the XXII series boat project, with the "Walter turbine" they were supposed to have a fantastic underwater speed of 20 knots for those times.
Bow section of the XXIII series submarine
The boat's robust hull had the same figure-8 cross-section as the XXI series, in which the smaller, lower loop of the figure-4 was used to install the battery. The hull was assembled from four sections: aft, engine room, central post (combined with living space) and bow. Unlike the ocean "electric robots", whose sections were transported by barges, the sections of the small "electric robots" were transported by rail.
Compared to the XXI series boats, the small boats had significantly reduced electronic equipment. The XXIII series submarines did not have an active sonar, nor did they carry a radar. Guidance during torpedo firing was carried out as on the old VII and IX series boats. But a plexiglass cap was installed over the boat's bridge, which significantly reduced the unpleasant sensations of the upper watch in stormy weather. The habitability of the boats was... so-so, however, this concerned any small submarines, Soviet and English ones are no exception.
Initially, it was planned to build boats for the North Sea and the Baltic at the Deutsche Werft shipyards in Kiel and Gotenhafen, the Germania shipyard in Kiel, and the Howald Werke in Kiel and Hamburg. For the Mediterranean, boats were to be assembled at the Arsenal plant in Toulon and the Ansaldo shipyard in Genoa, and for the Black Sea... in Odessa! More precisely, at first they planned to build them at the Marti plant in Nikolayev, but the Red Army was advancing so quickly that the mouth of the Dnieper was no longer a safe place for the Germans. However, by the time the construction of the series began, Genoa, Toulon, and Odessa had become... irrelevant. So - only Germany!
The decision to build was made by Dönitz on August 5, 1943. The Deutsche Werf in Hamburg was chosen to begin construction: it was convenient in that the sections did not need to be shipped far - they were riveted nearby, in Finkenwerder (and it was decided to abandon the construction of the XX series transport boats, so production capacity was freed up).
According to the construction plan approved on December 6, 1943, it was planned to build 140 submarines of the XXIII series, of which 60 in the Mediterranean, 15 in the Adriatic, 15 in the Black Sea. The enormity of the plans, as usual, was broken by the actions of the Allies. Not only were the Mediterranean, Adriatic and Black Seas no longer a priority, but also armadas of Allied bombers regularly visited Hamburg, greatly interfering with the work. At a meeting in February 1944, it was said that due to the bombing, the delivery dates for parts for small submarines were postponed to March, and the delivery of the first boat itself - to December 1944. However, the Germans used the free time to make changes to the project: another 2,2-meter-long section was added, as a result of which the bow compartment became less cramped.
The first submarine, U-2321, was launched on April 17, 1944, on the birthday of a mediocre Austrian artist (yes, the Germans loved painting...). It was planned to build hundreds of these boats, but in reality it was necessary to "cut the sturgeon" significantly - 61 submarines of the XXIII series entered service, another 4 boats were 95% ready. Some of the boats were supposed to have a protective coating "Alberich" on their light hulls, consisting of two layers of sound-absorbing rubber. But in reality, only two submarines that entered service managed to be equipped with the coating. True, almost all the boats had their snorkels covered with porous rubber - this reduced their radar visibility.
Operating small boats was a real pain in the ass: they had very little buoyancy (10,5%), so when submerged they sank like a stone. On the one hand, this was convenient, since it allowed for a quick dive in case of danger, on the other... Sometimes, when starting to dive, a submarine of the XXIII series forgot to stop. So, during an emergency dive, the crew of U-2326 managed to stop only at 106 meters - they barely swam out... After the war, this boat was handed over to the French, they were much less lucky - during a dive, it sank near Toulon, taking the lives of 17 submariners.
It's spring 1945, and they're giving the Nazi salute...
However, unlike the XXI series boats, the small "electric boats" showed their best side in the last months of the war. Not a single one of them was lost during combat missions (seven submarines of this series were lost in harbors, during tests and passages). The first to go on combat patrol was U-2324, on January 18, 1945. The boat returned home without any problems, but also without any catch. The first sinking of an Allied vessel was attributed to U-2322: under the command of Senior Lieutenant Fridtjof Heckel, it sank the coastal vessel "Egholm" on February 25, 1945. On April 5, 1945, the coastal vessel "Gesray" was sunk by U-2321. The last merchant ships sunk by submarines during World War II were U-2336, under the command of Lieutenant Commander Emil Klussmeyer. She sank the ships Senland I and Avondale Park in the Firth of Forth on 7 May 1945. The latter ship was sunk at 23:03 - 57 minutes before Germany's official surrender.
The ending was a bit predictable...
After the war, most of the new German submarines (those that the Germans themselves did not manage to sink) were sunk by the British during Operation Dead Light - the Limeys did not want the revolutionary German U-boots to enrich the shipbuilding schools of the former allies.
H-31, formerly U-2353
Nevertheless, the USA and the USSR managed to recapture one each. Another pair was raised from the bottom in 1957 by the FRG - they entered the Bundesmarine under the names "Pike" and "Akula". In the Soviet Navy, the submarine U-2353 was named H-31 ("H" - German), later - M-31, from 1946 to 1948, specialists from the Central Research Institute of Military Shipbuilding worked closely with the boat, conducting full-scale tests, the results of which were later used in the development of domestic diesel submarines. She was scrapped in 1952.
The Swedes also got a XXIII series submarine after the war.
In general, oddly enough, the experience of operating the XXIII series submarines was much more positive for Germany than the ocean "electric robots". By the time they went on combat patrol in the ocean, the Allies' dominance was close to absolute, and in the coastal zone the new U-boots had a chance. And they used this chance...
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