Taean-class cruiser
| File:CL Taean 1932.png Taean as commissioned.
| |
| Class overview | |
|---|---|
| Name: | Taean-class cruiser |
| Operators: | Greater Menghean Empire |
| Preceded by: | Ichŏn-class cruiser |
| Succeeded by: | Sunchang-class cruiser |
| Subclasses: | Jinan-class cruiser |
| Built: | 1928-1933 |
| In service: | 1932-1943 |
| Planned: | 4 |
| Completed: | 4 (2 as Jinan subclass) |
| Lost: | 2 |
| General characteristics Taean, as built | |
| Type: | Light cruiser |
| Displacement: |
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| Length: |
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| Beam: | 16.8 m |
| Draught: |
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| Propulsion: |
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| Speed: | 31.6 knots |
| Range: | 5,000 nm (9,260 km) at 15 knots |
| Complement: | 268 |
| Armament: |
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The Taean-class (Menghean: 태안급 순양함 / 泰安級巡洋艦, Taean-gŭb Sunyangham) were a pair of warships - four if the Jinan subclass is included - built for the Greater Menghean Empire in the early 1930s. They were the first Menghean light cruisers to carry all of their main guns in fully enclosed multi-gun turrets on barbettes. Well-armed and well-protected, they were intended to operate as fleet scouts and skirmishing surface combatants, and they carried two-thirds of their main guns facing astern so that they could fight effectively while retreating. They were known to the Allies as the Tai Ahn class.
Originally designed as heavy cruisers, they were completed as light cruisers and converted back to heavy cruisers in 1937. These changes were accomplished by switching out the triple 150mm turrets for twin 200mm ones, as the barbettes were designed to accommodate both. Even with this intentional treaty loophole built in, the ships were pared to the bone in an effort to minimize displacement, and the new turrets were cramped and uncomfortable. They also suffered from a low top speed and a constrained rate of fire.
Pre-commissioning trials with the completed Taean revealed a number of structural problems, including fears that welds around the barbettes could crack under the strain from firing refitted 200mm guns. As a result of these findings, the second two hulls under construction, Jinan and Inje, were completed to a slightly different configuration. Due to their revised secondary armament, new powerplant, and higher displacement, they are sometimes considered a separate class of warship - the Jinan-class cruiser.
Development
Although the ships would not come to fruition until after Kwon Chong-hoon's coup, preliminary design work on what would become the Taean-class cruiser actually began in the 1920s under the Federative Republic of Menghe. Independent Navy design studies, the first of which dated to 1924, explored the feasibility of a compact, heavily armed cruiser to sortie against enemy light and heavy cruisers approaching Menghean waters. The recently-signed Nine-Power Naval Limitation Treaty did not place any limitations on warships displacing under 12,000 tonnes, and the Menghean Navy leadership, still concerned over encroachment from imperialist naval powers, believed that a focus on small, fast, heavily armed surface combatants could help counterbalance other powers' advantages in capital ship tonnage.
The first ship in the series, Taean, was laid down in 1928, after the new government of the Greater Menghean Empire authorized funding for the construction of four cruisers in the "B-series" blueprint family. The final design featured a heavy armor scheme and three 200mm twin-gun turrets, making the ship closer to a small heavy cruiser in terms of its combat capabilities. Early-stage work on the new cruisers proceeded simultaneously with the fitting-out of the Madaesan-class heavy cruisers, which displaced 12,000 tonnes and were armed with eight 200mm guns in four turrets.
The signing of the 1930 addendum to the Nine-Power Naval Treaty imposed new restrictions on cruiser construction, forcing the Imperial Menghean Navy to modify the Taean's final design. Under the new terms, Menghe could build no more than 10 cruisers with guns exceeding 6.1 inches (155mm) in caliber, and total displacement in this category was limited to 96,000 tonnes. Light cruiser aggregate displacement was limited to 108,000 tonnes, which far exceeded Menghe's need for scouting and patrol ships. Consequently, the Taean and her sister ships were completed to modified specifications, with new three-gun 150mm turrets. This allowed the IMN to classify them as "light cruisers," even though in theory they could still be retrofitted with twin 200mm turrets.
Design
General characteristics
The Taean-class cruisers featured a distinct profile with aft-heavy turrets and a low superstructure which could make them difficult to spot near the horizon. They can most easily be distinguished from the Jinan subclass by the arrangement of their funnels: the first two are trunked together into a single double-wide structure, whereas the Jinan and Inje had two larger funnels of equal size. The arrangement of the two classes' bridges also differed somewhat, as did the placement of their aft masts and seaplane recovery equipment.
In an effort to save weight and leave more aggregate displacement for other light cruisers, the hull design was modified during construction to make greater use of welding in sections above the waterline. The overall effect on tonnage was relatively minor, but the poor implementation of welding would create problems with structural integrity later on.
For reconnaissance and target spotting, each cruiser was built to carry two float planes, one on a dedicated service platform and one on a catapult abaft it. These were recovered from alongside the ship by means of a crane attached to the aft mast. Initially, the only available reconnaissance plane was a variant of the Chikai Type 27 fighter with floats, but the crane and catapult were both built with heavier future aircraft in mind, and could launch and recover the Namtong Type 36 and Yusin Type 41 floatplanes without difficulty. By the middle of the war ,though, only a single floatplane was carried, the storage and service platform having been converted to mounting space for additional anti-aircraft guns.
In addition to their floatplanes, the cruisers could carry six small boats each, usually four wooden-hulled dinghies and two powered launches.
Armament
As built, the Taean class was armed with nine 150mm L/50 Type 31 guns in three triple turrets. Two of these turrets faced aft in a superfiring arrangement, allowing the ship to bring the majority of its guns to bear on the enemy while retreating. Conversely, only one turret could fire directly forward, which was not optimal when pursuing destroyers or other light cruisers. Main battery ammunition totaled 1,260 rounds, or 140 per gun. Each turret was equipped with a co-incidence rangefinder, and additional rangefinders on the superstructure and tower could direct fire centrally. Main gun range was 26,200 meters at an elevation of 45 degrees, but elevations as high as 50 degrees were possible, to provide steeper plunging angles against an enemy ship's deck. The guns were not capable of anti-aircraft fire.
The use of 150mm turrets in the final design was a response to the 1930 amendment to the Septentrion Nine-Power Naval Treaty, which defined a "heavy cruiser" as a warship carrying a gun exceeding 6.1 inches in caliber. Not wanting to detract from its more limited heavy cruiser tonnage, the Navy completed the ships as light cruisers, applying the same changes to the Jinan subclass/successor class. To bypass the treaty restrictions, however, Menghe secretly completed fifteen 200-millimeter twin turrets built to the dimensions of the Taean's barbettes, enough to equip four warships while leaving three spares. These were installed on the Jinan and Inje in 1935, and refitted to the Taean and Kangjin in 1937, after Menghe's withdrawal from the collapsing naval treaty. The leftover 150mm turrets were installed on a new class of floatplane tender, and six were stockpiled for use as secondary mounts on the Insŏng-class battleships, which were never completed.
The twin 200mm turrets were notoriously cramped, a result of the requirement that they fit into narrow barbettes and minimize weight above the waterline. A full loading cycle took 25 seconds when the guns were at the proper elevation for loading, much slower than the firing cycle of 20mm guns on other Menghean cruisers of the period, and it could only be performed at an elevation of 10 degrees, further limiting the rate of fire at high elevations. The throw weight of two Menghean 200mm guns was 47% higher than the throw weight of three Menghean 150mm guns, and even though the barbettes were designed with higher recoil forces in mind, combat experience revealed that prolonged firing of the main battery could rupture certain welds in the hull structure. As the new shells and charges were also larger, stored ammunition capacity was lower, at 660 rounds total or 110 per gun.
The guns themselves were not individually sleeved, and could only elevate and fire as a pair. They were also placed closely together, which in firing trials was found to degrade accuracy: the muzzle blast from each gun interfered in the other projectile's initial trajectory. A solenoid timer intended to stagger the gun firings partially addressed this problem, at the cost of throwing off the second shell slightly if the ship was pitching or rolling. Maximum elevation on these turrets was +40 degrees, for a maximum range of 28,400 meters, and penetration at 17,000 meters amounted to five inches of belt armor.
Apart from the guns, the ships carried four triple 550mm torpedo launchers, two on each side. These fired the Type 23 torpedo, and later its successor the Type 23-II. The torpedo launch controls on top of the tubes were protected by a "gun shield" of unknown thickness, which provided the crew with some protection against shrapnel and the elements. Initially, no torpedo reloads were carried, though surviving wartime photographs from the Kangjin show six torpedoes attached to a rack underneath the floatplane launcher, likely for use when reloading the aft two torpedo launchers.
As on many other cruisers of the period, AA armament was initially quite poor but it rapidly improved as the war went on. The ships were built with four 100mm L/45 Type 29 flak guns in unarmored single mounts, just behind each of the torpedo launchers. These were supplemented by six twin 12.5mm water-cooled machine guns spread along the superstructure. During 1937 turret replacement, the flak guns were replaced with powered, shielded 100mm twin mounts, the same armament type on the completed Jinan and Inje. Additional single 12.5mm MGs were also added, and in time these would be replaced by a mix of 37.5mm and 20mm autocannons.
Protection
Armor protection for the Taean class was fairly good for a ship of her displacement, and reflected the IMN's initial plans to use her as a heavy cruiser and skirmishing scout ship. Her external main belt was 75 millimeters thick over the propulsion machinery and 50 millimeters thick over the magazines. The "turtleback" armored deck, which was 35 millimeters thick, angled down to meet the hull sides at the base of the main armored belt, meaning that shells descending at moderate angles would have to pass through both. The forward citadel bulkhead was 75 millimeters thick, and the aft bulkhead was a full 125 millimeters thick with a 50mm plate covering the rudder and steering equipment, again reflecting the expectation that these ships would trade shells with other cruisers while retreating. Additional 25mm box armor provided protection around the main gun magazines to compensate for the thinner main belt at these locations.
The main battery turrets were given 100mm of armor on the face, 50mm on the roof and cheeks, and 25mm on the rear and rear-sides. The barbettes they stood on were 75 millimeters thick. There was no internal plating in the turrets to separate the guns from one another, though a 10mm plate separated the loading space from the fire-control space in the rear. Armor protection was identical on the new turrets installed in 1937, though these turrets were slightly larger and therefore heavier overall.
Torpedo protection was much weaker than shell protection, as the designers were under pressure to minimize beam and thus salvage more speed from the powerplant. A double bottom covering 64% of the ships' length offered some protection from leaks, and the bow and aft sections were divided into watertight compartments, but the boiler and turbine rooms extended directly to the walls of the hull below water level. The ships' generators were immediately forward of the turbine rooms, meaning that any torpedo hit which flooded the machinery space was likely to disable the emergency power and water pumps as well. Kangjin paid the price for these sacrifices, capsizing quickly after being hit by a Columbian aircraft torpedo in 1941.
Propulsion
A drawback of the designers' emphasis on armament and protection was poor speed. The Taean and Kangjin could only manage 31.6 knots at standard load, not abysmal but slightly below the top speeds of most contemporary light cruisers and well below the 35+ knot speeds of the Gijang and Ichŏn classes that came before them. This constraint was deemed acceptable when they were intended as heavy cruisers, but as light cruisers they had trouble keeping up with enemy destroyers and could be overtaken by some heavy cruisers. The Jinan subclass would address this problem with a revised boiler configuration and more powerful turbines, allowing it to reach 33 knots, but this came at the cost of cramped machinery spaces and a higher displacement.
Built under the direction of the "old generation" of Naval upper commanders, the Taean-class also suffered from a relatively poor operational radius, a sacrifice made in the anticipation that they would mainly be fighting a defensive war close to Menghe's shores. In combination with their low speed, this prevented them from being used as commerce raiders or long-distance scouts in the Helian ocean; for most of the war, they remained relatively close to the shore. A proposed refit in 1939 would have added anti-torpedo bulges containing additional oil bunkers, a double solution to the problems of poor range and inadequate underwater protection, but these changes were ultimately postponed until the ships themselves were sunk.
Service history
Innominadan campaign
At the outbreak of war with Innominada, the Taean and Kangjin joined the IMN task force operating along the east coast of Innominada, where they were tasked with establishing naval supremacy and bombarding coastal positions in support of ground troops. They saw no ship-on-ship combat, but they did come under repeated attack from Sylvan aircraft based further inland. Taean struck a mine on October 4th, 1936, while supporting amphibious landings near Las Playas. Two of her forward watertight compartments flooded, but she remained operational, and was able to return to Dongchŏn at reduced speed under her own power. Kangjin, which had suffered minor damage from near-miss bomb attacks, withdrew as well, with the new cruisers Jinan and Inje moving up to replace them.
During the cruisers' refits in Dongchŏn, the Navy took their drydocked status as an opportunity to apply additional upgrades and modifications. The twin 200mm turrets were brought out of storage and installed in place of the triple 150mm guns, and the AA battery was upgraded to four twin 100mm guns in partially shielded, power-assisted mounts. The ships also received triple 610mm torpedo launchers in place of their existing mounts, allowing them to fire the longer-ranged Type 35 torpedo, a licensed copy of the Dayashinese "Long Lance." The aft mounts had on-board reloading capability, but the forward ones did not.
Khalistan campaign
Taean and Kangjin both took part in the Battle of the Portcullia Strait, where they accompanied the Second Battleship Division during its maneuver to lure Task Force Q toward the main battle line. Kangjin in particular sustained heavy fire to her quarterdeck from other cruisers, but true to her design, her aft-facing armor held and neither her rudder nor her turbines were disabled. While Kangjin was undergoing repairs, Taean took part in the bombardment of Portcullia itself during the joint Menghean-Dayashinese amphibious operation there.
Battle of Swartzburg
Kangjin finally succumbed to enemy fire at the Battle of Swartzburg, shortly after the OSC's entry into the war. When the second wave of Columbian aircraft arrived on October 29th, a torpedo dropped by a Douglas A-20 Havoc struck her amidships, right next to the bulkhead separating the two boiler rooms. Her machinery spaces quickly flooded with water, disabling her generators and emergency pumps. Her captain ordered the crew to manually seal all other compartments, but the machinery spaces alone brought in an enormous volume of water, and less than 10 minutes after impact she split in two under the strain and began to sink.
Ships in class
Surviving Navy procurement records indicate that when initially ordered, the Taean-class cruisers would have been named after mountains, in keeping with the heavy cruiser nomenclature used on the Madaesan class. The first ship was to have been called Taegisan, and the second Chŏnggyesan; the remaining two ships were unnamed at the time of ordering, as they had not been laid down.
After their treaty-compliant modification, the two hulls in drydock were renamed after Menghean prefectures to remain consistent with the naming of past light cruisers. The name Taegisan was reused for the first Taegisan-class cruiser, a "true" heavy cruiser laid down the same year, and Chŏnggyesan would be reused for a post-treaty heavy cruiser.
| Name | Mengja | Laid down | Commissioned | Fate |
|---|---|---|---|---|
| Taean | 泰安 | 1928 | 1932 | |
| Kangjin | 康津 | 1929 | 1933 | Sunk by Columbian torpedo bombers in 1940. |
See also