Taegisan-class cruiser

<imgur w="300px">kz9Qd4I.png</imgur> Taegisan as she appeared upon commissioning.
Class overview
Name:	Taegisan-class cruiser
Operators:	Greater Menghean Empire
Preceded by:	Madaesan-class cruiser
Succeeded by:	Hasŏlsan-class cruiser
Subclasses:	Obongsan-class cruiser
Built:	1930-1935
In service:	1933-1945
Planned:	4
Completed:	4
Lost:	2
Retired:	2
General characteristics Taegisan, 1933
Type:	Heavy cruiser
Displacement:	12,000 tonnes standard 13,200 tonnes full load
Length:	189.0 m at waterline 194.9 m overall
Beam:	20.4 m
Draught:	6.95 m (normal) 7.16 m (full load)
Propulsion:	4 steam turbines, 100,000 shp total 8 three-drum boilers 2 shafts
Speed:	32.4 knots
Range:	5,000 nm (9,260 km) at 15 knots
Complement:	802
Armament:	4 × 2 200mm L/50 Type 29 naval gun 4 × 2 100mm L/40 Type 28 AA gun 8 × 12.5mm mg (8×1) 4 × 2 550mm trainable torpedo tube
Aircraft carried:	1 × Donghae Type 32 floatplane
Aviation facilities:	1 × catapult, recovery crane

The Taegisan-class cruisers (Menghean 태기산급 순양함 / 泰岐山級巡洋艦, Taegisan-gŭb Sunyangham), known to the allies as the Thai Kee San class, were a group of four heavy cruisers built in the Greater Menghean Empire during the 1930s. An improvement upon the Madaesan-class cruiser design, they retained the same general characteristics as their predecessors, with four twin 200mm turrets, strong armor and torpedo protection, but a relatively low top speed. Their main improvements came in the form of a more streamlined hull design with integrated torpedo protection. Two ships were lost in combat, and the remaining two were in drydock under repair at the war's end; both were broken up for scrap after Menghe's surrender.

Background

After the signing of the "cruiser amendment" to the Nine-Power Naval Treaty in 1930, Septentrion's major naval powers were given upper limits on the total tonnage of heavy cruisers they could construct, and were forbidden from building any cruiser with a standard displacement of over 12,000 long tons. This limitation pushed Menghean naval engineers to further improve upon the Madaesan design, which, while well-protected, was in many respects sub-optimal.

At the time, the IMN was still operating under a conservative leadership, which viewed coastal defense as the Navy's main objective. As such, they required that any new design meet the same basic specifications of the Madaesan class: 150mm belt armor, 75mm deck armor, and a main battery of eight 200mm guns. This, in combination with the accelerated design schedule, meant using the same 100,000-shp powerplant from the preceding class. In the hopes of squeezing a little more speed out of the design, the engineers behind the project adopted a longer, somewhat sleeker hull form with a shallower draft. They also integrated the torpedo protection directly into the hull, rather than adding separate bulges to the outside. The result was a fairly resilient design, albeit a slow one, as the hull changes were found to deliver only a very modest increase in speed.

Design

Armament

The main battery of the Taegisan-class cruisers consisted of eight 200mm L/50 Type 29 naval guns in four two-gun "G-type" turrets, the same arrangement used on the preceding Madaesan class. Maximum range was 29,200 kilometers, and rate of fire 3 to 4 rounds per minute. Ammunition stowage totaled 200 complete rounds per gun, a mix of armor-piercing, high-explosive, and special anti-submarine shells and segmented powder charges. The turrets themselves were protected by 200mm of armor on the face and 150mm of armor on the sides, with 150mm barbettes.

In contrast to the Madaesans, which had been armed with six individual 100mm high-angle guns for anti-air defense, the Taegisans were designed with eight 100mm L/40 Type 28 anti-air guns in four twin mounts. Obongsan, the last ship in the series, was modified during construction and carried a third pair of twin guns flanking the aft mast. As built, the first three ships had a small-caliber AA armament of eight single 12.5mm machine guns, but this was steadily improved over the course of the war to include an array of Type 38 anti-aircraft guns.

Torpedo armament underwent a modest reduction during the design process, from four triple to four twin tubes, two sets on each side. These fired the extended-range 550-millimeter Type 23-II torpedo, which had a range of 11,000 meters at its lowest speed setting of 31 knots. Eight additional on-board reloads were carried.

Protection

<imgur thumb="yes" w="300" comment="Cross-section scheme of the armor scheme on the Taegisan; note the thick belt and deck armor and the torpedo protection.">OGxpKoP.png</imgur> The above-water armor scheme of the Taegisan-class cruisers was very similar to that on the preceding Madaesans. The main armor belt was 150 millimeters thick, running along the outside of the ship from the forward magazines to the aft ones. The deck armor was 75 millimeters thick, again covering the magazines, engine space, and internal control rooms. As on the Madaesans, the citadel and armor belts only extended a short distance above the waterline, providing good protection against critical hits from relatively short distances but little protection against flooding from small-caliber hits just above the waterline.

Underwater protection, by contrast, was very different. The torpedo defense system was directly contained within the streamlined hull, rather than being added outside in the form of anti-torpedo bulges. It consisted of a 50-millimeter armor plate which extended vertically from the bottom of the hull at a distance of roughly 1.5 meters from the outer layer. At about 4 meters above the base of the hull, this torpedo bulkhead curved outward to meet the bottom of the main armor belt. This created a pocket of watertight air compartments between the bulkhead and the water outside, with a layer of fuel storage tanks on the inner side. The designers anticipated that this configuration would divert the air from the torpedo explosion upward and outward, minimizing the risk of flooding in the citadel and reducing damage to the layer of fuel tanks. A similar torpedo protection scheme would be applied to some later treaty battleship proposals, though ultimately the Hyangchun-class battleships used an angled belt extending deep below the waterline.

Maneuverability

<imgur thumb="yes" w="500" comment="Color-coded lengthwise cross-section showing the internal systems and armor.">BmAFCnj.png</imgur> The powerplant used in the Taegisan-class cruisers was a direct carry-over from that on their predecessors: eight oil-fueled boilers hooked up to four geared steam turbines, with a total output of 100,000 shaft horsepower. In the construction of the new class, the designers made some minor changes to the machinery in an effort to squeeze more out of the displacement limit, shaving down thicker parts and using lighter alloys for some components. This succeeded in reducing the overall weight of the powerplant assembly by 3.6% while keeping maximum output constant.

The designers of the new class had hoped that by streamlining the hull they could achieve greater gains in speed over the Madaesan class despite limiting themselves to the same displacement and power. The higher length-to-beam ratio in particular was expected to increase efficiency. Actual trials, however, revealed that at normal displacement the Taegisan could only reach 32.4 knots, a fifth of a knot faster than the Madaesan and still two knots slower than most treaty-limit cruisers.

This tradeoff primarily reflected the insistence of the then-current IMN leadership that all heavy cruisers possess thick enough armor to withstand 8-inch shells from other heavy cruisers over a generous span of possible combat ranges. Only on the following series of Hasŏlsan-class cruisers would the Navy's new leadership turn its attention to speed, even then retaining fairly generous citadel and torpedo protection.

Ships in the class

In keeping with the tradition which the Madaesans started, all four ships in the class were named after mountains, and thus all of their names include the final character "san" (山). Obongsan, completed after war with Sylva had broken out and after Menghe withdrew from the treaty limitations, was completed with an additional pair of twin 100mm anti-air guns aft, as well as separate fire-control towers for them, and is sometimes considered a unique subclass.

Name	Name (Stuart-Lavender)	Mengja	Laid down	Commissioned	Fate
Taegisan	Thai Kee San	泰岐山	1930	1933	Under conversion to an anti-aircraft cruiser beginning in December 1943; scrapped in 1946.
Munsusan	Moon Soo San	文水山	1930	1934	Sunk by Columbian aircraft at the Battle of Swartzburg in October 1940.
Johangsan	Cho Hang San	鳥項山	1931	1934	In drydock between 1944 and 1945; scrapped at the war's end.
Obongsan	Oh Pong San	五峰山	1932	1935	Sunk by HMS Warchild at the Battle of Hathi Point, 1940.

Operational history

When Menghe declared war on Sylva on 7 May 1935, three Taegisan-class cruisers were already in service, with the fourth, Obongsan, still in fitting-out. Together, they formed the Third Cruiser Division, with Taegisan as the flagship. They took part in the Battle of Altagracia, bombarding shore positions after the battleships battleships Anchŏn and Haeju finished disabling the larger coastal defense batteries.

Khalistan campaign

All four ships saw combat at the Battle of the Portcullia Strait, where they escorted the First Battleship Division (consisting of the two Anchŏn-class battleships). None of them took serious damage, as the battleships drew most of the fire, and they were able to support the Axis landings on Portcullia and Khalistan proper in the following months.

As Menghe had entered the war against New Tyran, Dayashina issued the IMN a production license for the Type 93 torpedo in 1938, and in January 1940 the four cruisers were taken into port for repairs and refitted with twin launchers for the new weapon. They also had their medium-caliber AA armament substantially improved, through the addition of twin mounts for the Type 38 anti-aircraft gun.

The Third Cruiser Division saw combat again at the Battle of Hathi Point, where they once again confronted the Tyrannian battleship HMS Warchild. The Johangsan was absent for this engagement, as she had sustained bomb damage before the operation began and had to remain in port for repairs. Due to poor reconnaissance and nighttime conditions, the commander of the Menghean cruiser column did not initially recognize that HMS Warchild was among the attacking ships, and failed to coordinate his defense properly. Obongsan was lost during the engagement, with Taegisan and Munsusan escaping under the cover of darkness. Taegisan sunk one ship, the light cruiser HMS Dagger, and Munsusan claimed to have disabled the HMS Centurion even though the damage to the latter was actually fairly minor.

Anti-aircraft conversion

By 1943, the IMN concluded that the two surviving Taegisan-class cruisers were too slow for independent operations as cruisers; certain Columbian battleships could even overtake them. Throughout 1942 and 1943, they had mainly served as escorts for aircraft carriers, with Johangsan taking severe damage from dive bombers in the process. In order to improve their effectiveness in the new role, the Navy ordered that both ships be rebuilt as anti-aircraft cruisers during their repairs.

The general scheme of this plan was to remove the twin 200mm turrets and replace them with dual-purpose quadruple (or "double-twin") turrets mounting the 130mm L/55 Type 32 naval gun. These would fit atop the original barbettes and hoist ammunition from the below-water magazines. Medium-range anti-aircraft armament would also be improved, through the addition of stabilized, water-cooled quadruple 37mm AA guns. Sources disagree on whether the torpedo tubes would have been removed or retained in this configuration.

The original proposal called for the reconstruction of both ships to be completed before the end of 1944, but due to material shortages and the collapse of Menghe's wartime economy, neither conversion was finished by the war's end. Taegisan, which had been taken into drydock with only minimal damage, was fitted with two of the new turrets by the time of Menghe's surrender, but neither was operational; work on Johangsan had barely progressed at all, as no suitable drydocks were available.

See also

• Sŏnsan-class destroyer