Yŏng'il-class cruiser

<imgur w="300px">mfRBtrj.png</imgur> Yŏngil as she appeared in 1940.
Class overview
Name:	Yŏngil-class cruiser
Operators:	Greater Menghean Empire
Preceded by:	Boryŏng-class cruiser
Succeeded by:	Sangha-class cruiser (planned)
Built:	1938-1943
In service:	1940-1945
Planned:	6
Completed:	6
Lost:	3
Retired:	3
General characteristics Yŏngil, 1940
Type:	Light cruiser
Displacement:	7,400 long tons standard 8,230 long tons full load
Length:	181.2 m at waterline 188.0 m overall
Beam:	19.9 m
Draught:	5.45 m (normal) 5.63 m (full load)
Propulsion:	4 steam turbines, 100,000 shp total 8 three-drum boilers 4 shafts
Speed:	35.4 knots
Range:	4,000 nm (7,400 km) at 15 knots
Complement:	582
Armament:	3 × 3 150mm L/55 Type 39 naval gun 4 × 2 100mm L/40 Type 28 AA gun 8 × 2 Type 38 AA gun 22 × 1 12.5mm mg 4 × 2 610mm trainable torpedo tube
Aircraft carried:	1 floatplane
Aviation facilities:	1 × catapult, recovery crane

The Yŏng'il-class cruisers (Menghean: 영일급 순양함 / 迎日級巡洋艦, Yŏng'il-gŭb Sunyangham) were a group of six light cruisers built for the Imperial Menghean Navy during the Pan-Septentrion War. They were the last Menghean light cruisers commissioned during the conflict; two Sangha-class cruisers were laid down but never completed. Fast but lightly armored, they were designed to chase down destroyers and lead destroyer squadrons.

Development

The Boryŏng-class cruisers, five ships laid down between 1935 and 1937, were a modified version of the preceding Sunchang-class cruisers, with slightly thicker armor and a revised machinery arrangement. Though the Navy considered them an improvement, they were largely intended as an interim measure until a new, non-treaty-limited light cruiser class could be designed and laid down. Redesign efforts culminated in a light cruiser with nine 150mm guns in three triple turrets. Some proposals called for a larger or heavier ship, but these were initially turned down because the smaller vessel could be produced in existing shipyards on a faster schedule.

Description

Armament

The main battery of the Yŏng'il-class cruisers consisted of nine 15-centimeter (5.9-inch) guns in three triple turrets. Unlike the preceding Taean-class cruisers, which were first completed with 15cm triple turrets in an A-XY arrangement for retreating engagements, the Yŏng'ils had superfiring forward turrets, allowing them to allowing them to keep 2/3 of their firepower on the target when pursuing a destroyer. These guns were also an entirely new model, the 150mm L/55 Type 39 naval gun, with improved muzzle velocity and range. Menghean sources claim a rate of fire of 8 rounds per minute, though this would likely tire out the gun crews if sustained for too long, as loading and shell handling still relied heavily on manual labor.

Long-range AA armament consisted of eight 100mm L/40 dual-purpose guns in twin turrets with assisted shell ramming and ready racks. This weapon was already beginning to show its age by 1940, its poor range and accuracy hampering its ability to engage increasingly fast enemy planes. The ships were completed with eight twin mounts for the Type 38 anti-aircraft gun, as well as a large number of 12.5mm machine guns, which would be replaced with 20mm autocannons by the middle of 1942. Some early proposals called for the 150mm guns to be given anti-aircraft capability, but by 1939 most major navies including the IMN had concluded that 6-inch guns lacked the necessary traverse speed to be useful in the anti-air role.

The Yŏng'ils did come with a powerful torpedo armament, carrying four twin 610mm launchers for the Type 38 torpedo - a license-produced version of the Dayashinese "long lance". No on-board reloads were carried. Firing angles for these launchers were actually very good, compared to the rearward-only arcs on most Dayashinese cruisers, but the twin launchers were said to have experienced reliability problems in Menghean service.

Anti-submarine sensors consisted of a sonar and hydrophone room in the bow and a battery of depth charge racks and depth charge launchers on the stern. A total of 132 additional stored depth charges could be carried in the ships' initial configuration. The single floatplane, mounted on a catapult behind the #2 funnel, could be used to scout for surfaced submarines during long-range patrols, and could be fitted with depth-charge bombs of its own. Although the Yusin Type 40 mono-wing floatplane was already in service by this time, the IMN continued to use the older Namtong Type 36 on Yŏng'ils until late in the war, as Type 40 production was mainly directed to heavy cruisers and battleships.

Protection

<imgur thumb="yes" w="400" comment="Cross-section of the cruiser Yŏng'il showing armor thicknesses at various locations. Note that the magazines are protected by an internal box rather than an external belt.">BNCdk5R.png</imgur> As on preceding Menghean light cruisers, the armor scheme was relatively thin, and was mainly intended to provide protection against the gun calibers found on destroyers and light cruisers. The 75mm armor belt running along the outside of the ships only covered the turbine and boiler spaces, which extended well above the waterline. The magazines, by contrast, were covered by an internal 75mm armored box to save weight. Deck armor was 35mm thick over the engines and 50mm thick over the magazine spaces. The barbettes were 75mm thick, and the turret faces 100mm thick. Menghean sources claim that this scheme resulted in an immunity zone of 8,000 to 20,000 meters against early-war 6-inch shells, though it remained vulnerable to 8-inch or larger projectiles.

Torpedo protection was very light, a failing shared with the Boryŏng and Sunchang classes. The ships had a double hull with a small air compartment outside the fuel tanks, and the fuel tanks were separated from the boilers by a 20mm soft steel bulkhead. Yet there were no reinforced torpedo bulkheads in place, and the ships would have to rely entirely on internal compartmentalization to contain flooding.

Propulsion

Steam power came from eight oil-burning water-tube boilers under two trunked funnels. The four turbines they drove could produce a combined output of 100,000 shaft horsepower, for a top speed of 35.4 knots at normal load. While slower than some of the latest destroyers, this was nevertheless impressive, and it came as a slight improvement over their predecessors. Cruise range was 4,000 nautical miles at 15 knots, enough to support open-ocean raiding operations after the fall of Innominada.

Like the Boryŏngs, these cruisers had alternating boiler and turbine spaces, so that no single shell, bomb, or torpedo hit could completely immobilize the ship. The individual machinery units were separated by both transverse and centerline lengthwise bulkheads to further contain flooding, though the centerline bulkhead meant that flooding would be concentrated on one side, producing a list. The stabilization gyroscopes were located inside the aft magazine box, and the steering machinery room was not armored.

Ships in the class

<imgur thumb="yes" w="400" comment="Light Cruiser Hyangyang as she appeared at the Battle of Sunjuman. Note the heavy AA armament and late-war paint scheme.">ji5yvEq.png</imgur> A total of six Yŏng'il-class cruisers were completed before the end of the war, making them the last Menghean light cruiser class to see service before 1945. Their successors, the Sangha class, saw two ships laid down, but both were scrapped in 1943 to feed the Army's urgent demand for steel. Three Yŏng'il class cruisers survived the war, two of them in serviceable condition, and all were scrapped during the 1950s.

The Yŏng'il class ships were intended as multipurpose light cruisers, which could screen for larger fleets or command destroyer squadrons. As the war progressed and the IMN was pushed onto the defensive, they received heavy anti-aircraft refits. By 1945, all surviving ships had been refitted to carry 10 twin Type 38 anti-aircraft guns and around 31 single 20mm anti-air autocannons, with the exact number of the latter varying from ship to ship. These refits involved the replacement of the floatplane catapult with a deckhouse structure which contained additional crew space and housed a control room for the newly added ship's radar. This was a simple air-search unit which returned the target's distance and bearing, but its poor resolution and inability to handle large numbers of targets limited its usefulness.

Two Yŏng'il class cruisers, the Hyangyang and the Sujŏ, sank at the Battle of Sunjuman while leading a formation of destroyers and other light craft out of Sunju bay. This was the last naval engagement of the Pan-Septentrion War in which multiple Menghean warships were sunk on the same day. Hyangyang was badly damaged by dive bombers, leading her commander to attempt to beach the ship in shallow water so that she could be used as a coastal AA platform. She was struck by a torpedo during her approach and began taking on water more rapidly, eventually settling onto the muddy bottom with only her turrets, her superstructure, and part of her quarterdeck above the surface. The rusting wreck, now overgrown with vegetation, is still visible 800 meters out from shore. Sujŏ sank in deeper water further south; the Menghean government later considered raising and scrapping her wreck, which posed a danger to deep-hulled ships, but eventually decided to leave it in place with a hazard buoy nearby.

Name	Name (Stuart-Lavender)	Mengja	Laid down	Commissioned	Fate
Yŏng'il	Yohng Il	迎日	1938	1940	Damaged during the Naval Battle of Baumburg but repaired. Surrendered in Gyŏngsan, scrapped in 1954.
Jangwŏn	Chang Won	長垣	1938	1941	Sunk in a surface engagement off the coast of Khalistan on 3 February 1943.
Hyangyang	Hyang Yang	向陽	1939	1941	Sunk by Allied carrier aircraft at the Battle of Sunjuman on September 17th, 1945. Wreck is partially above the surface and visible from shore.
Ryŏngtae	Lyohng Thai	靈台	1939	1941	Severely damaged by Allied aircraft while escorting a convoy from Khalistan in 1943. In drydock at Anchŏn under intermittent repair work until the end of the war. Scrapped in place in 1949.
Manbok	Man Pok	萬福	1940	1942	Escaped the Battle of Sunjuman with moderate damage. Scrapped in 1953.
Sujŏ	Soo Choh	睢宁	1940	1943	Sunk by Allied carrier aircraft at the Battle of Sunjuman on September 17th, 1945.