Sibiwŏl Hyŏgmyŏng class aircraft carrier

File:Sibiwol Hyogmyong.png Sibiwŏl Hyŏgmyŏng while empty (note “SH” lettering on landing strip)
Class overview
Name:	Sibiwŏl Hyŏgmyŏng class
Builders:	Kimhae Naval Shipyard, Donggyong
Operators:	Menghe
Preceded by:	Sinbukgang-class aircraft carrier
Built:	1992-present
In service:	2006-present
Planned:	3
Building:	1
Completed:	2
Active:	2
General characteristics
Type:	fleet carrier
Displacement:	57,000 tonnes fully loaded
Length:	274.5 m at waterline, full load 302.2 m overall
Beam:	37 m at waterline 75.6 m at flight deck
Draught:	10.4 m to keel, full load 11.2 m including sonar bulge
Propulsion:	Nuclear marine propulsion 2 × Samsan ARK-4 pressurized water reactors 4 × steam turbine, 160,000 shp total 4 shafts
Speed:	30 knots
Range:	theoretically unlimited
Endurance:	~60 days (food and other supplies)
Complement:	1,890 ship’s crew 920 air wing personnel 2,810 total
Sensors and processing systems:	MTH-12000 3D search radar ATH-40 TACAN
Electronic warfare & decoys:	4x JT-500 ESM/ECM
Armament:	4 × 1 "Subibyŏng" gun/missile CIWS 2 × 1 RBDJ-34/8 ASW rocket projector 6 × 1 12.7mm HMG
Aircraft carried:	48 aircraft
Aviation facilities:	CATOBAR flight deck 3 catapults 4 arrestor wires

This article is about an aircraft carrier class in the Menghean Navy. For the 1987 coup serving as its namesake, see Decembrist Revolution

The Sibiwŏl Hyŏgmyŏng (Menghean: 십이월 혁명급 항공모함, Sibiwŏl Hyŏgmyŏng-gŭb Hanggongmuhang), sometimes abbreviated Sibiwŏl-class, are a series of three nuclear-powered, medium-sized fleet aircraft carriers built in the Socialist Republic of Menghe. The first ship in the class is named for the Decembrist Revolution, a coup in which Major-General Choe Sŭng-min overthrew the Democratic Republic of Menghe and established today's Socialist regime. They are the only nuclear-powered surface warships in the Menghean Navy, and the largest warships ever operated by Menghe.

Development

Work that developed into the Sibiwŏl class predated the Decembrist Revolution itself. As far back as 1982, the same year the second Sinbukgang-class aircraft carrier was commissioned, the Menghe People’s Navy was already considering proposals for a nuclear-powered aircraft carrier class to succeed it. The final design was to displace 80,000 tonnes at full load, making it twice the mass of its predecessors and considerably larger than the actual Sibiwŏl class. Some early proposals suggested the use of a ski-ramp at the forward end of the flight deck, but in the end the design was modified to use a total of four steam catapults, compared to two on the Sinbukgang class.

In 1984 the Navy laid down the keel of the first ship, still unnamed, at the Kimhae Naval Shipyard in Donggyong. Construction never proceeded beyond the early stages, however, as budget cuts and design revisions prevented further work. After Choe Sŭng-min seized power in 1987, the keel and early structure remained neglected in drydock for two more years as the government focused on reconstruction in the civilian economy. In 1990 the Menghean government formed a commission to assess the feasibility of completing the carrier to a modified design. Preliminary inspections, however, found that serious structural faults had emerged in the existing keel and hull structure during construction or suspension. Rather than risk modifying the hull, which was already seen as too large for Menghean needs, the government instead decided to scrap what was left and start anew with a program for two smaller nuclear-powered carriers.

This subsequent carrier design is what later developed into the Sibiwŏl Hyŏgmyŏng class. It retained a similar general layout to the old design, but was some 20,000 tonnes lighter, with three catapults instead of four, two elevators instead of three, and a reduced aircraft carrying capacity. These changes reflected the shift toward a military doctrine focused on expeditionary warfare, allowing the Menghean People's Navy to deploy a more flexible and mobile carrier force around the world in response to smaller conflicts rather than meeting larger carrier-battlegroups head-on. The designers briefly considered reverting to a ski-jump layout for the sake of simplicity, but eventually decided to retain the CATOBAR launch and recovery system to allow aircraft to take off with heavy fuel and weapons loads.

Design

Propulsion

The Sibiwŏl Hyŏgmyŏng and its sister ships are the first nuclear-powered warships to serve in the Menghean Navy. Each ship is powered by two PWR reactors, which are kept in isolated compartments. The steam from these reactors is combined to drive four 40,000-shp steam turbines, each of which is connected to a single propeller shaft. Theoretically, this propulsion system gives the carriers an unlimited cruising range, but in practice range is still limited due to the need to take on other supplies and allow the crew to rest ashore. In practice, however, it does allow the ships to operate continuously at their top speed of 30 knots without raising fuel concerns, permitting continuous flight deck operations while sailing into the wind.

The reactors are designed to operate continuously for up to 20 years before needing a mid-life refueling, and it is predicted that the carriers will be kept in service for two refueling cycles each. Accordingly, the Sibiwŏl Hyŏgmyŏng is scheduled to begin a refueling and refit cycle in 2026, although there has been some talk about moving this date a few years earlier.

Aircraft Handling Facilities

File:Sibiwol Hyogmyong hangars.png

Top-view showing aircraft storage on the flight deck and inside the hangar. The aircraft on the catapults and landing circles are for display and are not included in the count.

In its current configuration, the Sibiwŏl Hyŏgmyŏng supports a wing of 48 aircraft, including fighters, tiltrotors, AEW aircraft, and helicopters. This represents slightly over half the air wing of a larger nuclear supercarrier. In normal operations, these aircraft are split about half-and-half between the flight deck and the internal hangar. Transport between the hangar and the flight deck is accomplished by means of two large elevators, which are used as parking space when all aircraft are aboard. There are also three smaller elevators used to bring up munitions from the ship’s magazine. Rather than running directly downward, these have a transfer point along their routes, preventing debris, sparks, or flame from triggering a magazine explosion if the ship is damaged.

The carrier launches and recovers aircraft by means of a CATOBAR arrangement. It has steam catapults, two forward and one amidships, all of which have jet exhaust deflectors. When all aircraft in the carrier air wing are embarked, two of the three catapults remain unobstructed and usable, although one of these two occupies the landing strip and cannot be used while recovering aircraft. Additionally, while fighters are parked along the bow, D-4 aircraft must be launched from the amidships catapult, as their wingspan extends beyond the safe area boundary around the forward catapult. Recovery of fixed-wing aircraft is assisted by four arrestor wires running across the angled flight deck. There are also three circles painted on the flight deck to assist in launching and recovering helicopters and tiltrotors, though these aircraft can also take off and land from other areas of the flight deck as needed.

The internal hangar carries about half of the carrier’s air wing depending on configuration. It has access to four munitions elevators running down into the ship’s magazine; when not in use, these are shielded behind metal doors to prevent any fire or debris from reaching the magazines if the ship is damaged. One of its ingenious features is a pair of turntable sections alongside the aircraft elevators. These allow air crews to easily and safely rotate aircraft which have been pulled forward from storage alongside, allowing them to be loaded tail-first onto the elevator. In the event of an emergency, damage control teams can remotely extend a heavy flame-retardant curtain across the center of the hangar, containing any fires in one hangar and allowing the other hangar to continue operations if necessary.

Like many aircraft carriers of its time period, the Sibiwŏl Hyŏgmyŏng employs an optical landing system to help guide pilots down onto the landing section. The light array is located to the port side of the landing runway, and is paired with a radome which can track the aircraft’s approach more precisely if needed. Fresnel lenses and fiber-optic source lights to produce a sharper display that is visible from further away, allowing landing aircraft to adjust their approach from a greater distance. The optical landing system allows the carrier to guide aircraft to a landing even under conditions of total radar and radio silence, which would be normal during wartime carrier operations.

Defensive Armament

Subibyŏng CIWS

Each ship of the Sibiwŏl class is armed with four “Subibyŏng” missile-and-gun CIWS mounts, one at each corner of the flight deck. This permits full 360-degree coverage of the ship’s irregular shape without requiring guns to fire over the deck itself.

The Subibyŏng consists of two six-barreled 30mm autocannons on a central mount. Targeting is accomplished by means of a radar dish and electro-optical camera on top of the mount itself. The guns can generate a combined rate of fire of 8,000 rounds per minute, and have an effective range of 4,000 meters. Each mount has 4,000 stored rounds below the deck. Like other Menghean CIWS systems, the rotary guns are electrically spun, and can be fired at a reduced ROF of 300 rounds per minute each when targeting light boats.

The system’s guns are supported by eight YDG-61 IIR-guided SAMs in quad mounts on arms to either side. The YDG-61 has a maximum range of 16 kilometers, extending the ship’s defensive fire further out to the horizon. It is also fire-and-forget, allowing each mount to move on to a new target or switch to gun targeting once it has fired a missile. An additional 24 missiles are stored vertically below the deck in their four-cell units; once the launcher has exhausted its eight-missile initial load, it can eject the empty canisters overboard, rotate to a neutral angle, and load new missile canisters onto the launch rails.

RBDJ-34-8

Main article: RBDJ-34/8

For anti-submarine defense, the Sibiwŏl-class carriers are armed with two RBDJ-34/8 depth charge projector systems. These are mounted on either side of the stern, allowing coverage of the ship’s rear 270-degree arc. Each mount consists of eight 340mm rocket tubes, which can be automatically reloaded from below the deck when the launcher is tilted to vertical. The system can fire projectiles out to a maximum range of 1200 meters.

A total of 48 rounds can be carried beneath each launcher to allow multiple reloading. In practice, the rocket loadout on the aircraft carriers’ RBDJ-34/8 systems is composed primarily of R-34ŎD softkill sonar jamming projectiles and R-34DŎ hardkill torpedo countermeasures.

All ships of the class also carry two trailing torpedo decoys, which can be reeled out on a cable behind the ship.

Aircraft

Strike Airgroup

During the carriers’ construction, Navy high command intended for the Sibiwŏl Hyŏgmyŏng to serve as an expeditionary force which could deploy overseas with the support of other regional powers to intervene in local conflicts. As such, its initial carrier air wing reflected a sea-to-land strike role. Its combat aircraft were a mix of single-seat fighters and twin-seat tactical bombers, both based on the Sŏngrim SL-8 heavy multirole. These were joined by a number of DeSilvo D-4 support aircraft, for radio and radar jamming, AEW, large-area anti-submarine warfare, and carrier onboard delivery.

Unfortunately, the first ship in the class was commissioned just as the Menghean Navy was pivoting away from expeditionary warfare, meaning that much of the initial work configuring the ships’ air group had to be revised. For some time, the Navy retained the original layout in a revised form, with additional AEW aircraft in place of the jamming D-4s and the tactical bombers repurposed to deliver anti-ship missiles rather than bombs.

Support Airgroup

Efforts to repurpose the old air wing for parity warfare were only a temporary measure, however. In 2013, the Sibiwŏl Hyŏgmyŏng went to sea with a revised carrier air wing. The new carrier air wing renders permanent the temporary practice of replacing jamming aircraft with AEW platforms, bringing the total for the latter up to four. It also replaces most of the D-4 ASW and COD aircraft with D-8 tiltrotors, which are more compact in stored form and can take off vertically but retain adequate range and loiter time. The reduction in deck area devoted to support aircraft, and the use of elevators as parking space, allowed for an additional eight SL-8 multirole aircraft. The air wing totals were thus revised to:

• 32x SL-8MK or SL-8MK2 multirole aircraft
• 4x D-4Ch AEW&C aircraft
• 6x D-8A ASW tiltrotor
• 4x GHZ-28B ASW helicopter
• 2x GHZ-28D rescue helicopter

In the last few years, there have been some reports of Sibiwŏl-class carriers taking on supplies, mail, or personnel via one or more D-10 tiltrotors flying in from shore or from another ship. This initially led to speculation that the air wing had been modified, with two D-10s and four D-8As rather than six D-8As. A 2015 documentary sponsored by the ISN, however, stated that these D-10s were actually not part of the ship’s air wing, and had flown in from shore bases or other ships as an improvised means of extending endurance or delivering urgently needed small parts. In regular operation, the Sibiwŏl-class carriers still rely on port facilities and support ships for most of their supply needs.

New subclass

The third ship of the class, launched in 2014 but still in fitting-out, was built on the same hull as the previous two ships but appears to incorporate a number of modifications and improvements. The most noticeable change concerns the location of the island, which was moved further back to leave more room for aircraft leaving the rear elevator. In addition, all three steam catapults were replaced with electromagnetic catapults that allow a smoother acceleration to reduce strain on pilots and aircraft. Other changes included the revision of the defensive armament, with space for a 10-cell shallow-depth VLS array off the port side for longer-range missile defense. The composition of the air wing is not believed to have undergone any major changes.

Role

Though originally intended as an expeditionary warfare platform, the Sibiwŏl Hyŏgmyŏng and her sister ships now play a more cautious fleet support role. In the event of a local counter-offensive war, their air groups would be responsible for extending fighter cover further outward from the mainland, thus shielding surface fleets and submarines from enemy strike aircraft and ASW patrols. Although the SL-8MK2 is capable of carrying anti-ship missiles, most serious anti-shipping missions would come from land-based airfields. The air group is also relatively light on ASW aircraft, and these are mainly geared toward self-defense of the battlegroup. Area ASW missions would be left primarily to coastal maritime patrol aircraft and lighter vessels such as the Changzha-class aircraft carriers.

Ships in the Class

• Sibiwŏl Hyŏgmyŏng (Decembrist Revolution): laid down 1992, launched 1999, commissioned 2006
• Joguk-ŭl Gaebalhae ("Build up the Nation"): laid down 2000, launched 2006, commissioned 2013
• Unnamed hull: laid down 2007, launched 2014, undergoing fitting-out

After the launching of the ISS Um-eul Baucheone's hull in 2010, the upper leadership of the Menghean Navy has maintained that it was only interested in building three aircraft carriers - seen as the minimum needed to ensure that one is on patrol at any given time. In August 2016, however, it was reported that a fourth carrier, as yet unnamed, was laid down in the large drydock which had been used to build ISS Um-eul Baucheone. Satellite imagery of the port at Masad has confirmed that a large keel and bracing supports similar to those in the early construction of the other three carriers are in place. Classified documents leaked the following October suggest that the ISN plans to expand the carrier fleet to five or six ships within the next fifteen years. The ISN has thus far denied these allegations, though the large drydock at the Masad-Meng Special Naval Shipyard remains off-limits to non-military personnel.

See also

• Sinbukgang-class aircraft carrier
• Dolsando-class helicopter carrier
• Haeju-class destroyer
• Jŏngdŏk-class frigate