Yobu-class destroyer
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| Class overview | |
|---|---|
| Name: | Yobu class |
| Builders: | Gyŏngsan Songsu-do Naval Yard |
| Operators: | Menghe |
| Preceded by: | none |
| Built: | 1974-1992 |
| In service: | 1978-present |
| Planned: | 17 |
| Completed: | 14 |
| Cancelled: | 3 |
| General characteristics Yobu-class, as built | |
| Type: | guided missile destroyer |
| Displacement: |
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| Length: |
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| Beam: | 16.1 m |
| Draft: | 4.58 m |
| Propulsion: |
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| Speed: | 32 knots |
| Range: | 5,500 nautical miles (10,000 km) |
| Complement: | 297 |
| Armament: | |
The Yobu-class destroyers (Menghean: 요부급 주력 호위함 / 饒富級主力護衛艦 Yobu-gŭb Juryŏk Howiham) are a class of warship built in the Democratic People's Republic of Menghe between 1974 and 1992. They are generally known in the West as guided missile destroyers, but in Menghe they are officially classified as "main-force guard ships." Though similar in capabilities to the Letnian Kashin-class destroyers, the Yobu-class are an indigenous Menghean design, albeit one armed with licensed Letnian weaponry.
A total of 14 hulls were completed between 1978 and 1992, out of 17 ships ordered. Hulls 8 through 14, starting with HJ Hyŏngnam, were built to a modified design with rearranged armament and a stretched stern, and are sometimes considered a separate ship class. The 14th ship, Maepo, was laid down as part of the Hyŏngnam subclass but completed with a different missile armament and sensor arrangement, and is sometimes considered a unique ship class.
Development
During the postwar emergency shipbuilding program, the DPRM laid down a large number of Taepung-class deestroyers and Nunbora-class destroyers. Simple designs optimized for mass production from Menghe's technologically delayed shipbuilding sector, these warships were oriented toward surface warfare, and relied entirely on dual-purpose guns and small-caliber AA guns for their anti-aircraft armament. This left them seriously vulnerable to enemy jet aircraft carrying anti-ship missiles.
Menghean engineers responded by developing a speial-purpose warship with more advanced anti-air and anti-submarine armament. To achieve the required characteristics on a small hull, they omitted anti-ship missiles, and reduced the gun armament to two 76mm twin turrets aft. The resulting design was also larger and more expensive than Menghe's contemporary destroyer classes. Together, these characteristics made it unsuitable as a full-on replacement. As such, the type was classified as a "main-force guard ship" (juryŏk howiham) tasked with escorting formations of destroyers (guchugham) that specialized in anti-surface warfare. This duality of destroyer types would persist in Menghean ship design philosophy until the middle of the 1990s.
The final blueprint was designated Plan 567. Its armament, radar, and sonar systems were all licensed from Letnia, but the hull was a domestic design, and it went through several redesign iterations. The first ship in the class, HJ Yobu, was laid down on June 24th, 1974 in Drydock 1 of the Songsu-do naval base. Despite an initial requirement to keep length under 135 meters, the class ended up being too large for Songsu-do's small destroyer drydocks, and they were built in the cruiser-size drydock instead.
Design
In terms of their overall capabilities, the Yobu-class destroyers are similar to Letnia's Kashin-class destroyers, and they use many of the same weapon systems and sensors. Nevertheless, the Yobu-class can be easily distinguished by their aft superfiring guns, their single funnel with "solid" radar mast attached, and their wide bridge structure. Their 533mm torpedo armament is also split between two four-tube launchers, one on either side.
The ships' main anti-air armament consists of two twin-arm launchers for the YDG-32 surface-to-air missile, a licensed copy of the Letnian S-125 Neva/Pechora. The twin-arm launchers are also licensed copies of the Letnian ZIF-101 system, with 16 reload missiles per launcher in eight-missile carousels. For close-range air defense, the Yobu-class carries four AK-630 CIWS turrets, with each pair controlled by a single "Vympel" targeting radar with manual backup sight. Additionally, the ships' 76mm AK-726 turrets are dual-purpose weapons which can engage aircraft and missiles as well as surface targets. Air-search radar consists of one "Kliver" 2D search radar and one "Angara-A" search radar with height-finding capability.
Anti-submarine armament consists of two RBU-6000 rocket projectors forward, which can also fire torpedo decoy countermeasure rounds. The 533mm torpedo tubes on either side can launch both wireless homing and wire-guided torpedoes. The main sonar module, license-produced from Letnia, contains "Titan" and "Vychegda" sonar antennas, and can retract almost fully inside of the hull to aid in drydocking and shallow-water berthing. The original seveen Yobu-class ships lack variable-depth sonar.
The ships' powerplant is domestic in design, and consists of four high-pressure boilers connected to two steam turbines. Both the boilers and turbines use a domestic Menghean design. At full power, the ships can reportedly reach a top speed of 33 knots, but they lack the fast acceleration of gas-turbine ships. Exhaust from the turbines is vented through a single trunked funnel.
Hyŏngnam subclass
The original procurement plan called for twelve Yobu-class destroyers, to be laid down at a rate of one per year. As time passed, however, some shortcomings of the Yobu-class became apparent, most notably its lack of helicopter facilities. Initially, this was considered an acceptable tradeoff, as the Menghean People's Navy mainly operated close to shore; but by the middle of the 1970s, the Menghean leadership had growing ambitions for long-range patrol capability. In 1975, the DPRM began work on a tandem-rotor helicopter for shipborne use, later designated GH-28. With the type nearing operational readiness by 1980, the Navy leadership ordered a redesign of future Yobu-class hulls to support a helicopter for prolonged at-sea operations. Navy leaders also demanded the addition of a variable-depth sonar, a feature absent on the existing hulls.
In mid-1979, the remaining 5 planned Yobu-class ships were cancelled and replaced by 5 units the new guard ship design. This design, designated Plan 5672, added a variable-depth sonar under the quarterdeck, with a helicopter landing pad and hangar forward of it. In keeping with Letnian ship design practices, the hangar was recessed one deck, with a ramp leading into it and a sliding roof on top. These changes required extending the quarterdeck aft by 1.5 meters.
To make room for the hangar, the aft twin 76mm turrets had to be deleted. As a replacement, a single twin 76mm turret was added on the foredeck in place of the RBU-6000 anti-submarine rocket launchers, which were instead mounted on either side of the hangar. The relocation of the 76mm turret's fire-control radar to a forward-facing position led to a thorough redesign of the bridge and lattice mast. Additional deckhouse structures were added to the aft superstructure, apparently as accommodations for displaced crew accommodations.
The first ship built to this revised design, Hyŏngnam, was laid down on February 9th, 1980, and completed on November 6th, 1983. Western intelligence sources classified the ship as a subclass of the Yobu type, though in Menghe it was regarded as a separate ship class entirely. The next five hulls, including Hyŏngnam, were laid down according to schedule, and at the end of 1984 the DPRM budgeted five more as part of an emergency plan to strengthen the Navy in response to escalating tensions surrounding Menghe's nuclear weapons program. Two of these additional ships were laid down, and the remaining three were cancelled in 1988 following the Decembrist Revolution.