YDH-23

YDH-23 "Yusŏng"
A YDH-23G carried under the wing of a Yŏng'an Y-4 bomber.
Type	Long-range anti-ship missile
Place of origin	Democratic People's Republic of Menghe
Service history
In service	1982-present
Production history
Manufacturer	Institute 55
Specifications
Weight	3,952 kg
Length	10.54 m
Height	2.2 m
Diameter	0.9 m
Warhead	700 kg warhead
Detonation mechanism	Contact fuse
Engine	ZhRD S5.33 liquid-fuel rocket
Wingspan	2.4 m
Propellant	TG-02 / AK-20F
Operational range	280 km (YDH-23G) 500 km (YDH-23D)
Flight altitude	25-30 km
Speed	Mach 3-4
Guidance system	inertial guidance, terminal active radar homing
Launch platform	Yŏng'an Y-4 Songrim SR-6HG Songrim SR-9HG Chŏndong-class destroyer JYDH-23 TEL

The YDH-23 Formal designation: 23식 대함 유도탄 / 二三式對艦誘導彈, i-sam-sik daeham yudotan, "Type 23 anti-ship missile;" Short designation 유대함-23 Yudaeham-isam "YDH-23") is a heavy, long-range anti-ship missile built in Menghe as a license-produced derivative of the Letnian KSR-5. It also served as the basis for land-attack derivatives bearing the designation YGJ-23. Improved versions of the missile remain in service with the Menghean Navy. It has been promoted under the name Yusŏng, or "Falling Star."

Trajectory

The YDH-23 approaches its target on a quasi-ballistic trajectory, climbing to a cruising altitude of 25-30 kilometers after launch in order to minimize drag and maximize search range. At this stage, it proceeds toward the target's last reported location on the basis of inertial guidance, with mid-course updates if the targeted fleet changes course.

Once the missile picks up the target on its own radar, it proceeds to correct its course independently, though it remains at a level altitude. Once the slant angle to the target reaches 60 degrees from the horizontal, the YDH-23 enters a steep, high-speed dive. The contact fuse is designed with a slight delay, so that the missile will detonate inside the hangar of an aircraft carrier or inside the machinery rooms of a destroyer or frigate; even if the warhead itself fails, the missile impacts the target with some 2,000 megajoules of kinetic energy, equivalent to 478 kilograms of TNT.

At the time of its introduction, the YDH-23's high approach altitude was outside the range of many legacy SAMs, and its steep approach angle was above the angle that some legacy radars could track. The introduction of the Dayashinese Suijin system in the 1990s greatly improved air defense against high-level targets, turning the YDH-23's approach path into a liability. During the late 1990s, some efforts were made to develop a sea-skimming mode for the YDH-23, but low-level drag sharply reduced speed and range, and the project was abandoned in favor of newer AShMs.

Variants

YDH-23G:

Initial production version introduced in 1982. It was a direct copy of the KSR-5.

YDH-23GS:

Variant with an anti-radiation seeker, based on the KSR-5P.

YDH-23JG:

Surface-launched variant introduced in 1984. It featured folding wings and tail surfaces, allowing it to be fired from a cylindrical container. Solid-fuel boosters were added under the tail to propel it into the air, and the guidance system was modified to support initial arming and fin-unfolding after stationary launch.

YDH-23N:

An air-launched variant incorporating the folding wings of the YDH-23JG. Its more compact size allowed it to be carried on the specially reinforced pylons of the Songrim SR-6HG. Introduced in small numbers in 1985.

YGJ-23G:

Air-launched nuclear standoff weapon tested in 1986. It relied on inertial guidance over its entire flight course, and had a circular error probable of 2-3 kilometers. Efforts to miniaturize the nuclear warhead encountered delays, and fewer than six were built before Menghe terminated its nuclear program.

YDH-23D:

YDH-23G modified to carry a nuclear warhead, while retaining the anti-shipping mode. One was built for testing, but no warhead was fitted.

YDH-23R1:

Comprehensive upgrade which entered service in 2009. It featured a more efficient rocket for a 500-kilometer range, an improved seeker with home-on-jam capability, an under-slung electro-optical lens for redundant guidance, and a new prefragmented warhead in place of the earlier shaped charge. It could also receive initial targeting cues and mid-course updates from military satellites.

YDH-23R2:

Folding-wing variant of the YDH-23R1 for use on medium strike aircraft.

YDH-23JR:

Land- and Ship-launched variant of the YDH-23R1.

YGJ-23N:

Conventional ground-attack variant introduced in 2011. It relies on Constellation satellite guidance and electro-optical reference image matching, for a CEP of 5 meters. Its warhead is replaced by a modified JP-1000 ground-penetrating bomb, and it is mainly intended for use against deep bunkers and fortifications, with a Mach 4 dive providing additional momentum on impact.

Old content

The YDH-23 is a solid-fueled, two-stage missile with a diameter of 58 centimeters. Its control surfaces are located on the tail and driven by mechanisms around the engine nozzle, but the guidance unit itself is forward of the fuel section, linked to the tail by a covered “spine” that runs along the top. Terminal guidance relies on active radar homing, with a secondary home-on-jam capability for increased resistance to certain countermeasures. En-route guidance is provided by a combination of Satellite Navigation and inertial guidance, and the missile can be datalinked back to the launch aircraft or a partnered “watcher” to allow course correction if the target fleet moves.

Sandwiched between the guidance unit and the solid fuel is a 750-kilogram conventional warhead. This warhead incorporates a pre-fragmented outer shell to increase damage to ship systems after impact, and the missile’s own weight and momentum causes extensive damage by itself. On the diving flight path (see below), the missile is programmed to detonate after a slightly longer delay, allowing it to penetrate into the depths of a large ship and explode near the keel, engines, or magazines to increase the risk of critical damage. A nuclear-armed anti-ship variant was proposed during the 1980s, as was a nuclear-armed land attack variant, but neither entered service prior to the new Menghean regime’s nuclear disarmament.

Flight Paths

On its typical anti-ship flight profile, the YDH-23 gradually climbs to an altitude of about 30,000 meters and cruises toward a target area set by inertial navigation, satellite navigation, or datalinked manned aircraft. At this stage of the flight course, it reaches a top speed of somewhere between Mach 3.3 and Mach 4, depending on the source. As the missile nears the enemy fleet and switches over to radar guidance, it climbs again to over 40,000 meters, then executes a maneuvering dive on the target. At this stage in the flight path, it nears Mach 5, making it extremely difficult to intercept. Maximum attainable range with this flight path is cited as 500-600 kilometers, allowing the launch aircraft to remain outside the range of ship-based SAMs and limiting exposure to patrolling fighters.

A problem with this high flight path, however, is that it exposes the missile to long-range surface-to-air missiles during its high-altitude approach. In order to mitigate this problem, the designers added a secondary “sea-skimming mode” in which the missile gradually descends to an altitude of 10 meters after launch. This means that against most surface warships, the missile will only cross the horizon at a distance of less than 30 kilometers. Higher air resistance at this altitude, however, means that the missile’s range is reduced to about 200 kilometers, and its terminal speed to a little over Mach 2.

KST-23

A land-attack variant, the KST-23, was introduced in 2008 in response to the perceived danger of war with Maverica or Firmador. Though it uses the same missile body, the KST-23 replaces the radar seeker and prefragmented warhead with a single 1000-kilogram ground-penetrating munition based on the KST-1000 bomb family but with higher-strength walls and a slightly reduced explosive content. The resulting weapon, designated YDH-23DJ (대지하엄폐호, Dae-Jihaŏmpyeho, anti-bunker), is a standoff ground penetrating munition for use against high-value hardened land targets such as command bunkers and missile silos. Using the same diving profile as the anti-ship variant, it can penetrate much deeper than a gravity bomb, but due to high costs and niche usefulness, relatively few were produced.

Operators

Menghe

See also

• YDH-28
• List of Menghean missiles