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 |
|
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."
Design and development
The Democratic People's Republic of Menghe purchased an initial batch of Letnian KSR-5 missiles in 1982 to bolster the anti-shipping capabilites of the Menghean People's Navy Air Wing. Domestic production began the following year, based on a combination of blueprints and knock-down assembly kits.
While the Letnian missile was exclusively carried by the Tu-16 bomber, the DPRM devised a lengthy series of YDH-23 variants and derivatives, modifying the missile for land launch, sea launch, and launch from lighter attack aircraft. Some of these variants had folding wings to allow for more compact storage, an innovation not seen in Letnian service.
Following the Decembrist Revolution, intermittent work on improving the YDH-23 continued in the background. The YDH-23D came with a new seeker and a greatly extended maximum range, though by that time it faced competition from the lighter, faster YDH-27.
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:
- Proposed folding-wing variant of the YDH-23R1 for use on medium strike aircraft. Not produced in large numbers.
- 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.
