YDH-27

YDH-27 "Sinpung"
Side views of the YDH-27, including a cross-section.
Type	Supersonic anti-ship missile
Place of origin	Menghe
Service history
In service	2006-present
Production history
Manufacturer	Institute 57
Specifications
Weight	1,500 kg
Length	5.86 m
Diameter	52 cm
Warhead	200 kg warhead
Detonation mechanism	Contact fuse
Engine	dual-pulse solid-fuel rocket
Wingspan	88 cm
Operational range	400 km
Flight altitude	30-40 km
Speed	Mach 4-5
Guidance system	inertial guidance, terminal active radar homing
Launch platform	Yŏng'an Y-4 Songrim SR-6HG Songrim SR-9HG

The YDH-27 (Formal designation: 27식 대함 유도탄 / 二七式對艦誘導彈, i-chil-sik daeham yudotan, "Type 27 anti-ship missile;" Short designation 유대함-27 Yudaeham-ichil "YDH-27"), also publicized as Sinpung or "divine storm," is a high-supersonic anti-ship missile developed in Menghe for the Menghean Navy. It is designed to supplement and replace the YDH-23 Yusŏng.

Development

Although the YDH-23 performed well in the bomber-launched role, its size and weight limited its usefulness. The YDH-23N variant was integrated successfully onto the Songrim SR-6HG bomber, but the two-missile load came out to a mass of 8,000 kilograms, the SR-6's entire useful payload. Long takeoff rolls, poor in-flight performance, and a short strike range resulted. Even this solution required integrating folding wings and tail surfaces onto the YDH-23, as it sat too close to the fuselage to be carried in its "G" configuration.

Institute 57, Menghe's main supersonic missile development bureau, expressed concern with these problems, and viewed the YDH-23N as an interim solution while a lighter missile could be developed. The political turmoil and economic sanctions of the Ryŏ Ho-jun period hindered development, and Menghe's domestic missile industry was still immature.

After the Decembrist Revolution, Institute 57 resumed work on its lightweight supersonic missile, but the new political climate produced different delays. Improving relations with Dayashina, Tír Glas, Sieuxerr, and Tyran reduced the pressure to develop an anti-carrier weapon, and the military budget stagnated even as the economy grew. Periodic tests were conducted throughout the 1990s and early 2000s, but the Ministry of National Defense provided only intermittent funding to the project, and it remained something of a back-burner effort for the design team. Flight tests were only conducted in 2000, and even then the Navy expressed little interest in buying the weapon.

This situation changed dramatically after the Ummayan Civil War, which led to an immediate worsening of Menghe's relations with Tyran, Innominada, and Maverica. Once again concerned about the risk of carrier incursions, the MoND ordered Institute 57 to reactivate the high-supersonic missile project. Twenty years of gradual progress had already produced a smoothly functioning prototype, which, after a new round of trials to check its reliability, was ordered into production as the YDH-27 in 2006.

Design

The YDH-27 "Sinpung" is a high-supersonic, long-range weapon, designed for use against grouped or isolated warships as part of a coordinated strike. Its engine consists of a dual-pulse solid-fuel rocket with a climb/acceleration stage and a descent/cruise stage, for a total range of 400-500 kilometers, depending on variant.

The missile's guidance pattern resembles that of the preceding YDH-23. After launch, it proceeds toward the target on a quasi-ballistic high-level trajectory, rising to a height of over 40,000 meters. As air resistance is much lighter at this altitude, range and speed are correspondingly increased. During the initial launch phase, the missile relies on inertial guidance, coupled with periodic updates received via a datalink above the rear end of the missile. During the descent phase, the YSH-27 activates its active radar seeker (or, in the case of the YDH-27D, its electro-optical camera) and guides itself onto the target autonomously. The radar seeker uses frequency hopping to improve its resistance to jamming, and final approach speed is close to Mach 5, making the missile very difficult to intercept in the terminal phase. The high-altitude approach does leave it open to interception by long-range ship-based SAMs, as it can be spotted over the horizon from hundreds of kilometers away, as opposed to a sea-skimming weapon appearing over the horizon with much less warning.

With a mass of just under 1,500 kilograms, the YDH-27 is relatively heavy, and impacts the target with high momentum. Yet it is still a little over a third of the weight of the YDH-23, giving the Navy greater flexibility in mounting it on different planes. A single Yŏng'an Y-4HR bomber can carry either two YDH-23 or six YDH-37 missiles, with the latter option offering greater saturation of enemy air defenses. The Songrim SR-6HG2 can carry up to two such missiles, and the Songrim SR-9HG can carry up to three, with both planes loaded to less than half their maximum payload for a greater range and more maneuverability. None of these planes require folding-wing variants of the missile, as the small tail surfaces carried at the diagonal do not extend far from the sides of the missile.

Unlike the YDH-23, which generated both land-launched and sea-launched variants, the Sinpung is exclusively produced in air-launched variants. At times, the Menghean Army has expressed interest in developing a land-attack variant guided by a terminal infrared seeker and the Constellation Satellite System, but no orders have been made as of 2018.

Variants

YDH-27G:

Initial naval version with active radar seeker, introduced in 2006.

YDH-27N:

Improved variant introduced in 2012. The updated guidance system conducts pseudo-random maneuvers during the terminal descent, making the missile harder to hit. Range was increased to 500 kilometers through the use of new propellant.

YDH-27D:

Variant of the YDH-27N with an electro-optical seeker in place of the active radar. A mixed salvo of radar-guided and IR-guided missiles would have greater resilience to jamming efforts.

See also

• YDH-23
• List of Menghean missiles