SY-56 Ho-u
| SY-56 Ho-u | |
|---|---|
 Side views and cross-section views of the SY-56 Ho-u | |
| Type | Submarine-launched cruise missile |
| Place of origin | Menghe |
| Service history | |
| In service | 2021-present |
| Production history | |
| Manufacturer | Navy Development Arsenal |
| Specifications | |
| Weight | 1,450 kg with booster |
| Length | 5.60 m (missile alone) 6.32 m (with booster) |
| Diameter | 52 cm |
| Warhead | 12× 100kg runway-cratering munition |
| Engine | Turbofan |
| Wingspan | 840 mm |
Operational range | 350 km |
| Speed | Mach 0.8 |
Guidance system | Inertial guidance, terminal contrast seeker |
Launch platform | Daedam-class submarine Chŏngsangŏri-class submarine |
The SY-56 Ho-u is a type of submarine-launched cruise missile developed in Menghe for the Menghean Navy. It is derived from the widely used YDH-28 anti-ship missile, and shares the same propulsion module and a similar wing structure, but pairs these with an entirely different seeker and paylod section with a shortened body in between. Instead of a unitary warhead, it carries twelve runway-cratering munitions which can be individually released at regular intervals.
Development
The SY-56 Ho-u was specifically developed to conduct surprise strikes on EC airbases in Khalistan and Portcullia. During the second half of the 2010s, Menghe developed a number of cruise missiles capable of striking these targets from bases in the Republic of Innominada, but the subsonic speed of these missiles would give the defending forces up to 45 minutes to ready their defenses and scramble fighter aircraft. A submerged diesel-electric submarine operating close to a coastal naval base, however, could launch missiles from a closer distance, disabling airfields within 5-10 minutes of launch and thus trapping more aircraft on the ground.
Initially, the Menghean Navy sought to achieve this by using a modified version of the YDH-28 anti-ship missile with a new warhead. During development, the missile was treated as a branch of the SY-28 cruise missile project, and a mockup was exhibited to the public in 2019 under the designation SY-28JD. The increased volume and mass of the new warhead, however, required substantial changes to the missile's fuselage, and in the end the SY-56 entered service under an entirely new designation.
Operation
The SY-56 relies entirely on inertial navigation for its approach to the target, and possesses no CSNS guidance mode. This reflects an expectation that its likely attack sites would be protected by intense CSNS jamming, as SY-56 strikes would precede follow-up attacks on jamming installations. Fully inertial guidance does, however, mean that the launching submarine must ascend to periscope depth and confirm its coordinates via high-frequency direction finding or CSNS positioning and pass that information to the missiles before launching.
Once the missiles near their target area, they activate their forward electro-optical imaging sensors. These reference the terrain ahead with uploaded map data to correct for any drift during the initial stage. As they approach the airfield, the missiles use the same infrared imaging feed to line up over their assigned runway or taxiway. This stage of the process resembles the guidance of the SY-53G.
As the missile passes over its designated launch point, it releases its munitions at approximately 200-meter intervals. A parachute on each munition stabilizes its descent and points its nose toward the ground, at which point a rocket booster propels it downward with enough energy to punch through the concrete tarmac and explote underground. The underground explosion cracks the concrete overhead and heaves it upward, requiring more clearance effort than a simple bomb crater.
Specifications (DRH-35):
- Mass: 35 kg
- Length: 1.68 m
- Diameter: 120 mm
Launch platforms
The SY-56 is an exclusively submarine-launched weapon, with no air-launched or land-launched variants. Aircraft on anti-airstrip missions would carry runway-cratering bombs or SY-53 Pok-u cruise missiles, and land-based anti-airfield missions would be performed by long-range rocket artillery systems like the H41G1B6 Dolpung. Because of its wide, rectangular form, the SY-53 Pok-u did not lend itself easily to the design of a submarine-launched variant, so the SY-56 was developed as an entirely different system. It does, however, use the same DRH-35 runway-cratering bombs released by the SY-53.
At the time of the Second Pan-Septentrion War in April 2022, only Menghe's Chŏngsangŏri-class submarines were confirmed to have been modified to support the firing of the SY-56, and only via their vertical missile launch tubes. Menghean press reports claim that Daedam-class submarines commissioned after 2021 were also capable of using the SY-56, but no Daedam-class submarines fired SY-56 missiles over the course of the war.
War crimes controversy
In addition to its six runway-cratering munitions, the SY-56 contains a secondary munition compartment packed with anti-personnel mines. It disperses these mines continuously while flying overhead. These mines, which are activated 30 seconds after release and detonate when tipped or handled, are meant to delay repair efforts by creating an unexploded ordnance (UXO) hazard for ground crews. To further delay clearance efforts, the anti-personnel mines are embedded in plastic shells molded and textured to look like rocks and displaced concrete fragments. This has the intended side effect of forcing ground crews to treat actual bomb rubble with an abundance of caution.
The SY-56's secondary munitions were not revealed to the public at weaponry expos, and official documentation only referred to its runway-cratering munitions. This left Entente ground crews with no advance warning about the UXO hazard posed by materials resembling debris. Moreover, Entente airbases on mainland Khalistan called on civilian contractors to support runway repairs, meaning that civilian ground crews bore the brunt of injuries and deaths due to Menghean rubble bombs.
Following the Second Pan-Septentrion War, the governments of Anglia and Lechernt, Khalistan, Portcullia, and Sieuxerr accused Menghe of commiting war crimes through the use of SY-56 cruise missiles in against targets where civilians would be expected to conduct airbase repairs. Menghe rejected these accusations on the grounds that it is not a party to any treaties on the use of land mines (nor are the other major PSW2 combatants). A Menghean military spokesman also claimed that the SY-56's submunitions are fitted with 72-hour self-destruct timers, though independent fact-finding missions report that many submunitions remained armed and active well beyond that time, possibly because their fuses were damaged during deployment and clearance operations.