Missile HY-2 Silkworm (CH-SSC-3 Seersucker)

The HY-2 was the second Chinese anti-ship missile drawn from the Soviet P-15 Termit, which China had already copied as the SY-1. Work on a longer-ranged coastal-defence weapon began in April 1965, and two proposals ran in parallel: a conservative stretch of the SY-1, which became the HY-1, and a fuller re-engineering approved by the state in August 1965 and named HY-2 the following year. The HY-2 airframe was lengthened again around a load-bearing box structure that carried substantially more propellant, with a higher-thrust solid booster, a longer sustainer burn and a more accurate mid-course autopilot. A static test article was assembled in August 1966 and the design was certified in March 1970 after firing trials scoring six hits in seven launches and ten in eleven. The HY-2 then displaced the HY-1 from the coastal-defence role, while the HY-1 continued as a shipboard weapon on the Type 051 destroyer; the HY-2 launcher would not fit even that ship, the largest surface combatant China then had, so the missile served only from shore. Export rounds carry the designation C-201. The NATO reporting names separate the two: Silkworm belongs to the land-based HY-1 and Seersucker to the HY-2, but Western reporting has applied Silkworm to the whole family since the 1980s.

The configuration follows the Styx — cylindrical fuselage, two delta wings, a triform tail — with a solid rocket booster that separates a little over two seconds after launch and a liquid-fuelled sustainer burning a hypergolic acid-and-amine mix. The propellant is corrosive and toxic and fuelling crews work in chemical suits, which bears directly on how quickly a battery can be readied. After separation the missile climbs to about 400 m, levels off and cruises between 100 and 300 m at high subsonic speed until the terminal radar switches on and searches the sea ahead; on acquisition the autopilot puts the round into a dive onto the target. Nothing is asked of the launch site after firing, so the position can stay concealed. The warhead fills the full fuselage diameter, and unburned fuel adds an incendiary effect on impact; one round can sink or disable a destroyer-sized ship. A battery covers a firing sector of ±85 degrees and is served by a truck-mounted C-band surveillance and tracking radar of Soviet naval ancestry. Single-shot hit probability is quoted at 70 per cent.

Variants differ mainly in terminal seeker and altimetry. The HY-2A replaced the conical-scanning radar with a passive indium-antimonide infrared seeker; it was first fired successfully in December 1975 and certified in 1982, and later marks added a radio altimeter, a second-generation seeker and a cruise height cut to 20 m. The HY-2B substituted a monopulse active radar seeker and a precise radio altimeter that steps the missile down twice on the run in, certified in January 1984, with a frequency-agile seeker tested in 1989. The HY-2C used a television seeker. The HY-2G fitted a high-precision radio altimeter to hold a 30 to 50 m approach and was retrofitted to rounds already in service from 1981. The HY-2J was the mark exported to Iraq. A turbojet-powered development of the same airframe became the HY-4, and an air-launched derivative for the H-6 bomber became the YJ-6.

China exported the missile from the mid-1970s and formally offered it on the world market in 1984. Recipients include North Korea, Iran, Iraq, Egypt, Pakistan, Bangladesh, Myanmar, Albania, Cuba, Sudan and the United Arab Emirates. North Korea took delivery of roughly 200 rounds between 1976 and 1982, acquired production capability and later extended the range of the missile it fields as the KN-01. Iran reverse-engineered the design as the Raad, in production from 2004 and in service from 2007.

Combat use began in the Iran–Iraq War, both belligerents having been supplied by China; the first shipments to Iran arrived in the summer of 1986. In 1987 Iranian batteries on the Faw Peninsula struck the Liberian-flagged tanker Sungari and the US-flagged Sea Isle City in October, with five earlier rounds landing in Kuwait. Kuwait's Sea Island offshore oil terminal was hit the same month, prompting the deployment of a MIM-23 Hawk battery on Failaka Island, and a further launch in December 1987 struck a decoy barge instead. The firings showed the missile reaching well beyond the 80 km previously credited to it. China attributed the transfers to North Korea and stated in March 1988 that it would stop selling anti-ship missiles to Iran, though deliveries reportedly continued through 1989. On 25 February 1991 an Iraqi shore battery fired two rounds at USS Missouri; HMS Gloucester destroyed one with a Sea Dart and the second fell into the sea. A round recovered at Umm Qasr is held by the Royal Air Force Museum Midlands. Iraq fired at least two in surface-to-surface mode at coalition positions in Kuwait during the 2003 invasion. On 12 October 2016 two missiles launched from Houthi-held Al Hudaydah at USS Mason in the Bab el-Mandeb impacted the sea, possibly defeated by countermeasures.