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The HY-2 Haiying (Chinese: 海鹰; pinyin: hǎiyīng; literally "Sea Eagle"), known in Western media as the Silkworm missile, is an anti-ship cruise missile made by the People's Republic of China and still used by many countries in the Middle East. Since the 1980s, the Silkworm has been superseded in the Chinese military by the far more sophisticated Yingji series. The missile is also designated as C-201.

Contents 1 Specifications 2 Design 3 History 4 Derivatives 5 HY-4 6 XW-41 7 Naming confusion 8 Operators 9 References 10 External links

It is based on Shang You (SY), meaning Upstream anti-ship missile, which in turn, was based on the Russian SS-N-2 Styx missile. The missile looks almost identical to the Shang You (SY) anti-ship missile, and has similar performance. It has a maximum range of 95 km, with a 513 kilogram payload.

During its deployment, China discovered that the Shang You (SY) anti-ship missile could only be used by small missile boats with very few electronic components. When the missile was deployed on larger ships containing many complex electronic components, the missile proved subject to severe compatibility problems. This incompatibility could have resulted in the accidental ignition and/or possible explosion of the missile when all of the electronics on the ships were turned on to their maximum capacity.

Orders were given to solve the problem, and Hai Ying (HY) or Sea Eagle anti-ship missile was the answer. However, due to the political turmoil in China, such as the Cultural Revolution, the program did not succeed until the 1980s, too late for the planned platform, the Luda class destroyer, which was called upon for ballistic missile test missions in the Pacific Ocean. As a result, none of the Luda class destroyers deployed in that mission carried anti-ship missiles.

Once the Hai Ying (HY) anti-ship missile entered mass production, however, the Shang You (SY) anti-ship missile was not phased out immediately. Instead, it was continuously manufactured in parallel, as a cheaper alternative for export, as well as to arm the numerous classes of much smaller missile boats of the massive force, which totaled several hundreds, but eventually, Shang You (SY) anti-ship missile was replaced by its improvement, the Hai Ying (HY) anti-ship missile in Chinese service.

The Silkworm was developed at the Institute of Mechanics under Tsien Hsue-shen, a Chinese scientist who did his graduate studies at MIT and Caltech, before being deported by the United States in 1955 after being suspected of Communist ties. A book about this scientist's life was written by Iris Chang, entitled "Thread of the Silkworm."

The Silkworm gained fame in the 1980s when it was used by both sides in the Iran-Iraq War; both countries were supplied by China. During the Gulf War, Iraq used the Silkworm as a surface to surface missile by firing at least two of them at the coalition positions in Kuwait more than 100 km away, but both missed because the range of the missiles is only 80 km.

On February 25, 1991 a shore-based launcher fired two silkworm missiles at the USS Missouri (BB-63) which was in company with the USS Jarrett (FFG-33) and HMS Gloucester. A Sea Dart missile from the Gloucester shot down one Silkworm and the other missed, crashing into the ocean.^[1] More recently, the missile was used by Iraq in the 2003 Iraq War^{[citation needed]}.

In March 1988, China agreed to stop supplying Iran with HY-2 missiles, though it is reported that supply continued into 1989. Iran has since developed the capability to manufacture these missiles itself.

During the 2006 Lebanon War, it was initially reported that Hezbollah guerillas fired a "Silkworm missile" at an "Israeli battleship" off the shores of Lebanon. Israeli sources later said that the missile used instead was a more sophisticated Chinese Yingji-82 (C-802). (Notably, Syria and Egypt employed Soviet Styx missiles--the Russian-made precursors to the Silkworm--against Israeli warships in both the 1967 War of Attrition (following the Six-Day War) and the 1973 Yom Kippur War. While the missiles were ineffective during the 1973 conflict (Battle of Latakia), four Styx missiles were used to devastating effect against the Israeli destroyer Eilat in October 1967, marking the first time that ship-to-ship missiles were successfully used in combat.)

While it is not a particularly sophisticated missile when compared to others such as the Exocet, the Silkworm's unusually large warhead ensures that a single hit will inflict very serious damage.

In addition to the Shang You (SY) family for small missile boats that remained in large scale production for sometime, there is another anti-ship missile that is specifically designed to be launched from shore. This family is the Fei Long (FL) or Flying Dragon anti-ship missile.

The Fei Long (FL) family is the cheapest among all three, because its requirement is the lowest: Due to the fact that the missile is stored in warehouse on land, the salinity, temperature and relative humidity requirements for the missile itself are greatly reduced, since these factors can be controlled environmentally. Because it is designed and deployed on land, the associate C4I systems can be located separately, the distributed system avoids the electromagnetic compatibility requirement, and should any of the components of the C4I system are struck by the enemy, this distributed system of Fei Long (FL) family would greatly reduce casualties and damages. All of the system of Fei Long (FL) family can be used by the Hai Ying (HY) or Shang You (SY) families, but not vice versa because the former is not designed to be deployed on ships. In contrast to the Shang You (SY) family of anti-ship missiles, the Fei Long (FL) family has much longer production run.

The HY-4 variant of the C-201 is a mid-range ground-, air-, and ship-launched cruise missile. Development of the C-201 HY-4 is believed to have started in the mid-1970s, replacing the C-201 HY-2 liquid propellant sustainer motor with a small turbojet engine, and adding a the monopulse active radar seeker. Apart from the substitution of the turbojet engine, the overall configuration of the HY-4 variant of the C-201 missile is similar to the HY-2 variants of the C-201, with two delta wings and tri-form rudder and tail. The missile has a radio altimeter which allows the cruise height to be varied between 70 and 200 m altitude, followed by a steep dive onto the target.

• Developer: China Sea Eagle Electro-Mechanical Technology Co.
• Length: 7.36 m
• Wingspan: 0.76 m
• Weight: 2.4 m
• Warhead: 1,740 kg
• Speed: Mach 0.8 – 0.85
• Range: > 150 km
• Cruising altitude: 70 – 200 m
• Propulsion: one turbojet engine and one solid rocket booster

An improved version of the HY-4, known as the XW-41, has been developed. This latest version of the C-201 missile family is said to have a 300km range with additional GPS/GLONASS guidance. However, due to the availability of more advanced anti-ship missile with similar range, such as the C-602, the future of XW-41, like others in the Silkworm missile family, is uncertain despite its successful trials.

The name Silkworm may be slightly inaccurate. Coined by Western analysts, this term has been apparently used to refer to both HY-1 and HY-2 missiles. C-201 is the numerical designation used by Chinese for these missiles.

The HY-1 missile, NATO codename CSS-C-2 has been nicknamed both Silkworm, and Sea Eagle (from the Chinese Haiying).

The HY-2 missile, NATO codename CSS-C-3 has been nicknamed Seersucker, Sadsack and Silkworm. This is the missile China has exported to many Middle Eastern countries, and is the missile referred to in this article, and in the mainstream media.

Both the Shang You (SY) and the Fei Long (FL) families of anti-ship missiles are often also referred as Silkworms.

These weapons are, however, very similar to each other.

•  People's Republic of China
•  Iran
•  Iraq

• Federation of American Scientists page on HY-1
• HY-2