PLA's YJ-18 Anti-Ship Missile Useful Against US Carrier Group

Footage of what appeared to be China's YJ-18 anti-ship missile, rumored to be in development, was shown recently in a news report on state broadcaster China Central Television.

If reports about the missile are accurate, it will be China's first combination subsonic and supersonic anti-ship missile.
　　
According to an unnamed source cited by a military affairs column on Chinese news web portal Sina, the YJ-18 will be the basis for a series of models that will be adapted for launch from warships, submarines and from the coast and will likely replace current anti-ship missiles, given its versatility.

YJ-18 Anti-Ship Missile

The People's Liberation Army Navy currently employs several different models of anti-ship missile, which requires a great deal of logistics and maintenance planning.
The six series of anti-ship missiles the PLA Navy uses include the HY series developed from the Soviet-era P-15, the YJ-8/YJ-83 series developed from the YJ-8, the YJ-62 series developed from the YJ-6 and the most recent YJ-12 supersonic anti-ship missile. Imports include the 3M80E/BE and the 3M-54E series. Each of these missile series requires its own launcher and guidance system, which places logistical pressure on the navy, making the simplification of anti-ship models a major priority.

According to overseas media outlets, the YJ-18 is likely similar to the imported 3M-54 Klub series, which itself is part of a series of missiles including the 3M-54E subsonic anti-ship missile, the 3M-54E1 subsonic anti-ship missile, the 3M-14E inertial guided land attack cruise missile and the 91RE1/RE2 anti-submarine missile. The anti-ship and land attack missile variants in the series are said to be the same in their basic structure and their rocket boosters and turbojet propulsion systems are also said to be identical; the difference is that the warhead of the 3M-54E incorporates a fixed rocket propulsion system, which at its terminal stage velocity approaches Mach 3, increasing its defense penetration capabilities. The anti-ship variants of the 3M-54 are over eight meters long however, and weigh over 2,000kg, so they can only be carried on destroyers or larger vessels. The 3M-14E land attack variant is similar in structure to ordinary anti-ship missiles; it is a low altitude sea skimming missile and is reduced to 6.2m in length, weighing just 1,500kg, meaning it can be launched from small and medium-sized naval vessels, such as corvettes. The 3M-14E1 is a remodel of the 3M-54E1 control system, using a highly explosive warhead, to raise the surface impacted by the missile. As they are all part of the same series, they share the same basic structure, and they all have a diameter of 0.533m, which simplifies logistics and maintenance. 

Overseas news reports suggest that the YJ-18 uses the same "flat wing configuration" as the 3M-54E, which resembles the wings of an airplane. It has a high wing aspect ratio, which allows it to ascend rapidly with little drag, giving it an impressive lift-drag ratio compared to the tail fins used by current tactical missiles. It is estimated that the flat wing configuration can bring the lift-drag ratio to 6-8, while the tail fin configurations can normally only reach 2-3. Breguet's range equation states that the lift drag ratio is directly proportional to range, which gives the flat wing configuration a clear advantage over the tail fin configuration, which explains why all long-range missiles, such as the Tomahawk cruise missile, have a flat wing design. 

The disadvantage of the flat wing configuration is also the high aspect ratio, which requires a mechanism for retracting and spreading the wings, otherwise the missile is impossible to load in an ordinary launcher. The flat wing design also makes it hard for the missile to turn. The advantage of tail fins is the smaller aspect ratio, which means they can be more easily loaded into normal launchers and are easier to fold. Missiles with tail fins can propel themselves in any direction more easily and allow for a bigger proportional overload. Propulsion is also better, but the disadvantage is that its lift drag ratio is lower.
　　

Along with the advances in sourcing materials and technology, the size of the structure used to fold the wings has been reduced and missiles can now lean into bends to increase their maneuverability, which has made a flat wing configuration more practical and it appears to have been used for the YJ-62 and even in the C-705 lightweight anti-ship missile, which likely built the foundation for the use of the flat wing configuration for the YJ-18.
The flat wing configuration will give it a larger trajectory than normal anti-ship missiles, which will come in handy when backed up with an aircraft carrier. The Z-18 early warning helicopter believed to being developed by China has a search range of around 100-150 km from the carrier and flies at a height of 3,000m with a radar scanning range of around 200km. This allows the YJ-18 to hit targets within 300km south of the carrier, which is far beyond the range of current anti-ship missiles and this could be extended to 400 km if there was a fixed wing early warning aircraft deployed from the carrier. 

The warhead of the YJ-18 is also reported to be bigger than its predecessors. The 3M-54E has a warhead of around 200 kg and a high terminal stage velocity, which increases its impact and the 3M-54E1 pushes this to 400 kg, which makes them both more effective than warheads currently in service, like the Exocet and Harpoon missiles and the Chinese YJ-83. The YJ-83 uses a 170 kg semi-armor-piercing delayed detonation warhead. Previously anti-ship missiles were designed with the 3000 ton warships in mind, but the escort ships of US aircraft carrier groups are all above 8,000 tons now and Japan Self Defense Force destroyers are all around 6,000 tons, so the greater the power of anti-ship missiles, the more damage they can cause.