KEEPING THE ENEMY AT BAY – WARSHIP ANTI-MISSILE DEFENCE
Byline: Gordon Arthur / Hong Kong
Perhaps the greatest danger to a warship is an anti-ship missile (AShM) streaking towards it at supersonic speed over the wave tops. A ship has mere seconds to react to an incoming missile fired by submarine, surface combatant, coastal battery or released from aircraft at long range, although it does have several tricks up its sleeve to defeat such attacks. Successful first engagement of the missile is critical because there is no second chance.
Ship countermeasures can be broken down into several areas: missiles; close-in weapon systems (CIWS); decoy systems; electronic warfare equipment; and antiaircraft guns. Passive countermeasures may include stealth technology in the ship’s design to reduce detection and create a harder target, though this article will focus only on the first three listed above.
Incidentally, the USA is concerned about China’s development of the world’s first land-based anti-ship ballistic missile. China’s desire to create such a missile grew from the 1995-96 Taiwan Strait Crises when the country lacked the means to deter US aircraft carriers. Based on a DF-21 medium-range ballistic missile, its reported range of 1,500+km gives it a true anti-access/area-denial (A2/AD) capability. US officials say China may have 80 such missiles in service by 2015. China could equip DF-15 or DF-11 short-range ballistic missiles with anti-ship warheads too, and these would create a morass of new threats if sold to Chinese client states.
1. Anti-missile missiles
The first successful sea engagement of an AShM by a missile occurred in the 1991 Gulf War. The battleship USS Missouri released chaff to deter an Iraqi Silkworm missile, but ironically this chaff was automatically engaged by a Phalanx system on a nearby US frigate. In the end, a Sea Dart missile from HMS Gloucester destroyed the Iraqi missile in this historic engagement.
Missiles are a ship’s first line of defence, and one of the most common Western systems is the short-range Seasparrow, of which the latest version is the RIM-162 Evolved Seasparrow Missile (ESSM). Raytheon’s product has a new rear section, more powerful motor and tail fins for greater manoeuvrability. Four ESSMs fit inside a Mk 41 Vertical Launching System (VLS) and improved Mk 57 GMVLS. Australia, Japan, New Zealand and South Korea are regional ESSM operators, soon to be joined by Thailand.
Another popular system is Raytheon’s short-range RIM-116 Rolling Airframe Missile (RAM). A launcher contains 21 missiles but the system must be integrated with a ship’s combat system. RIM-116 will eventually be fitted aboard some 74 US Navy (USN) ships, including carriers, assault ships, dock landing ships and Littoral Combat Ships (LCS). Licence-produced versions exist on South Korean KDX-II, KDX-III and Dokdo-class vessels. Entering low-rate initial production (LRIP) last year, the latest Block 2 is more effective against highly manoeuvrable AShMs.
The SeaRAM is a current development that combines the radar and electro-optical system of the Phalanx 1B CIWS with an 11-cell RAM launcher. Reliant on its own sensors for autonomous operation, it was developed because of concerns about the ability of gun-based systems to defeat modern sea-skimming missiles. It is still under trial, and one SeaRAM was fitted aboard the LCS vessel USS Independence. It can be easily installed due to an identical footprint to the Phalanx. The USA also possesses the RIM-174A Standard ERAM (SM-6) missile, an upgrade of the SM-2ER designed to hit aircraft and high-performance AShMs. Initial operating capability (IOC) of the RIM-174A is expected this year, and Australia will eventually employ it on Hobart-class destroyers.
The United Kingdom fields the Sea Wolf in two variants – GWS-25 Conventionally Launched Sea Wolf (CLSW) and GWS-26 Vertically Launched Sea Wolf (VLSW). It entered service in 1979, meaning its first combat was the Falklands War in 1982. The GWS-26 Mod 1 will remain in Royal Navy (RN) service until 2020. Regionally, the VLSW is fitted on Malaysian Lekiu-class frigates. Another UK air defence suite is the Principal Anti-Air Missile System (PAAMS), a joint British/French/Italian programme with MBDA as major stakeholder. PAAMS is called Sea Viper on RN Type 45 destroyers, and it offers better performance than the preceding Sea Dart. PAAMS uses Aster 15 short-range and Aster 30 medium-range missiles, and eight missiles can be launched in just ten seconds from a Sylver VLS.
MBDA is also developing the Sea Wolf’s successor, the Common Anti-Air Modular Missile (CAMM), or Sea Ceptor, which shares components with the ASRAAM air-to-air missile. It will replace the VLSW on Type 23 frigates by around 2016 and the Sea Ceptor should have a 30-year lifespan.
Russian systems are used within the region. The 3K95 Kinzhal (SA-N-9 “Gauntlet”) is a naval variant of the Tor and it is mounted on the Russian Navy’s Admiral Kuznetsov carrier, Kirov-class cruisers, Udaloy-class destroyers and Neustrashimy-class frigates. Missiles are stored in rotary VLS modules and the newest type is the 9K332 Tor-M2 introduced in 2008.
The Russian medium-range 3S90 Uragan (SA-N-7 “Gadfly”) is the naval version of the 9K37 Buk. Its successor is the 9K37M1-2 Shtil (SA-N-12 “Grizzly”) that was fitted to later Sovremenny-class destroyers. India acquired a modernised Shtil-1 system on its Talwar-class frigates and Delhi-class destroyers. China has developed it into the HQ-16, while the mainstream short-range missile on Chinese ships is the HQ-7 derived from the French Crotale.
Another missile used locally by India and Singapore is the Barak 1 from Israel Aerospace Industries (IAI). Following a US $330 million contract signed in 2007, India and Israel are collaborating on the new 70km-range Barak 8. It was successfully fired in July 2009.
2. Close-In Weapon System
The most successful systems against sea-skimming missiles involve layered defence with short- and medium-range components. Defensive missiles have a greater range than guns, but what happens if an AShM penetrates that outer shield? This is where the CIWS comes into play, an automated point-defence gun mounted on ship decks. It uses radar to track incoming missiles (either its own sensors or integrated with a ship’s systems) and attempts to shoot them down in a last-ditch wall of lead. Thus, the CIWS is critical on nearly all modern warships. Their guns must be rapid-firing and are typically multi-barrel cannons. They have obvious limitations such as a short kill range often 500m or less. At such ranges, the system has only one-third of a second to respond to missiles screaming in at 1,500m/s! Another problem is that, even if hit, a missile may not be sufficiently incapacitated or destroyed, plus a CIWS can engage only one target at a time. Another problem is that modern AShMs steer intentionally erratic courses on final approach to avoid such countermeasures.
The best-known CIWS is Raytheon’s Phalanx. It features a 4,500-rounds-per-minute, six-barrelled 20mm M61 Vulcan Gatling gun directed by Ku-band radar. The USN has it aboard every class of ship, and 21 other nations use it too. Because it is autonomous, it is ideal for support ships with fewer on-board sensors. The Block 1B added a forward-looking infrared (FLIR) in 1999, and the USA is currently upgrading its Phalanxes to 1B configuration. Regional users include Australia, India, Japan, New Zealand, Pakistan, South Korea, Taiwan and Thailand.
The Dutch Navy uses the similar Thales Goalkeeper and last year the Netherlands announced it would gain radar upgrades, frangible ammunition and an electro-optical tracking system to extend its life till at least 2025. Goalkeeper uses the GAU-8/A Avenger 30mm Gatling gun, and South Korea also fields it. Oto Melara produced the DARDO CIWS but it now focuses on the newer Fast Forty/Twin 40L70 Compact. These feature 40mm Bofors guns, and regional users include Bangladesh, Malaysia and South Korea. Denel produces the 35mm Dual-Purpose Gun though it has not been exported. Spain has the Meroka, and Oerlikon – owned by Rheinmetall – offers the Millennium 35mm system that it claims will engage missiles at ranges 3-4 times greater than a conventional CIWS. In addition, Turkey uses the Rheinmetall Sea Zenith quad-25mm CIWS.
Russia’s equivalent of the Phalanx is Tulamashzavod’s AK-630M, which has a six-barrelled 30mm GSh-6-30K (AO-18) rotary cannon. The system exists on nearly every Russian Navy warship, and its firing rate is higher than the Phalanx’s. Local AK-630 users are China, India, Indonesia, Myanmar, Pakistan and Vietnam. The AK-306 is a lightweight 1,100kg version for smaller ships.
Even more capable is the Russian CADS-N-1 Kashtan CIWS that combines a pair of AO-18K six-barrel rotary cannons with two SA-N-11 “Grisom” missile launchers equipped with eight ready-to-fire missiles and 32 spares. With a 10,000-round-per-minute firing rate, it is used on modern Russian Navy capital vessels, as well as People’s Liberation Army Navy (PLAN) Sovremenny-class destroyers, the newest Vietnamese Gepard-class frigate and newer Indian Navy vessels. Such a gun/missile combination provides more comprehensive protection than a CIWS alone, with the Kashtan’s claimed kill probability listed as 0.96-0.99. The Kashtan-M is an improved version due to become standard in the Russian Navy.
China makes the Type 730 with seven 30mm barrels, a 5,800-round-per-minute rate of fire and 3km range. A new type will probably incorporate missiles (as on the land-based LD-2000). The Type 730 is used on modern Chinese warships as well as Pakistan’s F-22P frigates. A further development is the Type 1130 with eleven 30mm barrels, this first appearing on the aircraft carrier Liaoning.
3. Decoy systems
Systems that fire chaff (aluminium strips), flares or active decoys work to fool incoming missiles by creating false target sets are commonplace on naval vessels. BAE Systems produces the Mk 36 Mod 12 Super Rapid Blooming Offboard Chaff (SRBOC) decoy launching system (DLS) used by 19 navies, including the USN. The short-range, six-barrel SRBOC array is controlled by ship combat information centres. The Mk 53 Nulka active decoy from BAE Systems Australia has become that country’s most successful defence export; the rocket-propelled system’s main feature is that it hovers in mid-air to seduce enemy missiles. Four Nulka launchers are added to the Mk 36 SRBOC to become the Mk 53 DLS. Today it is used on more than 125 Australian, Canadian and US warships. Other DLS examples are the Esterline Wallop Barricade and SuperBarricade, J+S Deck-Mounted DLS, Rafael Integrated Decoy System, Rheinmetall MASS and Terma SKWS. These are generally 130mm in calibre to suit NATO rounds.
While launcher systems change little, advanced dispersion techniques and manufacturing processes have improved chaff payloads. British company Chemring Countermeasures has cornered more than half the global market. Standard radio-frequency (RF) seduction decoys are Mk 182 Mod 1/Mod 2 and Seagnat Mk 214 Mod 0 chaff cartridges. The 1.5km-range Seagnat Mk 216 Mod 1 distraction cartridge is NATO’s standard decoy. Chemring also makes Mk 245A2, PIRATE and TALOS infrared (IR) rounds that create a ship-like IR signature cloud. Chemring’s catalogue includes the innovative Large Payload Carrier and dual-mode IR/RF Chimera round, plus it is working on advanced variable-range rounds. Chemring also offers the trainable Centurion 12x130mm launcher, for which it has high hopes.
Another product is the Irvin-GQ IDS300 Naval Decoy System, a passive RF buoy covered in radar reflectors that resembles an inflated life raft. This expendable “Rubber Duck” decoy (US nomenclature AN/SLQ-49) is supposed to attract enemy radar rather than its parent ship.