CIWS naval gunnery in the anti-missile role

Over the past decade the threat of attack from anti-ship missiles (ASMs) has become the principal fear of a warship's command team. This perception evolved from both the UK Royal Navy's experiences during the Falklands war and subsequently by damage caused to the United States' guided-missile frigate Stark, which was hit by two Exocet missiles in the Persian Gulf in 1987.

The Stark incident is notorious for several reasons, including the fact that a key element in the ship's anti-missile defense, the Phalanx close-in weapon system (CIWS), was not turned on when the attack came. Phalanx and others like it have become essential for all types of ship, large nd small. Weapon performance and operational philosophy is currently the subject of much debate as existing CIWS are modified and new systems are designed. Phalanx evolves towards Block 2 General Dynamics' (GD) Air Defense Systems division has buit approximately 675 Phalanx systems since production began in 1979. The weapon is operated by the US Navy and 10 other countries, namely: Australia, Canada, Greece, Israel, Japan, Pakistan, Portugal, Saudi Arabia, Taiwan and the United Kingdom. All export sales apart from the Canadian order have been on an FMS basis, although GD itself also markets the system internationally. The company is actively promoting Phalanx to the Australian and New Zealand navies to arm their ANZAC frigates, for which the system has been selected as the baseline fit but has not yet been formally ordered, GD is also pusuing prospects in Thailand, which has been wavering over the selection of a CIWS for several years, the Phalanx will probably arm the Brazilian navy's planned new frigates if Bath Iron Works in the US is selected to supply the hulls.

The Israeli navy's future Sa'ar 5 corvettes, being built by the Ingalls shipbuilding division of Litton in the US, are also expected to receive Phalanx.

The present production version, Block 1, incorporates improvements over the original Block 0 in the form of an increased radar search volume, an enhanced fire control system, a larger magazine holding 1,500 rather than 1,000 rounds, an increased maximum rate of fire (to 4,500 rounds/min), the ability to engage high-angle targets, higher reliability and easier maintenance requirements.

GD has already built about 150 Block 1 installations, both as new mounts and in the form of "ordalt" (ordnance alteration) kits to convert Block 0 systems. The first four Block 1 systems were installed aboard the battleship USS Wisconsin in August 1988. Production of Block 1 was formally authorized in the spring of 1990 with the completion of fleet operational test and evaluation (FOT&E), which demonstrated what GD describes as "superb" results. The US, Australian, Greek, Japanese, Taiwanese and UK navies are already introducing the Block 1 variant.

General Electric, which is qualifying as second source for Block 1 porudction, will build half the total number of weapons in each year under Fiscal Year 1989, FY1990 and FY1991 funding. The US Navy plans to retrofit all its Block 0 installations to Block 1 standard. Production of Block 1 systems -- both as new weapons and as ordalt kits -- it likely to exceed 800 for the US Navy and other customers.

Additional improvements will be introduced progressively within the Block 1 program. In March 1990, General Dynamics received a contract to develop a new computer that will run at least 100 times faster than the present machine. This will allow Phalanx to engage more difficult targets -- such as violently manoeuvring missiles -- and extend interception ranges. The new computer will be based on the Control Data AMP (Advanced Modular Processor), using MIPS Computer R3000 RISC microprocessors. Software will be written in Ada, compared with machine langauge for the in-service unit, thereby simplifying programming and making future upgrades easier.

Further improvements will result from the Block 1R-III program, under which General Electric is replacing several radar sub-systems in order to enhance reliability. These include a new transmitter, to be supplied by Thomson-CSF of France, and a new signal processor.

The next major step change will be to Block 2 standard, intended to counter the introduction of faster, more stealthy, anti-ship missiles and further extend engagement ranges. The US Navy has drawn up an operational requirement for Block 2, and is expected to issue requests for proposals covering full-scale development (FSD) in late-1991 or early the following year. The FSD contract is planned to be awarded at the end of 1992, with Block 2 entering service at the end of the century.

Improvements that are likely to be demanded for Phalanx Block 2 include higher gun performance in terms of greater muzzle velocity and/or projectile mass, an increased rate of fire and higher accuracy; additional sensors, probably including infra-red search and tracking; and greater realibility. Keeping ship modifications to a minimum is expected to be an important consideration.

General Dynamics and the US Navy are studying candidate gun systems for Block 2, ranging in calibre from 20mm to 30mm. GD points out, however, that an increase in calibre from the present 20mm of the M61A1 is not a foregone conclusion. Under a feasibility study contract awarded by GD out of its discretionary funds. Oerlikon-Contraves is testing its Gatling 5000 seven-barrelled 25mm weapon mounted in a stardard Phalanx production turret. Firing trials began at the Swiss company's Ochsenboden proving grounds in May 1990.

Oerlikon-Contraves says that the Gatling 5000, which has already been adopted for the Breda Barrage/Myriad CIWS program, has a higher rate of fire and muzzle velocity than any other Gatling gun. The weapon fires 25x184mm KBB ammunition, also known as Super 25, which contains a greater weight of propellant than other 25mm rounds. This confers a muzzle velocity of 1,260m/s with the AMDS (Anti-Missile Discarding Sabot) round, or 1,280m/s with APDS-T.

GD is also discussing several candidate weapons with General Electric, including those using case-telescoped ammunition. A variant of the CIWS known as Phalanx 30, based on a GE GAU-13/A four-barrel 30mm Gatling gun, was test-fired some years ago. Advanced guns being studied by Tround International may also be candidates for Block 2.

General Dynamics is also studying a possible combined point-defense/CIWS installation in which the Phalanx radar would provide target information to a separate RAM (Rolling Airframe Missile) system. This would extend the maximum engagement range and increase the number of targets that could be engaged simultaneously. Electro-thermal chemical solutions Looking further to the future, the US Navy has awarded parallel contrracts to FMC Advanced Systems Center and General Dynamics Land Systems for the provision of cartridges to support testing of a high-rate-of-fire electro-thermal chemical (ETC) test rig based on an Israeli 60mm gun. The FMC contract, valued at $1.5 million, calls for cartridge delivery in August 1991. Both companies have also submitted designs for an associated autoloader.

The US Naval Sea Systems Command is managing the system study under the auspices of the Department of Defense Balanced Technology Initiative (BTI). It could ultimately lead to the development of a new generation ETC CIWS suitable for installation aboard a future warship fitted with an integrated electric drive propulsion system.

Propelling charge development is under the control of the Los Alamos Laboratory, while the requisite electrical pulse power generation system is being developed by the David Taylor Research Center.

The Naval Surface Warfare Center, Dahlgren, is the designated system integrator and is overseeing modification of a CIWS mount plus the development of an associated small-calibre smart munition (SCSM). The latter is expected to exploit technology originally developed under the auspices of the Defense Advanced Research Projects Agency (DARPA) as part of the SDI program.

DARPA work included the design and development of the General Electric D2 hypervelocity projectile to be launched from a 40MJ 105mm round-bore electromagnetic gun for endo-atmospheric intercepts. Other participants in the program included SAIC as system integrator; Maxwell Laboratory, providing switches; Eglin, responsible for batteries; and Sparta, responsible for the barrel. Subsequently, GE in association with General Research Corporation Santa Barbara, devised D3, a tactical version of D2 with a tungsten penetrator.

DARPA had planned to look at applications of D3 for land-based air defense and anti-tank applications, but funding ran out. Elements of the system may well be revived as part of the US Navy's ETC program, which reportedly began in March 1990. The study is expected to be concluded with an integrated firing at the end of 1992. Barrage saturates the window Oerlikon-Contraves of Switzerland and Breda Meccanica Bresciana of Italy have jointly developed a new CIWS, also based on the Oerlikon-Contraves 25mm Gatling 5000 in a twin installation. First announced at the Mostra Navale exhibition in Genoa in 1989, the Myriad is being developed by a team which also includes Selenia and Elsag in Italy, which are responsible for the Kaband acquisition and W-band tracking radars and the MAGICS console to which both gun and director are connected via a 10Mbit/s MHIDAS databus.

The twin installation in a single mount (known as Barrage) will result in a cyclic rate of fire of 10,000 rounds/min, providing an exceptional projectile density to defeat high-speed multiple, manoeuvring targets. The Oerlikon-Contraves KBB ammunition, particularly the sub-calibre AMDS KE projectile, has a very low aerodynamic drag coefficient, which combined with a high muzzle velocity (1,270m/s) ensures reduced time of flight and minimized prediction errors.

The AMDS penetrator consists of a tungsten alloy and is spin stabilized to penetrate heterogenous materials forming nulti-armoured protection while remaining sufficiently ductile to avoid breaking up during the process of penetrating the missile front assembly. A dual ammunition feed system developed by Oerlikon Contraves, which supplies the guns with linkless ammunition, is designed to feed either of two types of ammunition and is also equipped for redundant mode operation.

The absence of belt links increases functional reliability while optimizing ammunition packing density. Spent cases are returned to a separate container. Feedback into the magazine will also be possible. A special feature of the Gatling 5000 is its patented hangfire safety mechanism, which prevents a round being fired from an unlocked breech.

Like the Sea Guard CIWS, which has been adopted by the Turkish navy for its MEKO 200 frigates, Myriad is mounted on an inclined platform in order to engage zenith attacks from high-diving missiles. The Barrage mount carries 2,000 rounds in four boxes, two per Gatling gun. Total weight of the system, including ammunition is 7,700kg (each gun weighs 1,600kg including 1,000 rounds of ammunition). Rate of train (elevation) is 2.5 (3.0) rad/s.

Myriads's very high rate of fire is designed to saturate the "window" through which future supersonic manoeuvring anti-ship missiles will pass as they approach their target, thus defeating weapons that would otherwise "outmanoeuvre" a CIWS with a fire control that had to predict a target's future motion.

At the time of writing, prototype weapon assemblies had completed their qualification program in the summer of 1990 and were being examined for system compatibility in their fully integrated test configuration. Weapon tests involving two identical independent weapon systems took place towards the end of 1990. These weapons were expected to have been handed over to Breda by the end of 1990. Total system integration of the two weapons is planned to take place in 1991, during which time Oerlikon-Conraves is expected to complete a reliability growth program involving its own prototype. Operational testing should be completed in 1992 and service introduction is planned for 1993. Goalkeeper sets the standard Most recent publicity about CIWS has surrounded the well-known Goalkeeper, which successfully underwent a combined US-UK trial in the United States in the summer of 1990 against several types of anti-ship missile including the Exocet, Harpoon and Maverick. The final report of the trials, which has not been made public, was due to have been complted by the end of November 1990.

The US first expressed a desire to conduct a joint trial of Goalkeeper in 1986 after Donald Rumpf, Assistant Secretary of the Navy (Research & Engineering) visited the UK MoD and the Director or Operational Requirements (Sea). At the time, the US was examining the concept of a "CIWS 2000" which would succeed Phalanx. The US was looking to enhance Phalanx to meet threats in the next century and a new system and, possibly, an off-the-shelf purchase of an existing weapon.

In 1987, the then Chief of Surface Warfare, Admiral Joseph Metcalf, had tried to cancel CIWS 2000 on the grounds that proposed solutions represented an insufficient advance over Phalanx, and in January 1988, a Congressional committee refused further funding for CIWS 2000 until Goalkeeper was evaluated. In the event, a decision was taken in favour of enhancing Phalanx in early 1990, shortly after an MoU between the US and the UK to trial Goalkeeper was finally signed, some two years after Congress had originally decided to approve funding.

The trials, which took place over four months during the summer of 1990, were christened "Stoddard" after the Fletcher-class destroyer that served as the target ship. The weapon supplied for the trials was a normal production delivered version from Signaal.

Goalkeeper combines General Electric's 30mm seven-barrel GAU-8/A Gatling gun (originally selected in preference to Mauser's quadruple 30mm SEM-30) and a linear-array X-band search radar on the mount which relays target data to a dual-band (X and Ka-band) radar also on the mount. Once the X-band tracking radar receives the target, the Ka-band with its smaller beam width (0.6 degree as opposed to the X-band's 2.4 degree) takes over. The Ka-band radar has a wavelength of only 8mm, and thus a very narrow beam, which reduces reflections from the sea at low altitudes.

In automatic mode, Goalkeeper's total reaction time against a target with a speed of Mach 2, at sea skimming altitudes, is 5.5s with target engagement at approximately 1.5km and a maximum kill probability at around 300m.

The first Dutch vessel to carry Goalkeeper was the frigate Callenburgh. Goalkeeper is also being fitted to the eight "M" Type Karel Doorman-class frigates, is fitted to two Jacob van Heemskerck frigates, and has been retrofitted to 10 Kortenaer-class frigates to replace their 40mm mounts. The replenishment vessel Zuiderkruis was also fitted with Goalkeeper on a platform erected aft of its stack during deployment to the Persian Gulf at the end of 1990.

Goalkeeper was introduced into service in the UK Royal Navy in November 1988 after successful trials aboard the Type 22 Batch 3 Type 22s are equipped with a single Goalkeeper in addition to their Sea Wolf point-defense missiles. The Invincible-class aircraft carriers are each receiving three Goalkeeper during refit, replacing the Mk15 Phalanx with which they were equipped during the Falklands war. Spain's 12-barrelled solution The Spanish navy's aircraft carrier Principe de Asturias is also equipped with a CIWS in the form of four Meroka systems developed by CETME, now a business unit of Santa Barbara, and built by Bazan at its San Fernando facility. Meroka employs 12 20mm barrels arranged in two horizontal rows. Each round weighs 320g, including the 102g projectile. Rate of fire is 9,000 rounds/min in a burst that lasts 0.08s. Meroka fires two such bursts per second. Ready use ammunition is 720 rounds (60 per barrel), which may be increased to 2,160 in an enhanced Meroka which has been studied. Muzzle velocity is 1,300m/s.

Following initial detection by an Orion RTN-12L/X search radar at ranges up to 15km, targets are passed to Meroka's own I-band tracking radar, an on-mount Lockheed Electronics PVS-2 Sharpshooter which begins to track targets at approximately 5km. Targets are designated via a Selenia PDS-10 tactical data console and fired upon within an engagement envelope between 2,000m and 300m. Total reaction time is under four seconds. There is also a back-up optronic system for use in a severe ECM environment. This includes an Israeli-developed TV camera, believed to be an EL-OP system. Both the tracking radar and the optronic system are currently the subject of an improvement program.

In addition to the Principle de Asturias, Meroka is also installed on the Spanish navy's Santa Maria-class frigates and space has been provided for a mount on the new Spanish oiler, Mar del Norte. Meroka is also likely to be installed on the Spanish navy's future F-100 frigates and has been considered for installation on the Descubierta-class corvettes. Sea Trinity to go on trial Sweden's 40/L70 Sea Trinity CIWS is due to be trialled against aircraft and high velocity towed targets on a variety of platforms including minehunters and coastal corvettes between 1991 and 1993. The first trials will take place on board the SMYGE stealthy surface-effect ship (SES) built at the Karlskrona shipyard (see IDR 11/90 pp. 1271-1272).

The Trinity is derived from the 40mm/L70. Work on Trinity commenced in the early 1980s and the weapon was first announced in 1984 with initial tests in 1985-86. Trinity is a 40mm weapon with greatly improved ammunition over earlier versions of the 40/L70. The new 3P (pre-fragmented, proximity fuzed, programmable) shell with higher energy propellant increases muzzle velocity with a slight increase in weight (1.1kg as opposed to 0.8kg for the earlier PFHE round). When it bursts, the 3P round produces 3,000 fragments, including 1,000 tungsten alloy pellets. The programmable fuze can be set as the round enters the breech (for proximity or point detonation) and the burst pattern can also be preset, usually to provide a fan-shape pattern against a sea-skimming missile.

Sea Trinity carries a total of 99 rounds in two chambers either side of the gun (thus two types of round may be stored). According to Bofors, Sea Trinity would typically fire 5-15 rounds in a programmed burst. The gun itself is rated at 330 rounds/min. Bofors claim the effective range of the gun against sea skimming missiles is 2,500m (between 2,000m and 3,000m against a low flying aircraft).

Trinity was originally designed by Bofors as an integrated system with its own sensors. The mount, which is largely non-magnetic (with the exception of the elevating mass) includes a Bofors proprietary microprocessor, an as yet unchosen radar (either the Bofors Ku-band or Ericsson Ka-band model), a laser rangefinder, gyrostabilized reflex sight and an image intensifier. The stealthy version of Trinity which Bofors was asked to study by the Swedish Defence Material Administration may rely on optronic tracking alone. This version of the mount is shaped to reduce radar cross-section and also incorporates radar absorbing materials. Vierling makes its debut The latest addition to the CIWS family is the Vierling, first displayed in public at the 1990 Defendory exhibition in Greece (see IDR 11/90, p. 1271). Sea trials of Vierling are due to commence later in 1991.

Few details have been released, but Vierling is known to be based on Mauser 27mm guns in a quadruple arrangement with independent ammunition feed for each barrel.

Vierling has a combined rate of fire of 7,200 rounds/min and will use specially developed APFSDS (Armour-piercing Finstabilized Discarding-sabot) ammunition developed by Mauser. The lightweight mount, which requires no deck penetration, weighs some 3,500kg, including 1,440 rounds on mount. Vierling has a traverse rate of 150 degree/s and a traverse acceleration of 150 degree/sec2. The mount is capable of traversing through 360 degree and from -10 to 80 degree in elevation at a rate of 80 degree/s, 210 degrees/sec2 acceleration.