D+I 2007: Arming the Navy's big ships
By Julian Kerr
With the major decisions now made on the Navy’s AWD and LHD programs, the DMO is filling in the blanks as far as point defence armament and fire control systems are concerned.
Requests for Tender (RFT) for a number of Air Warfare Destroyer (AWD) weapon systems will be released before the end of this year for decision in mid-2008, according to Commodore Andrew Cawley, Director-General of the AWD program.
While the core Aegis combat system was mandated by Government for the AWD and three systems are to be supplied via the US Foreign Military Sales (FMS) program, a decision has yet to be made on whether other AWD weapon systems will be acquired by FMS - if US-made - or direct from the manufacturers.
“We’re currently going through the process of prioritising draft RFTs before release,” Commodore Cawley told ADM.
“A decision on which way to purchase will be made as part of the RFT evaluation process.”
The Navantia F100 design chosen for the three Hobart-class AWDs includes 48 Lockheed Martin Mk 41 Vertical Launch Systems (VLS) – 16 less than the Evolved Arleigh Burke AWD design unsuccessfully proposed by Gibbs and Cox.
Commodore Cawley said the RAN had selected the largest sizing of the VLS, capable of carrying “anything the US Navy decides it wants to fit into those cells.”
This includes the Tomahawk BGM-109 land attack cruise missile, although as yet there has been no indication that Government is considering the purchase of the politically-sensitive, 1,100km-range weapon.
Each of the 48 VLS cells will store and launch either a single Standard SM-2 medium range air defence missile, or four Evolved SeaSparrow (ESSM) short-range air defence missiles packed in a quad canister.
The obsolete SM-1 missiles aboard the RAN’s four Adelaide-class guided missile frigates (FFG) are in the process of being replaced by the SM-2 Block IIIA as part of the complex and behind-schedule FFG upgrade program.
The SM-2 Block IIIA features improved performance against low-altitude targets and a new Mk125 warhead with heavier grain explosive. Its range of more than 160km is almost double that of the SM-1.
The variant that will eventually deploy aboard the first AWD in seven years time is likely to be a later development, probably the Block III B which includes a number of modifications over previous versions, including a side-mounted infrared seeker to supplement the missile's semi-active radar guidance.
SM-2 Block IIIB has been requested by South Korea for its KDX-III Aegis destroyers.
Japan, which is actively pursuing a joint missile defence program with the US, already has the SM-2 Block IIIB aboard its Kongo-class Aegis destroyers as well as the SM-3 extended range missile used to defend against short to intermediate-range ballistic missile threats in the midcourse phase of flight.
The SM-3 features a Third Stage Rocket Motor in addition to the SM-2 Block IIIB’s booster and rocket motor, a GPS/INS guidance section, and the LEAP (Lightweight Exo-Atmospheric Projectile) hit-to-kill kinetic manoeuvring warhead.
John Davis, Combat Systems Director of the AWD Alliance, said upgrading from SM-2 to SM-3 would require some software and hardware changes for Aegis but these were anticipated in the growth path. The same applied to the SM-6, which is being developed to meet the US Navy's requirement for an extended range anti-air warfare (ER-AAW) missile.
As explained by Commodore Cawley, “The software model that we put to sea on the first ship in 2014 will be capable of firing the weapons of tomorrow. It might be something on the margins of new technology – whatever it is that the ADF chooses.”
The upgrade for SM-3 is thought to include Aegis LEAP Intercept computer software and hardware, as well as Long Range Surveillance and Track Aegis enhancements.
When used in conjunction with Co-operative Engagement Capability (CEC) components, the result is a single integrated air defence tactical display available to all CEC-equipped ships in the area – a display that can if necessary be used to help guide long-range anti-air missiles launched from other ships.
Davis confirmed that CEC would be included in the baseline Aegis solution for the Australian AWDs.
However, Canberra-based CEA’s innovative CEAFAR 3D active phased array radar will not be part of the initial fitout.
“Active phased array radar will be on the ship at some point in its life – it’s not a major upgrade per se - but it won’t be in the baseline; the technology isn’t ready for our schedule,” Commodore Cawley commented.
The RIM-162 ESSM short-range missile, already operational on Australia’s FFGs and Anzac class frigates, will provide each AWD with a second tier of defence, engaging antiship cruise missiles and aircraft from a range of about 50km.
ESSM has semi-active radar guidance with thrust vectoring control to improve range, speed and manoeuvrability against very low altitude threats, such as sea skimming cruise missiles. In addition, the missile has proven to be highly capable in intense Electronic Attack environments.
The current intention is for the AWDs to be armed with a single Close-In Weapons System (CIWS) mounted aft.
Commodore Cawley declined to speculate on possible contenders, but stressed that whatever CIWS was selected must be capable of combating attacks by small, fast boats as well as acting as a defence of last resort against anti-ship missiles.
The Meroka CIWS aboard the Spanish Navy’s F100s, featuring 12 20mm Oerlikon cannon in two linked rows of six, is now considered obsolescent. Given that the Rolling Airframe Missile (RAM) development of Phalanx, employing fire and forget missiles, is not intended to engage surface targets, this leaves Raytheon/General Dynamics’ 20mm, six-barrelled Phalanx Mk 15 as an obvious contender.
The Phalanx 1B upgrade includes a Thales Optronics HDTI5-2F thermal imager, improved Ku-band search and track radar and longer gun barrels providing a rate of fire of 4,500rpm. It also incorporates a forward looking infrared sensor (FLIR) which enables it to engage slow-moving or hovering aircraft, and surface targets.
Another contender could be the more powerful (and more expensive) Thales Netherlands Goalkeeper system, which utilises a seven-barrel 30mm Gatling gun, and I-band track-while-scan search and acquisition radar which hands off to a dual frequency L/K-band target-tracking radar for the actual gun engagement.
While Phalanx reportedly can only engage one target at a time, Goalkeeper can track up to 30 targets, engaging the four most urgent. It will minimise the salvo length to engage as many targets as possible and is thought to be able to deal with two pairs of sea-skimming missiles as little as five seconds apart.
Although both weapons have similar maximum ranges of about 2,000 metres, Goalkeeper’s kill distance is reportedly 350 to 500 metres compared to 300 metres for the Phalanx.
Both Phalanx and Goalkeeper provide autonomous target detection and engagement.
“You can exploit the sensors and other aspects of the Aegis system if you choose to, but systems like Phalanx and Goalkeeper are designed to operate in a stand-alone mode,” Commodore Crawley commented.
The relatively small size of the Phalanx round limits its multirole utility, and the USN is now evaluating the formidable Oerlikon Contraves 35mm Millenium gun as a possible replacement. Each of the gun’s Ahead air burst munitions, fired at up to 1,000 rounds per minute, disperses 152 metal subprojectiles which form a wall of lead in a target’s path, giving the gun a missile kill range of up to 2.5 km.
In its standard version the gun is directly linked to a ship’s combat system data bus (CSDB) and accepts 3D target tracking data from any source.
Whatever CIWS system is selected for the AWDs will be backed up by single 25mm guns in remotely-operated stabilised mounts to port and starboard.
An obvious candidate is the Rafael Typhoon mount and Toplite electro-optic targeting system already equipping the RAN’s Armidale class patrol boats. On the Armidales, the mount incorporates the M242 Bushmaster 25mm gun also used on the army’s ASLAV light armoured vehicles.
Another option is the BAE Systems/Rafael Mk 38 Mod 2 gun mount, developed from the Typhoon and also utilising the M242 chain gun, radar, and/or the Toplite package. The USN has ordered 67 of the Mk 38 Mod 2 to provide close-in defence against small craft for Ticonderoga class cruisers, Arleigh Burke destroyers and LPD amphibious ships.
The new 5-inch 62-caliber Mk45 Mod 4 gun to be carried by the AWDs will provide naval fire support out to more than 21 nautical miles (nm) using the new Cargo projectile, the Improved Conventional Munition, and an improved propelling charge. The Mk 45 Mod 2 guns now on the RAN’s Anzac class frigates have a range of 13 nm.
The Mk 45 Mod 4 will also provide an over-the-horizon range of more than 60 nm with the Extended Range Guided Munition (ERGM) and propelling charge. The rocket-assisted projectile is scheduled to enter service with the US Navy in 2011.
The RAN will mate the Mk 45 Mod 4 gun with the US Mk 160 Gun Computer System. Together with the Mk 46 Optical Sight, these three components comprise a fully-integrated sub-system of the Aegis Combat System that in turn interfaces with the US Naval Fires Control System, an automated mission-planning system for naval surface-fire support.
Two four-cell launchers for the Harpoon Block II anti-ship missile will be mounted amidships. Already deployed aboard the Anzac and Adelaide class frigates, Harpoon Block II has been given the accuracy to target land-based threats or facilities in addition to its primary anti-shipping role through incorporation of the Global Positioning System/Inertial Navigation System from the Joint Direct Attack Munitions program.
Davis confirmed the ships would be equipped with a towed array sonar – on current plans, the only RAN combatants to be so fitted – and a hull-mounted sonar. Both would be chosen by open competition.
Each ship would also deploy two double launchers for the Eurotorp MU90 lightweight fire-and-forget torpedo, which has a range of 12,000 metres at its maximum speed of 50 knots.
Current plans are for the AWDs to ship a single Seahawk helicopter in the anti-submarine and utility role. However, the possibility of NFH90 maritime helicopters replacing the RAN’s 16 S-70B-2 Seahawks before they undergo an expensive midlife upgrade and life extension should not be discounted.
The LHD Program Office declined to be interviewed on the possible weapons fit for the RAN’s two new Canberra class amphibious ships, in view of the competition involved.
However, it’s instructive to look at the armament of similar platforms.
All have relatively light defences, on the assumption that as high value assets they will be part of a task force in combat situations.
The French Mistral class LHDs carry two two-cell Simbad (Mistral 2) missile systems and two Goalkeeper CIWS, and the Spanish strategic projection ship on which the Australian LHDs are to be based will feature a single ESSM or RAM system and four Meroka CIWS. The USN’s 25,000 tonne San Antonio class LPDs deploy two RAM systems and two 30mm guns, while the Royal Navy’s helicopter carrier HMS Ocean has three Phalanx CIWS.
The RAN’s LHDs will have the same Saab Systems 9LV combat management system as the Anzac class. The system’s open design should assist any integration necessary should a non-autonomous CIWS solution be chosen.
Copyright Australian Defence Magazine, August 2007