The Formidable Class Frigate

FORMIDABLE FRIGATE

The Formidable class frigates consist of 6 ships, with the first built in Lorient, France and the subsequent 5 ships built by Singapore Technologies Marine in the Benoi shipyard. All are now fully operational. The Formidable-class frigate has a full load displacement of 3,200 tons with its dimensions coming in at 114.8×16.3×6.0m. The wide beam of the ship probably reflects lessons learnt from the operation of the Sea Wolf class Missile Gunboats and the Victory class corvettes regarding the need for ship stability. Apparently the stability of the ship has proven highly satisfactory, with the ship performing well during the 39 day voyage home of the Formidable through rough seas of over sea state 6 in the Indian Ocean after completing construction in Lorient, France. It features a CODAD propulsion configuration, with its 4 MTU 20V 8000 M90 diesels delivering a total output of 48,276 hp. Power is delivered through 2 shafts to 2 fixed pitch propellers, with an additional bow thruster for docking maneuvers. Maximum speed for the Formidable is quoted at 27 kts, with cruising speed being 18 kts, and endurance is given as 4000 nm. 4 Isotta Fraschini IFM V1708 diesel generators, each producing 800 kW, combine to produce a total of 3.2 MW of service power on the frigate. Unlike the La Fayette class frigates it is based on, the RSN frigate is constructed entirely of steel. According to RSN programme officials, the weight margins for the design are less critical, thus allowing steel to be used in the superstructure block aft.

The frigate design incorporates radar cross-section (RCS) reduction features previously proven in the French Navy's La Fayette frigate. These include inclined hull sides and bulwarks, low RCS antennas, enclosed mast structures and concealment of ship's boats and replenishment-at-sea equipment behind special low-RCS curtains. The RSN has made no secret of the importance it attaches to the improved survivability it believes will accrue from applying stealth technology.

The attention to Low Observables in the frigate design extends to the Infra Red region. Davis Engineering, a defense technology firm specializing in IR and Extremely Low Frequency Electromagnetic signature management systems, was contracted to provide IR stealth design support to the RSN for the frigate program. While Davis offers different defined levels of IR suppression based on different IR suppression systems, it is not readily observable to what extent the frigate has been equipped with those systems.

Few details are known about how well equipped the frigate is in catering for other areas of LO, such as its acoustic and magnetic signatures, other than the mention of ‘reduced magnetic and acoustic signatures of the ship and its myriad of sensors’ by the Singapore Ministry of Defence. When questioned about sound insulation features while the author aboard the Formidable in IMDEX 2009, the ship’s Engineering officer stated that the diesel generators were fully enclosed in sound isolating chambers, but the diesels providing propulsion weren’t. (This was visually seen via the remote CCTVs mounted in the engine room spaces and the displays output in the Machinery Control Room).

SHIP MANAGEMENT

A key RSN user requirement was to minimise crew numbers by automation of ship systems and adoption of new operational concepts and manning regimes. As a result, the frigate complement will number just 71, plus a ship's flight of 15. One prime example of the automation required for lean manning is the Ship Management System, a tailored variant of the Shipmaster product developed by DCN's equipment business unit. Designed in consultation with the RSN, it is a software-based multifunction system combining both navigation and platform management functions to enable the safe and effective monitoring and control of systems and machinery by a much-reduced watchkeeping team.

The Integrated Bridge System (IBS) is fitted with two three-screen Integrated Bridge Consoles providing embedded functionality to enable the execution of bridge operations and the monitoring and management of deck operations. Both IBS consoles are positioned at the forward part of the bridge to provide a wider field of view for the watchkeepers when seated at these positions during operations.

The bridge will typically be manned by four personnel. Operators have the ability to work in different modes and to call up various ship control information for display. They are able to carry out various duties from one position. For example, an operator is able to monitor the propulsion and engineering state or switch to the navigation and Electronic Chart Display and Information System display. There is also a chart table for manual chart work and a communications station.

A Dynamic Ship Control System combines maneuvering and monitoring functions into a one-man operation and provides automatic control (autopilot) capabilities for maneuvering the ship. The Ship Control Monitoring and Management System (SCMMS) enables positive control of ship propulsion and maneuvering from one location. At the same time, it provides monitoring and control of all propulsion, electrical, auxiliary and safety systems. The system works through an extensive network of sensors and closed-circuit TVs (CCTVs). By working on a common network, information is readily shared by the Machinery Control Room (MCR) with the bridge and the Combat Information Centre (CIC), enabling effective response to system failures and close monitoring of recovery actions. Not only can the bridge call up a feed of the situational picture from the CIC, it is also able to manipulate the picture from the bridge.

Management and control of all propulsion, electrical, auxiliary and safety installations is undertaken in the MCR. The SCMMS, operated primarily from the MCR, is able to continuously monitor and control the propulsion, maneuvering, electrical and auxiliary systems through dedicated workstations.

The management of fire-fighting and damage-control (FFDC) is also controlled from the MCR. The frigate is equipped with the Damage Control System enabling remote monitoring of fire detection and damage, and control over the operations of FFDC systems. This is achieved through an extensive network of remote sensors, CCTVs and actuators. Fixed fire-fighting systems such as sprinklers and FM200 can be remotely activated from the MCR. Information on FFDC can be updated electronically and distributed throughout the ship for greater situational awareness, responsiveness and decision making. Other measures to reduce vulnerability include the location of the CIC under the waterline in order to reduce susceptibility to single-hit incapacitation.

COMBAT SYSTEM

The frigate features an indigenously developed combat system known as the combat management system (CMS). The CMS is a federated system featuring embedded decision-support aids with an embedded weapons control function allowing for tighter integration with other ship sensors. A dual Fast Ethernet data-transfer system forms the information backbone for the combat system. The CMS provides automated functionality for sensor management, track fusion, picture compilation, threat evaluation and weapon assignment. As a federated system it is more vulnerable to battle damage than distributed systems such as the US SSDS system due to the fact that federated systems have nodes through which information pass through while fully distributed don’t – these nodes constitute points of vulnerability. Against this disadvantage, a federated architecture utilizes computing resources more efficiently and is less complex, resulting in savings in developmental time and money.

ST Electronics is providing the Standard Operating Common Consoles (SOCCs) for the CMS, which are installed in the below-decks CIC, the nerve centre for all combat operations within the ship. Operations within the CIC are grouped in clusters according to their combat roles and functions. Warfare supervisors manage operations within these clusters and are responsible to the principal warfare officers. Each SOCC features dual 20-inch colour flat-screen displays.

Another ST Electronics company, CET Technologies, is providing its SuperneT ST2600 Shipboard Integrated Communication System. ST2600 builds on the functionality of the earlier SuperneT ST2300 system but introduces Asynchronous Transfer Mode data networking for improved redundancy and resilience. The system provides control and management of all external communications (including satellite communications) together with internal communications and ship's broadcast.

France's BMTI has supplied the VHF/UHF antenna systems for the Formidable class frigates. Each frigate is fitted with two AS 329 UHF multisource (225-400 MHz) omnidirectional annular antennas, two AS 273 UHF broadband dipole (225-1,300 MHz) antennas, and three AS 262 VHF/UHF broadband dipole (110-500 MHz) antennas. Inmarsat B and VSAT satellite communication antennas are sited aft of the communications mast, with the VSAT antenna being the larger dome ‘buried’ within the superstructure, between the two exhaust stacks.

The frigates are envisaged as information nodes as well as fighting units. They will play the role of flagship in a naval taskforce, acting as the Republic of Singapore Navy's 'mobile ops centre' out at sea, with a span of influence that stretches up to about 200 miles. It will be capable of receiving information from sister ships and aerial assets deployed within that range. A recent exercise titled FLEETEX 2009 in the South China Sea on February 2009 involved all 6 Formidable class frigates, 3 Victory class missile corvettes, an Endurance class LST as well as AEW&C aircraft, fighters and maritime patrol craft from the RSAF. It was revealed that the Formidable frigate’s CMS could receive and fuse information from RSAF’s E-2C Hawkeye, F-50 Fokker MPA as well as Singapore’s land based radar network, allowing for the frigate to maintain silent operation without trading away situational awareness. During this exercise, the RSN also launched Boeing Insitu’s ScanEagle UAV from the helicopter decks of the frigate RSS Steadfast and the LST as part of a ship-based trial, suggesting a Level 5 UAV operation capability is under serious consideration/being added to the frigates. As a node in the network, the frigate is not just a mere recipient of information. With the received information as well as information obtained organically, it can make sense of the pieces of puzzle, establish an accurate picture of the area of operations and send the information back to shore and to its Army and Air Force counterparts. As such they are well equipped with communications equipment, and 5 consoles are reserved at the back of the CIC for that purpose.

One of the data communications systems the frigates are likely to be equipped with would be Link Sigma, a data-link deployed among the rest of the RSN fleet. It is a variant of the NATO standard Link 11, and its interoperability with other Link 11 users was demonstrated in exercise RIMPAC 08 when a common Link 11 network was set up with radar data contribution from Singaporean, Australian, Canadian, South Korean and US ships. Another data-link network likely to be used by the frigate would be Singapore’s indigenously developed ACCESS system, which is already installed on RSN’s Endurance class LSTs. According to US Navy news releases, it is a real-time, satellite based tactical communications system allowing for a common operational picture within RSN. A third possible tactical communication system would be the USN’s Combined Enterprise Regional Information Exchange System (CENTRIXS) which was also installed on the Endurance class LSTs. The frigate may have space and antenna allocated for the Portable Allied Command, Control, Communications Terminal (PAC3T) associated with CENTRIXS. The CENTRIXS is a secure communications system featuring real-time chat and email, and allows for a ship to share the sea situation picture with shore based headquarters, USN ships and other allied ships equipped with the PAC3T terminal.

RADAR

The Formidable frigate is equipped with the Herakles multi-function radar (MFR). It is a single-face, S-band mono-pulse hybrid active-phased-array radar with its passive beam-forming lens array incorporating 1,761 phase shifters. As such, it is able to form multiple beams concurrently as opposed to a single beam like other passive phased arrays. The entire radome, with the antenna unit inside, weighs more than 3,000 kg. The Herakles radar is optimised for the littorals and is intended to provide 3D air surveillance from 0 km out to a range of 250 km with coverage up to 70º. Surface range extends to 80 km, suggesting the ability to harness the surface ducting phenomenon in order to extend radar range beyond the horizon. The Herakles is housed in a low RCS radome which rotates at 60 rpm, and it has a track capacity of more than 500 air and surface targets. Peak radar power output is given as 50 kW. The high rotation rate of the radar has apparently caused unanticipated problems. A late modification to the Formidable-class frigate involved the addition of a platform under the rotating trapezoidal radar dome which was required to solve the air-flow problems encountered during the operation of the Herakles radar.

As a MFR it is capable of IFF, horizon scanning, environment mapping (ground and sea clutter, rain and jamming), accepting target cues from external sensors through the combat-management system, passive tracking of stand-off jammers, missile mid course guidance, gunfire control (through splash spotting), search and tracking. A Space Time Management (STM) device governs the signal generator for auto-adaptive radar scheduling to enable rapid switching between tasks and optimization of the time/energy budget in cluttered littoral environments. Simultaneous mid course guidance of up to 16 surface-to-air missiles is supported. With the Herakles combining both Search and Fire Control functions within the same radar (in a similar conceptual fashion to AEGIS) and the CMS featuring embedded weapons control function, one can expect a very short reaction time from target detection to launch of missile (probably in the order of single digit >=4 seconds compared to 15 to 20 seconds for many other systems).

The Herakles incorporates a number of advanced features. It is known to feature non-cooperative target recognition (NCTR) based on its use of a less than 1m resolution waveform, which allows for automatic classification of targets without relying on a cooperative IFF response from the target. This feature allows for faster reaction times which is especially important in the littorals. As a hybrid active-passive phased array radar, it features very low sidelobe emissions and is able to scan in both elevation and azimuth, allowing for very rapid transition from target detection to track initiation - track formation is completed within 1 second after initial detection for most targets, or within 2 seconds for highly stressing targets like incoming sea skimming anti ship missiles. Typical track formation ranges are given as 200 km on a fighter or helicopter, 60 km on a low RCS missile and 20 km on a sea skimming missile flying over rough sea. Volumetric search out to more than 200 km is done through a multi-beam approach which uses 4 concurrent beams produced from a 16-element 'retina' behind the lens to scan the airspace. To track targets and own-ship surface to air missiles a pencil beam is used as opposed to the usual track-while-scan used in other radars. Waveform optimization according to different environmental domains is also another notable feature of the Herakles radar.

The Herakles also features a high mean time between failure (MTBF) of 900 hours. Energy to the radar is generated by a set of 40 solid-state power modules (known as 'power books'). The radar enjoys graceful degradation of its performance - the loss of a few of these modules results in negligible performance degradation, with even a 50% loss of the modules leading to a mere 20% drop in radar range performance. Replacement of failed modules can be carried out without shutting down the radar. Unique to the Formidable frigate, there is also a dedicated local radar control workstation that is situated in the vicinity of the Herakles radar system. This is presumably a redundancy measure to reduce susceptibility to battle damage.

SECONDARY SENSORS

Secondary sensors on the Formidable frigate include 2 EADs NAJIR 2000 optronic directors for gun fire control. They are located above the bridge and the helicopter hangar for full 360º coverage, with each low RCS turret containing 4 sensors – a CCD TV sensor, 2 IR cameras (3-5 microns and 8-12 microns) and a laser range finder. Elevation limits are +85º /-35º, with a train rate of 120º/sec. 2 additional Terma Scanter 2001 I-band radars fill the surface search, helicopter-control and navigation roles. The Scanter 2001 features what Terma calls the Frequency Diversity Concept, which is based on simultaneous transmission on two different carrier frequencies. The effect of FD is touted as giving improved target detection on the basis of having two times power on target as well as the different reflection properties of targets under two different frequencies which can be exploited for clutter rejection. It is not known if the Scanter 2001 radar outputs are distributed to the CMS for track fusion.

The ESM suite has not been confirmed but is believed to be a variant of the Rafael Shipboard Integrated Electronic Warfare System (SEWS) comprising a radar-band electronic support measures (ESM) system and a multibeam jammer. No specific information has been released on the SEWS variant being supplied to the RSN. However, Rafael's most recent iteration of SEWS is understood to feature a 0.4-40 GHz C-Pearl ESM using digital receiver technology and a Shark electronic countermeasures subsystem based on solid-state transmitter technology. The latter is designed to counter multiple simultaneous threats using power management techniques and trackers.

What appears to be a biconical Adcock array has been placed atop the mast for a probable VHF/UHF direction-finding (DF) capability. This aerial may be part of a larger COMINT suite. This direction finding capability may also, if netted with similar arrays on other Formidable-class ships for triangulation to give emitter location, serve a targeting function for the frigate’s anti-ship missiles.

SONAR

The frigate is equipped with the EDO Combat Systems' Model 980 Advanced Low Frequency Towed Sonar (ALOFTS) variable depth sonar. The Model 980 uses the SQS-35 VDS body (less than 2.5 m long) and a AN/SQR-18 digital towed array combination which has been tested by the US Navy at tow speeds of over 30 kts. It provides 'under-the-layer' submarine detection and features long range detection with observed 1st and 2nd convergence zone detection capability. The ability to place the VDS under the thermal layer prevents rogue submarines from taking advantage of the thermal layer to close in onto the frigate without detection. The long range of the ALOFTS may also allow it to be utilized as a targeting sensor for the ship’s Harpoon missiles.

The ALOFTS towed body, deployed through an aft door using an automated launch, tow and retrieve system (LTARS) supplied by ODIM Spectrum, houses 18 flextensional transducers (nine on either side of the body) transmitting in the 1 kHz region at a 220 dB source level. The port/starboard transducer configuration allows high source-level directional transmissions to eliminate left/right bearing ambiguity. The fish is towed on a 200 m cable, with an additional 100 m tether to the acoustic aperture. The tail has a 60 m aperture (3X array, 2 kHz), which includes a torpedo detection segment. Due to the separation of transmission and reception, a benefit of this configuration is the ability to use very long and very wide pulses for greater processing gain in order to achieve increased detection probability without sacrificing short range detection capability. Broadband and/or narrowband passive detection operates concurrently and utilizes its own frequency band separate from the active bands, allowing the operator to rapidly analyze active contacts using the passive capability.

Inboard, ALOFTS consists of two electronics cabinets (separate transmitter and processor enclosures). According to EDO, the functionality offered by ALOFTS includes coherent digital signal processing for frequency modulated (FM), continuous wave (CW) and combined FM/CW waveforms for active panoramic or sector search. Other features include non-coherent echo combining for sequential transmissions, automated operator assistance for extraction of submarine-like targets, passive broadband detection, multitarget tracking, tactical geographic displays, a 12-ping history, automatic torpedo detection and alerting, false-alarm/-reverberation reduction and performance prediction. Optional features which may have been incorporated into the frigate include passive broadband search and track, passive narrowband search and track, passive classification using LOFAR, DEMON and an onboard trainer.

Displays include 12 ping history active search and expanded zoom formats for each preformed beam, target classification aids assistance for extraction of submarine-like targets, passive narrowband, passive broadband bearing/time history and tactical (geographic) format. Display overlays are provided for performance prediction, bottom topography and landmass outlines. The tactical display is formatted to easily interface to other onboard or offboard sensors using standard symbology. Full azimuth coverage is provided in broadband and narrowband.

MAIN GUN

The frigate is armed with a single Oto Melara 76mm Super Rapid in a stealthy gun mount. The ubiquitous gun gives the Formidable-class frigate a versatile punch. The Super Rapid is a significantly redesigned version of Oto Melara’s earlier 76 mm Compact gun, and it was designed with the anti-missile role in mind. Hence it features a high rate of fire of 120 rnds/min, and a firing rate of 139 rnds/min was achieved during tests. Accuracy has also been improved, with dispersion now reduced to 0.3 mrad at 1000 m (many small caliber close in gun systems have greater than 2 mrad dispersion at similar ranges). Mount training rate is given as 60º/sec, while elevation rate is 35º/sec. Elevation limits are +85º/-15º, with full 360º traversal. The mount comes with an 80 round ready ammunition capacity. Expected anti-cruise missile engagement range is 6,000 m, with first rounds arriving in the vicinity of the inbound missile at around 5,500 m. Maximum range against surface targets using standard munitions is 16 km.

The multirole Oto Melara munitions (MOM) can be used against aircraft and anti-surface cruise missiles, as well as for shore bombardment. The 6.35 kg Semi-Armor-Piercing Oto Munition (SAPOM), which has a delayed-detonation impact fuze, is designed for use against surface ships. The Semi-Armor-Piercing Oto Munition, Extended Range (SAPOMER) is similar to the SAPOM, except that the reconfigured shell is somewhat larger and heavier at 6.5 kg. Maximum range achievable with this round is 10.75 nm (20 km). The SAPOM and MOM are confirmed to be in RSN inventory.

A new 5 kg lightweight round designated AMARTOF (anti-missile ammunition, reduced time of flight) has been designed by Oto Melara for a dedicated anti-missile role. The new round's pre-formed fragmentation (PFF) casing has the same external ballistic configuration as the earlier SAPOMER round, and is fitted with a base-drag reduction device in the tail. It is filled with pre-formed tungsten cubes as opposed to the spheres used in earlier shells, giving the new shell a lethal radius of 10 m. The total weight of tungsten fragments produced is 2.7 kg; the fragments have a velocity of 1,650 m/s when employed against a target flying at 300 m/s. The explosive is initiated by a new-generation miniaturized millimetric-wave proximity fuze. In addition, the energy of the propelling charge has been increased. AMARTOF's lower mass, higher initial velocity (1,100 m/s) and lower velocity-drop give a 40% reduction in time of flight out to 6 km compared with the earlier OTO Mod.84 and MOM (Multi-purpose OTO Melara) PFF rounds. Projectile time of flight is 3 seconds to 3,000 m and less than 8 seconds to 6,000 m.

SURFACE TO AIR MISSILES

The frigate uses the Aster missile in conjunction with the Herakles radar system. The Asters are stowed in 32 Sylver cells. With the Sylver launcher having limitation of a 150 ms interval between each firing, the rate of fire (ROF) for the Asters is 6 rnds/sec. While many sources attribute the Formidable frigate with a loadout of 32 Aster 15s in 4 octuple A43 VLS modules, this information is now suspect. In 2002, DCN claimed that 12 launchers of the A50 version were bought for at least one unidentified export program outside Europe. Only two customers for the Sylver system existed outside Europe at the time - Singapore and Saudi Arabia. With Saudi Arabia’s 3 F3000S Sawari class frigates equipped with 2 A43 modules each, it is unlikely that Saudi Arabia is the customer for the 12 A50 modules in question, which in turn means that Singapore’s 6 Formidable frigates are the likely recipients with 2 A50 and 2 A43 modules in each frigate. Furthermore, in an article Jane's claimed to have accessed material suggesting that Project Raven - the internal MBDA codename given to the Singaporean programme - included the capability to fire the longer-range Aster 30 missile. With the A50 module only able to support the Aster 30 and Aster 15, it can thus be assumed that the Formidable can hold a mixed load of up to 16 Aster 30s with the remaining cells holding Aster 15s for a total of 32 Asters. This would make the RSN the first South East Asian country to acquire an area air defence capability.

The Aster missile family uses a common second stage but different boosters to meet separate roles. The second stage is called a "dart". The Aster "dart" is a long, slim cylinder with a sharply pointed nose. It has four slim, narrow chord wings in cruciform configuration and cropped-delta tail fins. The booster is faired into the "dart" body and has a broad cylindrical shape with large cropped-delta fins. Upon launch, the Aster 15 achieves its terminal velocity of M3.0 in 2.5 seconds while the Aster 30 reaches a terminal velocity of M4.0 in 3.5 seconds. Average speed of the Aster 15 and Aster 30 is 800 m/sec and 950 m/sec respectively. The Aster 15 has a maximum range against supersonic sea-skimming targets of up to 6.5 nm (12 km), 9.18 nm (17 km) against supersonic fighters or subsonic sea-skimmers and 16.2 nm (30 km) against subsonic aircraft. The comparable figures for Aster 30 are 18.9 nm (35 km), 27 nm (50 km) and 64.8 nm (120 km). Minimum ranges for the Aster 15 and 30 are 1.7 km and 3 km respectively. With the low minimum range of the Aster 15 (which is nearly the minimum keep out range of a subsonic missile), the need for a CIWS has been correspondingly reduced.

The Aster houses a MBDA AD4A Ku-band (1.6 to 2.5 cm, 12 to 18 GHz) (NATO J-band, 10 to 20 GHz) active pulse-Doppler radar seeker with high-power traveling wave tube transmitter and wide antenna deflection. The programmable AD4A is reported to be capable of home-on-jam. After firing, the seeker is switched on at a predetermined point and is laid using data provided through the uplink. Once achieving lock on, the terminal phase is conducted autonomously with the target being attacked from above whenever possible.

The Aster carries a 10 to 15 kg focused HE blast fragmentation warhead behind the equipment bay. The warhead is fuzed by a Ku-band RF proximity fuze which produces a CW pseudo-random phase digital coded waveform. Maneuverability is a key element in Aster performance and is based upon the PIF thrust vector control to reduce reaction times and lateral acceleration with maneuvers up to 12 g and Pilotage Aerodynamique Fort (PAF) using the traditional method of aerodynamic surfaces to provide maneuvers up to 50 g, giving total maneuverability of more than 60 g. PIF is used just before impact, so that even supersonic (Mach 2.5) targets performing up to 15 g evasive maneuvers may be successfully destroyed with a hit-to-kill capability with a miss distance of <2 m.

While the Aster missile system accrues maneuverability advantages from its lightweight ‘dart’ second stage, it pays for the additional maneuverability by sacrificing warhead size. With its meager warhead of 10 to 15 kg there is a consequent loss in its effectiveness when conducting surface attacks that similar missiles such as the ESSM and SM-2 are able to perform, though it’s high supersonic capability mitigates that somewhat. Indeed, no anti-surface capability has been mentioned for the Aster, and it is unlikely to ever be regarded as being able to satisfy that role satisfactorily even if an anti-surface capability existed.

ANTI-SHIP MISSILES

The Formidable frigate’s main surface warfare punch lies in it’s battery of eight Harpoon Block 1Cs housed in two quadruple canisters. The Harpoon is a subsonic sea-skimming anti-ship missile system capable of Mach 0.75 flight. Upon launch, the Harpoon missile flies ballistically to a height of 700 m, then transitions to sea-skimming mode for low level flight all the way to its target. It incorporates a high explosive warhead weighing 221.86 kg with contact, proximity or delay fuzing. In the Block 1C version, Boeing incorporated programmable waypoints which permit the missile to approach its target indirectly (performing dog-leg turns to conceal its launch platform). Other improvements include a 15 percent improvement in range to 67 nautical miles (124 kilometers), a 100 percent increase in the onboard computer memory, and an enhanced sea‑skimmer capability (the missile flies at a 50 percent lower altitude compared to earlier versions). Currently, Harpoon is credited with an operational reliability of 93%.

During the Naval Platform Technology Seminar held in Singapore in 2004, Singapore’s Permanent Secretary (Defence) Peter Ho hinted that the Harpoon missile was considered an interim fit, stating that,” these third-generation platforms (Formidable class frigates) must eventually be upgraded and armed with a new generation of anti-ship missiles that can defeat the most advanced defences".

Ho continued: "Like other navies, the RSN will have to look ahead to future anti-ship missile systems and one promising option is the supersonic anti-ship missile [but] it will need an additional capability to discriminate legitimate targets against the cluttered background of one of the busiest shipping lanes in the world."

DECOYS

For soft-kill defence, each ship is fitted with the EADS Defence Electronics New Generation Decoy System (NGDS) with two trainable eight-barrel 130 mm launchers fitted forward of the bridge. Early plans and even the first of class, the Formidable, entered service with a third launcher mounted on the hangar roof aft. However, after further evaluation it was found that the two forward launchers were sufficient and thus the third launcher was not installed in subsequent ships and were deleted from the Formidable as well, this being visually confirmed during IMDEX 2009. The launchers have been designed with inclined sides to reduce RCS. NGDS offers confusion, dilution, distraction/active centroid reduction modes when used in stand-alone mode, and dump seduction when used with an onboard jammer. The effectiveness of the decoys in all modes is greatly enhanced with Formidable frigate’s low RCS design. In the torpedo defense role it can use decoy and jamming technology even against incoming weapons. An active decoy known as SEALAD is also under development for the NGDS.

NGDS uses Special Advanced Lacroix Electro-Magnetic (SEALEM) RF, Spectral Advanced Lacroix IR (SEALIR), Seaborne Multi-band Optronic Screening (Seamosc) and Seaborne Lacroix Anti-Torpedo (SEALAT) munitions from Etienne Lacroix. SEALEM replaces 2D chaff and is said to be much more representative of a 3D structure by simulating ship parameters such as RF polarization, spectral fluctuation and even platform area and depth. Coverage is omnidirectional with a tailorable 33-42 dB/m2 effect in the 2-36 GHz band. It can be used for centroid seduction (40 sec duration, 200 m range, <150 m initial height), distraction-seduction (40 sec, up to 1,800 m range, <150 m initial height), dilution (<190 sec, 2,250 m range, <700m initial height) or confusion (<190 sec, up to 8,000 m range).

SEALIR offers a spectral pyrotechnic composition payload that produces a single-cloud, multiband response which offers a combined low level near-IR, ship level mid-IR (ship's funnel) and large area far-IR (ship's hull) signature. Like SEALEM, it can be used for centroid seduction (40 sec duration, 200 m range, <150 m initial height), distraction-seduction (40 sec, up to 1,800 m range, <150 m initial height), dilution (<190 sec, 2,250 m range, <700m initial height) or confusion (<190 sec, up to 8,000 m range).

SEALAT generates a high intensity acoustic signal in the low frequency band from several hundred Hz to 65 kHz. The rugged effector can be deployed in the close vicinity of the ship as well as at long range and has an effective duration of up to 10 minutes. It is available in two operating modes: in a straight jam mode close in; or deployed by rocket out to a range of 2,000 m from the ship in a decoy mode. It is claimed to overcome some of the potential risks associated with towed jammers, which could, for example, act as a beacon signal for wire guided torpedoes to home in on.

TORPEDOES

Hidden behind bulwarks is one B515 triple-tube launcher located on each side which fires Eurotorp A244/S Mod 3 lightweight torpedoes. Singapore was the first customer for the Mod 3 version. The A244/S Mod 3 version was announced in 1998 and it incorporates some MU 90 Impact torpedo technology. Compared to earlier versions, it has a new seeker, new software, a new battery (silver chloride magnesium alloy compared to the former lead acid battery) and a new dual speed motor. Brochure figures give a maximum speed of 38 knts with a corresponding range of 10 km. Average speed at high speed setting is 36 kts and 30 kts at a low speed setting with a corresponding range of 13.5 km. The A224/S Mod 3’s operating depth is 30 m (minimum pull out depth) to 600 m, with the ability to function in waters as shallow as 10 m. Warhead composition is HBX-3, with warhead weight given as more than 42 kg.

The seeker uses 36 transducers to produce 10 transmitting and 8 receiving preformed beams over 6 frequencies and covers a 80 x 40 deg field of view (FOV). The full FOV is scanned every 2 seconds. The seeker combines narrow and broadband operation, and it operates in active, passive or mixed modes, with multiple time/freq (FM/CW) transmitting codes. Seeker acquisition range is given as 2,150 m in active mode and better than 2 km in passive mode, with the ability to detect static and moving targets. It uses a self-adaptive detection threshold, classifying targets using a 12 level scoring system. Ability to detect anechoic covered submarines and a sophisticated acoustic counter-countermeasures capability is also claimed by the manufacturer.

AVIATION FACILITIES

Aviation facilities aft provide for the operation and support of a Sikorsky S-70B Seahawk helicopter, 6 of which were ordered in 2005 for delivery in 2009 and 2010. Aeronautical & General Instruments (AGI) has supplied its AGIMET wind and meteorological measurement system, comprising two ultrasonic wind sensors, a temperature sensor, a barometric pressure sensor, a humidity sensor, a motion reference unit and multifunctional colour repeaters, to support flight-safety management.

AGI is also providing its HELIVAS (Helicopter Visual Approach System) suite of visual landing aids to the Formidable-class frigate programme, comprising a stabilized glide slope indicator, a stabilized horizon reference system, and a pilot visual-cues system (used in conjunction with Indal Technologies' Aircraft Ship Integrated Secure and Traverse [ASIST] entrapment and handling system). HELIVAS is also compliant for use with night-vision devices in order to provide pilots with clear and unambiguous signals of the correct approach flight path, ship's motion indication and defined area for landing during both day and night operations.

ASIST is a lightweight, fully integrated 'wireless' system. Using ASIST, helicopter landings are made solely by the pilot, during a quiescent period in ship motion. During descent, ASIST's precision helicopter position sensing equipment system continuously tracks and monitors the exact position of the aircraft, relative to the designated landing area and displays it to the pilot through a series of visual landing cues.

Guidance data is simultaneously relayed to a computer-controlled Rapid Securing Device (RSD), which automatically moves fore and aft along the flight-deck track to maintain its position directly beneath a probe on the underside of the helicopter. Immediately upon touchdown, the probe is secured by the RSD, and the aircraft is ready to be aligned and traversed into the hangar.

S-70B HELICOPTER

Not much information has been revealed about the S-70B’s mission suite. Footage released in the 40th RSAF anniversary CD shows what appears to be RSAF’s S-70B Seahawk, and it can be visibly confirmed that the S-70B mounts a FLIR in front of its nose. An APS-143 radar is located beneath the cockpit, and a 4 rack M299 launcher was mounted underneath the pylon on the port side of the helicopter. This probably indicates the ability of the Singapore’s S-70B configuration to launch Hellfires which are already in RSAF inventory.

When queried on the likely mode of operations of the Seahawks when they enter service on the frigates, it was stated that the Seahawks would likely follow the US method of operation whereby the Seahawks would be an extension of the ship’s sensors; with the ability to download the information from each of the Seahawks sensors directly to the combat management system via a dedicated feed but control (down to the helicopter’s sensors) coming from the ship. This is as opposed to the Royal Navy’s model of operations whereby their Merlins conduct the required processing onboard; with an onboard commander directing the ASW fight and vectoring in Sea Lynxes to prosecute any targets found. In any case confirmation would be provided when the Seahawk is unveiled with a TCDL is found on the Seahawk, and modifications to the ship’s mast are made to incorporate the required datalink.

S-70B HELICOPTER – SONAR

The only confirmed information on equipment type so far has been the purchase of the APS-143 radar and the Helicopter Long Range Active Dipping Sonar (HELRAS) DS-100 dipping sonar for the S-70Bs. Similar in size and weight to L-3 Ocean Systems’ widely sold mid-frequency AN/AQS-18(V) dipping sonar, the HELRAS is a high source level (218 dB/meuPa/yd) LF sonar operating at 1.31-1.45 kHz with a FM bandwidth of around 300Hz. Compatible operating frequencies with the ALOFTS sonar on the frigate opens up the possibility of HELRAS being used to provide a bistatic operating capability (or a multistatic capability allied to passive sonobuoys dropped by maritime patrol aircraft). The DS-100 employs a unique transducer design (LF flex disc technology) in the transmit array to provide extremely high acoustic power levels in a lightweight array. The high-efficiency vertical line projector radiates in a narrow beam to reduce boundary interaction and couple efficiently into long-range propagation modes. The highly directional receive array discriminates against noise interference and provides maximum sensitivity of the return echo for high detection ranges. The transmit array has eight projector elements (including an underwater telephone transducer), which together form a vertical array, 5.2 m long, let down from within the wet-end central body during deployment. The beam can be transmitted from -15º to +15º in elevation and through 360º in azimuth.

The dipping sonar is capable of reaching depths of up to 500 m, with the advanced reeling machine is evolved from the field-proven AQS-13/18 series. It allows automatic deployment and retrieval of the wet end to depths substantially below the deepest mixing layers for detection of the deepest diving submarines with minimum dip cycle time. Wet end lowering and raising rates are given as 2.l m/sec and 4.6 m/sec respectively. The wet end contains a high-capacity battery that provides primary power for active transmission and array deployment/retrieval. The battery is charged between transmissions via the cable. This configuration provides improved power efficiency and allows safe recovery. The dome control commands remote deployment and retrieval, and continuously monitors the wet end status. Cable angle and cable payout signals are provided for the automatic flight control system to maintain helicopter position over the array during hover.

The sonar's low frequency transmission/receive characteristics are optimised for extremely long ranges in shallow water. The low frequency minimizes multiple boundary interactions and reduced reverberation interference for the received signals. Range scales are graduated between 1, 1.5, 2.5, 4, 6, 10, 16, 25, 40 and 60 nm. Range accuracy is given as <2% of range scale, and bearing accuracy is given as 2º. Operating modes include active CW to l0 sec pulses (FM to 5 sec pulses), passive and underwater telephone. CW pulse transmissions are used for long-range detection in the sonar convergence zone, with FM and short CW pulses employed for target re-acquisition, location and attack. Use of high resolution Doppler processing and shaped pulses enables detections of targets even at speeds below 1 kt, according to L-3. Extended duration FM pulses are additionally available to detect the near-zero Doppler target. Up to 10 targets can be tracked simultaneously. Active display formats comprise: all beam Doppler range; bearing-range/Doppler-range; bearing-range; and A-scan. Total weight is 326 kg, including 152 kg for the wet end, 115 kg for dome control, reeling machine, reel and cable, 45kg for the processing electronics and 14 kg for the sonar control and flat-panel display.

The acoustic interface unit has powerful signal processing algorithms specifically designed to take advantage of the wide area search capability of the HELRAS DS-100. The unit performs demultiplexing, beam-forming, and signal processing functions, and provides an output for presentation on the aircraft display. Reverberation suppression techniques such as manipulation of waveform design of the transmitted pulse, Doppler filtering, ping-to-ping analysis and analysis of the pulse length in space or time, make the sonar suitable for shallow water operations.

The HELRAS has a second convergence zone capability under optimum conditions; it has demonstrated ranges of 30 km to 70 km in the Tasman, Ionian and Ligurian Seas. During trials in the Timor Sea, it achieved a range of 50 km in water depths of 100 m; it has functioned in water depths as shallow as 50 m. HELRAS has also demonstrated effective performance in the Norwegian fjord by overcoming the reverberation effects of the sheer walls. During an exercise in 1995, the Italian exploited the sonar’s very long range by using HELRAS equipped helicopters as a form of underwater AWACS, vectoring in helicopters equipped with short-ranged dipping sonars. As part of the US Littoral Combat Ship development effort, the HELRAS was tested in the Sea of Japan during trials from August to September 2004 where it was deployed from an 11 m RHIB boat; results showed the HELRAS typically tracking a diesel submarine to 22 km, a figure limited by local conditions.

L-3 states that the system has “a figure-of-merit sufficient to achieve convergence zone detections in deep water, and transmission/ receive characteristics optimized for extremely long ranges in shallow water,” adding: “In addition to HELRAS’s long range surveillance and search capability; it is also well suited to redetection, target localization and weapon delivery against deep and shallow water targets.” The company further claims that results from tests conducted by the US Navy; the Royal Australian Navy, the Italian Navy and the Royal Norwegian Navy in waters ranging from the Timor Sea, Mediterranean, to the Vestfjorden have demonstrated HELRAS ‘outperforming even ship-borne systems against diesel-electric submarines”.

S-70B HELICOPTER – RADAR

The specific variant of the APS-143 radar ordered from Telephonics in 2006 and installed on the helicopters has not been disclosed. The APS-143 encompasses a family of radars of varying performance for different platforms. However, given the order date of the radars and that the (V)3 model is for helicopters, the model ordered is likely to be either the APS-143B(V)3 or the APS-143C(V)3, more likely the latter. Both the APS-143B(V)3 and C(V)3 variants contain improvements derived from the APS-147 radar fitted on MH-60R Sea Hawks. The more advanced, low probability of interception (LPI) APS-147 is understood to be non-exportable at the moment. The APS-143B(V)3 model works in X-band (9.25-9.70 GHz, 460 MHz agility), with a peak power output of 8 kW and an average power output of 280 W. The claimed range performance of both models are similar – maximum range is given as more than 370 km. More specifically for the B model, claimed performance is a detection range of >37 km range on a 1 m2 target in sea state 3. Other performance values are also similar between the two radars, with both weighing 82 kg. The antenna is stabilized from -25° to +10° in pitch and roll, with a sector scan capability in a 45° to 350° sector (operator selectable) and full 360°. Azimuth accuracy is 0.5° or better, and search range resolution is <3 m. Manufacturer claims that this performance is 5 times better than that of standard maritime radars. Display range resolution is 20 m; 1 m for imaging.

APS-143B(V)3 standard operating modes comprise:

-standby (antenna rotates but does not transmit)
-long-range surveillance search 100/200 (large sea surface detection, slow scan speed, low Pulse Repetition Frequency (PRF) and wide pulse transmission)
-short-range search 25/50 (search and rescue/return-to-ship/helicopter oil platform landing applications, short unmodulated pulse)
-weather avoidance (operator selected, four colour return video processing for optimised storm detection)
-beacon (interrogates International Telecommunications Union (ITU) standard Search and -Rescue Transponder (SART) beacons and displays the replies, 9,375 MHz transmission, 9,310 MHz reception)

APS-143B(V)3 optional operating modes comprise:

-imaging (Synthetic Aperture Radar and Inverse Synthetic Aperture Radar (SAR/ISAR), pulse compressed)
-range profiling (A-scope presentation (signal intensity verses range), staring (10 Hz image updating) and rotating (scanning antenna rotation rate) modes)
-ISAR (continuous, 2-D image (range verses cross-range) of a surface strip illuminated by the real antenna beam, multiple swath sizes and resolutions supported)
-spotlight SAR (continuous, 2-D image (range verses cross-range) of a fixed spot illuminated by the real antenna beam, 1, 2, 4 and 8 m resolution supported, generates a 2 Hz rate 'movie' of the desired target).

As of 2006, APS-143B(V)3 growth and planned modes comprised:

-air-to-air (growth, Moving Target Indication (MTI) Doppler processing)
sea MTI (growth)
-Identification Friend-or-Foe (IFF) interrogation (planned)
-oil slick detection (planned, vertically polarised antenna preferred)
-single channel Ground MTI (GMTI, planned)
-multiple channel GMTI (planned).

Unmanned Aerial Vehicle (UAV)

The ScanEagle UAV is a long endurance UAV featuring endurances of more than 15 hours, with the later Block D version featuring more than 28 hours of endurance upon conversion to using JP-5 fuel. It has a cruise speed on 25 m/s and a max level speed of 36 m/s, with a flight ceiling of 5,950 m. For a long endurance UAV, it is relatively small with a wingspan of only 3.1 m, and a length of only 1.78 m. It is also relatively stealthy, being silent when operated above 1,000 m. A noise muffler is available for installation. For storage, it is dismantled and packed into a storage box of dimensions 171×45×45cm.

The standard payload until 2006 comprised either an EO or an IR camera in a gimballed and inertially stabilised turret; the EO camera has ×25 zoom, the IR camera had an 18° FoV and ×2.5 fixed zoom. In August 2006, as part of the Block D reconfiguration, Insitu completed an upgrade to the sensor turret enabling it to house larger cameras. The IR sensor was replaced by a new DRS Technologies E6000 unit offering ×7.5 digital zoom and enhanced resolution, and a Mode C transponder was added to allow for utilisation of the UAV into civilian airspace. The EO payload is now aligned to GPS, and features image-based object tracking.

A multitude of other payloads are available or under development, with the USN intending to incorporate a Magnetic Anomaly Detector (MAD) into the ScanEagle. Another significant addition to the ScanEagle would be the incorporation of Automatic Identification System (AIS), allowing for interrogation of the identity of AIS equipped surface vessels, thus greatly improving the ship’s Over The Horizon (OTH) situational awareness. Other sensors being considered include biochemical sensors, the NanoSAR miniature synthetic aperture radar and laser illuminators. A high-speed wireless communications relay (voice and video) was also successfully demonstrated in December 2004.

Launch of the ScanEagle UAV is via a SuperWedge Launcher weighing 589 kg. It measures 4.9 m in length when stowed (6.4 m deployed), and a width of 1.3 m. It requires 2 men to move and 10 min to setup. Recovery of the UAV is carried out via a patented Genie Skyhook Recovery system, and this is what sets the ScanEagle UAS apart from many other UAS in allowing the fixed wing UAV to be recovered at sea. During recovery, the ScanEagle UAV flies into a single line suspended over the water from a 15.2 m (50 ft) boom. A hook on the wingtip then engages the line to arrest the aircraft for retrieval. The Skyhook Recovery system weighs 1,585 kg, with a length of 5.5 m and a width of 1.5 m. It requires 2 men to setup, with setup and breakdown time being 30 min and 20 min respectively. Both launch and recovery operations are limited to wind conditions of below 30 kts. Given the size of the launch and recovery equipment, it might be possible that they will displace the helicopter when embarked.

Guidance and control of the ScanEagle is carried out via a UHF (900 MHz) datalink and S-band (2.4 GHz) video downlink, giving a maximum operating radius of up to 100 km without using communications relay node. The Ground Control System (GCS) has two consoles, each able to control up to four air vehicles. Athena GuideStar GS-111m DGPS waypoint navigation and autonomous object tracking was used initially, but new software demonstrated in March 2005 enabled the ScanEagle to map its route autonomously while in flight and to complete a series of unspecified maneuvers. A picture accompanying a Straits Times article on the FLEETEX 2009 revealed a dish antenna in place of the former rear decoy launcher over the hangar, and this is likely to be the datalink telemetry antenna supporting UAV operations.

Boeing Insitu’s ScanEagle was trialed from the RSS Steadfast and one of the Endurance class LSTs during RSN’s FLEETEX on February 2009. The UAV was launched at night. During the flights, the ScanEagle UAS successfully demonstrated sea-based launch and recovery capabilities and the ease with which the physical ground support equipment and control hardware can be integrated onboard. All tactical objectives and operational scenarios set for the flights were achieved. Boeing Defence Australia provided a complete maritime ScanEagle system for the trial, including a ground control station, communication links, launcher and SkyHook recovery system. A Boeing Insitu team deployed to Singapore for the entire trial.




Last edited: 28/06/09