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Monday 25 May 2015

Sachsen class frigates of the German Navy

Written by D-Mitch

Frigate Hessen, last ship of the Sachsen class.
The Sachsen class (or else F124 class/Klasse 124) of German Navy (Deutsche Marine) is a class of three high-tech Anti-Aircraft Warfare (AAW) frigates built by Blohm + Voss, Howaldtwerke-Deutsche Werft and Thyssen Nordseewerke (from 2005 the three companies are part of ThyssenKrupp Marine Systems) the period 1999-2005 under a contract of €2.1 billion (!) that was signed in 1996. The shipyards joined forces for this contract as Working Group 124 (ARGE 124); all three yards built a vessel each. An option on a fourth vessel that was provisionally to have been named Thüringen was not taken up. This class of warships is based on an enlarged pattern of the Brandenburg class (F123/Klasse 123) multipurpose frigates featuring stealth characteristics, weapons and sensors for air defence capabilities. The three vessels replaced the three Lütjens-class destroyers that were modified Charles F. Adams-class destroyers. It is worth of mention that the ships of the class have about 2,000tons more displacement and 10 meters more length than the class that they replace. The Sachsen class frigates are very similar to the Dutch De Zeven Provinciën class frigates (the class will be analyzed in another article), in that both are based on the use of a common primary anti-air warfare system built around the APAR and SMART-L radars as well as the area-defence SM-2 Block IIIA and point/medium range defence Evolved Sea Sparrow Missile (ESSM) surface-to-air missiles. The ships of De Zeven Provinciën class frigates are of similar size but their major differences are that they have one more module (8-cells) in their vertical launch system (VLS), they have Goalkeeper CIWS instead of RAM, 5in gun and their hangar can accommodate one helicopter. The last ship of the class, Hessen, entered in service in April 21, 2006. The vessels of the class are some of the most advanced AAW in the world and contribute significantly to the European air-defence.

The three frigates of the Sachsen class in formation.
The general characteristics of the class is a displacement of approximately 5,800tons at full load, length of 143m, beam of 17.4m, maximum speed of 29 knots and a range of 4,000n.m. with the speed of 18 knots. The crew is about 240 while there are additional accommodations for a squadron commander's staff. Furthermore, the ships were designed with a capacity for an extra 270 long tons (270 t) of weight, to allow for future additions of new weapons and sensors without compromising the ships' efficiency. The propulsion system is Combined Diesel and Gas (CODAG) with a gas turbine and two diesel engines. It takes less than a minute to start the gas turbines, and within two minutes the ship is at full speed.

Modified photo of a Sachsen class frigate. For a high resolution image click here.
OTO Melara 3in of frigate Sachsen.
OTO Melara 3in of frigate Sachsen.
Photo: Arnekiel
The ships are equipped with the standard OTO Melara Compatto 3in (76.2mm) fully automatic gun installed forward of the bridge. The gun has excellent performance in any kind of role, such as air-defence, anti-surface, anti-missile and shore bombardment role. It can hit surface and air targets at a distance of 4 km (at 85 degrees) and 16 km (effective 8 km) respectively with a rate of fire 85 (100 rounds per minute with a retrofit kit; German Navy has installed this kit on its guns) and weight of shell greater than 6 kg. There are 85 ready rounds on the mount. Strangely enough, German Navy did not proceed with the purchase of the Super Rapid variant with the increased rate of fire. It is rumored that the 3in gun will be replaced by the new OTO Melara 127/64 LW - Vulcano system which is being installed on the F125 class.

Frigate Sachsen, lead-ship of the German F124 class.

MONARC on frigate Hamburg
MONARC on frigate Hamburg
A KMW PzH 2000 (Panzerhaubitze 2000) howitzer turret with a 155mm (6.1in) gun was mounted on the deck of F220 Hamburg as a demonstration of the feasibility of the system for naval applications in 2003. Live fire trials were conducted in September 2003. The concept was called MONARC (modular naval artillery concept) and requires a flexible elastic mounting. MONARC had a range of 41km and a rate of fire of 10rds per minute. Special ammunition could extend the range to 80km. While an intricate elastic mounting system handled the recoil, adapting all of the PzH-2000’s systems for the corrosive naval environment proved more difficult than expected and MONARC has been removed from plans for the F125 class frigates which will receive the new OTO Melara 127mm.

Frigate Hamburg of German Navy
Frigate Hamburg. Photo: Bundeswehr Marine
MLG 27 of frigate Sachsen.
Elements of MLG 27
Each vessel of the class is equipped with two Rheinmetall MLG 27 RWS (Remote Weapons Systems). Short for "Marineleichtgeschütz 27mm" (light naval gun), the MLG 27 is the naval version of the 27 mm BK 27 aircraft gun used on the Tornado and Gripen fighter aircraft. This weapon is a gas-operated automatic revolver cannon. Based on the high rate of fire BK27 revolver cannon (up to 1,700 rounds per minute!) it enables effective engagement of fixed wing aircraft, helicopters, speedboats and land based targets. The system is particularly suitable for defending against terrorist attacks involving high-speed craft. The MLG27 features an integrated EO sensor package from SAM Electronics (previously known as STN Atlas Elektronik) with TV camera, thermal imager, laser range finder, tilt sensor, stabilized mirror system and video tracking system for automatic and manual target tracking. It is interfaced with existing ship systems and it can be operated remotely or locally with a joystick. The MLG27 design allows integration in all kinds of vessels without the need for deck penetration. The system has a maximum range of up to 4,000m and while the effective range is close to 2,500m. The system can receive a wide array of modern medium caliber ammunition, including Frangible Armour Piercing Discarding Sabot (FAPDS), Frangible Armour Piercing (FAP), target practice (TP) and PELE (Penetrator with Enhanced Lateral Effects). Watch a video of the gun system while its firing here.


Except the guns, the ships are equipped with a combination of heavy machine guns (M2HB of 12.7mm) or light machine guns (MG3 of 7.62mm). The M2 has a maximum (effective) range of around 1,830m and a cyclical rate of fire of approximately 600 rounds per minute. The Rheinmetall MG3 7,62mm light machine gun has a rate of fire 1,000-1,300 rounds per minute and an effective firing range close to 1km.

MG3 on Sachsen class frigate (helipad)
M2HB mounts on Sachsen class frigate

MG3 on Sachsen class frigate (bridge)
M2HB on Sachsen class frigaate

Harpoon launchers of frigate Sachsen. Photo: Emmanuel L.
Each frigate carries eight (8) Boeing RGM-84D Harpoon anti-ship missiles in two Mk141 quad launchers amidships. These missiles have a range greater than 120km, a sub-sonic of speed of 860km/h (Mach 0.9) while they carry a warhead of 221kg. Harpoon missile has a low-level, sea-skimming cruise trajectory, active radar guidance and it is capable to perform pop-up manoeuver which it is a rapid climb of the missile to about 1,800m before diving on the locked target. Once the target is detected, the missile approaches this in a flight height of 2 to 5 meters until impact. The warhead does not discharge directly on impact, but with a time delay, so that the explosion takes place inside the ship and significantly more damage than at a contact igniting weapon. The Harpoon launchers will be replaced in the near future by the KDA Naval Strike missile (NSM).

Harpoon launchers of frigate Sachsen. Photo: arnekiel
Frigate Sachsen. Photo: Jan Czonstke

The Mk 41VLS of Sachsen.Photo: arnekiel
MK 41 VLS of frigate Sachsen behind
the Mk 49 GMLS (RAM)
The anti-aircraft protection of the ships is based on a Vertical Launching System, (VLS), the Raytheon Mark 41 (Mk 41). This launching system is located behind the RAM launcher and before the bridge, and consists of four modules with eight (8) cells each ( total 32 cells). The 32-cells can be equipped with surface to air missiles of the type SM-2 Block IIIA (RIM-66M-2) and RIM-162 Evolved Sea Sparrow Missile (ESSM). The SM-2 missiles are loaded one per cell while the ESSM are loaded in guad-packs per cell. The usual configuration of the load per ship is 24 SM-2 and 32 ESSM. The SM-2 Block IIIA has a range of 167 km and reaches a speed of Mach 3.5. The ESSM can reach 50 km range with a speed of Mach 4 while its  maneuvering capability reaches the 50G (!) giving an excellent capability to the missile to counter supersonic maneuvering anti-ship missiles. The warhead of ESSM is of 39kg. Both missiles are dependent on the APAR for target illumination on final approach, since they are guided by semi-active radar homing. As part of the Study "Capability Expansion F124 TBMD (Theater Ballistic Missile Defence)" integrating the SM-3 was found to be feasible but the cost may approach the $1 billion. The SM-3 surface-to-air missiles may intercept targets outside the earth's atmosphere, for example, tactical ballistic missiles or low-flying satellites. Germany may purchase the new ESSM Block II in the near future. Although Block I remains highly effective in countering today’s threats, the upgraded version of ESSM known as Block II will build on Block I’s impressive capabilities. It will leverage existing technology and features a dual-mode X-band seeker, increased maneuverability, and other enhancements that will collectively enable it to defeat future threats to navies operating in hostile environments. Unlike RIM-7 and ESSM Block I, Block II’s active seeker will support terminal engagement without the launch ship’s target illumination radars.

Frigate Sachsen launching SM-2 SAM. Photo: Bundeswehr/Plankenhorn
Frigate Sachsen launching SM-2 SAM. Photo: Bundeswehr/Plankenhorn

The forward RAM of Sachsen.
The aft RAM of Sachsen.
For specialized anti-aircraft and antimissile defense (CIWS) other than the guns and the ESSM, the vessels have two Mk 49 Guided Missile Launching System (GMLS) with 21 missiles each ready to launch RIM-116 Rolling Airframe Missile (RAM) (Block 1A). Together, missiles and launching system comprise the RAM Mk 31 Guided Missile Weapon System (GMWS). RAM is in a class-leading weapon system providing a full perimeter protection to the vessel operator. The Block 1A missile has infrared guidance system that enables it to intercept missiles that are not emitting any radar signals while the Block 0 passive radar homing capabilities have been retained. The range exceeds the 9 km and the speed surpasses the 2 Mach.

B515 torpedo launcher of Hessen.
Eigenes Werk
B515 torpedo launcher of Sachsen.
For anti-submarine warfare (ASW) operations the vessels have two triple Eurotorp B515 324mm (similar to Mk32) torpedo launchers for MU90/Impact torpedoes. MU90 is a lightweight torpedo with a warhead of 32.7kg, a speed from 29 to a maximum of 50 knots (!) for about 25km and 12 km respectively (maximum speed). The maximum depth is 1,000m. This torpedo, is of fire-and-forget type and it has been designed to counter any type of nuclear or conventional submarine, acoustically coated, deep and fast-evasive, deploying active or passive anti-torpedo effectors while it has an extreme agility and maneuverability. In the main counter-counter measures are included stationary target detection capability, decoy classification and anti-jammer tactics.

Hard-kill and soft-kill weapon systems of a Sachsen class frigate. High resolution image here.
SRBOC launchers of Sachsen.
Photo: jens.lilienthal
SRBOC launchers of Sachsen.
Photo: arnekiel
The decoy launchers are the BAE Systems Mk 36 Super Rapid Bloom Offboard Countermeasures (SRBOC) Chaff and Decoy Launching System. It is a shipboard, deck-mounted, 6-barreled 130mm mortar-type array that launches type-specific countermeasures against a variety of threats. Following launch and dispersion, Mk36 SRBOC chaff and infrared countermeasures are designed to lure hostile missiles away from ships under attack by creating false target sets. The Mk36 SRBOC launching system is controlled from the ship’s combat management system and it is dependent on information provided by the ship’s detection and threat analysis equipment. The Mk36 SRBOC consists of the Mk137 launcher, firing stations at the bridge and CIC, the Mk160 power supply, Mk5 Mod2 or Mod4 Ready Service Lockers (RSLs), and a selection of munitions. Each vessel of the class is equipped with four Mk137 launchers. There is an intention to replace the systems with four Rheinmetall MASS systems.

Elements of Hessen's flight deck. Photo: MichaelStarkey, US Navy.
Modification: D-Mitch. Initial work: Hic et nunc

Lynx carrying two Sea Skua ASM
A Lynx inside Hessen's hangar.
Photo: Emmanuel L.
Each ship of the class carry two Sea Lynx Mk.88A or two NH90 (they are not yet operational) medium helicopters which can be accommodated in the hangar. The helicopters can be equipped with MU90 torpedoes, air-to-surface missiles Sea Skua (25km operational range), and/or heavy machine guns. The flight deck is rated to accommodate a 15 t helicopter in conditions up to sea state 6. However a helicopter of such size cannot be accommodated in the hangar. The helicopter handling system uses laser guided and computer controlled manipulator arms to secure the helicopter after landing.

Flight deck of frigate Sachsen. Photo: arnekiel
Sea King aboard a Sachsen class frigate
SMART-L radar
SMART-L of frigate Hessen
Thales SMART-L (Signaal Multibeam Acquisition Radar for Tracking, L band) is a naval 3-D long-range air surveillance radar operating in the D-band (or L-Band) from Thales Nederland, formerly Hollandse Signaalapparaten (Signaal). The passive electronically scanned array antenna has 24 elements; all are used for reception, while 16 are used for creating virtual receiver beams through digital beam forming. The beams' vertical elevation, and compensation for ship movement, is done electronically. Horizontal training is done by mechanically rotating the entire array. The system performs long-range detection of conventional air targets and medium range detection of small "stealth" type air targets such as the newest generation of missiles and supports target identification by interfacing with an IFF system. The system can track and maintain up to 1,000 air-targets and 100 seaborne targets. The maximum range of detection is more than 400km up to 70°elevation for patrolling aircrafts. Full Doppler processing for instantaneous radial velocity measurement and clutter suppression, combined with refined signal processing, guarantees excellent performance, especially against stealth targets in a littoral environment (range up to 65km). Clutter map and jamming map allow the detection and tracking of tangential flying targets and jammers. Surface surveillance is performed by a D-Band surface surveillance channel capable of automatic detection and tracking of up to 100 surface targets. The radar can detect an RHIB at 2km and a fast patrol boat at 7km. The system has an excellent ECCM performance.

The double hangar of a Sachsen class frigate

APAR and jammer of FL1800S on
the right of frigate Hamburg
APAR and FL1800S of Sachsen. The jammers
are the squared-off boxes. Photo: arnekiel
Thales APAR is the world's first Active Phased Array Multifunction Radar operating in the I-band (X-band) for naval Area Defence. The system provides a hemispheric coverage out to 150 km. It is capable of searching, tracking and supporting many ESSM and SM-2 engagements simultaneously. The use of the ICWI (Interrupted Continuous Wave Illumination) guidance mode that allows the guidance of 32 semi-active radar homing missiles in flight simultaneously including 16 in the terminal guidance phase. Any type of AAW engagement, including super-sonic high-divers, super-sonic sea skimmers and stealth targets is supported. It automatically and simultaneously performs search, track and weapon control tasks. APAR's horizon search offers an outstanding capability against asymmetric tactics. APAR's search function is optimized to detect very small targets at the horizon, also in a littoral environment. By realizing a short time between initial detection and fire control quality track, APAR creates maximum battle space against sea-skimming missiles, saturation and swarming attacks. APAR has unique target indication capabilities for multiple remote controlled small arms. ICWI is a guidance principle based on semi active homing (X band mid-course guidance). With semi active homing, the target is tracked and illuminated by radars on the ship. The missile tracks the target with its purely passive radar and homes in on the reflected energy. As only the target is illuminated, the missile has less trouble sorting out the target from its surroundings, compared to an active missile. The great advantage of this principle is that large amounts of illumination power can be brought to bear on the target to prevent jamming and misleading. The radar has a range of 150 kilometers and can track 250 air and 150 sea targets simultaneously.

Frigate Hessen. Photo: Hessen Kilho Park, US Navy

Rheinmetall MSP 500 EO-sensor
MSP atop the APAR
The Rheinmetall Multi Sensor Platform MSP 500 is a lightweight sensor system which is stabilized with high precision and is used by day and by night for the detection, observation and identification of objects and for target tracking and fire control. In combination with a radar system, the MSP 500 determines the altitude and range of an incoming target even at great distances. This system is also capable of recognize multiple targets which a radar only shows as a single target. The MSP 500 consists of a stabilized sensor package with a thermal camera and daylight camera, a 6 Hz laser rangefinder (range up to 40km), a video tracker as well as a vertical sensor and north sensor. Specifically designed for day- and night-time operation, it can also be used in adverse weather conditions.

SAM Electronics 9600M navigation radar atop the bridge. Photo: arnekiel

Two SAM Electronics (previously known as STN Atlas Marine Electronics) 9600M navigation radars complete the electronic sensors of the class. The targets are acquired manually and then tracked automatically (up to 40 targets). The aft radar act an approach control radar for the helicopters. Each vessel also is equipped with two Target Designation Sights (TDS) that provide means for optical investigation, target designation and weapon firing. The TDS is equipped with binoculars and the latest version includes a Laser Range Finder. Bearing and elevation data are fed into the CMS system but the TDS can also be used for emergency control of a gun or CIWS system. The importance of the function of the TDS is re-emphasized against asymmetric tactics such as piracy and insurgency.

Atop the APAR are the passive arrays of the FL1800S EW system. At the masthead
is the transceiver with a conical top of the system. Between the transceiver and the
arrays is a Link 16 collar. Photo: arnekiel

Elements of FL1800S ESM system
The electronic warfare suite includes the FL 1800S-II electronic support measures and countermeasures system, developed by DaimlerChrysler Aerospace, now EADS Systems & Defence Electronics. The system consists of four ESM-boxes, each of which contains two combined antenna faces. The antenna areas cover a frequency range from 0.5 to 18 GHz, with ten spiral antennas are available for each band. The system can be determined by the seven computer racks below decks the elevation and azimuth angles to an emitter and accurate count out the multipath. To disrupt enemy radars are four additional antenna surfaces which perform electronic countermeasures by passive phased signal legs with eight traveling wave tubes in the frequency range from 7.5 to 18 GHz. Each signal lobe can disturb a single target or linked together a radar. The frigates of the class have a bow-mounted  sonar which is the SAM Electronics DSQS-24B ( DSQS-21B Mod.) The sonar is also known as ASO 95.

Frigate Hessen of the Sachsen class

Bridge of Sachsen. Photo: Emmanuel L.
The Combat Management System of the ships is the Thales TACTICOS. The combat room accommodates the Multifunctional Operator Consoles (MOC) Mk3. Split second decision making in the high tech naval combat environment depends on tight integration of sensors and weapon control systems. Top performance demands flexibility for rapid response to changing conditions. This is the basis on which Thales Naval Nederland has developed the state-of-the-art combat management system TACTICOS. TACTICOS tightly integrates all subsystems for synchronised performance of the combat system and ship. It is designed to fully support a combat team in every stage of a naval operation, from pre-mission planning right up to post-mission analysis. This includes assessing and monitoring the tactical situation, planning and co-ordinating actions, and controlling actions and weapons. Even more information about TACTICOS you can read here. The ships of the class are fitted with the AAW cluster of TACTICOS. TACTICOS AAW cluster is the collection of infrastructure and software modules to execute the AAW function of the combination of SMART-L, APAR, SIRIUS (optional), Mk 41 launcher for ESSM and SM-2 and CIWS (optional).

A ship of F124 (Sachsen) class next to a ship of F122 (Bremen) class
A ship of F124 (Sachsen) class next to a ship of F123 (Brandenburg) class.
Photo: John Wilson
The communication equipment includes tactical data Link 11 and Link 22, VLF, HF, V/UHF, SATCOM, FOCON (Fibre Optical Communication Network) 128, FIT 10 Voice Terminal, INMARSAT, UMUS Integrated Message handling and control system and others.

A very nice photo of frigate Hessen


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