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The following is reprinted with permission from NAVINT, which is published twice monthly by Tileprint, Ltd. of 13 Condace Road, London, SW6 4BB.

From the 1st June 2002 issue

New Royal Navy SSNs’ Sonar Selected

Thales Underwater Systems UK (TUS) has received a contract from BAE Systems’ Astute class Ltd. to supply Sonar 2076 for the UK Royal Navy’s (RN) first three Astute class nuclear attack submarines (SSNs), ASTUTE, AMBUSH, and ARTFUL. In addition four 2076 ship-sets are already on order for a capability upgrade of four Trafalgar class SSNs.

The decision to use a proven sonar suite for the Astute class makes sense as it avoids the risk of a totally new system, and reduces the procurement and through-life cost of the £2 billion programmer.

(These figures may change as the design evolves)

Displacement: 7200 t (presumed to be surfaced)
Dimensions: 97m (oa)xl0.7mx10m (surface draught)
Propulsion: 1 Rolls-Royce PWR 2 nuclear reactor; c27 ,OOOhp; 2 Alstom geared steam turbines; 2 Alstom turbo-generators; 2 Alstom emergency diesel-electric units; pumpjet propulsor; 1 retractable auxiliary propeller
Speed: C30kn (submerged)
Armament: 6 53mm launch-tubes; mix of 38 weapons, including Spearfish torpedoes, TLAM Toma-hawk cruise missiles, or mines (in lieu of torpedoes)
Complement: 98

Originally ordered from Ferranti-Thomson (now TUS), 2076 is the RN’s first integrated sonar suite combining large flank arrays with three passive ranging spots on either flank with bow, towed, obstacle-avoidance and intercept arrays. A three year competition between Ferranti-Thomson and GEC-Marconi ended with a contract for five to seven years of full development and production. The prototype for shore trials and integration was delivered late in 1995.

Details of the system are sparse. Sonar 2079 may be the bow element. The system uses INMOS T9000 transputers, as in the AWS-950 FLASH dipping sonar. Its interfaces with the RN’s standard SMCS command system have been updated with Phase 6 and Phase 7 software to support functionality. Other elements of the upgrade included a new fibre-optic Tactical Weapon System Data Highway and the Telumia Submarine Acoustic Warfare System (SAWS), a knowledge-based tactical aid to provide course-recommendations and manage the deployment of decoys.

Although originally intended only for the Trafalgar class, 2076 has since been retrofitted to the five surviving Swiftsure class.

From the 1st July 2002 issue

News in Brief

Three of the Hellenic Navy’s Type 209 submarines are to have an air-independent propulsion (AIP) system installed by Hellenic Shipyards (Skaramanga). Like the Type 214 submarines currently under construction, these will use fuel cells with polymer electrolyte membrane (PEM) modules installed in new mid-sections that will be inserted into the existing hulls.

From the 15th August issue

The Royal Swedish Navy’s Heavyweight Torpedoes

The Royal Swedish Navy is in the process of re-equipping its submarines and surface ships with a new generation of 533mm (21 inch) heavyweight torpedoes. Since 1960, when Sweden acquired not only the results of the enquiry into the loss of HMS SIDON but the entire design and development background of the UK Royal Navy’s Mkl2 Fancy thermal-fueled torpedo, Swedish heavy-weights have been driven by high-test peroxide (HTP), with no accidents. The then state owned company FFV was given the task of producing the first of a series designated Tp 61, and variants were numbered:

  • Tp 611, a wire-guided anti-ship and anti submarine weapon
  • Tp 612, a swimout variant of Tp 611
  • Tp 613, the standard Royal Swedish Navy variant with wire-guidance, a two-way data-link and dual speed
  • Tp 617, the export variant of Tp 613, sold to Denmark, Norway, and Yugoslavia.

Other variants, Tp 614, Tp 615, and Tp 616, may have been experimental models not put into production. Tp 613 is to be replaced by Tp 62, and Tp 617 is to be upgraded.

Development of a new generation heavyweight, designated, Tp 62, began in the mid 1980s by the Navy’s defence procurement agency, the Forsmaterielvarets (FMV), and the successor to FFV, Bofors Underwater Systems (now Saab Bofors Underwsater Systems). A contract worth an estimated SKR200 million was awarded by FMV in April 1991, to complete development. It was hoped to get the weapon into service around 1995, and sea trials began at Motala in 1992, but the SKR568m production contract was not signed until 17 December 1997. Deliveries started in the summer of last year, about 18 months later than planned. A tropicalized export variant, T96, was redesignated Tp 2000. The Swedish order was to be 600 torpedoes, while 300 were to be made for Denmark and Norway.

The major advance over Tp 613 is the adoption of an axial swashplate twin sinusoidal cam piston engine with seven cylinders. A shrouded pumpjet similar to that in the British Spearfish is made by BAE Systems’ Underwater Weapons Division. The new engine maintains the 60kn capability of the Tp 61 series, with extended range. Precise figures are classified, but relaiable sources quote a range of more than 21.5mm (40km) at 40kn, falling to about 33mm at top speed. Exhaust gases are vented outboard and dissolve in seawater, so Tp 2000 leaves no wake.

Tp 2000 is 30 percent lighter and smaller than its predecessor, and has a comparatively light 240kg warhead, presumably using a shaped charge to enhance lethality. It is actuated by impact and proximity fuzes, using active, passive or combined active/passive homing to track several targets simultaneously. If the two-way wire link is severed or damaged, the torpedo’s on-board micro-processor takes over full command, calculates the target’s anticipated position and guides itself to the predicted point of impact. This involves the initiation of one of several pre-programmed search patterns. In the standard configuration 80 different types of data can be transmitted in both directions, and a fibre-optic link allows the transmission of even more data.


Length: 5.99m
Diameter: 533mm
Weight: 1450kg
Warhead: 240kg
Speed: 60kn
Range: 40km+
Running depth: 500m+

The Tp 61 series played an important part in convincing the RN to return to thermal fuel for its Spearfish programmer. The high speed at maximum depth required for the Cold War could not be achieved by traditional steam torpedo engines or batteries, so the misgivings had to be overcome. The design team at Motala have a simple explanation for the safety record of HTP in the Tp 61 series and its successors. When the British Mk12 Fancy was examined in detail the Swedish engineers criticized the decision to adapt a standard Brotherhood engine, then driving the successful Nk 8, by simply converting the fuel supply to HTP. This brought the sensitive fuel into contact with incompatible materials, and created a high risk of a fuel fire. The Tp 61 team redesigned the fuel supply completely, avoiding the use of any material likely to raise the temperature of the fuel. This factor, combined with a thorough wash-through after each run, has given the Royal Swedish Navy safety and reliability as well as outstanding performance.

Typhoon SSBN Returns to Service

A Project 941 Typhoon class nuclear powered strategic missile submarine (SSBN) has returned to service after a 10 year conver-sion to a missile trials boat. The former TK-208 has been renamed DIMITRI DONSKOI, a traditional Russian name, and was relaunched at the Sevmashpredprivatiye shipyard at Severodvinsk on 26 June.

TK-208 was one of six Project 941 SSBNs designed by the Rubin Bureau, and at 26,500t submerged displacement they were the largest submarines in the world. They joined the Northern Fleet between December 1981 (TK-208) and 1989. The triple hulled design (two cylindrical pressure hulls surmounted by a smaller cylinder) was intended to lie on the bottom in time of crisis, awaiting instructions to launch their 24 RSM 52 (SS-N-20 Sturgeon) ballistic missiles. To boost morale during the long wait on the seabed they were given such luxuries as a sauna.

It had been hoped to re-arm the class with the new RSM 52V (SS-N-28 Bark) missile, and TK-208 returned to her builders at Severodvinsk in 1992 to stan the modernization programme. The RSM 52V missile failed in early test-firings, however, and development was terminated in 1998. The missile system was also intended for the new project 955 Borey class, of which YURI DOLGORUK.I is the lead boat. The decision was made to re-orient the modernization of TK-208 to allow her to be the trials boat for the submarine-launched version of the land-based TOPOL-M (SSN-27 Bulava). She was subsequently given the name DIMITRI DONSKOI, reflecting the Russian Navy’s wish to revive famous traditional names.

Admiral Gennady Suchkov, commanding the Northern Fleet, has confirmed that only two Project 941 SSBNs remain in service, TK-17 and SEVERTSTAL (TK-20). They have recently under-gone maintenance refits at the Sevmashpredprivatiye yard. TK-202 has been defueled at the Zvezdochka facility in Severodvinsk under the Cooperative Threat Reduction Programme, and TK-12 and TK-13 are laid up awaiting scrapping.

News in Brief

  • The Russian built Project 877EKM submarine INS SINDHU-GOSH is to be modified to launch 3M-54E Klub-S anti-ship cruise missiles. She is the fifth Indian Kilo type diesel-electric submarine to be modified: SINDHUVIR, SINDHURA TNA, SINDHURAJ and SINDHUKESARI have already received the upgrade at Severodvinsk and the New Admiralty yard in St. Petersburg. SINDHUGOSH is to start her refit this month and will be recommissioned in 2004. The 3M-14E land-attack variant may be acquired later.

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