Swedish Navy, Visby stealth-corvette [Archive]

glofs

09-01-2003, 05:02 AM

http://www.hkpflj.mil.se/save/images/local/hmsvisbyler025.jpg

The Visby is one of Swedens newest 'Stealth' boats. Construction of the 72 metre vessel was begun in 1996, was launched in June of 2000, began its sea-trials in December of 2001, and is expected to enter service January 2005. This radical and highly advanced craft is constructed of a sandwich composite material consisting of a PVC core and skins of carbon fibre and vinylester plastic which provide low weight,radar reflectivity, and magnetic signatures. The advanced FRP material provides low visibility from electrical and magnetic detection. The above surface configuration provides low optical and infra-red detection. The craft is not completely 'invisible', however by the time a defender becomes aware of its presence through conventional detection methods it would already be too late to take counter- measures. The vessel is meant for mine-countermeasures, anti-submarine warfare, attack and anti-surface roles. Powered by 4 TF 50 A gas turbines producing a total of 16,000 kW and driving two Waterjet Propulsors, the craft is capable of a maximum speed of about 35 knots.
http://foxxaero.homestead.com/indrad_023.html

http://www.hkpflj.mil.se/save/images/local/hmsvisby4_lumweb..jpg

The Visby Class corvette is the first vessel in the world to have fully developed stealth technology, combined with high operational versatility. The outstanding stealth properties fundamentally change the ship's survivability and improve its mission effectiveness.
http://www.kockums.se/SurfaceVessels/visby.html

More pics and info:
http://www.marinen.mil.se/visby
http://www.hkpflj.mil.se/save/article.php?id=5820
http://www.kockums.se/News/photostock/photosurface.html (hi-res)
http://www.wehrtechnik.net/wehrtechnik/fregatte_visby.html

hendrix33

09-01-2003, 09:38 AM

A piece of art...

Source: http://www.naval-technology.com/projects/visby/index.html

http://www.naval-technology.com/projects/visby/images/Visby_1.jpg
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http://www.naval-technology.com/projects/visby/images/visby4.jpg

VISBY CLASS CORVETTE, SWEDEN
The Visby Class of stealth corvettes is being built for the Swedish Navy by the Swedish company Kockums (a subsidiary of HDW of Germany). Construction began in 1996 at Kockums' Kalrskrona yard. The Visby (K31) was launched in June 2000 and was delivered to the FMV (the Swedish Defence Materiel Administration) in June 2002 to be fitted with weapons and combat systems. This will be followed by combat system trials and then operational trials with entry into service in January 2005. The second, HMS Helsingborg, was launched in June 2003. Five Visby class vessels are to be delivered to the Swedish Navy by 2007, which has an option on a sixth vessel.

The first four Visby corvettes for the Swedish Navy are for Mine Countermeasures (MCM) and Anti-Submarine Warfare (ASW). The last vessel will be primarily for the attack and anti-surface warfare role. A helicopter, such as the AgustaWestland A109M selected by Sweden, can land, take off, and refuel on the upper deck. Preparation has been made for the installation of a hangar on the ship.

Kockums has signed a partnership agreement with Northrop Grumman Ship Systems, under which Kockums will join Northrop Grumman's team for the US Navy's Focused Mission Vessel Study for the design of the Littoral Combat Ship (LCS) element of the DD(X) future family of surface combatants. Northrop Grumman plans to use the Visby as the baseline for its proposal for the LCS. Up to 60 LCS vessels could be built for the USN.

DESIGN

The design of the Visby has been directed to minimising the optical and infra-red signature, above water acoustic and hydroacoustic signature, underwater electrical potential and magnetic signature, pressure signature, radar cross section and actively emitted signals. A stealth corvette of the YS 2000 design has a detection range of 13km in rough seas and 22km in calm sea without jamming. In a jammed environment, the Visby would be detected at a range of 8km in rough sea and 11km in calm sea.

The hull material is a sandwich construction comprising a PVC core with a carbon fibre and vinyl laminate. The material provides high strength and rigidity, low weight, good shock resistance, low radar and magnetic signature.

COMMAND AND CONTROL

The vessel's CETRIS C3 (command, control and communications) system consists of the SaabTech Vectronics (formerly CelsiusTech) 9LV Mk3E combat management system, the MAST decision support aid and the integrated communications system. The 9LV Mk 3 is based on open system architecture and uses the Windows NT operating system. The SaabTech CEROS 200 radar and optronic fire control system has been ordered for the Visby and will be fully integrated into the combat management system.

The communications system has a high capacity digital communications switch, developed by Danish company Maersk Data Defence (formerly Infocom) together with Karlskrona, which interconnects the voice and data communications channels. The system provides internal communications or open conference lines and access to external communications with various radio links and land-based networks.

MISSILES

Visby vessels will not initially be fitted with an air defence missile system, but could later be equipped with one, such as the Saab Bofors Dynamics Rb23 BAMSEA or Raytheon Evolved Seasparrow Missile.

The corvettes will be equipped with eight Saab Bofors Dynamics RBS 15 anti-ship missiles. The missiles will be installed below deck and be fired through special hatches to maintain the vessel's stealth. The missile's exhaust plumes will be managed in separate canals.

ANTI-SUBMARINE WARFARE
The Visby is equipped with a suite of ASW 127mm rocket powered grenade launchers, depth charges and torpedoes. There are three fixed 400mm torpedo tubes for Tp 45 anti-submarine homing torpedoes.

Saab Dynamics are developing the ALECTO multi-mission launcher to equip the Visby Class. The launcher will be able to dispense ASW weapons, torpedo countermeasures and chaff and infrared decoy rounds.

GUN

The Visby is equipped with a Bofors 57mm 70 SAK Mark III general purpose gun. The gun has a fully automatic loading system containing 120 rounds of ready-to-fire ammunition. The gun fires up to 220 rounds/minute to a maximum range of 17,000m.

MINE COUNTERMEASURES (MCM)
The Visby will carry Saab Bofors Underwater system ROVs (Remotely Operated Vehicles) for mine hunting and the STN Atlas Elektronik Seafox ROV for mine disposal. The minehunting ROVs are a development of the Double Eagle Mk III.

The Visby corvettes will be fitted with the Hydra multi-sonar suite from Computing Devices Canada (CDC), which integrates data from a passive towed array sonar, dual frequency active variable depth sonar (VDS), hull-mounted sonar and the ROVs.

SENSORS

Ericsson's Sea Giraffe 3D C-band radar is fitted for air and surface search. There is also an I-band surface search and I/J band fire control radar.

The electronic support measures (ESM) system is the Condor Systems C-3701.

PROPULSION

The Visby is equipped with a combined diesel and gas (CODAG) turbine arrangement. Four TF 50 A gas turbines from Honeywell and two MTU 16V 2000 N90 diesel motors are connected to two gearboxes which run two Kamewa waterjet propulsors. The motors provide a maximum speed of 15 knots for long duration and 35 knots for short duration. The ship has rudders and bowthrusters for harbour manoeuvring.