Visby-class corvette

The Visby class is the latest class of corvette to be adopted by the Swedish Navy after the Göteborg and Stockholm-class corvettes. The ship's design heavily emphasizes low visibility, radar cross-section and infrared signature. The first ship in the class is named after Visby, the main city on the island of Gotland. The class has received widespread international attention because of its capabilities as a stealth ship.

For other ships with the same name, see Visby-class destroyer.
HSwMS Helsingborg (K32)
Class overview
Name: Visby class
Builders: Kockums
Operators:  Swedish Navy
Preceded by: Göteborg class
Cost: $184 Million[1]
In commission: 16 December 2009
Planned: 6
Completed: 5
Cancelled: 1
Active:
  • HSwMS Visby
  • HSwMS Helsingborg
  • HSwMS Härnösand
  • HSwMS Nyköping
  • HSwMS Karlstad
General characteristics
Type: Stealth Missile Corvette
Displacement: 640 tonnes
Length: 72.7 m (239 ft)
Beam: 10.4 m (34 ft)
Draught: 2.4 m (7.9 ft)
Propulsion:
Speed: 35 knots (65 km/h)+
Range: 2,500 nmi (4,600 km) at 15 kn (28 km/h)
Complement: 43
Sensors and
processing systems:
Electronic warfare
& decoys:		 Rheinmetall TKWA/MASS (Multi Ammunition Softkill System)
Armament:
Aviation facilities: Helicopter pad

The ships are designed by Swedish Defence Materiel Administration (FMV) and built by Kockums AB.[3] The first ship of the class was launched in 2000 and since then the construction was fraught with repeated delays. Finally in December 2009, the first two ships of the class were delivered to the Swedish Navy by the FMV, albeit with greatly reduced operational capability.

Design

The hull is constructed with a sandwich design consisting of a PVC core with a carbon fibre and vinyl laminate[4] (see also the Oceanic-Creations spin-off). There are multiple advantages to using composite materials in ship hulls. Good conductivity and surface flatness means a low radar signature, while good heat insulation lowers the infrared signature and increases survivability in case of fire. The composite sandwich used is also non-magnetic, which lowers the magnetic signature. Composites are also very strong for their relative weight, and less weight means a higher top speed and better maneuverability. The composite weighs roughly 50% less than the equivalent strength steel.[5]

Visby's angular tumblehome design reduces its radar signature. Jan Nilsson, one of the designers, told BBC News Online: "We are able to reduce the radar cross section by 99%. That doesn't mean it's 99% invisible, it means that we have reduced its detection range."[1] The 57 mm cannon barrel can be folded into the turret to reduce its cross section. There are plans for additional improvements in this area, especially for the deck rails and masts.

History

Much of the design was based on the experiences learned from the experimental ship HSwMS Smyge. The class was originally designed to be divided into two subcategories where some ships were optimized for surface combat and others for submarine hunting; however, this was changed due to cutbacks.

A helicopter, such as the Agusta Westland A109M selected by Sweden, can land, take off, and refuel on the upper deck. A helicopter hangar was originally planned but was considered to be too cramped and was removed.

The ships took an exceptionally long time from launch to delivery and the construction has been fraught with repeated delays. In 2008, the only weapons system that had been integrated and tested in Visby was the gun.

Finally, on 16 December 2009, the first two of the corvettes were delivered to the Swedish Navy by the Försvarets materielverk (FMV).[6] The two ships, K32 and K33, were delivered with underwater and surface/air sensors fully integrated. However, the only weapon that had been integrated and test fired on the ships was still the Bofors 57 Mk3 gun. The FMV calls this version 4, which aims to get the ships into service and start training crews.

HSwMS Visby

Version 5 is due in 2012, and is intended to supplement the ships with mine clearance systems, helicopter landing capability (only K31 is certified to date), anti-surface ship missiles and additional stealth adaptation. Visby was the first of the corvettes to be upgraded to Version 5. On 22 March 2012 FMV reported that the ship had been modified and that the system would be tested before reentering the Swedish Navy by the end of 2012.[7]

Although the design of the ships originally called for the installation of surface-to-air missiles, on 18 September 2008 the Genomförandegruppen cancelled the project in order to rationalize the procurement of defence materiel for the Swedish defence.[8]

Units
Number Ship name Laid down Launched Commissioned Service Status Coat of arms
K31 Visby 17 February 1995 8 June 2000 16 September 2002 4th Naval Warfare Flotilla Active
K32 Helsingborg 27 June 2003 16 December 2009 4th Naval Warfare Flotilla Active
K33 Härnösand 16 December 2004 16 December 2009 3rd Naval Warfare Flotilla Active
K34 Nyköping 18 August 2005 16 September 2015 3rd Naval Warfare Flotilla Active
K35 Karlstad 24 August 2006 16 September 2015 3rd Naval Warfare Flotilla Active
K36 Uddevalla Cancelled

All systems for the ship Uddevalla were acquired, but the ship was later canceled, so there are now plans to build a full Visby class simulator.

PTK Visby is the designation of the formation doing system tests and readying the ships for active service within the Swedish Navy. The formation is under the 3rd Naval Warfare Flotilla but takes its orders from the FMV. The system tests are taking a long time partly because of funding issues and partly because of the novel and cutting-edge nature of the platform.

Similar ships
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References
  1. Summers, Chris (10 June 2004). "Stealth ships steam ahead". BBC News. Retrieved 4 April 2015.
  2. "TF Series Marine Gas Turbine Engines - 4000 to 5600 Hp" (PDF). Vericor. Archived from the original (pdf) on 2016-03-04. Retrieved 4 April 2015.
  3. Mack, Ben (2009-02-12). "Sweden Builds World's First Stealth Ships". Wired. Condé Nast Publications. Archived from the original on February 13, 2009. Retrieved 2009-02-12.
  4. "Visby Class Corvettes, Sweden". naval-technology.com. SPG Media Limited. Retrieved 4 April 2015.
  5. "Visby Class Corvette". Saab Group. 2014. Retrieved 4 April 2015.
  6. "Visby corvettes delivered to the Swedish Armed Forces". Swedish Defence Materiel Administration. 2009-12-21. Archived from the original on 2010-08-18. Retrieved 2010-02-02.
  7. Visby uppgraderas (in Swedish), SE: FMV, archived from the original on March 27, 2012
  8. Effektivisering av försvarsmaterielförsörjningen - omprövning av materielprojekt (in Swedish), SE: Regeringen, 18 September 2008, archived from the original on 9 April 2015, retrieved 4 April 2015.
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