The world’s first stealth warships: corvettes project Visby (Sweden)

The world's first stealth warships: corvettes project Visby (Sweden)
In recent decades one of the most fascinating destinations in the development of military technology are called stealth technology. A set of measures aimed at reducing visibility to radar technology allows tangibly improve the combat effectiveness of the aircraft or ship. With all of this in the case of the use of stealth aircraft technology often leads to the «wrong» aerodynamic face of the aircraft. Warships, in turn, is not so demanding architecture topside. Because in recent years a huge number of projects warships, which in one way or another used measures to reduce visibility to radar.
While some countries are using only some technical solutions or preparing to build these stealth ships, Sweden already uses several corvettes designed taking into account the largest decrease visibility. Corvettes project Visby («Visby») are scarce — only 5 built such ships. Yet, they are combined in a number of unique measures to solve a number of combat missions with the least risk to be found.
Drafting Visby preceded experiments started to explore stealth technologies and their prospects in military shipbuilding. In the late 80s the Swedish industry has built a hovercraft skeg type Smyge. Small ship (full displacement of about 140 tons) will determine the future of several new technologies, as some elements of the form work promising warships. A huge number of developments, acquired in-process project Smyge, was used in the upcoming draft Visby.

In the early 90-ies the military department of Sweden going to do two projects at once ships: YSS (Ytstridsfartyg Storre — «Large warship») and YSM (Ytstridsfartyg Mindre — «Small warship»). But soon after the launch of the project put together in order to save. Further work was conducted by Kockums project YS2000 (Ytstridsfartyg 2000 «Battleship 2000s»). Later, the project received a new title, a corresponding name of the lead ship — Visby. Due to the merger of 2-projects YS2000 ships had to make a wide range of tasks, from submarine search and attack surface targets before placing minefields and patrols.
The project was completed YS2000/Visby the middle 90s. It was used a number of technologies, new not only for the buffet, and for the world shipbuilding. In February 1996, the lead ship accomplished tab, get the name of Visby. The ship was launched in 2000 and until 2005 was on trial. From 1997 to 1999 were laid 5 new corvettes, but the construction of the last of them (Uddevalla) soon canceled. In 2009, in the Swedish Navy had taken the second and third ships of the project and Helsingborg Harnosand. Another two new corvette, Nykoping and Karlstad hitherto pass the tests.

Kockums employees managed to make the first in the world warship fully uses stealth technology. Corvette came comparable small: the total length of 72 meters, maximum width — 10.4 m, draft — about 2.4 m Through the use of new technologies Swedish shipbuilders were able to reduce the weight of the structure. Total displacement of the lead ship Visby does not exceed 640 tons.

The main factor that will reduce the weight of the structure, was a unique composite material from which made a number of fundamental structural parts. The basic material for the production of the hull and superstructure chosen set of polymers reinforced with carbon fiber and vinyl. In the course of a long research Swedish spice unable to find a suitable for the introduction of composite, providing light weight design (two times lighter than a similar structure made of metal), the highest hardness and impact resistance. With all this one of the main reasons for the introduction of a composite material became its low reflectivity. Frame of the ship collected iron parts.

The world's first stealth warships: corvettes project Visby (Sweden)


The hull and superstructure Visby corvette made in monoblock form: surfaced part of the body goes into the superstructure smoothly without unnecessary parts that can increase the visibility of the ship. Water part of the ship is a combination of conjugated flat panels of various shapes. Underwater contours made «traditional», since they do not affect the visibility to radar systems. On the forecastle of the ship provided cover for covering artillery installation of radar radiation. In the middle part of the housing is a correspondingly shaped superstructure. On the roof of the superstructure has an antenna mast, radio waves cover closed. Aft enclosure reserved for the landing field length of about 20 meters. All weapons systems are also mooring equipment located inside the hull or superstructure and locked shields made of the number of the same materials as the body.

Internal volume of the housing project Visby ships watertight bulkheads broken into eight compartments. In 3 of the nasal compartments are cabins and crew Kubrick, sanitary facilities, and nasal diesel generator, sonar and thruster. On the various decks in the fourth compartment are mess-room and dining room, galley with pantry, as the main command post. Noteworthy that space wardroom is also used as a hospital. In the fifth volume of the compartment placed various weapons systems and accessories. In addition, in the fifth compartment is helm main power plant and aviation fuel tank. In the hold of the sixth through eighth compartments are various main power plant equipment. Upper deck reserved for the torpedo tubes and volume to the desired weapons. As required in the aft part of the ship can be equipped with a helicopter hangar.

The main power plant project Visby corvettes made by CODOG system and uses several types of engines. In the sixth compartment is equipped with two diesel engine MTU 16V 2000 N90 capacity of about 1,770 hp each. Noise Reduction sliders mounted on shock absorbing devices. Diesel engines are used when driving at economical speed of about 15 knots. To accelerate to maximum speed ship can use four gas turbine engine Vericor TF50A total capacity of 16,000 kW (21,750 hp about) installed in the stern compartments. When using the highest power engines Visby corvette can accelerate to 35 knots. Cruising range — up to 2,500 miles.
Torque engines through gears is transmitted to the two water jet propulsion KaMeWa 125 SII. At speeds of 15 knots water jet provides about twice the lowest noise level in comparison with classic propellers. Water jet allows to reduce the acoustic visibility ship. In addition, the measures used, reducing the visibility of the corvette in the infrared spectrum. Exhaust gases are all 6 engines found through the pipe in the stern of the ship, located very close to the water.

Maneuverability of the ship provided rotary nozzles water cannons, also with 2 rudders mounted behind them. Last allow you to maneuver with greater efficiency at low speeds. In addition, in the bow of the Visby class corvettes foreseen thruster HRP 200-65.

All 5 Visby corvettes project initially had a common set of avionics. As the primary means used to detect targets three-coordinate radar Ericsson Sea Giraffe AMB. Properties that allow you to create search radar targets and operate in targeting. Station can find small air targets such as anti-ship missiles at distances up to 70-80 km. To counter the enemy’s electronic systems are equipped with multi-band complex ships EW.

Combat Information Control System (CICS) CETRIS C3 is based on 2-major subsystems: the complex weapons control Saab Systems 9LV mk3E and information support system MAST. All components of management information system built on the basis of modern digital devices. For the convenience of transmitting orders and instructions to the ship type Visby for the first time in world practice used special electrical system. Though what a crew member using a special terminal, can get in the electric form of all documents to which it has access. Similarly, a system of communication with other ships and command.

New Swedish corvettes can without the help of others search of enemy submarines. To this end they are equipped sonar system CDC Hydra. The complex consists of passive towed sonar, also lowered and placed in the body of the active station type. In addition, the ship carries several remotely operated vehicles that can be used to search for submarines. Sonar system collects data from all stations and transmits the data to the system found on gun control. Of particular interest is the station installed in the bow of the hull ships. Having comparable narrow beam, it can be used to search for sea mines.

When developing complex weapons Visby class corvettes creators of the project provided the ability to «specialization» of another ship or to perform certain tasks. With all of this all the ships are a few common weapons systems. Before superstructure on corvettes set gun Bofors 57 mm Mk3 with automatic weapon caliber 57 mm. This gun is able to keep pace with the fire up to 220 rounds per minute and hit targets at a distance of 10-11 km. High-explosive shells for guns equipped with remote-controlled detonator, allowing to create explosion of ammunition at the right moment and «cover» the purpose shrapnel. This, namely, offset by comparable small caliber guns. In the stowed position is under the gun shield casing of composite materials.

Design features Visby ships have allowed them to equip different weapons, in accordance with the wishes of the naval forces of Sweden. So, the first four ships (from Visby to Nykoping) intended to search for submarines and sea mines, must also accompany the convoys. In this regard, corvettes are universal torpedo. These weapons are located in the aft part of the ship and stowed flap closure, not projecting beyond the boundaries of the enclosure. In the fore part of the body, near the artillery installation, there are eight rocket mortars Alecto, who can use anti-submarine and anti-torpedo ammunition. Complex control system Alecto, working with CICS ship can immediately reflect the torpedo attacks with 2-directions.

Fifth ship of Visby (Karlstad) has a different set of weapons. Assumes that the corvette will detect and storm enemy ships, what shall adequately manage Missiles. Instead torpedo in the aft part of the ship there are anti-ship missiles launchers Saab Bofors Dynamics RBS 15 Mk2. The use of such tools will allow the corvette Karlstad storm enemy ships at a distance of 200 km. In addition, close to the anti-ship missile launchers plan to install air defense missile system Saab Bofors Dynamics RBS 23 BAMSE ammunition vertical launch. Implementing this will allow SAM to protect the ship from enemy aircraft and missiles within 15 kilometers. There is information about rooms in the aft part of the corvette automatic cannon 30 mm.

The world's first stealth warships: corvettes project Visby (Sweden)


Visby corvettes in ASW variant can carry one helicopter Augusta A109 with suitable avionics equipment. As required, the helicopter can land on at least some of the ships of the series, but the hangar there is only three of them: Helsingborg, Harnosand and Nykoping. Not counting the helicopter ships are in store fuel and ammunition necessary to destroy enemy submarines.

According to reports, the complex electronic means Visby corvettes project is designed Makarov, so the crew could search and storm the goal, not including any radiators. As needed ships can receive external target designation. With all of this it should be noted that the decrease in radar, infrared and acoustic signature excellent effect on the actual properties of the latest Swedish corvettes. In some sources mentioned that modern radars can find calm in Visby ship at a distance of less than 20-22 km. In rough detection distance is reduced to 11-13 km. So makarom using passive means of detection, corvette can get a huge advantage over the enemy. In addition, the claims made by electronic systems and weapons suggest that the introduction of radar or active sonar does not reduce the combat potential of the corvettes. Thus, the detection range of the radar Ericsson Sea Giraffe AMB and firing range missiles Saab Bofors Dynamics RBS 15 Mk2 about 200 km in theory allows the last of the Visby class corvettes to storm enemy ships before they will be able to find it.
In the spring of 2012, she graduated from the Saab repair and modernization project lead ship Visby, commissioned by the Swedish Ministry of Defence. In the process of upgrading the ship was about 60 different upgrades of equipment and weapons. Namely, underwent refinements detection systems and communications, anti-submarine weapons, and equipment designed for operation with helicopters. In 2014, a similar means to finish upgrading other antisubmarine corvettes.

Despite its moderate size and a small amount, type Visby corvettes are among the most fascinating and sverhtehnologichny ships in the world. In addition, in the course of this project, the Swedish shipbuilders for the first time in the world could do and build a series of warships to the widespread introduction of stealth technology. Stated especially corvettes look curious and entice attention. But fighting abilities 5 ships cause some issues. Over the past few years are in the ranks of the project Visby corvettes participated solely in the exercise and never failed to show their potential in the criteria for actual operations. Yet, in this case, they are the world’s first stealth warships,.

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