| Stealth Ships Steam Ahead The Swedish Navy is testing out a new ship which is believed to be the most "invisible" yet. The Royal Navy and the US Navy both have plans of their own for similarly futuristic "stealth" ships. BBC News Online investigates the shape of the future of naval warfare. Ever since radar was first used by the British shortly before World War II, military boffins have been trying to think of ways to beat it. The US Air Force invented the first "stealth" aircraft, the F117, and the B-2 bomber, in the 1980sBoth planes were designed in such a way as to keep their radar "signatures" to an absolute minimum. Now naval architects have come up with a similar way of beating the radar. The first Visby corvette, designed by the Swedish shipbuilders Kockums and built at their Karlskrona yard, has just completed sea trials with the Royal Swedish Navy. It will come into service in January and will be followed by four more. American designers are working on the US Navy's own fleet of stealth ships, the DD(X) destroyer, which is due to enter service in 2011. Northrop Grumman Ship Systems is leading a consortium which has been given the $2.8bn contract to build the futuristic ships. Northrop Grumman spokesman Brian Cullin told BBC News Online: "The DD(X) will be as revolutionary as the Dreadnought was when the British introduced it at the turn of the last century." He said the DD(X) would save the US Navy a fortune in running costs because it would have 200 fewer sailors to operate it than the existing Arleigh Burke class. Mr Cullin said it would also be more efficient for the US Treasury. "In the Iraq war last year the Navy was firing Tomahawks at $1m a piece. Projectiles for the DD(X) will cost significantly less and it will be able to fire large volumes of surface fire at close range, which will bring huge economies." |
 WAYS OF SPOTTING SHIPS
 DDX-Destroyer |
 The Visby Length: 73m
Cost: £100m ($184m)
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Fooling Radar As for the Royal Navy, it too will have a new breed of stealth ships in action soon. HMS Daring, the first of the Type 45 destroyers, is being constructed at BAE Systems' Govan and Scotstoun yards in Glasgow. It is to due to enter service in 2007. But the Swedes are in the lead, with the Visby. It is constructed almost entirely of carbon fibre, the same material used to make the chassis of Formula One cars and the hulls of racing yachts. Its angular design gives it a minimal radar signature, known as a cross-section, and its 57mm cannon can also be retracted to reduce it still further. John 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." In a nutshell, if the Visby was 100km from an enemy vessel it could see the enemy on its radar but not vice versa. It could get within 30km of the enemy before being spotted. Carbon fibre is also a lot lighter than steel and the Visby, at 600 tonnes, is half the weight of a conventional corvette. Mr Nilsson said: "Naval officers fall in love with [this] ship. It's not classically beautiful. In fact it looks like a lunchbox. But it has better manoeuvrability and can achieve that level of stealth." |
| Avoiding Angles A Ministry of Defence spokesman said naval designers have known for a long time that radar signatures depend on the angles involved. He said: "The trick is to avoid right angles, which reflect radar right back. "The whole idea is to make it look like it's not a big ship." A BAE Systems spokesman said the design of the Type 45 and the materials used would reduce its radar visibility but he said the hull would be steel, not carbon fibre. He said: "It will provide the future backbone of the Royal Navy as it faces multiple threats." |
 Type 45 Destroyer Length: 152m |
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State of the Art The MoD spokesman questioned the "survivability" of ships made of carbon fibre, and also doubted whether they could be able cope with ocean conditions. Mr Nilsson said the Visby - which is 73m long - was only designed for littoral, or coastal warfare, but he said they had designed a 120m ship which had worked well technically. As for the question of survivability, he said: "It is not so much a question of material but physical size. Any ship below 100 metres, regardless of material, will be gone if it's hit with a modern surface-to-surface missile." The new ship is also controlled by state-of-the-art computers using a Windows NT operating system. But Kockums and the Swedish Navy deny it could be sabotaged by hackers and say that even if it did they could fall back to traditional steering and navigation. Mr Nilsson said: "I am not an expert in computer security but we have focused a lot on that and this ship has a lot of firewalls and clever ways of avoiding it (being hacked)." Commodore Stephen Saunders, editor of Jane's Fighting Ships, said: "Stealth is not an end in itself. The value of a ship is in what it can deliver. "Undeniably having a stealth ship allows you to operate in places where you might not have been able to operate." He said one potential flashpoint where they may be useful was around Taiwan, in the event of a clash between the US and Chinese navies. But Commodore Saunders said: "Ships will never be completely invisible. "A lot of modern submarines are extremely hard to detect, but that is always going to be difficult for a surface ship to match". |
| SUBMARINE STEALTH Stealth technology includes everything that minimises signatures and signals, with the aim of increasing the efficiency of the ship's own countermeasures and sensors, and of preventing or delaying detection and identification. Signature control, or stealth, is nothing new to armies and navies. The legendary Trojan Horse is a good example of cover and concealment from the past. Among submariners stealth is second nature and something of fundamental importance to survival. Now, the combination of tactical developments and advances in technology has reached the point where stealth also presents itself as a very attractive option for surface vessels. Action without being seen - submarine tactics in a nutshell. A submarine disappears from sight when it dives, but it can still leave a trail of sound, heat, sonar reflections and magnetic anomalies. For the submarine to remain concealed, all of these signatures must be minimised. Some examples of the most important elements of submarine stealth: All emitted sound that can be detected by hydrophones must be suppressed. Engines and other sound-emitting equipment must be carried in sound-attenuating mountings. Flow noise, generated by the flow of liquids in pumps and pipes, must be minimised. The Silent Stirling AIP system The AIP system comprises the virtually vibration-free and silent Stirling engine. The fact that the submarine can operate at great depths for long periods of time is also an important stealth factor. |
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Moving Silently The hydrodynamic design of the hull, rudder and
propeller is of vital importance. The flow noise when the submarine
travels through the water can disturb the submarine's own hydrophones
and can also be heard by the enemy. Active sonar is a serious threat. The main factors in avoiding detection are the geometry of the hull, fin and control surfaces, and the materials used. Counteracting magnetic fieldA vessel travelling on the surface or under water gives rise to detectable local disturbances in the Earth's magnetic field. This can be avoided by demagnetising the vessel by generating a counteracting magnetic field. |
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ELF Signature-
a hydrodynamic phenomenon The head of a submarine mast must have the smallest possible geometrical size. The use of fairings designed to minimise the reflection of radar waves and radar absorbing material attached to the mast surfaces ensures a low signature level. Manoeuvrability - a method for staying concealed The concept of stealth also includes manoeuvrability. The fact that a submarine can travel and turn quickly, efficiently and quietly enables it to evade the enemy in certain circumstances. |
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As Quiet as a Fish
The US Navy is developing "stealth submarines" that
have no propellors but are equipped with artificial muscles, enabling
them them to swim silently through the water like a fish, New
Scientist says. A metre- (3.25-feet) long prototype, built by Texas A and M University at College Station, can flap its tail like a fish, the British science weekly reports in next Saturday's issue. Propellors are submarines' weak spot as they cause noise and a wake of disturbed water, leaving the vessels vulnerable to enemy sonars or aircraft. Fish, however, have evolved in favour of efficiency, using muscles to move their tail and fins and propel themselves sleekly through the water. The Texas prototype comprises a hull divided into six sections like vertebrae. They are rigid but each can be deflected with respect to their neighbouring sections. They are pushed in and out by wire "muscles" made from shape-memory alloys. These alloys are a novel mixture of strong, resilient metals that contracts when it is heated beyond a certain temperature and then expands, recovering its original shape, when it cools back down below that point. The prototype's wires, made from nitinol, an alloy of nickel and titanium, are electrically heated, which causes them to shorten and thus pull the section in. A built-in cooling system then brings the wires down to below their critical temperature, which, with help from a spring, causes them to expand and thus push the section out again. By carefully controlling the heating and cooling and coordinating the movements of each section, the prototype can be made to wriggle forward, fish-like. The top rate, so far, is five tail-flaps a second, although the researchers are tight-lipped about what speed that gives, New Scientist says. "Initially, we are focussing on unmanned water vehicles," it quotes one of the development team, Othon Rediniotis, as saying, adding that the potential is there to make a bigger version that would be manned. One of the biggest challenges is finding a power source. Rediniotis is interested in clean, light and silent sources such as fuel cells and hydrogen to drive the alloy actuators. |
 The Texas prototype comprises a hull divided into six sections like vertebrae. They are rigid but each can be deflected with respect to their neighbouring sections. They are pushed in and out by wire "muscles" made from shape-memory alloys.    |
 Royal Navy's Future Carrier  H.M.S. Vanguard  Astute Class |
Navy's Stealth Submarine will rule the oceans. A new £1.2 billion Royal Navy submarine which from the English Channel is able to detect the QE2 cruise liner leaving New York Harbour was unveiled yesterday. The Astute, the first attack submarine to be built in almost two decades, is the "most stealthy in the world" and will put the Navy at the top of the "Premiership", commanders said. At a tie when morale is suffering, the launch next month of the Navy's biggest ever hunter-killer submarine will also give hope that the service can provide considerable punch anywhere in the world. With threats in the next decade more likely to come from Islamic terrorism the submarine will be able sit off coasts undetected listening to mobile phone conversations. It also has the ability to insert Special Forces bny mini submersibles into enemy territory where they can direct the boat's deadly Tomahawk missiles with a range of 2,400 miles. "It will feel like we have won the Premiership when the Astute is handed over to the Navy. We will be the Manchester United of the submarine nations". Capt. Mike Davis-Marks, a submariner of 25 years, told the first journalists allowed on board the boat yesterday. Three of the Astute-class boats will be built by BAE Systems for £3.6 billion but the project is £700 million over budget and three years late. The boat has more than double the armoury of the Trafalgar it is replacing, and is able to carry 38 Tomahawk missiles with a range of 1,400 miles and Spearfish torpedoes capable of destroying a warship. If it could find anyway of being self-sufficient in food, the submarine, theoretically, could remain submerged for 35 years as it's nuclear reactor does not need refuelling and it can produce drinkable water by an onboard desalination plant. But life for the 98 crew has only improved to the point that the submariners have a tiny bunk space each, rather than sharing, and can watch films on a plasma television. The Astute will carry the latest Block 4 Tomahawk smart missiles that can loiter over a target and can be re-programmed in mid flight by commanders. "It can also find out what is ghoing on and report back to op commanders without anyone knowing we have been there", said Capt.Denis-Marks "because of it's covert nature the politicians like them as you can up the ante when you want or withdraw without anyone knowing you have been there." At 7,200 tonnes the Astute is the biggest British Nuclear attack submarine ever built, although it is half the size of the Trident nuclear submarines at 16,000 tonnes. It is also extremely quiet for it's size, making less noise than a small whale, and likely to be detected only by another British submarine. It is also the first submarine not have a conventuional periscope. Instead a fibre-optic tube equipped with infra red and thermal imaging pops aboe the surface for 3 seconds, does one rotation and then feeds an image in colour that can then be studied at leisure. The nuclear power plant has the acoustic signature of a torch battery and is the size of a family car. The submarine has been built at BAE Systems facility in Barrow-in-Furness, Cumbria, where Navy submarines have been made since 1901. It is due in active service late next year. |