11 June 2004
11 June 2004
The Swedish Navy is testing out a CFRP “Visby” ship which is believed to be the most ""invisible"" yet.
The Visby is designed to have a low key radar signature. Ever since radar was invented by the British during World War II, the military have been looking at ways to avoid detection, sometimes with success, but now it seems that naval architects have come up with another solution.
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. 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.
The Visby is constructed almost entirely of carbon fibre, based on construction models used in motor sports to make the chassis of Formula One cars and the hulls of racing yachts. It is 73 metres in length and carries a crew of 43 travelling at travel at an average speed of 35 knots. It's Hull, made of CFRP brings the total cost to around 100 million (GBP).
With carbon fibre being much lighter than steel, the Visby weighing 600 tonnes is half the weight of a conventional corvette.
John Nilsson, one of the designers, said: ""We are able to reduce the radar cross section by 99%. That doesn't mean it's 99 percent invisible, it means that we have reduced its detection range."" 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.
The Royal Navy and the US Navy both have plans of their own for similarly futuristic ""stealth"" ships. But a MoD spokesman questioned the ""survivability"" of ships made of carbon fibre, and also doubted whether they could be cope with ocean conditions. The Royal Navy's ship will not be made out of carbon fibre
Mr Nilsson said the Visby was only designed for littoral, or coastal warfare. 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 sister ship of the renowned passenger ferry Vision of the Fjords takes sustainability one step further. A catamaran constructed from carbon fibre composite that runs entirely on batteries, Future of the Fjords will offer sightseeing with a minimum of environmental impact.
Toho Tenax is introducing a high-tensile, highly shock-resistant prepreg that incorporates carbon fibre developed for aerospace applications and carbon nanotubes (CNTs).
NTPT is collaborating with the Ecole polytechnique fédérale de Lausanne - Swiss Centre of Technology (EPFL) and other partners to research discontinuous fibre composite tubes for high performance applications.