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 invented by the British during 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 U-2 spy plane, in 1954, and 10 years later they unveiled the Lockheed Blackbird. Both planes were designed...