segunda-feira, novembro 15, 2004

Quem levantar a grimpa...

in http://www.guardian.co.uk/usa/story/0,12271,1350964,00.html?gusrc=rss

US to deploy hyper-missiles

Anywhere on Earth could be targeted 'within two hours'

Robin McKie and David Smith
Sunday November 14, 2004
The Observer

American scientists are developing hypersonic cruise missiles that will fly 10 times faster than current rockets, penetrate concrete armouring and could be launched from any site in the world.

The missiles would have a range of 9,000 miles, more than a third of Earth's circumference and be able to reach their targets within two hours. First prototypes are expected to be tested next year, though the missile is not expected to be deployed until the end of the decade.

'If someone is messing with us - or Britain - from far away, we could whack them straight away,' said Preston Carter, an aerospace engineer at Lawrence Livermore National Laboratory, in California.

The new missiles will exploit supersonic combustion ramjet - or scramjet - technology. Nasa engineers will tomorrow attempt to fly a robot X-43A scramjet over the Pacific at speeds around 7,200 mph, 10 times the speed of sound.

The flight will be crucial in demonstrating the feasibility of hypersonic travel. Most media attention has focused on its commercial exploitation for jets that could travel from London to Sydney in two hours. The prime aim is to create hypersonic rockets that would replace current cruise missiles.

'The new missiles could strike pretty much anywhere within a couple of hours,' said Graham Warwick, Americas editor of Flight International . 'Current cruise missile have to be carried on a B52 bomber. That involves planning and takes at least 24 hours. The military want a quick solution, so if they knew bin Laden was sipping coffee at a cafe they could get a bomb on target in two hours.'

Scramjets work on the same principle as all jets, by igniting fuel in compressed air and using the expanding gases to propel the aircraft. Standard turbojets use fans to compress the air: scramjets use a plane's forward motion alone to bring air into the combustion chamber and require an initial boost from a rocket.

The entire aircraft then becomes an enormous scoop that receives air which is compressed and injected - and ignited - with a chemical called silane before hydrogen fuel is added. The feat compares to 'lighting a match in a hurricane', says Nasa.

'We'll see a military application initially as a "bunker buster" that would hit its target and bore into the ground before exploding,' said Carter.'

'We are talking about the ability to strike more cost-effectively. If the US has to deploy troops to the other side of the world, it is expensive. This may keep enemies in check and act as a deterrent.'