By Paul Rincon
BBC News science reporter
Images of the UK's first prototype stealth surveillance aircraft have been unveiled.
The unmanned vehicle, which has been built by BAE Systems, is known as the Corax, or as the Raven.
The Corax bears some resemblance to a cancelled US military spy plane called DarkStar, analysts have said.
Jane's International Defence Review said the unmanned aircraft "indicated a new direction in combat vehicles for the UK's armed forces".
Bill Sweetman, the magazine's aerospace and technology editor, said Corax could represent one member of a family of stealthy aircraft based around a similar central body but using different outer wings optimised for different missions.
"If you look at that Corax shape, it's very reminiscent of something that's designed to fly fairly high, fairly slow and have quite a long endurance. It looks rather typical for a surveillance aircraft," he told the BBC News website.
"But if you take those long outer wings off and put on shorter swept wings, you have a somewhat faster aircraft that would be more of a penetrating strike platform."
The US and British armed forces believe these pilotless planes will play an increasingly vital role on 21st Century battlefields.
The UK has reportedly scrapped plans for a future manned combat aircraft and is working closely with the US on "Project Churchill".
This is an effort focused on combining ideas about the command and control of unmanned combat air vehicles (UCAVs) from 2015 onwards.
The Corax prototype has been built to investigate the stability, control and performance of the design, which is said to maximise all-round stealth.
Mr Sweetman said the aircraft appears to be a small-scale demonstrator powered by a commercially available model aircraft jet engine and with a 5-6m (16-19ft) wingspan.
Stealth technology refers to a variety of techniques used to render aircraft, ships and missiles less visible - and ideally invisible - to radar.
The prototype Corax was first flown in 2004 after a 10-month development programme.