Image caption The concept plane is due to begin flight trials in 2011

The Ministry of Defence has unveiled its prototype unmanned combat air vehicle (UCAV).

Taranis is a concept design for a long-range strike plane that has taken over three million man hours to produce.

Defence Minister Gerald Howarth said it was a "truly trailblazing project" and featured "the best of our nation's advanced design and technology".

The aircraft is due to begin flight trials early next year.

Named after the Celtic god of thunder, Taranis is the first step in the development of unmanned strike aircraft, capable of penetrating enemy territory.

Unmanned aircraft carrying weapons are already used in service, such as the MQ-1 Predator which carries Hellfire missiles, although these are only suitable for use where the airspace is under allied control.

"This is the next generation of combat aircraft and flight trials will begin next year," Sqn Ldr Bruno Wood told BBC News.

"It's a technology demonstrator that could be used as a testbed which may form further potential solutions to the RAF," he added.

Drop the pilot

The issue of "writing the pilot" out of the aircraft equation has long been a controversial topic, more so since the first unmanned aerial vehicle (UAV) went into active service.

It is accepted that the most vulnerable part of a plane is the pilot. While the airframe is capable of pulling multiple Gs - the gravitational force exerted on a body when standing on the Earth at sea level - the maximum safe level for a pilot, even when wearing a protective G-suit, is 8 or 9, above which they will lose consciousness.

Also, many anti-aircraft missiles are designed to explode near the cockpit, showering the vulnerable pilot with high-speed shrapnel that can cause death or injury.

Peter Felstead, editor of Jane's Defence Weekly, told BBC News that the development of UAVs paralleled the development of the first manned aircraft during World War I.

"First they were used for reconnaissance, then they were armed for bombing and ground attack missions and they eventually became air-to-air combat craft," he said.

"This is the first step for the UK. This isn't an aircraft that will go into service, it's a tech demo, but it will prove technologies, demonstrate capabilities and inform the direction we [the UK] are going in."

'Human control'

However, Mr Felstead stressed that while we would see greater development of ground attack UAVs, there would always be the need for a pilot with a "Mk I eyeball" when it came to air-to-air combat.

"If you have, say, an airliner that is reportedly hijacked, you are going to need that human factor to evaluate just what's going on with the plane, what he can see through the windows and everything else. That's not something, for now, that can be done remotely."

The MoD also stressed that all weaponised UAVs were under human control.

"Should such systems enter into service, they will at all times be under the control of highly trained military crews on the ground," it said in a statement.