A BRITISH team has designed a hypersonic passenger aeroplane that could one day fly passengers between Europe and Australia in less than five hours.

The A2 aeroplane was designed by Culham-based Reaction Engines and would carry 300 passengers at a top speed of almost 4,000mph.

The company says the aircraft could be operating within 25 years and ticket prices would be comparable with an existing business class ticket, about £3,500.

The LAPCAT (Long-Term Advanced Propulsion Concepts and Technologies) project is being funded by the European Space Agency (ESA) to encourage companies to push the boundaries of commercial air travel using technology more commonly associated with space travel.

Reaction Engines says the A2 is capable of sustained travel at Mach 5, or 3,800 mph, more than twice the speed of Concorde.

At 143 metres long it is roughly twice the size of the biggest current jumbo jets. It runs on a liquid hydrogen Scimitar engine being developed by Reaction Engines that is based on existing technology.

Alan Bond, managing director of Reaction Engines, said: "The A2 is designed to leave Brussels international airport, fly quietly and subsonically out into the north Atlantic at mach 0.9 before reaching mach 5 across the North Pole and heading over the Pacific to Australia.

"The flight time from Brussels to Australia, allowing for air traffic control, would be four hours 40 minutes. It sounds incredible by today's standards but I don't see why future generations can't make day trips to Australasia.

"Our work shows that it is possible technically; now it's up to the world to decide if it wants it."

The ESA's website says that hypersonic flight is generally considered to begin at Mach 5, when aerodynamic heating becomes important in aircraft design, with temperatures in the boundary layer and on the surface of an object reaching 1,000 degrees Centigrade.

Hypersonic flight is not new. The first man-made object to reach hypersonic speeds was the two-stage US "Bumper" rocket, assembled from a captured German V-2 rocket in 1949.

Astronauts and cosmonauts have all reached hypersonic speeds while passing through the atmosphere on their way to or from orbit. Current research, however, focuses on sustained hypersonic flight within the Earth's atmosphere.

The ESA says that the Space Shuttle punches through the atmosphere as quickly as possible on its way into orbit, but the LAPCAT project is focusing on an aircraft that would remain well within the Earth's atmosphere throughout its flight.

Whereas the Shuttle uses the thrust of its engines to fight the force of gravity, a hypersonic vehicle would use the aerodynamic lifting force generated on its wings and fuselage.

This vision of sustained hypersonic flight requires air-breathing engines, which are highly efficient because they scoop oxygen from the atmosphere rather than from an onboard tank.