LONDON - BRITISH engineers unveiled plans on Tuesday for a hypersonic jet which could fly from Europe to Australia in less than five hours.

The A2 plane, designed by engineering company Reaction Engines based in Oxfordshire, southern England, could carry 300 passengers at a top speed of almost 4,000 mph (6,400 kmh), five times the speed of sound.

The LAPCAT (Long-Term Advanced Propulsion Concepts and Technologies) project, backed by the European Space Agency, could see the plane operating within 25 years, the firm's boss Alan Bond told the Guardian daily.

'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,' he said.

The plane, which at 143 metres long would be about twice the size of the biggest current jets, could fly non-stop for up to 12,500 miles (20,000 km).

It operates on liquid hydrogen, which is more ecologically friendly as it gives off water and nitrous oxide instead of carbon emissions.

Passengers would have to put up with having no windows, due to problems with heat produced at high speeds.

Instead designers may put flat screen televisions where the windows would be, giving the impression of seeing outside.

Fares would be comparable with current first class tickets on standard flights, of around 3,500 pounds (S$9773).

The flight time from Brussels to Australia would be four hours and 40 minutes.

'It sounds incredible by today's standards but I don't see why future generations can't make day trips to Australasia,' he said.

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