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The next generation of Kiwi travellers could be breakfasting in Auckland and lunching in London, if a planned hypersonic passenger jet gets the green light.

British firm Reaction Engines' proposed A2 jet could whisk passengers around the globe at a dizzying 6100km/h, about five times the speed of sound.

The A2 project - ponderously titled Long-Term Advanced Propulsion Concepts and Technologies (LAPCAT) - was funded by the European Space Agency, which challenged scientists to produce a commercial jet using space-travel technology.

The jet could cut the flight time from Auckland to Europe to as little as five hours, potentially opening up the Continent to Antipodean day-trippers.

A Boeing 747-400 takes the better part of 24 hours to fly from Auckland to London, at a top speed of 1000km/h.

A New Zealand-Europe round trip on the 300-passenger A2 would probably cost about the same as a business-class ticket, about $8800, Britain's Guardian reports.

Aside from being fast, the new jet would also be clean and green, burning a liquid-hydrogen fuel that gives off water vapour and nitrous oxide (laughing gas), instead of polluting carbon emissions. At 142 metres in length, the A2 would be about twice the length of the Airbus A380, the largest airliner in service today.

The term hypersonic flight relates to speeds above Mach 5, a velocity at which friction can cause an aircraft's wings to heat to 1000C.

Unfortunately, attaining such external temperatures would mean doing without windows, but designers may put flat-screen televisions where the windows would be, giving the impression of seeing outside.

Despite being capable of travelling at twice the speed of its predecessor, Concorde, the A2 would be quieter, Reaction says. Senior engineer and managing director Alan Bond said the A2 could be here within 25 years.