PARIS (Reuters) - Airbus (AIR.PA) has won a patent for a hypersonic plane, but Concorde's hydrogen-powered successor is unlikely to leave the drawing board any time soon.
The European planemaker's proposal would slash the journey time from Paris to Tokyo to under three hours, from 12 hours.
The idea, first published in 2011, is to use three different kinds of engine power to hop, skip and jump above the atmosphere, yet taking off from a regular runway.
It has now won approval from the U.S. Patent Office.
The concept comes as commercial space companies such as Virgin Galactic pursue plans for low-level space flights.
Its "gothic delta wing" echoes the elegant curves of Concorde.
But Airbus dampened any hopes of a quick return to the days of the Anglo-French supersonic jet, which was taken out of service in 2003 due to high operating costs.
"Airbus Group and its divisions apply for hundreds of patents every year in order to protect intellectual property," a spokesman said by email.
"These patents are often based on R&D concepts and ideas in a very nascent stage of conceptualization, and not every patent progresses to becoming a fully realised technology or product."
By climbing almost vertically, the new "ultra-rapid air vehicle's" designers hope to avoid the supersonic boom that hampered Concorde's deployment beyond the North Atlantic, where it flew at twice the speed of sound for over 20 years.
The hypersonic plane would take off using a regular jet engine, before rocket boosters kick in to start a sharp ascent, sending the plane soaring above the atmosphere.
Ramjet engines, currently used in missiles, would then take the plane up to altitudes of some 30km as the plane cruises at speeds up to Mach 4.5 (approximately 4,780 km), or 4.5 times the speed of sound.
The turbojets would reignite to enable landing.
Announcing a similar proposal in 2011, Airbus Group, then known as EADS, said it would take 30-40 years to enter service, if at all. But the patent is designed to put down a marker for technology that could be useful in other developments.
Airbus says it is working on two hypersonic projects, one with Japanese partners and another with Russian and Australian involvement, with the aim of conquering speeds up to Mach 6.
(Reporting by Tim Hepher and Victoria Bryan; Editing by Mark Heinrich)