US Patent and Trademark Office has approved Airbus’ proposed hypersonic aircraft, which would be able to travel at 4.5 times the speed of sound.

If the aircraft is ever developed, it is expected to reduce travel time from Paris to Tokyo to less than three hours, the company said in its patent.

The ‘ultra-rapid air vehicle and related method for aerial locomotion’ aircraft will be powered by normal jet engines for take-off, and then Ramjet engines will be ignited to take the aircraft up to altitudes of around 30km.

"The new aircraft reduces the noise of the sonic boom by being near-vertical like a rocket during cruising."

The speed of the proposed aircraft will be double that of previous supersonic versions, Aerospatiale and British Aircraft-built Concorde, and Voronezh Aircraft Production’s the Tupolev Tu-144, reported CBCnews.

According to Airbus, the new aircraft reduces the noise of the sonic boom by being near-vertical like a rocket during cruising to altitudes of up to 35,000m.

The patent stated: "This noise has been the main limit, if not the only one, preventing the opening of lines other than transatlantic ones for the Concorde aircraft."

Airbus spokesman was quoted by Reuters as saying: "Airbus Group and its divisions apply for hundreds of patents every year in order to protect intellectual property.

"These patents are often based on R&D concepts and ideas in a very nascent stage of conceptualisation, and not every patent progresses to becoming a fully realised technology or product."

The European aircraft maker is currently working on hypersonic projects with Japanese partners, and the other in collaboration with Russian and Australian partners. The company intends to achieve aircraft speeds of up to Mach 6.