Super jet could cut flight times in half

A new supersonic jet could cut flight times by about half, taking Sydney passengers to LA in less than seven hours.

A new supersonic plane backed by British billionaire Richard Branson could cut flight times in half. (AAP)

A new supersonic plane backed by British billionaire businessman Richard Branson could cut flight times in half, landing Sydney passengers in Los Angeles in less than seven hours.

A prototype of the XB-1 Supersonic Demonstrator, nicknamed the "Baby Boom", will be unveiled by Boom Technologies and Mr Branson's Virgin Galactic at a hangar in Colorado on Wednesday.

Boom says the plane will be the fastest civil aircraft ever built. A prototype one third the size of the planned airliner is being built with the help of Virgin Galactic with subsonic flight testing planned for late 2017.