Hypersonic travel that could propel people from London to Sydney in just two hours is one step closer to reality, following a successful test.

The project, which saw US and Australian military scientists combine resources, is on track to launch in 2018 after its latest engine trial hit the target speed of Mach 7.5 - more than seven times the speed of sound.

It could revolutionise global air travel and prove cost-effective access to space, Alex Zelinsky, the chief Australian scientist working on the project said.