A hypersonic aircraft three times faster than Concorde is a step closer to reality, manufacturers say. Lockheed Martin says it is close to developing a military plane that flies at Mach 6 – six times the speed of sound, which travels at around 762mph (1,236km per hour).

The technology to create such aircraft has been discussed for years, but now the firm’s engineers are said to be close to making a breakthrough.

The planes could work by burning fuel in a stream of air compressed by the forward thrust of the aircraft.

This is different to a regular jet which uses fan blades to compress air.

Orlando Carvalho, head of Lockheed’s aeronautics division, said “much more rapid” progress is now being made, but lots of work still lies ahead.

The aircraft – currently known as the SR-72 – could enter service in the 2030s.

Chairman Marillyn Hewson said: “We’re proving a hypersonic aircraft can be produced at an affordable price.

“We estimate it will cost less than $1bn to develop, build and fly a demonstrator aircraft the size of an F-22.”

Concorde’s materials meant that it could not travel faster than Mach 2. The SR-72 will get around this by being covered in ceramic tiles similar to those which covered the Space Shuttle.

Rumours of such an aircraft have been circulating for years – in 2014 loud bangs were reported over New York State.

Some speculated that it was an experimental jet engine being tested.

Concorde was introduced in 1976 and operated until 2003.