Boom Supersonic has already received 76 orders for its commercial supersonic passenger aircraft, and it doesn’t actually exist yet.

Boom Supersonic, a start-up backed by Richard Branson, has revealed a new design for its XB-1 Supersonic Demonstrator jet prototype at the Paris Air Show this week.

Boom promises the jets will significantly reduce flight time on intercontinental routes (you’d be able to travel from Sydney to Los Angeles in six hours, and from London to New York in less than four hours), for prices that are comparable to current business-class fares.

BBC News reports the plane is expected to make its first test flight by the end of 2018.

Blake Scholl, Boom’s founder and chief executive, told reporters at the Paris air show that the design of the prototype has passed a performance and safety review.

Boom’s plane ditches the afterburner engine used by the failed Concorde, which guzzled fuel and was known for being noisy.

“By using a modern turbofan engine like Boeing and Airbus, you can make the aircraft both quieter and significantly more fuel efficient,” Scholl told BBC News.

The company claims that a ticket on the London-New York route will cost roughly AU$6,500 return, about one third of what a Concorde ticket used to cost.

While industry observers are skeptical that Boom can deliver on its promises, the company has raised the money required to build and fly the prototype, and says it has already received orders for 76 of the jets across five different airline customers.

“Airlines are excited for something new and different to offer their passengers,” Scholl said.

Virgin founder Sir Richard Branson announced last year that he would buy the first 10 passenger jets made by Boom, and will provide manufacturing and engineering services and flight test support to Boom through his Virgin Galactic space travel venture.

“I have long been passionate about aerospace innovation and the development of high-speed commercial flights,” he said in a statement.

If all goes to plan, the ‘quiet Concorde’ could be travelling across the Atlantic at supersonic speeds by 2023.