Imagine eating breakfast in Brussels and then dinner in Sydney – all in the same day. If the hypersonic AS concept plane is ever built, you may be able to do just that. Twice as long as the new Airbus A380, the A2 will carry up to 300 passengers, with rates promised to be comparable to a business class ticket. The plane will speed along at 3,900 miles per hour (Mach 5) or five times the speed of sound. That is twice as fast as the Concorde!

Modern air travel is a marvel. It’s also a source of endless delay, annoyance and planet-killing greenhouse gases. A proposed hydrogen-powered hypersonic airliner could change all that. The plane is Reaction Engines’s A2 concept, a Mach-5 (3,400mph) craft for 300 passengers funded in part by the European Union’s Long-Term Advanced Propulsion Concepts and Technologies project (Lapcat). Lapcat wants an airliner that can fly from Brussels to Sydney in less than four hours. If built, the A2 will do just that—without producing a trace of carbon emissions.

Engineers created the A2 with the failures of its doomed supersonic predecessor, the Concorde, very much in mind. Reaction Engines’s technical director, Richard Varvill, and his colleagues believe that the Concorde was phased out because of a couple major limitations. First, it couldn’t fly far enough. “The range was inadequate to do trans-Pacific routes, which is where a lot of the potential market is thought to be for a supersonic transport,” Varvill explains. Second, the Concorde’s engines were efficient only at its Mach-2 cruising speed, which meant that when it was poking along overland at Mach 0.9 to avoid producing sonic booms, it got horrible gas mileage. “The [A2] engine has two modes because we’re very conscious of the Concorde experience,” he says.

But an even greater asset than the A2’s speed is its negligible carbon footprint. It’s hydrogen-powered, so it produces only water vapor and a little bit of nitrous oxide as exhaust. And although a hypersonic jet loaded with liquid hydrogen might sound dangerous, hydrogen fuel is actually no more explosive than normal jet fuel.

Don’t look for the A2 anytime soon. The plane’s maker thinks this concept could become a reality within 25 years.

[via Popular Science]