A2: The Hydrogen-Powered Hypersonic Airliner
Images courtesy of Nick Kaloterakis for Popular Science
Flying will never be faster — or greener. That's the message Reaction Engine hopes its customers will take to heart after riding the hydrogen-powered A2. Supported in part by a grant from the EU's Long-Term Advanced Propulsion Concepts and Technologies project (Lapcat), the Mach-5, or 3,400 mph, A2 concept is in many ways the spiritual successor of the late Concorde. It differs in two important respects: range and engine efficiency.
As Popular Science's Michael Belfiore reports, the A2 is designed to carry up to 300 passengers from Brussels to Sydney in under 4 hours. The speedy airliner will benefit from a 2-mode engine — turbojet and ramjet propulsion systems — that will make it both extremely efficient at slow speeds and able to reach top speeds with great ease. Used in quick succession, these 2 modes allow the A2 to seamlessly shift from Mach-2.5 to Mach-5; a cooling system wrapped around the engine — which includes an extra turbine compressor — prevents the turbines from getting excessively hot.
Aside from the sheer challenge of designing the final craft, Reaction Engine's engineers will have to find a way of producing hydrogen fuel on a large scale without emitting carbon dioxide. Indeed, it may be too much to hope to have a truly "zero emissions" aircraft in the near future; nevertheless, if Reaction Engine succeeds in pulling this off, its engineers will have gone a long ways towards making flying a much cleaner affair.