A2

"The vehicle is intended to have about 20,000 km range and good subsonic and supersonic fuel efficiency, thus avoiding the problems inherent in earlier supersonic aircraft. The top speed is projected to be Mach 5+. It calls for the use of liquid hydrogen as a fuel, which has twice the specific energy of kerosene, and can be used to cool the vehicle and the air entering the engines via a precooler.
The developers say it would be able fly from Brussels to Sydney in about 4.6 hours. The cost of a ticket is intended to be roughly business class level."

“Our work shows that it is possible technically; now it's up to the world to decide if it wants it."

— Alan Bond, managing director of Reaction Engines Limited (in Wikipedia)

EU QUERO!!! E porque é que me lembrei disto agora? Porque era fixe que eles tivessem isto pronto para a semana para assim, se por cá estivesse a chover mais uma vez durante o fim de semana eu poder pegar num destes e ir tomar uma cafezada à antiga Mistral na Praia de Carcavelos... Não sei.. Assim de repente parece-me uma boa ideia..