The design was to use liquid hydrogen as a fuel, which can achieve twice the specific impulse of kerosene, and the cryogenic fluid can also be used to cool the vehicle and the air entering the engines via a precooler.

Alan Bond, managing director of Reaction Engines, said "Our work shows that it is possible technically; now it's up to the world to decide if it wants it.

"[1] The developers said in 2009 that it would be able to fly from Europe to Australia in under five hours,[2] compared to around a complete day of travel with normal aircraft.

The heat generated by the hypersonic airflow over the body puts constraints on window design which would make them too heavy.

One solution Reaction Engines proposed was to install flat panel displays, showing images of the scene outside.