Skylon

Reaction Engines's Synergetic Air-Breathing Rocket Engine (SABRE) engine has passed a major milestone, as a key component handled conditions equivalent to an airspeed of Mach 5 (3,704 mph, 5,961 km/h).

The British government announced on Tuesday that it has authorized an investment of £60 million in Reaction Engine Ltd’s Skylon spaceplane after a successful feasibility test managed by the European Space Agency.