US plans for hypersonic robot spy plane revealed

The unmanned SR-72 will use an engine that combines a turbine and a ramjet to reach its top speed of Mach 6 - about 3,600mph (5,800km/h). Like its predecessor, the SR-72 will be designed for high-altitude surveillance but might also be fitted with weapons to strike targets. Lockheed said the aircraft should be operational by 2030.

See the full article at BBC News