WHAT’S FASTER THAN AN SR-71? Skunk Works Hints At SR-72 Demonstrator Progress.

Four years after revealing plans to develop a Mach 6 strike and reconnaissance aircraft, Lockheed Martin says hypersonic technologies are now sufficiently mature to enable progress towards a flight demonstrator.

The company’s secretive Skunk Works unit has been working since at least the early 2000s on the basic building blocks for an operational hypersonic vehicle and in 2013 revealed to Aviation Week it was developing a scaled demonstrator for the SR-72, a proposed successor to the U.S. Air Force’s long-retired Mach 3 SR-71 Blackbird spy plane. However, details on any subsequent progress have been scarce since this initial plan was unveiled.

I’d expect them to stay scarce, even after the SR-72 takes to the skies.