Mysterious hypersonic SR-72 demonstrator spotted in California

Lockheed Martin's Advanced Development Program (ADP), better known as “Skunk Works,” might be further along in the development of their hypersonic SR-72 than the company has previously let on. A proposed hypersonic reconnaissance and strike aircraft, the SR-72 is the successor to the infamous cold war spy plane the SR-71 Blackbird, which was retired by the USAF back in 1998. Earlier this year in June the company announced that they were confident about starting production of the SR-72 “very soon,” and now a source has told Aviation Week that they spotted a small demonstrator aircraft landing at Skunk Works facilities in Palmdale, California.

The reported sighting corresponds with announcements from Lockheed’s executives who recently said that they were working on a combined-cycle TBCC engine that uses elements of both a turbine and a scramjet to achieve hypersonic speeds, something they tested with partner Aerojet Rocketdyne between 2013 and 2017. Two combined-cycle engines are planned to power the SR-72, which is designed to be about the same size of the SR-71 and could achieve first flight in the late 2020s.

While the main aim of the program is to create an unmanned version of the SR-72, which could act as a hypersonic spy plane or even as a high speed strike weapon, an “optionally piloted” Flight Research Vehicle (FRV) is also apparently in the works to help flight test the SR-72 design. Initially the FRV will be about the size of an F-22 and use a single combined-cycle engine for propulsion, and its development is expected to begin next year with first flights as soon as 2020. Leading up to the FRV though it’s only natural that Lockheed would be conducting ground and flight tests on even smaller demonstrators, which might explain the small aircraft that was reportedly spotted landing at their facilities in California.

According to the source one such technology demonstrator, believed to be an unmanned subscale aircraft, was observed flying into the US Air Force's Plant 42 at Palmdale, where Skunk Works is headquartered. The vehicle, which was noted landing in the early hours at an unspecified date in late July, was seen with two T-38 escorts. Lockheed Martin declined to comment directly on the sighting.

In addition to the alleged sighting, Orlando Carvalho, Executive Vice President of Aeronautics at Lockheed Martin, referenced the SR-72 program at this week's SAE International Aerotech Congress and Exhibition in Fort Worth, Texas.

"Although I can't go into specifics, let us just say the Skunk Works team in Palmdale, California, is doubling down on our commitment to speed," he said, going on to say, "Hypersonics is like stealth. It is a disruptive technology and will enable various platforms to operate at two to three times the speed of the original Blackbird... Security classification guidance will only allow us to say the speed is greater than Mach 5."

With classified military aircraft development, it has historically been the case that systems and flight testing begin years before details of the program are made public. Such was the case with the original SR-71, as well as the F-117 Nighthawk and the B-2 Spirit stealth aircraft, and now, the fact that Skunk Works is letting some information slip about the SR-72 program, combined with the possible subscale demonstrator sighting in Palmdale, it looks like the appearance of the Blackbird's hypersonic successor is only a matter of time.