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SR-91: A Real Mach 6 Spy Plane or Just Internet Rumor?

SR-91 Aurora
SR-91 Aurora. Image Credit: Rodrigo Avella

The SR-91 seems to dazzle the imagination with its rumored speeds. And yet, it seems to never have been real: Some airplanes, no matter how impressive and badly needed, just don’t make it to production. Sometimes a prototype is even built, and it may even take a test flight, but it enters the “valley of death,” a phase of defense acquisition in which the manufacturing program becomes a bridge too far as costs mount up and the project gets canceled. This is what likely happened to the SR-91 Aurora spy plane.

Black Program Kept the Concept Under Wraps

The idea was to replace SR-71 Blackbird, the old stalwart that became more and more expensive to maintain – to a tune of $200 to $300 million a year to fly on a regular basis. The SR-91 was a special access “black” program that was hidden from public view. Most defense budgets did not even mention it by name. The SR-91 was supposed to be able to reach speeds of MACH 4 to 6 at 90,000 feet to easily evade enemy sensors, radar, and surface-to-air missiles.

Just a Fleeting Glimpse of the Name Aurora

The airplane became more of a myth than reality. It entered into the lexicon when it appeared in a 1985 Department of Defense budget proposal that mentioned the name Aurora when it discussed other spy planes such as the SR-71 and U-2 ultra high-performing recon birds.

The British May Have Spilled the Beans

The SR-91 also became a topic of discussion through the British Ministry of Defense when a report from the MoD in 2006 mentioned the possibility of a new American spy plane program that would fly at an extremely fast speed and high ceiling. But the existence of the new airplane seemed to be more of a “hypothesis” rather than a real acquisition program.

SR-91 Were There Witnesses?

But one person claimed to have seen a triangular-shaped airplane over the North Sea by an offshore petroleum engineer in 1989. That sighting does not make sense because the Aurora would likely have been flying too fast and too high for human eyes to spot. Other people speculated that a new spy plane could have caused loud sonic booms called “sky quakes” when flying over Los Angeles in the early 1990s. Under this scenario, the Aurora could have been flying from Groom Lake, Nevada (also known as Area 51).

Social Media Sleuths Would Have Spotted It

These days military aircraft spotters on social media report sightings of new platforms all the time. The Aurora, had it existed, would have likely been observed and hyped online at some point after 2006. Moreover, the Aurora moniker may have been a codename for the B-2 Spirit stealth bomber.

It Was Likely Confused for Another Airplane

This is the most plausible scenario – the Aurora was actually another plane and not a new hypersonic spy aircraft. There just are not enough witnesses or corroborated sightings to deem it a reality. The Aurora program may have also been cancelled early on before anything ever flew.

SR-91 – Was It Redundant Anyway?

The Air Force may have determined that advanced spy satellites could do the same work as ultra-fast recon planes. This would make Aurora face the chopping block to save money. And the U-2 is still flying fine and conducting missions over Ukraine to snoop on new intelligence data about the battlefields in the Russo-Ukraine War. So, it seems the Aurora is a hypothetical concept that probably never made it past the drawing board.

Some research and development money may have been spent, but no airplane likely existed beyond the conceptual stages.

Now serving as 1945’s Defense and National Security Editor, Brent M. Eastwood, PhD, is the author of Humans, Machines, and Data: Future Trends in Warfare. He is an Emerging Threats expert and former U.S. Army Infantry officer. You can follow him on Twitter @BMEastwood.

Written By

Now serving as 1945s New Defense and National Security Editor, Brent M. Eastwood, PhD, is the author of Humans, Machines, and Data: Future Trends in Warfare. He is an Emerging Threats expert and former U.S. Army Infantry officer.