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SR-71 Spy Plane: How Slow Can The Fastest Plane on Earth Go?

SR-71 Spy Plane
Image: Creative Commons.

For many aviation enthusiasts, the SR-71 spy plane, also known as the SR-71 Blackbird, was perhaps the most iconic aircraft of the Cold War.

A long-range, high-altitude, Mach 3-plus strategic reconnaissance spy plane developed and manufactured by Lockheed Corporation, it was capable of extremely high-altitude flight and was even used by NASA. Throughout its nearly twenty-four-year career, the much-vaunted plane was considered the world’s fastest and highest-flying operational aircraft.

Not to be outdone, do take note that the Lockheed Martin SR-72, also known as the “Son of Blackbird,” is currently in development, which will likely boast even greater speeds.

According to Dario Leone at the Aviation Geek Club, “no reconnaissance aircraft in history has operated in more hostile airspace or with such complete impunity than the SR-71 Blackbird. It is the fastest aircraft propelled by air-breathing engines. The Blackbird’s performance and operational achievements placed it at the pinnacle of aviation technology developments during the Cold War.”

SR-71 Spy Plane: Designed for Low Speeds?

Many already know that the SR-71 spy plane was designed to cruise at Mach 3-plus—or more than 2,200 miles per hour—but there is one particular question that often does not get asked: What’s the slowest speed ever registered by a Blackbird?

Recounted in his book Sled Driver, Brian Shul, a former SR-71 Blackbird pilot, writes that “I was flying the SR-71 out of RAF Mildenhall, England, with my backseater, Walt Watson. We were returning from a mission over Europe and the Iron Curtain when we received a radio transmission from home base.”

As for what happened next, Rex Lowe, a former USAF Staff Sergeant, explains in detail on Quora.

“The aircrew was asked to make a low level pass of a British airfield where cadets were training. Having difficulty actually sighting the field, though navigation was dead on, the pilot, Brian Shul, realized the aircraft was below advertised flying airspeed, he lit the burners and darted off,” he said.

SR-71 Spy Plane: Under Speed Limit

Here comes the reading that likely marks the slowest speed ever flown by a Blackbird.

“The backseater later indicated slow speed of 155 knots, pilot saw 152 knots or 175 mph. The aircraft at that point was gently floating down, control certainly would have been lost completely had not Shul firewalled the throttles,” Lowe continued.

After landing the Blackbird, Shul noted that “we were both certain he was reaching for our wings. Instead, he heartily shook our hands and said the commander had told him it was the greatest SR-71 fly-past he had ever seen, especially how we had surprised them with such a precise maneuver that could only be described as breathtaking. … Walt and I both understood the concept of ‘breathtaking’ very well that morning and sheepishly replied that they were just excited to see our low approach.”

SR-71 Engine from Pratt & Whitney J58

SR-71 Engine from Pratt & Whitney J58

SR-71 and F-16

SR-71 and F-16. Image: Creative Commons.

SR-71 Blackbird aircraft

A direct front view of an SR-71 Blackbird aircraft after landing from its 1,000th sortie.

Ethen Kim Lieser is a Washington state-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek, and Arirang TV. Follow or contact him on LinkedIn.

Written By

Ethen Kim Lieser is a Washington state-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek, and Arirang TV.

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