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When an inlet unstart hindered the SR-71 crew from exceeding Mach 3.2

by Till Daisd
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“If they hadn’t had the unstart when they were going through the gate, the record speed would’ve been higher. Their goal was to make 2200 mph,” David Peters former SR-71 Blackbird pilot

The SR-71 Mach 3 + spy plane, which was developed from the Lockheed A-12 and YF-12A, made its first flight on December 22, 1964. It was first delivered to the 4200th (later 9th) Strategic Reconnaissance Wing at Beale Air Force Base, California, in January 1966.

For almost two decades, the SR-71 held the record for being the fastest and highest-flying operational aircraft in the world. It could cover 100,000 square miles of the Earth’s surface per hour from 80,000 feet. In 1976, the SR-71 Blackbird was also the preferred aircraft for commemorating the bicentennial of the United States. Officials decided to try breaking a few records with the famous reconnaissance aircraft as a way to celebrate.

In July of that year, retired Maj. Gen. Eldon (Al) Joersz, the pilot, and retired Lt. Col. George Morgan, the reconnaissance systems officer (RSO), set a world absolute speed record for jet-powered airplanes with a speed of 2,193 mph, as reported by Angela Woolen in the article SR-71 pilots, crew relive absolute speed record. The record is still in effect today.

Retired Maj. Gen. Eldon Joersz, a former pilot, and retired Lt. Col. George Morgan, a former reconnaissance systems officer, sit inside the cockpit of the SR-71 Blackbird they flew when setting the world absolute speed record for jet-powered aircraft on Jul. 28, 1976. The two were at the Museum of Aviation in Warner Robins, Georgia, for the 40th anniversary of the historic flight. (U.S. Air Force photo/Tommie Horton)

The Blackbird that set the speed record, SR-71 #958, is currently on display at the Museum of Aviation, which is located close to Warner Robins, Georgia. It’s noteworthy that Joersz and Morgan encountered an inlet unstart during the record-breaking event, but it didn’t stop the iconic Blackbird from breaking the absolute speed record.

SR-71 pilot David Peters explains;

‘If Joersz and Morgan had just a normal unstart without a burner blowout, it probably didn’t slow them down much but they certainly would have had the record higher without it.’

They could have exceeded 2,193 mph if not for the inlet unstart that momentarily jammed an engine. This note is from George Morgan: ‘Al and I had the ACTUAL speed record. 2200 indicated in our equipment aboard 958!

‘Theirs…. 2193….NAH!’

Peters explains;

“Just to clear up a couple of points, first, an unstart does not usually cause the engine to shut down. In this case, it was just an unstart of the inlet, which can be recovered rather quickly. Second unstarts were much more likely in the 2.6 to 2.9 range, especially in the climb. High Mach unstarts were much more rare.”

That record-breaking run could have been achieved by any SR-71 with any crew. However, the commander would have chosen the most dependable crew available. He chose George Morgan and Al Joersz to board the aircraft. They truly didn’t want to draw attention to the Blackbird in the early SR-71 days. As part of the United States 200th anniversary celebrations, President Ford inquired as to whether an SR could make the speed run. Commanders of SR-71 never refused a presidential request.

The aircraft achieved the first of its two passes at a speed that was significantly faster than what was needed to break the record. One of the engines shut down just before the second pass began. The plane was well beyond the start line before the engine could be started again. The engine did recover from the unstart.

Capt. Al Joersz, the record-setting pilot, said, “By the time we’d gone through the checklist, we’d already passed the second gate, thus officially starting the run. Still, we exited the gate at Mach 3.2.”

Peters concludes:

“If they hadn’t had the unstart when they were going through the gate, the record speed would’ve been higher. Their goal was to make 2200 mph.”

However, after the inlet unstart, Joersz and Morgan could’ve pushed the Blackbird to the limit and gone Mach 3.3, but in 1976, they didn’t want anyone to know how fast the SR-71 could go. It was still classified. For this reason, the US Air Force (USAF) chose to set the speed record “very carefully” avoiding disclosing how fast the SR-71 could really go.

Check out the Habubrats SR-71 and Born into the Wilde Blue Yonder Facebook pages for further Blackbird photos and stories.

Photo by U.S. Air Force and Lockheed Martin

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