The SR-71A #61-7959, the only “Big Tail” Blackbird ever-built

SR-71A #61-7959 came off the assembly line like any other Blackbird, but it was chosen as the platform for a new set of sensor equipment to be carried in a nine-foot extension from the rear of the aircraft

The striking photos in this article showcase a unique Blackbird, SR-71A #61-7959, best known as “Big Tail.”

Aircraft #959 left the assembly line like any other SR-71 when it was rolled out on Aug. 16, 1965, but in 1975, it was selected to test a new suite of sensors housed in a nine-foot extension added to the jet’s rear.

When the SR-71s began flying operational missions during the Vietnam War, some flights had to be scrubbed because of bad weather. This, in turn, prompted experimental trials of an additional camera.

There was also a concern that, in the future, ground-based defenses might be able to target the SR-71 from the rear because it lacked rear-facing defensive countermeasures.

In 1974, the Air Force determined that the SR-71 needed an aft-facing Electronic Countermeasures (ECM) system. Several Air Force feasibility studies looked at options such as conformal packages under the rear fuselage, belly pods, and an extended tail fairing. After evaluating all these concepts, the extended tail was judged the best solution, offering the lowest cost, additional internal space, and minimal aerodynamic drag. The resulting “Big Tail” structure measured 13 feet 9 inches in length, weighed 1,273 pounds, and provided 49 cubic feet of volume for up to 864 pounds of payload. Its primary payload would be aft-facing ECM equipment along with a 24-inch Optical Bar Camera. According to Habu.org, the longer tail section also had to be articulated so it could tilt 8.5 degrees upward for takeoff and landing to avoid runway contact, then rotate downward so it would not interfere with deployment of the aircraft’s drag chute during rollout.

The “Big Tail” made its first flight on Dec. 3, 1975. Testing showed that it caused only a minor reduction in performance, but the new sensor suite offered little real benefit. As a result, the program was canceled; this aircraft’s final flight took place on Oct. 29, 1976, and it remains the only “Big Tail” ever built.

Although Big Tail proved to be operationally effective, the Air Force decided not to develop the concept further. After just 36 flights with the enlarged tail section, #959 flew for the final time on Oct. 29, 1976. Today, SR-71A #61-7959 is on display at the Air Force Armament Museum at Eglin Air Force Base (AFB), Florida.

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Photo by U.S. Air Force and Air Force Armament Museum Foundation