The new ‘Big Tail’ assembly would be 13 feet 9 inches long and weigh 1,273 lbs. with 49 cubic feet of space to carry 864 lbs. of payload. The primary payload would consist of aft-facing ECM as well as the 24-inch Optical Bar Camera
The SR-71, often called the “Blackbird,” is a long-range, highly advanced strategic spy plane that evolved from the Lockheed A-12 and YF-12A programs. Its first flight occurred on December 22, 1964, and the first operational SR-71 was assigned to the 4200th Strategic Reconnaissance Wing (later redesignated the 9th) at Beale Air Force Base in California in January 1966.
For almost 24 years in service, the SR-71 held the record as the fastest and highest-flying operational aircraft in the world. Flying at 80,000 feet, it was able to observe about 100,000 square miles of the Earth’s surface every hour. The US Air Force officially took the SR-71 out of service on January 26, 1990.
The striking photos in this post show a unique Blackbird, SR-71A #61-7959, nicknamed “Big Tail.”
Aircraft #959 was originally built just like any other SR-71 and rolled out on August 16, 1965. In 1975, however, it was selected to test a new suite of sensor systems housed in a nine-foot extension added to the rear of the aircraft.
When the SR-71 began flying operationally during the Vietnam War, some missions had to be scrubbed because of poor weather, which prompted experiments with an additional camera system.
There was also concern that, in the future, enemy air defenses might be able to target the SR-71 from behind, since the aircraft lacked rear-facing defensive countermeasures.
In 1974, the Air Force determined that the SR-71 needed rear-facing Electronic Countermeasures (ECM), and it reviewed several concepts, including conformal housings under the rear fuselage, belly pods, and an extended tail section. After evaluating these options, the extended tail was chosen as the best solution because it was the least expensive, offered more internal space, and created the least aerodynamic drag. The resulting “Big Tail” structure measured 13 feet 9 inches in length, weighed 1,273 pounds, and provided 49 cubic feet of space for up to 864 pounds of equipment. Its main payload was designed to include aft-facing ECM systems along with a 24-inch Optical Bar Camera.
According to Habu.org, the extended tail section had to be designed so it could pivot: it needed to angle upward by 8.5 degrees to avoid hitting the runway during takeoff and landing, and then rotate downward afterward so it would not block the drag chute when it deployed during rollout.
Additional changes included a 51-inch adapter section to attach the new tail, an air-conditioning system for the cameras and other onboard equipment, and rerouting the fuel vent along the top of the tail. Beyond the tail work, the chine bays were also altered so they could house the 24-inch Optical Bar Camera.
The “Big Tail” made its first flight on December 3, 1975. Testing showed that the aircraft’s performance was only slightly affected, but the new sensor systems offered minimal benefit. As a result, the program was canceled; this aircraft’s final flight was on October 29, 1976, and SR-71A #61-7959 remains the only “Big Tail” ever built.
Even though the Big Tail proved it could work in regular operations, the Air Force decided not to continue developing the idea. After just 36 flights with the extended tail, aircraft #959 flew for the last time on October 29, 1976. Today, SR-71A #61-7959 is on display at the Air Force Armament Museum at Eglin Air Force Base in Florida.
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Photo by U.S. Air Force and Rodney Miller via Linda Sheffield Miller
