Lockheed A-12: SR-71's precursor

The Lockheed SR-71 Blackbird is remembered as the fastest military aircraft ever produced, attaining top speeds of Mach 3 and holding the speed record for the fastest speed by a manned air-breathing plane (2,193 mph, achieved on July 28, 1976). However, most fans of the SR-71 Blackbird may not be aware that not all Blackbirds built were SR-71s, because the first iteration of the Blackbird to be constructed was the A-12. While visiting the California Science Center in July 2019 to mark the 50th anniversary of the Apollo 11 moon landing and the San Diego Air and Space Museum in August of that year, I had the chance to glance up two examples of the A-12, both of them mounted on pedestals outside their respective museums.

Top: A-11 design (left) and initial A-12 design (right) (after Robarge 2012) 

Bottom left: First A-12 (serial number 60-6924) on takeoff from Area 51 for its first official flight, April 30, 1962

Bottom right: A-12s lined up on the tarmac at Area 51, 1960s

For technical starters, at first glance, A-12 may look like a military designation, because the letter A in the US Defense Department's Tri-Service designation system for aircraft denotes attack aircraft. However, "A" in A-12 actually stood for Archangel, meaning that A-12 was the shortened form of Archangel-12. The Lockheed Skunk Works headed by Clarence "Kelly" Johnson had given the U-2 Dragon Lady the project codename Angel, and when CIA official Richard Bissell in 1957 asked US aerospace companies to look into designs for an advanced reconnaissance plane to replace the U-2, Lockheed chose to apply the project codename Archangel to design studies for a superfast U-2 successor, because those spyplane proposals were all intended to fly at altitudes above 90,000 feet at Mach 3, faster and higher than the U-2, which could only fly as fast as a subsonic jet bomber and early generation jet fighters. As aircraft designs evolved and changes to the configuration were made, the various Archangel studies became known as A-1, A-2, et cetera. By early 1959, Kelly Johnson unveiled two Archangel designs with diamond shaped delta wings, the A-10 with General Electric J93 turbojets and length of 109 feet, and the A-11 with two Pratt & Whitney J58 turbojets and a length of 116 feet (Robarge 2012, pp. 4-5). The A-11's rival design, the Convair FISH (First Invisible Super Hustler), had a much smaller radar cross section, and for this reason CIA official Edwin Lang rejected the A-11 design as not having a small enough radar cross section despite the immaturity of the technology planned for the FISH. Therefore, Johnson reworked the A-11 design with two J58s arranged in individual nacelles buried in the middle of the wings and twin canted fins to create the A-12. Lockheed submitted the A-12 design to a joint DoD-CIA-USAF panel at the Pentagon in July 1959, and Convair submitted their rival design, the Kingfish, with had two internally mounted J58s. Although the CIA favored the Kingfish because it had a much smaller RCS, the Convair company was facing cost overruns in development of the B-58 Hustler supersonic bomber, and because Lockheed had built the U-2 under budget and on time, the US Air Force persuaded the CIA to pick the A-12 instead, and on August 28, the A-12 was chosen as the successor to the U-2. The A-12 eventually was given the CIA codename Oxcart, and the CIA placed an order for twelve A-12s (serial numbers 60-6924/6939), the first of which flew on April 26, 1962 at Groom Lake, Nevada (flown by test pilot Lou Schalk. The A-12 fleet began deployment in May 1967 from Kadena Air Base in Okinawa, Japan, with operational overflights over North Vietnam. A number of A-12 sorties were conducted over North Korea, two of which took place when North Korea seized the warship USS Pueblo in early 1968. By now, budgetary constraints caused A-12 operations to be discontinued on May 1968, with the A-12s being retired in June. It would not be until 1982 that the CIA publicly disclosed details of the A-12 program.

Top: A-12 "Titanium Goose" (serial number 60-6927) preparing to refuel from a KC-135

Bottom left: Side view of the A-12 "Titanium Goose"; bottom right: Cockpit of the "Titanium Goose" in front view 

Now the overview of the A-12's development life brings my attention to the two above-mentioned examples of the A-12 that I have seen in person. The first one to be discussed, and the most jaw-dropping one, is the A-12 with the serial number 60-6927, which is on display at the Roy A. Anderson Blackbird Exhibit & Garden within the California Science Center. This aircraft, delivered in November 1963, was the only A-12 of its kind to be built in a two-seat trainer configuration, with the rear cockpit (accommodating the flight instructor) being raised and slightly offset relative to the front cockpit for the pilot. Instead of J58s, the A-12 trainer used the less powerful Pratt & Whitney J75 turbojets, and In case of an emergency, the flight instructor would take control of the aircraft. The appearance of the cockpit configuration led to 60-6927 being nicknamed "Titanium Goose" by the popular press. The "Titanium Goose" was transferred to the Military Aircraft Storage and Disposal Center in April 1977 years after being retired, and in August 2003 it was made an aviation exhibit at the California Science Center.

Lockheed A-12 serial number 60-6933 on display at the entrance to the San Diego Air and Space Museum in Balboa Park, San Diego, California. 

The other A-12 airframe that I saw during my travels that is worth discussing is the A-12 serial number 60-6933. This aircraft was the tenth A-12 to be built and delivered to Groom Lake, with delivery taking place in 1964. A number of traits are evident in this airframe that served to distinguish the A-12 from the later SR-71 Blackbird, including provisions for the pilot only, a slightly shorter fuselage, and the shape of the chines that were designed to deflect radar returns. Because the A-12 was intended to fly over enemy targets when penetrating enemy airspace, it could carry a better camera and far more spy instruments (the SR-71, by contrast, had SIGINT sensors and a side-looking airborne radar). Although the A-12 was made primarily from titanium to withstand heat friction at Mach 3, it also made use of radar-absorbent plastic composites on the edges of the wings to absorb radar waves. Ironically, even though individual airframes of most US military aircraft are consigned to the boneyards after retirement to be either scrapped or used for test purposes, all A-12s that were retired (five aircraft having been lost in accidents), including 60-6933 and 60-6927, made their way into museums.

Together with the SR-71, the A-12 represents the determination of the American aerospace industry to take spy plane technology to new heights during the Cold War by braving the technological challenges to developing a reconnaissance aircraft that could efficiently fly at high altitudes in the Mach 3 flight regime when flying over enemy territory. Due to the high value of the titanium alloy used in the A-12's construction, it is miracle that none of the A-12s retired from active duty were ever destroyed by the breaker's torch, and these planes will forever remain testaments to the ingenuity of Lockheed engineers in coming up with bold new ideas for future aircraft design.

References:

Landis, T.R., and Jenkins, D.R., 2005. Lockheed Blackbirds (Warbird Tech Series, Volume 10), Revised edition. Minneapolis, MN: Specialty Press. 

Robarge, D., 2012. Archangel: CIA's Supersonic A-12 Reconnaissance Aircraft, 2nd edition. Washington, D.C.: Central Intelligence Agency.