This week, the National Reconnaissance Office declassified a trove of documents pertaining to the long defunct “Tagboard” drone program, a reconnaissance effort so ahead of its time that it seemed like science fiction until only recently. In the 1960s, the United States found itself in a unique position: Nuclear programs in both China and the Soviet Union posed a clear threat to American security, and a number of burgeoning technologies promised to potentially lift the veil of secrecy created by the vast distances separating American experts from adversary programs.
After a U-2 spy plane piloted by Gary Powers was shot down over the Soviet Union in 1960, there was a growing emphasis on finding ways to get eyes on enemy programs without placing American pilots at risk. The A-12 “Oxcart,” predecessor to the legendary SR-71 Blackbird, promised to make photographic surveillance a less-risky venture, and early national reconnaissance satellites launched in 1960 offered more capabilities than ever before, but U.S. Department of Defense officials soon recognized that even the capabilities afforded by these two new technological marvels weren’t enough to keep America’s fingers on the pulse of the world’s nuclear developments.
“In view of the political sensitivity to overflight of certain denied areas, such as China, by manned collection systems and the technical and other limitations of the current satellite program, the Tagboard operational capability has been developed to collect against objectives of national interest located in areas where manned operations could provoke incidents potentially embarrassing to the United States,” a memo from the Joint Chiefs of Staff, penned in 1969, reads.
And thus, Lockheed’s D-21 Mach 3-capable drone was born. Built largely out of titanium and boasting a 19-foot wingspan, the D-21 was a 12-ton drone originally designed to ride atop the A-12. Once deployed, the D-21 could fly more than 3,000 miles, capturing a swath of territory 16 miles wide for the entirety of its flight before ejecting its 5,600-exposure film cartridge and self-destructing. From there, a specially equipped JC-130 would scoop the canister out of mid-air as it descended by parachute, or, failing that, a Navy ship could fish it out of the ocean.
But the program was hampered by disaster. On July 30, 1966, one of two A-12s that had been converted into D-21 drone carriers was conducting a test launch about 300 miles off the coast of California when the drone’s ramjet engine failed to fire. The drone slammed back down onto the fuselage of the A-12 while traveling in excess of Mach 3.2, ripping the fuselage away from the wings. As the fuselage tumbled helplessly downward, the pilot and engineer were able to eject, but the engineer ultimately drowned.
As a result, a decision was made to adjust the launch procedure for the D-21. Instead of carrying it to speeds in excess of Mach 3 for its ramjet motors to fire up, it was converted to use rocket boosters to carry it to the requisite speed after being fired from a much slower B-52 heavy payload bomber.
Within three years of the accident, the D-21 had been converted and was, as far as the National Reconnaissance Office was concerned, ready for action over China, where satellites had failed to provide sufficient coverage to shed any light on a number of high-priority targets tied to Chinese nuclear weapons programs. Radar-evading stealth had yet to be developed and the U.S. actually assumed that China would be able to spot and even track the fast-moving drone as it screamed across their skies, but the SA-2 air-defense missile systems employed by China at the time weren’t considered a threat at that speed or altitude.
Four total D-21 reconnaissance missions were launched over China in the following years and each effort was met with failure. On the third run, executed on March 4, 1971, the flight was successful but the parachute on the film canister failed to deploy properly, preventing the JC-130 from capturing it mid-air. Then, an issue attributed to “procedural errors” made a subsequent ship-based effort end in failure as well, with the film sinking into the ocean.
The program was ultimately shelved in favor of manned surveillance flights and increasingly capable satellite technology, but the NRO’s supersonic surveillance drone from the 1960s would go on to inform future unmanned efforts, and likely will for decades to come.