In 1956, the U.S. Air Force had a big problem. The high-flying, camera-equipped U-2 spy plane had flown for the first time just a year earlier. But as America’s main strategic reconnaissance aircraft, the subsonic U-2 was already obsolete.
The Air Force’s solution was to develop a new spy plane. The resulting Blackbird more than matched the U-2’s impressive high-altitude performance and added the ability to fly at three times the speed of sound.
In 35 years of military and CIA service, the Blackbird became legendary for its blistering top speed and sinister appearance. But a just-released, formerly top-secret official CIA history underscores the Blackbird’s lesser-known but equally important accomplishment.
In addition to being really, really fast, the Blackbird was also the world’s first operational stealth warplane—an honorific that most historians reserve for the 1980s-vintage F-117.
In the mid-1950s, America’s first spy satellites were still in development. The only way for the Pentagon to spot the Soviet Union’s army divisions, airfields, and command centers was to fly an airplane overhead and snap photographs.
The U-2 was supposed to revolutionize aerial reconnaissance. And in way, it did. Upgraded with new sensors and engines, the U-2 is still the Air Force’s most important spy plane, 61 years after its first flight.
But with big, straight wings that readily bounced back radar signals, the U-2 proved highly vulnerable to Soviet air defenses. “The U-2 was not only detected by radar as it penetrated denied territory, but was tracked quite accurately in its earliest flights over… Soviet areas,” the CIA noted in an official history the agency completed in 1969.
The document was released through a Mandatory Declassification Review and the once-top-secret history was posted by Governmentattic.org.
With a top speed of just 500 miles per hour, the U-2 was too slow to outrun supersonic surface-to-air missiles. In 1960, a missile blew Gary Powers’s U-2 out of the sky over the Soviet Union, sparking a diplomatic crisis.
The Pentagon wanted its next spy plane to sneak right past Soviet radars. As luck would have it, Edward Purcell at Harvard University had just invented a new material that could absorb radar energy. “His discovery led to laboratory work in techniques to blanket portions of the aircraft radar-absorptive materials in order to reduce radar detection,” the CIA noted.
The Air Force added the new material to a few U-2s, but that made the planes too heavy. The flying branch went back to the drawing board. “Focus turned to the feasibility of a reconnaissance aircraft designed to greatly reduce radar cross-section specifications as the primary objective.” The Air Force gave the new spy-plane project the code name Gusto. Plane-makers Lockheed and Convair developed competing designs.
While Convair’s design team veered off to a dead-end effort to develop a small, Mach-4 plane that launched in mid-flight from a bomber “mothership,” Lockheed’s own team plugged away at a slightly more conventional aircraft for the Gusto requirement.
Lockheed’s A-12—that was the CIA’s version of the Blackbird—took off for the first time in April 1962 and, together with the Air Force’s follow-on SR-71 version of the plane—ushered in a new era of espionage. Made largely of titanium and built around two immensely powerful J58 engines, the Blackbird could fly as high as 85,000 feet at a top speed of Mach 3.3 while lugging up to a ton and a half of sophisticated sensors.
The Blackbird’s stealth qualities took shape at a secret base in Nevada that would come to be known as Area 51. A small team of engineers tweaked and tested the spy plane’s radar-reflectivity, pursuing the two main principles of stealthiness—materials and shaping.
“The airframe areas giving the greatest radar return were the vertical tail, the inlet and the forward side of the engine nacelles,” the CIA noted. “An improvement in the chine [the side edge of the plane’s fuselage] and wing regions was also being looked at.” The engineers experimented with new ceramic materials with high degrees of magnetic permeability and low conductivity, meaning they can suck up electromagnetic energy such as radar.
“It was hoped that a significant reduction in radar return could be accomplished,” the CIA explained. In May 1967, the intelligence agency finally put the Blackbird to the stealth test. A detachment of the speedy planes deployed to an Air Force base in Japan for 58 spy flights over North Vietnam and neighboring countries as part of Operation Black Shield.
The results were… disappointing. The Blackbird was a stealth jet. But it wasn’t as stealthy as the military and CIA had hoped it would be. “Enemy radar tracking was reported on all but four missions,” the agency admitted. Communist forces launched eight surface-to-air missiles at the Blackbirds. Seven missed. One exploding missile apparently managed to nick a Blackbird with a small metal fragment.
“The [radar] cross-section levels that the designers achieved were, in fact, quite low,” the CIA explained. “However, the advances the Soviets were making in their radar defense network were equally impressive.”
Washington banned Blackbirds from flying directly over hostile territory unless they were assisted by electronic radar-jamming. But that doesn’t mean the Blackbird failed as a stealth plane.
Indeed, the Mach-3 spy jet helped the Air Force and CIA to appreciate an important truth. Stealth alone can’t protect any plane. “There is no silver bullet,” Col. Alex Grynkewich, the Air Force officer heading the flying branch’s concept-development for its next stealth fighter, said… in 2016.
Which is why today’s F-22 and F-35 stealth fighters are also heavily armed and supersonic. And why the Air Force’s current B-2 stealth bombers usually attack their targets in concert with other warplanes, cruise missiles, and plenty of electronic jamming.
“All possible means of reducing vehicle vulnerability [must] be exploited,” the CIA asserted in its 1969 history. Sixty years ago, that meant making the Blackbird not only the world’s fastest spy plane, but also the world’s first stealth plane.