Key point: In a tightly-knit industry with overlapping suppliers of hardware and spare parts, word got around — and traveling vendors were often a source of grist for the rumor mill.
There are few secret projects like U.S. Air Force black projects, and that was certainly the case for the famed SR-71 Blackbird.
The SR-71 was no ordinary aircraft but a big, beautiful and state-of-the-art spy plane designed in the 1950s and early 1960s to fly quickly at high altitudes over the Soviet Union, filling in for the U-2 Dragon Lady which had become vulnerable to then-new surface-to-air missiles.
Designer Lockheed and the Air Force treated the project with intense secrecy, and when still totally classified, the CIA recorded any hints that reporters, analysts or civilian plane watchers might have as to the jet’s existence. It didn’t matter who suspected it. If airport cab drivers were spreading rumors about secret doings at Lockheed, the agency wanted to know.
To keep the program under wraps, Lockheed engineers quietly worked on the plane at the company’s Skunk Works division in Burbank, California and the Air Force’s isolated Nevada base — known as Area 51 — beginning in 1958. The first Blackbird flew four years later.
The government surrounded the Blackbird with so much silence because it was an experimental plane and the first stealth aircraft, owing to its radar-reflective design. The SR-71's extreme performance — a speed of Mach 3.3 at an altitude of 85,000 feet — was highly sensitive information.
However, aviation experts and the press picked up on the project and did so relatively quickly, sometimes through sheer guesswork, according to the CIA’s recently declassified official history obtained by Governmentattic.org.