What's amazing to me about the SR71 is that it was designed with slide rulers.
in 1957, no less!!! At least, its original sketches were done then.
BINGO!
The Blackbird has been my favorite aircraft of all time, and I even have pictures of some of them dating back to the early 70s taken by a brother of mine who was in the Air Force at the time.
The actual beginning of this project dates back to 1956 with the CIAs request for "a jet that could fly at extremely high speeds and altitudes while incorporating state-of-the-art techniques in radar absorption or deflection". It was codenamed GUSTO.
In 1957, the U-2 Project Manager set up an advisory committee to select the design which had a whole buncha top-dog bigwigs in it.
It was Lockheed's chief engineer Kelly Johnson who said "“It makes no sense to just take this one or two steps ahead, because we’d be buying only a couple of years before the Russians would be able to nail us again….I want us to come up with an airplane that can rule the skies for a decade or more."
And on April 21, 1958 they commenced the design work on an aircraft that would cruise at Mach 3.0 at altitudes above 90,000 feet. The design concept was submitted to the committee July 23, 1958, three months later.
The project was codenamed "Archangel" and progressed through several iterations from Archangel-1, Archangel-2, etc. (The numbers starting to sound familiar?)
In March 1959, Lockheed developed a design for the A-11. It would have a top speed of Mach 3.2, a range of 3,200 miles, and an altitude of 90,000 feet, and could be ready by January 1961.
This went through further design evolutions to become the A-12, in the curvy configuration we know of today. August 29, 1959, it was selected by the committee. BUT Lockheed had 4 months to prove the design would reduce the radar cross section significantly.
Construction actually began in September of 1960.
God, I love this aircraft!
Here's a really cool read on the history:
https://www.cia.gov/library/center-...nographs/a-12/Archangel-2ndEdition-2Feb12.pdf