The SR-71 was developed as a black project from the Lockheed A-12 reconnaissance aircraft during the 1960s by Lockheed’s Skunk Works division. American aerospace engineer Clarence “Kelly” Johnson was responsible for many of the aircraft’s innovative concepts. The shape of the SR-71 was based on that of the A-12, which was one of the first aircraft to be designed with a reduced radar cross-section.

At one point, a bomber variant of the aircraft was under consideration, before the program was focused solely on reconnaissance. SR-71 Blackbird: America’s Old Super Spyplane Is Still the World’s Fastest Jet.

SR-71 Blackbird: America’s Old Super Spyplane Is Still the World’s Fastest Jet