This M-21 is a unique variant of the A-12, the earliest Blackbird type. Built for a CIA program code-named "Tagboard," the M-21 carried unpiloted vehicles for intelligence gathering. These drones were intended for launch from the M-21 "mother ship" for flights over hostile territories. Design features of the M-21 include the second seat for the Launch Control Officer and the launch pylon on which the drone is mounted.
Fascinating photos reveal how they built the SR-71 Blackbird
Built and designed in the 1960s after the A-12 Oxcart, the SR-71 Blackbird is still the fastest, most vanguardist air-breathing airplane in the history of aviation. These once classified photos reveal how Lockheed built both birds in secret, in California. They look taken at the Rebel base in Hoth.