A Blackbird at rest. “The M-21 is a variant of the A-12, the earliest Blackbird type. Built for a CIA program code-named “Tagboard,” the M-21 carried unpiloted drones for intelligence gathering. These D-21 drones were intended for launch from the M-21 “mother ship” for flights over especially hostile territory considered too “hot” for piloted Blackbird overflights. Unique design features of the M-21 compared to other Blackbird variants include the second seat for the launch control officer and the launch pylon on which the drone is mounted.
The Museum's M-21, built in 1963, and is the sole survivor of two M-21s constructed. The other one was lost in a drone-launching accident that led to the cancellation of the program.”