The D-21 was intended to be carried near its target on the back of an M-21 mother ship. The M-21 was a development of the A-12, which was the forerunner of the SR-71 Blackbird.
The D-21 was intended to be carried near its target on the back of an M-21 mother ship. The M-21 was a development of the A-12, which was the forerunner of the SR-71 Blackbird.