Even more Top Secret than the Lockheed SR-71, the D-21 drone was a promising Cold War idea that could have eliminated the need for manned overflights, although it was mostly unsuccessful. After the ...
Lockheed developed a spy drone in the 1960s that crashed in China. China recently debuted a supersonic drone that bears a striking resemblance to Lockheed's D-21. The D-21's urgent development was ...
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