Lockheed California Company
ADP, Advanced Development Projects
D-21 Drone
1960s
The ramjet-powered D-21 was developed as a high-speed, unmanned strategic reconnaissance platform. Originally designed to be air-launched from atop specially-equipped A-12s (early SR-71s), designated M-21, they were later modified for underwing carriage and rocket-assisted launch by B-52 bombers.
Lockheed Photo