Following the thread...I was in Palmdale, California for the 2006 show at Edwards AFB.

From a sign posted at the Palmdale, California exhibit:

"The D-21 was an unmanned, ramjet-powered craft designed to be air-launched from atop
an A-12 (redesignated M-21) mother ship. It was conceived as a reconnaissance
platform that would fly over high-threat targets without endangering a pilot. After
acquiring photos of its target, the D-21 would return to a safe area and eject a
hatch containing the reconnaissance equipment. As the hatch was lowered by
parachute, it would be recovered in mid-air by a JC-130B Hercules. The project was
terminated after a fatal accident on the fourth test launch. Four operational
missions were later flown from B-52 launch aircraft. This D-21 is on loan from NASA."

Tom

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