High Quality Content by WIKIPEDIA articles! The Lockheed D-21 was an American Mach 3+ reconnaissance drone. The D-21 was initially designed to be launched from the back of its M-21 carrier aircraft, a variant of the Lockheed A-12 aircraft. Development began in October 1962. Originally known by the Lockheed designation Q-12, the drone was intended for reconnaissance missions deep in enemy airspace.