U.S. Lockheed D-21 Supersonic Spying Drone Speed Mach 3.5

U.S. Lockheed D-21 Supersonic Spying Drone. Fifty years ago, on March 5, 1966, unmanned aircraft made supersonic history when a Lockheed D-21 drone launched off of the back of a Blackbird traveling Mach 3. The US always wanted speedster surveillance drones, and the Lockheed D-21 codenamed Project, “Tagboard”. First Supersonic UAV