The United States Department of Defense has spent decades toying with the idea of unmanned aircraft. In the 1960s, they used supersonic, high-flying drones to fly missions over China.

Need For Drones

It was May of 1960, and CIA pilot Francis Gary Powers was shot down over the Soviet Union while flying the classified U-2 Spy Plane. Of course, the downed plane became the source of an international incident.

President Dwight Eisenhower decided there would be no more manned flights in the Soviet Union's airspace. But that left the United States with a gap in surveillance since satellites were under development.

Lockheed took the problem head-on. Kelly Johnson, the engineer behind the U-2 Spy Plane and the SR-71 Blackbird, began working on a design in October 1962.

The drone named the D-21 used a lot of the technology that was meant for the A-12. The CIA and U.S. Air Force's requirements were lengthy.

They wanted it to reach Mach 3.3-3.5, hit an altitude of 87,000- 95,000 feet, and a fuel range of 3,000 nautical miles. The project would be considered a Herculean feat even for current engineers, but Johnson was convinced he could manage.

Testing The D-21

He met all the requirements but used a ramjet engine to make it work. The engine only functions at high altitudes, so it had to be dropped from a plane. In this case, it was the M-21 Blackbird.

The drone was 43 feet long, and the wings measured 19 feet and looked similar to the A-12. It had a high-resolution camera that took photos while it flew. The photo canisters would be ejected from the drone and floated down to the water. Navy ships would catch them as they came down but would grab them from the water as needed.

If the drone itself was captured, it could self-destruct. Three test flights went well, but the fourth try failed. The drone and the M-21 crashed into one another at Mach 3.25.

The pilots ejected, but before they could be rescued, one of them drowned. After the incident, they moved to deploy the D-21 from a B-52H bomber.

Four drones were launched into Chinese airspace, with two completing their mission. However, one did not eject its film, and the other was irretrievable. The other two were presumed to have been shot down. On July 15, 1971, the program was canceled.