60-6940 was one of 2 airframes built from the ground up as M-21's, to be launch vehicles for the D-21 drone. The designations M-21 and D-21 come from reversing the numbers in A-12, and using M for "mothership" and D for "daughtership."
Built for a CIA program code-named "Tagboard" the M-21 carried unpiloted vehicles for intelligence gathering. Design features of the M-21 include the second seat for the Launch Control Officer and the launch pylon on which the drone is mounted.
When ferrying the D-21, the combination was called an M/D-21. The D-21 was powered by a Marquardt ramjet engine that had been developed and tested on the unmanned X-7 vehicle. Ramjets are essentially hollow tubes that use the compression of extremely fast air rushing into the inlet instead of a normal compressor/fan combination like a turbojet. As a result, the ramjet engine is useless below Mach 1.25.
The M-21 was a special A-12 designed to launch a D-21 drone, which would take over the reconnaissance mission without a pilot. Unlike most of today's recon drones, which are slow-flying glider-like machines, the D-21 was a ramjet-powered vehicle having performance similar to the SR-71.
The M/D-21 would take off and fly to speeds above Mach 3 and 80,000 feet. At this speed and altitude, the D-21B Drone's engine could be ignited and the drone launched from the back of the mothership, to fly along a preprogrammed course, then jettison its camera pack over neutral or friendly territory before self-destructing.
The surviving M-21, including D-21 drone, is displayed in Seattle's Museum of Flight.
2nd Model Choice: Lockheed SR-71A Blackbird
61-7950 was the first SR-71 produced; Lockheed test pilot Bob Gilliland flew her solo on her maiden flight on Tuesday, December 22, 1964.
61-7950 was lost on 10 January 1967 at Edwards AFB during an anti-skid braking system evaluation. The main landing gear tires blew out and the resulting fire in the magnesium wheels spread to the rest of the aircraft as it ran off the end of the runway. Lockheed test pilot Art Peterson survived, the RSO cockpit was unoccupied.
Unlike the A-12, the SR-71 went supersonic on its first flight, mostly because the J58 engines that were still being developed at the time of the A-12 s/n 924's maiden voyage had become available for the SR-71A.
About the SR-71"Blackbird"
The SR-71"Blackbird" is a long range, high-altitude, Mach 3+ strategic reconnaissance aircraft that was operated by the United States Air Force. It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by Lockheed and its Skunk Works division.
American aerospace engineer Clarence "Kelly" Johnson was responsible for many of the design's innovative concepts. During aerial reconnaissance missions, the SR-71 operated at high speeds and altitudes to allow it to outrace threats. If a surface-to-air missile launch were detected, the standard evasive action was simply to accelerate and outfly the missile. The shape of the SR-71 was based on the A-12 which was one of the first aircraft to be designed with a reduced radar cross-section.
The SR-71 served with the U.S. Air Force from 1964 to 1998. A total of 32 aircraft were built; 12 were lost in accidents with none lost to enemy action. The SR-71 has been given several nicknames, including "Blackbird" and "Habu".
About the Lockheed D-21B Drone
Gary Power's failed sortie over Soviet Russia in 1960 prompted military brass to search for unmanned alternatives for performing reconnaissance over hostile territory. The D-21 drone was Lockheed's solution/launched from a modified A-12, it spied on Red China at over 2,000 MPH.
Lockheed began its work in late 1962 on a high-altitude, high-speed reconnaissance drone. Originally dubbed the Q-21, the drone was built to travel at Mach 3.3 - 3.5 on the back of a Marquardt RJ-43 ramjet engine and to fly more than 3,000 nautical miles at an altitude of at least 87,000 feet. The drone was 43 feet long, six feet tall, and weighed 11,200 pounds with a 19-foot-wide double delta wing design over a titanium frame. It was also designed to travel just one way. The D-21 would carry a single high-resolution camera over a programmed flight path, then jettison the camera (which would parachute down for mid-air retrieval), and the drone itself would self-destruct. That's how it was supposed to work!
In all, the D-21 saw very limited action on the battlefield, making just four sorties over the People's Republic of China as part of Operation Senior Bowl while spying on the Lop Nor nuclear test site.
Citing the program's tepid results and a thawing of relations with China, Nixon cancelled the program in 1971 in favor of new-found spy satellite technology. The 38 drones produced during the program's run are now in various aviation museums around the world, and a couple are in Chinese museums near where they crashed.
Here's a few words about a Runaway D-21 Drone
Engineer Ben Rich worked on the D-21 program starting in 1962. Later, when he succeeded Clarence "Kelly" Johnson as the head of Lockheed's secret Skunk Works, he told of a day in the mid-1980s when a CIA man arrived carrying a panel.