By 1962, Kelly Johnson had done at least a few studies on using the A-12 as a carrier for a QF-104 Starfighter
The A-12 was the result of the military’s secret Project Oxcart, which aimed to create a high-altitude, high-speed reconnaissance aircraft. The A-12 was built by Lockheed’s Advanced Development Projects office, currently known as Skunk Works, and had its maiden flight in 1962. The A-12 could reach speeds above Mach 3, or three times the speed of sound, while conducting sensitive intelligence-gathering missions. Up until 1968, the A-12 was employed by the Central Intelligence Agency (CIA) for surveillance missions. Through the 1990s, later models dubbed the SR-71 Blackbird, were used by NASA and the US Air Force (USAF) for test and reconnaissance missions.
In the book Origins and Evolution Lockheed SR-71 Blackbird, Scott Lowther says that two of the A-12 airframes were initially constructed for an entirely different purpose. As the program was developed, the CIA was worried about the dangers of flying a manned vehicle over enemy territory, especially one as advanced as the A-12. As the shootdown of Francis Gary Powers plainly illustrated, the loss of a pilot and advanced technology over “denied” territory may prove to be both politically embarrassing and technologically devastating. As a backup, they asked Kelly Johnson and his group to research unmanned drones that could be launched from the back of the A-12.
Johnson had conducted at least a few studies on the A-12’s potential use as a carrier for a QF-104 by 1962. There is little more to go on than the simple description of the idea; therefore, it’s unclear how different the QF-104 would have been from the standard F-104. This diagram should be regarded as completely provisional.
On the other hand, the concept appears feasible enough initially. However, using a more or less stock F-104, which can reach a ceiling of 50,000 feet and a speed of around Mach 2, from an aircraft that can travel more than 50% faster and higher would be unusual. It is also probable that a ramjet, with modified aerodynamics and structure to allow for higher speeds and altitudes, would have taken the place of the J-79 turbojet.
It appears that the CIA was more interested in the AQ-12, a brand-new, highly optimized drone, rather than in the A-12/QF-104 concept. Under the program, the AQ-12 would be launched from the back of an A-12 designated “M-21,” where M stands for “Mother” and 21 is just the 12 reversed to avoid misunderstanding. The AQ-12 was renamed D-21, where D stands for “Daughter.”
During the fourth flight test, the mothership pitched up and collided with the D-21 at Mach 3.25 as a result of an “asymmetric unstart” that occurred as the D-21 went through the M-21’s bow wake. Ray Torick and Bill Park, two of the crew, were ejected from the M-21, but Torick drowned after his flight suit tore and filled with water.
The M-21 launch program was halted following the mishap. Under the secret Tagboard test program, testers still believed the D-21 would make a valuable reconnaissance vehicle and chose to launch the drone from B-52Hs. Senior Bowl was the new code name assigned to the D-21 project.
D-21s were used on four missions over communist China under Senior Bowl, although none of these missions was a complete success. In 1971, the USAF terminated the program and put in storage the remaining D-21 aircraft.
Origins and Evolution Lockheed SR-71 Blackbird is published by Mortons Books and is available to order here.
Photo by U.S. Air Force and Scott Lowther via Mortons Books