Even though the USAF ordered 93 YF-12 aircraft and had an initial budget of $90 million for further testing, this was withheld by Sec. of Defense McNamara, who put it towards the F-106X program
The YF-12 Blackbird was created in the 1960s as a Mach 3, high-altitude interceptor designed to counter supersonic bombers. Built from the A-12 reconnaissance aircraft, the YF-12A became the predecessor to the advanced SR-71 strategic reconnaissance plane.
The first of the three YF-12 aircraft flew in August 1963. In May 1965, the first and third YF-12s established several records, including a speed of 2,070.101 mph and an altitude of 80,257.65 feet. For that speed record flight, Col. Robert L. “Fox” Stephens, the pilot, and Lt. Col. Daniel Andre, the fire control officer, were awarded the 1965 Thompson Trophy.
Unlike the A-12, the YF-12 carried no reconnaissance cameras. Instead, it was equipped with the Hughes AN/ASG-18 fire-control radar and could launch AIM-47 Falcon (GAR-9) air-to-air missiles.
The YF-12 program was canceled because of decisions made by Secretary of Defense Robert McNamara.
AIM-47 missile testing included six successful launches, while a seventh failed because of a gyro malfunction in one of the missiles.
The final missile was launched from a YF-12 flying at Mach 3.2 and 74,000 feet (23,000 m) toward a JQB-47E target drone only 500 feet (150 m) above the ground.
Although the missile carried no warhead, it struck the KQB-47E directly and removed a 4-foot section from its tail. The US Air Force regarded this as a success, but McNamara still chose to cancel the YF-12 program.
He ended the program because of its high cost, the ongoing war in Southeast Asia, and the reduced priority given to US air defense.
So, despite the USAF ordering 93 aircraft and allocating an initial $90 million for further testing, McNamara withheld that funding and redirected it to the F-106X program.
The F-106X was a design study for a follow-on to the Delta Dart. According to F-106 Delta Dart.com, once the XF-108 was effectively canceled, Convair tried to update the F-106 design. The concept called for a canard-configured interceptor powered by a JT4B-22 turbojet with rectangular air intakes. It was intended as an alternative to the Lockheed YF-12 and would have featured a fire-control system with “look-down, shoot-down” capability using a 40-inch radar dish.
The F-106X was considered highly advanced for its era, with Convair envisioning Mach 5 capability. Beyond the basic delta-wing shape carried over from the F-106, almost everything else would have been redesigned. A more powerful engine was planned, along with new intakes adapted for it. Canards were placed on the intakes, and the cockpit was raised to improve forward visibility. The fire-control systems were also supposed to be fully redesigned around the AN/ASG-18 previously developed for the XF-108.
“Under the F-106X development project were the designated F-106C/D aircraft, with “C” being the single-seat version, the “D” being the two-seat version.”
At one point, the USAF considered buying 350 of these advanced interceptors, and several efforts were made to upgrade the existing F-106 fleet, but none were approved by McNamara, and the F-106X program was canceled as well. McNamara later pushed the F-4 program instead.
He also ordered all YF-12 tooling to be destroyed. Notably, the tooling was more difficult to eliminate than expected because it was made of titanium. After the SR-71 Blackbird program ended, some tooling pieces were reportedly still found among the scrap after the aircraft were retired.
One journalist described McNamara as a “‘human IBM machine’ who cares more for computerized statistical logic than for human judgments.”
The YF-12 program officially ended in early 1968, and McNamara resigned as Secretary of Defense shortly afterward.
One YF-12 remained with NASA for testing until the early 1970s. An SR-71 was also at NASA disguised as a YF-12C. The last YF-12 can now be seen at the Museum of the US Air Force in Dayton, Ohio.
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Photo by U.S. Air Force and Convair
