The USAF ordered 93 production F-12B Blackbird Mach 3+ Interceptor aircraft, which would have been armed with three Hughes AIM-47A Falcon air-to-air missiles in enclosed bays in the bottom of the fuselage.
58 years ago!
Feb. 29, 1964: President Lyndon B. Johnson publicly revealed the existence of the Top Secret Lockheed YF-12A, a Mach 3+ interceptor designed and built by Clarence L. “Kelly” Johnson’s “Skunk Works.” President Johnson referred to the interceptor as the “A-11.”
The YF-12A interceptor is very similar to its A-12 Oxcart and SR-71A Blackbird stablemates. It is a large twin-engine delta wing aircraft, flown by a pilot and weapons system operator. Because of the altitudes that the F-12 operates, the crew wears S901F full-pressure suits produced by the David Clark Company.
After Johnson’s announcement the media wanted to see a YF 12… They went to Edwards Air Force Base to see it. The airplane was still hot since he had just arrived from Groom Lake, Area 51. Part of the reason why Johnson announced the YF 12 was to hide the CIA‘s A-12.

According to This Day in Aviation, the US Air Force (USAF) ordered 93 production F-12B* aircraft, which would have been armed with three Hughes AIM-47A Falcon air-to-air missiles in enclosed bays in the bottom of the fuselage. However, Secretary of Defense Robert S. McNamara refused to release the funds for the purchase for three consecutive years and eventually the project was cancelled. In fact, though the aircraft performed well, the F-12 interceptor program ended in early 1968. High costs, the ongoing war in Southeast Asia, and a lower priority on air defense of the US all contributed to the cancellation.
Variants:
- YF-12A Pre-production version. Three were built.
- F-12B* Production version of the YF-12A with various improvements such as an increased combat radius from 1,200 to 1,350 nautical miles and an improved fire control system with increased bomber detection range from 100 to 125 miles, canceled before production could begin.
- YF-12C Fictitious designation for an SR-71 provided to NASA for flight testing. The YF-12 designation was used to keep SR-71 information out of the public domain from 1971 to 1978, 61-7951 was temporarily loaned to NASA from the Air Force as “YF-12C #06937.”

The first of three YF-12s flew in August 1963. In May 1965, the first and third YF-12s set several records, including a speed record of 2,070.101 mph and an altitude record of 80,257.65 feet. For their speed record flight, Col. Robert L. “Fox” Stephens (pilot) and Lt. Col. Daniel Andre (fire control officer) received the 1965 Thompson Trophy.
The only remaining YF 12 is at the Museum of the Air Force near Dayton, Ohio.
Be sure to check out Linda Sheffield Miller (Col Richard (Butch) Sheffield’s daughter, Col. Sheffield was an SR-71 Reconnaissance Systems Officer) Facebook Page Habubrats for awesome Blackbird’s photos and stories.
Photo credit: U.S. Air Force
