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The Lockheed YF-12 was a prototype interceptor Mach 3 +, based on project SR-71. Only three were built and only one remains today. The YF-12A program was canceled at the end of 60 due to financial reasons. However, the remaining aircraft remained in
800px-YF-12A left front view


service NASA until their final expulsion in 1979.


The SR-71 was the last in a series of aircraft that the famous Lockheed Skunk Works manufactured called the Blackbird Series (excluding the current stealth aircraft). There was the original A11, A12, YF-12A, M21, and the SR-71A,B and C. There was also a proposal to build a Blackbird Bomber (designated B12). Out of all of these aircraft the one that stands out is the Interceptor version of the Blackbirds called the YF12A.

Lockheed Skunk Works manufactured three YF12A Interceptor aircraft. The design is basically the same as the SR-71. However, modifications were made to the photo bays to accept the AIM-47 missiles; a cockpit was added to accommodate the Fire Control Officer; two ventral fins were added under each nacelle and a folding stabilizer fin was added under the centerline of the aircraft. The YF12A carried three GAR9/AIM-47 missiles which could carry a 250 kT nuclear warhead. The YF-12A nose is rounded to accommodate the Hughes ASG-18 Radar and Fire Control System. The ASG-18 was a combination of long range radar and infrared search sensors along with a precision radar coupled to the infrared tracking system. Range of the trackers was estimated at 200 to 300 miles giving the YF-12A unprecedented ability to track and destroy enemy aircraft.

During testing of the YF-12A, seven known missile firings occurred. These were conducted with the YF12A flying at Mach 2.0 or faster and the target drone aircraft flying at 40,000 feet or lower altitude.


The YF-12 Blackbird was fabricated of over 93% (structural weight) of titanium alloys to allow it to withstand skin temperatures of over 500 degrees Fahrenheit. It had the ability to carry three AIM-47A long range AAMs and could fly at mach 3 for substained periods.



Pre-production version. Three were built F-12B

Production version of the YF-12A, canceled before production could begin


Fictitious designation for a SR-71 provided to NASA for flight testing. The YF-12 designation to keep SR-71 information out of the public


General characteristics

  • Crew: 2
  • Length: 101 ft 8 in (30.97 m)
  • Wingspan: 55 ft 7 in (16.95 m)
  • Height: 18 ft 6 in (5.64 m)
  • Wing area: 1,795 ft² (167 m²)
  • Empty weight: 60,730 lb (27,604 kg)
  • Loaded weight: 140,000 lb (63,504 kg)
  • Max takeoff weight: 124,000 lb (56,200 kg)
  • Powerplant: 2× Pratt & Whitney J58/JTD11D-20A high-bypass-ratio turbojet with afterburner (turbo/ramjet hybrid)
    • Dry thrust: 20,500 lbf (91.2 kN) each
    • Thrust with afterburner: 31,500 lbf (140 kN) each


  • Maximum speed: Mach 3.35 (2,275 mph, 3,661 km/h) at 80,000 ft (24,400 m)
  • Range: 3,000 mi (4,800 km)
  • Service ceiling: 90,000 ft (27,400 m)


  • Missiles: 3× Hughes AIM-47A air-to-air missiles located internally in fuselage bays


  • Hughes AN/ASG-18 look-down/shoot-down fire control radar

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