Lockheed YF-12

National Museum of USAF Lockheed YF-12

The Lockheed YF-12 was an American prototype interceptor aircraft, which the United States Air Force evaluated as a development of the CIA's highly-secret A-12 OXCART that also spawned the now-famous SR-71 Blackbird.

Design and development

The United States Air Force (USAF) YF-12 program was a development of the Lockheed A-12 OXCART spy plane designed for the CIA and first flown 26 April 1962, the first YF-12A flew on 7 August 1963. The existence of the aircraft was not officially revealed until 29 February 1964. Lockheed was able to interest the Air Force in the project after the United States Air Force had been forced to cancel the XF-108 Rapier, a Mach 3-capable interceptor intended to replace the F-106 Delta Dart in service. It was pointed out that an aircraft based on the A-12 would provide a less costly alternative to the XF-108, since much of the design and development work on the YF-12 had already been done and paid for. In 1960, the USAF agreed to take the 11th through 13th slots on the A-12 production line and have them completed in the YF-12A interceptor configuration.

The main changes involved modifying the aircraft's nose to accommodate the Hughes AN/ASG-18 fire-control radar originally developed for the XF-108, and the addition of a second cockpit for a crewmember to operate the fire control radar. The nose modifications changed the aircraft's aerodynamics enough to require ventral fins to be mounted under the fuselage and engine nacelles to maintain stability. Finally, bays previously used to house the A-12's reconnaissance equipment were converted to carry four Hughes AIM-47A (GAR-9) missiles.

SPECIFICATIONS:

Span: 55 ft. 7 in.
Length: 101 ft.
Height: 18 ft. 6 in.
Weight: 127,000 lbs. loaded
Armament: Three Hughes AIM-47A missiles
Engines: Two Pratt & Whitney J58s of 32,000 lbs. thrust each with afterburner
Crew: Two

PERFORMANCE:
Maximum speed: Mach 3+
Range: 2,000+ miles
Service ceiling: Above 80,000 ft.