Lockheed YF-12

The Lockheed YF-12 is a prototype of interceptor Plane to high efficiencies designed by the the United States of America. It is one of the developments of the program Lockheed A-12 Oxcart launched by the CIA at the end of the years 1950, which led in particular to the famous spy plane SR-71 Blackbird.

In spite of good performances during in-flight tests, the YF-12 was never built in series: its only real use was the participation in a research program carried out by NASA until 1979.

Design

In September 1959, for budgetary reasons, the US Air Force gave up the project of XF-108 Rapier, an interceptor able to fly at Mach 3 and intended to replace the F-106 Delta Dart. Lockheed proposed then a derivative of the spy plane Lockheed A-12 Oxcart, by making the point that the essence of the design of A-12 was already carried out and thus that the plane would be less expensive. In October 1960, it was decided to take three planes on the assembly line of A-12 to transform them into prototypes YF-12.

The nose was modified to install the Radar Hughes AN/ASG-18 developed at the origin for the F-108 and of a range higher than 320 km. The size of the radome obliged to reduce the prolongations of the wings which were truncated compared to those of A-12. A second cockpit intended for the officer of shooting was added. The compartments containing the equipment of recognition of A-12 were modified to allow the carrying of 3 air-to-air missiles Hughes AIM-47A Falcon (them also initially intended for F-108) of 180 km range and being able to be equipped with a head with nuclear load. The modifications made to the aerodynamics of the plane obliged with the addition of Aileron S ventral under the fuselage and the nacelles of the engines to maintain stability.

The first of the three YF-12 made its inaugural flight on August 7th, 1963. The tests of larguage of missile, then of real shooting on remote-controlled targets, took place as from 1964: 6 of the 7 real shootings were successful, including a shooting since a flying YF-12 with Mach 3,2 and 23000 meters on a target flying definitely low. May 1st, 1965, a YF-12 established a simultaneous record speed and altitude by reaching 3330 km/h with 24462m.

Whereas USAF was ready to sign a contract of production for a hundred specimens, the Secrétaire with Defense refused to engage the funds and preferred to finance the F-106X (a F-106 Delta Dart with a new radar and other improvements which promised to be even less expensive… but does not lead of advantage). The project of F-12 was thus abandoned beginning 1968.

In 1969, two of the YF-12 were lent to NASA for a research program: exploration of the phenomena met in flight with high-speed (in particular thermal studies), studies aerodynamic, etc… The two planes carried out nearly 300 trial flights until 1979, closing date of the program. Last flight of a YF-12 take place on November 7th, 1979.

On the three built YF-12, was lost following a fire on board on June 24th, 1971, one is exposed to the museum of USAF and the last one was used to build single SR-71C (a two-seat trainer).

See too