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The OXCART "Family"
The A-12’s unique design and
characteristics became the foundation for three other versions of supersonic
aircraft that Lockheed built for CIA and the Air Force: the YF-12A, the M-21,
and the SR-71.
KEDLOCK:The YF-12A
In October 1962, the Air
Force ordered three interceptor variants to replace the cancelled F-108A
Rapier. The modified A-12, first designated the AF-12 and then the YF-12A, was
designed and built under a project codenamed KEDLOCK. The aircraft’s mission
was to intercept new Soviet supersonic bombers long before they reached the
United States. It carried three air-to-air missiles and a second crewman who
worked the fire control system. The Air Force initially envisioned a fleet of
as many as 100, but only three were built and delivered during 1963-64.
Secretary of Defense Robert McNamara cancelled KEDLOCK in early 1968 as a
cost-cutting measure, and the aircraft were never deployed operationally. CIA
was involved with the project only in giving up three A‑12 airframes and
helping write “black” contracts. The Air Force bore all the costs of the
YF-12A, which was superseded by the F-111. Two of the aircraft were given to
the National Aeronautics and Space Administration for research, and one was
converted into a trainer for the SR-71 program.
TAGBOARD: The M-21 and D-21
In October 1962, CIA
authorized the Skunk Works to study the feasibility of modifying the A-12 to
carry and deploy a reconnaissance drone for unmanned overflight of denied
areas. The project was codenamed TAGBOARD. The mother ship, redesignated the
M-21 to avoid confusion with the A-12, was fitted with a second seat for a
launch control officer (LCO) for the drone, called the D‑21. It was 43 feet
long, weighed over five tons, had a ramjet engine, could reach a speed of over
Mach 3.3 at 90,000 feet, fly over 3,000 miles, and had the smallest RCS of
anything Lockheed had yet designed. The drones would be launched well away from
targets, fly their missions, and return to a preprogrammed location in
international waters. There they would jettison a payload that a C-130 would
snag in midair, and then self-destruct with a barometrically activated
explosive device. In June 1963, the Air Force took over the project because it
had overall charge of unmanned reconnaissance aircraft. Lockheed eventually
built two M-21s and 38 drones, and its test pilot Bill Park flew all the M-21
flights. On the fourth TAGBOARD test on 30 July 1966, a launch mishap caused
the mother ship to crash, killing LCO Ray Torick and prompting Kelly Johnson to
end the program. Afterward the Air Force used B-52s to launch the drones
against Communist Chinese targets in a project called SENIOR BOWL. Four
missions were flown starting in November 1969. None was completely successful,
and SENIOR BOWL was cancelled in July 1971.
SR-71 Blackbird
The best known version of the
A-12 (above right) is the SR‑71 Blackbird (above left), whose nickname has
become eponymous with the entire set of OXCART variants. In December 1962, the Air Force ordered six
“reconnaissance/strike” aircraft for high-speed, high-altitude flights over
hostile territory after a nuclear attack—hence its original designator RS.
Compared to the A-12, the SR-71 was about six feet longer, weighed 15,000
pounds more fully loaded, had more prominent nose and body chines and a
two-seat cockpit, and carried additional optical and radar imagery systems and
ELINT sensors in interchangeable noses.
With the added weight, the
aircraft flew slower and lower than the A-12 or the YF-12A, but it carried more
fuel and had a longer range. After an initial contract for six RS-71s, the Air
Force ordered 25 more in August 1963. When President Johnson disclosed the
aircraft’s existence in July 1964, he mistakenly transposed the designator
letters. Air Force officials let the error stand and came up with the Strategic
Reconnaissance (SR) category instead. The fleet, based in the United Kingdom,
Okinawa, and California, flew over
3,500 sorties from March 1968 until November 1989, when it was deactivated. In
September 1994 Congress allocated funds to reactivate three SR-71s. Two
aircraft and crews became operational during 1995 and 1996. In October 1997,
President Bill Clinton vetoed further funding, and in June 1999 the SR‑71
program was shut down again.
Historical Document
Posted: Oct 01, 2007 08:35 AM
Last Updated: Jun 27, 2008 09:55 AM
Last Reviewed: Oct 01, 2007 08:35 AM