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SR-71 "Blackbird"
An SR-71B trainer over the Sierra Nevada Mountains of California in 1994. The raised second cockpit is for the instructor.
Role	Strategic reconnaissance aircraft
National origin	United States
Manufacturer	Lockheed, Skunk Works division
Designer	Clarence "Kelly" Johnson
First flight	22 December 1964
Introduction	1966
Retired	1998 (USAF), 1999 (NASA)
Status	Retired
Primary users	United States Air Force NASA
Number built	32
Unit cost	$34 million
Developed from	Lockheed A-12

The Lockheed SR-71 "Blackbird" is a long-range, Mach 3+ strategic reconnaissance aircraft that was operated by the United States Air Force. It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by Lockheed and its Skunk Works division. American aerospace engineer Clarence "Kelly" Johnson was responsible for many of the design's innovative concepts. During aerial reconnaissance missions, the SR-71 operated at high speeds and altitudes to allow it to outrace threats. If a surface-to-air missile launch were detected, the standard evasive action was simply to accelerate and outfly the missile. The SR-71 was designed with a reduced radar cross-section.

The SR-71 served with the U.S. Air Force from 1964 to 1998. A total of 32 aircraft were built; 12 were lost in accidents, but none were lost to enemy action. The SR-71 has been given several nicknames, including "Blackbird" and "Habu". It has held the world record for the fastest air-breathing manned aircraft since 1976; this record was previously held by the related Lockheed YF-12.

Lockheed's previous reconnaissance aircraft was the relatively slow U-2, designed for the Central Intelligence Agency (CIA). In late 1957, the CIA approached the defense contractor Lockheed to build an undetectable spy plane. The project, named Archangel, was led by Kelly Johnson, head of Lockheed's Skunk Works unit in Burbank, California. The work on project Archangel began in the second quarter of 1958, with aim of flying higher and faster than the U-2. Of 11 successive designs drafted in a span of 10 months, "A-10" was the frontrunner. Despite this, however, its shape made it vulnerable to radar detection. After a meeting with the CIA in March 1959, the design was modified to have a 90% reduction in radar cross-section. The CIA approved a US$96 million contract for Skunk Works to build a dozen spy planes, named "A-12" on 11 February 1960. The 1960 downing of Francis Gary Powers's U-2 underscored its vulnerability and the need for faster reconnaissance aircraft such as the A-12.

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