Stealth and threat avoidance
The first operational aircraft designed around a stealthy shape and materials, the SR-71 had several features designed to reduce its radar signature. The SR-71 had a radar cross section (RCS) of around 10 square meters, much greater than the later Lockheed F-117 Nighthawk, which had an RCS equivalent in size to a ball bearing.Drawing on the first studies in radar stealth technology, which indicated that a shape with flattened, tapering sides would reflect most radar energy away from the radar beams' place of origin, engineers added chines and canted the vertical control surfaces inward. Special radar-absorbing materials were incorporated into sawtooth-shaped sections of the aircraft's skin. Cesium-based substances were added to the fuel to somewhat reduce the visibility of the exhaust plumes to radar, although the large and hot exhaust stream produced at speed remained quite apparent. For all this effort, Kelly Johnson later conceded that Soviet radar technology advanced faster than the stealth technology employed against it.
The SR-71 carried electronic countermeasures, but its greatest protection was its high speed and cruising altitude that made it almost invulnerable to the weapons of its day. Merely accelerating would typically be enough to evade a surface-to-air missile, and the plane was faster than the Soviet Union's principal interceptor, the MiG-25. In its service life, no SR-71 was shot down, despite many attempts to do so.
Few weapon systems have ever entered the military arena with such blinding superiority as did the Lockheed SR-71 Blackbird. No weapon system has ever maintained that same degree of superiority over a period of four decades. Today, the Blackbird is still the fastest, highest-flying, most-effective reconnaissance aircraft in history, even though budgetary considerations have caused it to be withdrawn from active service.
Like the U-2, a product of the U.S. government's super-secret Skunk Works research & development center, the Lockheed SR-71 Blackbird is a perfect expression of Kelly Johnson's genius and his leadership of a brilliant team of fewer than 200 engineers.
The USAF's SR-71 was a two-seat development of the earlier A-12 aircraft used by the Central Intelligence Agency. The Lockheed SR-71 Blackbird first flew on December 22, 1964, and by December 1967, all 31 of the Blackbirds had been delivered to the USAF.
The Blackbird was both a miracle of design and of production, for its performance (speed of Mach 3.2, more than 90,000 feet of altitude, a 4,000-mile range) had to overcome not only the sound barrier, but also the heat barrier. Skin temperatures of the craft exceeded 1,050 degrees Fahrenheit. Special fuels, hydraulic fluids, electronics, and glass had to be developed to match the strength of the aircraft's titanium structure.
A Lockheed SR-71 Blackbird, flown invariably by a highly skilled crew, became an invulnerable, invaluable reconnaissance aircraft. Unlike satellites in fixed orbits, the SR-71 could be deployed within hours to anywhere in the world.
The usefulness of the Lockheed SR-71 Blackbird went beyond military applications to diplomatic roles. During the 1973 Middle East Yom Kippur War, reconnaissance photos taken by the SR-71 determined the positions of the advancing Israeli forces, and were used during subsequent peace negotiations. And as a research instrument, the SR-71 has few peers; although officially retired, Blackbirds are rumored to be occasionally flown -- "unofficially" -- in NASA research.
Blackbirds set many records for speed and altitude, the last one a transcontinental speed record of less than 68 minutes -- on the delivery flight of a retired SR-71 to the National Air and Space Museum in Washington, D.C.
LOCKHEED SR-71 BLACKBIRD SPECIFICATIONS
Wingspan: 55 ft. 7 in.
Length: 107 ft. 5 in.
Height: 18 ft. 6 in.
Empty Weight: 60,000 lbs
Gross Weight: 170,000 lbs
Top Speed: Mach 3.2-plus
Service Ceiling: 90,000 ft.-plus
Range: 2,600 miles
Engine/Thrust: Two Pratt & Whitney J58 turbojets/32,500 lbs each
Crew: 2
Equipment: Wide range of classified intelligence-gathering equipment
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