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Designed in the Skunk Works<\/h2>\r\n\r\n\r\n\r\n
The SR-71 was the product of Lockheed’s Advanced Development Projects division \u2014 universally known as the Skunk Works, after a moonshine operation in the Li’l Abner comic strip. Led by Clarence “Kelly” Johnson, one of the most gifted aircraft designers in history, the Skunk Works operated with minimal bureaucracy and maximum talent. Johnson’s design philosophy was direct: “Be quick, be quiet, be on time.” The SR-71’s predecessor, the U-2, had been designed and built in eight months.<\/p>\r\n\r\n\r\n\r\n
The A-12, the SR-71’s direct ancestor, was designed starting in 1957 to replace the U-2 \u2014 which, as events in 1960 would prove, was vulnerable to Soviet surface-to-air missiles. The solution Johnson chose was brutal in its simplicity: fly so high and so fast that no missile could reach you. The resulting aircraft was a masterpiece of engineering necessity. Flying at Mach 3.2+, aerodynamic friction heats the airframe to temperatures that melt aluminium. Johnson chose titanium \u2014 stronger, lighter, and capable of withstanding the heat. The problem was that the United States produced almost no titanium domestically. The main global source was the Soviet Union. The CIA secretly purchased Soviet titanium, routed through shell companies, to build an aircraft designed to spy on Soviet military installations.<\/p>\r\n\r\n\r\n\n
\n\u201cWe had to build everything ourselves. There were no manufacturers with the right materials, the right machines, or the right experience. The SR-71 taught the industry how to work with titanium.\u201d\n<\/p>\n\u2014 Ben Rich, Skunk Works engineer and Kelly Johnson’s successor<\/cite>\n<\/div>\n\r\n\r\n\r\n At cruising speed, the SR-71’s airframe reached 316\u00b0C at the nose cone and around 260\u00b0C across the wing surfaces. The cockpit windscreen got hot enough to fry an egg. The titanium skin expanded several inches in length during a high-speed run. The aircraft was designed with gaps between panels \u2014 it literally leaked fuel on the ground, the gaps being intended to seal when the metal expanded at temperature. Ground crews joked that the SR-71 only stopped leaking when it was flying fast enough to need the fuel.<\/p>\r\n\r\n\r\n\r\n The engines \u2014 two Pratt & Whitney J58 turbojets \u2014 produced 32,500 pounds of thrust each. At Mach 3.2, the inlet compression heated the intake air to around 427\u00b0C before it even reached the engine. The J58 was designed to operate partly as a ramjet at high speed, bypassing the compressor stages and running on the ram pressure of the incoming air. It was the most sophisticated operational aircraft engine ever built.<\/p>\r\n\r\n\r\n\r\n The SR-71 entered service with the US Air Force in 1966 and flew operational missions until 1989, when it was retired \u2014 controversially \u2014 for budget reasons, replaced by satellite reconnaissance systems that the Air Force argued could do the same job at lower cost. The aircraft was briefly recalled to service in 1995 when it became clear that satellites couldn’t provide the rapid-response reconnaissance capability the SR-71 offered, then permanently retired in 1998.<\/p>\r\n\r\n\r\n\r\n In those 24 years, SR-71s flew over North Vietnam, North Korea, Libya, the Middle East, Cuba, and the Soviet periphery. They photographed missile sites, naval bases, troop concentrations, and anything else the intelligence community wanted to see. They flew during the Yom Kippur War, the Falklands War, the Gulf War. Over 4,000 missiles were fired at SR-71s during the Cold War. None found their target. The standard procedure remained the same throughout: when a launch was detected, the pilot pushed the throttles forward and the world fell away behind him.<\/p>\r\n\r\n\r\n\r\n The absolute speed record \u2014 Mach 3.3, 2,193 mph, set on July 28, 1976 \u2014 still stands. Nothing with a conventional engine has matched it. The SR-71 remains, in that specific and remarkable sense, undefeated. It holds the record not because no one has tried to beat it, but because no one has found a reason compelling enough to justify the engineering required. For a machine that was designed in the 1950s and flew for the last time in 1998, that is an extraordinary legacy.<\/p>\r\n\r\n\r\n\nThe Physics of Flying at Mach 3<\/h2>\r\n\r\n\r\n\r\n
24 Years, 3,500 Missions, Zero Losses<\/h2>\r\n\r\n\r\n\r\n