By contrast, the manned SR-71 Blackbird, used for many years by the U. S. Air Force, had a top speed of just more than Mach 3.

相比之下，载人的SR - 71黑鸟，供美国空军使用多年，有一个仅比3马赫以上的速度。

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The SR-71 has proven its value as a complementary system to U.S. space-based reconnaissance assets during the prolonged period from 1985 to 1987 when the United States was unable to place new satellites in orbit.

CENTERFORSECURITYPOLICY: Center for Security Policy | Congress Must Preserve A Vital Strategic Reconnaissance Capability �� The SR-71