The SR-71 was built in the late Fifties, it was kept a secret until the mid 70's. Much of the information about the SR-71 is still classifyed today even after its retirement in the early 90's.
In the words of Kelly Johnson, "It makes no sense to just take this one or two steps ahead, because we'd be buying only a couple of years before the Russians would be able to nail us again. No, I want us to come up with an airplane that can rule the skies for a decade or more." He wanted to design an airplane that used conventional engines and fuel, but still be able to outrace any missile.
The Blackbird, code-named Oxcart during its development, flies on a tremendous 65,000 lbs. of thrust at an altitude of 100,000+ feet at Mach 3.5, and has a range of four thousand miles.That is not only four times faster than the U-2 but seven miles higher - and the U-2 was then the current high-altitude champion. For a long time the Air Force claimed a maximum speed of Mach 3.2 and an operational ceiling of 85,000 feet, but we now know that the SR-71 can soar above 100,000 feet. Compared to the fastest jet fighter America had at the time, the SR-71 flew at least 60 percent faster than its maximum speed on afterburner. Experimental rocket engines had flown this fast for only two or three minutes at a time before running out of fuel. But the Blackbird can cruise at more than three times the speed of sound, and fly coast to coast in less than an hour on one tank of gas. The aircraft can also survey more than 100,000 square miles of the Earth's surface in one hour. The Blackbird actually stretches a few inches during flight, due to the massive temperatures on its titanium hull. The Blackbird is the epitome of grace and power, not to mention blinding speed.Tecnical data:
The Lockheed SR-71 was sent into retirement in 1990. It it supposed that it will be (or has been) replaced by the secret Aurora aircraft. Rumor has it that the Aurora was developed to replace the SR-71 aircraft. It is supposed to be able to fly at Mach 6. It's sonic booms have been recorded in the Nevada desert, and it has been sighted off an oil platform in the North Sea. However, no one is certain that it really exists.