From the 1960s until the 1990s the US spied on whoever it liked with impunity from the snapping cameras and greedy sensors of the fastest aeroplane ever to take off from a runway, the spectacular SR-71 Blackbird. We spoke to pilot BC Thomas about life in the most exciting seat in the world.
“Our maximum speed limit, directed by the Flight Manual, was Mach 3.3, but the SR-71 was not power-limited, so it could fly faster; however, doing so would exceed the compressor inlet temperature limit, as well as other limits both heat related and structural. I am certain that no pilot ever put both throttles in maximum afterburner and let the aircraft accelerate to see how fast it would go. That would be a violation of military orders, the flight manual restrictions, and common sense. I, and most probably all other pilots, never purposely violated any published limits while flying the SR-71.
The SR-71 could attain Mach 3.5, but the aircraft would be in an untested and prohibited area outside of its flight envelope, and serious damage to the aircraft might occur. The SR-71 was point-designed to cruise continuously at Mach 3.2, which is quite an achievement, but it was not intended to have a lot of margin above that speed.
I know of no time when the SR-71 was flown above Mach 3.33, and I doubt that one was flown faster, except by accidental error.”
What was best about flying it?
“The best aspect of being an SR-71 pilot was the mission, and I believe all who supported or flew the airplane operationally would agree. I was absolutely thrilled to be part of the strategic reconnaissance effort of the United States and by extension, the Free World, to survey our potential enemies and glean information that only we could provide, owing to our reconnaissance capability (sensors), and our stealth, flexibility, speed, and altitude. We advertised, that with 24-hour notification, we could be over any spot on earth, and capable to reveal what was there. That boast was successfully tested many times. And to a pilot who actively sought excitement paired with meaningful accomplishment, the notion of flying the fastest and highest-flying aircraft in the world while contributing to national security was unbeatable.”
….and the worst?
“The worst part of flying the SR-71 was the environment in which we flew. We flew fast and high, which complicated controllability and made over-controlling very dangerous because the SR-71 was delicate and not very manoeuvrable, as compared to other high-performance fighter aircraft. At Mach 3 and above, which were our usual cruising speeds, our acceleration limit was only 1.5 g, or 45 degrees of bank because of structural heating. We also operated in near- vacuum, where the air pressure was about 0.4 pounds-per-square-inch (psi), and if we were unprotected, our blood would boil and death would be instantaneous. To achieve enough dynamic air pressure to sustain lift, we had to fly fast, when air friction caused the average skin temperature of the aircraft to be 600 degrees F. The afterburner section was over 1,200 degrees F. We cruised at 15 miles above the earth so any cockpit environmental problem, such as high temperature, low pressure, or oxygen depletion, could be fatal, because slowing down and descending could not be achieved quickly.”
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