Turns out there’s a reddit thread on the exact question of the S-200 vs. the: SR-71. Copying in the top comments so people don’t have to click through:
Why the soviet union didnt use the S-200 aginst the SR-71 blackbirds?
Because the US discontinued overflights of the USSR after the shootdown of Gary Powers’ U-2 in 1960.
As to why other adversaries with SA-5s didn’t...well, Libya tried. The SR-71 isn’t as stealthily as a B-2, but they were stealthy enough to reduce the acquisition range considerably. Combined with a closure rate of Mach 3.3, the SA-5 crews had very little time to acquire, track, and fire. And when the target is somewhere smaller than the USSR, they can be in and out of enemy airspace in minutes. The SR-71 also had a robust ECM capability to jam the incoming missile.
And if that failed they could outmaneuver the missile. With the Blackbird traveling at a mile every couple of seconds, the missile is computing a lead of several miles at launch. While the SR-71 wasn’t aerobatic, missiles at Mach 6 are worse. Even if they couldn’t get out of the missile’s radar arc, they could get it to overshoot.
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They may have. But the Blackbird still could have outsped the S-200. It wasn’t that the Blackbird was faster than the missile. It was that it could fly just fast enough that even a faster missile could not catch up. Try and imagine the whole scenario. A Blackbird is zooming in, high and fast. It gets detected. That detection gets evaluated, passed on, until the decision is reached to launch an S-200 missile. All of that might take minutes, and the plane travels at about 80 km every minute. Now, the launch site is stationary and at ground level. The missile has to ignite, accelerate, climb, and adjust course (presumably, the SR-71 would not fly just over the launch site). All while the missile is doing all of that, the plane is speeding away (and presumably accelerating as the pilot becomes aware of the missile). When the missile gets to altitude, it would be able to catch the plane eventually, but it probably will run out of fuel.
Turns out there’s a reddit thread on the exact question of the S-200 vs. the: SR-71. Copying in the top comments so people don’t have to click through:
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https://www.reddit.com/r/WarCollege/comments/rb7stm/why_the_soviet_union_didnt_use_the_s200_aginst/