3 ms·

It's more complex than this though. At those speeds there is no margin for error for the intercepting aircraft and missile. There are lots of accounts from S

It's more complex than this though. At those speeds there is no margin for error for the intercepting aircraft and missile. There are lots of accounts from SR-71 pilots about this. At Mach 3 slight changes in course result in large changes in position very quickly. Mach 3 at SR-71 altitudes is > 30 miles per minute. The pilots could make course changes that would put the plane off the original intercept by miles within seconds and it was very hard for a missile to adjust for that, missiles run out of fuel very quickly and have to burn their energy to change course. And they weren't very smart in the cold war. The Soviets never managed to intercept an SR-71 even to scare it off by most accounts. The Swedes apparently claimed to have done it but only because they were friendlies and the SR-71 wasn't changing course to evade them.

netjiro 5y ago
The Swedes also "almost" developed a small fast business jet from a military airplane. The SAAB 105 "SK 60" military trainer had a development branch for a five seat civilian model [1]. I recall hearing it got cut sometime around the oil crisis back then. It is a quite good plane, and surprisingly silent. [1] https://en.wikipedia.org/wiki/Saab_105 https://en.wikipedia.org/wiki/Saab_105
sudosysgen 5y ago
There is ample margin of error. You forget that both airplanes are going at Mach 3+. The SR-71 might be going at Mach 3.4 and the MiG-25 at Mach 3.2, and this difference in speed is not anywhere near sufficient to prevent the interceptor from compensating. >The pilots could make course changes that would put the plane off the original intercept by miles within seconds and it was very hard for a missile to adjust for that, missiles run out of fuel very quickly and have to burn their energy to change course. And they weren't very smart in the cold war. No, that's not true. By the time the missile is fired, at a distance of, say, 30km, the SR-71 has anywhere between 10 seconds and 2 minutes before being hit. From the SR-71 flight manual, we can find a turning radius of 105 nautical miles at Mach 3.2, and extrapolate to 140 nm at Mach 3.4. That means a 259km turn radius, and a 1700km turning circumference, meaning that every degree of rotation translates to, at 1180m/s, 4 entire seconds So, the missile would have a very easy job. At a turn rate of 1 degree every 4 seconds, even in pure pursuit ("not very smart"), the missile would not have to expend much energy at all.
- fakethenews2022 5y ago
  What I read is that the final Soviet tactic was to “surround” the SR-71 with MIG-25s so that it had nowhere to turn. I suspect that getting to within 30km of the SR-71 would not have been easy for a single MIG. The MIGs would have had to accelerate to Mach 3 and also climb to altitude just the same as a surface to air missile aimed at the SR-71. In the time the MIG does that, the SR-71 could accelerate, climb, an|or change direction to evade the MIG. Having intelligence as to from where and when the SR-71 was coming would probably be crucial. The MIGs could gain speed and altitude and time it to get to the SR-71 just as it arrived, giving it no time to evade. The MIG wasn’t going to loiter for long, and Mach 3 for the MIG was a one time use thing. Lastly, the predecessor to the SR-71 did carry air to air missiles. That missile would have speed and altitude advantages over the MIG i.e. it would be launched from further away or reach its target first.
  - sudosysgen 5y ago
    Of course, you cannot guarantee to intercept a target with a single plane, but that's hardly unique to the SR-71. > The MIGs would have had to accelerate to Mach 3 Not really. In any realistic interception scenario, the 2.83 Mach safe maximum speed would be sufficient to intercept successfully. Going at Mach 3 or more would be most useful in case of emergency. > could accelerate, climb, an|or change direction to evade the MIG. We are assuming the SR-71 is already at maximum altitude and speed. Changing direction is a bad idea because the SR-71 turns very slowly at very high speeds, so it would have to slow down, which is counterproductive. The MiGs were able to gain altitude around 4x as fast as the SR-71. They could get to the maximum altitude of the SR-71 and close to their maximum speed in around 10 minutes from the ground. > the predecessor to the SR-71 did carry air to air missiles The YF-12 never made it to initial service, it's production predecessor, the A-12, did not have armament. No version of the A-12 was ever made that could both do reconnaissance and carry weapons. > Having intelligence as to from where and when the SR-71 was coming would probably be crucial. Definitely. But again, you're just describing interceptions in general. Without having vectors and warning at least ten minutes (which means only 600km for the SR-71) in advance, you can't really intercept anything. Of course, a single MiG-25 wouldn't have had the best of chances. But a pack of MiG-25s would definitely have very good chances. In actuality, SR-71s were indeed intercepted by MiG-25s in international airspace.

netjiro 5y ago

The Swedes also "almost" developed a small fast business jet from a military airplane. The SAAB 105 "SK 60" military trainer had a development branch for a five seat civilian model [1]. I recall hearing it got cut sometime around the oil crisis back then. It is a quite good plane, and surprisingly silent. [1] https://en.wikipedia.org/wiki/Saab_105 https://en.wikipedia.org/wiki/Saab_105

sudosysgen 5y ago

There is ample margin of error. You forget that both airplanes are going at Mach 3+. The SR-71 might be going at Mach 3.4 and the MiG-25 at Mach 3.2, and this difference in speed is not anywhere near sufficient to prevent the interceptor from compensating. >The pilots could make course changes that would put the plane off the original intercept by miles within seconds and it was very hard for a missile to adjust for that, missiles run out of fuel very quickly and have to burn their energy to change course. And they weren't very smart in the cold war. No, that's not true. By the time the missile is fired, at a distance of, say, 30km, the SR-71 has anywhere between 10 seconds and 2 minutes before being hit. From the SR-71 flight manual, we can find a turning radius of 105 nautical miles at Mach 3.2, and extrapolate to 140 nm at Mach 3.4. That means a 259km turn radius, and a 1700km turning circumference, meaning that every degree of rotation translates to, at 1180m/s, 4 entire seconds So, the missile would have a very easy job. At a turn rate of 1 degree every 4 seconds, even in pure pursuit ("not very smart"), the missile would not have to expend much energy at all.

fakethenews2022 5y ago
What I read is that the final Soviet tactic was to “surround” the SR-71 with MIG-25s so that it had nowhere to turn. I suspect that getting to within 30km of the SR-71 would not have been easy for a single MIG. The MIGs would have had to accelerate to Mach 3 and also climb to altitude just the same as a surface to air missile aimed at the SR-71. In the time the MIG does that, the SR-71 could accelerate, climb, an|or change direction to evade the MIG. Having intelligence as to from where and when the SR-71 was coming would probably be crucial. The MIGs could gain speed and altitude and time it to get to the SR-71 just as it arrived, giving it no time to evade. The MIG wasn’t going to loiter for long, and Mach 3 for the MIG was a one time use thing. Lastly, the predecessor to the SR-71 did carry air to air missiles. That missile would have speed and altitude advantages over the MIG i.e. it would be launched from further away or reach its target first.
- sudosysgen 5y ago
  Of course, you cannot guarantee to intercept a target with a single plane, but that's hardly unique to the SR-71. > The MIGs would have had to accelerate to Mach 3 Not really. In any realistic interception scenario, the 2.83 Mach safe maximum speed would be sufficient to intercept successfully. Going at Mach 3 or more would be most useful in case of emergency. > could accelerate, climb, an|or change direction to evade the MIG. We are assuming the SR-71 is already at maximum altitude and speed. Changing direction is a bad idea because the SR-71 turns very slowly at very high speeds, so it would have to slow down, which is counterproductive. The MiGs were able to gain altitude around 4x as fast as the SR-71. They could get to the maximum altitude of the SR-71 and close to their maximum speed in around 10 minutes from the ground. > the predecessor to the SR-71 did carry air to air missiles The YF-12 never made it to initial service, it's production predecessor, the A-12, did not have armament. No version of the A-12 was ever made that could both do reconnaissance and carry weapons. > Having intelligence as to from where and when the SR-71 was coming would probably be crucial. Definitely. But again, you're just describing interceptions in general. Without having vectors and warning at least ten minutes (which means only 600km for the SR-71) in advance, you can't really intercept anything. Of course, a single MiG-25 wouldn't have had the best of chances. But a pack of MiG-25s would definitely have very good chances. In actuality, SR-71s were indeed intercepted by MiG-25s in international airspace.