During its career, the SR-71 Blackbird gathered intelligence in some of the world’s most hostile environments. The SR-71 was conceived to operate at extreme velocities, altitudes and temperatures: actually it was the first aircraft constructed with titanium, as the friction caused by air molecules passing over its surface at Mach 2.6 would melt a conventional aluminum frame.
No Blackbird has ever been lost or damaged due to hostile action: in fact, even though according to Airman Magazine over 4,000 missiles have been fired at the SR-71 during its service life, none of them hit.
How was the Blackbird able to outrun, or otherwise successfully avoid, Surface-to-Air Missiles (SAMs)?
‘It’s an issue with intercept geometry,’ says famous writer, former Naval Aviator and Aerospace Eng Tim Hibbets on Quora. ‘[For instance] the SA-2 missile had about Mach 3.5 worth of giddy-up versus the nominal Mach 3.2 of the SR-71. That’s great, but the SAM had to launch, accelerate, climb, and track to the plane. This took time; time that the pilot was using to transit the danger zone (cue music). Here’s a graphic showing the effective envelope of the SA-2 against a moving target.
‘So, you can see that engaging against a Mach 1 target is child’s play, with the comrades with coffee cups pushing buttons on Studdly McFighter while he’s still out past 20 nm, all the way to 2 miles for a normal altitude. Meanwhile, the dudes with the space suits just have to stay outside that little red bit in order to keep pulling in flight pay. And mind, they are getting radar warnings and simply have to turn a little left or right if they aren’t feeling sporty about it.
‘Also, realize the Blackbird is transiting that four nautical mile window in about 6 seconds. It’s enough to make a SAM operator cry.’
More info on the graphic featuring the effects of speed and altitude on SA-2 SAM is provided on Stack Exchange.
The Intercept geometry in fact is the bubble of space in which the SA-2 missile can be effective against a specific target [aircraft]. Crucial is the detection range of the radar system guiding the missile, given here as 40 nm.
Since the SA-2 has only a limited time to ascend to the altitude of the target and to close in, the combination of speed and altitude of the SR-71 (1854 kt, moving at more than 30 nm per minute) leaves only very small intercept geometry. Moreover the Blackbird has to overfly the missile launcher almost directly to be vulnerable. If the SR-71 flies above 90.000 ft and Mach 3.2 (or employs effective countermeasures), it will be unassailable by the SA-2.
By contrast if an aircraft is flying only Mach 1 at 60.000 ft (which equals 573.6 kt, moving at less than 10 nm per minute), its course can go past the launcher with a 25 nm offset and being in range of the Fan Song – SA-2 combination.
As we have previously reported, the only published and U.S. government-acknowledged missile firing at an SR-71 occurred on Wednesday Aug. 26, 1981. As told by Col. Richard H. Graham, USAF (Ret.), in his book The Complete Book of the SR-71 Blackbird: The Illustrated Profile of Every Aircraft, Crew, and Breakthrough of the World’s Fastest Stealth Jet, SR-71 pilot Maj. Maury Rosenberg and Reconnaissance System Officer (RSO) Maj. E. D. McKim were making their final pass on the DMZ, heading southwest, when North Korea fired two Soviet SA-2 surface-to-air missiles (SAMs) at their aircraft. Major McKim was the first to notice anything out of the ordinary by his DEF system [the Defensive Electronic systems that were designed to jam or spoof any radar or SAM system as necessary and were carried in SR-71’s chine bays] automatically jamming the missile’s guidance system and lighting up his cockpit displays. After he informed Major Rosenberg of his DEF indications, he looked out to the right just in time to see the missiles scream by. The incident caused quite an uproar in the press, and crews became much more cautious in future passes through the Korean DMZ.
Photo credit: U.S. Air Force
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The crew that flew over Lybia after the F-111s stated they were "seeing mach numbers they hadn't see before" to out run a SAM. I'm guessing that means in excess of Mach 4. Also, what were the stats of the black bird against the SA-5? If I recall correctly the SA-5 had better performance than the 2.
The aircraft was heated by the compression of air in front of the aircraft. That's why the leading edges and nose get the hottest. Friction plays a very small role in heating. Otherwise you'd see the highest temps where the relative speed is the highest, surfaces parallel with the airflow.