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America's Fastest Spy Plane May Be Back -- And Hypersonic (bloomberg.com)
A Lockheed Skunk Works executive implied last week at an aerospace conference that the successor to one of the fastest aircraft the world has seen, the SR-71 Blackbird, might already exist. Previously, Lockheed officials have said the successor, the SR-72, could fly by 2030. Bloomberg reports: Referring to detailed specifics of company design and manufacturing, Jack O'Banion, a Lockheed vice president, said a "digital transformation" arising from recent computing capabilities and design tools had made hypersonic development possible. Then -- assuming O'Banion chose his verb tense purposely -- came the surprise. "Without the digital transformation, the aircraft you see there could not have been made," O'Banion said, standing by an artist's rendering of the hypersonic aircraft. "In fact, five years ago, it could not have been made." Hypersonic applies to speeds above Mach 5, or five times the speed of sound. The SR-71 cruised at Mach 3.2, more than 2,000 mph, around 85,000 feet.
"We couldn't have made the engine itself -- it would have melted down into slag if we had tried to produce it five years ago," O'Banion said. "But now we can digitally print that engine with an incredibly sophisticated cooling system integral into the material of the engine itself and have that engine survive for multiple firings for routine operation." The aircraft is also agile at hypersonic speeds, with reliable engine starts, he said. A half-decade before, he added, developers "could not have even built it even if we conceived of it."
"We couldn't have made the engine itself -- it would have melted down into slag if we had tried to produce it five years ago," O'Banion said. "But now we can digitally print that engine with an incredibly sophisticated cooling system integral into the material of the engine itself and have that engine survive for multiple firings for routine operation." The aircraft is also agile at hypersonic speeds, with reliable engine starts, he said. A half-decade before, he added, developers "could not have even built it even if we conceived of it."
In part. Satellites are conveniently cheap(when amortized across the amount of area they cover; and how long they cover it; they are not 'cheap' in terms of sticker price); but don't fly any lower than earth orbit and are predictable against any vaguely competent adversary(tracking satellite launches is a hobbyist thing; and downloading their conclusions to know when you are being over-flown is easier still); and continuous coverage requires either lots of satellites to blanket one of the lower orbits; or satellites in geostationary orbits which are quite distant and have the accompanying challenges to getting good image quality.
If you really need a surprise inspection of a specific place at a specific time the gap isn't really filled; but having satellite sensors to work with keeps you from being in the dark; and you can use drones or less capable aircraft in places where adversary air defenses aren't all that interesting.
Nothing quite fills the niche; but filling the niche is an expensive specialty operation; and one that might become quite risky if anyone is capable of pumping out SAMs of similar tech level; since they don't have to support a pilot or a bunch of cameras; just have to hit you; which makes outrunning them without being substantially more advanced a bit nerve-wracking.
Not quite, but it's still quite a lot. At 85,000ft the speed of sound is about 300m/s (690mph) which is about 88% of that at sea level (340m/s). So at 85,000ft and Mach 5 it'll be travelling at about 1,500m/s (3,450mph). Depending on how many g the pilot wants to feel the turn radius might be as high as 343km (213mi) at 1.2g and as low as 47km (29mi) if the airframe can survive a 5g turn (the SR-71 had a limit of about 3g).
Because I like speadsheets, for a given g-force that the pilot feels, the turn radius & time to do a u-turn.
g(pilot) - radius(km) - radius(mi) - time
1.2 - 343 - 213 - 12:02
1.5 - 204 - 127 - 07:08
2.0 - 132 - 82 - 04:36
2.5 - 99 - 62 - 03:29
3.0 - 81 - 50 - 02:49
3.5 - 68 - 42 - 02:23
4.0 - 59 - 37 - 02:04
4.5 - 52 - 32 - 01:49
5.0 - 47 - 29 - 01:38