I was actually thinking of the F-22, but even the F-35 is not going to be cheap. But it’s an air frame that will probably be with us for a decade or so at least, maybe more, so we should get good value out of it…as long as the Chinese and Russians don’t render it obsolete with their awesome new tech. 
How much would stealth obviate the need to hug the ground? Do you think stealth aircraft will still do that most of the time?
If so, they’d almost only be in the line of sight of aircraft which means from fighters using X band and a very small number of non-X band-using aircraft.
I suppose AESAs could be integrated within the wings and the sides of the aircraft to allow L, S or C bands while maintaining good horizontal resolution.
I think the F-35 does something like that by making the RWR do double duty but I don’t know if it can transmit in bands other than X.
Think about who Israel’s and South Korea’s likely opponents are, and none of them are likely to have advanced anti-stealth radar unless China or Russia sells it to them. Sure the F-35 will be great against developing / poor nations with 40 year old tech, but is that what the US bought it for?
You’re acting as if I’m the only one saying this, but do some reading of defense blogs and you will see that many many people ex military or analysts have doubts about stealth and the F-35 program. Here’s one example:
http://news.usni.org/2015/02/04/cno-greenert-navys-next-fighter-might-not-need-stealth-high-speed
Quote:“You know that stealth maybe overrated,” Greenert said during a keynote at the Office of Naval Research Naval Future Force Science and Technology Expo.
“I don’t want to necessarily say that it’s over but let’s face it, if something moves fast through the air and disrupts molecules in the air and puts out heat – I don’t care how cool the engine can be – it’s going to be detectable.”
This is the Chief of Naval Operations, Admiral Jonathan Greenert saying this.
Of course this is a strawman argument, though. No one (no one that knows anything at least) thinks or claims that the things are undetectable. It’s the range at which they are detected that’s the key.
The funny thing with this is that the Navy is also exploring stealthy ships at this point. Wonder how he feels about those? 
(If he’s old school Navy, he probably doesn’t think much about it, since REAL Admirals only drive carriers…nothing else satisfies. We dun need no stinkin’ stealth when we gots the BIG IRON! WE BRAKE FOR NO ONE!!!)
You are right, of course, that not everyone is a big fan of the F-35. There is a lot of criticism, especially of the engine (though the criticisms go beyond that). However, if you look back at every single US air craft for the last 50 years, they have ALL had detractors and critics. Personally, from what I’ve read, the F-35 will be a solid workhorse for us for decades to come, once the cutting edge aspects (and the fact that it’s basically a jack of all trades air craft designed for multiple roles and even multiple services) have been ironed out. From what I’ve read they are already talking about bolting in a new power plant down the line. The F-22 of course has it’s detractors as well, but it’s probably the best fighter out there today. Sadly, it’s price tag seems to be too much for even the US to swallow, so we have only fairly limited numbers of the things. So, the F-35 is going to be the backbone, and I think it’s going to do fine against anything out there. YMMV of course, but thus far I’ve seen no real evidence that stealth has been cracked to the point where it’s ‘obsolete’…or even to the point where it might be in 10 years time.
Well I plan to still be here on straight dope in 10 years time so we can resurrect this thread then and settle this. My prediction: The F-35 production run will never be completed, the the US Armed forces will be forced to replace it with a mixture of next gen partial-stealth aircraft and unmanned drones, plus upgrading the F-22. This will happen by 2025 and be due to external forces making clear the F-35 is vulnerable and does not live up to the manufacturers claims.
I’m good with that, assuming I live so long. 
My prediction is that much of the controversy surrounding the F-35 will fade away, as it has with other US air craft in the past, and it will be our work horse well into the 2020’s and beyond, and that when we develop it’s replacement THAT air craft will get slammed as well. Oh, and we won’t ever fight China or Russia directly, and they will continue to claim sooper sekrit stealth stifling sonar (yeah, I know it’s radar, but wanted to stick with the alliteration thingy going there) that will make our stealth ‘obsolete’, but it will never be put the the test in combat so we’ll be left to wonder about it, like the carrier ciller cruise crusher and Russian thunder torpedo technology tantalizer.
Thats probably true, but one of the partners we sell the F-35 to may well go up against one of the partners that Russia / China sell their fighters and SAM’s to. Presumably with Iran’s UN sanctions being lifted they are free to buy weapons from China and Russia, and Israel will have the F-35.
I seriously doubt that the Chinese and/or Russia is that far ahead of us on radar tech, but if they ARE I even more seriously doubt they would let the cat out of the bag by selling such a system to Iran or anyone else besides, maybe, each other (I also doubt we’ll be in a shooting war with Iran, and I doubt Israel will either…at least I HOPE we aren’t and they aren’t either). The thing about this speculative tech is that assuming it’s real, it’s going to be a very tightly held secret. After all, if someone uses it against us, or if we (meaning any of the various allied governments who have bought into stealth tech) get even a sniff of it we will do our best to steal the thing or at least the plans to see how it works and to do our part to mitigate the mitigation, so to speak. I just don’t see China or Russia taking that risk.
It’s not super secret. There is no way to mitigate the fact that a large chunk of metal in the sky occludes objects behind it. Build a network of optical sensors using spherical cameras on disguised towers, and use computer vision signal processing to compare previous images every 1000th of a second. When you see the image change, you use algorithms to match the shape to known hostile planes and can tell the difference between a commercial passenger jet and an F-35. At night you look for star occlusions. All it needs is fast processors and networking capability and a very large number of optical sensor stations spread out along your border. The algorithms for this kind of computer vision are public and have been for years, and processors are now cheap enough for this to be a viable strategy. Build the network of sensors to communicate in a distributed web peer to peer and you will still have tracking capability even if lots of them are taken out.
I work with computer vision algorithms in my business, and the stuff I am already using for commercial public products would be capable of doing this if you just had good enough optics and made enough of them.
And yes I know about clouds, if you don’t just use the visible spectrum in your spherical cameras then you can mostly see through them.
2 questions:
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You specifically said optical sensors. How are ground-based visible spectrum or IR optical sensors going to see beyond a dozen km or so? Won’t water and oxygen molecules severely limit the range compared to radar?
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What do you do about aircraft flying close enough to the ground (say, below 50 meters) so that they’re below the radar horizon of the towers? A 100m tall tower trying to look at a target flying at 50 meters will have a radar horizon of about 70km and that’s if we very generously presume the ground is as flat and low as the ocean. Even if the target is within the radar horizon, distinguishing it at that range would be a bitch because of the ground noise.
If you want to talk about stealth, the first thing you have to do is take a crash course on the electromagnetic spectrum and how it interacts with the atmosphere.
*I did say ground-based.
I genuinely enjoy reading these off-the-wall theories (and then watching them get taken apart).
Basically, you’re envisioning something like https://www.youtube.com/watch?t=189&v=I9QK0MkzHX4 but for jets in the wild, right?
Core,
If you want to know more about stealth, check out these threads:
OK, when I say “optical” I am meaning using a range of sensors on varying wavelengths both visible spectrum and various other spectrums nearby in order to mitigate the effects of clouds.
The way this would work is using the combined signals from all the sensors to build a 3D image of airspace, the different angles point of view would be combined and triangulated in order to pinpoint the objects position in 3D space. This is already a solved problem, 3D tracking from multiple cameras (or a single camera) is available in commercial products used in the visual effects market for effects on movies and commercials.
Eg see here:
The algorithms are freely available in published Siggraph papers. Sure it will need a LOT of CPU power and fast networking to crunch and compare the images from many many sensors, but its nothing that can’t be done using a cluster of Xeon’s and Infiniband interconnects.
And if put sensors at different heights (some 100 meters, some just above tree height) then you can solve the radar horizon problem.
Would you only be using passive sensors?
Are you under the impression that UV, visible light and IR sensors would be able to see at a horizontal distance of 100km while being ground-based?
Using UV, visible and IR optics to see 10 km away and using them to see 100 km away are quite different.
Only if the earth is flat.
Well the flight ceiling of an F-35 is 18,288m, so if we have enough sensors spread out in a grid then we only need to see 20km not 100’s of km. Place the sensors 1km apart in a grid 20 km deep along the border and link them to SAM batteries. Using of the shelf components you can probably build these for less than $20k US each sensor, then every 9 sensors go back to a Xeon cluster to process the data, then all those clusters are interconnected and talk to each other and to SAM batteries. No one sensor can 100 percent detect anything, but combining all the different angles together into a 3D image of airspace gives you what you need.
having a grid of sensors 1km apart solves the problem of earth curvature as well, there will always be a sensor at the right position to see an incoming object. Yes it would be expensive but not beyond the resources of China or Russia.
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they’d be stationary targets, against an adversary (the USAF and USN) that excels at destroying stationary targets.
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most of the scenarios for conflict with Russia or China don’t involve us invading them. It’d destroying their ships and airplanes out at sea, or over the Baltic states. In other words, the fight may not be in range of the elegant border fence you’re proposing.
There is no reason they have to be stationary, every military vehicle can have one of these sensors fitted and they communicate in a mesh network. Plus they can be disguised on ordinary houses and concealed at tops of trees. As I said above redundancy and mesh networking would mean you could still get a track even if some of them are destroyed.
Sure, but you’d bring a bunch of sensors with you and on every military vehicle and set it up over the theatre of conflict. It would advance with the front.
So, those sensors only see straight up? If a plane is 100km away from the grid horizontally, they don’t see it?
No, read what I wrote, they are spherical camera’s with a 20 km visual range, so yes the detection range would only be 20km from the edges of the grid, but thats enough range to fire a SAM at an incoming object. 20km detection range of a stealth plane is better than no detection.
Radar can likely do better than 20km against stealth fighters and perhaps even the B-2.