I suspect the future won't be "super weapons" like the F-35, but instead just "mass" weapons like tens of weaponized drones. Where the mission isn't to be invisible but to simply overwhelming enemy defenses (essentially the World War I strategy, but without the massive numbers of dead soldiers).
PS - The people pointing out that the F-35 had radar reflective disks added didn't seem to have understand the article (or technology). This is using entirely different methods to detect the aircraft, not radar waves, so that's irrelevant. The F-35 could be broadcasting a transponder, and it wouldn't undercut the technology discussed.
It is relevant, and this system is absolutely using radio signals for detection and tracking; it just doesn't transmit them. The system described is a bi-static radar system that uses transmitters of opportunity (technical term "non-cooperative transmitters") to generate the signal and listens for the return from those signals hitting the target.
Now, their system may be using EM blocking as part of its tracking. The principle here is that a low-observable aircraft creates a "hole" in the background because it absorbs or scatters EM radiation away from the receiver. This method works best when the background is very noisy (i.e., there are lots of transmitters operating in the area). In that case the reflectors (and anything else that increases the radar cross section of the aircraft) would actually hurt the performance.
I have to disagree. Manufacturers will continue to build stealthy planes and drones, simply because it makes it harder to detect them. Yes, you may be able to detect a stealthy plane at, say, 100km, but using the same techniques you would be able to track a non-stealthy plane at 200km. Stealth isn't an end-all be-all tool that makes vehicles completely invincible, as the Bosnian shootdown of the F-117 showed, but it does make it harder, and I don't know of any technologies that could render it completely useless.
If the stealthier choice adds cost, weight, or maintenance costs, decreases top speed, maneuverability, or MTBF, the better choice may be the less stealthy plane, and if being stealthy gets harder, the choice may be more often that of extra speed, extra weaponry, or more airplanes.
I think this point of view will come to be seen as anachronistic, much as the WWI strategy was not long after WWI.
Why? There is a fundamental disparity between the complexity needed for a forward-operating offensive weapon, and the complexity needed for domestic defensive weapons. Offensive drones need to avoid defenses and navigate to a particular target. Defensive drones just need to interfere with the offensive drones.
Any offensive strategy you can think of that depends on simple numbers, can be countered with numbers at lower cost. If it's drones, I can build more defensive drones than you can build offensive drones for the same total cost.
Mobility can complicate that picture. If I have a million attack drones, and you have a million defense drones, there's still the question of where you put your defenses. If you have a hundred cities to defend, you might realistically need a hundred million drones.
An attacker only needs to pick one area and overwhelm it, the defender needs to pick ALL targets and produce enough to defend all of them.
Defence vs drones is a LOT more expensive than the attack.
if it's so simple, why are there presently no defensive drones?
This. One solution is to simply deploy a considerable number of ground and orbital (or even use blimps/balloons like some companies want to do for wireless internet, or for quicker deployment during a developing incident a fleet of autonomous drones) IR sensors and simply follow the exhaust, with low enough latency and a little predictive maths you could probably know where an aircraft is, and will be, for the next several seconds at any given second with an almost perfect degree of accuracy unless the aircraft is actively conducting evasive maneuvers.
Tie that together with traditional radar, x-ray, terrestrial radio broadcasts, etc and you can make a system that would be hard to evade detection from.
The larger an area you are attempting to detect aircraft in, the harder it would be, but you could protect specific facilities by deploying much smaller grids over likely approach paths with say ground based IR sensors to detect exhaust trails of anything on approach and then in a much tighter area close to the strategic target.
You could also probably deploy atmospheric microphones in blimps/balloons that report their location with GPS and use some sound detection algorithm to detect aircraft moving away from them and use a network of such microphones to dial in an approximate location, heading and speed. Not unlike commercial gunshot/shooter detection systems that already exist.
Passive radar is just radar that takes advantage of existing radio broadcasts (such as TV and radio stations). This particular passive radar setup may well use a different frequency range than military radars, but it's still working on the same basic principle of any other radar.
It seems plausible that a plane equipped with RF reflectors would reflect a broad range of signals, and that a skeptical person could reasonably want an explanation of any claim that the reflectors are in fact non-reflecting in the relevant bands.
This is basically the endgame that Diamond Age predicts.
For those not familiar, the book describes nanotech drones on the scale of dust mites, and cities protected by essentially artificial immune systems.
When a battles occur in this setting you can tell because everything is blanketed in soot, the microscopic corpses of dead drones.
Lots of cool ideas in that book, tech and otherwise.
Diamond Age is slower and for me a lot of the plot and characters are less memorable, but the world, tech and ideas are amazing.
Snow Crash is a force of nature. That manic, brilliant opening set up of the world, style and characters using the Deliverator blows my mind every time.
Hard to believe it's even the same author.
I had the same thought when I read Zodiac, after first reading his later novels. It makes Snow Crash more clearly part of a progression.
The difference is plausible deniability.
Stealth weapons let one plausibly deniably launch attacks. (Perhaps to the point of letting the attacked pass it off as an accident, which could let them save face when returning to the negotiating table.)
Swarm tactics have no such deniability (though attribution can be complicated if non-state actors are used as a front).
On top of that a cruse missile takes around an hour to reach a target making them of limited value vs a mobile target. They have real value vs thinks like air defenses or high value buildings, but building hundreds of thousands of them is never going to happen.
With precision guided weapons, you don't need half a million bombing missions.
Though again flexibility to chose targets at the last minute is extremely valuable. Cruse missiles are simply a poor choice vs tanks.
I rather hope the US never does anything like this ever again. To this day people in Vietnam, Cambodia and Laos are still being injured, maimed or killed by the hundreds of millions of bomblets they dropped.
I think the recent attack on the refinery with 18? Drones and 7 cruise missiles (3 fell short?) could be referred to as “bombardment”.
The pitch I've seen in settings that do have subject matter familiarity is that stealth decreases the detection range for a given power / bandwidth / noise tolerance. Could your opponent use more power? Sure, but then they're easier to missile lock and destroy. Could they use more installations? Sure, but then they have to maintain them and their communications. Could they crank up the sensitivity? Sure, but then they have to deal with false positives and increased vulnerability to jamming. That goes especially for passive radar. Don't get me wrong, it's still an arms race, but it's not as cut-and-dry as this piece would have you believe.
Also, it's a VHF technique, which is low enough frequency that I'd bet active cancellation is practical, possibly even through a software update :)
A lot of this stuff is literally an arms race, along multiple dimensions. Want to active-cancel the VHF signal? You'll need a transmitter for that. How many can you miniaturize into your fighter, and how many can they fit into the installation on the ground?
Another way that it's a race. You have to detect the signal quickly enough and recognize that it's a signal, and then jam it before they can get enough return to discern you from the noise.
So there was always a matter of economics/engineering here, and one valid criticism of the F-35 is that it costs a lot for what it's doing, and any way that chips into its advantage (in a way that is actually production-ready, and not just an irreproducible hack) shifts that cost/benefit balance.
It only tips the table, though. By using ambient RF it is very difficult to track, but very easy to spoof and mess with.
How well would it deal with a dozen drones omnidirectionally blasting the star-spangled-banner at high amplitude over FM with a bunch of wacky reverb (and maybe a few leads/lags chosen to look like scattering)? Traditional active radar wouldn't have the slightest problem rejecting interference at that sophistication tier, but most passive radar systems would have a tougher time.
As for stealth,
> Want to active-cancel the VHF signal? You'll need a transmitter for that.
Like antennas in the skin hooked to software radios with resilient analog front ends? To my ears, that sounds like a bet that payed off.
> How many can you miniaturize into your fighter
A few, probably. That's not enough to do active cancellation at microwave wavelengths, but it might be enough to do active cancellation at VHF.
> You have to detect the signal quickly enough and recognize that it's a signal
With active radar, that's the game. With VHF passive radar, you characterize the "ambient" radiation, which in this case probably boils down to mapping the FM stations. It's public information, and that is both the greatest strength and the greatest weakness of passive radar.
They've been well known since that a F-117 was shot down in 1999 during the Serbia conflict. The actual event was mostly due to bad operational tactics on the American's side and a very lucky shot, but it did highlight that it was possible to detect stealth fighters using coldwar-era Soviet technology.
The problem is that the stealth is specifically geared towards XHF frequencies, which are the frequencies used in radar guided missiles.. which are the favored missiles for the USA.
However the planes lack the physical size and features necessary to completely absorb VHF radar. VHF lacks the resolution necessary for guided missiles and VHF radar stations must be very large, but it can be used to monitor air traffic over vast areas.
So if you detect a aircraft on VHF and then point your XHF radar at it and nothing shows up... Then you know you are dealing with a USA stealth fighter.
Stealth has been heavily oversold to the American public, but foreign governments are not so vulnerable to USA industrial-military propaganda.
This doesn't mean that stealth is worthless. It does dramatically reduce chances of detection, just doesn't make them invisible. They are still largely invulnerable to radar-guided missiles. The size of VHF radar arrays needed precludes their use on other aircaft.
So to make this sort of thing still requires a sophisticated network connecting large and easily found radar stations, which themselves can be targeted and disrupted in a combat environment. There is still major hurdles needed to solved before it would be possible to actually shoot down these aircraft with radar-guided missiles.
Also this technique doesn't work as well against aircraft the size of B-2 bomber.
Problems with the article:
- The F35 isn't flown to air shows in 'war mode'. It has a bunch of reflectors added to increase its RADAR signature. It is only naked when it might be used in anger or over test ranges, and the USAF is very careful to make sure non-JSF program RADARs are off, or have the recordings deleted.
- Passive RADAR is a real thing that works, but it only gives a general location. It would be meaningless to try to send a link track to an interceptor or SAM site from a passive RADAR system -- all you could do is call and say "look sharp chaps".
- When you want to shoot at it, your S band (ground) or X band (interceptor) RADAR will have a very hard time picking it up or maintaining lock (because its signature changes depending on aspect, and obviously the pilot will manoeuvre to minimise). Meanwhile your ground receiver is getting jammed and transmitters are getting blown up by JDAMs.
- Passive RADAR can also be jammed and deceived. How many times will you scramble interceptors for a false passive detection?
A radar manufacturer claims they can detect an F-35 which was equipped to be detectable but the radar maker claims that the devices uses to make the plane visible to radar didn't matter because they were tuned to a different frequency.
They're just selling radars.
The thing about stealth is that a tiny aberration can turn an invisible plane into a flying barn. It doesn't matter if the devices used to make the plane visible were for different bands, it's radio, nothing is exact. They obviously made the plane visible to more than just the target design.
On another level, there are various maintenance things that are done to make the plane stealthy when in operation that wouldn't be done going to an airshow.
And finally, no one says the F35 is totally invisible to radar in all circumstances. It is especially detectable after it has passed your current position. The value of the stealth is that you don't detect it until it's on top of you or has already fired on you.
In a real air-superiority fight, F-22 and whatever other classified drones and planes would be the first wave and clear out a path for the less stealthy but more versatile F-35.
As for knowing when and where the planes were flying, true, true. But then again, they deployed one van to try to detect the planes, in the one farm, and if the objective was to suggest that the passive technology could end up being useful in a military situation, that might be enough.
The argument is that the F-35 is invisible. If passive detection seems to have any effectiveness, even slight, in detecting F-35s, that ought to guide investment into passive detection and into upgrading the F-35’s stealth to avoid passive detection.
INAE, but it feels like there is enough here to cast the claims of complete invulnerability to detection in doubt.
Edit: fixed seeker range
You obviously need strong signals for passive radar to work but those could be positioned inland and they don't need to be where the passive radar is, making it harder to disable it.
I would really love to see the actual Probability of Kill numbers for the US missile fleet. I know that's never going to happen/they're going to remain classified for a _long_ time, but the kid in me really wants to know "does it actually work?"
Air-combat is "hard" to answer the "does it actually work" because it is very much like high stakes chess in the air. A lot of times you fire 1 missile to make the bogey defensive, and multiple missiles to kill. This gets even more complicated when you factor in differences in pilot skill, numbers, chaff, and electronic counter measures.
Yes, they each span a wide range of frequencies, but every frequency range spans a wide range of frequencies. These two are as close as you can be.
Not coincidently, VHF Radar is defined to be between 50 and 330Mhz, which actually overlaps both Microwave and VHF television.
Now as to the main question, if I set up a device to interact with radar at some frequency and attach it to a stealth airplane, what frequencies would you expect it to effectively interact with it (assuming it's tuned at all, they could just be attaching a big piece of flat aluminum)?
Answer: If my device has peak interaction at frequency F, you will see harmonics, so you will see significant interactions at 1/8 F, 1/4 F, 1/2 F, F, 2 F, 4F, 8F.
Airport radar is around 3Ghz. So if the radar reflector operates at around 3Ghz, it will also work pretty well at 1.5Ghz, 750Mhz, 375Mhz, and even 187.5 Mhz. 187.5Mhz is TV channel 6 or 7, depending on country. Half again is 93.7 is FM (which the article specifically mentions).
A tiny radar reflector has the cross section of a huge object, because it intentionally has right angles that send signals back to their source without scattering them in other directions (as much as is possible).
Passive radar still requires the object to reflect signals, it just doesn't require the signals to be reflected back to the source of the signal. Consider a monitor with an anti-reflective coating (so lets take a non glossy monitor). It is effective at reducing the reflection of the window behind you, it uses a thin film to cause destructive interference so that the light coming in the window not reflected, and you see a greenish-purplish image of the window instead of getting a bright reflection. However, if you take a flashhlight and shine it down on the monitor from near the top of the monitor, you will easily see the glare from the flashlight as it illuminates the monitor.
I think this is a good analogy for active vs passive radar. The F-117 was built to avoid right angles, this is like the light from the window behind you. The F-117 won't send radar back in the same direction it came from, so active radars are thwarted. However, if it is being 'lit up' from somewhere else, it is not as effective since by not sending radar back to where it came from it sends it in other directions instead.
However, it also has a coating to just straight up absorb radar. The F-35 is much more reliant on such coatings, and so it should scatter very little EM radiation in those frequencies, regardless of whether the detector is in the same location as the transmitter.
You will not see harmonics at fractional (1/2 F, etc...) frequencies of the fundamental, though you will likely still see some backscatter.
Retroreflectors, to include the Luneburg lenses mentioned in the article, function by directing radar energy parallel to its incidence direction. These reflectors will not significantly increase the plane's RCS for passive/bistatic receivers. Even if these reflectors did increase RCS omni-directionally, it is unlikely that a reflector designed to operate at 3 Ghz (10 cm) would also be designed to operate at 187.5 MHz (1.6 meters).
I mean the goal of a radar reflector is to send radar signals back to their source, they are super effective. They don't really work like antennas generally, but the pictures of the F-35's reflectors do not look typical, or like a boat's radar reflector, and I have no idea what principle they use.
Sensitive VHF radio receivers, tuned to transmitters that are located beyond line of site, can very easily detect VHF communications reflected off of a very small airborne target.
I can sit in my office with a spectrum analyzer and watch the signal strength of a distant digital TV broadcast station come in and out of view when an aircraft flies overhead.
Couple that technique with a DF network and far more sensitive receivers and GPS timing, and building a passive radar to defeat stealth technology become far easier than you think.
More interesting would be whether those planes actually had the full stealth coating and various other "stealth settings".
It's hard to get your head around a plane the can climb over 1000 feet per second (F22: 62,000ft in 60 seconds).
The important question is whether or not they can pick it up when it doesn't have markers fitted as they claim they can. To quote Carl Sagan, 'extraordinary claims require extraordinary evidence'. If (and it's a huge if) they can do what they say they can then stealth might be rendered pointless, and that changes a lot.
Even if you discount all the possible issues like the F-35s not being in "stealth operational mode", having reflectors, etc.. this is not a real world test at all.
In the real world test there will be a massive amount of ECM energy hitting this passive radar... it might totally blind a sensor like this. In addition a lot of the civilian radio frequencies/transmitters will be getting knocked offline and it won't have it's energy sources.
On the other hand, the algorithms behind passive radar might depend on knowing where the transmitters are. Maybe one could triangulate the drone directly, but not so easily if you have multiple drones transmitting short bursts asynchronously. And if there are enough decoys, it would be like chaff.
That's a very good point which I neglected to consider.
"Passive radar equipment computes an aerial picture by reading how civilian communications signals bounce off airborne objects."
Once you start emitting you're not stealth anymore, and you can be shot down pretty easily. Same with carrying external ordnance. Same with worn out radar absorbing coating. Same with any physical defects on the plane's surface. That's why these planes are designed to only be stealth in the first few days of a real, actual war, and then once they get scuffed a little by e.g. bullets or debris you're supposed to treat them like regular fighters and not rely on their no longer existent stealth.
You can't optimize your civilian transmitters to send out signals best for radio detection and ranging, so you lose accuracy. Better than nothing.
EDIT: The Spiegel reports more or less the same story, occurred in Aptil 2018. The radar comes from Hensoldt, a former Airbus subsidiary.
And, as already stated in another comment, it was passive radar in the sense it took existing signals and analyzed them and their absence.
EDIT 2: Yeah, submitted article reports the same story... Lazy me...
Whenever someone looks at the F-35 and others, you should aim to build a holistic picture of what 'X' feature serving sub-optimally could entail, not just "Invisibility cloak has weaknesses under these specific conditions, therefore it is a failure" and whether the group behind optimizing the aircraft is aware of it and accounts for that when upgrading and /or sending it on missions.
Turn on your TV to a UHF digital channel during the demo. Watch the interference. Now, it could all be reflectors, but you get a sense how a bistatic RF detector could work.
If not well that could be a game changer
A bit of Google suggests that they are indeed frequency specific see link. So that sounds like it has real potential
These lenses presumably have some isotropic scattering at the frequencies used by this passive radar, and the question is, how much?
Nothing is designed to be undetectable by "radar." "Stealth" aircraft are designed to be "invisible" (low-observable, really) in one or more radar bands. Once you get outside those EM bands, the aircraft is obviously detectable (e.g., you can see it because your eye doesn't operate in the X band).
Don't know your background, so I apologize if this is old info for you: the band of radar you use is driven by the size of the antenna, which is why pretty much all fighter radars are X band (maybe +/- a little bit). You only have so much space in the nose of an aircraft, and that becomes a constraint for what radar frequencies you can use. If you know that, and your goal is to not get shot down by enemy fighters, you can optimize your radar signature for that threat.
To me, this article is like saying something like "bullet-proof vest defeated by falling boulder." My reaction is well...no...not really....
(or, if you prefer, maybe the jets used for demonstrations are intentionally damaged in visible ways so that there is a convenient excuse for the ease of detecting them on radar)
edit: I was thinking of the F-22, see comments below for a source. But similar considerations probably apply to the F-35.
However you're no doubt correct that radar absorbant materials is high maintenance on any aircraft.
Whether any electronic system would help against passive radar, or would in fact make things worse, is another question.
I always warned that the F35 is a one trick pony. Can't fly fast, can't fly far, can't carry much load, can't dog fight, needs ton of maintenance and may or may not be invisible.
By definition, no plane can be invisible. It is a questions of frequencies and angles you look at it. This plane was not build to bomb Syria or Iran. If the German radar can see it, they Russians and Chinese can detect it for sure.
that is exactly all the "can't"s the F35 ancestor - Yak-141  - was designed with. All the stealth and quasi-fighter related capabilities of F35 are just bolt-ons onto that design in an attempt to mitigate the "can't"s and to stretch if even just a bit the very limited otherwise capabilities of that design. The only "can" in that design, its raison d'être, was the VTOL with swiveling nozzle (which can't even vector in flight). While that swiveling nozzle is a great thing for a country with no capabilities to build real aircraft carriers, it is a thing born in the pre-stealth age, and thus naturally compromised the stealth (especially in IR) of F35 as there is no way of making it "flat rectangular", like for example on F-22 and B-2, at sane (even by DOD standard) costs.
What's really damning about this news is that it calls the entire value proposition of the plane into question. By which I mean, every time someone like me points out that the F-35 loses dogfights to planes from two generations ago, the apologists always come in and say that doesn't matter because the stealth and ECM technology means it will never be in dogfights, only BVR engagements.
But if you think about, that statement is essentially a gamble. It's a wager that our stealth and ECM technology will always, for the entire 40+ year projected lifespan of the plane, be ahead of competitors. Is that a safe bet? I don't think it is. This news shows it, and that's only what's publicly admissible. Imagine what Russia and China have that they're not talking about.
This thing is a piece of junk based on multiple failed ideas (V/STOL, stealth and ECM obsoleting actual combat performance, on-the-fly development, etc.) and it needs to be scrapped yesterday and started from scratch.
The F-35 angled at not just its combat capabilities but at a NATO wide domination of combat aircraft, including operations for the full operational life for all operations of these planes. Almost worked out, and my still do.
Even for that opening stage of the battle, I would suspect that cruise missiles and drones would make more sense.
Would kind of make sense, IMHO, to have a superior, super stealthy dog fighter that can serve as a drone "mothership". Supplemented by droves of cheaper, non-stealthy specialized planes for ground attack, recon, bombing and whatever nasty fun things a future air force might dream of. Otherwise I think the next world war starts with zhe equivalent of a X-Wing and ends with the use wooden bi-planes.
> It strikes me that having an entire fleet of high stealth aircraft is only going to be important for... maybe the first 48 hours of any conflict.
It goes against the generalist, jack-of-all trades dogma; but I think the air force should have cheaper non/less-stealthy designs of equal or greater performance for almost every role occupied by a stealth plane.
It should also be noted that in stealth '5th gen' drone vs '4th gen' drone simulation, the stealth drones win convincingly, not because they are 'invisible' but because they can shoot first, before the other drone can get a lock.
Personally I think we're more likely to see '5th gen' drone wingmen. Finally each SQNLDR will have their own squadron, albeit robotic. With short range comms are much harder to jam, but it's uncharted territory to see how the leader will guide the engagement.