[sudosysgen]

The F-35 was developed to be used until 2070. It was done so at a time where it was clear that stealth could not be relied on past 2025 at the most.

Many compromises were made in the pursuit of an advantage known to become greatly diminished 10 years into a 50 year lifespan. I don't think this can be written off by the arms race argument.

[SubjectToChange]

I think you are greatly overestimating the effectiveness of SAMs. While also underestimating the complexity that stealth adds to those systems.

[sudosysgen]

Do not conflate SAMs and integrated air defence systems. An IADS that cue in interceptors and guide missiles from various different platforms is massively more capable than an SAM alone and massively more survivable.

But that's considering the system outside of the doctrine. The purpose of these air defence systems isn't going to mount an eternal and fully insurmountable wall against air power.

Rather, the purpose is to greatly reduce the initial effectiveness of US airstrikes for hours to weeks until American military infrastructure can be struck.

Stealth does not increase the complexity of radars. They simply operate on a different wavelength. This took some engineering to increase the precision but there is no reason for a VHF radar to be any more complex than an X-band radar.

VHF radars in many ways are more practical than X-band radars because the lower frequency allows for more mobile and more survivable radar infrastructure. For example, Israel struck Chinese VHF antennas in Syria. But because the antennas were relatively cheap and decoupled from processing, the Chinese were able to swap out the antennas and repair their radar in a day or two, thousands of kilometers away.

[Green_man]

Sorry, my previous comment was probably overly dismissive. I'd argue that developers and users of the F-35 already understand that stealth gains are not permanent. Countries and military organizations that purchased the F-35 definitely hope that the stealth advances last longer than 2025, but they will pay for improvements, new planes, and new tech long before 2070. It seems comically naïve for them to take claims of "2070" at face value without verifying, but that's just conjecture on my part.

[sudosysgen]

Is it? The B-52 has now been in service for 69 years. 50 years is certainly not impossible.

The trade-offs made for stealth are beyond the plane itself, the entirety of US military strategy (and even diplomacy to some extent) is deeply affected by a stealth-focused air-power strategy.

As for stealth advances beyond 2025, I don't see it personally. As long as your doctrine requires you to fly your planes over enemy radars, there's not much you can when the wavelength of the enemy radar is bigger than most features in your plane. It's a physical limit as solid as conservation of energy.

[Green_man]

I don't work in radar/military stealth, but my argument isn't that you're wrong about any of your technical claims. Rather, my argument is that the F-35 was designed and purchased by people who are at least as aware of those technical details as you are. This is an assumption, but I don't think it's a huge one. As a nitpick, the F-35 may still be operational in 50 years, just as the B-52 is operational today. The question is whether its stealth will still be useful, not whether it can get airborne. Nobody is using the B-52 for its stealth anymore (happy to be proven wrong), and the decision to lean on the F-35's stealth capabilities for 50 years won't simply be "The B-52 has been running for 69 years, nice!"

[sudosysgen]

The B-52 was never designed for stealth.

If stealth isn't very helpful, why would you fly the slow and expensive F-35? I don't really understand it.

I'm sure the people behind the F-35 were aware of these technical factors, maybe not the extent of Russian/Chinese investment though, but I don't think that their interests were anything beyond making as much money out of maintenance as possible.

As for the people making the purchases, many of them do think that the F-35 made the wrong tradeoffs and a lot of them are pushing for a plane that would fulfill the same role as the F-35 was designed for but with a very different set of tradeoffs.

[hajile]

They're now looking to retire the F-22 decades earlier than anticipated (announced a couple weeks ago).

The replacements will lose the tail fins giving much, much greater stealth capabilities. I suspect at that point that the F-35 will become far less desirable and will start retirement soon after.

https://www.defensenews.com/air/2021/05/13/the-f-22-is-going...

[sudosysgen]

The biggest reason the F-22 is going to be retired is mainly because parts are no longer being produced as much as they should have been.

NGAD will be stealthier at figher radar frequencies. The issue is VHF stealth, and removing the tailfins won't help for that.

[hajile]

If they were happy with the F-22, they'd pay to get the parts. I guess that when you pick a plane because of politics instead of capabilities, you get bitten (really should have gone with the YF-23 even if it didn't put jobs in as many states).

Stealth is NOT about becoming invisible. It's about reducing detection range until it's all but too late to intercept. Even worse, most of the ordinance those planes will be delivering will keep the plane many miles away when firing making interception time even shorter. The AGM-158 fires from around 230 miles away (575 miles for the ER variant). The S-400 can't even detect that far out let alone get enough resolution to react.

Physically smaller reflected cross-section means more stealth no matter the frequency. Giant flat panels radically increase the reflection from the side and marginally from the front.

VHF isn't magic. It's very imprecise to begin with. It's very vulnerable to jamming. It's super-vulnerable to weather patterns (a tropospheric ducting event could have most of the energy trapped in the wrong location). Longer wavelengths vs the X-band make it easier to absorb (E=hv). VHF installations are also very easy to target due to their size and massive power output trying to compensate for that E=hv problem.

Once you know a plane is somewhere within a few dozen miles, you have to send out fighters. They don't exactly have room for those large VHF arrays and those arrays aren't accurate enough to actually target. For that, they need to fall back on X-band, but that's the range that the stealth is optimized for. Once again, the stealth plane can see them from a long way off (maybe even passively) while they can't get their own lock until much closer which usually decides the winner.

[0] https://en.wikipedia.org/wiki/AGM-158_JASSM

[sudosysgen]

We are no longer in the 1960s. VHF radars now use AESA and have home-on-jam capabilities. Missiles have dual or even triple guidance systems.

Cross section is not a number you can compute in a vacuum. The cross section is associated to the frequency of the wave.

It's not viable to use AGM-158s for everything. When running these missions you are racing against time, you need to deliver the most munitions as fast as you can without missing faster than the enemy can strike your supply lines, bases, and carriers.

"Somewhere withing a few dozen miles" is a wildly inaccurate characterization. VHF AESA radars are accurate to 350x100m, and this number is improving every year as radar processing techniques improve.

Yes, the fighter can detect the radar from farther than the radar can detect the plane. This is true of every single radar system. The issue is that the fighter can only fire blind weapons unless it moves away.

That's the issue with the AGM-158 and other standoff weapons - the radars it's targeting can pack up and leave in a minute. It will then hit an empty field. Meanwhile you're making your attacking fighter jets a lot less stealthy carrying it.

And 350m accuracy is more than enough for a huge tactical advantage. The stealth jet has to use its radars to lock onto the other fighter jet, while the defending jet can launch munitions without turning on its radar at all or until it is way too late.

They also can't pay to get the parts that easily. It's not how these kinds of projects work. The people that designed much of it are dead or retired and the production lines are closed. Planes have to get cannibalized sometimes. Opening the lines back up after they are closed can be extremely costly and technically difficult and can involve reverse engineering.

Longer wavelengths are actually harder to absorb. I don't know where you got that they are easier to absorb? You need a lot more material to absorb a wave of longer wavelength of the same material.

E=hv is the wrong equation, because the amplitude is not fixed - the power is fixed. Larger wavelengths means thicker elements that can carry much more power without running into cooling limitations.

VHF isn't magic. Stealth isn't magic either. You can't avoid scattering and diffraction, these are physical limits. They limit VHF radar accuracy too because of the basic Rayleigh scattering equation, but you can fix this by making your aperture larger and applying some clever processing algorithms. If you're a plane, the only solution is to become bigger. Which is much more difficult.