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Comment by djyaz1200 | Hacker News Reader

The way to defeat stealth is instead of looking for the size of the object look at speed and trajectory. The B2 famously has the radar cross section of a honeybee. No problem. I would just build filtering software for my radar that said show me all the objects of any size (even Bee size) heading my way at over 300mph. I'm sure this has been done, and it's alluded to in book Skunkworks (good book btw).

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Actually a better approach is to use longer wave radar, getting a reflection from the whole metal airframe as a conductive object rather than just bouncing waves off the surface. Apparently this technique has difficulties with clouds but was successful in shooting down an F117 in the Balkans.

Yep, that would be better. IMO the broader point is that stealth isn't magic. Just like any other tactic it has countermeasures... and pretty cheap ones. IMO this should be discussed more as our country pours billions into stealth aircrafts.

Another way is bi-static radars. Stealth is generally designed to prevent returns from going back to the sender, with the downside that they get scattered in all other directions. Just setup a (silent and difficult to locate) receiving station(s) and give it a communication channel to the sender (to synchronized), then it will receive the emissions from the sender that bounce off stuff.

Another way of using bistatic radar is to look for holes. Pick a frequency band that has significant background noise and search for places where the background is consistently lower than average. Essentially, invert the detection algorithm. Nice thing about this approach is it can be done non-cooperatively; that is, the EM sources do not need to be controlled by whomever is running the receiver.

Correct, but long-wave radar suffers terribly from noise, I believe. The difficulty is finding a tiny needle in the proverbial very busy, noisy haystack.

The F117 shootdown over Serbia had the advantage of having been able to tap the NATO radio network, and subsequently position their AA batteries according to that information. Even with that they only had a 20 second window or so to fire whilst the F117 had its bomb bay doors open.

I wonder if the B2 or F-22's radar profile is similarly expanded noticeably enough to stand out amongst the noise in long-wave radar during bombing runs. I doubt we'll known that with any certainty for 20+ years, if at all.

The point of stealth isnt that you are never spotted by radar, but to make it more difficult to target and track on meaningful timeframes. Think of a normal aircraft as an orange road cone with reflectors. Shine a bright light on it and it can be seen for miles. A stealth aircraft is a matte black speedbump just barely above the normal road height. Even with a really bright light you'll have to be extremely close to see where exactly it is on the road. Meanwhile from the speedbumps perspective they can see the guy shining the bright light clearly.

When people talk about a small RCS they arent hoping to blend in with other 600mph hummingbirds. They simply want to avoid being spotted until it is too late for the enemy to do anything.

You think that radars don't already have extensive filtering for clouds (otherwise it becomes a weather radar), birds and the like? What makes you think a bumble bee signature is readily trackable? Also, do you think radar engineers miss obvious solutions, and that you'd make a good engineer at Raytheon? Maybe you should apply.

I'm simply pointing out that stealth isn't magic. In any battle it's good to spend time thinking about how you would kick your own ass. That makes you better.

Isn't there also the issue of missiles needing an object to look for as well? IIRC, missiles are often measured by the minimum RCS (radar cross section) needed for a successful targeting + hit.

Yes, I'm (conveniently) separating the problem of detection and destruction here.

Sounds easy but in practice it's not. There is a surprising amount of high speed things flying around at altitude. Not to mention that RCS reductions aren't always just about reduction, but also obfuscation.

Yeah, acknowledge things are always easier said than done and this is still a very complicated problem but fundamentally it's a pattern recognition puzzle that could be solved IMO.

You'll still get all sorts of micro-meteorites even with that. I'm not saying it's not a smart compromise, but it's still prone to false positives. Better than nothing, I guess.

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