Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Czech Passive Radar Detecting B-2 at 150 miles (2015)

defence-blog.com

Post reply on HN
Print view View original

111–120 of 125 posts

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#111

Post by heavenlyblue »

nnq wrote: post #109
lazyjones wrote: post #7

What would air defence against a swarm of a few 1000 UAV look like? Because China...

You'd need a breakthrough in battery (or other form of energy) technology - eg. high range + cheap as hell ...I don't think/hope China will be a world leader on this anytime soon :) Ofc you can low-tech your way into it by just delivering drones in shipping containers and hiding them close to potential targets... Also, cheap ass drones + bio-warfare would make a killer combo, if you knew you won't get nuked if you im…

UAVs don’t have to be battery-powered; don’t mistake them for quadcopters.

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#112

Post by raducu »

sfifs wrote: post #58
JDulin wrote: post #47

Earlier quoted context omitted.

More to the point, detecting a stealth aircraft is very different from shooting at a stealth aircraft. This radar would likely not have the location accuracy of where exactly the B-2 was to accurately engage it with a missile. Your accuracy would be limited by the rate of RF pings the B-2 is putting off, and then the margin-of-error of these RF waves and receiver. This is one difference between the B-2 and stealth fi…

If you can localize down to the range of a km? Can't you just shoot down optically? A giant dark plane blotting out the stars...

I'm sure any modern IR missile can shoot down any current stealth plane if it knows the location to within a few kms.

There are FLIR images of thr F22, nothing extraordinary about it in the IR spectrum.

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#114

Post by throw0101a »

ChuckMcM wrote: post #26

Hmm, not your typical RADAR. This is basically using the RF emissions of the plane, and their detection at multiple RF detection stations with synchronized clocks, to determine the difference in arrival time. The radio emissions all travel at the same speed through the air, the difference in arrival time can be used with some simple trig to figure out where the RF emitter is. There are a number of Time Difference of…

> ... their detection at multiple RF detection stations with synchronized clocks, to determine the difference in arrival time.

I believe this is generally called multilateration (MLAT):

* https://en.wikipedia.org/wiki/Multilateration

* https://www.skybrary.aero/index.php/Multilateration

* https://www.sciencedirect.com/topics/engineering/multilatera...

* https://www.navcanada.ca/EN/products-and-services/Pages/on-b...

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#115

Post by Retric »

nradov wrote: post #96
ClumsyPilot wrote: post #84

Earlier quoted context omitted.

Lasers were banned. Where does your certainty come from?

Lasers were not banned and are more heavily used now than ever before. Only blinding lasers were banned by treaty, and even with those China is semi-openly defying the ban.

“Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith.“

https://news.ycombinator.com/newsguidelines.html

It’s clear what they where referring to, as the argument was a type of drone being banned not all drones. Saying they “banned lasers” is correct even if they only banned a subset of lasers.

I am genuinely curious if you have a deeper argument. As small anti personnel drones seem suspiciously close to cluster munitions, but might be acceptable.

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#116

Post by baybal2 »

rtkwe wrote: post #94
ummonk wrote: post #61

Earlier quoted context omitted.

Yup, it seems to me that the optimal missile would use mid-course guidance before doing IR / visual light homing in the terminal phase.

All the stealth craft also included some IR avoidance as a matter of course, IR seeking missiles existed at the time these were designed. It's unclear if a more modern missile would still be sensitive enough to lock on and avoid chasing flares. The techniques they used to decrease the IR visibility are pretty neat. The engine nozzles are over the wings and there are a lot of airflow tricks used to cool it down faster…

Flares don't do much against anything besides mid and short wave infrared.

It's impossible to hide from long wave IR sensors, which detect the heat signature of the plane itself, and not its exhaust.

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#117

Post by baybal2 »

KingOfCoders wrote: post #25

I think the current anti stealth capabilities are not clear, countries that use anti stealth radar are not talking about the capabilities, e.g. what does "The superior stealth target tracking capabilities ensure optimal performance in demanding littoral environments." mean https://www.thalesgroup.com/en/netherlands/news/new-fire-con... or "Within this enormous range it detects a wide spectrum of targets: air breathin…

> "performance in demanding littoral environments"

This is a defence contractor 1337 sp33k for "Works well in the South China sea"

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#118

Post by phonebanshee »

nradov wrote: post #79
imtringued wrote: post #57

Earlier quoted context omitted.

Stealth bombers aren't going to dodge missiles. They need to reach their target before they are noticed at all. Otherwise the enemy will mount a response and intercept the bomber.

That is not realistic. In most circumstances the enemy won't have any defensive assets in the right place at the right time in order to generate an intercept. It's sort of like if you're deer hunting and spot one through binoculars a mile from you moving away. You're going to have to get really lucky to take that deer.

You're a member of the Deer Defense Corps, though, and this time you're much better armed than the hunter. You've also had twenty years of training for your mission. It's just that the hunter is really hard to see. You don't have to care about a hunter running away from you, that's not your job.

Given that there are very few B2s, they're only going to be sent against the most valuable and well protected targets. Those are the most likely to have very alert defensive assets in exactly the right place to go after the B2s.

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#119

Post by nradov »

Retric wrote: post #115
nradov wrote: post #96

Earlier quoted context omitted.

Lasers were not banned and are more heavily used now than ever before. Only blinding lasers were banned by treaty, and even with those China is semi-openly defying the ban.

“Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith.“ https://news.ycombinator.com/newsguidelines.html It’s clear what they where referring to, as the argument was a type of drone being banned not all drones. Saying they “banned lasers” is correct even if they only banned a subset of lasers. I am genuinely curious if you have a…

It was not even remotely clear what they were referring to. There are many different types of lasers.

Considering that the US, Russia, India, and China haven't even signed the Convention on Cluster Munitions there's clearly no political appetite for such bans among countries with large militaries. And such a ban would be unenforceable anyway because small drones are dual use technologies which don't require specialized manufacturing.

Re: Czech Passive Radar Detecting B-2 at 150 miles (2015)

#120

Post by sudosysgen »

nradov wrote: post #81
sfifs wrote: post #58

Earlier quoted context omitted.

If you can localize down to the range of a km? Can't you just shoot down optically? A giant dark plane blotting out the stars...

An airplane at altitude doesn't blot out stars. Optical sensors are nearly useless, especially against a black aircraft at night.

I doubt it. If people are able to photograph dark birds at night, I see no reason why a missile with much bigger optics and more efficient (wider band and monochrome) sensors wouldn't be able to find a plane.
Post reply on HN