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

Underwater ears everywhere

computer.rip

Post reply on HN
Print view View original

151–160 of 179 posts

Re: Underwater ears everywhere

#151

Post by bcbrown »

tommiegannert wrote: post #148
flacebo wrote: post #138

Earlier quoted context omitted.

When the company I work for was buying a brand new swiss grinding machine (which enables the manufacturing of some extremely precise parts), I had to fill and sign a very strange statement about: - the exact kind of goods that we will use the machine for - certify that we will not use it in any nuclear explosive activity, or unsafeguarded nuclear fuel-cycle activity, or the use of nuclear, chemical or biological weap…

Now I'm very curious what makes a precision grinding machine particularly useful for nuclear applications.

When you're using shaped charges to turn a large metal sphere into a small metal sphere, just about everything needs a high degree of precision.

Re: Underwater ears everywhere

#152

Post by Outright0133 »

tommiegannert wrote: post #148
flacebo wrote: post #138

Earlier quoted context omitted.

When the company I work for was buying a brand new swiss grinding machine (which enables the manufacturing of some extremely precise parts), I had to fill and sign a very strange statement about: - the exact kind of goods that we will use the machine for - certify that we will not use it in any nuclear explosive activity, or unsafeguarded nuclear fuel-cycle activity, or the use of nuclear, chemical or biological weap…

Now I'm very curious what makes a precision grinding machine particularly useful for nuclear applications.

Total layman guess: shaped nuclear charges?

No idea if that's even possible.

Re: Underwater ears everywhere

#153

Post by hgomersall »

Doxin wrote: post #89
stuff800 wrote: post #62

> Instead, the battle of submarine silence has mostly revolved around obscure technical problems of fluid dynamics, since one of the loudest noises made by submarines is the cavitation around the screw. Cavitation is loud, but usually only happens if they're running full out. What they're really listening for now are reactor plant noises. > I don't know if this is true today, but at least years ago the low-noise desi…

> What they're really listening for now are reactor plant noises. Which is why old timey diesel electric submarines still sometimes have the edge over modern subs. No plant noises at all if they are running silent. This leads to some hilarity in joint naval exercises every now and then. e.g. when HNLMS Walrus managed to "sink" among others the USS Theodore Roosevelt before getting away, to great consternation of the…

It's actually a good thing that allies are technically comparable. And this is surely the whole point of such exercises.

Re: Underwater ears everywhere

#154

Post by hgomersall »

XorNot wrote: post #53
tw04 wrote: post #31

Earlier quoted context omitted.

>I'm not sure why secrecy automatically means "conspiracy theory". It doesn't automatically, but literally everyone claiming the Navy was "hiding something" was going down the conspiracy theory route. I'm not talking about generalities, I'm talking about the specific situation in question which is the Titan sub. >the information is OK to release publicly from a security standpoint. What information are you referring…

Releasing the information 4 days later implies it took 4 days to properly process and categorize. It probably did take some time to properly process and categorize it, because anomalous sounds happen underwater all the time, and unless it's a subsea nuclear detonation or a Russian propeller screw then it's going to go into the "figure it out later" bucket. So what we know is it took no more then 4 days to categorize…

This seems most plausible. The whole thing has an air of being carefully stage managed. Lots of showing off of general capability without much detail. Lots of international cooperation noise. Etc etc. It feels like the audience was not the general public, but I'm sure a bit of general distraction from other stuff happening didn't hurt.

Re: Underwater ears everywhere

#155

Post by autokad »

efitz wrote: post #109

> It is unwise, in the course of a search and rescue operation, to report that you think the vessel was irrecoverably lost. I made this point several times on social media during the Titan incident but it fell on deaf ears; it seemed crazy to me that people were accusing the US Navy of some nefarious cover-up regarding possible acoustic detection of implosion. Anyone who’s ever worked with any type of signal analysis…

I'd rather the Navy be pretty sure they were dead and tell me, instead of keeping it to themselves just because they might be wrong. No one was saying don't look, people were annoyed they pretended they knew nothing when they where 99% sure the sub imploded.

Re: Underwater ears everywhere

#156

Post by thomashabets2 »

lesuorac wrote: post #142
MarkusWandel wrote: post #126

Ever since that MH370 plane disappeared, I've been wondering. Would it going into the water make a splash that is audibly significant (compared to other surface noise i.e. waves) and would there be hydrophones in that area of the ocean, and would enough signal processing perhaps be able to locate the splash? And has all this perhaps already been done, but the people who have, can't talk about it?

It took them many days to find the Titan despite exact knowledge of where the Titanic is. MH370 could be in a significantly wider area of the ocean so it's going to be much harder to find it. Although prices of it have already been found [1] and used to determine a crash location (35.6°S 92.8°E). [1]: https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370#M...

Per the article it took them 5h to find it, after they got a vessel to the site. Not days.

They seem to have gone right to it just about immediately.

Re: Underwater ears everywhere

#157

Post by aidenn0 »

AlbertCory wrote: post #85

A question about ELF and VLF for whoever knows: I just finished reading Thunderstruck (Erik Larson, author of Devil in the White City ), which I don't recommend. It ineffectively juxtaposes the story of Marconi with Hawley Crippen, a murderer in London whose case became famous around 1910. (I say "ineffectively" because their stories really don't intersect, IMHO) The book goes on and on about all the demos and tests…

I think he was using MF and HF for most of his work, but I'm not sure[1]. The story about discovering higher frequencies remove the need for longer antennas lat in his career seems garbled since the he discovered early on that longer antennas allowed for longer distance communication.

1: His first claimed transatlantic transmissions were definitely MF.

Re: Underwater ears everywhere

#158

Post by lesuorac »

thomashabets2 wrote: post #156
lesuorac wrote: post #142

Earlier quoted context omitted.

It took them many days to find the Titan despite exact knowledge of where the Titanic is. MH370 could be in a significantly wider area of the ocean so it's going to be much harder to find it. Although prices of it have already been found [1] and used to determine a crash location (35.6°S 92.8°E). [1]: https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370#M...

Per the article it took them 5h to find it, after they got a vessel to the site. Not days. They seem to have gone right to it just about immediately.

Sticking with the article, it took them 1h to dive to the Titanic.

How much credit do you want to give the USN? As far as I'm concerned, the Titan was found at a expectable rate with a blind search given its proximity to the Titanic. The Titan was found 1600ft from the Titanic so a 1600^2 area (at 100 sq/ft s; The Odysseus has a 4k camera after all) would take 7 hours so finding it within 4 hours seems entirely plausible even if you just did a blind search starting from the Titanic. But also if you knew the exact location it wouldn't take you 4 hours to find it.

But my original point is really we already have estimates of MH370's location even without using secretive methods. It's just going to be a lot harder because knowing where on the surface it crashed doesn't tell you where it'll be below the surface.

Re: Underwater ears everywhere

#159

Post by thomashabets2 »

lesuorac wrote: post #158
thomashabets2 wrote: post #156

Earlier quoted context omitted.

Per the article it took them 5h to find it, after they got a vessel to the site. Not days. They seem to have gone right to it just about immediately.

Sticking with the article, it took them 1h to dive to the Titanic. How much credit do you want to give the USN? As far as I'm concerned, the Titan was found at a expectable rate with a blind search given its proximity to the Titanic. The Titan was found 1600ft from the Titanic so a 1600^2 area (at 100 sq/ft s; The Odysseus has a 4k camera after all) would take 7 hours so finding it within 4 hours seems entirely plaus…

Checking near the Titanic seems like the obvious choice. Whether or not USN microphones helped much, I of course don't know.

But my point is that it was not the case that even with USN help it took them days to find it, implying USN could not locate it in less. It's simply not information one way or the other, on its own. This data is consistent with both them instantly knowing exactly when and where, and taking days.

I'd believe it can take hours to check a small area, taking care to not drift into anything, and aiming powerful narrow spotlights. Oh, and avoiding getting currents to smack you into something of a historic landmark.

Especially since the implosion had the power of some hundreds of kg of TNT, and parts can move around in the streams too, over the past days.

Re: Underwater ears everywhere

#160

Post by AlbertCory »

aidenn0 wrote: post #157
AlbertCory wrote: post #85

A question about ELF and VLF for whoever knows: I just finished reading Thunderstruck (Erik Larson, author of Devil in the White City ), which I don't recommend. It ineffectively juxtaposes the story of Marconi with Hawley Crippen, a murderer in London whose case became famous around 1910. (I say "ineffectively" because their stories really don't intersect, IMHO) The book goes on and on about all the demos and tests…

I think he was using MF and HF for most of his work, but I'm not sure[1]. The story about discovering higher frequencies remove the need for longer antennas lat in his career seems garbled since the he discovered early on that longer antennas allowed for longer distance communication. 1: His first claimed transatlantic transmissions were definitely MF.

Wikipedia says he was using "pulses" instead of "continuous wave" which we now use. So maybe the question about "frequency" doesn't even apply? idk
Post reply on HN