News for hackers. Stuff that matters.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by giantg2 on Saturday May 14, 2022 @05:42PM (#31382858)
If you're going to play around with explosives, an old knowledgeable teacher is best. I imagine incompetence gets weeded out early. The guy in the video has been in quite a few others too. It's fun to see how the hosts are usually a little nervous and he's calm as can be.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by dvtrn on Saturday May 14, 2022 @06:26PM (#31383271)
"What makes me a good Demoman? Well if I were a bad Demoman, I wouldn't be sitting here discussing it with you, now would I?"

One of the silliest, hilarious but on point thing I've ever heard uttered from a video game character

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by ethbr0 on Saturday May 14, 2022 @08:12PM (#31383997)
"Hey look, buddy. I'm an engineer: that means I solve problems.

Not problems like 'What is beauty?' Because that would fall without the purview of your condundrums of philosophy.

I solve practical problems..." https://m.youtube.com/watch?v=SNgNBsCI4EA

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by jimnotgym on Sunday May 15, 2022 @05:02AM (#31386285)
It strikes me that if you work with modern explosives and follow sensible procedures like retiring to a safe distance, the risks to you are not that high. The risks in a demolition are huge, but not to the life of the explosives guy. I can imagine the job of weakening the structure, (by removing parts of it) prior to the explosives carry more risk to the operator
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by mensetmanusman on Sunday May 15, 2022 @07:34AM (#31386912)
I don’t know. I’m a trained chemist and after enough years, you have that one day where you might’ve went to sleep too late and where you use the wrong type of glass, and a boiling vat of sulfuric acid etc. fails quickly and melts a bunch of stuff.

Sometimes I’m glad I’m in this field though, because I hear about the researchers working on prions that have started dying off, and I know it’s one of those one and 100,000 events that you inevitably experience.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by giantg2 on Sunday May 15, 2022 @08:51PM (#31392697)
What's this about the prion researchers? I only know about the one lady (from France?) who caught it after puncturing her glove. If I remember correctly she didn't follow the proper protocols afterwards (although it's debatable if they would have made a difference).
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by yencabulator on Tuesday May 17, 2022 @12:59PM (#31413471)
If you screw it up, you end with a non-exploded thing that you have to tear down. That's where the risk is.

Plastic explosive with electric igniter ain't that bad, but old school fuses and mines are scary.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by matheusmoreira on Saturday May 14, 2022 @08:39PM (#31384171)
The bad demomen had to be glued back together. In hell.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by bawolff on Saturday May 14, 2022 @08:30PM (#31384115)
Survivorship bias personified
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by sophacles on Saturday May 14, 2022 @09:32PM (#31384452)
But... in a field where being bad at your job is fatal, is it really a fallacy?

Serious question - just like quoting an expert in the relevant topic isn't an appeal to authority, etc.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by bawolff on Saturday May 14, 2022 @09:52PM (#31384560)
Its still a fallacy because some people are just lucky instead of being skilled, and its entirely possible to confuse the two.

In the same way, an appeal to an authority is better than nothing, but its still a really weak argument. You can misunderstand authorities and authority can be mistaken or suborned. Its a reasonable argument if nobody knows much about the topic, but its never convincing if people are learned in the topic; the benefit of an expert is not that they are experts, its that they know how to defend their position with reasoning. As the motto of the royal society says "Nullius in verba".

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by daxfohl on Saturday May 14, 2022 @11:16PM (#31384963)
Survivorship bias is more about believing a task is safe/easy because you only hear from the survivors/winners. Not about saying someone is better at a job because they haven't died/lost yet.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by zhengyi13 on Saturday May 14, 2022 @10:02PM (#31384597)
Luck eventually runs out. That's not to say you're wrong, only that I expect the distribution of the lucky amongst the skilled tends towards zero over sufficient time.

"Beware old men in a young man's game."

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by Retric on Saturday May 14, 2022 @10:23PM (#31384710)
Depends on how often you role the dice not just how bad the dice are. Someone that’s got a 1% chance of dying every fireworks show is extraordinarily bad at their job. But if they only put on 2 shows a year they have better than even odds of surviving a 40 year career.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by somenameforme on Sunday May 15, 2022 @01:13AM (#31385423)
The odds there are surprisingly high, but not better than even. 44.75%
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by GreymanTheGrey on Sunday May 15, 2022 @01:43AM (#31385514)
Actually the OP is correct - the odds of dying are 44.75%, while the odds of surviving are the corollary of 55.25%, i.e. greater than even.

Edit: Nope I'm wrong, just redid the math. Apologies.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by bawolff on Sunday May 15, 2022 @02:55AM (#31385756)
But the important odds in this situation is not the individual, but the group - if you start with a group of 100 (or whatever) people extraordinarily bad at their job, what is the probability at least 1 makes it 40 years.

Survivorship bias is a bias because the sample is biased - Its when you pick a group of people who have already won and then are surprised that they beat the odds and won because you confuse the probability that a specific person wins with the probability that at least 1 person wins.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by dmurray on Sunday May 15, 2022 @07:57AM (#31387024)
Actually, the important odds are: given that you've met a 75-year old explosives professional, how likely is it that he was skilful instead of lucky?

To get a good estimate of this you need to come up with some priors about how many skilful and unskillful equivalents there were at the age of 30 and how much worse the unskillful ones are at staying alive.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by Retric on Sunday May 15, 2022 @06:38AM (#31386669)
It was a survivorship bias point but I didn’t make that clear.

I meant if you meet X people at a random point in their career then on average more than half will make it to the end because some of the original sample died before you sampled the population. Basically older people would have a lower chance of their luck running out even if they where all equally incompetent.

At least assuming the original population isn’t dying of something else vastly more often etc.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by bawolff on Saturday May 14, 2022 @11:16PM (#31384959)
The real question is what amount of time is sufficient. Its probably longer than you expect.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by panqueque on Sunday May 15, 2022 @03:08AM (#31385799)
> just like quoting an expert in the relevant topic isn't an appeal to authority, etc.

The credentials of the expert don't determine whether or not the statement is an appeal to authority.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by mhh__ on Saturday May 14, 2022 @07:59PM (#31383919)
The younger guy in this clip actually ended up retiring because he got brain damage in a contraption he designed for this show.

https://www.bbc.com/news/uk-58762935

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by matheusmoreira on Saturday May 14, 2022 @08:34PM (#31384141)
> The injuries happened when Mr Stansfield, who was 42 at the time, filmed a Bang Goes The Theory feature about the relative safety of forward and rear-facing child car seats.

> The episode saw him "strapped into a rig like a go-cart which was propelled along a track into a post".

I'm sorry but to me this reads like something out of Darwin Awards.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by htk on Saturday May 14, 2022 @09:35PM (#31384466)
That’s why he was awarded around half of what he demanded, because BBC shared the responsibility by accepting the stunt, but he was also responsible for doing it.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by robocat on Saturday May 14, 2022 @10:11PM (#31384651)
> That’s why he was awarded around half of what he demanded

Which is why he asked for 4x what might be fair? I’m being facetious: I have no idea. I am just saying there is little constraint on how much damages you can reasonably ask for.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by supernova87a on Saturday May 14, 2022 @11:15PM (#31384955)
Doesn't the BBC contract out to production companies so that they're not liable as a huge organization for one small show's dumb actions? Seems odd, but maybe that's not a thing in the UK.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by londons_explore on Sunday May 15, 2022 @03:07AM (#31385797)
UK courts generally see through such things.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by kepler1 on Sunday May 15, 2022 @04:07AM (#31386066)
See through some things, but not through others? How about hiding billions of pounds worth of corrupt money in London real estate? Not so much.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by megapolitics on Sunday May 15, 2022 @04:19AM (#31386109)
That’s more of a problem of a lack of cases brought by the government than a problem with the courts. The courts have generally seen through such things quite well when the government actually brings forward cases.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by stjohnswarts on Saturday May 14, 2022 @08:47PM (#31384214)
Exactly, this is what dummies (the inanimate ones), cameras, and sensors are for O_O
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by itsyaboi on Saturday May 14, 2022 @08:07PM (#31383974)
This is bizarre. He knowingly, purposefully took the place of a crash test dummy? Why?
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by sacrosancty on Saturday May 14, 2022 @10:48PM (#31384838)
Apparently they used to do that. Here are people demonstrating the safety of seatbelts by crashing their car https://www.youtube.com/watch?v=GWy0hHHECdM
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by kayodelycaon on Saturday May 14, 2022 @10:47PM (#31384830)
I assume he was focused on doing the experiment he (and dozens of other people) lost sight of the consequences.

As we say in America: “Hold my beer.”

Edit: Or more charitably, they underestimated the consequences.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by noneeeed on Sunday May 15, 2022 @03:51AM (#31386000)
Pretty much the latter.

This wasn’t Jackass, it was a science programme and he was the resident engineer. In theory he knew what he was doing but underestimated the risks and paid the personal consequences.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by green-eclipse on Saturday May 14, 2022 @11:14PM (#31384951)
"Hi, I'm Johnny Knoxville and this is crash test humans"
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by h2odragon on Saturday May 14, 2022 @06:11PM (#31383134)
Count the fingers. More than 8 is probably OK. age may be a drawback, one gets too old to meddle with some of the more fun things eventually.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by IncRnd on Saturday May 14, 2022 @08:12PM (#31383998)
There are old people who use explosives. There are bold people who use explosives. But, there are no old, bold people who use explosives.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by ethbr0 on Saturday May 14, 2022 @08:25PM (#31384078)
Reading Ignition! convinced me that there's more than raw intelligence to experimenting with energetic chemistry. https://www.amazon.com/gp/aw/d/0813595835/
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by function_seven on Saturday May 14, 2022 @09:56PM (#31384578)
Note to anyone that might be tempted to get this as an audiobook: Don't!

It didn't occur to me that the subject matter would be incompatible with narration, but it (IMO) just doesn't work that way. Large portions of the book have equations and heavy notation. Here's an actual passage:

> it can be simplified to cee equals bracket two aitch over em end-bracket to the one half power times bracket one minus parentheses pee e over pee cee end parentheses to the ar over cee pee power end bracket to the one half power.

Yeah, I just couldn't keep listening to that. I need to get a print copy, because the subject matter is interesting.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by PebblesRox on Sunday May 15, 2022 @10:42AM (#31387847)
Reminds me of a family story about my aunt recounting a Feynman lecture to her kids. She was drawing some diagrams he'd used and they said, "Wait a minute, how do you know what these looked like? Weren't you just listening to the audio?"

She realized that Feynman's verbal explanations were so clear that she had not had any trouble visualizing the diagrams as he drew and discussed them.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by kbelder on Monday May 16, 2022 @04:35PM (#31402848)
My Dad: "Hey, put that dynamite back down!"

It was just in a box in the back of his truck. Looked fun.

I wince, sometimes, thinking back. But my family was a logging family, so getting blown up was just one in a long list of ways to die.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by fortran77 on Saturday May 14, 2022 @07:47PM (#31383838)
And he still has 10 fingers! Unlike, for example, Mark Pauline (https://en.wikipedia.org/wiki/Mark_Pauline)
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by swayvil on Saturday May 14, 2022 @08:00PM (#31383924)
A bit of a nervous twitch perhaps.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by relbeek2 on Saturday May 14, 2022 @10:45PM (#31384816)
The calmness comes from really knowing and understanding what you are working with. I used to frequently work around hundreds of thousands of pounds of class 1 explosives. Once you understand that the primary risks of dry explosives are impact, shock, and impingement. You can protect yourself against those risks and get comfortable working around the material.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by Vladimof on Saturday May 14, 2022 @05:52PM (#31382969)
This type of explosive is very stable... nothing like nitroglycerin ...
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by giantg2 on Saturday May 14, 2022 @06:07PM (#31383097)
The explosive is stable (small cubes of most plastic explosive can even be lit on fire and act as fuel). But there is still danger in correctly handling/connecting the detonator. I'm not sure, but I thing the acceleration charge might be a less stable type as well (obviously they aren't going to give us step by step instructions).
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by Vladimof on Saturday May 14, 2022 @06:23PM (#31383242)
> (obviously they aren't going to give us step by step instructions).

nitrocellulose is very simple to make and detonate... and is also very stable.... I don't see why we need secrets... I played with that stuff when I was a teenager

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by aurizon on Saturday May 14, 2022 @09:19PM (#31384379)
When I was in college in Toronto in 1961 there was a surplus store. All manner of WW2 radios etc. I looked at one pile and it was about 15 rolls of primacord. This was a long 5/16 hollow tube of vinyl filled with pure TNT. It resembled rope = rope pile/ $3/roll of 100 feet. 2/$5. I knew what it was, so bought it all. it being worth $25-30/roll/ I was an Engineering stoont and Russia had just set of their Czar bomba. We engineers had a group called the BFC(Brute Force Committee), so we had to have a bomb for Skule Nite. In the quad we set off about a quarter pound of this prima cord with a lighted fuse detonator. We paced off a 100 meter circle for crowd control and Mr Riggs set it off. Prima cord has a hugely fast rate of propagation of the detonation wave, so we heard an intense CRACK, not a boom with a few tens of milliseconds, but a true faster than sound detonation wave. No harm was done as had just set of the Skule cannon which alerted people to cover their ears. I explored these rolls with playing with the Monroe effect, A nice shapely rabbit hole. https://en.wikipedia.org/wiki/Shaped_charge

I stamped initials in steel beams etc. Hardest thing was getting detonators = well controlled. Never tried to make a tank buster.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by aurizon on Sunday May 15, 2022 @03:06PM (#31390072)
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by jacquesm on Sunday May 15, 2022 @08:21AM (#31387122)
Active surplus?
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by aurizon on Sunday May 15, 2022 @09:53AM (#31387567)
Hercules Sales = sold Surplus on Yonge at Wellesley. The strip around there had Electro Sonic, Radio Trade Supply, Paramount Equipment and 2-3 small surplus and parts sellers. When transistor came along, radios never broke, TV's never broke and the parts and surplus ecosystem went away. Efrem Kohn came from Israel in the mid 60's and his Uncle Frank and Peter Eben who owned Active Machinery gave Efrem(Freddie) one of their store fronts = Active Surplus. He carried on until Queen W got gentrified and electronics from Taiwan and later China totally swamped Canadian electronics = all died off = no more surplus. The surface mount assembly also made parts salvage by hobbyists a waste for most people. Now there are only Creatron and one other place on College. I had 7 stores in 1985, closed the last in 2002. I was Parts Galore, a few remember me at trade shows, but I went into mining in 1995 and sold my company in 2018 and retired.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by jacquesm on Sunday May 15, 2022 @10:07AM (#31387646)
Super interesting, thank you for the backstory. I lived in Toronto from 1998 to 2003 and spent quite a bit time roaming around the dustier parts of AS.

Fond memories!

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by aurizon on Sunday May 15, 2022 @10:19AM (#31387712)
Yes, thanks. The Toronto surplus area was minuscule compared to Canal STreet in New York city in the 50's and low 60's. You might find some rabbit holes on google of the old days?.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by MertsA on Monday May 16, 2022 @10:40AM (#31398072)
nitrocellulose isn't necessarily very stable. If it's an amateur making gun cotton there's always the risk that they won't properly wash out the acid and if there's enough left, when left to dry the evaporation of the water can concentrate the remaining acid enough to cause spontaneous combustion. Other than that it's pretty stable but worth pointing out that film used to use nitrocellulose as the base material and there's tons of movie theatres that burned down in those days and even just vaults storing the film under ambient conditions. As the nitrocellulose decays, it can release nitric acid, thus accelerating the decay and potentially starting a fire.

If properly prepared and used and stored responsibly then gun cotton can be safe, even when used for teenage antics. Lighting off a piece while resting it on an open palm of course being one classic trick with nitrocellulose. I'd say storage and transportation of low and high explosives are some of the riskiest aspects because there's so many insidious ways for it to go wrong that you wouldn't learn about until you need to take your shoes off to count past 7. It doesn't help that nowadays it's so trivial to find out how to synthesize acetone peroxide and storing it long term is always going to be fraught with peril. Especially when someone without any semblance of proper containers stores it sealed up in a plastic bottle with a screw on cap. Just one drop or one crumb of primary explosive on the screw threads and maybe you get it sealed up, but when it dries out in the threads there's a good chance it goes off in your closed up hand when you try to open it and add in all the friction rubbing between the threads.

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by ILMostro7 on Saturday May 14, 2022 @08:11PM (#31383990)
I assume it helps to narrow down the list of suspects if/when the (guarded/secret) knowledge is used for nefarious purposes.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by chemeril on Saturday May 14, 2022 @09:08PM (#31384314)
Nitrocellulose is not a high-order explosive and used nowhere in this experiment. Deflagration != detonation.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by giantg2 on Saturday May 14, 2022 @06:27PM (#31383275)
Is that what they are using for the acceleration charge (not the main charge!)?
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by chemeril on Saturday May 14, 2022 @09:17PM (#31384372)
It is not. Nitroglycerin doesn't have the capacity to detonate (necessary for triggering the main charge). Detonators (the acceleration charge you mention) are usually an explosive train starting with a sensitive primary like lead azide moving up to a secondary or pseudosecondary output charge like PETN.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by lazide on Saturday May 14, 2022 @10:20PM (#31384699)
Oh man lol. Nitroglycerin most certainly has the power to initiate even a insensitive explosive like RDX, PETN, etc. It's detonation velocity is ~ 7700m/s. It's just very unstable which is why it isn't used raw. A jostle or turning the stopper on the bottle it's in can set it off. The less pure it is, the more dangerous it is. It's detonation velocity is twice as high as lead azide for instance.

Nitrocellulose can also be detonated with a properly brisant primary charge, which nitroglycerin is quite capable of being.

Typically Nitrocellulose (aka gun cotton, and the primary ingredient in most smokeless powders) won't detonate on it's own, but it's a very different beast from nitroglycerin.

[https://en.wikipedia.org/wiki/Table_of_explosive_detonation_...]

Re:Shaped Charges – Sheet of copper going through 1ft of sol... by chemeril on Saturday May 14, 2022 @10:46PM (#31384829)
GP's comment was referencing nitrocellulose, which is what I was attempting to address but fatfingered to 'nitroglycerin'. Forgive the typo.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by giantg2 on Sunday May 15, 2022 @07:09AM (#31386797)
The diagram shows a detonator and an acceleration charge. That's why I was wondering what the acceleration charge was.
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by jwhitlark on Sunday May 15, 2022 @10:36AM (#31387809)
They used to burn c4 in Vietnam to heat coffee/food. Just don't step on it, as it suddenly remembers it's an explosive...
Re:Shaped Charges – Sheet of copper going through 1ft of sol... by trasz on Sunday May 15, 2022 @01:13PM (#31389009)
>obviously they aren't going to give us step by step instructions

It’s thoroughly explained in the manuals freely available at US Army web site.