Analysis of the Beirut explosion?!

[sevenperforce]

17 minutes ago, mikegarrison said:

We are miscommunicating. I did not mean multiple dets into one explosive charge. (Although, the idea of a backup does seem like a good idea.) I meant when there are multiple charges. They typically don't just hope for sympathetic detonation, but rather arrange so that each charge happens in sequence or simultaneously (as needed). Like when imploding buildings or blowing rock apart.

Yeah we were just crossing communication.

I was responding to @kerbiloid, who was insisting that a single pile of high explosive needed multiple detonators and structural containment to avoid the explosive being blown apart before it could fully detonate.

[Guest]

14 minutes ago, kerbiloid said:

I have nothing to add to the said earlier, and definitely I don't think that this is a proper forum for moar info on this topic.

It is a proper forum for scientific matters, not just spaceflight. Explosives are science, and this is a place people can learn about them, just like about anything else. In particular, you'd do well to learn from it. You could learn a lot about how explosives work and are handled from this discussion. We took effort to straighten out every single one of your misconceptions. You should be glad we did, because now you have not only information, but several links to sources about it, from actually knowledgeable people.

Or you can ignore it and make our lives difficult by spreading misconceptions and mocking those who try to teach others something useful. But that wouldn't be very nice.

[sevenperforce]

29 minutes ago, Dragon01 said:

It is a proper forum for scientific matters, not just spaceflight. Explosives are science, and this is a place people can learn about them, just like about anything else. In particular, you'd do well to learn from it. You could learn a lot about how explosives work and are handled from this discussion. We took effort to straighten out every single one of your misconceptions. You should be glad we did, because now you have not only information, but several links to sources about it, from actually knowledgeable people.

Aye.

I will point out that this forum likely has as much aggregated scientific and engineering knowledge as any gaming forum out there. KSP attracts a certain type of person.

I learn new stuff here all the time.

[K^2]

14 minutes ago, Dragon01 said:

Or you can ignore it and make our lives difficult by spreading misconceptions and mocking those who try to teach others something useful. But that wouldn't be very nice.

One of the nicer things about science is that given a bit of a back-and-forward and time, people who understand how it works will always weed out these who don't. Even if you aren't an expert in a field, you can identify another who is. When a topic comes up that doesn't have a local expert, consensus is usually established on what is plausible. So long term, this really isn't a problem. When I see someone like @sevenperforce make an estimate, I know where it's coming from, and if we disagree on the numbers, we'll work it out within a few posts, and one of us will realize a mistake and have something that's at least on the same order of magnitude by the end. By the same token, I know who isn't capable of critical analysis of own work, and the only reason to reply is to signal to others that this is total nonsense.

But this is also a forum where a lot of people with scientific curiosity, and not an actual expertise come, and in these cases a bad actor can be a problem. This is why we have forum rules against posting conspiracy theories. Unfortunately, that's not adequate for pet conspiracy theories, as they are much harder to identify from perspective of effective moderation. When somebody comes around with "novel" (but also proven false by decade-old experiments) ideas on Quantum Mechanics for example, as has happened in the pass, it's hard to explain to moderation team why that has the same place in scientific community as homeopathy. And in this case, all you really can do is make sure bad actors are well known, and community overall is able to provide good answers or clarifications when needed.

[kerbiloid]

34 minutes ago, Dragon01 said:

It is a proper forum for scientific matters, not just spaceflight.

You won't build an antimatter starship in your shed.

I don't want to get into technical details of explosions.

Edited August 10, 2020 by kerbiloid

[sevenperforce]

7 minutes ago, K^2 said:

One of the nicer things about science is that given a bit of a back-and-forward and time, people who understand how it works will always weed out these who don't. Even if you aren't an expert in a field, you can identify another who is.

That's why "show the maths" is so important.

7 minutes ago, kerbiloid said:

You won't build an antimatter starship in your shed.

I should hope not.

7 minutes ago, kerbiloid said:

I don't want to get into technical details of explosions.

You seemed very intent on getting into the technical details of explosions before. "too porous" and all.

Just saying.

[Guest]

16 minutes ago, kerbiloid said:

You won't build an antimatter starship in your shed.

I don't want to get into technical details of explosions.

Don't worry, with your information, nobody is going to do any damage.  Besides, we're not discussing how to actually make a working bomb. Besides, knowing those fine details gets one no closer to making a bomb than the knowledge that fireworks and AN don't mix.

If you're intentionally spreading misinformation in order to deter potential terrorists, you should indicate this somehow, because so far, each of your statements only resulted in the correct explanation being posted in reply (often sourced, at that). 

[sevenperforce]

Looks like there is additional info -- the stuff in the Beirut warehouse wasn't fertilizer-grade ammonium nitrate (FGAN), but rather technical grade, security sensitive ammonium nitrate (TGAN/SSAN), a finely powdered form of AN specifically designed for use as an ANFO precursor for mining explosives. Particle size is smaller and more uniform in order to make it absorb fuel oil more readily. This would make it more likely to absorb any VOCs or aerosolized hydrocarbons, as well as making it more likely to explode uniformly and completely.

[Guest]

Ouch. And someone put fireworks next to that? TGAN is not only finely powdered, but would also have a much lower water content, making it very definitely an explosive (well, duh, that's what it's for). FGAN runs the gamut and is usually quite benign (people got away with using dynamite sticks to break it up for quite some time), but SSAN is another story. Now, I suppose it's possible that it was listed as "explosives warehouse" in the permits, so from bureaucratic point of view, everything was fine. They're usually not that detached from reality on safety-critical matters, but it does happen. 

TBH, I think there should be some sort of international law giving certain people authority to bypass the normal court process in order to deal with abandoned hazardous materials. It's not the first time a disaster happened when the entity responsible went bankrupt and people were haggling over the assets in court. Indeed, everyone who knew about it could see it coming (there were several warnings from inspectors), but nobody had the legal ability to just get rid of the stuff. Few people have the guts to ignore the law for the common good, or go public and hope the resulting ruckus forces the government to take action right now.

[kerbiloid]

1 hour ago, sevenperforce said:

That's why "show the maths" is so important.

This is exactly what I see not appropriate.

***

Also I'm just bored reading the nonsense from people who even don't read what I write.

[Guest]

43 minutes ago, kerbiloid said:

This is exactly what I see not appropriate.

It is appropriate, because we've all done (and shown) the same maths. They would not allow anyone to make a bomb. They would, however, trivially show why you're wrong. "Evidence exists, but I won't show it, because reasons". That's what you always fall back on when you run out of nonsense, and most people can easily see through that. Admitting that you're wrong (first to yourself, then maybe to others) doesn't make you look like a fool nearly as much.

Everything you've said has been refuted by people with actual scientific degrees (yes, we did read what you said. We also presented valid counterarguments that you never addressed). Your estimation has been refuted by actual explosive experts speaking on the matter. If you still refuse to believe you're wrong after that, we have to play poker someday.  

Edited August 10, 2020 by Guest

[kerbiloid]

You presented nothing except misunderstanding basics. Also you presented no math at all.

Maybe space fighters with tungstenn-lithium armor would be a nice alternative for this.

I don't care about someone's scientific degrees.

Edited August 10, 2020 by kerbiloid

[sevenperforce]

1 hour ago, Dragon01 said:

And someone put fireworks next to that? TGAN is not only finely powdered, but would also have a much lower water content, making it very definitely an explosive (well, duh, that's what it's for). FGAN runs the gamut and is usually quite benign (people got away with using dynamite sticks to break it up for quite some time), but SSAN is another story.

Here's one of the sources -- looks like it was ordered by an explosives manufacturing company that supplied HE for mining operations in Mozambique. The shipment never made it there, obviously. But that definitely strengthens the idea that it was TGAN/SSAN, not just FGAN.

Sadly it looks like there were many attempts to do something about it, including one plea sent by customs officials to the judge who purportedly ordered the impoundment of the cargo:

"In view of the serious danger of keeping these goods in the hangar in unsuitable climatic conditions, we reaffirm our request to please request the marine agency to re-export these goods immediately to preserve the safety of the port."

In contrast to certain people who keep insisting the blast was just a few dozen or perhaps a hundred tonnes TNT equivalent, note that the crater itself is 124 meters in diameter. My very first assessment of the blast at between 1 and 3 kiloton yield (within four hours of the blast and well before we heard anything about the amount of AN involved) was based on the instantaneous fireball size having a radius between 60 and 110 meters.

15 minutes ago, kerbiloid said:

You presented nothing except misunderstanding basics. Also you presented no math at all.

Right. I definitely didn't present the math allowing us to place the absolute lower bound on detonation velocity at Mach 7. And you definitely provide actual math as a rebuttal rather than just calling that an "emotional" figure. And we were definitely the ones "misunderstanding basics" because we stubbornly insist that high explosives produce hypersonic detonation waves. Basic misunderstandings, right?

Why is this important to you? Like, it's barely important to me, but I'm just curious.

Quote

I don't care about someone's scientific degrees.

Yes, we can tell.

Edited August 10, 2020 by sevenperforce

[kerbiloid]

6 minutes ago, sevenperforce said:

Why is this important to you? Like, it's barely important to me, but I'm just curious.

It's absolutely not important for me. I did this estimation just for fun, and all later posts were just a reaction on others' poking.
When they ask, I try to answer, that's all.
(All my posts were not a trolling or joking)

Obviously I don't think it's a good idea to turn the forum into another a-chist cook book with technical details and formulas.

Edited August 10, 2020 by kerbiloid

[sevenperforce]

4 minutes ago, kerbiloid said:

I don't think it's a good idea to turn the forum into another a-chist cook book with technical details and formulas.

Literally no one is going to build an explosive device using information about how to calculate the energy of an explosion.

You might as well worry that someone is going to cause a volcanic eruption based on a discussion of vulcanology.

[kerbiloid]

5 minutes ago, sevenperforce said:

Literally no one is going to build an explosive device using information about how to calculate the energy of an explosion.

You might as well worry that someone is going to cause a volcanic eruption based on a discussion of vulcanology.

I guess various formulas of detonator amount and distance are less appropriate than vulcanology.

So, as anyway I can't see here any traces of constructive discussion, the topic is offtopic.

Edited August 10, 2020 by kerbiloid

[Vanamonde]

Thread closed for a while to allow tempers to cool. 

[Vanamonde]

Thread re-opened. Play nice. 

[Guest]

On 8/10/2020 at 11:50 PM, kerbiloid said:

I guess various formulas of detonator amount and distance are less appropriate than vulcanology.

We were not asking for that, though. I suppose it could help us straighten out your idea that AN did not detonate completely, but here is a thing: high explosives are usually only provided with two or three detonators, and that is for redundancy. So the formulas you have are either for low explosives (which AN is not one of) or for the number and distance of charges (that is, separate pockets of explosive). If you post them, someone will tell you why they don't apply here.

Besides, when it comes to bombs, even Mk84s (which have around 400kg of high explosive) have just two fuses, and the one in the nose is turned off if penetration is desired. They still explode just fine. So these formulas would be useless for terrorists even if they did apply, because they don't make bombs that big. 

[kerbiloid]

2 hours ago, Dragon01 said:

We were not asking for that, though. I suppose it could help us straighten out your idea that AN did not detonate completely, but here is a thing: high explosives are usually only provided with two or three detonators, and that is for redundancy. So the formulas you have are either for low explosives (which AN is not one of) or for the number and distance of charges (that is, separate pockets of explosive). If you post them, someone will tell you why they don't apply here.

Neither of your presumptions is right.

[K^2]

Look, the only bit of math you provided is in this post here.

On 8/4/2020 at 1:01 PM, kerbiloid said:

Judging by the cabins on the top, the entrance, and the storey above the entrance,
and after measuring them in Inkscape (cabin ~=5.6 px, (entrance+2nd storey) ~= 20 px, building ~72 px),
taking cabin ~2- m, average storey ~3+ m
the building is ~8 storey, i.e. ~25 m.

Watching this a 1/16^x speed in VLC, we can clearly see that the fireball stops expanding at ~3.5 building heights diameter, 290 px, i.e. ~90 m.
Then the shockwave breaks away, while the fireball keeps calmly floating up and smoking.

It stops expanding because its internal pressure got equal to the outside.
So, total energy of its expansion is ~pV ~ 100 000 Pa * pi *90³ / 6 ~= 3.8*10¹⁰ J ~= 9 t TNT.

Together with shockwave, it's probably twice as great, i.e. ~18 t TNT.

Now, I didn't want to touch it, because I know how that discussion goes. But because you keep claiming that you've provided evidence in another thread, here it is in all its glory. I'm going to set aside for a moment the fact that the fireball radius estimate is off by a factor of two. I've hinted a number of times to you that you should go back and actually measure against the map, but even then you refused. That alone would inflate your estimate by a factor of 8, as volume increases as a cube - almost an order of magnitude. But that's not even the worst part. You are using an estimate used to evaluate sub-sonic explosions. Literally the only place I've found this used in practice is depth charges, but this might also work for early WWII munitions and older.

The core assumption is that fireball pressure is balanced against atmosphere. The problem with that is that there's a shock wave separating from the fireball, and there is gradient of pressure across any supersonic shock. That overpressure you kept mentioning? The one that goes into many times atmospheric pressure at fireball radius? That means your estimate of 1 bar is wrong by a factor of a few to lots depending on speed of supersonic wave. How do I know that there's a supersonic shock? Because I can measure buildings 500+ m away from the fireball that are reached within a second of shock wave separating from the fireball.

I know you'll try to jump in and come up with some sort of reason why 1 bar is the correct value to use. But there's a simple test. You know how critical thinking works? If you have a hypothesis, apply it to a situation you can verify. If I take 20kT explosion, say yield of Trinity Test so that we have lots of data on it, and then I do the same math on it. Your doubling was arbitrary, but lets do the same thing and half the yield that we count towards fireball expansion. So just 10kT, then compute corresponding radius, we get that fireball should stop expanding, according to your math, at R = (10kT * 4.2GJ/T * 3/(4pi) / 1bar) ^ (1/3) = 460m. Actual fireball at ~20kT yield is measured to be about half of that radius. So we just found another order of magnitude error in yield.

The actual physics of fireball expansion at supersonic speeds is that so long as the pressure is sufficient to keep accelerating shock wave, the fireball keeps growing. Once the pressure drops bellow that point, the shock separates. That pressure is rather high for a high speed shock. The specifics will vary from explosion to explosion. In case of a nuke, you can assume all energy is released pretty much at once for sake of simple math and use it as an estimate. Chemical explosions aren't as clean, and the fireball for the same yield will vary with the type of explosive due to that fact. This is why absolutely everyone has been using rate of expansion as a measurable and not the final size.

So you are using a completely the wrong model with completely the wrong input resulting in two orders of magnitude of error [snip]

Edited August 12, 2020 by Snark
Redacted by moderator

[kerbiloid]

[snip]

can't provide even simple well-known maths at all.

[snip]

Edited August 12, 2020 by Snark
Redacted by moderator

[K^2]

3 minutes ago, kerbiloid said:

can't provide even simple well-known maths at all.

I didn't need to. I cited it. I freely admit, I had to look it up, but the reason we had initial estimates in place before destruction or seismic data is Dimensional Analysis which has been famously used to get estimates in Trinity tests and applied all over the place. That's the SIMPLE and WELL KNOWN math. So go ahead and tell me why dimensional analysis is wrong here.

And again, your formula applied to Trinity Test provides a wrong answer. Please explain.

[kerbiloid]

[snip]

Better you explain what unexpected nuclear explosions were closing windows in your home, and where we can read more about this.

Edited August 12, 2020 by Snark
Redacted by moderator

[K^2]

[snip]

We are trying to do estimates of a physical quantity, namely yield of explosion in Beirut, using known methods. Dimensional Analysis is chief among these and resulted in early estimates. It has a big spread due to how sensitive the results are to measurements, but then we had more data and other methods were applied to refine the estimates. There is valuable discussion here about methods and results. Including bad estimates that result in errors, and that's fine. We sort through these and we try to figure out why these things don't work. That's scientific method. And this discussion is very valuable as an example of scientific method which is basis for this entire subforum. When I asked @sevenperforce where he got numbers I thought were suspect, it wasn't to make fun of him. It was a question in good faith. I took his equation, and I ran the math myself, and I found an inconsistency. Sometimes it goes another way. I follow someone's link, and I learn something new or discover a mistake in my own math. And that's valuable. This is why we're sitting here juggling numbers and estimates around instead of just talking about what a tragedy the explosion was. That's the whole point of having such a discussion, and it can only work when people act in good faith.

Edited August 12, 2020 by Snark
Redacted by moderator