11 ms·

This was while they were attempting to disarm the bomb using the technique of "slowly burning the explosive", which in my obviously completely inexpert opinion,

by hanoz 4y ago

This was while they were attempting to disarm the bomb using the technique of "slowly burning the explosive", which in my obviously completely inexpert opinion, I wouldn't have recommended.

kortex 4y ago
Some context as a chemist. Most explosives require DDT (deflagration to detonation transition) in order to explode. DDT occurs when the flame front goes supersonic in the material and creates a shockwave (simplification but close enough). Low sensitivity is desirable because you want explosives to go off on demand, not randomly. Thus, most bulk explosives can be safely burned without detonation. Primary explosives have a low DDT threshold, meaning it takes far less energy and/or confinement to DDT. Thus, you can have a small primary, sometimes a secondary booster, to set off your bulk charge. The primer can be removed/dissolved to render the weapon far safer. But not perfectly safe. I don't know the exact composition, but it is likely a combination of TNT, and one of the hexagen/MX explosives (RDX, HMX) [1]. Luftwaffe used Trialen 105 in their 250kg bomb [2], which is TNT, RDX, and aluminum powder, so lets go with that. TNT is fairly stable, *MX are quite stable, but picrates are ornery. Over time they can break down and react with metals in the casing. Metal picrates are much closer to primaries in temperament. They are also far more shock sensitive, which is why (somewhat paradoxically) it's safer to evac and burn these old bombs out, then to try to relocate it. There are other ways in which unstable residues can be formed, not just picrates (e.g. TNT can release NOx over time and form metal nitrate or fulminate salts). You also have all the impurities from synthesis (such as DNT and mixed nitrates). Over time this forms a witches' brew of mixed nitrates that's typically much more sensitive. Sensitive, as in, workers have died when their shovel struck the bomb casing. There would not even be time for the clunk sound to make it to their ears before obliteration. Or even just...nothing [4]. Hug your loved ones, folks. (side note: this is why if you ever find old orndance, or old bottles of certain chemicals e.g. ether, you should stop immediately and don't try to move it, just evacuate and call a hazmat team) What most likely happened is the old bomb corroded and formed a pocket of these unstable salts, and when the flame hit it, a DDT occurred which set off the bulk charge. This is all well known to ordnance disposal folks, hence the sandbox cover and evacuation radius. [3] Edit: tweaked wording after some more research into bomb composition. P.S. I updated my notes on explosive composition. Turns out WW2 US/UK favored picrate mixes far more than the Germans (who favored TNT, RDX, ammonium nitrate, and aluminum), and as a result, allied bombs from this period are much more unstable than German ones. Also note, forming unstable species isn't necessary for DDT: e.g. the Halifax and Beirut explosions were caused solely by burning ammonium nitrate. It's just much, much harder to get a pile of AN to go off than rando metal nitrate salts. [1] https://en.m.wikipedia.org/wiki/List_of_explosives_used_during_World_War_II https://en.m.wikipedia.org/wiki/List_of_explosives_used_duri... [2] https://en.m.wikipedia.org/wiki/SC250_bomb https://en.m.wikipedia.org/wiki/SC250_bomb [3] https://www.bbc.com/future/article/20150922-these-nazi-bombs-are-more-dangerous-now-than-ever-before https://www.bbc.com/future/article/20150922-these-nazi-bombs... [4] https://www.dw.com/en/wwii-bomb-self-detonates-in-german-field-leaves-crater/a-49331435 https://www.dw.com/en/wwii-bomb-self-detonates-in-german-fie...
- tradethedelta 4y ago
  > It's just much, much harder to get a pile of AN to go off Which is why Hezbollah is complicit in the Beirut port explosion of August 4, 2020. AN that's just sitting there for years doesn't simply explode for no reason.
  - mkl 4y ago
    There was a fire and the warehouse also contained a large amount of confiscated fireworks. Similar AN explosions have happened in several other countries too, with no resorting to conspiracy theories.
kayodelycaon 4y ago
Doesn’t seem all that nuts to me. C4 can be burned without it going bang.
- fbdab103 4y ago
  The rules must be different for 80+ year old explosives? Presumably every possible decomposition reaction is now present.
samus 4y ago
Some explosives, like C4, can actually be safely burned. To set them off, a detonator is required. Explosives from WW2 probably have similar properties, as it makes producing and handling huge warheads a much less dangerous activity. Of course, there might always be impurities in the material that makes them behave much more unstably, both from production and because of corrosion and chemical degradation over the ~80 years that have passed.
- NoZebra120vClip 4y ago
  [flagged]
mshockwave 4y ago
No I believe it's a common approach. Without the fuse dynamites are inert and you can burn it without exploding it, since they are actually flammable. Of course, lots of steps can go wrong like incomplete removal of the fuse.
grogenaut 4y ago
There's a lot about explosives and explosives removal that is not obvious. Even more so because those techniques are classified both to keep other weapon designers from designing around your diffusal methods, but also to keep from elevating the "game" as it were of the public. There's also a ton of stuff you don't learn until years later like how some old explosives cause salt crystals to form that mess everything up more. https://www.bbc.com/future/article/20150922-these-nazi-bombs-are-more-dangerous-now-than-ever-before https://www.bbc.com/future/article/20150922-these-nazi-bombs... What method would you have used in your common sense guess? The old cut the red wire method? Chat gpt says "call the police and leave the area" as the most effective bomb diffusal method. The experts then "diffuse the bomb" as the next step. So there you go.
- spoils19 4y ago
  [dead]
ranger207 4y ago
For safety while handling, many explosives need both heat and pressure to explode. Famously, soldiers in Vietnam would burn C4 for heating water. However, explosives tend to become more sensitive over time, and there's always a chance that the explosive filler in this bomb wasn't an insensitive explosive anyway. Given the chance of it exploding when burned versus exploding when jolted, it probably made sense to burn it in place
nine_k 4y ago
I would assume that the explosive was TNT. TNT actually takes some effort to detonate; this is why even artillery shells can be filled with it, an not explode during firing. TNT can also burn safely e.g if thrown into a fire in small amounts; you likely can even make a candle out of it. The bomb likely had another, undetected detonator which was triggered, and it produced enough of a shock wave to make the TNT explode.
- kortex 4y ago
  > The bomb likely had another, undetected detonator That would be really poor bomb design. Bombs are designed to be stored inert near the airstrip, mounted to staged aircraft and armed quickly by inserting a primer/detonator. There would be one and only one per bomb. The detonator would certainly be removed first before trying to burn out. Explosives usually become more unstable over time, sometimes forming pockets of primary explosives, which can detonate the bomb. See my sibling comment. Edit: I'm completely mistaken! Some bombs in fact have multiple fuse pockets, so presumably, multiple fuses. Nonetheless, even with all fuses removed, UXB can still go off during disposal.
  - chiph 4y ago
    The Germans would sometimes use a timed detonator on their bombs, intended to kill emergency services personnel who moved in after the raid and were fighting fires, aiding the wounded, etc. If you haven't seen it, the show "Danger UXB" from the early 80's is good. https://youtu.be/Mm-RQtPNvqY?t=268 https://youtu.be/Mm-RQtPNvqY?t=268
    - oneoff786 4y ago
      Those crafty Germans must have timed this one to go off in 2023.
      - chiph 4y ago
        After I clicked reply and went to do a chore I thought to myself "I didn't talk about how it's been almost 80 years and it's unlikely to have been a timer." Doh.
traceroute66 4y ago
> in my obviously completely inexpert opinion, I wouldn't have recommended I'm pretty confident they had some of the best experts on the case. The UK has some of the best bomb-disposal minds, the IRA campaigns on the mainland during The Troubles ensured that. Just look it up on wikipedia ... double-digit number of bombs planted in some years !
- goodSteveramos 4y ago
  Over a thousand or about 60% of the Provisional IRA kills were British soldiers. So yea they got hit hard. I haven't seen any evidence that they actually improved their bomb disposal techniques though. The British Army kept getting successfully bombed into the 90’s.
- twic 4y ago
  Does defusing a brand new IRA bomb involve the same set of skills as defusing a decades-old Luftwaffe one? I would have thought it's a rather different problem.
  - yarg 4y ago
    Not entirely. The IRA bombs are designed not to be disabled, whereas that's not a concern with a dropped bomb. With the older bombs degradation of the explosive needs to be considered.
- dsfyu404ed 4y ago
  IED has progressed immensely since the internet and the best bomb disposal techs are the people who'd been doing it recently and they're mostly in the middle east.
Philip-J-Fry 4y ago
Clearly the experts do recommend it in certain circumstances.
dannyphantom 4y ago
I'm reminded of the time I heard of the story of a US town blowing up a beached whale with TNT that didn't go as planned in high-school when we were on unit discussion the mechanisms of explosives. I think the teacher was there(?) as a kid and it...ignited...an interest in explosive engineering in him.
- blihp 4y ago
  While you possibly heard about a different story, this one has made the rounds over the years: https://www.youtube.com/watch?v=V6CLumsir34 https://www.youtube.com/watch?v=V6CLumsir34
fhars 4y ago
[flagged]
- nathanwh 4y ago
  I do agree that I see that comment a lot on here. However that seems to be a pretty uncharitable reading of the parent comment, as it seems they were more expressing surprise that burning the explosive is a legitimate means of defusing a bomb.
- Eisenstein 4y ago
  I think it was self-aware a joke referencing that very thing...
  - jonplackett 4y ago
    Whether it is or not, I would strongly recommend the OP - just like a striker who just scored a goal from a corner - immediately claim that is was 100% deliberate.
- zenexer 4y ago
  There’s nothing wrong with pointing out that a standard technique for disarming a bomb seems counterintuitive to a layperson. That’s the sort of observation that fuels curiosity and interesting discussion. I don’t think the OP was suggesting that it was the wrong technique.
- dang 4y ago
  "Please don't sneer, including at the rest of the community." It's reliably a marker of bad comments and worse threads. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
deleted 4y ago
[deleted]

by hanoz 4y ago

This was while they were attempting to disarm the bomb using the technique of "slowly burning the explosive", which in my obviously completely inexpert opinion, I wouldn't have recommended.

kortex 4y ago

Some context as a chemist. Most explosives require DDT (deflagration to detonation transition) in order to explode. DDT occurs when the flame front goes supersonic in the material and creates a shockwave (simplification but close enough). Low sensitivity is desirable because you want explosives to go off on demand, not randomly. Thus, most bulk explosives can be safely burned without detonation. Primary explosives have a low DDT threshold, meaning it takes far less energy and/or confinement to DDT. Thus, you can have a small primary, sometimes a secondary booster, to set off your bulk charge. The primer can be removed/dissolved to render the weapon far safer. But not perfectly safe. I don't know the exact composition, but it is likely a combination of TNT, and one of the hexagen/MX explosives (RDX, HMX) [1]. Luftwaffe used Trialen 105 in their 250kg bomb [2], which is TNT, RDX, and aluminum powder, so lets go with that. TNT is fairly stable, *MX are quite stable, but picrates are ornery. Over time they can break down and react with metals in the casing. Metal picrates are much closer to primaries in temperament. They are also far more shock sensitive, which is why (somewhat paradoxically) it's safer to evac and burn these old bombs out, then to try to relocate it. There are other ways in which unstable residues can be formed, not just picrates (e.g. TNT can release NOx over time and form metal nitrate or fulminate salts). You also have all the impurities from synthesis (such as DNT and mixed nitrates). Over time this forms a witches' brew of mixed nitrates that's typically much more sensitive. Sensitive, as in, workers have died when their shovel struck the bomb casing. There would not even be time for the clunk sound to make it to their ears before obliteration. Or even just...nothing [4]. Hug your loved ones, folks. (side note: this is why if you ever find old orndance, or old bottles of certain chemicals e.g. ether, you should stop immediately and don't try to move it, just evacuate and call a hazmat team) What most likely happened is the old bomb corroded and formed a pocket of these unstable salts, and when the flame hit it, a DDT occurred which set off the bulk charge. This is all well known to ordnance disposal folks, hence the sandbox cover and evacuation radius. [3] Edit: tweaked wording after some more research into bomb composition. P.S. I updated my notes on explosive composition. Turns out WW2 US/UK favored picrate mixes far more than the Germans (who favored TNT, RDX, ammonium nitrate, and aluminum), and as a result, allied bombs from this period are much more unstable than German ones. Also note, forming unstable species isn't necessary for DDT: e.g. the Halifax and Beirut explosions were caused solely by burning ammonium nitrate. It's just much, much harder to get a pile of AN to go off than rando metal nitrate salts. [1] https://en.m.wikipedia.org/wiki/List_of_explosives_used_during_World_War_II https://en.m.wikipedia.org/wiki/List_of_explosives_used_duri... [2] https://en.m.wikipedia.org/wiki/SC250_bomb https://en.m.wikipedia.org/wiki/SC250_bomb [3] https://www.bbc.com/future/article/20150922-these-nazi-bombs-are-more-dangerous-now-than-ever-before https://www.bbc.com/future/article/20150922-these-nazi-bombs... [4] https://www.dw.com/en/wwii-bomb-self-detonates-in-german-field-leaves-crater/a-49331435 https://www.dw.com/en/wwii-bomb-self-detonates-in-german-fie...

tradethedelta 4y ago
> It's just much, much harder to get a pile of AN to go off Which is why Hezbollah is complicit in the Beirut port explosion of August 4, 2020. AN that's just sitting there for years doesn't simply explode for no reason.
- mkl 4y ago
  There was a fire and the warehouse also contained a large amount of confiscated fireworks. Similar AN explosions have happened in several other countries too, with no resorting to conspiracy theories.

kayodelycaon 4y ago

Doesn’t seem all that nuts to me. C4 can be burned without it going bang.

fbdab103 4y ago
The rules must be different for 80+ year old explosives? Presumably every possible decomposition reaction is now present.

samus 4y ago

Some explosives, like C4, can actually be safely burned. To set them off, a detonator is required. Explosives from WW2 probably have similar properties, as it makes producing and handling huge warheads a much less dangerous activity. Of course, there might always be impurities in the material that makes them behave much more unstably, both from production and because of corrosion and chemical degradation over the ~80 years that have passed.

NoZebra120vClip 4y ago
[flagged]

mshockwave 4y ago

No I believe it's a common approach. Without the fuse dynamites are inert and you can burn it without exploding it, since they are actually flammable. Of course, lots of steps can go wrong like incomplete removal of the fuse.

grogenaut 4y ago

There's a lot about explosives and explosives removal that is not obvious. Even more so because those techniques are classified both to keep other weapon designers from designing around your diffusal methods, but also to keep from elevating the "game" as it were of the public. There's also a ton of stuff you don't learn until years later like how some old explosives cause salt crystals to form that mess everything up more. https://www.bbc.com/future/article/20150922-these-nazi-bombs-are-more-dangerous-now-than-ever-before https://www.bbc.com/future/article/20150922-these-nazi-bombs... What method would you have used in your common sense guess? The old cut the red wire method? Chat gpt says "call the police and leave the area" as the most effective bomb diffusal method. The experts then "diffuse the bomb" as the next step. So there you go.

spoils19 4y ago
[dead]

ranger207 4y ago

For safety while handling, many explosives need both heat and pressure to explode. Famously, soldiers in Vietnam would burn C4 for heating water. However, explosives tend to become more sensitive over time, and there's always a chance that the explosive filler in this bomb wasn't an insensitive explosive anyway. Given the chance of it exploding when burned versus exploding when jolted, it probably made sense to burn it in place

nine_k 4y ago

I would assume that the explosive was TNT. TNT actually takes some effort to detonate; this is why even artillery shells can be filled with it, an not explode during firing. TNT can also burn safely e.g if thrown into a fire in small amounts; you likely can even make a candle out of it. The bomb likely had another, undetected detonator which was triggered, and it produced enough of a shock wave to make the TNT explode.

kortex 4y ago
> The bomb likely had another, undetected detonator That would be really poor bomb design. Bombs are designed to be stored inert near the airstrip, mounted to staged aircraft and armed quickly by inserting a primer/detonator. There would be one and only one per bomb. The detonator would certainly be removed first before trying to burn out. Explosives usually become more unstable over time, sometimes forming pockets of primary explosives, which can detonate the bomb. See my sibling comment. Edit: I'm completely mistaken! Some bombs in fact have multiple fuse pockets, so presumably, multiple fuses. Nonetheless, even with all fuses removed, UXB can still go off during disposal.
- chiph 4y ago
  The Germans would sometimes use a timed detonator on their bombs, intended to kill emergency services personnel who moved in after the raid and were fighting fires, aiding the wounded, etc. If you haven't seen it, the show "Danger UXB" from the early 80's is good. https://youtu.be/Mm-RQtPNvqY?t=268 https://youtu.be/Mm-RQtPNvqY?t=268
  - oneoff786 4y ago
    Those crafty Germans must have timed this one to go off in 2023.
    - chiph 4y ago
      After I clicked reply and went to do a chore I thought to myself "I didn't talk about how it's been almost 80 years and it's unlikely to have been a timer." Doh.

traceroute66 4y ago

> in my obviously completely inexpert opinion, I wouldn't have recommended I'm pretty confident they had some of the best experts on the case. The UK has some of the best bomb-disposal minds, the IRA campaigns on the mainland during The Troubles ensured that. Just look it up on wikipedia ... double-digit number of bombs planted in some years !

goodSteveramos 4y ago
Over a thousand or about 60% of the Provisional IRA kills were British soldiers. So yea they got hit hard. I haven't seen any evidence that they actually improved their bomb disposal techniques though. The British Army kept getting successfully bombed into the 90’s.
twic 4y ago
Does defusing a brand new IRA bomb involve the same set of skills as defusing a decades-old Luftwaffe one? I would have thought it's a rather different problem.
- yarg 4y ago
  Not entirely. The IRA bombs are designed not to be disabled, whereas that's not a concern with a dropped bomb. With the older bombs degradation of the explosive needs to be considered.
dsfyu404ed 4y ago
IED has progressed immensely since the internet and the best bomb disposal techs are the people who'd been doing it recently and they're mostly in the middle east.

Philip-J-Fry 4y ago

Clearly the experts do recommend it in certain circumstances.

dannyphantom 4y ago

I'm reminded of the time I heard of the story of a US town blowing up a beached whale with TNT that didn't go as planned in high-school when we were on unit discussion the mechanisms of explosives. I think the teacher was there(?) as a kid and it...ignited...an interest in explosive engineering in him.

blihp 4y ago
While you possibly heard about a different story, this one has made the rounds over the years: https://www.youtube.com/watch?v=V6CLumsir34 https://www.youtube.com/watch?v=V6CLumsir34

fhars 4y ago

[flagged]

nathanwh 4y ago
I do agree that I see that comment a lot on here. However that seems to be a pretty uncharitable reading of the parent comment, as it seems they were more expressing surprise that burning the explosive is a legitimate means of defusing a bomb.
Eisenstein 4y ago
I think it was self-aware a joke referencing that very thing...
- jonplackett 4y ago
  Whether it is or not, I would strongly recommend the OP - just like a striker who just scored a goal from a corner - immediately claim that is was 100% deliberate.
zenexer 4y ago
There’s nothing wrong with pointing out that a standard technique for disarming a bomb seems counterintuitive to a layperson. That’s the sort of observation that fuels curiosity and interesting discussion. I don’t think the OP was suggesting that it was the wrong technique.
dang 4y ago
"Please don't sneer, including at the rest of the community." It's reliably a marker of bad comments and worse threads. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

deleted 4y ago

[deleted]