5 ms·

> Jones found that of the four safety mechanisms in the Faro bomb, designed to prevent unintended detonation, three failed to operate properly 3/4 of the safet

by wnevets 13y ago

> Jones found that of the four safety mechanisms in the Faro bomb, designed to prevent unintended detonation, three failed to operate properly 3/4 of the safety mechanisms on a 4 megaton bomb failed over US soil. I would hardly call this a breathless article.

stevetursi 13y ago
> and it was only that final, highly vulnerable switch that averted calamity What does "highly vulnerable" even mean? Could it have been triggered by the wind? If I'm the guy at the control panel, am I accidentally hitting that switch a couple of times per week? Maybe the only way that switch gets triggered is if I black out from the stress and my nose hits it on my way to the floor. I get the significance of three/four barriers failing, but if the fourth one has a one-in-a-billion chance, is it really fair to say North Carolina was "dramatically close" to being nuked?
- wnevets 13y ago
  > the final switch that prevented disaster could easily have been shorted by an electrical jolt I would say its fair, would you feel safe if all bombs only had this switch from the 50s?
  - stevetursi 13y ago
    So he means something like what a surge protector blocks? I suppose they could have neglected to put a fuse in the circuit which should have protected it against a surge that would damage some very expensive equipment (not to mention cause nuclear detonation.) But I don't know. I wasn't there to see and I didn't read the report. And we all know fuses fail as well - would that be the fourth out of five failsafes? To answer your question, no - I honestly would not feel safe. But "dramatically close" is different altogether. When I think "dramatically close" I think about the time my kid ran into the street and I grabbed him from in front of a car... I needed to act urgently to avoid disaster. I could be wrong though (and often am.)
    - wnevets 13y ago
      According to the wiki it disintegrated on impact, I'm sure that played a role in the "dramatically close" statement
  - smsm42 13y ago
    That's like comparing losing a lottery by guessing only 3 numbers out of 4 and playing a lottery where you need to guess only one number. These are statistically very different events, since you don't guess other 3 numbers correctly every time - and all fail-safes aren't failing at the same time. That's the point of having many of them - if each of them fails one-in-a-million time, you get 10^24 of security.
    - nostromo 13y ago
      Here we have a sample of 8 safety measures across two bombs with 3 failures. That's not 1 in a million, that's 1 in 3.
      - corin_ 13y ago
        That's not how probability works, though. I could go and buy a lottery ticket tomorrow for the first time in my life and win the jackpot, it wouldn't mean that the odds of winning are 100%.
        nostromo 13y ago
        No, this isn't a problem of probability, it's a problem of "not enough data." Based on this tiny sample, here's the lottery analogy: The lottery will flip 4 coins that have a 37.5% chance of being heads. If you roll 4 heads lots of people die. So, just using this very inadequate sample from a single declassified document, you could estimate that a misfired bomb has a 2% chance of detonation (37.5%^4). Obviously none of us know the real dataset, but my point is simply that it's not comforting that so many safety measures failed. (Which, as it happens, is also the opinion of the author of the original report in the article.)
        corin_ 13y ago
        > No, this isn't a problem of probability, it's a problem of "not enough data." That was exactly my point, that with such little data you cannot judge the probability.
      - 13y ago
- coldtea 13y ago
  >What does "highly vulnerable" even mean? Could it have been triggered by the wind? Maybe the breeze of the wind is less potent than a impact of the drop of a heavy metallic object from an airplane.
- m4x 13y ago
  From http://en.m.wikipedia.org/wiki/1961_Goldsboro_B-52_crash http://en.m.wikipedia.org/wiki/1961_Goldsboro_B-52_crash : Later, however, it was found that both bombs were fully functional and that a single low-voltage switch was indeed all that stood between detonation. The switch they're referring to is the arm/safe switch on the pilot's control panel. So the bombs didn't fail, one of them armed and tried to detonate exactly as designed when dropped from an aircraft. The only reason it didn't was because the pilot's arming circuit hadn't been activated. This isn't very reassuring because that arming switch may well have simply been a toggle switch under a cover, and even if it was better protected it still almost certainly boiled down to simply closing one or a pair of contacts, which can quite conceivably happen accidentally while bailing out of a spinning aircraft. Not exactly a one-in-a-billion chance. There is a discrepancy between what TFA says (three out of four safety circuits) and what the wiki says (five out of six arming circuits) and I can't find anything to clear that up on my phone. Either way it's a disconcerting piece of history
  - einhverfr 13y ago
    I think once you are dealing with an out of control aircraft that disintegrates in the air, all bets are off.
    - nitrogen 13y ago
      A nuclear bomb has to detonate in the right way in order to produce a nuclear explosion. Otherwise, it should just break apart. From that I assume it should be possible to design a bomb and corresponding delivery system that are highly unlikely to detonate by accident, even if your plane blows up or rips apart in midair.
      - einhverfr 13y ago
        It should be possible to design a nuclear power plant to operate safely after a magnitude 9 earthquake and a tsunami following it, but I would still say in that case all bets are off. The problem is that there are certain sorts of disasters where you really can't be sure you have the unknowns down well enough..... That's why aircraft components are rigorously tested. The only really safe solution I can think of is to try to anticipate the problem and sabotage the warhead first. For example one might, say, design warheads to destroy portions of the electronics if they get a signal that the pilot ejected. So yes, it is probably possible. Is it possible to do so reasonably perfectly? I doubt it to be honest.
cpleppert 13y ago
If the safety mechanisms are failing catastrophically then how will the bomb even detonate? The timing mechanisms have to execute perfectly to get a full power detonation and should be designed to become inert in a catastrophic breakup anyway. If any part of the switching mechanism becomes damaged the bomb should should/could be designed not to be able to detonate without relying on any electrical switches.
- TylerE 13y ago
  Because even if "fizzles" and goes off at 1% yield, Goldsboro, NC (which is, incidentally, about 20 miles from where I live) is a crate. Even at 1% yield that is 3x the Hiroshima bomb.
  - jlgreco 13y ago
    A fizzle of the (relatively small, fission) primary would be some percentage of a number much lower than 4 megatons. Most of that "oomph" comes from the fusion secondary which is set off by the primary detonating as designed. I don't know how big the primary on that bomb was, and can't find anything about that, but did find this (http://en.wikipedia.org/wiki/Castle_Koon http://en.wikipedia.org/wiki/Castle_Koon) test of a fusion bomb where the primary didn't fizzle but the secondary nevertheless did not ignite. The primary there was 110 kilotons. So the primary on that bomb, not fizzling, is around 5 or 6 Nagasaki blasts.
    - ballard 13y ago
      How much energy is yielded by "fusion" secondaries ([1st]fission - [2nd]fusion-fission) varies by design, but secondary's fusion is used for more efficient (eg more complete) fission. Only huge bombs have tertiary fusion stages that contribute much more yield than fission stages. http://en.wikipedia.org/wiki/Teller-Ulam_design http://en.wikipedia.org/wiki/Teller-Ulam_design
      - jlgreco 13y ago
        I'm not sure what you mean, the W39 was a Teller-Ulam design bomb. It wasn't a boosted fission bomb (though maybe the primary was? I don't know). I believe the Castle bombs were as well.

by wnevets 13y ago

stevetursi 13y ago

> and it was only that final, highly vulnerable switch that averted calamity What does "highly vulnerable" even mean? Could it have been triggered by the wind? If I'm the guy at the control panel, am I accidentally hitting that switch a couple of times per week? Maybe the only way that switch gets triggered is if I black out from the stress and my nose hits it on my way to the floor. I get the significance of three/four barriers failing, but if the fourth one has a one-in-a-billion chance, is it really fair to say North Carolina was "dramatically close" to being nuked?

wnevets 13y ago
> the final switch that prevented disaster could easily have been shorted by an electrical jolt I would say its fair, would you feel safe if all bombs only had this switch from the 50s?
- stevetursi 13y ago
  So he means something like what a surge protector blocks? I suppose they could have neglected to put a fuse in the circuit which should have protected it against a surge that would damage some very expensive equipment (not to mention cause nuclear detonation.) But I don't know. I wasn't there to see and I didn't read the report. And we all know fuses fail as well - would that be the fourth out of five failsafes? To answer your question, no - I honestly would not feel safe. But "dramatically close" is different altogether. When I think "dramatically close" I think about the time my kid ran into the street and I grabbed him from in front of a car... I needed to act urgently to avoid disaster. I could be wrong though (and often am.)
  - wnevets 13y ago
    According to the wiki it disintegrated on impact, I'm sure that played a role in the "dramatically close" statement
- smsm42 13y ago
  That's like comparing losing a lottery by guessing only 3 numbers out of 4 and playing a lottery where you need to guess only one number. These are statistically very different events, since you don't guess other 3 numbers correctly every time - and all fail-safes aren't failing at the same time. That's the point of having many of them - if each of them fails one-in-a-million time, you get 10^24 of security.
  - nostromo 13y ago
    Here we have a sample of 8 safety measures across two bombs with 3 failures. That's not 1 in a million, that's 1 in 3.
    - corin_ 13y ago
      That's not how probability works, though. I could go and buy a lottery ticket tomorrow for the first time in my life and win the jackpot, it wouldn't mean that the odds of winning are 100%.
      - nostromo 13y ago
        No, this isn't a problem of probability, it's a problem of "not enough data." Based on this tiny sample, here's the lottery analogy: The lottery will flip 4 coins that have a 37.5% chance of being heads. If you roll 4 heads lots of people die. So, just using this very inadequate sample from a single declassified document, you could estimate that a misfired bomb has a 2% chance of detonation (37.5%^4). Obviously none of us know the real dataset, but my point is simply that it's not comforting that so many safety measures failed. (Which, as it happens, is also the opinion of the author of the original report in the article.)
        corin_ 13y ago
        > No, this isn't a problem of probability, it's a problem of "not enough data." That was exactly my point, that with such little data you cannot judge the probability.
    - 13y ago
coldtea 13y ago
>What does "highly vulnerable" even mean? Could it have been triggered by the wind? Maybe the breeze of the wind is less potent than a impact of the drop of a heavy metallic object from an airplane.
m4x 13y ago
From http://en.m.wikipedia.org/wiki/1961_Goldsboro_B-52_crash http://en.m.wikipedia.org/wiki/1961_Goldsboro_B-52_crash : Later, however, it was found that both bombs were fully functional and that a single low-voltage switch was indeed all that stood between detonation. The switch they're referring to is the arm/safe switch on the pilot's control panel. So the bombs didn't fail, one of them armed and tried to detonate exactly as designed when dropped from an aircraft. The only reason it didn't was because the pilot's arming circuit hadn't been activated. This isn't very reassuring because that arming switch may well have simply been a toggle switch under a cover, and even if it was better protected it still almost certainly boiled down to simply closing one or a pair of contacts, which can quite conceivably happen accidentally while bailing out of a spinning aircraft. Not exactly a one-in-a-billion chance. There is a discrepancy between what TFA says (three out of four safety circuits) and what the wiki says (five out of six arming circuits) and I can't find anything to clear that up on my phone. Either way it's a disconcerting piece of history
- einhverfr 13y ago
  I think once you are dealing with an out of control aircraft that disintegrates in the air, all bets are off.
  - nitrogen 13y ago
    A nuclear bomb has to detonate in the right way in order to produce a nuclear explosion. Otherwise, it should just break apart. From that I assume it should be possible to design a bomb and corresponding delivery system that are highly unlikely to detonate by accident, even if your plane blows up or rips apart in midair.
    - einhverfr 13y ago
      It should be possible to design a nuclear power plant to operate safely after a magnitude 9 earthquake and a tsunami following it, but I would still say in that case all bets are off. The problem is that there are certain sorts of disasters where you really can't be sure you have the unknowns down well enough..... That's why aircraft components are rigorously tested. The only really safe solution I can think of is to try to anticipate the problem and sabotage the warhead first. For example one might, say, design warheads to destroy portions of the electronics if they get a signal that the pilot ejected. So yes, it is probably possible. Is it possible to do so reasonably perfectly? I doubt it to be honest.

cpleppert 13y ago

If the safety mechanisms are failing catastrophically then how will the bomb even detonate? The timing mechanisms have to execute perfectly to get a full power detonation and should be designed to become inert in a catastrophic breakup anyway. If any part of the switching mechanism becomes damaged the bomb should should/could be designed not to be able to detonate without relying on any electrical switches.

TylerE 13y ago
Because even if "fizzles" and goes off at 1% yield, Goldsboro, NC (which is, incidentally, about 20 miles from where I live) is a crate. Even at 1% yield that is 3x the Hiroshima bomb.
- jlgreco 13y ago
  A fizzle of the (relatively small, fission) primary would be some percentage of a number much lower than 4 megatons. Most of that "oomph" comes from the fusion secondary which is set off by the primary detonating as designed. I don't know how big the primary on that bomb was, and can't find anything about that, but did find this (http://en.wikipedia.org/wiki/Castle_Koon http://en.wikipedia.org/wiki/Castle_Koon) test of a fusion bomb where the primary didn't fizzle but the secondary nevertheless did not ignite. The primary there was 110 kilotons. So the primary on that bomb, not fizzling, is around 5 or 6 Nagasaki blasts.
  - ballard 13y ago
    How much energy is yielded by "fusion" secondaries ([1st]fission - [2nd]fusion-fission) varies by design, but secondary's fusion is used for more efficient (eg more complete) fission. Only huge bombs have tertiary fusion stages that contribute much more yield than fission stages. http://en.wikipedia.org/wiki/Teller-Ulam_design http://en.wikipedia.org/wiki/Teller-Ulam_design
    - jlgreco 13y ago
      I'm not sure what you mean, the W39 was a Teller-Ulam design bomb. It wasn't a boosted fission bomb (though maybe the primary was? I don't know). I believe the Castle bombs were as well.