6 ms·

I wonder why the US wouldn't lie about the effective depth range. Seems kinda dumb to telegraph to your enemies how far to dig.

by influx 1y ago

cjbgkagh 1y ago
The math isn’t that hard and the ideal case is a linear extrapolation so people can sit down with a calculator and figure it out.
- kcplate 1y ago
  You are still relying on parameters that they are disclosing to you.
  - deleted 1y ago
    [deleted]
  - cjbgkagh 1y ago
    There are physical limits to weight, hardness, max explosive energy and max kinetic energy and these are all known. The only way to exceed them would be to drop it from a higher altitude, like space, or give it a nuclear warhead. The US isn’t the only country that has tested bunker busters and the physics involved isn’t that hard. It’s just expensive.
    - kcplate 1y ago
      Sure, but you have no firsthand knowledge of that information. You are told the B2 can carry a certain payload weight. You are told the B2 has a certain operational ceiling. You are told the bombs are a certain weight. You are told the bombs are made from a certain material. You are told the bombs contain a certain type of explosive. Everything you know about this device and its capabilities came from an organization that has every motivation to publish specs that are just enough to raise the eyebrows of the people this device is supposed to scare hell out of, but they have less than zero motivation to publish specs that speak to maximum capabilities. So while your calculations might be accurate for the component values you gave it, your component values of your calculation are not accurate, because all you know is what you were told.
      - cjbgkagh 1y ago
        You can calculate these things based on wing size and airspeed and neither are hard to figure out, it’s clearly subsonic and it’s been seen in public. While skunkworks are certainly a thing they’re not hiding some Star Trek antigravity device, physics is still physics and physical limits are physical limits. Look at the Otto Celera 500L if you want to see what attacking physical limits looks like. It’s an engineering problem and the fundamentals are well understood. The real magic is in creating the money to pay for it.
        kcplate 1y ago
        > You can calculate these things based on wing size and airspeed If you can calculate the depth and damage those bombs did based on wing size and airspeed (which technically is another parameter you really don’t know, but are relying on what you are told) you ought to be working for the government.
        cjbgkagh 1y ago
        The US military isn't the only entity making airplanes and bunker busters. We don’t need to rely on their figures to know a great deal about what happened. You are assuming they have some order of magnitude hidden capacity which would break the laws of physics, and I’m very confident that they didn’t do that.
        kcplate 1y ago
        Gotcha. So your perspective is there are other entities making airplanes with the capabilities of the B-2 and a bunker buster bomb equivalent to the GBU-57 so much so that you can reliably determine capabilities of those weapon systems…as a layman with just a hand calculator? That is a $2B aircraft and a $20M ordinance (each). You want to tell us exactly what entity has anything even remotely equivalent? No one else but the US could bear to afford it. Maybe China…but if they have it’s not common knowledge. I think you have pretty much dug yourself a hole here on your knowledge and capabilities…you have landed into silliness now. (That pun was definitely intended)
- buildbot 1y ago
  The math is really that hard? I have no idea what the soil or rock is, what happens when the first bomb hits it, the second, and then the third? Does the timing matter? Does the timing matter if it's 5 minutes between? 1 hour between? Seconds between? Does the type of soil or rock compact or loosen when bombed? What's the variation in explosive yield? Does the ground transfer force from a shockwave well or poorly? Does that change after the first one? I really doubt this is very linear.
  - cjbgkagh 1y ago
    For it to be super-linear an additional meter of concrete / earth / whatever must be easier to penetrate than the one before it which I would classify as a physical impossibility. This is why linear is the ideal case.
    - ethbr1 1y ago
      Not with regard to multiple bombs. > Does the type of soil or rock compact or loosen when bombed? Is the most relevant question. It seems reasonable that fractured rock may be easier for subsequent bombs to penetrate.
      - cjbgkagh 1y ago
        Even if I were to accept the dubious premise that there is enough fractured rock to make a difference and there is no hampering with rocks falling into the void and that it's possible to hit the exact same spot repeatedly without touching the sides, all that would do in big O notation would be increase the constant factor. It would not be super linear after the second bomb. If your are talking about bombs that hit side by side then clearly that is sub-linear as no matter how fractured the rock it’s not easier to push through than air.
        ethbr1 1y ago
        An explosion creates a pressure wave. A pressure wave fractures rock. Fractured rock may be easier to pierce than solid rock. Ergo, if first bunker buster penetrates to maximum depth -20m and then explodes, fracturing rock within a __ radius, then second bunker buster travels through that fractured rock, the second (and so on) may be able to penetrate deeper. I have no idea about the physics of penetrating fractured vs non-fractured rock, but it's a physically plausible mechanism. Furthermore, given the multi-minute timeline reported, there's enough time for the bombs to be deployed sequentially.
larrled 1y ago
Credibility helps with deterrence.
deleted 1y ago
[deleted]
kcplate 1y ago
The real weapons system specs are never disclosed. Even on retired systems the real capabilities are often still classified because they can provide clues to their replacements capabilities.
maxglute 1y ago
It's a pretty dumb ordnance, gravity delivered GBU57 is a physics bound problem. The dimensions etc are known, you can give it the most optmistic assumptions, i.e. complete steel for max penetration, release at altitude where it reach max terminal velocity without grid fins deployed, run that through ndrc/young pentration equations etc. There aren't any super secret parameters for subterfuge like electronic warfare. Eitherway there's public videos of GBU57 in action - grid fins deployed to hit a traffic cone - defense autists counted frames, did napkin math, it's more or less what's purported ~ mach 0.8-1.2 penetrator designed for ~60m concrete. IIRC the assume sphere cow math for heavier all steel, no grid fin (i.e. not accurate), max out at mach ~2, doubles energy, penetrates ~80m. On the other hand, Fordow's construction time is known... as far as I know, many years before fgcc / uhpc and other "advanced" concrete formulas PRC formulated against US penetrators. And Israel probably has entire blue print, so who knows. E: quick lookup and GBU57 seems to be revealed shortly after guestimate of when Fordow started construction, possible Fordow could update design in anticipation, but then again, B2s were known entity and Iran's engineers can probably guestimate out what the maximum size/weight penetrator US could deliver on B2s before knowing GBU57 existed.
- anabab 1y ago
  What if it has some sort of a booster to increase its kinetic energy just before the hit? Also the behavior might improve in an area already weakened by a ventilation shaft/previous hit (first bomb turns 40 meters into fine gravel + detonates weakening quite a large are, second and third bomb easily go deeper)
  - maxglute 1y ago
    I think 1) is unlikely, b2 bays can't fit much more, gbu57 is mostly metal and no booster for penetration 2) is what no one knows, but we (as in the public) also don't know layout/construction, i.e. actual depth, bunker design (can emb sloped concrete/steel layer to deflect penetrators laterally so follow up drop don't go straight down).

I wonder why the US wouldn't lie about the effective depth range. Seems kinda dumb to telegraph to your enemies how far to dig.

by influx 1y ago

I wonder why the US wouldn't lie about the effective depth range. Seems kinda dumb to telegraph to your enemies how far to dig.

cjbgkagh 1y ago

The math isn’t that hard and the ideal case is a linear extrapolation so people can sit down with a calculator and figure it out.

kcplate 1y ago
You are still relying on parameters that they are disclosing to you.
- deleted 1y ago
  [deleted]
- cjbgkagh 1y ago
  There are physical limits to weight, hardness, max explosive energy and max kinetic energy and these are all known. The only way to exceed them would be to drop it from a higher altitude, like space, or give it a nuclear warhead. The US isn’t the only country that has tested bunker busters and the physics involved isn’t that hard. It’s just expensive.
  - kcplate 1y ago
    Sure, but you have no firsthand knowledge of that information. You are told the B2 can carry a certain payload weight. You are told the B2 has a certain operational ceiling. You are told the bombs are a certain weight. You are told the bombs are made from a certain material. You are told the bombs contain a certain type of explosive. Everything you know about this device and its capabilities came from an organization that has every motivation to publish specs that are just enough to raise the eyebrows of the people this device is supposed to scare hell out of, but they have less than zero motivation to publish specs that speak to maximum capabilities. So while your calculations might be accurate for the component values you gave it, your component values of your calculation are not accurate, because all you know is what you were told.
    - cjbgkagh 1y ago
      You can calculate these things based on wing size and airspeed and neither are hard to figure out, it’s clearly subsonic and it’s been seen in public. While skunkworks are certainly a thing they’re not hiding some Star Trek antigravity device, physics is still physics and physical limits are physical limits. Look at the Otto Celera 500L if you want to see what attacking physical limits looks like. It’s an engineering problem and the fundamentals are well understood. The real magic is in creating the money to pay for it.
      - kcplate 1y ago
        > You can calculate these things based on wing size and airspeed If you can calculate the depth and damage those bombs did based on wing size and airspeed (which technically is another parameter you really don’t know, but are relying on what you are told) you ought to be working for the government.
        cjbgkagh 1y ago
        The US military isn't the only entity making airplanes and bunker busters. We don’t need to rely on their figures to know a great deal about what happened. You are assuming they have some order of magnitude hidden capacity which would break the laws of physics, and I’m very confident that they didn’t do that.
        kcplate 1y ago
        Gotcha. So your perspective is there are other entities making airplanes with the capabilities of the B-2 and a bunker buster bomb equivalent to the GBU-57 so much so that you can reliably determine capabilities of those weapon systems…as a layman with just a hand calculator? That is a $2B aircraft and a $20M ordinance (each). You want to tell us exactly what entity has anything even remotely equivalent? No one else but the US could bear to afford it. Maybe China…but if they have it’s not common knowledge. I think you have pretty much dug yourself a hole here on your knowledge and capabilities…you have landed into silliness now. (That pun was definitely intended)
buildbot 1y ago
The math is really that hard? I have no idea what the soil or rock is, what happens when the first bomb hits it, the second, and then the third? Does the timing matter? Does the timing matter if it's 5 minutes between? 1 hour between? Seconds between? Does the type of soil or rock compact or loosen when bombed? What's the variation in explosive yield? Does the ground transfer force from a shockwave well or poorly? Does that change after the first one? I really doubt this is very linear.
- cjbgkagh 1y ago
  For it to be super-linear an additional meter of concrete / earth / whatever must be easier to penetrate than the one before it which I would classify as a physical impossibility. This is why linear is the ideal case.
  - ethbr1 1y ago
    Not with regard to multiple bombs. > Does the type of soil or rock compact or loosen when bombed? Is the most relevant question. It seems reasonable that fractured rock may be easier for subsequent bombs to penetrate.
    - cjbgkagh 1y ago
      Even if I were to accept the dubious premise that there is enough fractured rock to make a difference and there is no hampering with rocks falling into the void and that it's possible to hit the exact same spot repeatedly without touching the sides, all that would do in big O notation would be increase the constant factor. It would not be super linear after the second bomb. If your are talking about bombs that hit side by side then clearly that is sub-linear as no matter how fractured the rock it’s not easier to push through than air.
      - ethbr1 1y ago
        An explosion creates a pressure wave. A pressure wave fractures rock. Fractured rock may be easier to pierce than solid rock. Ergo, if first bunker buster penetrates to maximum depth -20m and then explodes, fracturing rock within a __ radius, then second bunker buster travels through that fractured rock, the second (and so on) may be able to penetrate deeper. I have no idea about the physics of penetrating fractured vs non-fractured rock, but it's a physically plausible mechanism. Furthermore, given the multi-minute timeline reported, there's enough time for the bombs to be deployed sequentially.

larrled 1y ago

Credibility helps with deterrence.

deleted 1y ago

[deleted]

kcplate 1y ago

The real weapons system specs are never disclosed. Even on retired systems the real capabilities are often still classified because they can provide clues to their replacements capabilities.

maxglute 1y ago

It's a pretty dumb ordnance, gravity delivered GBU57 is a physics bound problem. The dimensions etc are known, you can give it the most optmistic assumptions, i.e. complete steel for max penetration, release at altitude where it reach max terminal velocity without grid fins deployed, run that through ndrc/young pentration equations etc. There aren't any super secret parameters for subterfuge like electronic warfare. Eitherway there's public videos of GBU57 in action - grid fins deployed to hit a traffic cone - defense autists counted frames, did napkin math, it's more or less what's purported ~ mach 0.8-1.2 penetrator designed for ~60m concrete. IIRC the assume sphere cow math for heavier all steel, no grid fin (i.e. not accurate), max out at mach ~2, doubles energy, penetrates ~80m. On the other hand, Fordow's construction time is known... as far as I know, many years before fgcc / uhpc and other "advanced" concrete formulas PRC formulated against US penetrators. And Israel probably has entire blue print, so who knows. E: quick lookup and GBU57 seems to be revealed shortly after guestimate of when Fordow started construction, possible Fordow could update design in anticipation, but then again, B2s were known entity and Iran's engineers can probably guestimate out what the maximum size/weight penetrator US could deliver on B2s before knowing GBU57 existed.

anabab 1y ago
What if it has some sort of a booster to increase its kinetic energy just before the hit? Also the behavior might improve in an area already weakened by a ventilation shaft/previous hit (first bomb turns 40 meters into fine gravel + detonates weakening quite a large are, second and third bomb easily go deeper)
- maxglute 1y ago
  I think 1) is unlikely, b2 bays can't fit much more, gbu57 is mostly metal and no booster for penetration 2) is what no one knows, but we (as in the public) also don't know layout/construction, i.e. actual depth, bunker design (can emb sloped concrete/steel layer to deflect penetrators laterally so follow up drop don't go straight down).