B MIRV vs very high-yield bomb effectiveness

[hbombman]

TL;DR Summary

Is a MIRV system better than a very high-yield bombs?

Are MIRV strikes really more devastating the very high-yield explosions?
This is a simulation by nukemap that shows a MIRV strike of x10 1.2MT bombs detonating simultaneously and the other is a very high-yield explosion of 100MT. The thermal rays in the 100MT explosion cover the entire metropolitan area, while still giving large areas of destruction to the blast. MIRV may be more efficient blast wise but I believe some people would still be alive with the MIRV strike, while the 100MT explosion will incinerate the entire city.

What do you guys think?

 

[Klystron]

TL;DR Summary: Is a MIRV system better than a very high-yield bombs?

View attachment 359046
View attachment 359047
Are MIRV strikes really more devastating the very high-yield explosions?
This is a simulation by nukemap that shows a MIRV strike of x10 1.2MT bombs detonating simultaneously and the other is a very high-yield explosion of 100MT. The thermal rays in the 100MT explosion cover the entire metropolitan area, while still giving large areas of destruction to the blast. MIRV may be more efficient blast wise but I believe some people would still be alive with the MIRV strike, while the 100MT explosion will incinerate the entire city.

What do you guys think?

I no longer work or teach weapons systems but can help clarify two aspects of the OP.

A high-yield nuclear warhead explosion as diagrammed expands spherically from its entry point detonation, limiting its 'circle of destruction'.

A MIRV (multiple independently [targetable] reentry vehicle) disperses warheads over a much wider area, potentially inflicting more destruction to multiple targets than a single high-yield warhead.

Not considered in the OP, actual destruction by nuclear weapon explosion may not be optimal. Specialized nuclear weapons, MIRVed or not, are designed to deliver highly disruptive electromagnetic pulses (EMP) while potentially minimizing physical destruction.

 

[Bandersnatch]

Is this an equivalent comparison? As in, why compare a single 100 Mt warhead with ten 1.2 Mt warheads? Why not e.g. ten 10 Mt? Or ten 120 kt vs one 1.2 Mt? At least then there'd be an equivalence of yield.
But the criterion for comparison should probably be what can be carried by the same delivery vehicle, and I don't think the OP satisfies that at all.

 

[hbombman]

Is this an equivalent comparison? As in, why compare a single 100 Mt warhead with ten 1.2 Mt warheads? Why not e.g. ten 10 Mt? Or ten 120 kt vs one 1.2 Mt? At least then there'd be an equivalence of yield.
But the criterion for comparison should probably be what can be carried by the same delivery vehicle, and I don't think the OP satisfies that at all.

This is a fair point, however, one can imagine a bomber with either x10 1.2MT bombs or x1 100MT bomb. I just never understood why people underestimate these super high yield nukes. Yes a lot of energy is wasted. But wouldn't x10 1.2MT bombs use more U235/Pu239 than a single 100MT bomb? The primary I mean, is the only thing that is expensive in nukes, the secondary or third stage is not expensive. So in terms of efficiency, if one only had a certain amount of U235/Pu239, wouldn't it be better off to develop the higher yield weapon?

We know x10 10MT bombs would be way worse than a 100MT strike that's not fair. Modern nuclear weapon planners don't use 10MT bombs, they use 500kt-1.5MT bombs. So that's why I'm giving the 1.2MT (B83) play here.

No one wants to talk about the intense thermal rays, and in reality it would be way worse than the nukemap simulation. A 100MT blast would set people on fire perhaps beyond 75 miles from point of detonation. Even in this simulation, the entire metropolitan area of Tokyo and beyond is completely incinerated by the 100MT strike.

 

[Flyboy]

First off, do you have any idea how absurdly, impractically massive a 100MT bomb would be? It would be too heavy for use on a missile of any sort, requiring a direct attack by a bomber that would then be unable to survive the ensuing detonation. The crew testing the 50MT Tsar Bomba barely survived the test shot, and that was with basically every possible concession to their survival having been implemented.

Second, the point of a nuke is not mass casualties and flattening a city. That is a side effect of their use, not a primary objective. They are intended for use against either hardened targets such as strategic command and control bunkers, like NORAD HQ at Cheyenne Mountain in Colorado or SAC HQ at Offut AFB in Nebraska, missile silos, or diffuse, wide area soft (but still strategic) targets such as air force/army bases, shipyards/ports, logistics hubs, and major manufacturing centers. Most of the soft targets happen to be co-located with large population centers, ensuring the high collateral damage most people think of when contemplating Mutually Assured Destruction.

The point of MIRVs is less about increasing total destruction and more about hitting as many strategic targets with as few ICBMs as practical, while using improved accuracy to actually limit the collateral damage. If you can take out a wing of 18 Titan II ICBMs with only 3 missiles dropping 6 MIRVs, each one yielding 500kT, versus 18 missiles dropping a single 5MT each, which would you choose?

 

[hbombman]

First off, do you have any idea how absurdly, impractically massive a 100MT bomb would be? It would be too heavy for use on a missile of any sort, requiring a direct attack by a bomber that would then be unable to survive the ensuing detonation. The crew testing the 50MT Tsar Bomba barely survived the test shot, and that was with basically every possible concession to their survival having been implemented.

Second, the point of a nuke is not mass casualties and flattening a city. That is a side effect of their use, not a primary objective. They are intended for use against either hardened targets such as strategic command and control bunkers, like NORAD HQ at Cheyenne Mountain in Colorado or SAC HQ at Offut AFB in Nebraska, missile silos, or diffuse, wide area soft (but still strategic) targets such as air force/army bases, shipyards/ports, logistics hubs, and major manufacturing centers. Most of the soft targets happen to be co-located with large population centers, ensuring the high collateral damage most people think of when contemplating Mutually Assured Destruction.

The point of MIRVs is less about increasing total destruction and more about hitting as many strategic targets with as few ICBMs as practical, while using improved accuracy to actually limit the collateral damage. If you can take out a wing of 18 Titan II ICBMs with only 3 missiles dropping 6 MIRVs, each one yielding 500kT, versus 18 missiles dropping a single 5MT each, which would you choose?

If my goal was destroy enemy missile instillations then I'd take the MIRV. But that's not the discussion here.

Also you said "First off, do you have any idea how absurdly, impractically massive a 100MT bomb would be? It would be too heavy for use on a missile of any sort, requiring a direct attack by a bomber that would then be unable to survive the ensuing detonation. The crew testing the 50MT Tsar Bomba barely survived the test shot, and that was with basically every possible concession to their survival having been implemented."

First off we have unmanned drones now. Why can't one make an airplane that is a huge nuke? Just unmanned?

Again you people are trying to stay away from the physical destruction and trying instead to go towards the practicality of MIRVs.

Lastly, I don't know why you think counter-value targets won't be struck. Cities are going to be targeted in any major nuclear offensive. If nothing more than you don't know if there could be secret nukes within said city.

Tokyo was destroyed in this instance in a more severe manner by the 100MT explosion then the ×12 1.2MT bombs.

I just don't think people should underestimate high yield bombs.

 

[Frabjous]

I just don't think people should underestimate high yield bombs.

Given that the maximum warhead size for the US and Russia has been decreasing over the years, yours is a minority viewpoint.

 

[Flyboy]

If my goal was destroy enemy missile instillations then I'd take the MIRV. But that's not the discussion here.

Then what is? Oh, right:

Is a MIRV system better than a very high-yield bombs?

That is a very open-ended and vague question that is open to interpretation.

The only time one massive bomb is superior to a MIRV-type attack is political posturing. That’s the only reason they built Tsar Bomba: because Khrushchev wanted to have the biggest dick in the nuclear arms race, and by god he succeeded. It was not a military weapon, it was a weapon of intimidation, of posturing and politics. And it worked… kinda. It helped force both the US and USSR back to the negotiating table to hammer out the Partial Test Ban Treaty.

First off we have unmanned drones now. Why can't one make an airplane that is a huge nuke? Just unmanned?

Two words: Air. Defense.

Drones are not magically able to slip through a modern air defense network, not when they’re big enough to carry this hunchfuster:

That is what it takes to make a 100MT bomb. That’s a replica of Tsar Bomba, which was theoretically capable of such a yield with some minor tweaks to materials choices.

And you think you can just waltz through hostile airspace fat, dumb, and happy while carrying that? Good luck with anything short of a stealth bomber.

Again you people are trying to stay away from the physical destruction and trying instead to go towards the practicality of MIRVs.

Uhhhh, yes? Because nuclear weapons are inherently a political weapon, not a military one. And an incredibly expensive and security-senstive one at that. You want the most possible bang for your buck, ruble, etc., and the best way to accomplish that is MIRVs.

Lastly, I don't know why you think counter-value targets won't be struck. Cities are going to be targeted in any major nuclear offensive. If nothing more than you don't know if there could be secret nukes within said city.

Because cities are gonna get hit anyways just from hitting the military targets.

Case in point: I grew up in the suburbs of Sacramento, California. There were three valid military targets for Soviet nukes within the metro: McClellan AFB, a major repair depot for fighters and fighter bombers; Mather AFB, a Strategic Air Command B-52 base on nuclear alert; and the Sacramento Army Depot. Probable additional targets on the quasi-military standpoint were Aerojet’s main facility, not far from Mather, and the Union Pacific rail yard in Roseville.

Just those three military bases would have created overlapping fields of destruction that would have laid waste to significant chunks of the Sacramento metro area, and would have severely damaged the state capital area near downtown, as well as the nearby I-80/I-5 freeway interchange, which would be a critical logistical node for any war effort. Were there probably a few more warheads allocated to the area? Most likely, but only because Sacramento is a state capital and a major logistics hub for the West Coast.

Also, “secret nukes”???!? Seriously? Sir, you don’t keep secret weapons of that power in a busy population center. It’s begging for trouble. You stick your ace in the hole in a SSBN and park it in the deep ocean where it’s damn near impossible to locate.

Tokyo was destroyed in this instance in a more severe manner by the 100MT explosion then the ×12 1.2MT bombs.

Well, sure, because you are comparing apples and oranges… or perhaps more accurately, you’re comparing a 5.56mm NATO rifle round to a .50 BMG round. It’s a completely different class. Your one big bomb has nearly an order of magnitude more energy than your MIRV scenario.

Put a Castle Bravo (15MT) out instead of the uprated/full power Tsar Bomba and try your comparison again. I think you will find that the MIRV wins. Handily.

I just don't think people should underestimate high yield bombs.

Look, I love a big boom as much as the next guy, but I think you’re too fixated on the raw destructive power instead of the bigger picture of why you use a nuke.

 

[Bandersnatch]

This is a fair point, however, one can imagine a bomber with either x10 1.2MT bombs or x1 100MT bomb.

Why 10? Why not 24? At least that would match the capacity of a modern production plane. You see what I'm getting at, right? You're comparing how efficiently one can transport some load (destruction potential) with a delivery vehicle, only you have one test truck loaded with such an oversized cargo that it needed an extra set of wheels fitted, while the other truck is not even half full.
Also, other than the title, there's no MIRV here.
You want to make the comparison fair if you want to make a point.

Also also, what do you have against the Japanese, man? Burning Tokyo to the ground is so WWII. Shouldn't you be nuking Nuuk?

 

[hbombman]

Two words: Air. Defense.

Drones are not magically able to slip through a modern air defense network,

Ok bro, this is 2025, they do have stealth drones, not to mention aircraft you don't know about such as the new F-47. There are countermeasures to anti-aircraft weapons.
But again you are straying away from the main point: forget anti-air, forget the weight and impracticality of a tsar bomb, forget even a realistic war scenario. This is a physics question not a military one. At the end of the day a 100MT bomb is nothing to sneeze at and I'm tired of people saying that a MIRV is always better than high yield warheads. It's a massive explosion that would annihilate vast regions of land. Don't let it be a ground burst or Japan might be blanketed in fallout, especially if it was a three-stage bomb.

Why 10? Why not 24? At least that would match the capacity of a modern production plane. You see what I'm getting at, right? You're comparing how efficiently one can transport some load (destruction potential) with a delivery vehicle, only you have one test truck loaded with such an oversized cargo that it needed an extra set of wheels fitted, while the other truck is not even half full.
Also, other than the title, there's no MIRV here.
You want to make the comparison fair if you want to make a point.

Because we both know x24 1.2MT warheads would be far worse than the 100MT strike - and it would require at least x2 missiles or probably at least x2 bombers. You guys keep talking about how a 100MT warhead can't fit in a missile or a bomber without it being slow ~ I have addresses this with stealth drones, albeit a large one, but stealth nevertheless. So that takes care of anti-air mostly.

Even if we added x5 more 1.2MT to the picture for a total of x15, the 100MT would still be worse because of the thermal radiation. The firestorm would probably extend past Tokyo well into the mountains and even threatening Kyoto.

Also, “secret nukes”???!? Seriously? Sir, you don’t keep secret weapons of that power in a busy population center. It’s begging for trouble. You stick your ace in the hole in a SSBN and park it in the deep ocean where it’s damn near impossible to locate.

Tell that to the USSR whom likely had an entire secret mountain hollowed out full of H Bombs.
Yes SLBMs in submarines are ideal but we also have mobile truck launched missiles, the Russians got a lot of em, and can mount and 800kt nuke on them. That's equivalent to a poor man's nuclear sub IMO. You can't really track it, because it's mobile.

And how is that asking for trouble if you need launch codes to even activate it?

The only time one massive bomb is superior to a MIRV-type attack is political posturing. That’s the only reason they built Tsar Bomba

This is false, large bombs have their uses when missile accuracy is an issue, or especially relevant nowadays ~ when you're trying to take out a fortified military installation like the one in Wyoming, which would take over 30MT to destroy in one hit. Or if you're trying to destroy natural barriers such as mountains, or radioactive fallout especially. If just one 100MT bomb hit NYC in a ground burst not only would NYC be vaporized but if the wind was blowing west than we're talking about multiple states populations being exposed to thousands of rads every hour. That's death. That's something a MIRV strike in one city couldn't do.

Given that the maximum warhead size for the US and Russia has been decreasing over the years, yours is a minority viewpoint.

We know why they went to MIRVs it was to countermeasure anti ballistic missile technology such as SDI. It's easier to shoot down a big warheads then x12 with x30 more decoys and dummy warheads. Also it's more efficient in terms of destroying enemy nuclear missiles bases because that requires precision strikes that expose the silos to high psi blast overpressure or a direct hit. The missiles can be spaced out over many miles so that's why.
But again you are straying away from the point: that a 100MT bomb in a single city could be way worse than a MIRV strike. Due to: thermal radiation, and radioactive fallout.

or perhaps more accurately, you’re comparing a 5.56mm NATO rifle round to a .50 BMG round.

I'd rather be shot with x4 5.56x45mm rounds than a single .50BMG. people have survived 5.56 rounds you'd be surprised...

 

[Frabjous]

Or if you're trying to destroy natural barriers such as mountains, or radioactive fallout especially. If just one 100MT bomb hit NYC in a ground burst not only would NYC be vaporized but if the wind was blowing west than we're talking about multiple states populations being exposed to thousands of rads every hour.

You are fundamentally misunderstanding military utility which drives targeting decisions. For example, I do not see any significant increase in military utility in killing every New Yorker instead of 1M of them.

 

[Flyboy]

Okay, @hbombman , since you want to make it about “just the physics”, let’s make it just about the physics.

Your comparison is completely flawed by “just the physics” because you are comparing two scenarios that are nearly an order of magnitude apart: 100 MT vs 12 MT total yield.

To have an equivalent yield of multiple smaller bombs requires 80 bombs. Not 10, 80.

That is why I made the comparison between the two different cartridges. Yes, people can and have survived multiple 5.56 round hits. But in this comparison, it’s the difference between being hit by 1, and being hit by a trigger-happy idiot running a 30 round mag dump because he thinks it’s funny, or because he wants to make sure you’re completely, unrecoverably dead.

Now, your concept of “one big bomb vs a bunch of little bombs”, using Nukemap, cannot be effectively modeled. I tried. It refused to give me hard casualties (which seems to be your criteria here) for multiple bombs. So, we’re just going to have to do a comparison on effects coverage instead.

And for the sake of discussion, we will be doing the following, more even comparison: Castle Bravo (15MT) vs 12x 1.2MT (14.4MT total yield).

Now, this was done quickly on my phone and certainly could be optimized, but it should give you an idea:

Castle Bravo:

12x 1.2MT:

Look at the difference in scale.

I would provide hard casualties if it was able to provide it, but it throws an error from so many.

And for comparison, your beloved full-yield Tsar Bomba:

Even more efficiently placed than my quick and dirty placement, I think you can see that 80 warheads would easily exceed the destructive zone of the biggest single bomb.

Now, as a comparison between your hard numbers on casualties…

Castle Bravo:

And the mythical 100MT monster bomb, detonated at the exact same spot:

For a 6.67x increase in yield, you are seeing a ~3.1x increase in fatalities, and a ~2.15x increase in injuries/casualties.

Bigger is not inherently better.

Drops mike

 

[KB0001]

You need 8 times the yield to double the blast radius. you all are forgeting we live in a 3D world. If 1 Mt destroys 5km. Then you all think 2Mt will destroy 10km.....WRONG. The blast has to double or travel in the X, Y, Z axis.

So, You have to double the yield 3 times. 2x2x2 =8. Originally we used multiple re-entry vehicles unguided on it terminal path for 1 target. So, the missiles would have 3 warheads released high enough to spread out by a few miles. The error of dispersion (mean point impact and probable error).

The accuracy of the first nukes missiles was bad, a few mile off target was not uncommon. (even Fat man used during WW2 was 8000 ft off target, when the error of probability was that 50% of all round would fall 1000ft off target) They were told to only drop Fat man if they had visual targeting and not to use radar, but I bet they use radar b/c it was very heavy cloud cover, and Nagasaki was not the primary target, as the first target was totally overcast. They just didn't want to fly home and land w/ a nuke on board....heheh anyway I could go on, but I'm tired so take it light --KB