War between Israel -v- Iran & Co (merged threads)

[Presley Cannady]

Based on the Glaser link, a 20 MT attack (in theory) would take out 100% of Iran's population - and much more, depending on the weather conditions at the time of the attack.

The relationship between firepower and casualties isn't linear because population densities aren't linearly distributed. 25 percent of the Iranian population is at risk from a 5 gigaton strike because 67 percent of them live in cities and almost a third live in one province alone.

Turning Israel into glass would take much less - one can infer they (IDF) would launch on a verified launch from Iran and not wait to see whether the incoming was nuclear or non-nuclear. MAD, indeed, but what alternative would their missile officers have.

Less than ten to wipe out the entire urban population--91 percent of the total population.

[jmm99]

in practice. No, I did not.

Attack by 40 475 KT warheads would logically be targeted on the two dozen or so urban centers, mostly in western Iran in a roughly N-S strip along the Zagros chain. A favorable westerly wind and other weather conditions would also impact the rest of the country. Actual casualties - I haven't the foggiest idea - nor does anyone else, because we do not have a good test case.[*]

BTW: How many gigatons of nuclear capability do you think the US has ? And how many 1 MT warheads does 5 gigatons equal ?

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[*] In theory, a 1 MT warhead, airburst at 2000m, has roughly a 7km destructive radius (~ 150+ sq km) - and its Equivalent MegaTonnage (EMT) = 1 EMT. A larger warhead has a relatively smaller EMT - e.g., a 9 MT warhead has an EMT between 4 and 5. A smaller warhead has a relatively larger EMT - e.g, a 475 KT warhead would have an EMT greater than 0.5 and less than 1.0. These are population destroying concepts. For hardened targets, accuracy is the important factor + ground penetration cabability (if available).

[Presley Cannady]

in practice. No, I did not.

Attack by 40 475 KT warheads would logically be targeted on the two dozen or so urban centers, mostly in western Iran in a roughly N-S strip along the Zagros chain. A favorable westerly wind and other weather conditions would also impact the rest of the country. Actual casualties - I haven't the foggiest idea - nor does anyone else, because we do not have a good test case.[*]

That's the beauty, or ugliness, of nuclear weapons. We don't really need a fairly good test case. Given the scale of energy, physical size of the target area, and the mass of bodies associated with nuclear strike problems, error is almost always negligible. Put another way, a missile strike anywhere in the world takes on the order of minutes from order to completion. A 1 kT device will annihilate anything within a quarter of a klick of detonation at optimum burst height and torch anything flammable within a third of a mile. Put enough firepower on target and you can extend that zone of certainty arbitrarily; and there's no physical limit to the destruction you can put on target.

The entire exercise is disgustingly academic.

BTW: How many gigatons of nuclear capability do you think the US has ? And how many 1 MT warheads does 5 gigatons equal ?

FAS estimates 2330 MT (1430 MT deployed) as of 2007, with a peak 40-50 years ago at 20 gigatons. I remember reading that the total global stockpile exceeded 60 gigatons.

[*] In theory, a 1 MT warhead, airburst at 2000m, has roughly a 7km destructive radius (~ 150+ sq km) - and its Equivalent MegaTonnage (EMT) = 1 EMT.

A larger warhead has a relatively smaller EMT - e.g., a 9 MT warhead has an EMT between 4 and 5. A smaller warhead has a relatively larger EMT - e.g, a 475 KT warhead would have an EMT greater than 0.5 and less than 1.0. These are population destroying concepts. For hardened targets, accuracy is the important factor + ground penetration cabability (if available).

If I remember correctly, planners calibrated their slide-rules with somewhere north of 10 psi as the minimum overpressure of widespread destruction. Some power law will describe dissipation of overpressure as distance from point of detonation grows. Just remember, >10 psi will rip apart a human body and blow away reinforced concrete buildings. >1000 psi will fracture cast iron and >5000 psi will fracture steel.

[jmm99]

Yup, we're now on the same page as to current capabilities. Per FAS, US had 2007 deployed 1430 MT or 1.430 gigatons. Total EMT depends on sizes of warheads; FAS places 2007 deployed at 2060 EMT - US has mostly fractional 1 MT warheads - 3700 warheads deployed.

The power law for human and soft building destruction (which I'm sure someone can find) yielded a rule of thumb, where EMT ~ the 2/3 root of raw MT. So, 1 MT = 1 EMT (since all powers of 1 are 1). A fractional MT would have more bang for the buck - 475 KT (.475 MT) ~ 0.60 EMT. Big devices run the other way. 15 MT ~ 6 EMT; 50 MT ~ 14 EMT. So, there are some finite limits on the destructive power that can be put on a target. One could put 14 1 MTs on one target and ~ the effect of a 50 MT - except for "missile fratricide" (the first airburst will screw up the target environment for later arriving missiles).

A 60 gigaton total (60,000 MT) at height of Cold War is quite possible (FAS has ~ 20,000+ MT for US) because the USSR had some very large warheads (in MT, but lower in EMT).

As you say, all of this is an academic exercise, unless someone decides to turn the missile keys first.

[Surferbeetle]

If I remember correctly, planners calibrated their slide-rules with somewhere north of 10 psi as the minimum overpressure of widespread destruction. Some power law will describe dissipation of overpressure as distance from point of detonation grows. Just remember, >10 psi will rip apart a human body and blow away reinforced concrete buildings. >1000 psi will fracture cast iron and >5000 psi will fracture steel.

Overpressure (rocket or mortar) is no fun. Nukes are something beyond...

Gauge pressure or absolute pressure? 1 atm = 760 mm Hg = 14.7 psi, Dynamic pressure?

Lets think about steel metrics for a moment; what type, what condition, what thickness, what shape, what temp, how long has it been irradiated, and what was the dose?

A36 Structural Carbon Steel, anticipated tensile strength 400-550 ksi (k=kip=1,000 lbs)

A514 High-Yield strength Quenched & Tempered Alloy Steel, anticipated tensile strength 690-895 ksi

The Charpy V Notch Test (ASTM E23) is a reproducible way to characterize the amount of energy needed to fracture a material...the result is typically reported in ft-lbs.

Cast iron is more likely to shatter than steel, particularly in the instances discussed, but keep in mind that it is stronger than steel in certain instances and applications...

A study on pilots and overpressure

[Presley Cannady]

Overpressure (rocket or mortar) is no fun. Nukes are something beyond...

Amen to that.

Gauge pressure or absolute pressure? 1 atm = 760 mm Hg = 14.7 psi, Dynamic pressure?

Gauge.

Lets think about steel metrics for a moment; what type, what condition, what thickness, what shape, what temp, how long has it been irradiated, and what was the dose?

Plastic deformations will start much earlier than at the ultimate tensile strength. For most of these structural steels, we're talking about some double digit percentage on either side of 50,000 psi. Afterwards, we start talking about the dimensionless strain on the material.

Good points all, but notice that for the high yield strength steels we're talking about a good amount of carbon doping.

Which decreases their fracture points significantly. For load-bearing supports, they perform pretty well--this is why you have an intuitive notion of the skeleton of a well built building surviving a nuclear blast. But as cover, not so much.