Relative Damage Calculation for Nuclear and Explosive Weapons based on Tonnage

[Jujitsuguy]

Interesting rules question on damage calculation.

 

Referencing the 6E Equipment Guide, Pp. 219-221: Nuclear Weapons and "Effects of Nuclear Weapons".  The reference is using a 1MT Nuclear bomb on all the effects of the bomb for different damage and what-not.

 

That said, if I had a 100KT Nuclear Bomb--tactical Nuke, for example--how would the damage be calculated?

 

As per the book, the first effect is a 16-20d6 Drain against BODY, among other advantages. The base is 200AP.

 

If this were a conventional attack, I was at the understanding that every Halving of the energy is a reduction of 1DC. Is this incorrect?

How would we properly calculate the damage effects from a weapon that is 1/10 the size? Is there a documented reference I am missing here?

I may be oversimplifying this, but not sure how to find this.

 

Any wisdom on this is greatly appreciated.

[Cloppy Clip]

I can see two ways to go about this, depending on your tolerance for maths and assuming we're going with "Doubling energy adds +1 DC".

 

The first is to just take the progression used for STR and work out the minimum stage needed to get the required energy:

 

1 Mt = +0 DC

2 Mt = +1 DC

4 Mt = +2 DC

8 Mt = +3 DC

16 Mt = +4 DC

32 Mt = +5 DC

64 Mt = +6 DC

125 Mt = +7 DC

250 Mt = +8 DC

500 Mt = +9 DC

1 Gt = +10 DC

 

If working at a different level than megatons you can subtract or add lots of 10 DC to get to the right level. So to work out 100 kt, we'd first subtract 10 DC to get to 1 kt. Then we'd look up the smallest stage that's at least 100, which is 125 or +7 DC. So going from a base of 1 Mt = 200 AP, or 40 DC, 100 kt would be 40 - 10 + 7 = 37 DC. The advantage of this method is you don't have to do any calculations beyond shifting up or down in lots of 10. Otherwise it's just looking up a table.

 

If you don't mind doing some calculations, however, the expression to get the difference would be log2(X/1,000,000), where X is the TNT equivalent of your weapon. So, going back to 100 kt, we'd have log2(100,000/1,000,000) = -3.32..., which we can round to -3 and stick on to our base of 40 DC to get 37 DC, same as the previous answer.

 

For nearly all cases, these methods will give you the same answer give or take 1 DC, so just use whichever one you find more natural. Hope I've understood the question correctly and this helps, and apologies if not.

[unclevlad]

It...really doesn't work that well to do that.  It's 20d6 BODY Drain...with + 2 1/2 delayed return rate, NND (high radiation), +1 Does Body, MegaScale AoE + 1 1/2...and a few other things.  It's not 200;  it's 1050.  PLUS, there's also a 10d6 Drain CON with it;  it's a combined power.  It's 525.  So this part *alone* is 1575 active.  The doubling rules simply don't handle the notions.

 

In most cases, I think you'd drop down the intensity...but not that much.  The mechanics of the explosion drive the intensity.  The bigger aspect is a smaller radius;  the amount of material drives that.  There are several nuclear explosion calculators/simulators out there;  ICAN, the international campaign to abolish nuclear weapons, points to this one:

 

https://nuclearsecrecy.com/nukemap/

 

where you can play with yields, air or ground burst, etc.  Then compare the different radii to get a sense of how to translate it.  Note that it's quite possible that the points won't drop that much, because MegaScale is a very coarse advantage.

 

EDIT:  I'd suggest bringing up 2-3 copies of NukeMap, and set the same base conditions other than yield.  That would let you quickly compare things.  Particularly...go "small" with the 'terrorist nuke' which is only 10 kt.  The area in the fireball, the first effect:

 

Quote

Maximum size of the nuclear fireball; relevance to damage on the ground depends on the height of detonation. If it touches the ground, the amount of radioactive fallout is significantly increased. Anything inside the fireball is effectively vaporized.

 

Bold mine.  For a 10 kt device, ground burst?  It's still 200 meters.  "Tactical" nuke is a pretty gross euphemism.

[Duke Bushido]

Not trting to be funny here, but while I can see some curiosity here for those using rhe eukws to run a large scan tactical,skirmish game,oe a space battle, I would think that for a lot of us, 1050 AP is somewhere considerably north of the "plot device" line, isn't it?

 

 

[unclevlad]

That's ONE part of it.

 

The entire nuke is 5600+.

 

--Radiation...the BODY and CON drains mentioned already.  

--Flash:  defined as a 12d6 major transform (sighted to blind), with a massive, massive AoE during the day, and even bigger at night (duh)

--Thermal:  20d6 RKA mega explosion

--EMP:  Dispel electrical devices (all electrical devices, all functionality), 20d6, mega explosion

--blast (the overpressure wave):  another 20d6 RKA mega explosion, with a +1 Indirect to have it attack every part of a building...oh, and this lasts for 6 segments.

--reverse pressure.  The overpressure wave creates a vacuum.  This one's only 3d6 RKA mega explosion

--fires...a nasty combination of a minor, but huge, combustion effect...and a big, constant Aid Fire Powers...a full firestorm

 

Last are issues of residual radiation and fallout, and in a large-scale exchange, nuclear winter.  But those are couched in general terms because they depend on too many other factors.  I believe there's a site like I posted, where you can put in similar parameters, but also include ground or air, and wind direction, and it'll give an estimated fallout map, including coarse estimates of fatalities from the fallout.  

 

The overall bomb is over 5600 active.  OP's 100 kt?  Really not much less.  Even the terrorist's IED nuke, which is 10 kt, *likely* exceeds 3000.

 

Yes, it's more than a little past "plot device" unless, of course, one's doing Jack Bauer season 2.

 

[DentArthurDent]

Other than the STR Table, what rules or descriptions say that +1 DC is a doubling of energy?

I’ve been looking for an hour and haven’t found anything.

Any help would be appreciated.

[Duke Bushido]

No rules DAD; a very old gentlemen's agreement from 1st to 4th edition that this was how primary Characterisitcs worked: dive more DEX mesnt you were "twice as agile" while 5 more INT meant you were twice as quick-witted.

 

For what it is worth, considering the way the bell curve applied to Characteristic checks and Characteristics-based skills, I could never really buy into it, but it is a long-established thing that in general, diehard HERO fans do not like abstracts in general, so I suppose this idea was maybe comforting to some people?

 

SPD and defenses were clear indicators that figured stats didn't work that way, and honestly, it has been so long since anyone brought up the "5 equals x2" thing that I just assumed 5e laid out some kind of ruling on this.

 

 

[Hugh Neilson]

14 hours ago, unclevlad said:

That's ONE part of it.

 

The entire nuke is 5600+.

 

--Radiation...the BODY and CON drains mentioned already.  

--Flash:  defined as a 12d6 major transform (sighted to blind), with a massive, massive AoE during the day, and even bigger at night (duh)

--Thermal:  20d6 RKA mega explosion

--EMP:  Dispel electrical devices (all electrical devices, all functionality), 20d6, mega explosion

--blast (the overpressure wave):  another 20d6 RKA mega explosion, with a +1 Indirect to have it attack every part of a building...oh, and this lasts for 6 segments.

--reverse pressure.  The overpressure wave creates a vacuum.  This one's only 3d6 RKA mega explosion

--fires...a nasty combination of a minor, but huge, combustion effect...and a big, constant Aid Fire Powers...a full firestorm

 

Last are issues of residual radiation and fallout, and in a large-scale exchange, nuclear winter.  But those are couched in general terms because they depend on too many other factors.  I believe there's a site like I posted, where you can put in similar parameters, but also include ground or air, and wind direction, and it'll give an estimated fallout map, including coarse estimates of fatalities from the fallout.  

 

The overall bomb is over 5600 active.  OP's 100 kt?  Really not much less.  Even the terrorist's IED nuke, which is 10 kt, *likely* exceeds 3000.

 

Yes, it's more than a little past "plot device" unless, of course, one's doing Jack Bauer season 2.

 

Let's assume we get it wrong and we hold that IED nuke to a paltry 2000 Active - how much impact will it actually have in-game?  "A large area is obliterated and everyone within the area killed."  Does that need an AP count?  Will a PC at Ground Zero survive if the dice roll in his favour?

 

12 hours ago, DentArthurDent said:

Other than the STR Table, what rules or descriptions say that +1 DC is a doubling of energy?

I’ve been looking for an hour and haven’t found anything.

Any help would be appreciated.

 

While it has been stated in some editions (not sure how recently), it seems reasonable to assume that, if +5 STR is doubling and adds +1d6 damage (or +1 DC to a killing attack), then +1 DC equates to a doubling of energy (at least for normal and killing damage).  Then we get to interrelationships - +1 DC adds +1 BOD, so does that mean +1 BOD is twice as durable?  It requires +1 DC to kill.  Mixing arithmetic and geometric scales makes for some disconnects.

[unclevlad]

13 hours ago, DentArthurDent said:

Other than the STR Table, what rules or descriptions say that +1 DC is a doubling of energy?

I’ve been looking for an hour and haven’t found anything.

Any help would be appreciated.

 

I wouldn't want to say that.  To start with, open-ended exponential growth is a Very Bad Thing.  There's a really old exemplar.  A man does a service to the emperor of China.  The emperor tells the man to choose his reward.  The man says, "1 grain of rice today.  2 tomorrow.  4 the next day."  And so on.  It's on a chess board.

 

By day 15, it's at a pound (there's about 29,000 grains to a pound).  By day 25, it's a ton.  By day 35, it's a kiloton.  45, a million tons.

 

That's exponential growth.  

 

The only explicit exponential growth is in the STR chart, and realize why that was done:  because the basis was comic book supers.  In weight lifting, the clean and jerk world record is basically 270 kg.  That's also maximum effort...it's pushing STR.  OK, then.  How do we go from that, to 27,000 kg...27 tons?  That's up there for the comics but by no means rare.  And doing so without the cost becoming impossible?  And doing so without the damage becoming unmanageably large?

 

Hero uses exponential growth for lifting, AND linear growth for damage, to accommodate both.  If you're familiar with GURPS?  They use quadratic growth for lifting...the amount you can lift is related to your strength squared.  So to go from 270 kg to 27 mt is a factor of 100, so the STR *score* has to be multiplied by 10.  So the 16 STR to manage 270 kg...goes to 160 STR to manage 27 mt.  Oh.  Lifting strength in the comics requires extreme growth...ergo, exponential.  Or we'd *never* be able to make a real strongman type at a sane number of points.  

 

Insofar as damage, for the most part, damage and defenses are abstract.  There are some coarse, basic associations...hand guns, for example.  But you're still abstracting foot-pounds of force at impact to DCs of damage.  The former can be expressed as a continuous function of muzzle velocity and bullet weight;  the latter is a step function with few steps available.  There's a lot lost in translation.  

 

Some other things.  Damage isn't a function of energy in any case.  A 200 watt incandescent is using a lot of energy...but doing no damage.  Pop 200 watts into a pulse laser, and you can drill a hole through a steel plate.  It's about the intensity.  If you thrust with your fist...not a lot of damage.  If you have a knife in hand...a lot of damage.  There isn't any more force/energy to speak of;  it's that the energy is focused down onto a much smaller area, and is thereby more intense...and damaging.  

 

Basically, damage and defenses are NOT trying to model the real world with any kind of fidelity, so no, IMO, there's no basis to really say that +1 DC increases the energy by X in any consistent manner.

 

  

[unclevlad]

BTW, for me, to connect the scaling on lifting STR and damage...my principle is that every 5 points of STR over 20 justifies buying a separate DC for HTH damage.  Whether you buy it as a martial arts DC or as an HA.  Just having a 35 STR means you can buy 3 martial arts DCs.  You don't need any notion of chi;  it's just there.  

 

The reason is, this way if i want a 12d6 punch, I don't have to buy a 60 STR.  That's 100 tons.  There aren't that many supers *that* strong.  40 STR, 4d6 HA.  Or with martial arts, I can justify some of the DCs just with STR alone.  I'm not all that fond of the 15 STR but 6 DCs style, and at least, I'd like to have build options.  Some concepts work with lots of MA DCs;  some don't.

[Cloppy Clip]

20 hours ago, DentArthurDent said:

Other than the STR Table, what rules or descriptions say that +1 DC is a doubling of energy?

I’ve been looking for an hour and haven’t found anything.

Any help would be appreciated.

 

On page 172 of 6E2, the rules for determining the BODY of an object also follow the doubling rule: +1 BODY (the average amount dealt by +1 DC) equals x2 mass. And if you do twice the work, you'll get twice the effect so that tallies. To clarify a point I've seen some people get stuck on, the energy spent isn't always the same as the actual work done. Energy is just the capacity to do physical work, and damage is only a specific kind of work. So a lightbulb will spend its energy putting out light and heat all around it, while a pulse laser focuses the spent energy as heat onto a small point. Both can use the same amount of energy, but the laser will be much more efficient at dealing damage. And a gun with a greater muzzle energy can actually do less work to the target's body because the bullet pierces it much more smoothly, thus spending less energy inside all those squishy organs.

 

The inconsistency comes when some other elements work on a linear basis: velocity damage and throwing distance (there are tables in the Advanced Player's Guide you can use to convert both to a geometric scale, but be warned that the realistic throwing table gets the formula wrong and increases throwing distance by too much). On their own, either way would work perfectly well, but you get some friction when trying to mix the two together, but I suspect that's due to the game being designed to be played on a tabletop with a grid and all, meaning those more realistic movement speeds and throwing ranges would quickly get out of hand.

 

[unclevlad]

The Object and Wall Body tables have never made sense to me.  125 mm is 12.5 cm, or 5 inches.  5 inches of steel.  If it's got 11 BODY, then why, if I stack 2 back to back, do I only get 2 more?  Compare the object table on 171 to the wall chart.  Stone, per cubic meter, object table...19 BODY.  Wall body table...11 BODY.  I suspect the object and wall tables are rooted more in the base and vehicle rules than anything else, and the goal here is simplicity and ease of play rather than accurate modeling.

 

The point about guns is *seriously* messy.   You're correct;  the muzzle energy is only 1 factor.  What matters is the energy effectively applied to the target.  The high velocity penetrator type rounds can readily sail right through;  energy applied to the target is simply based on the velocity loss.  Sometimes not all that much.  OTOH...same bullet mass, same powder load, same ballistics...but now it's a frangible round of some type, or a mushrooming/expansion round, where the bullet body deforms and expands upon impact, do a LOT more damage for the same energy.  The expanding round makes a really BIG hole;  the frangible round becomes a mini-AoE attack.  BUT, a frangible may well do next to nothing against reasonable armor;  the individual pieces will fail to penetrate.

[Hugh Neilson]

11 hours ago, unclevlad said:

The Object and Wall Body tables have never made sense to me.  125 mm is 12.5 cm, or 5 inches.  5 inches of steel.  If it's got 11 BODY, then why, if I stack 2 back to back, do I only get 2 more?  Compare the object table on 171 to the wall chart.  Stone, per cubic meter, object table...19 BODY.  Wall body table...11 BODY.  I suspect the object and wall tables are rooted more in the base and vehicle rules than anything else, and the goal here is simplicity and ease of play rather than accurate modeling.

 

This is where the combination of arithmetic and geometric becomes obvious.

 

Make that single wall twice as thick and add 2 BOD (2?  Should be 1 if 2x mass = +1 BOD).

 

But put one wall 3 meters behind the other, and we get the wall's defenses twice, and 11 BOD each, before someone can get through both.

 

At some point, we have to accept abstractions for the game and move on.

[unclevlad]

Then how about a sensible abstraction instead of a terrible one?

[Cloppy Clip]

There's probably going to be some big consequence I haven't thought of, since I'm just spitballing, but could you use the same rules as the ones for combining STR to determine the total BODY of multiple objects? Work out the effective masses of each wall or barrier or what have you, total them up with the effective mass of the target based on the Object BODY rules, and convert back to a final result.

 

That said, thinking through this as I type it out, it causes a bit of a problem for Barriers. I suppose we just have to accept that the system will have these edge cases it doesn't handle well, when everything's so interconnected and it uses two different scales.

 

And that bit about different types of walls gaining different rates of BODY per thickness took me by surprise too when I looked it up. 😅

[Lord Liaden]

When Hero Games published its vehicle and equipment supplement for the 5E Star Hero line, Spacers Toolkit, it took the approach for statting nuclear weapons of just making them a very big Killing Attack with Mega-Area, rather than attempting to model a Power for each individual effect. In a combat scenario any individual without ridiculously high Defenses is instantly dead anyway. For game purposes any of those long-term effects, e.g. radiation poisoning, can be treated as plot devices subject to GM's discretion.

 

During the 5E era our forum colleague, Bartman, posted a table on which he had calculated the energy for a wide range of explosive effects in relative weights of TNT, and also using other units of energy, from small explosives to nuclear weapons, to planet destroyers, to the Big Bang, using the principle of doubling energy per Damage Class. He also provided real-world examples of equivalent explosions, and broke down his methodology. I'll Attach that table below.

DC Conversion (Bartman).doc