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Old 02-05-2022, 12:35 PM   #1
GURPS Fox
 
Join Date: Jun 2020
Default 3e Nuke Design Rules

So, I've been working on a CnC Tiberium/Generals fusion setting and one of the weapons that is (sadly) common is nuclear ordinance. Specifically, for things like torpedoes and artillery.

So far I've been using what little Vehicles 2e (for GURPS 3e) has and quite a bit of guesswork (using the special warhead size modifier) but I've been told that it is a bad way to design nukes.

One of the pieces of nuke-equipped ordinance is a torpedo based on the Mk48, a 530mm torpedo. Using my 'dirty' calculations, the torpedo would have a 148kT warhead. A damage output that would come out as 12dx296,000,000/6dx505,880 if you use the 'standard' calculations or the 'tame' calculations respectively.

Is there anything that I could use to make my nuke design easier?
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Old 02-05-2022, 02:43 PM   #2
johndallman
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Default Re: 3e Nuke Design Rules

Quote:
Originally Posted by GURPS Fox View Post
One of the pieces of nuke-equipped ordinance is a torpedo based on the Mk48, a 530mm torpedo. Using my 'dirty' calculations, the torpedo would have a 148kT warhead. A damage output that would come out as 12dx296,000,000/6dx505,880 if you use the 'standard' calculations or the 'tame' calculations respectively.
That warhead is way too powerful for submarine use. It will destroy the launching submarine via the shockwave, which is very powerful underwater. Historical nuclear torpedoes have had much less yield: the most powerful one deployed appears to have been the USN's Mark 45 torpedo, at 11kT, and using that was regarded as dangerous to the firer.
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Old 02-05-2022, 04:11 PM   #3
Fred Brackin
 
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Default Re: 3e Nuke Design Rules

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Originally Posted by GURPS Fox View Post
S
Is there anything that I could use to make my nuke design easier?
No. Realistic nuclear weapon design would be excedingly complicated and make Homeland Security nervous.

I believe the 4e version of HT has some data on the Hiroshima and Nagasaki devices though modern warheads are much smaller.

You can get a _possibly_ accurate overview from Wikipedia. This has some things that have been generally known for some time. Such as critical mass sizes based on physics and soem important design features that are not really intuitive.

For example, after you get your basic nuclear warhead you can double yield by adding a "boosted phase". In a mdern warhead this involves injecting deuteriumand tritum gas into the hollow core of the warhead durign the arming process.There they will undergo fusion when the warhead is detonated and essentially double the amount of neutrons. What does this cost in terms of mass and $? Essentally nothing in mass and very little in terms of $ compared to the plutonium core.

Note that this is not at all what any version of the Gurps rules tell you. Those rules are designed for play balance and intuitive sorts of logic where more results cost more mass and more money in proportion to the increase in yield. That's not how real world nukes work.
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Old 02-05-2022, 06:58 PM   #4
GURPS Fox
 
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Default Re: 3e Nuke Design Rules

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Originally Posted by Fred Brackin View Post
No. Realistic nuclear weapon design would be excedingly complicated and make Homeland Security nervous.

I believe the 4e version of HT has some data on the Hiroshima and Nagasaki devices though modern warheads are much smaller.

You can get a _possibly_ accurate overview from Wikipedia. This has some things that have been generally known for some time. Such as critical mass sizes based on physics and soem important design features that are not really intuitive.

For example, after you get your basic nuclear warhead you can double yield by adding a "boosted phase". In a mdern warhead this involves injecting deuteriumand tritum gas into the hollow core of the warhead durign the arming process.There they will undergo fusion when the warhead is detonated and essentially double the amount of neutrons. What does this cost in terms of mass and $? Essentally nothing in mass and very little in terms of $ compared to the plutonium core.

Note that this is not at all what any version of the Gurps rules tell you. Those rules are designed for play balance and intuitive sorts of logic where more results cost more mass and more money in proportion to the increase in yield. That's not how real world nukes work.
The reason that I'm asking is due to the fact that 1) it's CnC Tiberium and by TibSun and later they tend to consider 100+kT as tactical nukes (from what I gathered) and 2) there isn't much I've been seeing in terms of nuke construction rules.

Though, to be honest, CnC Tiberium-verse's battlefield is basically a hop and a skip away from being something out of Bolo or Ogre-verse...
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Originally Posted by johndallman View Post
That warhead is way too powerful for submarine use. It will destroy the launching submarine via the shockwave, which is very powerful underwater. Historical nuclear torpedoes have had much less yield: the most powerful one deployed appears to have been the USN's Mark 45 torpedo, at 11kT, and using that was regarded as dangerous to the firer.
Well, the torpedo has a non-ASROC range of 150km and the ASROC version has a 33km range on top of the ASROC's 320km range...

... but I see your point.
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Old 02-05-2022, 08:13 PM   #5
Fred Brackin
 
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Default Re: 3e Nuke Design Rules

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Originally Posted by GURPS Fox View Post
The reason that I'm asking is due to the fact that 1) it's CnC Tiberium and by TibSun and later they tend to consider 100+kT as tactical nukes (from what I gathered) and 2) there isn't much I've been seeing in terms of nuke construction rules.

Though, to be honest, CnC Tiberium-verse's battlefield is basically a hop and a skip away from being something out of Bolo or Ogre-verse...

.
No,100kt isn't a tactical weapon but If the videogame isn't very realistic by contemporary standards your adaptation will probably survive Gurps rules of limited realism. Between cinematicism, limited real world research and possible advances in the future SOTA you might as well just make stuff up.
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Old 02-05-2022, 10:10 PM   #6
GURPS Fox
 
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Default Re: 3e Nuke Design Rules

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Originally Posted by Fred Brackin View Post
No,100kt isn't a tactical weapon but If the videogame isn't very realistic by contemporary standards your adaptation will probably survive Gurps rules of limited realism. Between cinematicism, limited real world research and possible advances in the future SOTA you might as well just make stuff up.
Then again, we're talking about a universe where ion storms can destroy nuke bunkers...

... I'll keep that in mind.
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Old 02-06-2022, 02:22 AM   #7
RogerBW
 
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Default Re: 3e Nuke Design Rules

Realistic nuclear weapon design rules for the 1990s onwards:

(1) Is the bpmb/missile/etc. big enough to contain a nuclear warhead at all?
(2) OK, how much boom do you want?
(3) You got it.

Also, see GURPS OGRE.
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Old 02-06-2022, 10:28 AM   #8
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Default Re: 3e Nuke Design Rules

Keep in mind that non-flexible and sealed DR is squared against explosions in 3rd, a the front armor on a modern MBT is going to have over DR 7,000,000 against a blast! Also in 3rd, blast damage for a nuke is quartered based on a falloff range that is double for every 10 fold increase in yield (it seems to be roughly 128yrds × yieldı/³ × 0.9), a 148kt device would have a fall off of ~583yrds.

Now for warhead weight, it doesn't really go into detail how to figure the weight of nukes. It does give the minimum diameter a warhead can so my only guess would be treat them as a normal sized warhead of the given diameter.

So assuming a TL 7 setting, a 100kt warhead will have a 150mm diameter which gives 200mm³/125,000 or 64lbs huh...based on actual thermonuclear nukes made during the 70's/80's (the newest nukes I can find any real data on), which tend to have ~ 0.3-0.4kt/lbs at the 100kt range (note this figure gets much more efficient the higher the yield with even fairly older megaton range weapons hitting 2 or more kt/lbs. Which makes sense, the smaller the yield, the harder it is for the fissionables to undergo critical mass) which would give us a weight between 250 and 333lbs. So yeah, I'd just look up real world examples and flavor to taste (for example if in your version of C&C real nuke development kept going into the 90's you could get away with decent reduction in mass, about a third reduction isn't unreasonable). I mean, this is what I do for guns I stat. I find the closest real world gun to size/energy of what I'm doing and just fudge the numbers based on design considerations till they look good. For a starting point, Atomic Rockets has some good data on nukes, I'd trust it over wikipeida heh.
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Old 02-06-2022, 02:47 PM   #9
GURPS Fox
 
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Default Re: 3e Nuke Design Rules

Quote:
Originally Posted by RogerBW View Post
Realistic nuclear weapon design rules for the 1990s onwards:

(1) Is the bpmb/missile/etc. big enough to contain a nuclear warhead at all?
(2) OK, how much boom do you want?
(3) You got it.

Also, see GURPS OGRE.
I'll have to get a copy of OGRE.

... and reasonable.
Quote:
Originally Posted by The_Ryujin View Post
Keep in mind that non-flexible and sealed DR is squared against explosions in 3rd, a the front armor on a modern MBT is going to have over DR 7,000,000 against a blast! Also in 3rd, blast damage for a nuke is quartered based on a falloff range that is double for every 10 fold increase in yield (it seems to be roughly 128yrds × yieldı/³ × 0.9), a 148kt device would have a fall off of ~583yrds.

Now for warhead weight, it doesn't really go into detail how to figure the weight of nukes. It does give the minimum diameter a warhead can so my only guess would be treat them as a normal sized warhead of the given diameter.

So assuming a TL 7 setting, a 100kt warhead will have a 150mm diameter which gives 200mm³/125,000 or 64lbs huh...based on actual thermonuclear nukes made during the 70's/80's (the newest nukes I can find any real data on), which tend to have ~ 0.3-0.4kt/lbs at the 100kt range (note this figure gets much more efficient the higher the yield with even fairly older megaton range weapons hitting 2 or more kt/lbs. Which makes sense, the smaller the yield, the harder it is for the fissionables to undergo critical mass) which would give us a weight between 250 and 333lbs. So yeah, I'd just look up real world examples and flavor to taste (for example if in your version of C&C real nuke development kept going into the 90's you could get away with decent reduction in mass, about a third reduction isn't unreasonable). I mean, this is what I do for guns I stat. I find the closest real world gun to size/energy of what I'm doing and just fudge the numbers based on design considerations till they look good. For a starting point, Atomic Rockets has some good data on nukes, I'd trust it over wikipeida heh.
... thanks for your input. One of the things I love about GURPS players is that they're more than willing to help.

As much as I hate Atomic Rockets' sheer pessimism, I'll have to go back and see what they have.

Though this is a TL9 setting that is mostly focused on Earth, you guy's help is doing a lot for me.
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Old 02-06-2022, 02:58 PM   #10
Anaraxes
 
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Default Re: 3e Nuke Design Rules

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Originally Posted by Fred Brackin View Post
No. Realistic nuclear weapon design would be excedingly complicated and make Homeland Security nervous.
And you thought the Secret Service was trouble.
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