Updated SATNUC

[The_Ryujin]

I've been working on a upcoming campaign that is going to be continuation of a test campaign I did with group of friends to help work out a home brewed RPG system I was working on until I came across GURPS and found it did almost everything my system was trying to but better (well that and the POS computer I had at the time corrupted all my game files and I didn't have any back ups, I was kinda tech dumb at the time and the stupid thing didn't have a working CDR or flash drive ports so I was pretty SOL heh). Basically I ended up giving up on the system and pretty much canceled the play test (without giving it a proper send off) and a few years later I was talking to my old group about gaming stuff and the campaign came up and to my surprise they all really liked it and wished they could start it up again so I decided to update it and run it as my first real full on GURPS campaign.

Of the many things I have to update from my system was a small amount of tactical mini nukes they got their hands on that could either fire in conventional or shaped charge mode (they were originally acquired as a means to to blow out the rector core of a warship that crashed on a lower tech level planet before a local power could use the down ship to bombard a neighboring country but they were crafty enough with their demolitions roll to take out the reactor without needing all of them and saved the left overs "just in case" heh). This of course was pretty much the same thing as a SATNUC but since they haven't been updated to 4th edition yet I figured I'd give it a try and post my results here both for if anyone was interested in using them for their own game as well for feed back on it.

SATNUC
First figure the warheads diameter in millimeters and it's TL.

Damage:
-Primary Plasma Jet: Does Warhead diameter × (Warheads TL+1) × 0.15 dice worth of burning explosive damage with the surge modifier and a 10 armor divisor.

-Linked Blast Damage: 6d× (10× (warhead diameter/80)^(2/3)) crushing explosive damage.
-Linked Thermal Pulse: 6d× (9× (warhead diameter/80)^(2/3)) burning explosive [1] damage with the surge and radiation modifiers.

[1] Divide explosive damage by only 2 × distance from center of the blast rather then by 3×.

Weight: 3.2 × (warhead diameter/80)^3 lbs.

Warhead Yield: 0.0001 × (warhead diameter/80)^3 kilotons.

Cost: $10,000 × (warhead diameter/80)^3

Soooo.... how did I figure this mess?

Well in 3rd edition it seems that a SATNUC skeet had a diameter of 80mm, weighed 3.2lbs, costed $10,000, did 6d×2000 explosive damage to the target and did 6d×200 to a "burst radius" of 48 yards so I used this as my "base". Also from it's blast damage I guesstimated the skeet had a warhead that was on par with 1/10th of ton of explosives.

Working with that base and starting with it's damage...

Since DR hasn't changed between editions I didn't need to update the penetration damage of the SATNUCs main attack that much, I just reduced the damage by a factor of 100 to 6d×20 and added a 10 AD to it. The reason for the 100 fold reductions was since according to the rules most targets DR was was going to be increased by 10 against it anyway so I just reduced the damage since the penetration was going to be the same and it made things easier. The other reason was that it made sense that it since it was still a type of shaped charge it would have a high AD so so I reduced the damage further and slapped the 10AD on it.

Now I just needed to figure out how to scale the damage since there were no rules that I know of to make bigger SATNUCS in 3rd edition so I looked up what info was available on the legendary Casaba-Howitser and found that, for the most part, it seemed to follow the same kind of rules that a normal shaped charge follows. Thankfully I figured out a while ago that in 4th GURPS stats how much penetration a HEAT round does based on the warheads diameter (which is true to real life) and the warheads TL (the full formula is warhead diameter × (warheads TL-1) for normal HEAT rounds, the TL modifier is reduced further for HEMP and self forging penetrator rounds) and figured out the above formula from there.

For it's blast damage I wanted something a bit more detailed the more abstract "burst radius" used in 3rd so i started with my assumption that the yield of a SATNUC was equivalent to 200lbs of TNT but do to the shaped charge effect the blast was only half as powerful and so I stated as a 100lbs explosive and then used the rules for how GURPS stats pure fusion bombs (This one, in so far as I can tell, can't be figured out by looking over stats so sadly I can't share the full details here) to figure out the actual blast damage thermal effects. Then I just use the same scaling factor Ultra-Tech used to scaled warheads.

Everything else was pretty easy to figure out from there.