[GURPS Starships] Armor tweaks
 

A few days ago serendipity bit me and I came up with two simple and quick ways to tweak the protection provided by the armor systems listed in the GURPS Spaceships line in the hopes that they will lessen the eggshell feel of it and figured might as well share them on the forum for all that are interested.

Armor of Quality
The Spaceship series makes the assumption that the hulls of ships are going to be covered in lower end armor to keep costs low which in turn is part of the reason why dDR in those books are generally so low for a given TL. Now this is over all a reasonable assumption since, for the most part, even modern day real world warships don't use the highest grade plate available but this isn't always the case both in reality and fiction.

A good fix for this is take how Spaceships already handles armor and tweak it a bit:

Assume that the RAW armor values represent good, but not the best quality version of the given material.

Fine quality armor gives 1.5x the listed amount of dDR but costs 5x as much- It gives as much protection as armor as the average armor of the next TL up but costs more since it's not as easy to makes give the current TL's technology.

Very Fine quality armor gives 2x the dDR but costs 20x as much for the same reasons.

Ships that have need for some protection but not long term protection or simply desperate captains can make due with Cheap quality armor. Divide dDR by 1.5 and cost by what should be 1.5 in most cases but use the cost of a same sized armor one TL less if cheaper.

Note in most cases round numbers to closest progression on the SSR table (i.e. 10, 15, 20, 30, 50, 70 and so on) to get figures close to RAW if you want.

For example: SM +11 US TL11 Diamondoid armor gives dDR100 and costs $300M. Fine quality Diamondoid armor would give dDR150 but cost a whopping $1500M! Very Fine Diamondoid armor would give dDR200 but cost an even more staggering $2100M. On the other hand Cheap quality Diamondoid armor would give only dDR70 (67 rounded up) but only cost $150M (since that would be better then the $200M given by dividing by 1.5).

Armored Belts
Another way to add better protection to a ship without upping the cost to much is to lay better or simply just more armor in belts over only the vulnerable spots on a ship.

To add belts to a ship just select a armor system of choice but instead of it covering the full ship you instead get 6 "belts" to divy up between a sections systems that only protect the given system if hit by an attack.

For Example: You are designing a SM +10, TL10 armored cruiser and deicide to give the center section a belt armor system and then to give 2 belts each to the ships control center, reactor (a core system) and the a cabin systems located there. If the ship is attacked, only these sections will receive any protection if hit unless you take another armor system.

Each belt gives a system dDR equal to the amount that the chosen system normally gives x the number of belts you gave it on top of the dDR given by any other armor systems you decide to add. It also increases the amount of Radiation PF someone in a given system gets, treat each belt you give as a an extra system worth of PF but only for that system (belt armor only gives as much PF to the full ship that a normal armor system would give).

For Example: To continue from above, let's say the armor chosen is (good quality) TL10 Nanocomposite armor, this would give each of the choosen systems 2 x dDR70 or dDR140 against attack on top of any other full armor systems added. Anyone inside any of those systems would receive 2x more PF as well (this lends it's self well for making storm shelters).

Note that you CAN give armor to com and sensor systems but realistically I would limit it to no more then 1 belt for each system. You also can give belts to core systems, this will help make then good storm shelters.

Another thing to note is that if you choose a smaller armor system to be turned into belts you still get 6 belts, they just give less dDR and PF per belt (for example a half system of armor would give only half as much dDR and PF per belt).

Alright guys, hope you find these tweaks usefull. Any questions, comments and error findings are welcome as well as any Starships tweaks you might have yourself that you would like to share.

Re: [GURPS Starships] Armor tweaks
 

Comments:
Very Fine armor should probably cost more than 7x. At 7x it is almost exactly the same $/DR as Fine armor. EDIT: I'd suggest 20x. You pay really big at the cutting edge.

The rules you give for cheap quality armor amount to simply 'use armor of the previous TL', which is already the usual way of getting cheap armor. Each armor generation raises cost by the cube root of 10 (which is more than 2x) and protection by the sixth root (which is pretty close to 1.5x). Your rules add a model for cheap organic armor, but other than that they're redundant.

Assigning armor 'belts' to core systems is a bit weird, considering that they're internal and it is impossible to target them directly. Maybe meaningful, mechanically feasible, but weird. It also makes no sense to forbid belt armor on sensor arrays considering that regular armor does protect sensor arrays.

Re: [GURPS Starships] Armor tweaks
 

The "armor belts" thing needs one serious tweak: it shouldn't give 20 belts, it should only give 6, just like a normal armor system. Giving 20 belts per system means that you get the protection of three and a half systems of normal armor for the weight of only one. That's kind of broken: there's no good reason to take normal armor when you can just use armor belts and get so much more mileage out of it.

Well, except for sensor systems, but then this rule makes for the odd situation where you can apply armor that covers sensors, unless that armor only covers sensors.

I think a better system would be to treat armor as normal, but when you're all done, you can shift some or all of the DR from each armor system from one hit location to another within the same section of the ship (Front, center, back).

For example, say that you've got one armor system giving dDR 70 over the section it's on. You could visualize this as protecting each of the six locations separately: 70/70/70/70/70/70. But say you really want to protect that first location, so you shift 20 dDR from the other locations (Nearly 30% of the armor mass in those areas) and apply it all to the location you want to protect. Now it looks like 170/50/50/50/50/50. The first location is heavily protected, while the others are somewhat less so, but you still have the same amount of total armor. It'll take a lot more firepower to take out that first location, but because of the weaker armor elsewhere, the total durability of the ship has gone down slightly.

Re: [GURPS Starships] Armor tweaks
 

Based partially (in terms of effect) on the DR progressions from Vehicles, my own version has Cheap (-1 TL) as 1/3rd price, Advanced (+1 TL) as 3x price, and Top of the Line (+2 TL) as 10x price. For Space Opera, I've also allowed for Optimized armor (+1 TL against one of Cr, Cut/Pi, or Burn; -1 TL against the others) and Ablative armor (+1 TL, armor is semi-ablative), both of which cost the same as normal armor (and can stack with Quality and each other).

I do like your idea of "armor belts," although the math needs work (or maybe I'm just misreading). The way it looks now, someone could buy an Armor Belt system and use 3 belts on 4 and 4 belts on 2 of the systems in that hull section for 3x or 4x dDR on that entire hull section. Each Armor Belt system should instead give you 6 belts, with the same effects as now.

Honestly, one thing I think has been suggested before and makes a good deal of sense (most armor is so dense compared to the rest of the ship that it will take up effectively zero volume) is to actually design vessels without armor, then add on the armor (and downgrade performance of engines) later. So you might start with a design like this:

Front Hull
[1] Spinal Battery
[2-4] Major Batteries
[5] Tactical Array
[6] Defensive ECM
[core] Control Room
Central Hull
[1] Spinal Battery
[2-4] Tertiary Batteries
[5] Antimatter Power Plant
[6] Defensive ECM
[core] Spinal Battery
Rear Hull
[1-4] Fuel Tanks
[5-6] Fusion Torches
[core] Antimatter Power Plant

At TL10, it would have 1G acceleration and 60 mps delta-V. You'd then toss on armor as you see fit - 6 systems might be divided up as 3 in the front, 2 in the center, and 1 in the rear, and would increase the ship's mass by 30%, thus dropping acceleration to 0.77G (1/1.3) and delta-V to 46 (60/1.3). This adds complication but can make it easier to design the ship you want without having to give up as much protection, and also gets rid of the oddity of hitting the armor system (what does that even mean?). Combined with your armor belts idea, you could improve the dDR of individual systems on their own - each system-specific piece of armor would add 0.17% (1/6%) to vessel weight, be 1/6th cost of a "full" armor system, and give full dDR to that one system.

Re: [GURPS Starships] Armor tweaks
 

That actually sounds does sound better. I'll go edit that in.

True, I just put it in for completeness sake for more reasons then not and they do have a use for Organic armor so I'll leave them in.

The core opition is there both to make storm shelters since the PF doubling would still be in effect as well to give an extra level of detail if wanted. As for the com's and sensors I probably should of said only one belt can be added since in reality they are hard to armor without interfering with their ability to function but I think I'll change that to a suggestion rather then a rule. Outside of that do think the belt armor rules work well?

But anywho, thanks for the feed back man. Made for good food for thought.

EDIT
Thanks Phoenix Dragon! I had a total brain fart with putting up 20belts per system! Yes they should be 6 and I just fixed it.

This is why I love this forum, all you guys rock.

Re: [GURPS Starships] Armor tweaks
 

A hit that expends itself gouging away large chunks of armor rather than boring into the enclosed systems? Probably a bit unlikely, given the volumetric consideration...but may be made more likely by armor design trying to redirect incoming energy into the (ultimately expendable) armor substance rather than the important bits.


However, giving up the 'systems as mass' concept is a pretty dramatic step.

Re: [GURPS Starships] Armor tweaks
 

@Varyon: I'm liking your add armor after the fact idea, as you said it does add some math but over all if math doesn't scare you I think it does pay off by giving less of a headache from having to juggle systems. As for the pricing of advanced armor, what I put is just my 2¢. Change as ya wish heh. Also yeah, I made a goof up with number of belts. For some reason numbers got crossed in me brain meats and I didn't notice it farting out nonsense.

Re: [GURPS Starships] Armor tweaks
 

It's not giving that up, it's essentially just building the ship like it were a character and then tossing a suit of armor on it. All mass is still accounted for - if my example were an SM+10 spaceship, the initial design is for a 10,000 ton vessel. Those 6 armor systems weigh 500 tons each (5%), so we're adding in 3,000 tons, for a 13,000 ton vessel. It's just that we're ignoring the extra weight of the armor when determining volume - and as long as we aren't using ice armor, this is probably close enough to accurate.

Yeah, I'm still torn as to what is the fairest price. Something like 4x for TL+1 (every +1 TL is x2 price; getting something 1 TL early is double cost) and 20x for TL+2 (every +2 TL is x5 price; getting something 2 TL's early is quadruple cost) corresponds more closely to RAW. My own system is meant for a Star Wars like Space Opera setting, so take it as you will.

Re: [GURPS Starships] Armor tweaks
 

I didn't say you were failing to keep track of the ship's mass. But the ship is no longer divided into 20 systems, each 1/20th of its mass. It is divided into 20 systems, each 1/20th of some particular mass, and then some variable number of additional armor systems of the same mass.

(Minor note you probably already realize: for calculating delta-V you have to reduce effective fuel tanks before bonuses for high fuel fraction, not just calculate delta-V and modify that. Your example ship had little enough fuel that this had no effect.)


Alternate Spaceships in Pyramid 3-34 offers another way of adjusting for the density of armor, and similar ideas on that subject had been worked with on the forums.

Re: [GURPS Starships] Armor tweaks
 

There are reasons to suppose that spaceship armour might not consist of solid slabs of strong material the way that the armour of ships and tanks does. Material strength is almost irrelevant when energy densities grossly exceed the energy density of chemical bonds. In protecting space probes and orbital facilities from hypervelocity impacts it is found to be vastly more cost-effective in terms of mass to use a "Whipple shield" or "meteoroid bumper" that is deliberately made of a material not stiff enough to support destructive shock waves and that is supported at some distance from the pressure hull. The gap in this variation on standoff armour allows room or time for the jet of material from the outer-skin impact to spread out and cool off. Whipple shielding consisting of a 1.3-mm soft aluminium bumper on 200mm spacers would be about 18 kg per cubic metre, which is denser than air but probably not as dense as generator, engines, full propellant tanks, or perhaps even cabins. Multi-shock shields and stuffed shields would be a lot denser, but not as dense as steel.