[Spaceships] Armor Density

[Dinadon]

Originally Posted by Anthony

Modules are based on both mass and volume -- the reason you can only fit X modules in a SM +Y hull is because of volume, not mass. The mass of the modules is handled by the change in performance.

That doesn't sound like Spaceships, since it's always 20 systems regardless of SM.

[RyanW]

I've added some modifications for lighter systems.

[Anthony]

Originally Posted by Dinadon

That doesn't sound like Spaceships, since it's always 20 systems regardless of SM.

Nah, spaceships is just X=20.

[Mark Skarr]

Originally Posted by Anthony

Modules are based on both mass and volume -- the reason you can only fit X modules in a SM +Y hull is because of volume, not mass. The mass of the modules is handled by the change in performance.

Originally Posted by Anthony

Nah, spaceships is just X=20.

No, that's not true. Each system is 5% of the ships total mass. It abstracts volume.

Originally Posted by GURPS Spaceships, pg 5

Spacecraft hulls are divided into three sections: the front hull, the central hull, and the rear hull. Each represents one-third of the spacecraft’s total mass (not volume). This need not be taken too literally: the actual shape may be more complex, e.g., “the front hull section” could include forward- facing parts of the vessel that are actually part of multiple different subhulls, pods, or wings.

The front, center, and rear hulls each contain six hull systems numbered [1] to [6]. In addition, two of the three hull sections contain deep- buried systems designated [core]. Each system is a major component. The numbers are used for hit location rolls (see p. 61), while the core systems are similar to the vitals location of a human. Each spacecraft has 20 systems, each 5% of the total mass.

Emphasis from book.

[dynaman]

Originally Posted by Mark Skarr

No, that's not true. Each system is 5% of the ships total mass. It abstracts volume.

Emphasis from book.

All that needs to be done is take the extra systems and divide the speed by it. If the ship ends up being 30 modules then the speed will be X

X = (given speed from spaceships) / 30 times 20.

For low volume system like armor (and considering how coarse the spaceships systems are already) this works fine. (I also tend to ignore hits on extra armor systems in this case)

Ships still only get two core modules as well.

[Langy]

Anthony's method should work fine. The only reason ships are restricted to 20 locations is due to the effect ship mass has upon performance (which is mostly fixed adequately by modifying performance by the total number of systems used, except for fuel tanks, which would need to be reworked a bit more) and for reasons based upon volume. If you alter the ship performance based upon total number of modules, you've got a system that needs 20 systems for volume-based reasons (such as number of people that can fit in a hull section or the hit location rules), not mass.

You could expand it so that different systems took up different amounts of volume slots while taking up one mass slot. Armor modules would take up 1 mass slot and 0 volume slots, habitats might take up one mass slot and two volume slots, etc.

For fuel tanks, the fuel tank multiplier would need to be based upon the actual fraction of fuel tanks to total mass slots used. Everything else should work fine.

[RyanW]

Originally Posted by Langy

Anthony's method should work fine. The only reason ships are restricted to 20 locations is due to the effect ship mass has upon performance (which is mostly fixed adequately by modifying performance by the total number of systems used, except for fuel tanks, which would need to be reworked a bit more) and for reasons based upon volume. If you alter the ship performance based upon total number of modules, you've got a system that needs 20 systems for volume-based reasons (such as number of people that can fit in a hull section or the hit location rules), not mass.

That way works, but is a completely different design system from Spaceships. It's similar to how it was done with the various 3e modular vehicle design systems. A hull of a given size has a given number of spaces, and you calculate mass and performance last.

The problem I see with this idea is one that haunted all of the 3e systems: It's difficult to build a vehicle with a target performance. Basing everything on same-mass modules means that each module give a certain performance (3G for an engine, 12 mps dV for a fuel tank), rather than having to calculate performance at the end.

[Ulzgoroth]

Partitioning spaceships into a different number of systems breaks the Spaceships damage system.

Everything else you can work around if you're willing to do the math, but how do you deal with that?

[Anthony]

Originally Posted by RyanW

The problem I see with this idea is one that haunted all of the 3e systems: It's difficult to build a vehicle with a target performance.

This is true, but the fewer variants you have, the easier it is. If just armor has nonstandard volume, it's actually pretty easy to come up with target performance (adding fuel and habitat makes it messy rapidly).

[Anthony]

Originally Posted by Ulzgoroth

Partitioning spaceships into a different number of systems breaks the Spaceships damage system.

Everything else you can work around if you're willing to do the math, but how do you deal with that?

By not assigning damage locations to extra armor?