[Spaceships] Armor Density

[DouglasCole]

Originally Posted by Anthony

All performance and stats are calculated based on the assumption of 20 slices that are equal in both mass and volume.

You keep stating this, but it was not David's intent. I was there for the writing AND the playtest, and you're just mistaken here.

The mass is an explicit calculation of equality. The volume is an admitted kludge for simplicity. Period.

[Anthony]

Originally Posted by DouglasCole

You keep stating this, but it was not David's intent. I was there for the writing AND the playtest, and you're just mistaken here.

So was I, and I'm not. The spaceships system is based on assuming that all ships of the same mass will have approximately the same volume.

[Crakkerjakk]

Originally Posted by DouglasCole

You keep stating this, but it was not David's intent. I was there for the writing AND the playtest, and you're just mistaken here.

The mass is an explicit calculation of equality. The volume is an admitted kludge for simplicity. Period.

Originally Posted by Anthony

So was I, and I'm not. The spaceships system is based on assuming that all ships of the same mass will have approximately the same volume.

Anthony's right. It's just an assumption that falls out of the math used in Spaceship's combat system. If you have an equal probability of hitting each of the systems (neglecting core), then they all have the same surface area exposed to be hit. Thus, the simplest assumption is that each segment not only has the same mass but also has the same volume.

Sure, it's a gamable abstraction, but what that abstraction ends up implying is that all systems have identical mass AND volume, even though you're only designing ships by looking at the mass.

[DouglasCole]

Requoting from the book:

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.

Mass, not volume. QED.

As I said, I agree that equal-surface area approximation seems logical due to the simplistic metagame desire to have a 1d6 roll for what section of hull is hit. However, it's explicitly a metagame and INCORRECT assumption based on the author's own statements.

You guys are taking literalism way too far.

[Langy]

Originally Posted by DouglasCole

Requoting from the book:



Mass, not volume. QED.

As I said, I agree that equal-surface area approximation seems logical due to the simplistic metagame desire to have a 1d6 roll for what section of hull is hit. However, it's explicitly a metagame and INCORRECT assumption based on the author's own statements.

You guys are taking literalism way too far.

The base Spaceships system ignores volume, true - but it does so by assuming every system has the same volume, and that's completely evident in the hit location rules (where systems have equal hit probability no matter if they're high-density armor or low-density hydrogen fuel tanks). It's an implicit assumption of the system, sure, but just because it's not explicit doesn't mean it isn't there.

You also seem to be forgetting that we're talking about an alternative design system here where differences in system volume are accounted for (at least in relation to armor). Nobody has been saying that the base system works by volume - just that it's relatively easy to rejigger the system so that it does account for volume as well as mass.

[Crakkerjakk]

Originally Posted by Langy

The base Spaceships system ignores volume, true - but it does so by assuming every system has the same volume, and that's completely evident in the hit location rules (where systems have equal hit probability no matter if they're high-density armor or low-density hydrogen fuel tanks). It's an implicit assumption of the system, sure, but just because it's not explicit doesn't mean it isn't there.

Exactly. It doesn't matter if the author says "I'm using normal arithmetic" and then proceeds to state that 1+1=3. He ain't using normal math. I understand that the hit location dealie is a gamable approximation. But the original point is that the hit location percentages are off using realistic densities for varying sections because all sections have the same probability of being hit.

The same mass of crew cabins and liquid hydrogen tankage will realistically have different volumes. But not according to the Spaceships hit location rules.

[Anthony]

Originally Posted by Crakkerjakk

But the original point is that the hit location percentages are off using realistic densities for varying sections because all sections have the same probability of being hit.

Also because DR doesn't vary with what modules you have.

[Dinadon]

Originally Posted by Crakkerjakk

Exactly. It doesn't matter if the author says "I'm using normal arithmetic" and then proceeds to state that 1+1=3. He ain't using normal math. I understand that the hit location dealie is a gamable approximation. But the original point is that the hit location percentages are off using realistic densities for varying sections because all sections have the same probability of being hit.

The same mass of crew cabins and liquid hydrogen tankage will realistically have different volumes. But not according to the Spaceships hit location rules.

No, they all have the same surface area in a given hull section. We aren't given anything to indicate that the front, center and rear sections actually divide the ship's volume or surface area up equally, but it will probably be close. We also don't have enough information about the core systems beyond the fact they are 5% mass.

In short, there isn't enough information provided to say anything about volume. However we can freely talk about surface area.

[Anthony]

Originally Posted by Dinadon

In short, there isn't enough information provided to say anything about volume. However we can freely talk about surface area.

Well, if we make the assumption that ship designs are rational, surface area will range from 4.84 to maybe 8 times volume ^ 2/3. Also, we know that streamlined ships have a surface area penalty, since they have lower DR, so we should probably assume that surface area for unstreamlined ships is pretty close to the 6 * v^2/3 used by VE2.

[terranstrider]

Mass vs Volume?
[Spaceships] designer notes re volume:

Notes for Deck Plans
GMs may wish to create deck plans for spaceships and space stations that follow the general design layout, with front, central, and rear sections divided into individual systems. Since spacecraft designs are based on their mass, the actual size of any system will vary somewhat due to differences in density. The table below shows the number of one-yard hexes per system:
Deck Plans Table
Hull Armor Other Systems
SM+5 neg. 2-3
SM+6 neg. 3-5
SM+7 0-2 6-15
SM+8 2-5 16-50
SM+9 6-15 51-150
SM+10 16-50 151-500
SM+11 51-50 501-1,500
SM+12 151-500 1,501-5,000
SM+13 501-1,500 5,001-15,000
SM+14 1,501-5,000 15,001-50,000
SM+15 5,001-15,000 50,001-150,000
Armor is "solid" spaceship hull. Cargo holds, fuel tanks, hangar bays, and open space systems will be 90% or more empty spaces, while habitats, and passenger seating will be 70-80% devoted to open space for the interiors of cabins, rooms, or corridors; the rest will be machinery. Factories will likely be about 50% machinery and 50% open space for assembly lines, etc. Most other systems will be 90% or more filled with machinery, with any remaining space devoted to rooms for workspaces, corridors, or ducts. One exception to the above are control room systems, in which (on larger vessels) most of the mass is distributed over the hull. A control room will generally take up at 3-5 hexes per control station; the rest of the mass is normally devoted to thruster and antenna systems outside the hull.

I interpret the above information as "go with what suits your campaign".
For example: a SM +10 ship (10,000 ton) in my campaign, streamlined wedge with 15% armour mass would maybe have 7000 cubic meters volume (no I cannot handle imperial measurements). This is all too complex for me so irrespective of the mass of systems, I have given 10 kiloton streamlined ships:
Volume: 10,000 cubic meters.
Length: 200 m
Hight: 12.25 m
Surface Area: 5,050 square meters

Sure I have old battleships massing 1 megaton the size of large freighters (100 kilotons) kicking about. However as the Spaceships combat system is totally irrelevant to any hostile encounter involving players (poof; you're vapourised), why bother with the "reality" calculations?
Just because I like it.
Really want a copy of GURPS Vehicle Design!