GURPS Spaceships, upscaling sizes

[Rolando]

Using passenger seats will be a better representation of having a space someone can lay down for a while, like the beds in an RV.

It allows for 1 bed per module in a SM+5 ship. So instead of using 3 modules to have a 2 persons habitat you may have 3 beds.

But you will only have 24 hours life support.

P.D.: The life support limit is setting dependent though, as in some settings a small fighter have more than 24 hours of air...so you may declare that passenger seats and control rooms have total life support, for air at least.

[Phantasm]

Originally Posted by Rolando

Using passenger seats will be a better representation of having a space someone can lay down for a while, like the beds in an RV.

"Radar repaired, sir. We're picking up the outline of a Winnebago."

Sorry (not sorry; never apologize for Spaceballs)... But that's about the right size, given most RVs can run SM +4 (the really small ones with a single bed over the driver compartment) to +6 (larger bus-sized Class B/E* (depending on locale) types). If using "Alternate Spaceships" from Pyramid #3/34: Alternate GURPS, the bulk of the Middle and Rear sections are probably a Habitat regardless of what Spaceships says, but said Habitat would take up something like 10-12 modules, using the rules for oversized modules (I think they're in SS4 or SS7).




* In South Carolina where I am, the Class B and Class E cover the same weight class, more than 26,000 pounds/13 tons gross weight, equivalent to a bus, large RV, or large cargo truck without a trailer; the B is the CDL license, while E covers non-commercial stuff of the same weight class. A and F are for the semi-trailer types, commercial and non-commercial respectively. Some states require a Class B license (CDL certification optional) for the larger bus-sized RVs.

[Fred Brackin]

Originally Posted by Phantasm

"Radar repaired, sir. We're picking up the outline of a Winnebago."

Sorry (not sorry; never apologize for Spaceballs)... But that's about the right size, given most RVs can run SM +4 (the really small ones with a single bed over the driver compartment) to +6 (larger bus-sized Class B/E* (depending on locale) types).

* In South Carolina where I am, the Class B and Class E cover the same weight class, more than 26,000 pounds/13 tons gross weight,.

Sorry,,this may be one of those things that I need to not sound condesceding about but in Spacewships terms SM+6 needs to be (at least round up to) 100 tons. 313 tons is already roundign up substantially to sM+5 (60,000 lbs or 30 tons).

I _know_ the chart in Characters has SM+6 being from over 15 yards up to 20 yards and if not using Spaceships you can have that SM+6 bus but unfortunately Spaceships takes the same technical term ("SM+") and uses it for a completely different meaning.

Spaceships SMs are entirely mass-based. They have to be to make the Delta-V calculations work out right (for what's already a loose-ish defintion of "right").

<shrug>Maybe your 26,000 lb SM+6 space-going RV. is bigger on the inside than the outside. It would need to be for each system devoted to cargo to carry 10,000 lbs or 5 tons.

I hope this hasn't come off as condescending. It really is unforunate that Spaceships has taken a term from the Basic set and changed its' meaning when used in Spaceships. As a playtester for Spaceships I can only plead that I overlooked this. My use of the Basic SM for vehicles had been quite casual. Now that I think of it Ve2 assigned an SM to finished vehicle desings but I never checked if that was completely compatible with the Basic set "longest dimension" method. It would have been quite difficult to come up with a hard and fast longest dimension in any even partly mass-based system (Ve2 tracked both mass and volume though volume was more sketchy being determined by assuming a standard density for various types of components..

[Phantasm]

Originally Posted by Fred Brackin

Sorry,,this may be one of those things that I need to not sound condesceding about but in Spacewships terms SM+6 needs to be (at least round up to) 100 tons. 313 tons is already roundign up substantially to sM+5 (60,000 lbs or 30 tons).

I _know_ the chart in Characters has SM+6 being from over 15 yards up to 20 yards and if not using Spaceships you can have that SM+6 bus but unfortunately Spaceships takes the same technical term ("SM+") and uses it for a completely different meaning.

Spaceships SMs are entirely mass-based. They have to be to make the Delta-V calculations work out right (for what's already a loose-ish defintion of "right").

<shrug>Maybe your 26,000 lb SM+6 space-going RV. is bigger on the inside than the outside. It would need to be for each system devoted to cargo to carry 10,000 lbs or 5 tons.

I hope this hasn't come off as condescending. It really is unforunate that Spaceships has taken a term from the Basic set and changed its' meaning when used in Spaceships. As a playtester for Spaceships I can only plead that I overlooked this. My use of the Basic SM for vehicles had been quite casual. Now that I think of it Ve2 assigned an SM to finished vehicle desings but I never checked if that was completely compatible with the Basic set "longest dimension" method. It would have been quite difficult to come up with a hard and fast longest dimension in any even partly mass-based system (Ve2 tracked both mass and volume though volume was more sketchy being determined by assuming a standard density for various types of components..

That's alright. But permit me to explain my reasoning a bit: RVs are generally elongated boxes, giving them a +1 to SM that way above what their longest dimension/mass would be, it seems. I tend to round to the nearest rather than always up, so that 13 tons rounds to 10, or SM +4 by SS rules, and then +1 from elongated box on top of that to make +5.

But YMMV of course.

[Varyon]

Originally Posted by Fred Brackin

I _know_ the chart in Characters has SM+6 being from over 15 yards up to 20 yards and if not using Spaceships you can have that SM+6 bus but unfortunately Spaceships takes the same technical term ("SM+") and uses it for a completely different meaning.

Personally, I feel Streamlined should make the target -1 to target from the front or rear (effective -1 to SM) and +1 to target from the sides (and a spaceship would have 4 sides). That would probably describe that SM+6 bus better - it's SM+5 by mass, SM+4 to target from the front/rear, SM+6 to target from the sides.

Spaceships also makes Habitats and similar denser than they should be IIRC - compared to GURPS: Classic Vehicles, most of them have half the capacity for their weight, but their approximate size is about right. Arguably, they should have double the capacity but count as High Volume Systems - easier to target, and having too many reduces the effects of armor and can even boost the ship's SM for purposes of targeting it (basically the opposite of the optional Armor and Volume rules from Pyramid; in fact, you'd probably subtract the number of High Volume Systems from the number of Armor systems - or High Density Systems if you allow for others that have comparable density to armor - when using those rules).

[Fred Brackin]

Originally Posted by Phantasm

p, so that 13 tons rounds to 10, or SM +4 by SS rules, and then +1 from elongated box on top of that to make +5.

But YMMV of course.

Spaceships rules theoretically always round up. They also aren't modified by shape. It really might have worked out easier to deal with if Spaceships numbers were "SZ" or something like that.

[Rupert]

Spaceships' SM works at the same level of everything else - 'very roughly'. It assumes that the spaceship's overall density averages out much the same regardless of what the ship is composed of.

Habitats' lower than average density would be balanced out by some other component (a rocket for example) with a higher than average density. The really dodgy systems for this are armour (which has that optional rule dealing with it), fuel tanks for some (but not all) types of fuel, and some types of open spaces.

For short-term accommodation that's more than just a fancy chair, I came up with this:

Some thoughts about seats, and life support for small spaceships, using Spaceships:

From Spaceships 7, etc. we know that half the mass of a cabin, etc., or a passenger seat is the life support, and the other half is the fittings (seats, beds, etc.).

A habitat space masses either 8.333 tons or 7.5 tons (I think we can assume that the SM+6 habitat at one space in 5-tons is simply generous rounding, and as flavour text I write cabins in SM+6 ships as being unusually cramped). I'll go with a rounded average of 8.0 tons for cleaner maths.

A passenger seat masses 0.8333 tons or 0.75 tons, or 1/10th as much as a habitat (so about 0.8 tons on average)

So, given that a bunkroom fits four people into one habitat, and half of that is life support, a minimal indefinite recycling system for air and water masses (8.0 / 4) / 2 = 1.0 ton per person.

Also, half a passenger seat is limited life support (24 hours of air and water), and masses 0.8 / 2 = 0.4 tons.

Therefore, if you want a trip that takes longer than 2.5 days, you shouldn't use limited life support. Under that, and you should.

Unfortunately, the rules for No Life Support for seats and cabins do not reduce the price of them, so there's no guidance as to the cost of life support. I'd be inclined to just use the same price per ton for the fittings and the life support, for simplicity.

This makes limited life support mass 0.4 tons per man-day and cost $2,500 per man-day ($6,250/ton). The seat itself costs the same.

Full life support masses 1.0 tons per person, and costs $20K per person (and also $20K per ton). A single bunk costs and masses the same.

This means that a passenger seat, plus fairly spartan full life support, masses 0.4 + 1.0 = 1.4 tons, and costs 2,500 + 20,000 = $22,500, which we may as well just round to 20K to make the table nice and tidy (we'll just assume that the seats are basic, and the mini kitchenette and toilets are *really* basic).

Here's a table of these seats in spaceship systems:

Long-term Passenger Seating:

SM         +5     +6     +7     +8     +9     +10    +11    +12    +13    +14    +15
Seats       1      3     10     30    100     300     1K     3K    10K    30K    100K
Workspaces  0      0      0      0      0       1      3     10     30    100    300
Cost ($)   20K    60K   200K   600K    2M      6M     20M    60M   200M   600M    2B

A SM+4 ship will need to use three systems per seat.

We can also say that adding long-term life support to a Control Room costs 20K per station, and requires 1.0 ton of mass, probably in a habitat system (because they're easy to cut up).

[Ulzgoroth]

Originally Posted by Phantasm

Also note that Passenger Seating says that you can replace two seats with a stretcher (or similar-sized bench/cot), which would probably work for your purposes, if all you're looking for is a place for someone to lay down for a few hours while the ship drifts through space/is on autopilot.

I suspect this ship is meant to have full life support, rather than 24 hour limited life support, so it needs to pay Habitat rather than Passenger Seating rates. (Or something like Rupert's hybrid there.)

[Tyneras]

Originally Posted by Phantasm

That's alright. But permit me to explain my reasoning a bit: RVs are generally elongated boxes, giving them a +1 to SM that way above what their longest dimension/mass would be, it seems. I tend to round to the nearest rather than always up, so that 13 tons rounds to 10, or SM +4 by SS rules, and then +1 from elongated box on top of that to make +5.

But YMMV of course.

GURPS Spaceships handwaves away the different silhouette SMs for spaceships, which I think is a good decision the majority of the time. I figure it's best to just imagine a GURPS spaceship as a lump of clay with a set density, mass and volume you can mold into any arbitrary shape.

If you start changing that density, I recommend Pyramid #3/34 Alternate Spaceships.

So when trying to model something like an RV, go with mass and the boxy shape becomes just a special effect. You should remember to include it if you're using GURPS Spaceships to model things you plan to use in the standard system, tho. I did this to design a few tanks and transports.

[Rolando]

Also remember the spaceship construction is a tool and not even rules are mandatory.

if you need your space RV to have full life support at SM+5 do it. Say air recycling is advanced in your space setting and it can be made a lot smaller, up to be able to use it for SM+5 (or smaller if you need to). So passenger chairs and control stations have full life support, not just 24 hours.

Just as everything else in a sci fi setting the GM must define what is and what isn't available or possible.