GURPS Space GURPS Math

[Ulzgoroth]

Originally Posted by whswhs

What I think might help is a simple step by step "This is how I design this particular simple spacecraft," with page references. I have no idea where anything is in the book, or how to find it, or what order I'm supposed to find it in.

As far as ship design, there hardly are any pages to reference. You read page 8 (or page 5) where it tells you there are 20 systems in a ship in three sets of six and two [core]s, go through the hull size bit on page 9 to choose an SM, and then there's one big list (p9-28) that you pick systems from to fill your 20 slots.

Once you've done that, it's a ship. p34-35 calculate a vehicle stat-line for it. The remaining half of the book is rules for how to use it.

EDIT: There is no general procedure for filling out the design. One pattern that's sometimes suitable, though, is to design propulsion first. Decide what thrust and delta-V you'll need, pick drives (p21-24), add any reactors needed to power the drives, add fuel tanks until delta-V meets requirements. After that, check how many Systems you have left over, and determine what SM your ship has to be in order to fit the load you want into those spots.

[Mailanka]

Originally Posted by Warden

Not sure if it is GURPS Space but I remember flicking through one GURPS supplement to do with sc fi and it left me utterly baffled. I think it actually was rocket science the book got into in some parts. I understand GURPS tends to simulate our earthly physics (for the most part), but for the longest time it turned me off GURPS.

Do you sometimes labour under the number crunching that GURPS sometimes requires? I struggle with math, always have, so I was wondering if anyone else out there had the same math issues as myself and what they did to overcome that?

I've always thought a little pdf supplement showing what calculations GURPS requires in places (square roots, algebra, working out percentages/fractions etc) and how to perform those calculations would be very handy for those who struggle with number crunching. I know GURPS has examples, but if you just don't have any base from which to work from they don't help much if you have no idea what's going on from the get go.

A couple of things. First, none of that stuff is required. Do you know how Star Trek created their worlds for their TV show? They just made them up. "Ooo! Tantalus 4 will be a volcanic planet covered in this layer of smoggy clouds that blots out the sun! That sounds awesome!" Gravity? Same as Earth. Breathable atmosphere too because... reasons. Also! Strange alien space ruins! Awesome! At no point did they need to check out something like GURPS Space and perform esoteric mathematic calculations to gain permission to do this. They just did it.

Now, I would go through the esoteric mathematical calculations not because I felt I needed to, but because I was curious. How does one realistically get a world like this? The answer may well be "You can't," or it may also be that it's artificial, or it must necessarily be the result of a war, or what have you. I often found that my well-designed worlds and aliens and vehicles made sense in a larger context, and that was nice. My players found that pleasing. But it's not like Star Trek's wild and wooly approach lacks fans, right?

You don't need to do the math, but you can if you want to.

As for your final request, "cheat sheets" on how to do math are found all over the internet. If you are arithmophobic (afraid of numbers), then it will take more than a quick reference in a GURPS book to get over that. The truth is, you need more than the ability to use a calculator to make use of "advanced formulas" of GURPS. You need to understand what math is and what it is for.

For example, I had a friend who simply tried to walk through GURPS vehicles to design something from, I think, Robotech. Unsurprisingly, he got nonsense out the other end, because Robotech is not exactly grounded in hard sciences. But more importantly, he just started at the beginning and walked to the end and just guessed at things along the way. I had much better results because I didn't follow "the flow" of the book. I took what I knew (the size of the vehicles in question, the amount of damage their guns did, how long they endured, how swiftly they moved, etc) and fiddled with the formulas until I made the things I wanted to fall out fall out. Where numbers couldn't add up, I knew I had to hunt for more interesting solutions ("Obviously I need cosmic power here if I want to get a gun that does that much damage on so small a scale!") or make compromises ("Look, you just can't be that agile at those speeds. I'll tone down the speeds a little and the ranges and bring things a little closer together. That makes more visual sense anyway"). But the point is that you make the numbers work for you. You do not work for the numbers.

Which is why some people like me want VDS so bad, not because we can't build vehicles without it (A sci-fi plasma tank? It's like a normal tank, except with a plasma cannon on top. It has the sort of DR necessary to deal with plasma blasts and otherwise it mostly looks like an Abrams, whose vital information you can crib from Wikipedia. Done), but because we want to understand the underlying numbers and realities necessary to get to those vehicles. David Pulver once called it the "tech infrastructure book," and that's exactly right.

The same applies to planets: You use the detailed planetary creation to figure out how to create certain results and what their implications would be (that resource rich planet is probably volcanically active. Can you have a habitable moon orbiting a gas giant? What about the radiation? What about the "eclipse" moment when the gas giant is between the moon and the sun? Is the gas giant a super-hot giant? Did it move into the inner system recently? Is there chaos in the inner system now? Does that mean we have regular meteor showers on the planet?)

A really good way to practice this, incidentally, is with the alien creation system. It doesn't involve complex math, but it does require you to take these out-of-order steps if you want to get the results you want. How do you make a paranoid species? What is the result of a predator species loaded to the gills with claws and fangs and a bony carapace and a killer hunting instinct? Can hive-mind creatures be sapient? What does that look like? You just plug the results you know you want into places, and then work backwards (to see what is necessary to get the results you want) and forwards (to see what the implications of your choices are)

That's the real trick to using these systems in GURPS, not "knowing the maths."

[Peter Knutsen]

Originally Posted by whswhs

You know, this is kind of weird, I admit, but I've never been able to make any sense of the Spaceships design rules. I just look at them and I can't imagine how to do anything with them. I had to struggle with the Vehicles system, and there are things in it I find problematic, but it made sense to me in a way that Spaceships doesn't.

I, on the other hand, figured out all of the basics merely from the "leak" that was posted on here, showing that it designed spaceships of consisting of 3 "sections" each of 6 "modules", plus two "core" "modules" which must be in different sections.

I immediately saw how that handled system damage determination, or "hit location" if you prefer that term (I could infer that you'd roll 1d6 to determine which module got damaged in any given section, although I did not know for sure whether you first rolled 1d3 to determine section randomly or if section was deterministic), and also saw that the system was mass-based rather than volume-based to facilitate the realistic determination of the performance of reaction mass drives (e.g. how much delta-V does this beast give me, relative to how much is required to get from Mars surface to Mars orbit?).

It just clicked for me. Weeks if not months before the PDF was actually put up for sale.

[Peter Knutsen]

Originally Posted by Mailanka

For example, I had a friend who simply tried to walk through GURPS vehicles to design something from, I think, Robotech. Unsurprisingly, he got nonsense out the other end, because Robotech is not exactly grounded in hard sciences. But more importantly, he just started at the beginning and walked to the end and just guessed at things along the way. I had much better results because I didn't follow "the flow" of the book. I took what I knew (the size of the vehicles in question, the amount of damage their guns did, how long they endured, how swiftly they moved, etc) and fiddled with the formulas until I made the things I wanted to fall out fall out. Where numbers couldn't add up, I knew I had to hunt for more interesting solutions ("Obviously I need cosmic power here if I want to get a gun that does that much damage on so small a scale!") or make compromises ("Look, you just can't be that agile at those speeds. I'll tone down the speeds a little and the ranges and bring things a little closer together. That makes more visual sense anyway"). But the point is that you make the numbers work for you. You do not work for the numbers.

Which is why some people like me want VDS so bad, not because we can't build vehicles without it (A sci-fi plasma tank? It's like a normal tank, except with a plasma cannon on top. It has the sort of DR necessary to deal with plasma blasts and otherwise it mostly looks like an Abrams, whose vital information you can crib from Wikipedia. Done), but because we want to understand the underlying numbers and realities necessary to get to those vehicles. David Pulver once called it the "tech infrastructure book," and that's exactly right.

One thing that GURPS Vehicles does, and GURPS Spaceships, but which isn't done by BESM or by my "point-based spaceship system", is that they take input in the form of Tech Level and monetary budget, and based on that limit how much vehicle you can get.

In BESM, or my own little hack, you just get a pool of points to spend.

This means that yes, you do get the tradeoff effect, that e.g. if you want more armour you'll have to "sell down" something else, but at no point does monetary cost enter the equation. You can't ask either system questions like "how much spaceship can I get for 15 billion dollars?" or "but what if I have 30 billion instead?". Nor can you ask "in which ways are the spaceships of the TL10 Sirians better than the spaceships of the TL8 Earthlings, and by how much?"

GURPS' systems tend to be tied to the world, and to take real-world parameters as input (vehicle size, e.g. tiny fighter size vs. huge kilometer-long ship, is another parameter, although that actually is included in my system, in a simplistic way. And perhaps in BESM2 as well).

All four of those systems simulate the process of a character having sat down to decide how to spend his resources, having to do some trade-offs. But the two GURPS systems does it in much greater detail, and crucially they do it in much greater tied-into-the-world detail.

Personally, I really like that I can get actual answers, genuine answers, about whether or not a given spaceship or rocket can get from surface to orbit, here on Earth or on Mars or on Luna or any other planet or moon with known stats.

GURPS Vehicles gives me that but in an elaborate and roundabout way, one that is very detail-heavy.

GURPS Spaceships gives it to me in a much simpler way, meaning that with some practice working with the system, I should be able to crank out 5-8 "basic world" vehicles per hour, so that for instance I know how the dominant tech culture in my setting gets from surface to orbit, what vehicle types they use for that, and how costly they are to run (money isn't just about bying the vehicle, you buy the fuel too!) how they get from orbit to another far-away orbit, or move around inside an orbit, e.g. from space station to space station. What's long-distance passenger transport like, do they all hibernate or are roomy cabins fairly affordable?

The main downside of GURPS Spaceships is that there's no easy angle for characters to customize their spaceships with upgrades.

[whswhs]

Originally Posted by Ulzgoroth

As far as ship design, there hardly are any pages to reference. You read page 8 (or page 5) where it tells you there are 20 systems in a ship in three sets of six and two [core]s, go through the hull size bit on page 9 to choose an SM, and then there's one big list (p9-28) that you pick systems from to fill your 20 slots.

Yeah, that's what I thought, and it's exactly why I can't use it. I have no idea what's supposed to be core and what isn't, or where you put what system, or what systems it's essential to have, or what systems have to be proportioned to what other systems. I don't have a design sequence. "Go through this list and pick things out" isn't enough of a structure.

[ericthered]

Originally Posted by whswhs

Yeah, that's what I thought, and it's exactly why I can't use it. I have no idea what's supposed to be core and what isn't, or where you put what system, or what systems it's essential to have, or what systems have to be proportioned to what other systems. I don't have a design sequence. "Go through this list and pick things out" isn't enough of a structure.

That's easy enough to explain:

The essentials are three sets of armour (one for each section), a control room, and an engine. the engine will require fuel, power plants, or both -- but it will tell you how much you need in the description. The rest of the ship can be used for whatever -- cargo, habitats, factories, sensors, more engines, ect. Engines go in the back. Systems that can't be core will let you know. If something doesn't fit the original design, swap it.

[WingedKagouti]

Originally Posted by Warden

Do you sometimes labour under the number crunching that GURPS sometimes requires?

In actual gameplay? Absolutely not.

The math you'll usually find in gameplay is either roll the dice and add/subtract this number or take this number and find where it fits on that table.

There are a couple of tools available to help with the number crunching that can occur during character creation, so stuff like standing/running jump distance is automatically handled.

The vehicle and star system math is only for those who a) want "realistic" portrayal of the world and b) don't care about how much math they need for this. It's optional sections in optional books and generally only something a GM would ever need to bother with once per campaign.

[Fred Brackin]

Originally Posted by whswhs

Yeah, that's what I thought, and it's exactly why I can't use it. I have no idea what's supposed to be core and what isn't, or where you put what system, or what systems it's essential to have, or what systems have to be proportioned to what other systems. I don't have a design sequence. "Go through this list and pick things out" isn't enough of a structure.

The importance of "core" systems is that they can't be targeted in an undamaged ship. Putting a Control Room and a Power Plant in these slots is good but not mandatory. Very little is either mandatory or forbidden. specific cases are noted when one of these conditions does apply.

Systems that have to be proportional to other systems are mostly power plants. Some systems like weapons or FTL drives are noted as being "high energy". each one of those needs one "Power point". The number of PP that each module f power plant makes is in the item description. You don't even have to have enough PP to power everything at once. You just choose which systems to power at one time. For example, weapons and FTL drives are seldom needed at the same time.

For other systems the general rule is that more is more. more cargo modules lets you carry more cargo. More Fuel tanks give you more delta-v and so on.

[Ulzgoroth]

Originally Posted by whswhs

Yeah, that's what I thought, and it's exactly why I can't use it. I have no idea what's supposed to be core and what isn't, or where you put what system, or what systems it's essential to have, or what systems have to be proportioned to what other systems. I don't have a design sequence. "Go through this list and pick things out" isn't enough of a structure.

You are looking for more complexity than you will actually find. The system has very little interdependency...your picking stuff from a list is nearly as free as the picking stuff from a list stage of character creation.

What should be core: Location and Other Restrictions (p9) specifies that only systems with the [any] tag (as opposed to [hull], [rear], or [front]) can go in a core position. That's the only requirement in general, and will be easy to fulfill. You're additionally required to use one of them for part of a spinal battery (p28) if you decide to use one of those, as clearly specified in the spinal battery section. Core systems are somewhat shielded from attacks by the other systems, so you might want to put things you want to protect there, but that's not required.

Where you can't put what system: Location and Other Restrictions, p9, it's semi-clearly labeled on every system, and is almost never a problem. If you start designing a ship by picking 20 systems and then decide where to slot them in, you will almost always be able to make a legal design.

What systems are essential: technically none, but anything you'd call a ship needs a Control Room (p14). And you almost certainly want a Reaction Engine (p21-23) or Reactionless Engine (p24) so that your ship can move. Reaction Engines will require Fuel Tanks (p17) to be useful, and if you've used high energy systems (defined p9-10, marked with an ! inside the brackets with their location) you will need Power Plants (p20) to use them. A ship intended for long-term operations will need Habitat (p17) capacity for its crew.

What systems have to be proportioned to what other systems: The only thing that works even a little bit like that is power points for high energy systems. Each high energy system uses one point when active (unless specified otherwise) and each power plant produces a specified number of points depending on type.

[whswhs]

These various pieces of advice all seem somewhat helpful, but I don't think I could synthesize them into a step by step "Do A; now do B; now do C." It seems as if such a thing is implicit in what you say, but I'm not seeing it yet.