[Spaceships] 3e-Style Design System

the-red-scare · 03-26-2021, 03:31 PM

This is a pretty obvious idea, and I'm sure someone somewhere has done a version of it before, but I don't think it's been posted here.

Basic premise: Take the general design sequence from Space 3e, Transhuman Space, and Traveller, but make it mass-based like Spaceships, avoiding excessive calculations and design-check loops regarding things like thrust and delta-V. Why bother? To have more fiddly bits to customize than Spaceships offers and to have more fine-grained control over vessel size, etc. while retaining most of that Spaceships speed and simplicity.

Here we go.

0. One space is 5 tons. You can pretty much just use SM +6 systems from Spaceships as is, rejigger systems from the other books, or build your own from Vehicles or real life equipment. I'll be doing a little of all three, particularly for things like control systems, sensors, and weapons. There's no reason not to use larger systems from Spaceships if they fit in your hull. You can optionally also assign a volume to each system, for more accurate dDR calculation later. I don't bother.

1. Choose a hull size in spaces. Multiply by 5 to note the Lwt., which will not change at any point. Also note 5% of Lwt. rounded up to the nearest 5 tons - this will be our reference mass for things like drives and fuel tanks.

2. Start adding systems. Most of them can go in without concern, with a couple notes:

2a. Drives should be added in increments of the reference mass calculated above, to preserve Accel and avoid calculating tons of thrust and so on. For example, if the ship is 825 tons, the refence mass is 45 tons, so each "engine" is 9 spaces and has the performance of a Spaceships engine.

2b. Fuel tanks should also be added in increments of the reference mass, to allow the use of the delta-V table in Spaceships rather than doing the math of the rocket equation every time you add or subtract a system.

2c. By default, it's pretty easy to figure the dDR per armor system in a generic mass-to-area-assumption kind of way*. If you're tracking volume, armor systems are just placeholders until you get the final volume, which will lead to the final surface area, which will get you to dDR.

2d. If you want to make new systems for structure, have frame strength options, etc., it's not that hard to calculate but does detract from the ease of use. Otherwise assume the frame is subsumed in the systems themselves, and if it is relevant subtract 0.5 tons or so from available mass when designing your own systems to account for it.

3. Finalize the design and statistics per Spaceships, optionally using any particular rules or options from any other books that seem relevant.

4. Use the combat system of your choice. There are two ways to handle damage, since we don't have that convenient stat block to roll on. The easy way is to use a Major Damage table like all of the other books. The more complex way is to divide up all systems into 20 hull sections of 5% of Lwt. (or volume if you're using it). Call two of these "core sections" and give numbers to the rest, then use Spaceships rules. You then have to determine how to allocate damage to various bits within a section and... I think I'm just sticking with a Major Damage table.

---

* For a given Lwt., a vessel's notional length is the cube root of Lwt. * 15 ft. Its surface area is length^2 / 1,000 ksf if streamlined, or length^2 / 1,500 if unstreamlined. The dDR is SM +6 dDR from Spaceships multiplied by the number of armor systems installed, then divided by 2 * surface area. Round down the results. You can divide the total area by 3 and allocate systems if you want Spaceships-style front/center/rear hulls, or divide it any way you like to assign facings.

Example: Let's say our 825 ton (165 space) vessel has 42 spaces of armor. Its notional length is 140 ft. Its unstreamlined surface area is 13 ksf. We use light alloy armor with SM +6 dDR 3, so the ship's dDR is (3*42)/(2*13) or 4.8, which we round down to dDR 4.

Do I like having this calculation in the system? Not really. But I do prefer it to the performance calculations a volume-based system requires. Area could also be pre-calculated for a list of hull sizes as Space 3e and Traveller did.

dataweaver · 03-27-2021, 06:24 AM

My preferred approach is to just take the Spaceships design system and increase the resolution. I've posted elsewhere a set of revised tables that, instead of jumping straight from 100 tons to 300 tons to 1000 tons, takes you through increments of 100, 120, 150, 200, 250, 300, 400, 500, 600, and 800 tons before getting to 1000 tons. It's something I devised for mecha, as I wanted something like Battletech's 10-ton increments design system: on the “mecha and small craft” end of the scale, it goes 10, 12, 15, 20, 25, 30, 40, 50, 60, 80, 100.

If you'd like, I'll dig that up and repost it here; it's ultimately a lot less work than trying to turn Spaceships into a Space 3e style design sequence.

sparcipx · 03-27-2021, 06:38 AM

Quote:

Originally Posted by dataweaver

It's something I devised for mecha, as I wanted something like Battletech's 10-ton increments design system: on the “mecha and small craft” end of the scale, it goes 10, 12, 15, 20, 25, 30, 40, 50, 60, 80, 100.

If you'd like, I'll dig that up and repost it here; it's ultimately a lot less work than trying to turn Spaceships into a Space 3e style design sequence.

I'd certainly be interested in this. I've just started toying with mecha design (Spaceships 4 and a couple of Pyramid articles) and this sounds like it would be right up my alley.

dataweaver · 03-27-2021, 06:47 AM

http://forums.sjgames.com/showpost.p...4&postcount=55
http://forums.sjgames.com/showpost.p...7&postcount=59
http://forums.sjgames.com/showpost.p...4&postcount=60
http://forums.sjgames.com/showpost.p...9&postcount=57

sparcipx · 03-27-2021, 07:09 AM

Quote:

Originally Posted by dataweaver

http://forums.sjgames.com/showpost.p...4&postcount=55
http://forums.sjgames.com/showpost.p...7&postcount=59
http://forums.sjgames.com/showpost.p...4&postcount=60
http://forums.sjgames.com/showpost.p...9&postcount=57

Thanks, seems pretty straightforward.

dataweaver · 03-27-2021, 07:12 AM

You're welcome. Let me know if anything needs clarification, or if there are any other issues that crop up when you put it into use.

the-red-scare · 03-27-2021, 08:35 AM

Oh, I’ve been down that road, too. It’s an easier approach, but not what I’m going for.

I think the key difference I’m after is having systems of radically different sizes mixed together — say a 60,000 ton civilian cargo carrier that only needs a 1-ton sensor and a 10-ton bridge. You could do it with Spaceships as is and radical Smaller Systems rules, but it would get silly. With the old design system, you just put what you need and don’t have every other thing scaling up and down with the ship as a whole.

RyanW · 03-27-2021, 10:01 AM

Quote:

Originally Posted by the-red-scare

Oh, I’ve been down that road, too. It’s an easier approach, but not what I’m going for.

I think the key difference I’m after is having systems of radically different sizes mixed together — say a 60,000 ton civilian cargo carrier that only needs a 1-ton sensor and a 10-ton bridge. You could do it with Spaceships as is and radical Smaller Systems rules, but it would get silly. With the old design system, you just put what you need and don’t have every other thing scaling up and down with the ship as a whole.

Do note that the Control Room module is assumed to include the control thrusters and such, the actual room where the command crew sits can be a relatively minor part (or absent entirely) at the level of abstraction used in Spaceships. A ship that is less than 0.02% Control Room should basically have no ability to maneuver.

dataweaver · 03-27-2021, 10:06 AM

That's trivial. Just read the ship math as a maximum allowable mass, and assign each of the ship systems in Mass based on their size: 1.5 tons for SM+5, 5 tons for SM+6, 15 tons for SM+7, 50 tons for SM+8, 150 tons for SM+9, 500 tons for SM+10, and so on. 30% of your total mass can go in the front, 30% can go in the middle, 30% can go in the rear, and 5% can fit in each of the cores.

This avoids having to turn everything into continuous progressions; though if you want to go that route, this still helps in determining when the breakpoints kick in, such as when sensors switch from (TL-6) to (TL-5).

thrash · 03-27-2021, 10:13 AM

Quote:

Originally Posted by dataweaver

That's trivial. Just read the ship math as a maximum allowable mass, and assign each of the ship systems in Mass based on their size: 1.5 tons for SM+5, 5 tons for SM+6, 15 tons for SM+7, 50 tons for SM+8, 150 tons for SM+9, 500 tons for SM+10, and so on. 30% of your total mass can go in the front, 30% can go in the middle, 30% can go in the rear, and 5% can fit in each of the cores.

Ah, thank you. I was about to ask how you recommended handling systems that are quantized rather than proportional, like cabins.

03-26-2021, 03:31 PM	#1
the-red-scare Join Date: Sep 2014	[Spaceships] 3e-Style Design System This is a pretty obvious idea, and I'm sure someone somewhere has done a version of it before, but I don't think it's been posted here. Basic premise: Take the general design sequence from *Space* 3e, *Transhuman Space, and Traveller, but make it mass-based like Spaceships, avoiding excessive calculations and design-check loops regarding things like thrust and delta-V. Why bother? To have more fiddly bits to customize than Spaceships* offers and to have more fine-grained control over vessel size, etc. while retaining most of that *Spaceships* speed and simplicity. Here we go. 0. One space is 5 tons. You can pretty much just use SM +6 systems from Spaceships as is, rejigger systems from the other books, or build your own from *Vehicles* or real life equipment. I'll be doing a little of all three, particularly for things like control systems, sensors, and weapons. There's no reason not to use larger systems from *Spaceships* if they fit in your hull. You can optionally also assign a volume to each system, for more accurate dDR calculation later. I don't bother. 1. Choose a hull size in spaces. Multiply by 5 to note the Lwt., which will not change at any point. Also note 5% of Lwt. rounded up to the nearest 5 tons - this will be our reference mass for things like drives and fuel tanks. 2. Start adding systems. Most of them can go in without concern, with a couple notes: 2a. Drives should be added in increments of the reference mass calculated above, to preserve Accel and avoid calculating tons of thrust and so on. For example, if the ship is 825 tons, the refence mass is 45 tons, so each "engine" is 9 spaces and has the performance of a *Spaceships* engine. 2b. Fuel tanks should also be added in increments of the reference mass, to allow the use of the delta-V table in *Spaceships* rather than doing the math of the rocket equation every time you add or subtract a system. 2c. By default, it's pretty easy to figure the dDR per armor system in a generic mass-to-area-assumption kind of way. If you're tracking volume, armor systems are just placeholders until you get the final volume, which will lead to the final surface area, which will get you to dDR. 2d. If you want to make new systems for structure, have frame strength options, etc., it's not that hard to calculate but does detract from the ease of use. Otherwise assume the frame is subsumed in the systems themselves, and if it is relevant subtract 0.5 tons or so from available mass when designing your own systems to account for it. 3. Finalize the design and statistics per Spaceships, optionally using any particular rules or options from any other books that seem relevant. 4. Use the combat system of your choice. There are two ways to handle damage, since we don't have that convenient stat block to roll on. The easy way is to use a Major Damage table like all of the other books. The more complex way is to divide up all systems into 20 hull sections of 5% of Lwt. (or volume if you're using it). Call two of these "core sections" and give numbers to the rest, then use Spaceships* rules. You then have to determine how to allocate damage to various bits within a section and... I think I'm just sticking with a Major Damage table. --- * For a given Lwt., a vessel's notional length is the cube root of Lwt. * 15 ft. Its surface area is length^2 / 1,000 ksf if streamlined, or length^2 / 1,500 if unstreamlined. The dDR is SM +6 dDR from *Spaceships* multiplied by the number of armor systems installed, then divided by 2 * surface area. Round down the results. You can divide the total area by 3 and allocate systems if you want *Spaceships-style front/center/rear hulls, or divide it any way you like to assign facings. Example: Let's say our 825 ton (165 space) vessel has 42 spaces of armor. Its notional length is 140 ft. Its unstreamlined surface area is 13 ksf. We use light alloy armor with SM +6 dDR 3, so the ship's dDR is (342)/(213) or 4.8, which we round down to dDR 4. Do I like having this calculation in the system? Not really. But I do prefer it to the performance calculations a volume-based system requires. Area could also be pre-calculated for a list of hull sizes as Space* 3e and *Traveller* did.

03-27-2021, 06:24 AM	#2
dataweaver Join Date: Aug 2004	Re: [Spaceships] 3e-Style Design System My preferred approach is to just take the Spaceships design system and increase the resolution. I've posted elsewhere a set of revised tables that, instead of jumping straight from 100 tons to 300 tons to 1000 tons, takes you through increments of 100, 120, 150, 200, 250, 300, 400, 500, 600, and 800 tons before getting to 1000 tons. It's something I devised for mecha, as I wanted something like Battletech's 10-ton increments design system: on the “mecha and small craft” end of the scale, it goes 10, 12, 15, 20, 25, 30, 40, 50, 60, 80, 100. If you'd like, I'll dig that up and repost it here; it's ultimately a lot less work than trying to turn Spaceships into a Space 3e style design sequence. __________________ Point balance is a myth.[1][2][3][4]

03-27-2021, 06:47 AM	#4
dataweaver Join Date: Aug 2004	Re: [Spaceships] 3e-Style Design System http://forums.sjgames.com/showpost.p...4&postcount=55 http://forums.sjgames.com/showpost.p...7&postcount=59 http://forums.sjgames.com/showpost.p...4&postcount=60 http://forums.sjgames.com/showpost.p...9&postcount=57 __________________ Point balance is a myth.[1][2][3][4]

03-27-2021, 07:12 AM	#6
dataweaver Join Date: Aug 2004	Re: [Spaceships] 3e-Style Design System You're welcome. Let me know if anything needs clarification, or if there are any other issues that crop up when you put it into use. __________________ Point balance is a myth.[1][2][3][4]

03-27-2021, 08:35 AM	#7
the-red-scare Join Date: Sep 2014	Re: [Spaceships] 3e-Style Design System Oh, I’ve been down that road, too. It’s an easier approach, but not what I’m going for. I think the key difference I’m after is having systems of radically different sizes mixed together — say a 60,000 ton civilian cargo carrier that only needs a 1-ton sensor and a 10-ton bridge. You could do it with Spaceships as is and radical Smaller Systems rules, but it would get silly. With the old design system, you just put what you need and don’t have every other thing scaling up and down with the ship as a whole.

03-27-2021, 10:06 AM	#9
dataweaver Join Date: Aug 2004	Re: [Spaceships] 3e-Style Design System That's trivial. Just read the ship math as a maximum allowable mass, and assign each of the ship systems in Mass based on their size: 1.5 tons for SM+5, 5 tons for SM+6, 15 tons for SM+7, 50 tons for SM+8, 150 tons for SM+9, 500 tons for SM+10, and so on. 30% of your total mass can go in the front, 30% can go in the middle, 30% can go in the rear, and 5% can fit in each of the cores. This avoids having to turn everything into continuous progressions; though if you want to go that route, this still helps in determining when the breakpoints kick in, such as when sensors switch from (TL-6) to (TL-5). __________________ Point balance is a myth.[1][2][3][4]