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Old 10-24-2016, 02:06 PM   #31
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Default Re: Gurps Vehicles / 4th. Edition

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The two best ways to know about SJ Games-related projects, from upcoming new releases to Kickstarter campaigns, are (1) being a regular on these forums, where we always promote such things, and (2) signing up for a Daily Illuminator email subscription, assuming you check your email regularly. If not, there are other options; click on any DI entry and then just look to the right.
There's also that new monthly email newsletter, which, I imagine, would mention things like Kickstarters but be less in your inbox than subscribing to the DI.
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Old 10-25-2016, 03:48 PM   #32
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Default Re: Gurps Vehicles / 4th. Edition

Yeah, my inbox is already overburdened, but I think I can handle a monthly newsletter. Thanks.
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Old 02-11-2017, 07:43 AM   #33
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Default Re: Gurps Vehicles / 4th. Edition

I am currently - again - experimenting with GURPS Spaceships. I tried to use it for a TL 5-6 Steampunk setting.

It works quite well for submarines, but for "normal" ships there are a ton of problems...

Even if I ignore the problem that most pre WW1 battleships where in the 15,000 to 20,000 range and just design them as 30,000 tons (with 10,000 there is no chance at all), a major conventional gun has a caliber of 28cm. Most post Dreadnought ships during WW 1 had at least 10 30cm+ guns - up to 8 38cm for Queen Elizabeth.

Also the system does not really support things like belt armor or special armored location or anything like superstructures.

What is also seriously missing is the damage type of guns... for that you need High Tech.

I love the hit location system. So basically what I do is taking the stats and tonnage distribution from real vehicles, round them to 5% and try to distibute them into the Spaceship system and let the Weapon Tables give me the damage for the guns, while determining range also from the real world stats of the weapons.
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Old 02-11-2017, 10:03 AM   #34
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Default Re: Gurps Vehicles / 4th. Edition

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I am currently - again - experimenting with GURPS Spaceships. I tried to use it for a TL 5-6 Steampunk setting.

It works quite well for submarines, but for "normal" ships there are a ton of problems...

Even if I ignore the problem that most pre WW1 battleships where in the 15,000 to 20,000 range and just design them as 30,000 tons (with 10,000 there is no chance at all), a major conventional gun has a caliber of 28cm. Most post Dreadnought ships during WW 1 had at least 10 30cm+ guns - up to 8 38cm for Queen Elizabeth.

Also the system does not really support things like belt armor or special armored location or anything like superstructures.

What is also seriously missing is the damage type of guns... for that you need High Tech.

I love the hit location system. So basically what I do is taking the stats and tonnage distribution from real vehicles, round them to 5% and try to distibute them into the Spaceship system and let the Weapon Tables give me the damage for the guns, while determining range also from the real world stats of the weapons.
That's one approach. What I tried to do with my approach on the previous page was to avoid too much mathematics and rely as much as possible on the progression on the SSR table that everything else uses.

So a 10,000 ton ship is SM10, a 15,000 ton ship is SM10 (Heavy), and 20,000 is SM11 (Light). I've found that this preserves the SM system, minimizes the calculations required, and still gives you a nice variety of tonnages in settings where the ships of interest are going to be all in roughly the same scale.

The rest you can do by buying oversized systems or simply hand-waving the caliber and assuming that those cannons were sized for a much higher TL.

I mostly ignore hit locations other than the three very broad facings. I assume that armor isn't ever going to be an even coat; designers will always try to optimize protection by vulnerability and probability of hit. So call the armor Hardened vs torpedoes if you like, or simply assume that the DR for a given size includes reasonable attempts to maximize actual in-practice protection. IIRC, there's an option in Pyramid to expand to six facings if you want it.

To me, the cool part of the design system in Spaceships is that it maximizes flexibility and playability, while still preserving a level of "realism". Most of the size hacks I've seen add back in all that mathematics which David Pulver worked so hard to strip out. To some extent that's unavoidable, but GURPS gives us a good system to precalculate scaling so I figure why not use that?
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Old 02-11-2017, 01:52 PM   #35
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Default Re: Gurps Vehicles / 4th. Edition

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That's one approach. What I tried to do with my approach on the previous page was to avoid too much mathematics and rely as much as possible on the progression on the SSR table that everything else uses.

So a 10,000 ton ship is SM10, a 15,000 ton ship is SM10 (Heavy), and 20,000 is SM11 (Light). I've found that this preserves the SM system, minimizes the calculations required, and still gives you a nice variety of tonnages in settings where the ships of interest are going to be all in roughly the same scale.
I did not write this to criticize your system. What I meant that if you have good reliable sources about real world vehicles written by experts on the field, you can just use them. In fact, that is less work.

My main source for real world ships is "Schlachtschiffe und Schlachtkreuzer. 1905-1970" by Siegfried Breyer. He seems to be quite accurate and my other books don't disagree with him on most parts. Especially newer research seems to proof that he was right far more often that he was wrong.

So if I know from pretty reliable and different sources that Dreadnought devoted 30% to armor, 11% to engines,17% to weapons, and so on and if I know how thick her armor was where and what weapons she carried, its basically less math to just round to full 5% and just use the Spaceship framework to represent my values.


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Originally Posted by wellspring View Post
To me, the cool part of the design system in Spaceships is that it maximizes flexibility and playability, while still preserving a level of "realism". Most of the size hacks I've seen add back in all that mathematics which David Pulver worked so hard to strip out. To some extent that's unavoidable, but GURPS gives us a good system to precalculate scaling so I figure why not use that?
I totally agree with you. But he did the calculations for spaceships and made a lot of assumptions which are pretty good for space ships, but do not work for water ships. Water ships do not need airtight bunk rooms and an oxygen supply for the crew. So the cabin equivalents are far too low for vehicles designed to work in an atmosphere.

Also it seems that his calibers where picked for guns with very long barrels and extreme muzzle velocities to make guns even remotely usable in space combat. The indirect fire artillery on ships which relied more on explosive power than kinetic penetration to pierce armor worked very different. (he assumes 1 mile per second muzzle velocity for conventional guns. TL6 to early TL7 naval guns had about half of this)

So while the system works great for spaceships, you have to tinker a lot to make it work with naval ships or - well - a typical main battle tank. That's why I think it is easier to just use the real data and plug them into the system, than to tweak the system until it agrees with your real data.
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Old 02-11-2017, 04:11 PM   #36
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Default Re: Gurps Vehicles / 4th. Edition

And that realism and playability are often competing goals for which different players and settings choose different lines.
Quite a few consider Solar power plants in Spaceships to produce 100 times the energy possible to compete at all with the other forms. Without the math done, those such assumptions get hidden and may cause problems that wouldn't exist if GMs knew ahead of time what was and was not realistic. Aside from the more overt ^ for egregious "this if obviously superscience" techs.
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Old 02-11-2017, 06:59 PM   #37
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Honestly, the main issue with using Spaceships for things that aren't, well, spaceships are the guns and missiles. Those are so optimized for space combat (and so different from what most people think of when it comes to missiles and bullets) they make little sense to use for relatively short range combat in the atmosphere. Honestly, probably the best way to build those weapons currently is to use 3e Vehicles and just cut Acc in half (you'll also need to use 3e's TL cutoffs, which are the same up to the end date of TL 4 but deviate thereafter; a decent workaround though is to read "late TL 5" as TL 6, and add 1 to TL thereafter). Ignore SS and the like, and don't bother with MinST (they're mounted weapons). For Rcl, 3e's Rcl was different, so you'll want to just assign that based on similar weapons that have already been statted up.


Beyond that, things like concentrated armor are fairly easy to handle - you figure out how much coverage the concentrated armor actually gives, and adjust appropriately. Say you've got 2 armor systems on the Front hull, but these are actually concentrated near the center of the ship. If it only covers, say, a third of the available surface area, that's 3x (6/2) the DR but only 2/6 coverage (on a random hit, roll 1d - on a 1 or 2, the armor protects, otherwise it doesn't).

If you don't already have them, Alternate Spaceships (Pyramid #3/34) and Spaceships 7 will go a long way toward helping you design vehicles that aren't spaceships. The former has things like internal combustion engines, underwater propellers, tracked and wheeled drivetrains, rules for minimal/no life support, and so forth. The latter has the rules for vehicles that lack automation, information on nautical lines and top decks, and so forth. Depending on how far back you want to go, other Pyramid articles may be of use. For example, Sailing the Open Skies (Pyramid #3/64), in addition to building magical airships, also has rules for more down-to-Earth designs - mundane oars, sails, and steam engines.
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Old 02-13-2017, 02:37 PM   #38
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Default Re: Gurps Vehicles / 4th. Edition

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Honestly, probably the best way to build those weapons currently is to use 3e Vehicles and just cut Acc in half...
You also basically have to take the square root of the higher damage values (above 10d6: damage dice = sqrt(damage dice - 10) + 10 or something like that).
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Old 02-13-2017, 02:44 PM   #39
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Default Re: Gurps Vehicles / 4th. Edition

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You also basically have to take the square root of the higher damage values (above 10d6: damage dice = sqrt(damage dice - 10) + 10 or something like that).
Most of my work with converting Vehicles weaponry to 4e has been at lower TL's, and I know that the values there work out perfectly fine for TL 4 cannon, most of which are well above 10d. I'll go ahead and pick out a random WWI cannon in HT and make it with Vehicles to see what I get; I'll let you know what I get.
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Old 02-13-2017, 03:54 PM   #40
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Default Re: Gurps Vehicles / 4th. Edition

So, the Schneider Mle 1897 turns out to be at a breakpoint where the Vehicles rules don't quite give it enough damage, although a higher-resolution version I came up with through observation of how things in Vehicles scale ends up giving it exactly the right damage with P=1. Weight, Range, and Acc are a bit off, so those might need some adjusting - Weight is 30% higher than it should be, 1/2D is about half what it should be (1000 instead of 2000), and Max is lower as well (5000 instead of 7000; note that 7000 was something of an artificial limit due to carriage design, and the weapon's "true" Max is something more like 13000). Acc is a bit high as well - the 3e 1/2D gives it a 3e Acc of 14, which halves to 7, when it should be 5.

Fixing these problems isn't too difficult. First, for my higher-resolution option, you calculate damage as 3*C*(L^0.5)*T*P, where C is caliber in inches (you can turn this to mm by turning the 3 into 0.12), L is length in calibers (the above weapon has a caliber of 3 inches and a length of 108 inches, so 36 calibers), T is the TL multiplier from the book, and P is Power (the book limits it to very low, low, and normal, but I allow for any value up to 1). Weight is instead calculated as 1.875*C*C*C*L*T*R*P, with C, L, T, and P as defined above (but note T changes depending on what it's used in - the T for damage and T for weight are different). R is the multiplier based on design from the book. Assuming that +30% is a constant issue, change 1.875 to 1.5, which will get you more where you need to be (for the above weapon, you end up with 1050 lb - 1000 if you round as Vehicles suggests - instead of 1008 lb). 1/2D is really more a function of bullet design and caliber than anything else, which is probably relatively constant for weapons at a given TL - in this case, use C*700, which will give you a 1/2D of 2100 (exactly what HT gives). Max is more complicated, but rarely matters - I'd just go with 5x 1/2D and be done with it. For Acc, you're best off just assigning it based on similar weapons.

When recreating historical weapons, your best bet is to assign P based on weight and let that dictate damage. For example, if I were working on making the Schneider Mle 1897 using the above equations, I could use historical data to find that it has a caliber of 3 inches, a length of 36 calibers, and a weight of 1008 lb (once you subtract the carriage). Plugging those in to the equation for weight would give me 1.5*27*36*T*R*P=1008, or P=1/(1.458*T*R). Noting this is a breachloader at TL 6, I'd get a P of 1.05, which I'd round down to 1, and use that to calculate damage.
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