GURPS Spaceships in use: Traveller Ship Templates

[thtraveller]

I have created a variety of standard Traveller ship templates with G:Spaceships adapted for Traveller to see what tweaks need to be made and options used. At present these are just outline templates to test the theory (they are not costed or statted up).

Basic tweaks made and options used:
1) Up to half of Jump Fuel tanks can occupy Armor spaces - this is to get around the Mass issue for low density Hydrogen fuel - with the G:Spaceships base system - while still keeping to the spirit of Traveller 10% fuel per J number.

2) J-drive are fixed size Stardrives (5% of hull by Mass) but increasing cost and power per J-number

3) Uses Super Fusion reactors to get close to Traveller ship capabilities. These are changed to be available from TL10. These can be used downrated on commercial ships to save money.

Do the design suggestions make sense and fit Traveller?


First template: Jump-3 Warship with Spinal Mount

Front Hull
1 Armor+Jump Fuel
2 Jump Fuel
3 Spinal Battery (1pp)
4 Crew Cabins
5 Crew Cabins, Sickbays, Workshops
6 Bridge

Central Hull
1 Armor+Jump Fuel
2 Jump Fuel
3 Jump Fuel
4 Super Fusion (-4 PP)
5 Tertiary Battery (1pp - 30 point defence weapons)
6 Jump-drive (J3) (3pp)
Core Spinal Battery (1pp)

Rear Hull
1 Armor+Jump Fuel
2 Reactionless Thruster (1pp)
3 Reactionless Thruster (1pp)
4 Reactionless Thruster (1pp)
5 Reactionless Thruster (1pp)
6 Spinal Battery (1pp)
Core Super Fusion (-4 PP)

Basic performance: TL10 2G, TL11+ 4G

Ship has 3pp shortfall - so it cannot do a running jump while firing all its weapons

Ideally I would like to get a decent tactical sensor suite in there too. Maybe it wont be quite so tight when I stat it properly. Maybe.

Does that look about right?

[thtraveller]

Second Template: Jump 6 Express Courier

Front Hull
1 Armor+Jump Fuel
2 Jump Fuel
3 Jump Fuel
4 Cargo
5 Cargo
6 Crew Cabins/Habitat Area
Core Bridge

Central Hull
1 Armor+Jump Fuel
2 Jump Fuel
3 Jump Fuel
4 Jump Fuel
5 Jump Fuel
6 Jump Fuel
Core Super Fusion (-4pp)

Rear Hull
1 Armor+Jump Fuel
2 Jump Fuel
3 Jump Fuel
4 Super Fusion (-4pp)
5 Jump Drive (J6 6pp)
6 Reactionless Thruster (1pp)

Base Performance TL10 0.5, TL11+ 1G

[Peter Knutsen]

Originally Posted by thtraveller

I have created a variety of standard Traveller ship templates with G:Spaceships adapted for Traveller to see what tweaks need to be made and options used. At present these are just outline templates to test the theory (they are not costed or statted up).

Basic tweaks made and options used:
1) Up to half of Jump Fuel tanks can occupy Armor spaces - this is to get around the Mass issue for low density Hydrogen fuel - with the G:Spaceships base system - while still keeping to the spirit of Traveller 10% fuel per J number.

What do you mean by this?

Are you saying tha you are "splitting" one of the 5%-mass-modules, so that a part of the mass is devoted to armour, and the other part to hydrogen jump fuel?

If yes, what procedure do you use?

The one I'd use would be to simply apply divisors to the dDR value of the armour, and its monetary cost, and of course apply a divisor to the amount of fuel.

For instance, if for a given ship size and TL the dDR value is 20 and the monetary cost is 20M$, then if I decide to split the module 4 ways, and devote 1/4 to armour and 3/4 to fuel, then the dDR value becomes 5 and the monetary cost of the armour becomes 5M$. The remaining 3/4 of the mass is fuel tankage.

(If you do this, you may want to consistently employ a 3-way split. Doing that simplifies the combat rules, and also means that if you do one such split module per hull section, it counts as 2 modules of fuel total, which is neat and simple.)

Originally Posted by thtraveller

2) J-drive are fixed size Stardrives (5% of hull by Mass) but increasing cost and power per J-number

That is probably the best solution.

Originally Posted by thtraveller

3) Uses Super Fusion reactors to get close to Traveller ship capabilities. These are changed to be available from TL10. These can be used downrated on commercial ships to save money.

Do the design suggestions make sense and fit Traveller?

The only TU version I'm at all familiar with is the GURPS one, but your suggestions sound sensible. Likely to result in something not too dissimilar from the universe that emerges from the GURPS Traveller rules.

Originally Posted by thtraveller

First template: Jump-3 Warship with Spinal Mount

Front Hull
1 Armor+Jump Fuel
2 Jump Fuel
3 Spinal Battery (1pp)
4 Crew Cabins
5 Crew Cabins, Sickbays, Workshops
6 Bridge

Central Hull
1 Armor+Jump Fuel
2 Jump Fuel
3 Jump Fuel
4 Super Fusion (-4 PP)
5 Tertiary Battery (1pp - 30 point defence weapons)
6 Jump-drive (J3) (3pp)
Core Spinal Battery (1pp)

Rear Hull
1 Armor+Jump Fuel
2 Reactionless Thruster (1pp)
3 Reactionless Thruster (1pp)
4 Reactionless Thruster (1pp)
5 Reactionless Thruster (1pp)
6 Spinal Battery (1pp)
Core Super Fusion (-4 PP)

No ECM, no stealth?

All the Imperial Navy ships in GURPS Traveller Starships had maxed out stealth. Since this does not require giving up any module slots, it's a no-brainer for any ship intended for combat (sadly).

ECM costs module slots, so that's not such an obvious choice. It also makes sense to not devote mass to ECM if you're making a ship optimized for offence.

Originally Posted by thtraveller

Basic performance: TL10 2G, TL11+ 4G

Ship has 3pp shortfall - so it cannot do a running jump while firing all its weapons

Ideally I would like to get a decent tactical sensor suite in there too. Maybe it wont be quite so tight when I stat it properly. Maybe.

Does that look about right?

What is the dDR of the ship? And the Jump value, and the number of jumps that it can actually perform? And is it streamlined? It appears to have no contragravity.

Also, it has no hangar for auxillary craft. This means that (unless it is streamlined) it will have to rely on other ships for wilderness refuelling.

[thtraveller]

Originally Posted by Peter Knutsen

Are you saying tha you are "splitting" one of the 5%-mass-modules, so that a part of the mass is devoted to armour, and the other part to hydrogen jump fuel?

I am just borrowing the Armor module's volume for the moment - and putting a full unit of fuel in it. Once I get some feedback and work out what are the limits of the system I might do something more complex like half a unit of fuel in an armor module or your suggestion of two fuel modules split over 3 armor units, but it's probably below the resolution of the system. The armor (and the hidden frame) volume is probably quite tiny.

No ECM, no stealth?

I haven't statted them up, and added options, I am just seeing if the basic outline works at the moment.

Streamlined, Stealth & Artificial Gravity are obvious candidates that just add cost.

Also, it has no hangar for auxillary craft. This means that (unless it is streamlined) it will have to rely on other ships for wilderness refuelling.

It will probably be SL as getting a hangar in would further degrade its combat capability.

[Peter Knutsen]

Originally Posted by thtraveller

I am just borrowing the Armor module's volume for the moment - and putting a full unit of fuel in it. Once I get some feedback and work out what are the limits of the system I might do something more complex like half a unit of fuel in an armor module or your suggestion of two fuel modules split over 3 armor units, but it's probably below the resolution of the system. The armor (and the hidden frame) volume is probably quite tiny.

You're overlooking the fact that GURPs Spaceships is based on mass. Entirely on mass. Volume is regarded as completely irrelevant.

This means that each module represents 5% of the ship's mass. Thus the standard procedure is to devote 15% of the ship's mass to armour, if you want all 3 sections to be armoured, and 15% is fine for a military ship such as a destroyer or frigate (for a ship-of-the-line, 30% is probably ¨more suitable), but for civilian ships (including many IISS ships), 15% is too much, yet the unarmoured option (which gives you dDR 0.2 or 0.3 for free) is too little.

[thtraveller]

Originally Posted by Peter Knutsen

You're overlooking the fact that GURPs Spaceships is based on mass. Entirely on mass. Volume is regarded as completely irrelevant.

It is the Traveller Jump number * 10% fuel by volume that is driving the sharing and trying to make use of the mass basis of starships. Hydrogen fuel tanks are much lighter than the mass allocated to them if they were all installed as 2 fuel tank modules per jump number - as Hydrogen has such a low density. So allocating one real module and then one "virtual" module in the armor space evens out the mass - yet still retains the feel of Traveller. I hope.

[Peter Knutsen]

Originally Posted by thtraveller

It is the Traveller Jump number * 10% fuel by volume that is driving the sharing and trying to make use of the mass basis of starships. Hydrogen fuel tanks are much lighter than the mass allocated to them if they were all installed as 2 fuel tank modules per jump number - as Hydrogen has such a low density. So allocating one real module and then one "virtual" module in the armor space evens out the mass - yet still retains the feel of Traveller. I hope.

You cannot "allocate" anything in an armour module. A module is not an amount of volume, in GURPS Spaceships.

[Rupert]

Originally Posted by thtraveller

It is the Traveller Jump number * 10% fuel by volume that is driving the sharing and trying to make use of the mass basis of starships. Hydrogen fuel tanks are much lighter than the mass allocated to them if they were all installed as 2 fuel tank modules per jump number - as Hydrogen has such a low density. So allocating one real module and then one "virtual" module in the armor space evens out the mass - yet still retains the feel of Traveller. I hope.

One thing to consider is that the exact details vary from Traveller rules set to Traveller rules set. In High Guard armour took up significant volume, so if you want a HG sort of feel fuel should not share with armour. OTOH, if you want a GT sort of feel what you're doing makes sense because armour didn't take up volume.

Another thing to consider is that in HG a jump drive could be powered over the course of two turns (and in TNE/FF&S required no external power at all), so it's quite reasonable for a J-6 courier to have only one super-fusion module for 4PP (enough to charge the j-drive and manoeuvre a little).

[thtraveller]

Originally Posted by Rupert

One thing to consider is that the exact details vary from Traveller rules set to Traveller rules set. In High Guard armour took up significant volume, so if you want a HG sort of feel fuel should not share with armour. OTOH, if you want a GT sort of feel what you're doing makes sense because armour didn't take up volume.

I think Armor (and frame) occupy a little space, but not 15% of the ship, especially as armor is quote low DR by some Traveller standards, though it does provide some needed access space too.

I am only doing it because I think it is the only way to get everything in and maintain the Traveller feel.

I think we have the situation that a 10% of ship's volume Hydrogen fuel tank is probably no more than 5% of the ship's mass, whereas as an armor module is likely only around 1% of the ship's volume. So the trade-off to maintain Traveller feel seems logical as long as at least one armor module remains untouched for the access space it contains.

Another thing to consider is that in HG a jump drive could be powered over the course of two turns (and in TNE/FF&S required no external power at all), so it's quite reasonable for a J-6 courier to have only one super-fusion module for 4PP (enough to charge the j-drive and manoeuvre a little).

Hmm, that's interesting, I thought most versions of Traveller required the jump-drive to be fully powered throughout jump? I will see how I get on and how critical this is.