[Spaceships] Perpetual Motion?

[Ulzgoroth]

Originally Posted by acrosome

Also, since the chemical refinery makes rocket fuel, is there a rule to divide production by 9 if you're only keeping the hydrogen? This seems reasonable- an oxygen molecule is mass 32, and two hydrogen molecules are mass 4, so the mass fraction is 4/36 = 1/9.

Seems correct, but I'm not aware of anything written to that effect.

Originally Posted by acrosome

Final question: Are there stats for what one power point is, somewhere?

Their official nonexistence is, I believe, quite intentional.

People have tried many times to puzzle them out, usually primarily from the beam weapon figures. I think there might be a revealing post from the author somewhere on the forum as well. (Possibly in connection with the beam weapon design Pyramid article instead of Spaceships, but you can work between the two...)

[weby]

Originally Posted by Ulzgoroth

Seems correct, but I'm not aware of anything written to that effect.

The example craft in staceships use the amount of HE3 in gas giant atmospheres as fraction of processed gas that is produced.

Originally Posted by Spaceships 6 page 21

About 130,000 tons of
raw atmosphere yields one ton of helium-3. As the Tempest’s
refineries process 20 tons an hour, this takes about 270 days

Their official nonexistence is, I believe, quite intentional.

People have tried many times to puzzle them out, usually primarily from the beam weapon figures. I think there might be a revealing post from the author somewhere on the forum as well. (Possibly in connection with the beam weapon design Pyramid article instead of Spaceships, but you can work between the two...)

The problems with power points is that the resulting number is silly high for chemical/solar planel compared to the later options and the difference in TL 6 to 12 is only *5 and between TL 7 and 12 is only *2.5.

Compare that to the other source without numbers: ultratech where the difference between TL 9 and TL 10 is *10 and the addition of ^ to the fusion plant multiples by *5 again and the TL 9-12 is *100(the same for TL 9-11^) Also there you need *50 the mass to produce the same energy with solar panel than TL 12 antimatter.

But yes, the only "real" numbers we have on power are the beam weapon power numbers in spaceships.

The power situation is one of the great annoyances I have with gurps tech supplements.

[Ulzgoroth]

Originally Posted by weby

The example craft in staceships use the amount of HE3 in gas giant atmospheres as fraction of processed gas that is produced.

...Does this have anything to do with the subject of how much hydrogen you get from electrolysis of water?

[weby]

Originally Posted by Ulzgoroth

...Does this have anything to do with the subject of how much hydrogen you get from electrolysis of water?

It would indicate that the output is relative to the mass fraction and the capacity as given for chemical refinery is the input mass, as you were replying to just keeping the hydrogen question.

[Flyndaran]

Originally Posted by weby

...
The problems with power points is that the resulting number is silly high for chemical/solar planel compared to the later options and the difference in TL 6 to 12 is only *5 and between TL 7 and 12 is only *2.5.
...

But most future techs aren't just about power density per ton of plant. There are many other factors making a technology desired.
Reliability, commonality/cost of fuel, radiation/toxic dangers, complexity, hassle of maintenance, etc.

[weby]

Originally Posted by Flyndaran

But most future techs aren't just about power density per ton of plant. There are many other factors making a technology desired.
Reliability, commonality/cost of fuel, radiation/toxic dangers, complexity, hassle of maintenance, etc.

It depends a lot on the setting/ideology/threat. For civilian mature technology, absolutely. For military in a full war situation a lot less.

As example quite many of the warships in the SS series have two reactors. Being able to reduce that to one or less would be a tremendous boost for many of them. In addition the higher TL ones with force screens could run with the improved DR always in combat.

Basically at minimum a ship with a reactionless drive has 6 modules: 3 armor, 1 control, 1 drive, 1 reactor, leaving 14 modules for other stuff. Thus a reduction in power density where you can reduce one module you get 7% more capacity, if you can reduce two you get almost 15% increase.

[acrosome]

Originally Posted by weby

The example craft in staceships use the amount of HE3 in gas giant atmospheres as fraction of processed gas that is produced.

Ah! Thanks, I'll take that as RAW, then.

Originally Posted by weby

But yes, the only "real" numbers we have on power are the beam weapon power numbers in spaceships.

The power situation is one of the great annoyances I have with gurps tech supplements.

Hmmm, yeah. I really just want to know what and how fast PCs can recharge other things if they try to do such, so I need some sort of estimate in kW. I guess that for almost all purposes I can just say "your average spaceship reactor produces a stupid amount of power" (for most values of stupid) but for the really small ones this might not be true.

Originally Posted by weby

Feasibility of anti-matter power plants comes really primarily down to containment, can you make them small and light enough to trap reasonable amounts of antimatter in small enough place to compete with other things.

Shielding is really a smaller thing as most envisioned technologies for such actually also work as at least partial shielding, reducing the need for physical shielding considerably or totally.

I'd propose that if you can make a fusion reactor, you can likely contain antimatter. The question IMO is the reliability of that containment. But since fusion power is TL9, then at TL10 it's probably pretty reliable.

[Ulzgoroth]

Originally Posted by acrosome

Hmmm, yeah. I really just want to know what and how fast PCs can recharge other things if they try to do such, so I need some sort of estimate in kW. I guess that for almost all purposes I can just say "your average spaceship reactor produces a stupid amount of power" (for most values of stupid) but for the really small ones this might not be true.

Nothing else in 4e uses power rated in kW either, does it?

Converting between Power Points and Power Cells/time is actually very doable by way of the beam weapon design article.

Originally Posted by acrosome

I'd propose that if you can make a fusion reactor, you can likely contain antimatter. The question IMO is the reliability of that containment. But since fusion power is TL9, then at TL10 it's probably pretty reliable.

Being able to contain antimatter isn't the issue. We can contain antimatter.

The issue is how efficiently you can contain antimatter. If your containment is several orders of magnitude heavier than the material contained, you're losing a lot off the theoretical density advantage of antimatter. (Though the relatively short endurance of AM reactors in Spaceships suggests that it's not extending that advantage anyway.)

[Flyndaran]

Originally Posted by acrosome

Ah...
I'd propose that if you can make a fusion reactor, you can likely contain antimatter. The question IMO is the reliability of that containment. But since fusion power is TL9, then at TL10 it's probably pretty reliable.

Not really. Fusion is kind of in the labs now, but we are nowhere near being able to make more than single atoms of antimatter with horrifically bad efficiency let alone know how to contain them for human scales of time. Getting those storages down to levels where the power densities approach gasoline let alone unshielded fission reactors would be massive tech improvements on their own.

Antimatter is nice for how simple it is to explain to us laymen. But I doubt it will ever be used for energy storage in our universe or reasonable hard science fiction setting.

[Varyon]

Originally Posted by acrosome

Final question: Are there stats for what one power point is, somewhere?

I have a document I haven't worked on in some time that set out to integrate Vehicles (3e) with Spaceships (4e). I opted to go with kW/ton (weight here being vessel mass, not system mass) rather than PP. Here's how the systems stack up.

Solar		TL7	TL8	TL9	TL10
PP		1	1	1	1
kW/ton		1	2	5	10

Fuel Cell	TL7	TL8	TL9	TL10
PP (endurance)	1 (3h)	1 (6h)	1 (12h)	1 (24h)
kW/ton (end)	5 (4h)	10 (4h)	20 (4h)	20 (8h)

Fission		TL8	TL9	TL10
PP (end)	1 (25y)	1 (50y)	1 (100y)
kW/ton (2y)	15	30	100
*Under my system, refueling the reactor is only 10% of the initial cost.
 Long-endurance reactors are also available, which have 1/3rd normal output
 but a 100 year endurance and cost 50% to refuel.

Fusion		TL9	TL10	TL11	TL12
PP (end)	2 (50)	2 (200)	2 (600)	2 (1200)
kW/ton (200y)	100	200	500	500

That's just a taste. Clearly, there's a significant inconsistency in PP->kW/ton, even if we were to adjust for endurance. For Solar Panels, this scales by TL, averaging around 1 PP = 5 kW/ton. For Fuel Cells, it also works out to around 1 PP = 5 kW/ton. For Fission, it's something around 1 PP = 20 kW/ton for TL8 and 9, and 1 PP = 30 kW/ton for TL10. For Fusion, there's a different scaling with TL for the systems, but it works out to around 1 PP = 100 kW/ton.

From weapons, 1 PP for SM+5 can power a 10 MJ weapon indefinitely. As this weapon only fires every 20 seconds, that's 500 kW. An SM+5 vessel weighs 30 tons, so you're looking at around 1 PP = 15 kW/ton. Of course, that's output, where you're going to see some efficiency drops. The minimum here is actually 1 PP = 30 kW/ton, assuming the Improved versions of beam weapons have close to 100% efficiency.

From a refinery, 1 PP for SM+5 can process 0.5 tons of water into rocket fuel every hour. Hydrogen has a heat of combustion of 141.8 MJ/kg (HHV); as there are around 907.185 kg/ton, that means we're dealing with around 600 kW/ton. Again, this is output, so there should be some efficiency losses along the way. This also helps demonstrate why the rate at which the refinery produces rocket fuel is probably broken - by the above, you'd need around 3 fusion reactors to run that thing! Using the SS7 fix, with hours replaced by days, results in around 25 kW/ton, which is pretty close to the output of Improved beam weapons, above.