Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 10-28-2015, 03:52 PM   #21
Flyndaran
Untagged
 
Join Date: Oct 2004
Location: Forest Grove, Beaverton, Oregon
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by weby View Post
...
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.
__________________
Beware, poor communication skills. No offense intended. If offended, it just means that I failed my writing skill check.
Flyndaran is offline   Reply With Quote
Old 10-28-2015, 04:40 PM   #22
weby
 
weby's Avatar
 
Join Date: Oct 2008
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by Flyndaran View Post
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.
__________________
--
GURPS spaceship unofficial errata and thoughts: https://gsuc.roto.nu/
weby is offline   Reply With Quote
Old 10-28-2015, 05:34 PM   #23
Flyndaran
Untagged
 
Join Date: Oct 2004
Location: Forest Grove, Beaverton, Oregon
Default Re: [Spaceships] Perpetual Motion?

Technically, unless travelling at reasonable percentage of C, or through atomsphere, spaceships don't need any armor.
Control modules can be smaller than a full 5% if you don't mind it steering like a drunk whale.

Power Plants are only necessary if you have energy hungry modules like energy weapons, shields, or most reactionless drives.

I understand why energy density is important for militaries. But the differences between most fusion and fission designs isn't that, except for types that can do away with shielding.

Antimatter plants seem more like light superscience to me, especially since they don't seem to include shielding.
__________________
Beware, poor communication skills. No offense intended. If offended, it just means that I failed my writing skill check.
Flyndaran is offline   Reply With Quote
Old 10-28-2015, 08:23 PM   #24
weby
 
weby's Avatar
 
Join Date: Oct 2008
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by Flyndaran View Post
Technically, unless travelling at reasonable percentage of C, or through atomsphere, spaceships don't need any armor.
Control modules can be smaller than a full 5% if you don't mind it steering like a drunk whale.
I was talking about military ships and most military ships will want all around armor and reasonable control.

Quote:
Power Plants are only necessary if you have energy hungry modules like energy weapons, shields, or most reactionless drives.
And military ships without such tend to be pretty useless unless unless built for missile/conventional gun only, but then their point defense suffers.

Quote:
I understand why energy density is important for militaries.
And things like racing or "sport vehicle". A sports car engine can produce 10 times the power/weight of an economy car engine today. That difference is larger than the projected difference between TL 6 and TL 12 in space ships total.

Quote:
But the differences between most fusion and fission designs isn't that, except for types that can do away with shielding.
Indeed likely so. But that is not the point, the point is that military need would likely drive any sort of technology to be as light as possible for inclusion on military starships as long as those ships have to obey the laws of physics even remotely (that is acceleration is dependent on thrust/mass)

Military need in this context being actual conflict instead of long peacetime space navy that might indeed see serviceability as goal #1.

Quote:
Antimatter plants seem more like light superscience to me, especially since they don't seem to include shielding.
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.
__________________
--
GURPS spaceship unofficial errata and thoughts: https://gsuc.roto.nu/
weby is offline   Reply With Quote
Old 10-29-2015, 08:49 AM   #25
acrosome
 
acrosome's Avatar
 
Join Date: Aug 2010
Location: The Land of Enchantment
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by weby View Post
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.

Quote:
Originally Posted by weby View Post
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.

Quote:
Originally Posted by weby View Post
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.
acrosome is offline   Reply With Quote
Old 10-29-2015, 08:56 AM   #26
Ulzgoroth
 
Join Date: Jul 2008
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by acrosome View Post
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.
Quote:
Originally Posted by acrosome View Post
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.)
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 10-29-2015, 09:12 AM   #27
Varyon
 
Join Date: Jun 2013
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by acrosome View Post
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.

Code:
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.

Last edited by Varyon; 10-29-2015 at 09:15 AM.
Varyon is online now   Reply With Quote
Old 10-29-2015, 03:43 PM   #28
Flyndaran
Untagged
 
Join Date: Oct 2004
Location: Forest Grove, Beaverton, Oregon
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by acrosome View Post
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.
__________________
Beware, poor communication skills. No offense intended. If offended, it just means that I failed my writing skill check.
Flyndaran is offline   Reply With Quote
Old 10-29-2015, 04:02 PM   #29
Fred Brackin
 
Join Date: Aug 2007
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by Flyndaran View Post
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. .
It's a little better than that. SOTA antimatter storage is a "Penning
Trap" which I believe holds about 100,000 anti-protons.
__________________
Fred Brackin
Fred Brackin is offline   Reply With Quote
Old 10-29-2015, 05:05 PM   #30
Flyndaran
Untagged
 
Join Date: Oct 2004
Location: Forest Grove, Beaverton, Oregon
Default Re: [Spaceships] Perpetual Motion?

Quote:
Originally Posted by Ulzgoroth View Post
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.

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.)
Infinite Worlds has a portable fuel cell with listed performance stats. It's the only example I can think of, and for some reason a few people voiced displeasure with it.

The issue with Power Points is that none of the outputs would agree with each other for previously stated reasons.
They're so specialized for adventure and play balance amongst themselves that they simply won't work with real numbers ascribed. At least not without heavy adjustment.

Of course, I'm fine with such adjustment. Some technologies should be orders of magnitude better than others. Some, like mass drivers and solar arrays, really do suck compared to every other usable form in the same category. They're niche techs that work for very specific settings.
__________________
Beware, poor communication skills. No offense intended. If offended, it just means that I failed my writing skill check.
Flyndaran is offline   Reply With Quote
Reply

Tags
spaceships

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 11:16 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.