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Old 01-22-2018, 09:38 PM   #51
YankeeGamer
 
Join Date: Dec 2017
Default Re: Accumulators: A concept for GURPS Spaceships

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Originally Posted by Johnny1A.2 View Post
There are issues with superconducting loops, too, when we're talking about Smithian energy storage densities. Our current physics might not allow for any means of duplicating those accumulators, at least the ones in use by Kimball Kinnison's time.

Actually, given that the great powers all have access to total-conversion power plants by KK's time, the only real reason for them to use accumulators at all would be speed of delivery, and maybe emergency backup. Otherwise, you could store your energy in a very safe stable high-density form, i.e. matter. If you've got total conversion tech, you can store energy as something like blocks of lead or other compact material, and not have to worry about accidental discharges or anything else until you need it. Furthermore, your storage density is E=mc^2, so a gram of whatever equals 25 gigawatt-hours. That's pretty good.
That is more than "Pretty good." But Kinnison's ships still had accumulators beyond just power plants. IIRC, they even had them when total conversion was only used as an exciter for "Cosmic Power Screens," a starkly amazing power supply.

Last edited by YankeeGamer; 01-23-2018 at 06:40 AM.
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Old 01-23-2018, 06:23 PM   #52
doctorevilbrain
 
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Default Re: Accumulators: A concept for GURPS Spaceships

What do you mean? Fuel is matter.
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Old 01-23-2018, 09:05 PM   #53
Johnny1A.2
 
Join Date: Feb 2007
Default Re: Accumulators: A concept for GURPS Spaceships

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Originally Posted by YankeeGamer View Post
That is more than "Pretty good." But Kinnison's ships still had accumulators beyond just power plants. IIRC, they even had them when total conversion was only used as an exciter for "Cosmic Power Screens," a starkly amazing power supply.
I know. It just isn't clear why they used them, unless, as I said, it was so they could deliver energy faster than the nuclear motors could do it, and for backup.


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Originally Posted by doctorevilbrain View Post
What do you mean? Fuel is matter.
Exactly my point.

If you have total-conversion reactors, then you can simply stuff the fuel bins with whatever is convenient to convert, you'd want something dense so as to pack a lot of mass into the smallest space, lead would make a dandy fuel under those conditions. So would gold, or osmium, or anything really dense. Lead just happens to be common and stable.

Which is the key point. Stability. If you can convert matter into energy conveniently, not just nuclear reactions but the whole shebang, then it's easiest to store your energy just as whatever matter your convert for fuel, it's energy-dense (25 gigawatt-hours/gram), and stable.

Twenty-five gigawatt-hours, charged into most storage technologies, is a bomb waiting to go off. Short that accumulator, or shoot it, or something, and BOOM. Twenty+ kilotons, almost half again bigger than Hiroshima. Twenty-five gigawatt-hours in the form of a gram of lead is very, very safe, under most conditions the chance of it exploding is nil.

So I have to assume that the accumulators most have some advantage. Maybe they can store energy even more densely per unit mass than matter can, maybe they can deliver their power faster (that strikes me as the most likely idea). Maybe it takes the reactor a second to convert a gram of 'x' into energy, and the accumulator can deliver its 25 gigawatt-hours in a millisecond. That could be handy sometimes.

Plus, of course, backup if the reactors fail.
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Old 01-23-2018, 09:27 PM   #54
Johnny1A.2
 
Join Date: Feb 2007
Default Re: Accumulators: A concept for GURPS Spaceships

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Originally Posted by YankeeGamer View Post
That is more than "Pretty good." But Kinnison's ships still had accumulators beyond just power plants. IIRC, they even had them when total conversion was only used as an exciter for "Cosmic Power Screens," a starkly amazing power supply.
Incidentally, the 'cosmic energy field' that Smith's characters tap into in those stories is 100% real. We call it 'starlight'. :lol:

Smith slides that one through by combining two facts and waiting to see who noticed. As he has a character note, any given star pours out the equivalent of at least hundreds of thousands of tons of mass converted into energy per second, there are billions of starts in a galaxy and billions of galaxies, so that energy is flowing out across the universe all the time.

Of course, that energy fills a universe so big that the energy per unit volume is starkly miniscule, unless the volume is at least many AU on a side and contains a star. So for the cosmic energy power systems to work, the intake volume for the fields must be starkly enormous, probably light-years across per ship, and efficiency must be low, so the fields have to be even bigger. (The ships don't black out the stars, after all, except by occultation.)

Now, if you can spread a spherical intake volume 100 light-years in diameter across galactic space, and soak up, say, .01% of the energy in that volume for use, and there are (let us say) about three thousand stars in the volume, (assuming a star for every 168 cubic light-years, which is one figure I've seen for local stellar density around Sol), and if we then assume for convenience that these stars are class M dwarfs like Proxima (most stars are), then we get (.0001* 3000 stars * 680000 tons (Proxima emits about .17 of Sol's output, which comes to about that) of matter converted per second)*, which gives our cosmic-energy-powered ship about 500,000 petawatts to burn.

Not bad for starlight, if you can just make your intake-field 100 light-years wide...

OTOH, if your intake fields are limited to mere AU rather than light-years, cosmic energy will work about as well as you'd expect an engine powered by starlight to work.

*ADDENDUM: I realized after I signed off last night that I had left out a factor, I was calculating based on the tons per second conversion rate in the stellar interiors, so to make the outcome correct I need to multiply by 3600, so instead of 500,000 petawatts, it's actually not quite 2 billion petawatts...
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Old 01-24-2018, 02:43 PM   #55
gruundehn
 
Join Date: Oct 2005
Default Re: Accumulators: A concept for GURPS Spaceships

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Originally Posted by YankeeGamer View Post
That is more than "Pretty good." But Kinnison's ships still had accumulators beyond just power plants. IIRC, they even had them when total conversion was only used as an exciter for "Cosmic Power Screens," a starkly amazing power supply.
IIRC, the accumulators used after cosmic energy became the power source were used to even out the energy flow, something capacitors do very well.
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Old 01-24-2018, 09:13 PM   #56
Johnny1A.2
 
Join Date: Feb 2007
Default Re: Accumulators: A concept for GURPS Spaceships

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IIRC, the accumulators used after cosmic energy became the power source were used to even out the energy flow, something capacitors do very well.
You could also use them to save on fuel. In Grey Lensman, it's mentioned that the Dauntless uses total-conversion power plants to drive the cosmic energy intake. You could instead use accumulator banks to do that, once you used the atomic motors to start the process at the beginning, you could store up some of the outside energy in your accumulators and then use it to drive the continuing intake, and turn off the atomic motors entirely.
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