Accumulators: A concept for GURPS Spaceships
 

Accumulators: A rough idea

In some science fiction, ships use batteries/accumulators. The Lensmen needed to be sure that the mighty Dauntless’s accumulators were full before reporting “Hot and Tight.” Star Fleet Battles—the batteries are vital. Honor Harrington’s “Superconducting loops” are very efficient batteries.
Real world submarines depend on batteries when submerged, unless they are nuclear boats. Modern spaceflight uses them, too.

Spaceship Accumulators could be useful. Instead of generating power points, they hold a certain number of “Power point hours.” Having stored power is useful for several things, depending on the universe. Anything that needs a LOT of power for a short time can benefit from accumulators. If entering hyperspace takes 5 power points for a moment, a 1 power point hour accumulator can give that blast of power, then be recharged at leisure—much more practical than including a massive 5 power point plant, if the ship never needs more than 1 or two power points at other times.

Other ships might run on engines, but fight using accumulators.

If you need to overload an engine to get more speed, but don’t want to overload the power plant—accumulators to the rescue.

Nuclear plants generate neutrino radiation; which, in some settings, can be detected. Run silently on the accumulators.

Accumulators are always ready, so if the power plant is offline for maintenance, the ship can still fire its weapons/

I would propose that accumulators cost an amount comparable to a similar power plant of the tech level and type, and have power point hours equal to the power points the plant puts out. They are, of course, volatile systems.

Ships that only have low power systems (Zero power points) can charge accumulators, but it takes a formidably long time—probably DAYS per power point-hour. The small power plants can dedicate spare watts to the accumulators.

This is just a very rough idea I had; I have not done any number crunching to see how it balances out—might need to be tweaked seriously in terms of cost, power point-hours, or anything else. Have fun; if anyone thinks it needs changes, please speak up.

(Now a ship with an oversized spinal mount, taking 9 spaces, might be able to fire it.!)

Re: Accumulators: A concept for GURPS Spaceships
 

I agree with your basic concept; however.

Energy storage capacity and discharge rate are pretty much inversely proportional. Capacitors discharge quickly (but can't store a lot) and batteries store a lot (but can't discharge quickly).

A superconducting loop is a capacitor, not a battery.

With that said power cells which start appearing at TL9+ seem to have solved this issue, having discharge rates fast enough for rapid fire lasers and energy capacity in excess of any modern battery while only being trivially heavier.

Massive storage of power and rapid discharge at the rate required for energy weapons, etc, will be at such high levels of power that you will be generating as much if not more detectable gauss energy and radio emissions, so I would dispose any notes about it being more stealthy to use the power reserve.

Re: Accumulators: A concept for GURPS Spaceships
 

I was trying to keep it simple, without needing to distinguish between types of storage. (Call it ultra-tech equipment.)

Using the Accumulators to fire won't be stealthy, but they have no emissions until the gun is fired, keeping the emissions low until that first blast from a spinal gun. Reactors will radiate when idling, as long as something is reacting--they don't really have an "instant on" function.

They're still useful for a hyperdrive that needs a massive jolt to enter hyperspace, or ships that don't usually need lots of power, but when they need it they need it NOW, or need LOTS for a few minutes.

I'm sure that cloaking will be much more effective if there's no reactor running, too.

Re: Accumulators: A concept for GURPS Spaceships
 

If the reactor can be turned on and off at will (which is not the case for any current atomic reactor), then it will have no problem turning down to enter 'stealth mode' and only providing the bare requirements for life-support and the cloaking device while reducing its emissions to near-nil in the process (unless the stealth system is particularly hungry, but then you go back to the stored energy releasing so much gauss and EM that its a beacon in and of itself)

Re: Accumulators: A concept for GURPS Spaceships
 

I'm assuming that a reactor takes time to power up, so Instant On is very valuable.

Re: Accumulators: A concept for GURPS Spaceships
 

From my experience as an electronics tech, capacitors can hold a charge only for a small time as they will "bleed" their charge off continually. Also, find yourself a decent basic electronics principles book and notice just how big a capacitor has to be to hold a decent charge. I do not think "Doc" Smith ever mentioned just how big his spaceships were but unless the Lensmen found a way to modify the laws of physics as we presently understand them, the Dauntless would be close to the size of our Moon and most of the interior space would be capacitors in order to power effective weapons.

Re: Accumulators: A concept for GURPS Spaceships
 

Doc did indeed modify the laws of physics as we understand them. That was one of the things that made him a Master of Superscience!

The one time specific real world power numbers were mentioned was early in Triplanetary and the power cell of a blaster pistol was exploding and releasing all the many kw/hours it held. It was much more energy than even a Gurps 3e superscience power cell.

No specific numbers on ship size but the Dauntless was on the order of hundreds of yards long. It's weapons were not powered by accumulators but rather by directly tapping into cosmic energy.

There were accumulators in Spacehounds of IPC but superscience was rife in that book too.

Re: Accumulators: A concept for GURPS Spaceships
 

Even if the reactor is just ticking over, it's still likely spitting out either neutrinos or anti-neutrinos.

Re: Accumulators: A concept for GURPS Spaceships
 

By the time of the Dauntless, Civilization's technology and physics were both well past our level. Think Vingian singularity level, though without computers.

Re: Accumulators: A concept for GURPS Spaceships
 

It also carried total-conversion reactors, and in this case Smith gave hard numbers. Each mass converter could turn 400 lbs. per hour into useful energy, which means each converter had an output of 4.5 petawatts. When the cosmic energy collectors were running, that was amplified by a factor of 100,000 to 1, so the minimum energy potential of the Dauntless was 454 million terawatts. That's over 2600 times the energy the Earth intercepts from the Sun.

Interestingly, unlike some writers, Smith was not completely unaware of the implications of this kind of power. The Patrol and the Boskonians could and did volatize entire planets, reshape star systems, etc. OTOH, the effects on daily life were limited, and there are some interesting questions about how this kind of power was controlled absent computers and related tech.

Re: Accumulators: A concept for GURPS Spaceships
 

In fact the basic TL9 power cells have way less energy/weight than the best current day batteries(late TL 8), but indeed much higher discharge rates. In fact a TL 9 cell is about equal to a high end current LI battery in total energy, but can get it out really fast.

So the power cells have not solved the issue, instead they have made the default to be fast discharge cell instead of a maximum total energy one.

Re: Accumulators: A concept for GURPS Spaceships
 

It seems the accumulators are space opera science, or supersicence. It was the Britania that used Accumulators. (Also, when Kinnison and Van Bursic were marooned on Delgon, they used the output of an ATOMIC POWER PLANT for hours to recharge their power armor and blasters.

They may not belong in rivet-counting stories, but there's room for Space Opera here.

Re: Accumulators: A concept for GURPS Spaceships
 

Which is in fact realistic, given the tech. The nuke plant they were tapping was a primitive one by their standards, probably something akin to ours today, and the devices they were recharging could store immense amounts of energy, they had to be able to do so to do what they did.

Re: Accumulators: A concept for GURPS Spaceships
 

I vaguely recall that the power busbars in ships would be several feet thick. Given how rich Civilization was, wouldn't it be better to spring for silver to get the resistance loss and waste heat down?

Re: Accumulators: A concept for GURPS Spaceships
 

This is an area where Smith dodged reality while addressing it. In reality, silver or copper either one would not be enough, the energy loads passing through either would have vaporized the bus bars and the whole ship too.

Later in the same story, the Patrol comes into contact with a society that knows how to make room-temp superconductors better than anything we have now, but in fact, for their ships and machines to work at all, they'd need superconductors to handle those power loads. They'd absolutely have to have superconductors to make a Dauntless at all.

After all, if you're using multi-petawatt power levels, even if you're running at 99.9% efficiency somehow, that remaining .1% loss adds up to terawatts of heat in a machine comparable in size to a modern naval warship.

Copper, silver, aluminum, any of them would have resistance losses well above .1%.

Re: Accumulators: A concept for GURPS Spaceships
 

OK, I knew what I was talking about in my first post but it seems I forgot that no one else knew the specifics I left out because they were not needed. After all, you are all electronic techs, right?

The measure of a capacitor is the Farad. A farad is the ability to store a specific number of electrons - a coulomb, or 6.242 x 10 to the 18 electrons. Most capacitors are rated in micro-farads and are about the size of the fingernail of your pinky, or maybe as large as your thumb.

So, to get the charge necessary, as implied in the stories, the capacitors would have to be on the order of Giga-farads if not larger. So, either the capacitors are each larger than Manhattan, with more than one available to allow for multiple shots, or the scientists of that era found a way to store a coulomb of electrons in a capacitor the size of one today that stores a Nano-coulomb.

Capacitors "bleed" all the time as electrons flow away from the capacitor into the circuit. The larger the capacitor the more the bleed. Usually this is countered by constantly charging the capacitor. Capacitors are often used to smooth out the ripples in a DC circuit, where the current above a certain value is shunted into the capacitor and the capacitor bleed some current into the circuit when the DC value is lower than wanted. So, unless these huge capacitors can be charged almost instantly, the engines have to constantly replace the bleed amount.

Re: Accumulators: A concept for GURPS Spaceships
 

Just for some real world numbers on the sort of sizes your going to need:

The already existing supercapacitor:
(https://en.wikipedia.org/wiki/Supercapacitor )

Assuming that we don't make any further strides in this technology in terms of energy density (which may or may not be possible, my understanding is we are quite close to the theoretical limits already) you store ~200 wh/m^3 in a supercap. To get to a GWh of power, you would therefore need 5km^3 of space for your 'accumulator'

Superconducting loop magnetic energy storage already is a thing (https://en.wikipedia.org/wiki/Superc...energy_storage ); admittedly for niche applications right now, but apparently we could already achieve 1 GWh of energy with 160km of superconducing coil assuming you aren't doing anything fancy with stacking small coils inside large coils you would need 7.345km^3 (assuming 130mm spacing between each loop). Give that massive size for the loop, I think we can safely assume ten loops are possible (so one largest loop and then incrementally smaller ones inside), lets assume that we can do this a hundred times (it would be more like 300-500 loops because each loop would have a smaller distance than the first, giving about 130mm between each loop)- we are looking at 73.45m^3 of space way better than the supercap above, but requiring superconductors, cooling, conversions, enough teslas to rip the iron out of your body if you were unfortunately next to it (which also precludes it from being supported by anything magnetic, or being next to structural components of the ship, and something that strains under lorentez forces with every discharge, and any damage to the not very strong ceramics at supercooled temperatures which are supporting the whole mess results in an instantaneous and catastrophic discharge that turns the whole thing into a self-propelling rail gun projecile with 1 GWh of power. IE this practically needs a LOT of shielding (non-magnetic shielding), as well as support infrastructure, and probably some thoughts about causing it to catastrophically fail AWAY from the ship rather than INTO it, which will radically increase its size.

Re: Accumulators: A concept for GURPS Spaceships
 

The thing to remember about a Smithian accumulator is that it isn't a capacitor or a battery. It's a totally different technology, probably based on physics we don't understand, like a lot of the rest of their tech.

An accumulator is defined not by how it works, but by what it does, i.e. store large amounts of energy with the ability to release it very fast. How it does it matters less than what it does.

How much energy does a Smithian accumulator store? He never gives hard figures, but lower bounds can be estimated by observing what the technology does. The answer is 'a freakin' lot'. They can power hand weaponry with more than enough juice to vaporize large masses like humans, or sections of walls. (It takes far more energy to vaporize a human than it does to kill one.)

The shipboard accumulators can store significant amounts of energy relative to their total-conversion based power plants.

Remember the old Star Trek TOS trope of the phase pistol set to turn into a bomb? There were a couple of incidents where it was shown that this could be done, and Kirk says at one point (paraphrasing) that such a pistol bomb could have blown the side of the ship out if they hadn't stopped it.

That's completely realistic, given the displayed performance of the phaser pistols (rapid vaporization of large masses, etc.). That much energy packed into a small space will make a dandy bomb if it gets released instantly.

The Smithian accumulators have similar storage densities, or higher.

Re: Accumulators: A concept for GURPS Spaceships
 

That's interesting.

It also touches on something important: any form of high-density energy storage, if the physics allows for it to come out fast, is a potential bomb.

Re: Accumulators: A concept for GURPS Spaceships
 

Just like some Samsung phones today are potential fires, and these are low tech (compared to space) and small.
If it isn't designed to come out fast, smashing it should get it to come out. That's why I listed Smithian Accumulators as volatile systems.

Re: Accumulators: A concept for GURPS Spaceships
 

You are not making your case that accumulators are neither capacitors not batteries. Capacitors are active storage devices and batteries are passive ones. Unless accumulators store energy in some fashion that is neither active nor passive, they are one or the other.

Re: Accumulators: A concept for GURPS Spaceships
 

A superconducting induction ring is neither a capacitor nor a battery, but it stores energy.

Re: Accumulators: A concept for GURPS Spaceships
 

I should perhaps have said that they were neither capacitors nor batteries as we know those. You could call them batteries because they can store energy for long periods safely or capacitors for their ability to deliver that power fast, but they overlap the performance of both current technologies.

A Smithian accumulator could be called either a battery or an accumulator in sort of the same sense that an automobile could be called either a horseless carriage or a mechanical horse.

Re: Accumulators: A concept for GURPS Spaceships
 

I am not familiar with that technology. Does the device have to be part of a circuit or can it be left by itself? If it has to be part of a circuit, it is a capacitor. If it can be removed from the charging circuit and stored, it is a battery.

The function does not change even when the technology does.

Re: Accumulators: A concept for GURPS Spaceships
 

'Battery' and 'capacitor' are not as abstract terms as you seem to want them to be.

Also, a capacitor can be removed from the charging circuit and stored. They do tend to lose their charge over time, though that might be more a feature of modern tiny ones than bulkier types like leyden jars. But then some electrochemical batteries also break down in storage...

Re: Accumulators: A concept for GURPS Spaceships
 

I don't understand the passive / active distinction. A capacitor stores energy in an electric field. A battery stores electrical energy as chemical energy. If anything, the battery seems the more "active" of the two in that more has to happen to get electricity back out. But they both have to change something about their state.

"Accumulator" is a general term for something that stores energy; by that definition, both batteries and capacitors are types of (electrical) accumulator. I've also seen that term used for non-electrical energy storage, as in hydraulic systems, so it seems the broadest of the three, and thus appropriate enough either for purposes of the OP or of Doc Smith.

Re: Accumulators: A concept for GURPS Spaceships
 

I am not using the terms in any abstract sense but in a technical sense. A capacitor must be kept charged actively in that current must always be supplied in order for the charge to stay. A battery does not need constant recharging. Yes, there are capacitors that can store a charge outside of a circuit but not generally, old style Leiden jars hold a charge, for example, but not over a long period of time. Hours, or maybe days rather than years or even decades.

There are other differences between the two types of electrical storage but the need to recharge over a short period rather than a long period is the one I started with and stay with.

Re: Accumulators: A concept for GURPS Spaceships
 

A capacitor stores electrical energy on a physical surface and a battery stores electrical charge (sort of) in a chemical solution. I say sort of because a battery does not store electrical energy but chemical energy which due to chemical action, releases electrical energy.

When my father got his electrical engineering degree, accumulator was the technical term for what is now known as a capacitor. The term has broadened its meaning over the years. I grew up with that narrower usage and that may affect my thinking even though I spent decades as an electronics technician where the term capacitor was used exclusively.

Re: Accumulators: A concept for GURPS Spaceships
 

There may be some technical field where that is the formal usage, but I have never seen it before.

...And what batteries are you expecting to retain EMF for decades?

Capacitors have rather important technical features other than holding charge but being prone to bleed. I think most places where a capacitor is used, substituting a battery would make the circuit non-functional...
This, on the other hand, suggests a definition of capacitor (and battery) which (A) aligns with every definition I've ever seen anywhere and (B) makes nonsense of your assertion in post #24. Batteries and capacitors are (or can be used as) energy storage technologies, but not all energy storage technologies need to be characterized as either battery or capacitor.

The aforementioned superconducting induction ring stores energy in a current and induced magnetic field the same way a conventional inductor does, but because it's superconducting it doesn't rapidly lose the stored energy to resistance in the conducting element.

Re: Accumulators: A concept for GURPS Spaceships
 

I was originally thinking of space opera, in particular, Lensman style accumulators, that store energy for use in a battle, or anything else, as dramatically necessary. It seems that, if I want the "accumulators" to do both, it would need to include both batteries for long term storage, and capacitors for firing the weapons, after charging them from the batteries.

Goal is to have extra energy for whatever needs it, without extra reactors, be it for firing a weapon, entering hyperspace when hyperspace needs 5 power points and a reactor has one, but only need those 5 power points for a moment...

Medium hard science fiction to Space Opera--and I learned a lot here.

I know that model railroad locomotives use a capacitor on some fancier DCC (Digital Command Control--fancy electronic comtrol for model trains) to keep it going over short sections of dead track. Beyond that, I didn't really know much about capacitors or batteries.

Re: Accumulators: A concept for GURPS Spaceships
 

This is the kind of thing that, at Spaceships resolution, is most likely just an integral part of the hyperdrive. Just as many weapons likely incorporate on-mount capacitors to translate between steady reactor power in and intense spike power needed for firing, below the resolution of the system.

Re: Accumulators: A concept for GURPS Spaceships
 

I think they would have to be background specific. If you are running a space opera game go ahead and create an Accumulator system that stores X power points where X is whatever doesn't break your game. This will skew your ship designs into those with smaller reactors, at least for short engagements. Smaller ships with limited endurance like fighters will probably favor accumulators over reactors.

Re: Accumulators: A concept for GURPS Spaceships
 

[QUOTE=Ulzgoroth;2146905]There may be some

...And what batteries are you expecting to retain EMF for decades?

[QUOTE]

Neither batteries nor capacitors store EMF (voltage) they both store electrons. The only electrical or electronic device that stores EMF is an inductor (coil) which stores voltage in the magnetic field generated when current passes through the coil.

Re: Accumulators: A concept for GURPS Spaceships
 

The Vingean singularity, specifically, is exponential growth of self-modifying code. How does that work without computers?

Re: Accumulators: A concept for GURPS Spaceships
 

Batteries sort of store electrons, but they generate EMF.

(Though at sufficiently high current values it must be more complicated than that.)

Re: Accumulators: A concept for GURPS Spaceships
 

Present-day chemical batteries can be thought of as having their own internal circuit - sort of, in a simplistic way. The electrons are stored, but the chemical action of the battery releases them at two levels. The low-level release rate is when there is no external circuit and thus the battery charge can last years, if not decades. If there is an external circuit, the battery releases a steady stream of electrons and the total circuit resistance opposes that release; thus, by Ohm's Law (E=IR or more accurately I=E/R) voltage happens. Any EMF generated is a byproduct of the fact that the battery is releasing electrons.

Re: Accumulators: A concept for GURPS Spaceships
 

Comparing an aircraft engine power/weight ratio with modern battery storage capacities, and considering how Spaceships systems are put together (IC engine systems include some fuel), I get an back-of-the-envelope result of 20-30 minutes of output from modern batteries at one power point (i.e. they can produce the same output as an IC engine+ hours of fuel for 20-30 minutes). If one assumes a heavier IC engine (and given aircraft engines operate in an environment that's easy to dump heat in, this is reasonable) and better batteries, an hour might be reasonable or perhaps two power points for 20 minutes (the longest Spaceships combat turn). Higher TLs would increase duration, not output, to be consistent with the way other power plants work.

Assuming a TL^ 'super battery' with more capacity is the logical way around this fairly small capacity. I expect that to fill the role the OP wants they'd have high output rather than high duration.

Re: Accumulators: A concept for GURPS Spaceships
 

It's probably meant to refer to exponential growth of technology generally and not just computers They have that in Lensman.

Note that in the "conventional" Singularity it's just sort of thrown in that when the smarter than human computers aren't designing new computers even smarter than themselves in even less time than it took themselves to be designed they sort of solve every question in physics, cosmology and Science! generally as a sort of side effect to what was really important.

Re: Accumulators: A concept for GURPS Spaceships
 

That's why I said 'vingean singularity level'.

That's the form Vinge thought it would take, but the idea of the singularity is that it's a cutoff point in history, beyond which we can't predict anything meaningful because technology has advanced to the point of obviating everything in our experience. The super-duper-magical AIs might understand the universe so well, after exponential increases in intelligence, that they could make anything happen, leaving us like chimps dealing with humans, or worse.

I have never for a moment believed that the pure Vingean 'computerageddon' was a valid concept, not 25 years ago and not now. Though I've seen reasonable arguments that the period from ~1840 to 1950 could be seen as a transport/communications/warfare 'singularity' from the POV of previous time.

But the technology of Civilization/Boskonia, by the time of Kimball Kinnison, is so advanced in terms of travel, weaponry, energy sources, etc. that it could reasonably said that the characters have access to god-like (with small 'g') power. They can move entire planets from galaxy to galaxy more easily than we can move a plane-load of cargo from North America to Europe, and volatizing entire planets is a relatively trivial exercise. The power of the Death Star is easily within the reach of either side of that war, in far more convenient and portable form. Their individual space suits have interplanetary capability on their own power, and if they really want to do it they could make them interstellar capable, it's just a pointless exercise to do so.

Now none of this seems to affect daily much, but this is space opera, after all, though more thoughtful space opera than most.

Re: Accumulators: A concept for GURPS Spaceships
 

Are you seriously trying to assert that batteries generate fixed current regardless of the circuit they're in? You have to know that's completely inaccurate. EDIT: That's blatant violation of conservation of energy stuff.

Re: Accumulators: A concept for GURPS Spaceships
 

Why specifically Vinge's singularity and not just the singularity? How is it like Vinge's model and not Kurtzweil's or Bolstrom's?

Re: Accumulators: A concept for GURPS Spaceships
 

It's actually the other way around. The metals/salts in the battery have an inherent voltage (EMF) differential dependent on the chemistry of the combination of salt/ions/metals/acids. The current flow depends on the load attached across the voltage. If you put a wire across the battery then the only 'load' is the internal resistance of the battery, which is quite low. As a result, LOTS of current flows, usually heating up the wire and making it combust, or simply get hot enough to melt the guts of the battery.
In electronics you pretty much always have a voltage differential and the actual current drawn depends on the load. You can create 'current sources' but they are basically self-modulating loads that balance out resistance with the real load so the real load sees a constant current.

Re: Accumulators: A concept for GURPS Spaceships
 

Mostly just because Vinge is the name most generally associated with the Singularity idea in SFnal circles, he's the name that comes to mind for me rather than the others.

Re: Accumulators: A concept for GURPS Spaceships
 

No. The chemical composition of chemical batteries will have varying current based upon the resistance of the external circuit. But the chemical action produces electrons not voltage. Granted, by Ohm's Law, the three are highly interconnected but the chemical action produces electrons.

Re: Accumulators: A concept for GURPS Spaceships
 

I am an electronics technician, not an engineer. This is what I was taught.

Re: Accumulators: A concept for GURPS Spaceships
 

That's true in a sense, but it's a rather tortured sense. The chemical action 'produces' (at one end, 'consumes' at the other) electrons to (and from) the electrodes. But the reactions also point to a specific electrochemical, and thus electrical, potential.

It should be fairly obvious that the chemistry in a battery doesn't have any direct dependency on the resistance of the external circuit. What the resistance does is determine (in combination with the voltage) a rate limit on the flow of electrons which is (under typical conditions) the rate-limiting step in the battery reactions.

Re: Accumulators: A concept for GURPS Spaceships
 

I'm an engineer, but I hung out with the technicians running the labs a lot when I did my undergrad degree. I learned an awful lot of practical skills from them that weren't taught in the classroom.

Re: Accumulators: A concept for GURPS Spaceships
 

Getting back to Accumulators, it seems the only pseudo-realistic tech that makes sense is superconducting loops. Anything else requires a fair bit of handwaving to explain the energy density and discharge rates. I also wonder if star-trek style plasma could do the job? Maybe store the plasma in rings and draw the power down as you need it. Could use superconductors to help with efficient confinement of the plasma to generate containment fields...?

Re: Accumulators: A concept for GURPS Spaceships
 

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.

Re: Accumulators: A concept for GURPS Spaceships
 

Apparently the replicators in Star Trek fed off a stock of generic matter rather than trying to create matter from energy from scratch. The generic matter was reconstructed by the replicator which was much less expensive energy-wise. Storing fuel as matter for total conversion seems a similar concept.

Re: Accumulators: A concept for GURPS Spaceships
 

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.

Re: Accumulators: A concept for GURPS Spaceships
 

What do you mean? Fuel is matter.

Re: Accumulators: A concept for GURPS Spaceships
 

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.


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.

Re: Accumulators: A concept for GURPS Spaceships
 

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...

Re: Accumulators: A concept for GURPS Spaceships
 

IIRC, the accumulators used after cosmic energy became the power source were used to even out the energy flow, something capacitors do very well.

Re: Accumulators: A concept for GURPS Spaceships
 

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.