Jump Drive Powering

[phavoc]

Has anyone ever thought about charging the jump drive from a station or planetary starport instead of having to generate the power internally right before jump? As best as I can tell, you use your fusion plant to power up your capacitors, then you dump all the energy at once into your jump drive.

But it would be much more effecient to have massive powerplants that just dumped power into a starship (or charged their own capacitors then dumped it from one capacitor to the ship) instead of running around with your own overly-large powerplant. Military ships I could see would probably not subscribe to this design philosphy, but civilian ones would.

 

[dmccoy1693]

Neat idea. Only problem I can see is that the PP has to deliver a certain amount of energy for a full week. That strikes me as either requiring some massive capacitors or is not very practical. However, for a teleport drive that takes you where you need to go instantly, I could definitely see that.

 

[AndrewW]

You need to have some distance as well to make the jump so this is going to require a lot of storage for the energy on the ship itself. For the regular jump drive it's not use instantly and forget. By the time you add the tonnage for the capacitors for this don't see that working all that well. Now if you wanted jump drives that just needed jump starting and only used a small amount of energy after that to maintain the jump field it may be practical and allowed the energy to be stored in the jump drive itself rather then requiring extra capacitors for this. Or just use a new form of drive.

 

[phavoc]

You need to have some distance as well to make the jump so this is going to require a lot of storage for the energy on the ship itself. For the regular jump drive it's not use instantly and forget. By the time you add the tonnage for the capacitors for this don't see that working all that well. Now if you wanted jump drives that just needed jump starting and only used a small amount of energy after that to maintain the jump field it may be practical and allowed the energy to be stored in the jump drive itself rather then requiring extra capacitors for this. Or just use a new form of drive.

Yes, I'm cognizant of the 100 diameter rule for safe jumping. What I was talking about was reducing the tonnage required for a reactor to power a jump drive. As I understand the rules your reactor doesn't immediately generate all the power - it has to generate the energy and burn up the fuel prior to the jump occuring. I'm not sure if the old Starship Operations book talks about this or not. I don't have my copy with me...

 

[CosmicGamer]

Even if this is possible, the ship would be limited in where it could go because of its need for recharging facilities.

 

[dmccoy1693]

Even if this is possible, the ship would be limited in where it could go because of its need for recharging facilities.

You could just leave the PP run at full for a while while it is sitting on the planet/station to recharge the capacitors

 

[hdan]

I thought that in MGT the JDrive fuel was to inflate the "pocket universe" jump bubble? I rather like the image of ships blowing up "bubbles of realspace" and drifting through higher dimensional J-Space like hot air balloons.

 

[BP]

I thought that in MGT the JDrive fuel was to inflate the "pocket universe" jump bubble? I rather like the image of ships blowing up "bubbles of realspace" and drifting through higher dimensional J-Space like hot air balloons.

True - but this topic didn't specifically refer to Jump fuel - rather Power Plant size (and thus P.P. fuel).

The Divert Power section of Core mentions '...Jump Drive requires a tremendous amount of power to function...' and since ships don't just pop out of Jump early due to power loss, one could presume the idea is that the bulk of that power is needed during initiation of the Jump...
Jump capacitors are mentioned in High Guard in relation to Black Globes, though I don't recall any other details anywhere else.

I think the idea is to free up P.P. tonnage and fuel. P.P. are also not cheap - 80% cost of Jump drives and twice the cost of Manuever. For commercial operations on well established routes, but requiring higher jumps and little thrust, this might be viable - reducing staship capital and increasing cargo space. Of course, one would need to figure out the standard rates for this power.

The standard heavy frieghter (a J-2, 1G design) would only save less than 3% additional cargo (but almost 9% ship cost). Now if that ship needed to be a Jump-3 (L) :

• That would be +15 tons for J-Drive +100 tons J-fuel and +11 tons P.P. with +6 tons fuel, reducing its 552 tons cargo by 132 tons.
  If the P.P. was only E rated (for M-Drive) then that would shave off 30 tons (and 44MCr) or 7% more cargo (for J-3) and 13% less capital.

Higher Jump ranges would be even more attractive. So yes this though has some merit.

The real issue might be how long Jump Capacitors could remain charged - but if refuel point is already outside 100 dia limit, then shouldn't be a problem - adding extra capacitor wouldn't significantly impact savings. I think it might merit increasing Mis-Jump/Jump failure percentages though.

 

[omegar]

it could also allow two jumps in quick succession.

so a J-1 ship would be able to a star J2 away. would be useful for ships that are limited to the mains allowing them to get across gaps.

 

[AndrewW]

it could also allow two jumps in quick succession.

so a J-1 ship would be able to a star J2 away. would be useful for ships that are limited to the mains allowing them to get across gaps.

A J-1 ship could do that now if it carries enough fuel for 2 Jump-1's. Most of what is needed for this is fuel not power. An existing power plant capable of supply enough power for one J-1 can supply enough for two J-1's just as easily.

 

[phavoc]

Yea, the topic had two intended consequences:

1) Is the concept reasonable, and thus able to be used or adapted to the existing game universe. So far so good...

and

2) IF the concept is sound and reasonable, it would greatly change ship design for ships that travelled regular trade corridors and had no need to go out into the wilds. Freighters and passenger liners would just need to stop off at a charging station prior to jump and be on their happy way. All of the space allocated to jump fuel could be re-tasked towards something else. And the cost associated with a larger power-plant than required could be saved or put back into a bigger jump drive to extend ranges.

Now one thing I'm still not clear on is exactly WHERE the energy is stored prior to the jump. Ships designed under existing rules already must have onboard capacitors sufficient to store the energy prior to being fed to the jump drive, unless somehow the drive itself is also the capacitor... As someone said before, you could simply install capacitors instead of larger fuel tanks/power plants to give your ship extended jump range.

Thanks for all the ideas!

 

[mmbutter]

The idea sounds workable, but capacitors are only capable of short term energy storage - that's why they're not called "batteries". Of course, we could postulate technological improvements. Capacitors are designed to charge and discharge very rapidly.

 

[phavoc]

The idea sounds workable, but capacitors are only capable of short term energy storage - that's why they're not called "batteries". Of course, we could postulate technological improvements. Capacitors are designed to charge and discharge very rapidly.

I'm not an electrical engineer, but I do know capacitors have the ability to store energy until its discharged. They aren't like a battery because they are designed to dump their energy in an instant, whereas a battery slowly discharges over time (hint... never buy a flashlight that uses capacitors as the powering mechanism....

According to canon, jump power plants charge the jump capacitors, and when they are fully charged then they dump all of their energy into the jump drive to activate the jump. If it was reverse, you should be able to use the powerplant itself to kick off the jump.

Or so my understanding of all of this says.

 

[AndrewW]

I'm not an electrical engineer, but I do know capacitors have the ability to store energy until its discharged. They aren't like a battery because they are designed to dump their energy in an instant, whereas a battery slowly discharges over time (hint... never buy a flashlight that uses capacitors as the powering mechanism....

And if you do don't look into the flash of the beam.

 

[mmbutter]

but I do know capacitors have the ability to store energy until its discharged. They aren't like a battery because they are designed to dump their energy in an instant, whereas a battery slowly discharges over time (hint... never buy a flashlight that uses capacitors as the powering mechanism....

Well, they can be designed to release their energy slowly (via a circuit). However, the "store energy until it's discharged" part is for a "perfect" capacitor. We have yet to find one of those. Imperfections in manufacturing, temperature, problems with the electrolyte, etc all cause losses over time. For some types of capacitors, even sound waves will cause the capacitors to discharge.

 

[phavoc]

but I do know capacitors have the ability to store energy until its discharged. They aren't like a battery because they are designed to dump their energy in an instant, whereas a battery slowly discharges over time (hint... never buy a flashlight that uses capacitors as the powering mechanism....

Well, they can be designed to release their energy slowly (via a circuit). However, the "store energy until it's discharged" part is for a "perfect" capacitor. We have yet to find one of those. Imperfections in manufacturing, temperature, problems with the electrolyte, etc all cause losses over time. For some types of capacitors, even sound waves will cause the capacitors to discharge.

Hey, it's the future!!! Everything works better! Even Windows Super-Professional version for Starships only blue-screens every 10th jump!

 

[rje]

My first opinion: this is similar to the drop tanks issue. If you have drop tanks, then you can power up for jump, drop the tanks, and jump at a reduced volume, thereby jumping further.

As mentioned, an "external charging station" changes the dynamics of ship designs, and so in my second opinion there has to be a consequence for this sort of setup which allows drop tanks and yet does not typically allow a power station.

My third opinion is that "jump capacitors" are "leaky", and ships don't have enough time to get 100 diameters from an external fuel source, so they would be forced to jump within the 100D limit or else lose the energy. My fourth opinion is that, when jumping 100D from something else, the largest object "wins", and all other objects suffer damage, mishaps, disintegration, or something like that.

My fifth opinion is that once a ship is in jumpspace, a minimal power plant is still needed to maintain the jump field and ship systems.

 

[phavoc]

My first opinion: this is similar to the drop tanks issue. If you have drop tanks, then you can power up for jump, drop the tanks, and jump at a reduced volume, thereby jumping further.

It's not similar to drop tanks because drop tanks add mass to the ship. Your jump drive still needs to have the capability of jumping the total mass of the ship, and your power plant still needs to be sized to power the jump drive.

As mentioned, an "external charging station" changes the dynamics of ship designs, and so in my second opinion there has to be a consequence for this sort of setup which allows drop tanks and yet does not typically allow a power station.

Yes, it does change the concept, by minimize the mass of the power plant and significantly reducing the requirement for on-board fuel storage.

My third opinion is that "jump capacitors" are "leaky", and ships don't have enough time to get 100 diameters from an external fuel source, so they would be forced to jump within the 100D limit or else lose the energy. My fourth opinion is that, when jumping 100D from something else, the largest object "wins", and all other objects suffer damage, mishaps, disintegration, or something like that.

I suppose that could be a possibility (i.e. "leaky" capacitors). Perhaps you would need to increase the number of capacitors, or have the power plant dumping excess megawatts continually into the capacitors to retain a large enough charge.

As far as jumping within 100d of another object, that is all based on the size (or mass?) of the object. Jumping less than 100D doesn't affect anything other than the ship doing the jumping. The closer you are the higher the risk there might be a mis-jump.

My fifth opinion is that once a ship is in jumpspace, a minimal power plant is still needed to maintain the jump field and ship systems.

Agreed. Ships will require power no matter what. But if you could reduce the size of the power plant to provide energy only to the maneuver drive and other internal systems like life-support, then your power plant would not need to be nearly as large.

 

[BP]

... intended consequences:
... would greatly change ship design for ships that travelled regular trade corridors and had no need to go out into the wilds.

Read my prior post - change yes, greatly no. :wink:

...All of the space allocated to jump fuel could be re-tasked towards something else.

Sorry - re-read page 141 of the Core Rulebook about Jump Travel. The Jump fuel is for the 'Jump bubble'.
The only time extra Power Plant fuel is needed is if the Jump Drive rating is higher than the Manoeuvres'.

... And the cost associated with a larger power-plant than required could be saved or put back into a bigger jump drive to extend ranges.

Extending cargo capacity - Jump range extensions would probably still reduce cargo (though, I haven't run numbers for capital sized ships). My prior post gave examples of this. Of course that only works when Jump rating is higher than Manoeuvres.

Now one thing I'm still not clear on is exactly WHERE the energy is stored prior to the jump. Ships designed under existing rules already must have onboard capacitors sufficient to store the energy prior to being fed to the jump drive, unless somehow the drive itself is also the capacitor... As someone said before, you could simply install capacitors instead of larger fuel tanks/power plants to give your ship extended jump range.

High Guard spells out the tonnage (and Energy Points) related to the Jump Capacitors. It also provides cost and tonnage for adding additional capacitors. (This is in relation to the Black Globes).

Adding capacitors to avoid higher rating Power Plant? Since Jump drives have enough capacitors already - there would be no need to add more, except to compensate for leakage... (and that costs tonnage, MCr and would need more P.P. fuel - offseting a good % of savings).

Capacitors leak charge - likely discharging fast enough that slowly charging more at a lower power rating is a loosing proposition. I.e., by the time the extra capacitors are charged the original ones are discharged by an equal amount.

So, in effect - a certain rating P.P. could only charge up X amount of capacitors in any given time span. This would be a reasonable explanation for requiring higher rated P.P. in the first place.

It also means that charging the capacitors planet side is probably useless (100 dia rule) which means the P.P. providing power won't be near a fuel source - meaning a higher cost (fuel must be shipped) for the initial source power. So, while more cargo could be carried (in certain situations), it would be done at a higher cost.

Of course, you could ignore the Jump Bubble IYTU and eliminate this problem. Or provide for smaller Power Plants (note HG TL mods already do and Core antimatter P.P. eliminate extra P.P. fuel). Or whatever...

 

[phavoc]

... intended consequences:
... would greatly change ship design for ships that travelled regular trade corridors and had no need to go out into the wilds.

Read my prior post - change yes, greatly no. :wink:

...All of the space allocated to jump fuel could be re-tasked towards something else.

Sorry - re-read page 141 of the Core Rulebook about Jump Travel. The Jump fuel is for the 'Jump bubble'.
The only time extra Power Plant fuel is needed is if the Jump Drive rating is higher than the Manoeuvres'.

Ok, went back to core rulebook and I see the entry about the hydrogen being required to be injected into the "alternate" universe where the ship exists until it exits.

Now, with that being said, drop tanks would make more sense for vessels, since they are relatively tiny (for the 100d issue) and the ship would not need to carry the fuel mass internally. According to HG it says at TL14 and up the drop tanks always survive the jump wake of the jumping ship and can be re-used.

Gonna have to think about his one some more. Thanks for pointing that out to me though.