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Author Topic: Safe superjump?  (Read 5352 times)

The_Caveman

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Re: Safe superjump?
« Reply #30 on: 01 August 2019, 09:39:49 »
Might be 30 LY is close to the physical limit for a germanium core. Some property that is intrinsic to germanium at an atomic level, such that technology can't do much to get around it (like how we'll never change the density of iron, we're just stuck with what nature gave us).

You can hypothetically build more advanced cores with longer ranges but they need materials more exotic than germanium. Maybe some rare lanthanide, or heaven help you if it's astatine. Or non-baryonic matter. No one has built such a core because assembling enough of the raw materials in one place would have bankrupted the Star League.
Half the fun of BattleTech is the mental gymnastics required to scientifically rationalize design choices made decades ago entirely based on the Rule of Cool.

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Kovax

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Re: Safe superjump?
« Reply #31 on: 01 August 2019, 12:14:37 »
Research normally does not happen smoothly over time.  Increasing jump range by some set amount over time would be blatantly artificial, as opposed to having 2 or 3 events at random intervals which make small or modest increases, or one major improvement.

For instance, rather than 1 LY per decade, have an event which boosts range by 2LY, then 20-30 years later, a second discovery adds another 3 LYs.  50 years pass before the next improvement, adding a mere 1 LY in range.  The older Jumpships won't necessarily be able to use all of the improvements, so some will only be adaptable to the 3 LY increase, but not the 1 or the 2.  That complicates matters, because now some ships jump 30 LY, some 33, and some 36.

As an alternative, a single new discovery in the field might add 5-10 LY to the range, but only new ships built more than a year or two past that date would have the cores properly shaped for it.  Ships already under construction most likely wouldn't be scrapped and rebuilt.

Col Toda

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Re: Safe superjump?
« Reply #32 on: 22 August 2019, 19:34:43 »
The Lucretia was a jump ship that could jump 120 Light years at a time with a small chance of damage to the KF system . Writen in Conspiracys of the Jihad I think . The faction kept such a tight security lid on it that when the ship and associated labs on it was lost so was the tech . If it was done once it can be done again .

The_Caveman

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Re: Safe superjump?
« Reply #33 on: 23 August 2019, 01:11:56 »
The Lucretia was a jump ship that could jump 120 Light years at a time with a small chance of damage to the KF system . Writen in Conspiracys of the Jihad I think . The faction kept such a tight security lid on it that when the ship and associated labs on it was lost so was the tech . If it was done once it can be done again .

Assuming the story was true. Canon rumor is a thing.
Half the fun of BattleTech is the mental gymnastics required to scientifically rationalize design choices made decades ago entirely based on the Rule of Cool.

The other half is a first-turn AC/2 shot TAC to your gyro that causes your Atlas to fall and smash its own cockpit... wait, I said fun didn't I?

Retry

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Re: Safe superjump?
« Reply #34 on: 23 August 2019, 12:57:10 »
I found this note on the Lucretia in the Sarna wiki.

Although the main source on the Lucretia is the Jihad Conspiracies: Interstellar Players 2 sourcebook, the information pertaining to this vessel is presented as fact, largely found in the Gamemaster/Behind the Scenes sections, and not as a mere canon rumor.

Talen5000

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Re: Safe superjump?
« Reply #35 on: 23 August 2019, 14:07:15 »
I found this note on the Lucretia in the Sarna wiki.

Although the main source on the Lucretia is the Jihad Conspiracies: Interstellar Players 2 sourcebook, the information pertaining to this vessel is presented as fact, largely found in the Gamemaster/Behind the Scenes sections, and not as a mere canon rumor.

Which, given the nature of the book, is not saying much. That "facts" section also speaks of wild rumours and theories and apparentlies.

Given what we know of HPG and KF tech, then the likeliest story is that the Lucretia...if it existed...was a normal Jumpship or an SL prototype that IU found

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Sir Chaos

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Re: Safe superjump?
« Reply #36 on: 31 August 2019, 12:35:40 »
Would it theoretically be possible to put multiple LF batteries on a jumpship?

The ability to do 4 jumps of 30 LY each should be even more useful than that to do 1 jump of 120 LY.
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dgorsman

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Re: Safe superjump?
« Reply #37 on: 31 August 2019, 15:10:13 »
That's kind of the idea with a DropShip mounted battery system.  Jump, switch over to the next battery ship, and jump again.  Pick up a pre-charged battery ship and drop off the expended one.  Kind of an enhanced command circuit,  without the extra JumpShips.

There would be a delay of a day or so between jumps in this case, not necessarily from switching but to avoid stress on the jump core and cooling system.  Doing multiple sequential jumps (even with an LF system) risks damage.
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Sir Chaos

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Re: Safe superjump?
« Reply #38 on: 31 August 2019, 16:46:35 »
That's kind of the idea with a DropShip mounted battery system.  Jump, switch over to the next battery ship, and jump again.  Pick up a pre-charged battery ship and drop off the expended one.  Kind of an enhanced command circuit,  without the extra JumpShips.

There would be a delay of a day or so between jumps in this case, not necessarily from switching but to avoid stress on the jump core and cooling system.  Doing multiple sequential jumps (even with an LF system) risks damage.

You´d still need charged dropships waiting in each system; that´s an improvement over a command circuit, but not by all that much - for example it would not help you pass through an enemy system.
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Liam's Ghost

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Re: Safe superjump?
« Reply #39 on: 31 August 2019, 17:23:36 »
The mass of an LF battery is based on the mass of the jumpship. If you could mount them on dropships to function as an external battery, you'd still need a whole bunch of different ships with different batteries to accommodate the wide variety of jumpships out there, and hope you've got enough of the right type of ships in place where you need them to get any benefit.

Would it theoretically be possible to put multiple LF batteries on a jumpship?

It's never been explained why, but canonically you can't put more than one LF battery on a jumpship.
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dgorsman

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Re: Safe superjump?
« Reply #40 on: 31 August 2019, 18:16:08 »
For the battery ship, I would suggest that the weight would be standardized, or maybe a small/heavy paradigm, to get away from the percentage factor.

And yes, it doesn't help that much for travelling through hostile territory if you intend to pick up extras along the way.  But consider a Star Lord with three transports, and three battery ships.  That's potentially 4 jumps in as many days.

Not *quite* the same as a super jump which gets you there in a single jump, bypassing everything.  And not the same as an integral LF drive which can pull off a second jump seconds after the first.
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Ogra_Chief

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Re: Safe superjump?
« Reply #41 on: 01 September 2019, 01:04:59 »
For the battery ship, I would suggest that the weight would be standardized, or maybe a small/heavy paradigm, to get away from the percentage factor.

And yes, it doesn't help that much for travelling through hostile territory if you intend to pick up extras along the way.  But consider a Star Lord with three transports, and three battery ships.  That's potentially 4 jumps in as many days.

Not *quite* the same as a super jump which gets you there in a single jump, bypassing everything.  And not the same as an integral LF drive which can pull off a second jump seconds after the first.

This may be a dumb question, but presumably the 'battery dropship' would need to charge and recharge. So, would the recharging be done via its' own solar sail or recharge station? Or, by other means?

Also, wouldn't the carrying of a battery ship limit the systems use to emergency personnel transport rather than cargo? Similar to a locomotive carrying extra coal cars, rather than simply refilling coal at the next major yard. Seems impractical from a logistics standpoint.

Or, am I off...
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dgorsman

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Re: Safe superjump?
« Reply #42 on: 01 September 2019, 11:55:04 »
Hadn't gotten around to that part yet.  Given the circumstances, using recharge stations would seem the best.  Including a sail would be interesting, but I'm not sure about space.  And they're not exactly intended for independent operation.  Maybe allowing them to charge off a JumpShip's reactor, same as an integral LF battery, perhaps.

If all collars are used for battery ships then yes, there isn't room for DropShips carrying anything else.  Certainly an option for some command circuits.  In the previous example of the Star Lord JumpShip, there's a mix of each for extended operations - sometimes you just need to get there in a hurry, and screw the inconvenience.  Another option for operating in more friendly space is to keep one collar reserved for exchanging with a charged one after each jump.
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Daryk

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Re: Safe superjump?
« Reply #43 on: 01 September 2019, 12:06:36 »
Being that the "Energy Storage Batteries" that Space Stations use for this exact purpose (TacOps, pages 406-407) weigh 100,000 tons, I can't see how you can justify installing them on DropShips.

dgorsman

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Re: Safe superjump?
« Reply #44 on: 01 September 2019, 12:43:57 »
Uhmmm, what?   ???

You can't mount them on JumpShips for jump drive use at all.  And even then, it wouldn't improve recharge times for subsequent jumps.  Not the system I'm referring to.
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idea weenie

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Re: Safe superjump?
« Reply #45 on: 01 September 2019, 14:02:31 »
For the Li-F battery Dropships, you might go with just using them on giant Dropships, and accept that 25,000 tons of your cargo space is going to be taken up by the battery so it can handle any size FTL ship.  You then have to factor in the the KF cost multiplier for a KF core for a 2.5 megaton Compact Core vessel now being applied with the Dropship cost multiplier.  You might just throw your hands up and decide 5,000 tons is all you need, so it can fit any size Jumpship, and the smaller Warships (1/5 the mass/cost, plus 20,000 tons smaller).  They can be recharged by a Recharge station, or by a Jumpship's solar sail if it is in-system longer than it needs to recharge its own KF core.

Advantage: The cargo can get to its destination much faster
Disadvantage: Expensive!


For the Energy Storage batteries normally mounted on Space Stations, you might go with making half-size batteries that are 50,000 tons each, and needing 2 Dropships to recharge a KF core in deep space.  The Dropships are charged at a Recharge station, saving fuel costs.  Mounting them on a Compact Core Warship takes up at least 4* the mass of a Li-F Battery, but does not have any KF cost multipliers.

Advantage: Much cheaper, and they can recharge the Jumpship simply by parking near the solar sail, or connecting a long extension cord to the ship's power grid.  No need for actually docking the Dropship, meaning they don't take up a Docking Collar
Disadvantage: Need 2 of them per Jumpship, and it takes ~150 hours (the recharge rate for using a Recharge station).  On a Warship it takes up far more room than a Li-F Battery, reducing tonnage available for armor, weapons, sensors, fuel, supplies, etc.

monbvol

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Re: Safe superjump?
« Reply #46 on: 01 September 2019, 14:04:22 »
The mass of an LF battery is based on the mass of the jumpship. If you could mount them on dropships to function as an external battery, you'd still need a whole bunch of different ships with different batteries to accommodate the wide variety of jumpships out there, and hope you've got enough of the right type of ships in place where you need them to get any benefit.

It's never been explained why, but canonically you can't put more than one LF battery on a jumpship.

Well there is a potential practical limitation of mass to explain that for actual jumpships.

Talen5000

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Re: Safe superjump?
« Reply #47 on: 01 September 2019, 15:18:53 »
Being that the "Energy Storage Batteries" that Space Stations use for this exact purpose (TacOps, pages 406-407) weigh 100,000 tons, I can't see how you can justify installing them on DropShips.

Because 100,000 Tons is vastly vastly vastly too much mass to devote to batteries which shouldn't exist.
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Daryk

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Re: Safe superjump?
« Reply #48 on: 01 September 2019, 15:46:31 »
Then perhaps this discussion should make its way down to Fan Rules...

idea weenie

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Re: Safe superjump?
« Reply #49 on: 02 September 2019, 05:19:22 »
Because 100,000 Tons is vastly vastly vastly too much mass to devote to batteries which shouldn't exist.

I figured that the Energy Storage Batteries also contained coolant, allowing the KF core to be charged faster since it is being actively cooled not just by its own coolant grid, but also the coolant contained in the tonnage allocated to the Energy Batteries.

So to me the full 100,000 tons contains:
Coolant storage
Coolant equipment (to bring the stored temperature down low enough)
A steady cooling system so you don't get thermal shock in the KF core from incoming coolant not being the right temperature (it'd be annoying if the incoming coolant caused the helium to vaporize)
A giant extension cord to connect to the receiving ship
Oh, and batteries

Talen5000

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Re: Safe superjump?
« Reply #50 on: 02 September 2019, 07:00:05 »
I figured that the Energy Storage Batteries also contained coolant, allowing the KF core to be charged faster since it is being actively cooled not just by its own coolant grid, but also the coolant contained in the tonnage allocated to the Energy Batteries.

The energy needed to spark a jump is about 130 MWh

A modern 3MW diesel generator masses about 70 tons plus fuel. All it has to do is shine a light on the sail or send a small amount of current through a cable.

Even allowing for mounting, bracing, specialist transmission gear etc....100,000 Tons? There is very little reason JumpShips don't carry these generators themselves.

You just don't get a lot of solar power at a Jumppoint
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Daryk

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Re: Safe superjump?
« Reply #51 on: 02 September 2019, 07:10:03 »
That's all?  I would have figured at least a few TJ, not less than half of one.

Talen5000

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Re: Safe superjump?
« Reply #52 on: 02 September 2019, 09:27:03 »
That's all?  I would have figured at least a few TJ, not less than half of one.

One week of Solar output at a standard Jump point....we know the energy out of the sun and the distances involved. Even if you magnify everything by a couple of orders of magnitude to account for 100% conversion and any vagaries in conversion or mistakes, 100,000 Tons for an energy battery is dubious. Space would have been a better constraint of this sort (not much of one for a station but still better), but the end result is that FASA wanted the solar sail look and that limits the amount of energy a jump requires to the amount that sail can capture. Even if you think up some esoteric reason why you can't spark a jump from an onboard generator - all you need to do is tie that generator to a few lightbulbs and point them at the sail.

You want a few TJ to open a jump point? You can't use a solar sail collecting solar energy for a week. Three or four months, maybe...but not a week

But - FASAfiziks
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Daryk

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Re: Safe superjump?
« Reply #53 on: 02 September 2019, 09:29:49 »
What sail diameter did you assume?

Talen5000

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Re: Safe superjump?
« Reply #54 on: 02 September 2019, 12:53:57 »
What sail diameter did you assume?

1 kilometre, without the cutout
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Daryk

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Re: Safe superjump?
« Reply #55 on: 02 September 2019, 13:18:28 »
Going with a 2km sail would definitely get you in the TJ range without too much trouble.

Col Toda

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Re: Safe superjump?
« Reply #56 on: 02 September 2019, 19:46:38 »
All the improved  jump tech works on both the engines the LF batteries  . Given a choice I would rather have a normal 30 LY jumpship with an LF battery  to have  the  jump back out ASAP option .

A normal jump ship w/o an LF battery and a super jump ship that does 120 LY by consuming  the energy of reengineered LF battery  still loses the as fast as possible  option  .

Talen5000

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Re: Safe superjump?
« Reply #57 on: 02 September 2019, 20:59:02 »
Going with a 2km sail would definitely get you in the TJ range without too much trouble.

The original jumpsails were 50km in size...just much less efficient.

But there is little point in moving to a larger sail as the way BT drives operate, you can't charge a core faster than is already done. A larger sail adds mass, but not much else....you could charge from further away from the star being the only advantage.  Even the McKennas is only 1500m or so.

None of which really changes the point. Which is that the amount of power necessary to spark a jump is very low. Low enough that over a week, simple diesel generators could produce enough power, several times over. You could even argue a trickle feed from the ships existing reactor systems would provide enough power.

Of course, this means sails aren't necessary, but there are certain advantages. And it means energy batteries in stations are largely a waste, especially with the rules that neuter quick charging.
 
 
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Daryk

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Re: Safe superjump?
« Reply #58 on: 02 September 2019, 21:00:34 »
The amount of hydrogen "burned" to charge a drive would give a wildly different number.

Liam's Ghost

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Re: Safe superjump?
« Reply #59 on: 02 September 2019, 21:52:25 »
The amount of hydrogen "burned" to charge a drive would give a wildly different number.

Indeed. The real problem isn't that energy storage batteries are too big or diesel generators should be able to charge a jump drive easily, it's that the whole thing doesn't make sense.

Focusing on just one part of the nonsense doesn't fix the problem because of all the other nonsense. A solar sail of this size at this distance may only realistically be getting this much power, but you still need to burn multiple burn days worth of reaction mass to charge the drive without it. Energy storage batteries are a hundred thousand tons and can only store power which has to be trickle charged across, while the largest possible lithium fusion battery is twenty five thousand tons and can power the core directly, but for some reason you can only have one. Also reaction mass is magic.

None of it fits together well, because it was all bolted together over a couple decades by people who didn't really think too hard about it, on top of prior work by people who thought even less about it. The whole space thing is a mess.
Good news is the lab boys say the symptoms of asbestos poisoning show an immediate latency of 44.6 years. So if you're thirty or over you're laughing. Worst case scenario you miss out on a few rounds of canasta, plus you've forwarded the cause of science by three centuries. I punch those numbers into my calculator, it makes a happy face.

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