How do jump drives really work?

[shadowcat20]

Ok, I have been reading a lot of differing opinions on this board lately about Jump drive operations.

How do they really work?

First I will give you my ideas on it then toss back some of yours. I only have T1 and T20 to go off of so those with the other versions may have information I do not.

Known- A Jump drive uses large amounts of fuel all at once to perform the Jump.

Known- A drive has capacitors needed for the process but they can not store a small fraction of the power generated by burning all that fuel.

Known- Jump capacitors can be recharged by the power plant or Black Globes.

Known- Large amounts of power are needed to start the jump process.


This leads me to reason that in the Jump process the capacitors use their charge to open the jump point. This process empties the units in a quick burst of energy. After the point is open the fuel will be burned to continue charging the jump point while the ship enters it. Most of the fuel will be used in the process of entering the jump point. The ship will exit when all the energy is spent from the process.

I have seen some people hint that like Battletech only capacitors are needed for the process. This idea has 2 flaws.

First what is to keep a high tech fleet from jumping in in 2 ranks. The first rank Globes then the second rank fires at them till their caps are almost charged. If you hit the center of the Rear of the ship the globe will screen the effects and energy from the opposing side. Then flip ranks and repeat. This makes no sense as the amount on energy needed to recharge them would be much less then burning fuel.

Second, just running your power plant until the caps are charged would burn less fuel then the Jump drive. Why have Jump drives at all with huge amounts of fuel tankage when you could carry 3 or 4 jumps worth of spare capacitors for a lot less space. Just recharge them at starports or larger ships.

So no, Capacitors should not be all that is needed to make a jump. They just are needed to jump start the Jump Point.

What are your guys takes on this? What am I missing?

 

[aramis]

Ignoring T5 for the moment

You charge the capacitors...
...and THEN the fuel is burned... somehow... using that energy from the capacitors, and that from the fuel...

You rip a portal open into JSpace...
and you sling yourself into J-Space on a parabolic course, which always exits you about a week later (in some reference frame) and usually within about 3000km of the targeted point.

 

[far-trader]

Ignoring T5 for the moment

You charge the capacitors...
...and THEN the fuel is burned... somehow... using that energy from the capacitors, and that from the fuel...

Hunh?

Oh, right. High Guard and the silly Black Globe charge the jump drive but still need the fuel idiocy. Correct? (forgive me if the term "idiocy" insults anyone, it's my opinion)

Never made any sense to me.

IMO, you burn the fuel, all of it(1) in one big fast semi-controlled fusion flare, the energy of which both charges the capacitors(2) (in a very precise and measured manner) and rips a tear into one of six known jump space dimensions. You then tumble into the tear in a very precise manner governed by the capacitor discharge (no jump grid, no jump bubble) and after a precise, predetermined time you emerge at a precise, predetermined point in space. Unless you screw up and misjump of course...

(1) in original CT that meant the full jump drive rating, not just the distance covered, then there were (briefly) jump governors to save fuel, before all jump drives used only the fuel needed for the distance (though always a full parsec even if the distance was marginally more or less)

(2) I'm not even sure I like capacitors in the mix, but if I want BGs I kind of have to swallow capacitors too, and I'm not sure I don't want BGs, though dumping them would fix a few issues

 

[Dragoner]

To me I use the idea of a "jump" is to actually create a quantum tunnel (ie wormhole) then create a quantum bubble around the ship and proceed through the tunnel, as the tunnel collapses behind the ship. The week interval is a failsafe to prevent the ship from reaching the speed of light in the process and thereby atomic time stops, freezing the ship in a "forever null" like a pocket universe. So in some ways the jump drive is like a dual phase projector/capacitor circuit.

 

[whartung]

JTAS 24 has an article by some Marc guy about jump.

It mentions the requirements for jump:

Power Source. He cites Fusion (fast), but also Solar (slow) and Anti-matter (magic).
Energy Storage Nodes. Capacitors or batteries.
Strong Hull. Starship hulls have integral wiring "which maintains the jump field around the ship".
Computer. To calculate the jump.
Jump Coils. Made of lanthanum, used to "control the drive energies during jump".

A "typical jump" consists of calculating the coordinates, then a rapid, inefficient (i.e. some fuel is wasted in the process and some used for cooling) energy charge of the the capacitors (this process takes "less than a few minutes"), and finally the capacitors feed the jump drive.

From this article I gather that jump is done SOLEY from the capacitors, and the bulk of the fuel is consumed in the "inefficient, rapid charging process", then the capacitors are fired.

Citing solar as a possible energy source tells me that the capacitor charge time is not relevant (since you can use capacitors or batteries). Rather the premise is that if you DON'T use the inefficient, fast energy generation process, the jump will simply take too long to perform. As in "too long for convenience", not is any way preventing the jump. Its simply more convenient and standard operating procedure to flash consume vast amounts of fuel to perform the jump in minutes than to use the slow charging method. Mind, there's no indication of how much energy a jump power plant creates, or how much is necessary for jump, or how long the "slow way" would take. The closest we have for that is the EP usage in HG, and those EPs, as I recall, are pretty low all things considered.

I would assert that since the "nominal" flight time for an interstellar journey is the time from take off from the high or downport to 100D, then however long the "slow way" takes to charge a jump capacitor, it's longer (by some large margin) than it takes to get to 100D. Simply, the cost of the fuel and tankage via SOP, etc. is less than the TIME lost sitting around waiting for a jump capacitor to charge the "slow way", and that's why "it's just not done".

So, take that all for whatever it's worth to you. Fuel for the flames.

 

[shadowcat20]

All good replys and points of view. Keep it going.

Edit: Makes one wonder though, if caps are all that is needed why do Xboats not just have caps and no fuel? They are one shot anyway. That would be 40 more tons of cargo or a power plant so they could jump again after recharging themselves. Jumping on Caps alone it is WAY too easy to break the system. There HAS to be a something else to avoid serious misuse of capacitors.

 

[Xerxeskingofking]

as i understand it, one reason cited (i think it was Mega Traveller) for the "fast" build up was the nature of the capacitors used for the jump. they were built to charge/discharge very, very fast in a regular manner, as variations in the power flow when jumping caused misjumps. A side effect of building the capacitors to dump all thier power in one go was that they were not very good at holding the charge stablely for long periods of time, so they had to flash charge it just before use.

 

[mike wightman]

cough - Annic Nova - cough

Doesn't use hydrogen at all for its jump drive.

 

[shadowcat20]

Ok, Annic Nova is one I do not have.


But after reading JTAS 24 again I noticed the term Cooling. Maybe the Jump is done by caps alone. But the heat buildup is so great that large amounts of LHyd are needed to keep things from melting down. So...You could charge and jump without fuel but would come out the other end as a heated slush. That would explan Misjumps a bit. impurities in the fuel would disrupt the cooling process and safetys would kick in and drop you out of Jumpspace. Or the drive would fail and drop you out. This would be the random factor of where you ended up.

 

[aramis]

cough - Annic Nova - cough

Doesn't use hydrogen at all for its jump drive.

Just means it's a TL 22+ drive... (MT Ref's Manual shows decreasing fuel rates for TL 17-21... TL<16=x5, 17=x4, 18=x3, 19=x2, 20=x1, 21=x0.5)

 

[rancke]

cough - Annic Nova - cough

Doesn't use hydrogen at all for its jump drive.

Of course it does. It's just that the hydrogen is supplied by the Ancient device that connects to a pocket universe filled with hydrogen that the Annic Nova is built around. [NB: My own idea; not canon].


Hans

 

[whartung]

Ok, Annic Nova is one I do not have.
But after reading JTAS 24 again I noticed the term Cooling. Maybe the Jump is done by caps alone. But the heat buildup is so great that large amounts of LHyd are needed to keep things from melting down. So...You could charge and jump without fuel but would come out the other end as a heated slush.

Then that detail would make Drop Tank impossible (to wit I reference the 10 billion message thread over that-a-way --->). The premise of the drop tank is that the fuel in consumed in its entirety prior to jump.

Mind this does not eliminate your cooling point, but whatever cooling there may be needs to happen prior to jump.

 

[shadowcat20]

Drop tanks would still be good if the cooling was done BEFORE the jump. The whole process is quickly done just before the leap. If there was not enough cooling (Impurities) then things would not go off as planned.

Good point though. That means if you jumped without fuel the engine would slag down before entering J-Space.

This is why I started this thread, to clear things up for me and others. Some of the drop tank comments were starting to reach out there a bit.

 

[mike wightman]

Actually the coolant idea ties in nicely with the annic nova's hydrogen less alternative jump drive.

The very slow capacitor charge from the solar collector does away with the need for coolant, but it takes a week or more just to charge your drive.

And no - the annic nova is not an ancients ship or a TL22+ ship.

(the Imperium let you keep it for a Cr100,000 salvage fee and the ship is valued at MCr200 - ancient or very high TL artifacts would be impounded and studied, not sold off.
The original JTAS article also gives other instances for using this ship type)

 

[rancke]

The problem with the coolant idea is that hydrogen is far from being the most efficient substance for that purpose. You could save a considerable amount of volume by using just the amount of hydrogen you need for the fusion and, say, oxygen for the coolant. (There are more efficient substances than oxygen too, but this way you can store the materials for a second jump as water).


Hans

 

[aramis]

perhaps all or almost all that fuel is, instead of burned, compressed to a damper suppressed high-density plasma (It's roughly 10:1 compression) and then bolted out to rip open space through some kind of structure.... but that doesn't tie to damper tech well.

 

[mike wightman]

Very, very hot oxygen will react very badly with anything it comes into contact with.

 

[mike wightman]

perhaps all or almost all that fuel is, instead of burned, compressed to a damper suppressed high-density plasma (It's roughly 10:1 compression) and then bolted out to rip open space through some kind of structure.... but that doesn't tie to damper tech well.

Except annic nova shows you don't need any fuel at all for a jump drive to work.

 

[Ronnke]

I can't quote my reference, or even if it is just a figment of my imagination... But my understanding is that the hydrogen fuel is used to maintain the bubble around the ship while it is in JSpace. Something to the effect that JSpace is like a balloon and the hydrogen keeps it inflated and stops it collapsing on the ships hull. Which is bad.

This is why all the hydrogen is consumed regardless of the distance jumped and the amount of fuel you need is governed by the size of the ship.

EDIT:

So the process would be:

1. Ship uses power plant or capacitors to create a breach into JSpace.
2. The ship enters JSpace and "inflates" the bubble around the ship.
3. JSpace then collapses onto a protective cushion of hydrogen which surrounds the ship until the ship emerges again in normal space.

Drop tanks are thus valid in this case.

Also the JDrive and "wiring" in the ships hull in interacts with the hydrogen around the ship in a way that maintains the jump field. Using impure hydrogen makes maintaining that field more unstable and strong sources of gravity can make field maintenance impossible. Gravity is a force that penetrates the all known levels of JSpace equally.

 

[shadowcat20]

The Hydrogen Bubble was mentioned on another thread on this site. Can not remember which one though.

It is interesting trying to fit together tidbits of tech from many years of writings from different people. I thought I had it until Marc's article in JTAS 24....

Keep the ideas coming.

We have to find a way to open the Jump point on caps, and find a use for fuel after the fact but before the ship enters said space. Hmmm...maybe the LHyd is used as reaction mass to enter the Jump Point because other types of thrust would disrupt the opening. the larger the jump the more umph needed.