jump power

[Hilary_155]

Jump Drive: In order to use the jump drive, the ship
requires a number of Power points equal to 10% of the
hull’s total tonnage multiplied by the maximum jump
number the drive is capable of. Note that this power
requirement is only needed when the ship actually initiates
a jump – at all other times, the jump drive remains inert.

How long is 'initiates a jump'?

Is this one round?
Is this every round of the engineer jump check?

In short, if using high efficiency batteries to initiate the jump, how many are needed?

 

[Condottiere]

1. It's only initiated once, and going by power expenditure, six minutes or less.

2. [power expenditure divided by forty (technological level ten) or sixty(technological level twelve)] tonnes

 

[AnotherDilbert]

Is this one round?

Yes, it is generally assumed, but not exactly defined in the rules.

In short, if using high efficiency batteries to initiate the jump, how many are needed?

E.g. A TL-12 ship of 100 Dton with Jump-2 drive:
Required power: 100 × 10% × 2 = 20 Power.

At TL-12 High Efficiency Batteries hold 60 Power per Dton, so 20/60 = 1/3 Dton batteries are required.

You still need fuel in addition to the power requirement, of course.



Note that you don't have to accelerate the same turn as you jump, so you can use the power that the M-drive would normally use for the Jump drive instead. You can even divert some basic ships power to the jump drive, I call that jump dimming.

 

[whartung]

The duration of the jump sequence is spectacularly undefined throughout the rule sets.

None of the tactical games define it, for example.

I've never seen anything in LBB or TNE. Dunno is MT defined something, maybe the Starship Operators Manual has something.

 

[Condottiere]

I believe prior to the current edition, the presumption was that there was a constant energy requirement, which was how the lanthanum grid functioned.

And presumably the jump net.

 

[AnotherDilbert]

The duration of the jump sequence is spectacularly undefined throughout the rule sets.

LBB5:

Jumping: A ship which breaks off by jumping must have a destination and enough fuel to get there. It must expend energy points equal to two turns output from a power plant whose number is equal to the jump being attempted (EP required = 0.01MJn). If it can do this in two turns, it jumps at the end of two turns. If it can do this in one turn or less, it jumps at the end of one turn (in the pursuit step). A ship which cannot summon the required energy in two turns may not jump at all.

MT has a detailed jump task sequence in Imperial Encyclopedia, p92 "STARSHIP OPERATING PROCEDURES".

It has always been well defined, as far as I can see.

 

[AnotherDilbert]

I believe prior to the current edition, the presumption was that there was a constant energy requirement, which was how the lanthanum grid functioned.

In LBB2'79, MT, TNE, and T4 the jump drive had no power requirement, and nothing to do with the power plant.

I have never assumed the jump drive needs large amounts of power during jump.

 

[Condottiere]

1. Did anyone ever turn off the power plant during the transition?

2. While the jump bubble slowly dissolves over the next week, what keeps the lanthanum grid going?

 

[mike wightman]

There is no lanthanum grid in most Traveller editions - lanthanum is used in the jump coils according to the MWM jumpspace article and CT library data. The network of cables that maintain the jump field is not materially defined in the article and appears to be a DGPism...

 

[aramis]

There is no lanthanum grid in most Traveller editions - lanthanum is used in the jump coils according to the MWM jumpspace article and CT library data. The network of cables that maintain the jump field is not materially defined in the article and appears to be a DGPism...

Better check Supp 11 there, Mike.

Specifically the tug. They just extrapolated from it.

 

[Condottiere]

I don't know about previous editions, but the current one might be deliberately vague, so interpretation becomes somewhat necessary.

The previous editions might have such things implied, in this particular instance, in that no one switches off the power plant.

 

[mike wightman]

Better check Supp 11 there, Mike.

Why? There is no mention of lanthanum in S:11. S:8 has this to say:

Lanthanum: A rare earth element, the first of the inner transition metals. Vital
to the construction of the inner coils of interstellar jump drive units.

Do you mean S:9 Fighting Ships?

Specifically the tug. They just extrapolated from it.

The tug mentions extending the jump field via cables, just like MWM's jumpspace articles mentions a cable network within the hull - the material the cables are made from are not defined in either case. Lanthanum is used to make the jump coils within the jump drive as mentioned in the quote above.

Special field cables attached to the rear of the ship extend the ship's jump field to
include this additional cargo

 

[Grav_Moped]

I don't know about previous editions, but the current one might be deliberately vague, so interpretation becomes somewhat necessary.

The previous editions might have such things implied, in this particular instance, in that no one switches off the power plant.

This gets interesting in the context of a ship design I did a while back that caught a bit of flak from some quarters: LBB2 '81, Jump-6/1G in 400Td at TL 13 using Size M drives (MD-B). Power plant fuel was the issue, mostly due to the inconsistent but high (for small ships) LBB2 fuel requirements.

I realize MgT is a different rule set, but this strongly implies that while you need a Pn-6 power plant to do a Jump-6, you only need it to run at Pn-6 for the 40 minutes (2 HG combat turns) immediately prior to Jump. It takes 5 HG turns to power up (per JTAS #14) from Pn-1 to -6, stays at Pn-6 for an additional turn, then spends the same amount of time winding back down. During this 200-minute period (3 hrs 20 min), it's operating at an average Pn of 4. For the remainder of the week in Jump, it's operating at Pn-1. And in this ship, it's running at Pn-1 the rest of the time as well, since it only has a 1G maneuver drive. Ok, it might need to spike to Pn-3 in combat to run the maneuver drive and the computer's full ECM capability and maybe a couple of lasers -- Mod/6 takes 5EP. Still, that's only several hours at the most during a two-week Jump cycle.

When does it burn the rest of the power plant allocation? CT High Guard tells us that maneuver fuel use is "inconsequential".

But this does give us the MgT XBoat (jumps on battery power but somehow uses its Jump fuel allocation). And that gets interesting if you minimize the post-Jump role of computers -- that is, posit that everything about a Jump is determined beforehand, and once a ship enters Jump Space it's simply coasting to the destination. Do you need a powerplant of Pn=Jn if the batteries for the Jump Drive are charged from an external source, or will one that just covers life support suffice? Does the computer that calculates the course and controls the Jump Drive need to be on the ship? Can you use a tender-ship to provide the fuel in lieu of drop tanks?

The extreme case of this is a Jump-6 ship with just a Jump-6 drive and a token power plant and fuel. No bridge, no crew -- maybe a Mod/1 computer. It's not autonomous and doesn't need to be. It's basically the jump equivalent of a recoilless rifle round fired from a gun with a really good targeting system. (The analogy isn't to a ballistic rocket since those carry their own fuel rather than expending it immediately when fired.)

Ignore the 100Td minimum for Jump and Jump Torpedoes are back...

 

[whartung]

LBB5:


MT has a detailed jump task sequence in Imperial Encyclopedia, p92 "STARSHIP OPERATING PROCEDURES".

It has always been well defined, as far as I can see.

So, then. How long does it take?

When the captain says "Jump us out of here Scotty! NOW!"

What does Scotty say? "I've got to have XXX minutes, Cap'n!"

An interesting note about the HG sequence is apparently the capacitors can't hold a charge very long, thus the 40m (2 rounds, 20m per round, right?) time limit.

How does MT address that?

 

[AnotherDilbert]

So, then. How long does it take?

It's MT. There are several tasks, each with a time increment, then you roll and modify that or something. I can't be bothered...

If you don't like MT, use the time frame from HG as a minimum time for an emergency jump?

An interesting note about the HG sequence is apparently the capacitors can't hold a charge very long, thus the 40m (2 rounds, 20m per round, right?) time limit.

I have no idea what they are saying with that. I guess it is not so much about the capacitors, as another way of saying you have to have a PP-N to make a Jump-N, you can't cheat and use a small PP and charge the capacitors for a longer time.

When used for Black Globes there is no limit to how long they can hold a charge.

How does MT address that?

It doesn't; MT works like LBB2'77: The jump drive has nothing to do with the power plant. The jump drive includes a fusion reactor that burns the jump fuel.

 

[Condottiere]

1. I don't think you can have it both ways with (jump) capacitors, the energy charge deteriorates after a set time.

2. The exception might be that this doesn't happen when the black globe is activated.

 

[AnotherDilbert]

1. I don't think you can have it both ways with (jump) capacitors, the energy charge deteriorates after a set time.

2. The exception might be that this doesn't happen when the black globe is activated.

So the charge deteriorates, but it does not deteriorate?

Too complex for me...

 

[whartung]

MT says Jump takes 2 minutes. There's 2 prep tasks (2m each), but they can be done anytime. The actual Jump is a 2m task. Now maybe it takes to minutes to align the dials, unlock the big red JUMP button, and press it, then who knows how long the actual jump process takes.

But, task time, routine 2m task.

Starship Operators Manual addresses the capacitors (but doesn't address jump timing).

It says that the capacitors are these zuchai crystals that have two distinct properties.

1) They not only store the energy, but they deliver the energy the way it was charged. So, for a contrived example, if you charged with with 5 volts for 1 minute and then upped it to 10 volts for another minute, when you discharge it, it discharges at 5v for 1 minute, and 10v for the other minute. This is a nice mechanic that eliminates something like a solar array powering jump, can't get the charge in fast enough.

2) The crystals decay after 2-3 hours of holding a charge and can spontaneously explode. This means that you charge it, but you can't hold it for very long. But, by the same notion, it's certainly long enough to charge the capacitors, and disengage from, say, drop tanks or even a fuel shuttle.

It seems the point of the capacitors is to ensure you have the entirety of the energy budget vs perhaps risking a power plant failure during the transition.

It also claims the power plant is within the jump drive.

HG claims all of the jump drives have capacitors, but, strangely, the amount of capacitors they come with isn't enough to power the drive.

HG says you need 0.01MJn EP to jump, but the capacitors in the drive only supply 0.005MJn.

I find the 2m number from MT to be unreasonable. Consider a 100KdTon ship with Jump 4. That's 40KdTons of fuel "consumed" in 2m? 560K m3 of fuel. That's over twice the rate of water flow over Niagara Falls. That's just...a lot. Real fast.

AFAICT Gurps Traveller does not address jump time. TNE does not address jump time. Mayday, Brilliant Lances, and Battle Rider -- the tactical games, where you think it might be important to be able to jump out under fire, do not address jump time.

Does T5 address it?

Even the Starship Operators Manual does not address jump time.

For something so well defined, they all sure do a lousy job of defining it.

 

[AnotherDilbert]

MT says Jump takes 2 minutes. There's 2 prep tasks (2m each), but they can be done anytime. The actual Jump is a 2m task. Now maybe it takes to minutes to align the dials, unlock the big red JUMP button, and press it, then who knows how long the actual jump process takes.

But, task time, routine 2m task.

The given time is a time increment. Actual task time is longer:

HOW LONG DOES THIS TASK TAKE?
The time increment on a task profile is 10 percent of the typical task duration. A roll of 3 dice (whose average result is 10) determines how many increments the task takes. The increment is always one-tenth of the typical task duration.
If the duration of the task doesn’t matter, the task is Instant and that’s that. No time roll is made.
If the duration always takes the same time, the task is Absolute. No time roll is made.
The duration of an attempt equals the increment times 3D (after any DMs are applied). The minimum is 3 increments.

Note that default time is ( 3D - task DMs ) × increment, hence it is not trivial to calculate an average time. A better trained or educated engineer will, on average, complete the task faster.

Hasty or Cautious can also change the duration.

 

[AnotherDilbert]

HG says you need 0.01MJn EP to jump, but the capacitors in the drive only supply 0.005MJn.

Plus whatever energy you get from the jump fuel, i.e. a lot more...