Newbie question - Jump travel and fuel consumption.

[Jeff Hopper]

I'm talking heat engine conversion efficiencies, which is probably the source of confusion.

Even really simple heat engines have efficiencies in the double digits.
What you are probably refering to is the matter-to-energy-conversion. 0.0something% for modern nuclear fisson seems the right order of magnitude.

You're right. It is the matter to energy to usable energy conversion. I'm dipping from a knowledge well that is almost 20 years old and I'm sloshing terms all over the place...

 

[Jeff Hopper]

Who says that Traveller Fusion reactors need to a Thermal loop to take power off of the reaction?

I was giving a possible explanantion for the excess fuel use.

Cool. Just looking for base assumptions, a lot of

If there is another way you use in YTU to convert the thermal energy of the fusing hydrogen to electrical power, then I'm all ears. The fusion plants in MTU use MHD turbines and heat exchangers in steps on a loop of the plasma but it still isn't 100% efficient.

There a couple of ideas out the about using the electron flux from the chamber as the power take-off. Which might be just playing around with ideas, but I tend to run a solid state sorta universe so I try to keep my techno-babble within that for at least the internals of things like Power plants.

As a side question for the general populace, is fusion power the densest power source in your universe? Or do other high energy sources exist?

That is what the MHD turbines do in MTU, they tap off of a side plasma loop of the fusion plant for the electrical power take-off and the cooling system from the MHD turbines helps to power a secondary electrical grid using thermocouples and heat exchangers.

As far as power goes in MTU, there is fusion, antimatter assisted fusion, antimatter, and the really fringe stuff like zero point energy and harnessing quantum black holes or quantum singularities.

For world industrial applications, there is a battle between solar power satellites and fusion plants using better fuels (like Helium3 - Deuterium).

 

[AKAramis]

I'm no engineer, but 5% efficiency is really crappy isn't it? If you convert the energy directly to electricity (using some kind of really beefy solar-panel type thing that directly absorbs photons or whatever from the fusion reaction) then you should be able to get much higher efficiencies than that, even with our current level of technology on Earth.

The waste heat is a whole other can of worms though - Traveller ships don't have the required heat sinks/radiators, and most people just armwave it as being dumped into jump space or something (which doesn't really explain it either).

The best current fusion (that I've read about) runs at -10% efficiency before capture; that is, produced power is 10% less than power to trigger fusion, not counting the fact that current panels peak at around 25% (http://www.treehugger.com/files/2006/10/sunpowers_new_s.php says 22%)

This means net efficiency of current fusion is -81%!!!

In order to make fusion feasible, we need a net efficiency of 450% of the cost of fusion. If we can achieve that with massive fuel bypass, hey, no problem.

We know the absolute energy release; what we don't know is how much will be working at the time. We can estimate some 30-50% energy capture within reason... but since we don't know what will have to be done, we can only make SWAGs at what the costs of fusion will be.

It's possible that the costs of fusion are massive, say 99% of the captured energy... in which case, 100x the fuel rate is perfectly reasonable, and given the relative cheapness of the fuel, that's likely to still be economically viable.

 

[anari]

Howdy all,
So what is the answer in the OTU of Mongoose? Does the Jump Fuel include the fuel needed to power the ship, or do you still burn 1 weeks worth of Fusion Power Plant fuel?


Thanks,


Anari

 

[Reynard]

"Ships in Traveller use the same fuel - hydrogen - to power both the Jump drive and the power plant..."

"A single Jump of that distance consumes that much fuel."

"The fuel amounts listed will power the ship for two weeks..."

All there in black and white.

 

[sideranautae]

I was giving a possible explanantion for the excess fuel use. If there is another way you use in YTU to convert the thermal energy of the fusing hydrogen to electrical power, then I'm all ears.

I don't don't use "hot" fusion. IMTU it is P-P fusion with quantum tunneling. Alpha, beta & gamma voltaics. Capture of neutrons for secondary ionizing radiation & 99% of the Lhyd is coolant for the Thermoelectric generators. (no other way to account for the insane amount of "fuel" used.

Done

p.s. superconductors brings the distribution loss down to insignificant ranges.

 

[sideranautae]

Howdy all,
So what is the answer in the OTU of Mongoose? Does the Jump Fuel include the fuel needed to power the ship, or do you still burn 1 weeks worth of Fusion Power Plant fuel?

The jump fuel is not used to supply the PP, per the rules. Fuel consumption rules for the PP state what fuel is used. It would have to state the Jump fuel IS used by the PP, otherwise it isn't.

 

[sideranautae]

That being the case, the only reason you'd use hydrogen in large amounts over very short timescales must be because the Jump Drive itself requires it (to create and maintain the jump bubble for example).

Naw, the logical reason is that most of the PP fuel is used as a coolant.

 

[GypsyComet]

Howdy all,
So what is the answer in the OTU of Mongoose? Does the Jump Fuel include the fuel needed to power the ship, or do you still burn 1 weeks worth of Fusion Power Plant fuel?

The jump fuel is not used to supply the PP, per the rules. Fuel consumption rules for the PP state what fuel is used. It would have to state the Jump fuel IS used by the PP, otherwise it isn't.

Canon descriptions of older Vilani drives and the required connection between Jump drive and PP rating (in several but not all editions) do suggest that the Power Plant is being used as part of jump initiation, and that the jump drive is just the field generator, etc. What all that fuel volume is being used for specifically during jump initiation, whether it be sheer power (meaning ships could be incandescent briefly), coolant, or jump field inflation, or some combination of those, is a technical detail that we have only inferences for.

All we know for certain is that the tanks are full and become (mostly) empty, and a jump is started.

 

[sideranautae]

Canon descriptions of older Vilani drives and the required connection between Jump drive and PP rating (in several but not all editions) do suggest that the Power Plant is being used as part of jump initiation,

I'm only commenting on MGT. In MGT Trav the Jump fuel is used exclusively for creating a hydrogen bubble. PP fuel usage is calculated 100% without reference or in conjunction with JD or JD fuel usage. In other words, the rate of PP fuel usage doesn't vary with JD use.

 

[Reynard]

If we're going to cite canon from older editions then I shall add The Starship Operator's Handbook: "A special high-yield fusion power plant *incorporated within* the jump drive itself provides the energy. The jump drive power plant consumes copious quantities of fuel very quickly in order to charge the energy sinks (typically zuchai crystals) with high-grade energy in preparation for the jump transition."

The jump drive has its own power plant and the main plant is separate. One reason they only dim lights out of tradition than necessity. This is MegaTraveller canon but it still details the fluff and is consistent with the jump and power plant descriptors in the Mgt Core book.

 

[GypsyComet]

Canon descriptions of older Vilani drives and the required connection between Jump drive and PP rating (in several but not all editions) do suggest that the Power Plant is being used as part of jump initiation,

I'm only commenting on MGT. In MGT Trav the Jump fuel is used exclusively for creating a hydrogen bubble. PP fuel usage is calculated 100% without reference or in conjunction with JD or JD fuel usage. In other words, the rate of PP fuel usage doesn't vary with JD use.

The ten minutes of high burn through the PP to feed power to the jump drive isn't going to affect the PP's own fuel tankage requirements, true. At least not when the ship design system stops at whole dtons. Significant digits play an important role in both the question and the answers.

If we're going to cite canon from older editions then I shall add The Starship Operator's Handbook: "A special high-yield fusion power plant *incorporated within* the jump drive itself provides the energy. The jump drive power plant consumes copious quantities of fuel very quickly in order to charge the energy sinks (typically zuchai crystals) with high-grade energy in preparation for the jump transition."

The jump drive has its own power plant and the main plant is separate. One reason they only dim lights out of tradition than necessity. This is MegaTraveller canon but it still details the fluff and is consistent with the jump and power plant descriptors in the Mgt Core book.

MegaTraveller also used many other different assumptions in ship handling, while CT and Mongoose track fairly close to each other. One of those changes was treating the jump drive as its own high burn power plant.

Vilani Jump Dimming is only a tradition *now*. For over half of the Vilani history of jump drive use, it was a technological requirement.

 

[sideranautae]

The ten minutes of high burn through the PP to feed power to the jump drive isn't going to affect the PP's own fuel tankage requirements, true. At least not when the ship design system stops at whole dtons. Significant digits play an important role in both the question and the answers.

There is no "ten minutes of high burn through the PP to feed power to the jump drive" in MGT. Just as there is no Fusion PP embedded in the Jump Drive in MGT... I am ONLY answering to MGT's RAW on this as it is a question from a new player.

 

[GypsyComet]

The ten minutes of high burn through the PP to feed power to the jump drive isn't going to affect the PP's own fuel tankage requirements, true. At least not when the ship design system stops at whole dtons. Significant digits play an important role in both the question and the answers.

There is no "ten minutes of high burn through the PP to feed power to the jump drive" in MGT. Just as there is no Fusion PP embedded in the Jump Drive in MGT... I am ONLY answering to MGT's RAW on this as it is a question from a new player.

Then please explain your own rationale for why the power plant rating must match or exceed the jump drive rating. Top of page 107, column 2.

 

[sideranautae]

Then please explain your own rationale for why the power plant rating must match or exceed the jump drive rating. Top of page 107, column 2.

Because it needs to power the JD. Which is NOT the same as an extra high energy output. ANYMORE than saying that a PP has to have ten minutes of high burn to power a weapon that requires a certain PP rating. There is NO rule in MGT stating that a PP's output changes for ANY length of time to power allowed items on the ship. None whatsoever.

YOU can of course make that a house rule in your MGT game. But that is all it would be. A house rule.

 

[GypsyComet]

Then please explain your own rationale for why the power plant rating must match or exceed the jump drive rating. Top of page 107, column 2.

Because it needs to power the JD. Which is NOT the same as an extra high energy output. ANYMORE than saying that a PP has to have ten minutes of high burn to power a weapon that requires a certain PP rating. There is NO rule in MGT stating that a PP's output changes for ANY length of time to power allowed items on the ship. None whatsoever.

YOU can of course make that a house rule in your MGT game. But that is all it would be. A house rule.

You really need to chill out.

The rules do not state that a power spike occurs, but do mention that power plants can strain to provide enough power to the jump drive. The process of power diversion is also sufficiently ticklish that it calls for a skill roll (p.141). If all I needed to do to power the jump drive was feed it normal operations for a minute, a skill roll would be hard to justify. The only inference that makes sense is that the Engineer is asking the power plant to do something unusual and tricky, even at TL15.

I can come up with several reasons why a ship needs more fuel for a longer jump, but one of them is certainly "more power in that 60 seconds". The RAW doesn't speak to that question either.

 

[sideranautae]

The rules do not state that a power spike occurs, but do mention that power plants can strain to provide enough power to the jump drive.

Cool. I never read that rule in MGT. I don't have my books to hand so can't look up where is says that "PP's strain to provide power to the JD".

 

[GypsyComet]

p141, Column 1, "Preparing for Jump"

 

[Reynard]

Yeah, you pointed out again what I've seen the information but gets lost bouncing back and forth through all the rules. One section states the separation of Jump fuel and PP fuel then the other section states it power plant uses the Jump fuel to fire up the Jump engine while not using any more than normal fuel operation of the PP. Sounds like the PP has a supercharging function above normal function. Since it occurs for only less than ten minutes with a week or more between activations, there's no stress on the PP. This holds up when you realize the PP size is dependent on the larger of the drives rather than the size of the jump alone.

Still, jump fuel for a jump and power plant fuel for all other operation before, during and after jumps IF the ship even has a jump drive.

 

[Dracous]

That being the case, the only reason you'd use hydrogen in large amounts over very short timescales must be because the Jump Drive itself requires it (to create and maintain the jump bubble for example).

Naw, the logical reason is that most of the PP fuel is used as a coolant.

Which makes sense really, how else would all that heat be dumped from the ship.