PP Fuel requirements

[DFW]

Another nonsensical item in star ship design rules I couldn't find an answer to in the books:

Example; a 200t ship with J2 & M1 requires PP model B. Makes sense so far as you need the added power to use the Model B J-drive. However, when not using the J-drive why are you burning PP fuel at double the rate of a J1, M1 200t starship? What are you doing with the added power output? Continually
firing your energy weapons?

 

[rust]

Continually firing your energy weapons?

No, according to Imperial law once you leave jump space you have to turn
on all the christmas tree lights on the ship's hull and to announce your car-
go manifest on all communication channels in order to make it easier for
the pirates to find your ship.
Otherwise the pirates would find no prey and would go out of business,
the Imperial Navy would have its budget cut because there are no more
pirates to hunt, and then the Emperor would be not amused because
his beloved navy would have to shrink. :shock:

I have no doubt that the Emperor's peace of mind is worth a little power
wastage. 8)

On the other hand, it could have been introduced to avoid the separate
fuel use calculation for each jump ...

 

[hdan]

Another nonsensical item in star ship design rules I couldn't find an answer to in the books:

Example; a 200t ship with J2 & M1 requires PP model B. Makes sense so far as you need the added power to use the Model B J-drive. However, when not using the J-drive why are you burning PP fuel at double the rate of a J1, M1 200t starship? What are you doing with the added power output? Continually
firing your energy weapons?

Yeah, that's a head-scratcher. To make matters worse, in other Traveller incarnations, the Jump Fuel actually pays for the PP's overdrive to fire the JD!

The way I see it, a Class B power plant takes a certain amount of fuel to keep the fusion "fire burning", which somehow has very little to do with how much power the plant is providing at any one instant.

It does make sense that you should be able to dial back the PP's output to match your requirements, but to really model that, we'd need some idea of what the rest of the ship requires in terms of "power points", which as we all know is kind of a hot button topic.

And let's not even get started on Maneuver Drives.

The real answer of course is that the rules are meant to be simple - you need to refill the ship every X weeks, the "standard usage" assumes you're running your M-Drive most of the time you're in a system, etc. As a GM you should allow your players to reduce the PP fuel consumption if they choose to "power down non-essential items" or some such.

 

[DFW]

... On the other hand, it could have been introduced to avoid the separate fuel use calculation for each jump ...

:lol:

But, it doesn't effect the amount of fuel used for jump. Only during non-jump. The easy fix is to make weekly fuel usage (not including what you use for Jump which you account for separately anyway) equal to that used by a PP model that is minimum needed for the M-Drive size.

 

[rust]

The easy fix is to make weekly fuel usage (not including what you use for Jump which you account for separately anyway) equal to that used by a PP model that is minimum needed for the M-Drive size.

In my settings I use the fuel requirements of a fusion reactor type A for
all ships in normal space and add the higher fuel requirements only when
a ship moves through jump space.

Edit.:
Sorry, bad wording. What I mean is that in my settings a ship at rest only
uses the fuel required by a type A reactor, while moving through normal
space it uses the fuel required by its maneuver drive type, and while mo-
ving through jump space it requires the fuel for the jump number.

 

[phavoc]

Keep in mind that Mongoose "tweeked" jump drive activity. It USED to be that you pumped power into your jump grid and once it had enough stored it would activate the jump drive. Jump drives used a "grid" of sorts to generate a field around the ship while it existed in jump space.

Now Mongoose says that most of your jump drive fuel is pumped out into space around your ship to create a jump bubble universe, and that bubble slowly collapses over the duration of your trip until it gets too small and then you revert to normal space - hopefully at the destination of your choosing.

I agree that this is one of many oversights in the rules that has existed for a very long time. Generally speaking your power requirements are going to be extremely small while in jumpspace since you only need to power lifesupport and the relatively miniscule power draws the users of the ship will make charging their 3d ipods or playing on the tri-d.

 

[DFW]

Thanks guys. I think I'll go simple and use PP fuel requirements pre week that equal the MDrive code.

 

[atpollard]

Another nonsensical item in star ship design rules I couldn't find an answer to in the books:

Example; a 200t ship with J2 & M1 requires PP model B. Makes sense so far as you need the added power to use the Model B J-drive. However, when not using the J-drive why are you burning PP fuel at double the rate of a J1, M1 200t starship? What are you doing with the added power output? Continually
firing your energy weapons?

First Thought ... If I idle a 10,000 HP diesel engine (zero output to the drive shaft) would it consume no more fuel than a 10 HP engine also at idle (zero output to the drive shaft). [It would consume more fuel at idle.] Then why should a larger Fusion PP not have a higher base fuel consumption?

Second Thought ... since real Fusion Reactors have yet to reach 'break even' and the fuel consumption is massive for the energy produced, perhaps 90% of the fuel/energy output is required to sustain the fusion reaction (like in the magnetic bottle).

Third Thought ... What is the power consumption of negating inertia and generating an artificial gravity (to avoid being plastered to the aft wall during acceleration)? Perhaps the 'magic' technology that is so conveniently ignored is power hungry.

 

[DFW]

First Thought ... If I idle a 10,000 HP diesel engine (zero output to the drive shaft) would it consume no more fuel than a 10 HP engine also at idle (zero output to the drive shaft). [It would consume more fuel at idle.] Then why should a larger Fusion PP not have a higher base fuel consumption?

Interesting but they aren't really analogous mechanisms.

Second Thought ... since real Fusion Reactors have yet to reach 'break even' and the fuel consumption is massive for the energy produced, perhaps 90% of the fuel/energy output is required to sustain the fusion reaction (like in the magnetic bottle).

Yes, but that doesn't address the variable "throttle" which MGT PP's have per the rules.

Third Thought ... What is the power consumption of negating inertia and generating an artificial gravity (to avoid being plastered to the aft wall during acceleration)? Perhaps the 'magic' technology that is so conveniently ignored is power hungry.

It is the same as for a ship the same size without a J-Drive in operation. Hence, the reason I brought up the subject in the 1st place.

 

[rinku]

Effective rating should also consider M-Drive use. And the minimum rating will be the minimum size plant viable for that hull, not an A drive. Big ships have bigger overheads.

Also, it's clear that a big J-Drive DOES still require a big plant, however the jump fuel is being used, even if that peak usage is only at jump (though maybe it needs to run during that week in J-space?). Rule is there.

I'd call it that if the ship neither used its J-Drive or M-Drive at a higher rating in the 2 week cycle, it can use a lower PP fuel use appropriate to the actual use.

(If the ship were in mothball and only using enough power to allow routine maintenance, running it as an A drive makes sense, but not if it's being used).

 

[rust]

(If the ship were in mothball and only using enough power to allow routine maintenance, running it as an A drive makes sense, but not if it's being used).

I think that the power output that is sufficient to accelerate a 200 dton
ship with 1 G while all other ship systems (sensors, communicators, etc.)
are active should be sufficient to run all systems except the drive on at
least all "player character size" ships while they are in orbit, at a starport
or otherwise "at rest".

 

[Vargr]

Just ignore power plant fuel and covert the tonnage into extra cargo space.

What is the autonomy of a ship? Years...the real limitation is not fuel, or power, but life support consumables (2-12 months stateroom/person).

 

[rust]

Just ignore power plant fuel and covert the tonnage into extra cargo space.

This is how GURPS Traveller does it, there a new fusion power plant co-
mes with enough internal fuel for 200 years, so the need for power plant
fuel is extremely rare.

While I am very much tempted to use this for my setting's starships, it
does not fit in as well with the setting's other fusion power systems, so I
continue to use starship reactor fuel, although at a very low level.

As for life support, GURPS Traveller uses closed total life support systems
on the higher technology levels. What they produce is barely edible, but
sufficient to survive, and a ship could operate for many years without ha-
ving to introduce additional life support materials.

 

[rinku]

Another take (which verges on a house rule) is that the PP fuel usage isn't so much the fusion reaction itself but reaction mass. The process might be effectively converting spare hydrogen into gravitons or quarks or whatever, which are then propelled away from the ship producing some kind of thrust. So, maybe 1% of the fuel requirement is going toward electrical power, 10% is being used for the hydrogen->graviton conversion and thrust and the remaining 89% is unconverted reaction mass. Or other numbers plucked out of the air.

Yeah, I guess if the ship isn't using any drives or weapons then you can pretty much ignore fuel use. The life support/maintenance costs would cover that. (i.e. fuel IS being used in this situation, but not enough to bother keeping track of).

 

[Captain Jonah]

I use the rated fuel requirement when using the larger drive and a lower requirement when using a lower drive.

For example J3, M1, P3. For the week in jump powering the jump grid you need to be burning fuel at the full rate to maintain power 3. Once you emerge back into normal space and use the M1 drive you need only Power 1. For stand by you would most likely need enough fuel to run the powerplant at the 1 levelas you need to maintain the fusion reaction which requires a level of fuel and power just to keep running.

MonT uses fuel H for the jump bubble but you still need to energise the jump grid which is what the power plant energy is constantly for. MonT doesn't mention the jump grid much but it is a solid part of the cannon minefield

As an aside a ships power plant doesn't use Hydrogen anyway, a fusion plant is either Deuterium + Deuterium (D+D) or Deuterium + Tritium (D+T). You can get D from refining the H you scoop at a gas giant or river, it exists naturaly where ever you find Hydrogen but in very small volumes (0.015%)ish. One Dton of Hydrogen scooped from a gas giant will produce 0.15 litres of Deuterium.

A 200 ton ship with J2 and M1 needs a P2 for the jump drive, this gives 4dtons of fuel per 2 weeks for the power plant at max (2dtons per week of jump) and 2dtons per 2 weeks at Power 1 (1dton per week) for manover and standby. But what is it using for fuel. Hydrogen has one proton, trying to create fusion with just Hydrogen would be something to watch (from a safe distance). The same ship (Far Trader) has 44 Dtons of fuel which could produce several litres of Deuterium for the fusion plant and all the remainder when the rubbish is cleared out is H for the jump bubble.

More of this on the Metalic Hydrogen thread.

 

[DFW]

I use the rated fuel requirement when using the larger drive and a lower requirement when using a lower drive.

For example J3, M1, P3. For the week in jump powering the jump grid you need to be burning fuel at the full rate to maintain power 3.

From what I've read in th MGT rules, there is no grid powering while in Jump space. The H bubble maintains the pocket universe not a grid maintaining the pocket.

 

[Captain Jonah]

So what is the jump drive being powered to do when in jump?

Main rule book says:

Jump travel is the only known means by which a vessel may travel faster than the speed of light. To Jump, a ship creates a bubble of hyperspace by means of injecting high-energy exotic particles into an artificial singularity. The singularity is driven out of our universe, creating a tiny parallel universe which is then blown up like a balloon by injecting hydrogen into it. The Jump bubble is folded around the ship, carrying it into the little pocket universe.
This new universe is short-lived, and will eventually collapse,
precipitating the ship back into normal space several light-years
from its original position.

So the jump drive creates a black hole and forces high energy exotic particles (hic) into it creating both a rift in space time into which the ship falls and a bubble universe which hangs around for a week.

This throws itself headlong into the cannon minefield and rolls around as well

Aside from the whole pocket universe thing which is a grandfather trick it also goes against years and years and years of Jumpspace being an area you travel through not a pocket you create. Quantum theory can handle the idea of jumping through higher or lower quantum dimension where though you maintain the constants of your own space you move under the constants of the dimension you are in such as Distance Traveled equals Time x Speed not being what it is in our dimension, hence travelling light years in a week without going FTL with mass.

How exactly is this intended to work in theory, using a massive gravity source to twist or fold space time is fine but leads more towards portals/stargates/wormholes. How do you get out of this pocket universe before it collapses in on itself taking you with it. Do you need to actively jump to get out of it? If you are blowing up a pocket universe that is totaly cut off from the rest of the universe and this is all the fuel is used for why do you need to refine it, any gaseous mass will do the job if its just to blow up a ballon.

Lots of cannon, lots of adventures written, lots of established details from previous versions. I like the simple MonT rules overall but some of the MonT science I tend not to use and go with what has come into being over the many years I have been playing.

Besides I love the graphic idea of the jump grid both powering up going into a jump and the flare as a ship emerges from jump and bleeds of the excess energy. Some of the great pictures of Traveller have been of this effect

 

[rust]

I like the simple MonT rules overall but some of the MonT science I tend not to use and go with what has come into being over the many years I have been playing.

My way out of this mess of blowing up singularities and thelike is the hy-
perdrive, it does away with the entire "jump science" as well as the fuel
requirements, and as a nice side effect it allows for small ships with more
useful interior volume. :wink:

 

[DFW]

Besides I love the graphic idea of the jump grid both powering up going into a jump and the flare as a ship emerges from jump and bleeds of the excess energy. Some of the great pictures of Traveller have been of this effect

I quite agree.

 

[phavoc]

Bottom line is, I personally think, MGT screwed the pooch with their "revisioning" of jump travel. They took something that worked, made sense (so to speak), and had lots of established background information and came up with their version.

It's certainly not any better, and raises more issues without closing any loopholes that the original version came with. I'm not sure how they take hydrogen and change it into "exotic particles"... And it used to be you wanted pure hydrogen for power generation, now you need it for power and as material to open up a pocket universe. So if you have unrefined fuel, would you now have an unrefined universe?

Hmm, now that I think about it, I do believe the Argo was using MGT jump drives at the very beginning of its journey from Earth to Iscandar. Having unrefined fuel and a corrupted pocket universe would have definitely explained the odd things they saw in their first jump... dinosaurs and the like.

Yep, I think I get it now.

PS - For the uninitiated, that's humor from Star Blazers...