MGT Fuel

[Solomani666]

Actually, no, not canon in the sense that a week in jump is canon; not since 1992. TNE and T4 use kL per year... and not much even then. They are canon, so canon is in a dual state... and Gareth picked the less sensible choice of the two, presumably out of ignorance of the other option and its closer relationship to reality.

Keep in mind... doing a little back of the envelope calculation, a single liter of mixed duterium & tritium (in the ratio 2D to 4T) is 8442467 MJ of recoverable energy (ignorign Neutron energy, thus accounting for the 80% loss to the neutron; if you can recover the neutrons, multiply that by 5); at 250 MW, 33769.868 seconds per liter, or 9.3 hours per liter, or 70L per 28days... Assuming a whoppingly bad 1% efficiency, 7kl per 28 days per 1Td drive... half a ton fuel per ton of drive per month is about as much fuel as can be credibly swallowed.

Your best fusion drives, presuming they have the same rates of power out as MT/TNE peak, are 1/4th as efficient, or 0.25% recovery.

Oh, and using the "cool it with hydrogen" doesn't fly, either; the energy you can pump in it is pretty darned low before it energetically finds its way out of confinement...

And as maneuver fuel? you're far better off with much denser materials for reaction mass. water is 14x as dense, and more easily magnetized... and mercury is another 9x that and much easier to accellerate... smaller tank, smaller tank mass. Heck, Amonia and Methane are better for reaction mass than LHyd.

It's one of those issues that resulted in MT and T4 explicitly using reactionless thrusters for the 3I.

In any case, however, accepting a 3000+ year old and 6 TL old technology as being in the 1% efficiency range is a stretch. It's reasonable to expect at TL9 a 1% efficiency (by assuming a 90% capture of energy and 90% overhead cost), but not TL15. Heck, current issues are that the current peak efficiency is about -20%, due to energy capture losses, from what I last read... that is, the recoverable energy is 80% of the overhead of causing fusion.

Now, the other thing is that about TL12, fusion should get a MAJOR energy boost, since neutron energy should be recapturable, given the introduction of damper tech, and other TL12-15 advances (and thus cutting fuel use by up to a factor of 5).

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Now let's start this over again with the (highly inefficient) 4H reactors found in most Imperial starships and not the (optimal) tritium deuterium reactors you speak of...

...then account for unrefined fuel in some cases...

...a powerplant that sacrifices efficiency for durability, reliability, and ease of mantenance...

...Due to above reasons the power plant may be simply be either on or off...

...Shields but does not recollect neutron energy due to the extra cost, maintenance and mass...

...Provides an unspcified amount of power to grav plates, acceleration dampeners, thrusters and weapons...

...Uses a large portion of it's fuel as coollant for both the power plant and the ship in general...

...Uses hydrogen to create a warp bubble around the ship, and cool it, while in jumpspace...

The very nature of the Imperium dictates that any advances in technology take literally HUNDREDS OF YEARS to become commonplace.

I ame sure that somewher in Core there are the efficient, cutting edge, powerplants in ships that you speak of, and the infistructure to support them, but it will be several hundreds of years before most 'travellers' see them in the Spinward Marches.

 

[captainjack]

Quote right, just had a chat to Charlotte about this.

The new system is that enquiries go straight to her. However, they _must_ be addressed to her email and they _must_ have the S&P submission enquiry in the subject header, or they run a very real risk of getting missed.

Charlotte goes through these mails twice a week and responds to them all - so, if you have not heard anything within a week, something has gone wrong. Drop her another line.

One submission, well before Christmas, (I think, possibly before Thanksgiving ) several weeks and an email later, comes the answer:"we're busy and haven't gotten to it yet ". Fair enough. Then: Three to four lines dropped, three or so months , no response, nothing, not even "no thank you".

So what now, Matt ?

 

[Solomani666]

I find it amusing that we (RPGers) are so quick to accept that fusion will generate several orders of magnitude more power at several orders of magnitude less cost, but are shocked that efficiency should not be comparable to an internal combustion engine.

What is the efficiency of a modern fusion reactor?
Last I heard, the goal was still 'break-even'.

How much energy does a high pressure magnetic confinement bottle require?
Last I heard it was enough to make many question whether it could ever be a viable rocket nozzle.

Even at 0.1% efficiency, the Traveller Fusion reactor would still be a cheaper way to generate power than a fuel cell or fission.


As an aside, most theoretical research on reactionless propulsion suggest that it would be unimaginably power intensive (like generating black holes power intensive). This suggests that all of the handwavium (reactionless thrusters, grav plates, inertial compensation) will require every bit of power that can be extracted from that hydrogen. Think iron as the exhaust.


With respect to 'multiple reactors', I agree that ships should have multiple reactors. However, I also feel that initiating a multi-megawatt output controlled fission reaction using simple hydrogen and generating negligible radiation or waste heat should require more time than 'turn the key and start her up' - like an automobile engine. IMTU I like an hour startup.

So if you intend to save fuel by shutting down the weapon's fusion power plant, don't expect to ge able to maneuver and shoot at the same time for less than an hour.

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FYI Fusion power does exist today and actually works:
Google Video: Bussard Fusion
(A boron11 and hydrogen reaction actually results in 'no extra neutrons' hence no radiation after the reactor is turned off!)
It is the ONLY combination in the periodic table that does not result in lingering radiation. (3 x He4 is the byproduct)

Remember that in the Traveller universe, pure (sometimes tainted) hydrogen is used in fusion reactors aka 4H reactors. (4 hydrogen atoms are fused into 1helium atom.) This is a VERY innefficient way of producing a fusion reaction compared to fusing say tritium and deuterium and does not yield the same power output, but the fuel is usually free.

 

[Jame]

I submitted my retcon to S&P; they published it in Signs and Portents issue 76. (A link will come in, eventually.) If you wish, read it and see what you think.

 

[Mithras]

I think its a great 'retcon' I've adopted it wholesale.

Thanks Jame!

 

[Solomani666]

I submitted my retcon to S&P; they published it in Signs and Portents issue 76. (A link will come in, eventually.) If you wish, read it and see what you think.

Excellent!

I will be using those rules for a sublight ship I need to design and for satellights and base stations.

For simplicity sake when designing regular ships I simply replace the word "week" with the word "month".

 

[cryingblackoil]

Silliest...argument...ever.

Arguing over how much power an, as yet, non-workable science would make and multiple, as yet, non-existent sciences require.

I can't believe I read this whole thread. Either take the rules and use them or spend the time make up your own. o:

 

[aramis]

Silliest...argument...ever.

Arguing over how much power an, as yet, non-workable science would make and multiple, as yet, non-existent sciences require.

I can't believe I read this whole thread. Either take the rules and use them or spend the time make up your own. o:

Fusion is VERY MUCH real science. It's being done daily by several labs... at a net energy loss. We know how much energy is released per reaction, and how many reactions that can be sustained per unit mass of fusibles...

the fuel use rates in Traveller are comparable to tactical nuclear weapon rates... So we need an explanation why that much energy isn't vaporizing the engines. And where the rest of it is going.

 

[atpollard]

Fusion is VERY MUCH real science. It's being done daily by several labs... at a net energy loss. We know how much energy is released per reaction, and how many reactions that can be sustained per unit mass of fusibles...

the fuel use rates in Traveller are comparable to tactical nuclear weapon rates... So we need an explanation why that much energy isn't vaporizing the engines. And where the rest of it is going.

Traveller achieves 0.001% fusion efficiency (99.999% of the energy goes back into maintaining the magic bubble that can withstand the temperatures and pressures).

 

[aramis]

Traveller achieves 0.001% fusion efficiency (99.999% of the energy goes back into maintaining the magic bubble that can withstand the temperatures and pressures).

At which point, most of the surface area should be radiators... the energy HAS to go elsewhere... it's part of the laws of thermodynamics...

Traveller PP fuel rates only make sense in story-mode, not in any kind of realism mode.

 

[far-trader]

Traveller achieves 0.001% fusion efficiency...

At which point, most of the surface area should be radiators... the energy HAS to go elsewhere... it's part of the laws of thermodynamics...

Traveller PP fuel rates only make sense in story-mode, not in any kind of realism mode.

IF...

...all the fuel is burned in a fusion reaction. If a substantial part of it is used for other purposes (and imo it has to be), such as dumped coolant or reaction mass, it's a little more palatable. Yes, other media may be better for that but it makes more sense than presuming it is all used for incredibly inefficient and massive power production which is then wasted.

 

[aramis]

IF...

...all the fuel is burned in a fusion reaction. If a substantial part of it is used for other purposes (and imo it has to be), such as dumped coolant or reaction mass, it's a little more palatable. Yes, other media may be better for that but it makes more sense than presuming it is all used for incredibly inefficient and massive power production which is then wasted.

I suspect instead, it's like 90% efficient at TL15, but uses only the deuterium and tritium, and has a 50% return cost.... the rest is simply dumped overboard... because the energy carried off by the remainder of the fuel is trivial compared to the fusion energy release even burning the only 0.01% non-protium...

At which point, the radiators are reasonable (still need to be pretty large, but not most of the hull)...

 

[atpollard]

it's part of the laws of thermodynamics...

Never heard of it.
... Must be related to Conservation of Momentum, Speed of Light and other mythical concepts.

... WE have Gravitics. Thats real.

 

[cryingblackoil]

Fusion is VERY MUCH real science. It's being done daily by several labs... at a net energy loss. We know how much energy is released per reaction, and how many reactions that can be sustained per unit mass of fusibles...

the fuel use rates in Traveller are comparable to tactical nuclear weapon rates... So we need an explanation why that much energy isn't vaporizing the engines. And where the rest of it is going.

Right on, man. Exciting stuff, but that is exactly what I said. As yet unworkable=fusion. As yet nonexistent=Gravitic manipulation. And since fusion is currently in it's infancy while we know how much energy is released in a theoretical 100% efficient reaction (barring new scientific principles that sidestep or change our understanding much in the same manner hyperspace or jump would sidestep Einstein without contradicting him), we have no idea how much a workable reactor will produce.

And the second part too. As to where the "rest" of it is going, no one knows how much it takes. MgT, in a smart move IMHO, didn't put wattage outputs on the power plants, nor wattage requirements on the drives, laser, unknown life-support techs....pretty much anything (unlike other editions, as I understand secondhand). That leaves no ammunition for argument, right? Because you neither know how much energy anything is producing or consuming.

 

[aramis]

Right on, man. Exciting stuff, but that is exactly what I said. As yet unworkable=fusion. As yet nonexistent=Gravitic manipulation. And since fusion is currently in it's infancy while we know how much energy is released in a theoretical 100% efficient reaction (barring new scientific principles that sidestep or change our understanding much in the same manner hyperspace or jump would sidestep Einstein without contradicting him), we have no idea how much a workable reactor will produce.

And the second part too. As to where the "rest" of it is going, no one knows how much it takes. MgT, in a smart move IMHO, didn't put wattage outputs on the power plants, nor wattage requirements on the drives, laser, unknown life-support techs....pretty much anything (unlike other editions, as I understand secondhand). That leaves no ammunition for argument, right? Because you neither know how much energy anything is producing or consuming.

Wrong.

We know how much fuel is used, and there is canon that it's Protium fusion... so we know how much heat is generated. Even if not collected, ALL that heat has to escape. Either as work, or as radiation. Further, any on-board work ends up as heat in same magnitude. Thermodynamics again.

Since we know that it's using X fuel, and X fuel releases Y energy, ALL that energy needs be accounted for.

 

[cryingblackoil]

We know how much fuel is used, and there is canon that it's Protium fusion... so we know how much heat is generated. Even if not collected, ALL that heat has to escape. Either as work, or as radiation. Further, any on-board work ends up as heat in same magnitude. Thermodynamics again.

Since we know that it's using X fuel, and X fuel releases Y energy, ALL that energy needs be accounted for.

Hey, saw the post first let me say Happy Birthday to ya.

Ok, I agree with almost everything you just said, just not the conclusion.

I think we are agreed on how much fuel is used. Likewise, conservation of energy (again, barring now scientific principles). I also agree with your recap as long as X=Y gets a -W on the end like you pointed out in the paragraph above.

So now that we are agreed on the basics let me tell you how you where my problem is and why I have to disagree with you. Let me come at it through your words, you said X=Y-W, right? Alrightly, you said you know the value of X and Y. So simple math would tell you that the difference is W.. the amount of work done e.g. Gravitics, which as I pointed out you *don't* know so can't say that it is wrong. At least without it being a kneejerk reaction.

 

[cryingblackoil]

IF...

...all the fuel is burned in a fusion reaction. If a substantial part of it is used for other purposes (and imo it has to be), such as dumped coolant or reaction mass, it's a little more palatable. Yes, other media may be better for that but it makes more sense than presuming it is all used for incredibly inefficient and massive power production which is then wasted.

Good point, but can we can rule out incredibly inefficient and massive wasted power production if the standard fuel can be obtained free? I don't think so. I mean...heck, I'd jump at three miles per gallon over forty-five if the fuel was obtainable for free, right? And anyone who disagrees with that I accept check, cash, or money orders to help you get rid of that extra money. =P

 

[far-trader]

Good point, but can we can rule out incredibly inefficient and massive wasted power production if the standard fuel can be obtained free?

Even if it was free I'd take efficiency over having to tow a huge tanker trailer or stop every (EDIT) 50 miles to fill the onboard tank

 

[BytePro]

But not if it was 2 weeks - right?

Most folks I know would gladly fill-up everyday and lose their trunk space for 'free' fuel... YMMV, but wouldn't say you'd be in the majority.

Won't even talk about the waste heat and inefficiencies of vehicles - markets have very little to do with how efficient things are - heck, we are still pumping electrons for data processing and communications because of politics and cable TV.

Gravitics - as a pure fictional, fantasy aspect - has always been the perfect place to dump (pun) a thermal solution, IMTU. I've always kept units abstract - using 'Power Units' (EPs in CT) instead of RW units. Saves stretching another set of suspenders of disbelief...

 

[aramis]

Hey, saw the post first let me say Happy Birthday to ya.

Ok, I agree with almost everything you just said, just not the conclusion.

I think we are agreed on how much fuel is used. Likewise, conservation of energy (again, barring now scientific principles). I also agree with your recap as long as X=Y gets a -W on the end like you pointed out in the paragraph above.

So now that we are agreed on the basics let me tell you how you where my problem is and why I have to disagree with you. Let me come at it through your words, you said X=Y-W, right? Alrightly, you said you know the value of X and Y. So simple math would tell you that the difference is W.. the amount of work done e.g. Gravitics, which as I pointed out you *don't* know so can't say that it is wrong. At least without it being a kneejerk reaction.

Except that you're ignoring that the ship has to eliminate X power in waste heat. All work ends up as waste heat. Thermodynamics again.
And we know how much of the gravitic drive's energy is converted into off ship work (basic physics, but non-linear). Whatever isn't converted directly into work is waste heat.

So, you're arguing X!=X.