Why is the power plant rating set to the higher of jump or maneuver?

[DangerousThing]

This is something that has bugged me for a long time.

Why is the power plant set to the higher of the M-Drive or the J-Drive?

I can see making the power plant at least equal to the level of the J-Drive, but the maneuver drive uses so little fuel that it isn't even counted.

I also have troubles with a fusion reactor that runs efficiently and the. With little notice can gulp down 10-50% (or more) of the ship size in fuel within 20 minutes...

I've calculated the power used by the T5 systems in EP-Weeks and it rarely takes that much power to use the maneuver drives. Even the jump drives seem to only use a small fraction of the power plant.

I was doing this to figure out how much energy would be needed if the ship was run on near-perfect energy cells. I was thinking of some type of battery that is non-chemical, but stores energy in electron spin or by pushing the electrons closer to the nucleous or somesuch handwavium.

I was led to this thought by various statements that hydrogen is the most common energy source available. Personally I think that electricity itself would be more common. Systems without gas giants or easily available water sources could use giant solar panels close to the sun to charge ships.

Also I rarely allow gas giant skimming because I don't think that it's practical for a starship to do this. I think that you'd need a rather specialized type of ship. Plus, IMTU some really unfriendly sophants live in many gas giants and they have the technology to enforce a no-skim-zone. They occasionally migrate to other gas giants via an unknown FTL system. There is occasional trade for high tech gizmos that they can create for things that we can create in our near vaccum and cold environment.

 

[BytePro]

The reasons are, I'm sure, quite meta-game - bear in mind that Classic started without EP. If you want rationalizations, those are generally left as an exercise for the reader - and that's a very good thing - most authors are not domain experts enough to avoid making their rationalizations even less believable - and worse, 'breaking' the interleaved game balance. Plus, science advances - too many details can easily be overrun by reality.

'...but the maneuver drive uses so little fuel that it isn't even counted.'
That is not accurate - it is factored into the normal fuel requirements. Using the M-Drive requires a rated PP, so in that sense it is different by M-Drive rating, not different by the amount of Gs. If you need a rationale, its rather simple ... the number of Gs capable is an artifact of the design, not of power put in. In other words, a 6G drive pretty much draws the same power regardless of whether 0G or 6Gs are being called for. Keep in mind, Gs are directional as well, at least in CT. This is basically what the rules imply - as is gravitic compensation. If you take the ship as a closed system - the M-Drive, regardless of Gs and ratings, maintains a net +1g within the system ... +6Gs of accel must be compensated out by -5G to interior.

[My TU rationale is based on discrete 'G states' - much like subatomic states - and the drive only operates at one base 'potential' based on design, that may be easily regulated over its operational acceleration range with only negligible power difference above the baseline.]

Fusion physics is a subject of the RW - but breakeven-plus reactors are still make-believe - so the common notion that Traveller reactors are unbelievably 'inefficient' is not actually based on reality at all. Further, no RW power source, in practical use, is even close to the efficiency most laypersons are led to believe based on Science 101...

But on the presumption that Fusion reactors provide a useful hefty energy surplus - gravitics is a handy handwavium dumping ground, IMTU.

Sounds like you have a pretty customized TU/rule set as is - why is this any kind of problem for you? 'I was doing this to figure out how much energy would be needed if the ship was run on near-perfect energy cells.' = make it match the EP needed and you are done, mechanics wise...

If you want a layman-ish rationale - define PP ratings as higher voltage output - therefore matching or exceeding drive ratings in terms of voltage. (Wattage is still higher - meaning more fuel.)

HOPE this gives you somethings to work with - not trying to come off critical or arrogant!

 

[GypsyComet]

This is something that has bugged me for a long time.

Why is the power plant set to the higher of the M-Drive or the J-Drive?

I can see making the power plant at least equal to the level of the J-Drive, but the maneuver drive uses so little fuel that it isn't even counted.

I also have troubles with a fusion reactor that runs efficiently and the. With little notice can gulp down 10-50% (or more) of the ship size in fuel within 20 minutes...

I view the requirement in light of the old bit about the Vilani "tradition" of jump dimming. Back in the early days the jump drive was *just* the jump mechanism, needing power from the power plant to run.

At the same time, the M-Drive and weaponry are the two most power hungry items the rest of the time, and since weapons are used only once in a great while, the M-Drive sets the required power plant rating.

Note that in the editions that don't use a rating system the power plant requirement is is also removed, but replaced by "real world" power units instead (whether the numbers bear any relation to reality or not).

As for that fuel swilling jump drive mode, you can think of a ship about to jump like a car getting on the freeway. A LOT of fuel is required to go from surface streets to freeway speed, even though both are pretty efficient once you are there. Entering Jump space requires immense amounts of power in a short time. In some editions the jump drive includes a hot fusion plant, generating several orders of magnitude more power in twenty minutes than the regular plant generates in a year. In other editions it is assumed the regular power plant has a "jump charge" mode that guzzles fuel. Finally, some editions assume that most of that fuel is *not* consumed, but instead is vented into the jump bubble to "inflate" it so the ship will fit with room to spare. Any of these approaches work just fine but have ramifications that, in most cases, only your Engineer PC will care about.

 

[whartung]

As for that fuel swilling jump drive mode, you can think of a ship about to jump like a car getting on the freeway. A LOT of fuel is required to go from surface streets to freeway speed, even though both are pretty efficient once you are there. Entering Jump space requires immense amounts of power in a short time. In some editions the jump drive includes a hot fusion plant, generating several orders of magnitude more power in twenty minutes than the regular plant generates in a year. In other editions it is assumed the regular power plant has a "jump charge" mode that guzzles fuel. Finally, some editions assume that most of that fuel is *not* consumed, but instead is vented into the jump bubble to "inflate" it so the ship will fit with room to spare. Any of these approaches work just fine but have ramifications that, in most cases, only your Engineer PC will care about.

The curious thing is that in TNE, the Jump Drive is basically self contained and requires NO power. It has no megawatt requirement, just a fuel requirement, so the power plant isn't stressed at all.

 

[GypsyComet]

That would be the first option I mentioned, yes. MT is similar, though the numbers are much higher (being a projection from the Striker approximations with no reality check).

 

[Cryton]

Simple reason is, the PPlant needs to be equal to the drive rating for it to power the drive at full efficiency. If its not, it will lower the drives efficiency to that of the PPlant.

Example: J2, 1G, PP 1, can only do jump 1 until it upgrades its PP rating to 2.

Mind you, this is only true in those editions of Traveller where a PPlant is required to operate a Jump Drive.

~Rich

 

[Vladika]

I was led to this thought by various statements that hydrogen is the most common energy source available. Personally I think that electricity itself would be more common.

Electricity isn't an energy source. It is energy. Hydrogen is an energy source; it is "burned" to create electricity.

Hydrogen is the most common element in the universe.

 

[mike wightman]

In original CT the power plant had to be at least equal to the maneuver drive. You didn't need a power plant for the jump drive - hence the x boat.

In original CT the maneuver rive was implied to be a reaction drive an power plant fuel was used for manoeuvring, then along came HG 1 and the maneuver drive was defined as a fusion rocket.

HG1 did two very silly things though. It got the sizes of the maneuver drives and jump drives switch compared with CT, and it introduced a sentence that the power plant has to be a the same rating as the jump drive or maeuver drive.

HG2 dropped the reference to fusion rockets, maintained the drive switch , and made explicit that you need a power plant for a jump drive - bye bye x-boat .

The EP system implies that energy is require for the manoeuvre drive rather than reaction mass and before long you had the folks at DGP giving us the reactionless thruster hand wave.

 

[DangerousThing]

Electricity isn't an energy source. It is energy. Hydrogen is an energy source; it is "burned" to create electricity.

Hydrogen is the most common element in the universe.

I may not have used the proper terminology, however, I still think that using some sort of batteries/accumulators on ships would be better than carrying H2.

First, hydrogen isn't what is needed on the ship, electricity is.

Second, even systems without a large or economical source of hydrogen can still usually generate electricity.

I do remember the olds days when a jump drive was a specialized fusion plant.

 

[simonh]

I may not have used the proper terminology, however, I still think that using some sort of batteries/accumulators on ships would be better than carrying H2.

First, hydrogen isn't what is needed on the ship, electricity is.

Ok, but that electricity has to be generated somehow. Batteries don't generate electricity, they only store it. Where does it come from? It's hard to imagine any battery technology that can compete with the incredible energy density of hydrogen fusion fuel.

Also nowhere does it say the power produced by power plants has to be converted to electricity before being used in an M Drive or J Drive.

Second, even systems without a large or economical source of hydrogen can still usually generate electricity.

I do remember the olds days when a jump drive was a specialized fusion plant.

There are ways to generate electricity other Than hydrogen fusion, sure, but none of them other than anti matter come close in terms of efficiency.

The idea of jump drives being specialised fusion plants came from DGP and MegaTraveller. I don't have much of a problem with the way DGP went with Traveller technology actually. They felt they needed to pin things down a bit at least for the OTU setting, and bearing in mind every approach has pros and cons I think they did fine.

Simon Hibbs

 

[BytePro]

... It's hard to imagine any battery technology that can compete with the incredible energy density of hydrogen fusion fuel.

Well, electrons are much, much smaller than hydrogen - the trick being to store and use them without the atomic scale overhead.

That said, I prefer my fusion reactors - though Jump capacitors can suffice for a short period.

Also nowhere does it say the power produced by power plants has to be converted to electricity before being used in an M Drive or J Drive.

Yeah, at least with CT this was always my take - that it could very well be in the form of gamma rays and neutrinos, for instance, directly usable by the drives... with Classic HG2, its all just EP.

IMTU, PP output is electricity - supporting all the ship systems and the drives which generate fields and exotic particles themselves. Huge J-Drive fuel requirements being for its own use in creation of a field and continuous over the jump (as opposed to, say, the H-bubble premise of MgT - which requires dumping all the H in very short order into a singularity, IIRC).

 

[Rynak]

Batteries contain a finite charge and even the best capacitors have difficulty completely eliminating all of their charge. Beyond that, what happens when that charge is empty? If you are close enough to the sun, then you can use solar power and you have just reinvented how the majority of our satellites work. Otherwise something needs to recharge those batteries or your ship is now drifting and soon to be lifeless, unless you have enough charge to make it to your destination.

Besides hydrogen to helium conversion (fusion), you also have antimatter reactions which is effectively a very controlled, if not volatile, mass to energy conversion. In any case, energy is converted to heat and not to electricity since neither reaction really effects electron energy (spin) state in a controlled fashion. Our fission power plants use the heat to vaporize water into steam and use that to spin turbines that generate the electricity. This is true for nuclear submarines, some of our smallest and most (known) advanced nuclear reactors. Mass to energy conversion is probably one of the most efficient energy sources, assuming you can create antimatter with little energy loss in the process. Unfortunately until science can come up with something better than steam turbines for electricity generation, there is A LOT of energy currently lost in heat and friction. Not to mention the start up delays with any reactor because the entire system must be brought up to temperature slowly to prevent any issues with the steam lines and turbines.

Now you have the issue of actually moving a ship through space. The easiest way to conceptualize it is through thrusters of some sort. Hot gas is expelled, which propels the ship (and can also shoot through a turbine and generate electricity for the ship as well). More exotic drives exist in science fiction and physics has even proposed some of them may actually work, but may require energy requirements that are too terrible to actually use, at least with our current understanding of the universe. Gravitic drives, warp drives and worm hole creation (such as jump drives and possibly even hyperspace drives, depending on the genre).

Atmospheric scoops on gas giants have been theorized for many decades. The atmosphere should be relatively thin at the altitude needed, but probably incredibly hot, similar to re-entry on Earth. This would be a relatively safe process, if the line up is done right, as you simply have your course utilize gravity to help sling shot you along while obtaining fuel. Hopefully the course helps offset some of the increased drag so fuel can be obtained in a fairly efficient manner. Obviously this only helps for fusion reactors, but could be used in matter-antimatter conversion for the matter portion. Hoped you packed enough anti-matter

The short answer is, there are a lot of ways to skin a cat, er trope. Pick whatever makes sense to you and your group and feel free to run with it. Do a little research if you are trying for a hard science fiction feel, or design your favorite concept into a space opera where hard physics take a middle or more back seat in order for a larger than life story to develop. Have fun and remember that it is your game.

 

[DangerousThing]

Batteries contain a finite charge and even the best capacitors have difficulty completely eliminating all of their charge. Beyond that, what happens when that charge is empty? If you are close enough to the sun, then you can use solar power and you have just reinvented how the majority of our satellites work. Otherwise something needs to recharge those batteries or your ship is now drifting and soon to be lifeless, unless you have enough charge to make it to your destination.

On board ship, everything is a finite resource, even hydrogen.

If ships ran off batteries, then an entire infrastructure would be in place to support this. I'm assuming near perfect superconducting rechargable power cells.

One way to think about a perfect power cell is (analogy ahead) is like a really big unbreakable clockwork winding spring. With the spring, you wind it. The more the spring is wound, the more difficult it is to wind it further.

With a rechargable power cell, the more energy in the cell, the more difficult it is to put in more. The battery on an exploration would be large enough to move the ship though several jumps with basic recharging from a small fission plant.

To simplify the numbers, I used T5 EP. Power cells have capacities in EP-Weeks, at least when used for starships. If I have a 1000 EPW battery, it would take 500 EPW to charge the battery to half way, or 500 EPW. It would take another 500 EPW to charge the battery the next quarter (to 750 EPW). Then another 500 EPW to get it another 1/8th. And to simplify things the remaining 1/8th takes 500 EPW also.

Charging at a starport is fairly inexpensive and faster than doing this by an on-board reactor.

Now you have the issue of actually moving a ship through space. The easiest way to conceptualize it is through thrusters of some sort. Hot gas is expelled, which propels the ship (and can also shoot through a turbine and generate electricity for the ship as well). More exotic drives exist in science fiction and physics has even proposed some of them may actually work, but may require energy requirements that are too terrible to actually use, at least with our current understanding of the universe. Gravitic drives, warp drives and worm hole creation (such as jump drives and possibly even hyperspace drives, depending on the genre).

I use the basic reactionless thrusters that are used by most Traveller games. EP in, thrust out.