How do jump drives really work?

[rancke]

Also the recharge rate of the Annic Nova would be dependant on distance from and size of the star they are recharging off of. In Rift space there would be no close energy sources so charging times would be VERY long.

Unless the ship, unlike the Annic Nova, was designed by someone with enough smarts to include a small fusion power plant and an adequate supply of hydrogen. Then it would be able to jump multiple times between refuelling and without having to worry about being near enough to a star to collect energy from it.


Hans

 

[shadowcat20]

Or fill the hold with spare caps.

This is getting back to where I start ranting about breaking the system...

EDIT: The funny thing is if Mac got on the board and made a decision that would be the end of it....we would go with his comments. In the end it is just a game though.

 

[McPerth]

We also need to accommodate the fact that unrefined fuel can cause misjumps.

The "coolant" theory doesn't really work too well under those circumstances, since would not all Hydrogen isotopes work equally well?

Maybe all hidrogen isotopes could be as useful as coolant, but refining usually means to take impurities off, not to separate isotopes. WHen you skim from a GG, You take hidrogen, but also helium, some traces of amonia and methane, etc.

that avoided the question
What is the canon energy requirements for entering jump space?
in SI units, if you please....

if its unknown or unstated, just say so.

guesstimating based on fuel tankage that would be needed for regular jump doesn't count unless you can state either "All jump fuel is used to produce energy" or "X% of jump fuel is used to produce energy and the rest is used for 'blahblahblah'".

I gave you the calculatios (more or less the same way than shadowcat20's entry before this one) en my entry on Dec 31th (page 4 this same thread).

Althought, you must take into account that power output is calculated in power units (Mw), while energy stored must be calculated in energy units (Mw h or Mj), and to convert the output power to energy you must know what time teh power is applied. As you can see in my previous entry, when MT says that every kl of jump sink may store 650 Mw, I asumed it menat Mw h.

 

[whartung]

I'm saying that the writers asked Marc Miller about the implications of his jumpspace article and he informed them that jump masking was one of them.

Ok, I can easily see how that conclusion is made, but I won't discuss it here, as it's not really germane to this thread.

Oh, and there's also the canonical background information that the rifts are significant barriers to travel. If capacitors like the Annic Nova's actually existed, that would not be true.

True. If there is an alternate, "less fuel" mechanism to power the jump drive, then the Rifts would not be a problem. The trip may take longer, but not longer than jumping around Rift. Plus the entire premise of hidden caches and protection from Virus for the Regency.

And that's one of the reason why I suggested the "leaky" capacitor idea, or some other thing, that perhaps can get better with TL. Because obviously, in the broad sense, Jump drives take fuel, lots of fuel, all the time. Enough fuel where fleets need tanker trains, drop tanks, hidden fuel caches, etc. in order to operate on the edge.

 

[Blix]

EDIT: The funny thing is if Mac got on the board and made a decision that would be the end of it....we would go with his comments. In the end it is just a game though.

Perhaps you might go with his comments, but unless they agreed with how I choose to run things in my games, I would not remotely care what he (or anyone else) said. While the games I run may be Traveller, they are my own interpretation of the rules and the setting, not his or anyone else's.

 

[McPerth]

How much space do you think all that solar energy collection machinery would take up if there were design rules for it? (hint - the ship plans account for about 430 of its 600t - 170 tons of collection machinery)
Collection machinery that takes 1-6 weeks to fully charge I may add.


The prime power is the one who wrote the adventure in the first place

Let me try to answer you this question using MT rules (as they have solar panels, which CT doesn't, as long as I know). To do so we have to point some facts (and make some asumptions):

-Annic Nova is a 600 dton ship (8100 kl)

-It has jump3 and jump2 drives that can be recharged independently

-Keeping with what's said in Black Globe explanations in combat system, it whould have 202.5 (8100x0.005x2 + 8100x0.005x3) kl of energy sinks.

-Each kl of sinks can store 650 Mw (as in prevous entrys, I assume is Mw h). So the ship's sinks can store 131625 Mw h.

- It takes 1-6 weeks to recharge. I asume that depends on the spectral class and closeness of the star, so I asume that we must calculate 3.5 (588 hours) weeks as an average recharge time.. So we need 223.85 Mw solar PP.

- MT says 1 square meter o solar panel produces 0.081 Mw at TL 12+ (TL 12 is the minimum to have Jump3, so Annic Nova is TL 12+). SO we need 2763.6 square meters of solar panel (minimum).

- 1 square metter of solar panels takes 0.01 kl. So 2763.6 square meters of solar panels whould take 27.636 kl (roughtly 2 dton) probably. We can asume that most of the rest of unaccounted tonnage is devoted to batteries (it has neither PP), some more solar pannels to recharge those batteries and machinery to fold/unfold the solar pannels.

 

[Ishmael]

I'll give it a go to design a 100dton j2 ship as per shadowcat20's example using MT rules as written for solar power.

High Guard page 31 states a ton of capacitors holds 36 EPs or 9000 MW (9GW?) Caps equil .5% of the ships mass times the Jump Number (Same Page).

So a 100 ton J2 ship would require 1 ton of caps or 9000 MW to jump.

So, the target number for power is 9,000mw.
MT limits the total area of solar cells to sqrt(vol) in kiloliters.
sqrt(1350) = 36.74 m2
Each m2 of tech 12 solar cell generates 81,000 joules per 20 minute turn, therefore, 81,000/turn * 3turns/hour * 24hours/day
Each m2 generates 5.832MJ per day.
The total energy with all solar cells is 5.832MJ * 36.74m2 (total solar cell area), or 214.26768MJ per day.
It takes 42 days to charge 9,000MJ or 6 weeks.

now, 81,000MJ/m2 per turn is pretty pathetic.
in the habitable zone, incident radiation is 1370MJ/m2.
1370MJ * 60sec * 20min = 1.644MJ/m2 per turn
This gives tech 12 solar cells only 4.9% efficient... wtf?
Kyrocera has a production solar cell today that gives ~17.3% efficiency.
Crystaline silicon is already approaching ~30%.
Multijunction concentrators are approaching 45%
What might the efficiencies be by tech 12 if these are attainable efficiencies by tech 8?
I'd say that a solar powered j2 100dton ship is possible, especially if 'hi-tech' cells had real world modern day efficiencies.

the same method applied to a 600dton ship means that solar cells would generate 524.88MJ per day ( 90m2 of cells ) or 3.674GJ per week

Now to blow people's minds....
In MT, 1 m3 of tech 12 solar cells gives 100m2 area and thus 8.1Mj per turn and has a mass of .8 tonnes, costing .2Mcr
A tech 12 1 m3 fusion plant produces 8Mj per turn, has a mass of 16 tonnes and costs .8Mcr while using .04 kl/hr of fuel.

 

[shadowcat20]

Interesting, So sails are more efficiant than power plants at certain ranges. Both in space and cost. The downside would be cell degradation due to damage from micro dust, very fragile to damage, and time to deploy and recover.

So we are down to the entire H2 problem.

It is used before the jump, and it is used for power and cooling.

If it was caps for jumps alone every major fleet would have Heavy armored jump ships with J6 and sails. Jump in with 1 Jump left in caps or a spare set of caps to jump out again. No need to refuel, no need for High Guard while the fleet refuels, Add a few fleet tenders with large power plants and a string of fuel tenders and it would make battle riders obsolete.

That would change too much cannon, H2 MUST be in the equation somewhere.

This brings us down to 2 different mind sets, those who want to justify the large cost of tonnage in tankage and those who are trying to get around that cost.

Half the fun of designing ships is the give and take of range vs armor and weapons.

Learned a lot so far. We have about nailed down the capacitor issue for power. Now we need to work on the H2 issue.....

 

[Ishmael]

one bad thing about solar is that your power plant would basically be hung outside and unarmored.
not a good thing for combat

 

[shadowcat20]

Interesting question though, what happens when a laser hits the working surface of a solar cell?

 

[HG_B]

Interesting question though, what happens when a laser hits the working surface of a solar cell?

The panel gets destroyed. Stick your hand in the path of a powerful laser for a demo.

 

[McPerth]

Interesting, So sails are more efficiant than power plants at certain ranges. Both in space and cost. The downside would be cell degradation due to damage from micro dust, very fragile to damage, and time to deploy and recover.

Surprised about that? Solar pannels are considered in most SF the most efficient power plant.

Even so, I don't think they could be practical for a starship. To have lots of power with them you need large surfaces, ans I think they can only be obtained with long arms to support them (as are satellites today).

This can only be obtained (IMO) with dispersed structure configuration, so those ships whouls never be steamlined.

Those ships should have low accelerations, and even less agility (try to maneover with those extended arms, ans you'll see what is left).

Also, those solar pannels are dependant on the sun spertral class and distance, so they probably could not be used much farther from the star than the habitable zone.

I think is for those reasons (and perhaps some others) that ships use fusion power instead of solar pannels, but most planets whould have powersats to harvest solar power, as they are unnafected by most of those limitations.

 

[Xerxeskingofking]

easy, it melts it like it would any other oibject

They're not 100% effecient, and some of that "wasted" energy is comes as waste heat. shoot a laser at it, and it will react as any other shiny surface would.

 

[shadowcat20]

That is what I figured, but I know little about cells.

 

[E.D.Quibell]

Just a quick one about Black Globes.

Under ships combat page 96 of the MT RM, it states:

"If the ship absorbs enough energy to make a jump and is supplied with sufficent fuel, it may jump at the end of the turn."

The question is sufficent fuel for what? to jump? or to run the ship?

I'll check HG when I have a minute to see what CT black globes say.

Best regards,

Ewan

 

[HG_B]

The question is sufficent fuel for what? to jump? or to run the ship?

Fuel for jump. It is stating tech requirements to successfully jump.

 

[rancke]

Fuel for jump. It is stating tech requirements to successfully jump.

True enough. But note the implications. Even with the capacitors full of energy, you still need some "fuel" to be able to jump. Which creates a contradiction no matter how you interpret it.


Hans

 

[shadowcat20]

Yeah, but the JTAS article said fuel was also needed for cooling. If not for the 1 adventure book in CT things would be reasonable....sigh

 

[HG_B]

True enough. But note the implications. Even with the capacitors full of energy, you still need some "fuel" to be able to jump. Which creates a contradiction no matter how you interpret it.


Hans

Depends on the version of Trav you are referencing. In one, the JD is a powerplant and thus needs power throughout the jump to maintain the grid for the trip. In another, the H2 is used to form the bubble.

So, yes & no.

 

[rancke]

Depends on the version of Trav you are referencing.

I don't think so. I could be wrong, but I think that the statement conflicts in one way or another with every single other official version of the jump drive ever described.

Incidentally, the version I'm referring to is the "real" OTU. The (notional) universe that is every bit as complicated as the real world and which the various Traveller rules sets each presents an extremely simplified picture of (As much simpler than the "real" OTU as any historical/modern RPG is simpler than the historical/modern reality of the universe we live in).

That means that if two different sets of Traveller rules say two different, mutually incompatible things, than at least one of them (possibly even both) got it wrong. Just as if the historical RPG Pilgrims & Patriots claims that a ship like the Mayflower has a crew of six and can carry 300 passengers, then it got it wrong. It's not "right for P&P". It's wrong, wrong, wrong. Now, you can probably play P&P perfectly well using those faulty figures, but they'll still be wrong.

Of course, things are complicated a bit by the Traveller Universe being an imaginary universe and "the truth" is therefore subject to retroactive change. But no matter what the truth is changed into, I think it ought to be as selfconsistent as possible. No "all the fuel is used before the jump is initiated" combined with "some of the fuel is used during the jump". One or the other, but not both.



Hans