Liquid Hydrogen Jump Bubble

[Timerover51]

Where is the concept of the Liquid Hydrogen Jump Bubble mentioned?

How is it maintained as a liquid bubble in the vacuum of space prior to jump?

How many ejection ports are required to get an evenly distributed bubble around a ship, and where is the cost for the piping, insulation, pumps, and ejection ports reflected in the cost of the ship?

For very large ships, say the 500,000 dTon dreadnought, you are looking at massive tonnages of Liquid Hydrogen being moved about and dumped overboard in a very short period of time.

 

[Blue Ghost]

Where is the concept of the Liquid Hydrogen Jump Bubble mentioned?

How is it maintained as a liquid bubble in the vacuum of space prior to jump?

How many ejection ports are required to get an evenly distributed bubble around a ship, and where is the cost for the piping, insulation, pumps, and ejection ports reflected in the cost of the ship?

For very large ships, say the 500,000 dTon dreadnought, you are looking at massive tonnages of Liquid Hydrogen being moved about and dumped overboard in a very short period of time.

I seem to recall that the LH reference referred to the ship's fuel, and not really the bubble itself.

 

[Timerover51]

I seem to recall that the LH reference referred to the ship's fuel, and not really the bubble itself.

Would you care to consider either how much energy is in TONS of Liquid Hydrogen or how incredibly inefficient the fusion power plant must be?

We are talking THOUSANDS OF MEGATONS of energy equivalent here.

 

[whulorigan]

Would you care to consider either how much energy is in TONS of Liquid Hydrogen or how incredibly inefficient the fusion power plant must be?

We are talking THOUSANDS OF MEGATONS of energy equivalent here.

I think the point that Blue Ghost is referencing is that the Hydrogen is stored internally as LHyd as a significant proportion of the "Jump-fuel" in the tanks, but when it is vented for the "Hydrogen Bubble", it does not remain LHyd (presumably) but evaporates into a gas-envelope within the Jump Bubble.

In answer to your earlier question, the Hydrogen Bubble is mentioned in MT/DG: Starship Operator's Manual.

 

[Fovean]

Mongoose also makes use of a hydrogen jump bubble, the energy in the fuel being used to open the rip into jump space, maintain the bubble of normal space around the ship while in jump and re-open normal space as the jump ends and the bubble dissipates.

MgT Core rules, pg 141

 

[Timerover51]

Hmm, I think that in My Traveller Universe, the excessive amount of fuel for jump is finally getting the "Deep Six" or "File Thirteen" treatment, as it simply makes no sense whatsoever. I am thinking of replacing it with large amounts, in terms of Mass, capacitors, or going with a slower version of Piper's hyperspace drive.

Also, no one has addressed the issue of the massive amounts of piping, insulation, and ejection ports, and their costs, for this Jump Bubble.

 

[Fovean]

I think the concerns of costs and logistics for jump bubble mechanics are below the granularity of the rules and are subsumed into the cost and tonnage of the jump drive itself.

Others have postulated that the large amounts of jump fuel (well, all hydrogen fuel in Traveller I suppose) is actually used as coolant for the power plant and drives and evacuated as it is used. This presumably solves the 'internal heat build-up' conundrum associated with Traveller spacecraft.

 

[aramis]

Would you care to consider either how much energy is in TONS of Liquid Hydrogen or how incredibly inefficient the fusion power plant must be?

We are talking THOUSANDS OF MEGATONS of energy equivalent here.

The efficiency has repeatedly been worked out to about 0.01% of the energy of fusion... We can measure the output of D+D and T+T fusion now (scientists have been able to cause it to happen in the lab for 20 years)... what we, at our present approximately TL8 cannot yet do is recapture enough of it to run the apparatus causing the fusion.

Present real world fission plants are about -0.5% (notice the negative sign) net efficiency - energy out is about 99.5% of energy spent initiating it, IIRC the articles from early 2014.

There is little real world reason to complain at all about the efficiency. The expectations of many science geeks are that initiation energy will ALWAYS been ≥99% of energy recaptured.

 

[Meeko100]

Hmm, I think that in My Traveller Universe, the excessive amount of fuel for jump is finally getting the "Deep Six" or "File Thirteen" treatment, as it simply makes no sense whatsoever. I am thinking of replacing it with large amounts, in terms of Mass, capacitors, or going with a slower version of Piper's hyperspace drive.

Also, no one has addressed the issue of the massive amounts of piping, insulation, and ejection ports, and their costs, for this Jump Bubble.

It likely is just vented from the fuel tanks and surrounds the vessel. Its there likely to just act as a buffer from jumpspace to the realspace (if there's that distinction) of your spaceship. Doesn't need to be perfectly sphereical

It likely is under significant pressure to be force into liquid instead of gas, so it pops out easy, and surrounds the ship as hydrogen gas.

Any other equipment to hook into the jump drive likely is included in the weight/cost of the drive, and is assumed to be a unnecessary point to make.

I imagine the insulation between the fuel and the rest of the spaceship is included from the rest of the ship as needed, and just isn't worth keeping track of. Or the writers thought so.

I personally dont like the jump drive too much. I prefer the idea of a hyperdrive, going into another universe, driving around in there, and coming out when you get where you need to be. How am I getting around in said other universe with a j-drive?

 

[Blue Ghost]

I vaguely remember the reference in the SOM. In fact when I read it all those years ago I thought it went counter to established canon, or, more likely, was a variation on jump tech and not strictly speaking how all nor even most starships in Traveller performed jumps.

 

[rancke]

My original concept was that jumpspace was denser than our unisverse so that slamming across the dimensional barrier would smash the ship, much like hitting the surface of the sea at high speed would cause the water to act as rigid as steel. So the starship opened a small aperture into jumpspace and injected a lot of hydrogen, creating a bubble of "soft" jumpspace. The bubble would dissipate in 40 minutes.


Hans

 

[Timerover51]

I think the concerns of costs and logistics for jump bubble mechanics are below the granularity of the rules and are subsumed into the cost and tonnage of the jump drive itself.

Others have postulated that the large amounts of jump fuel (well, all hydrogen fuel in Traveller I suppose) is actually used as coolant for the power plant and drives and evacuated as it is used. This presumably solves the 'internal heat build-up' conundrum associated with Traveller spacecraft.

If that is the case, where is that spelled out anywhere in the various rule sets. All of them refer to the Liquid Hydrogen as fuel, not coolant.

As for the comment about the mass for piping, insulation, and pumps in the jump drive mass and cost, that is a flat increase in mass and cost for every increment of jump drive. I do not buy that in the least.

 

[rancke]

If that is the case, where is that spelled out anywhere in the various rule sets. All of them refer to the Liquid Hydrogen as fuel, not coolant.

Because that was the original concept.

I believe MgT tries to address the inherent silliness, but not with any great success.


Hans

 

[Murphy]

IMTU:
Over the course of a week hydrogen is vented overboard slowly, in a controlled fashion, to prevent the jump bubble from collapsing. Essentially you "feed" the jumpspace with hydrogen to keep it from swallowing your ship while you are in transit.

You can't use just any gas instead of hydrogen because it is vastly less economical with heavier elements, and any mix of elements (including impure hydrogen) creates instabilities: some of your exterior will end up damaged by the deformed jump bubble, and your jumpspace course may be altered (misjump).

If the venting stops, the bubble collapses, destroying the ship. All ships thus have multiple backups for that system to continue functioning at any cost during jump.

 

[rancke]

IMTU:
Over the course of a week hydrogen is vented overboard slowly to prevent the jump bubble from collapsing. Essentially you "feed" the jumpspace with hydrogen to keep it from swallowing your ship while you are in transit.

Unfortunately that won't work for the OTU. The way drop tanks work makes it clear that all jump fuel is used prior to entering jumpspace.

If the venting stops, the bubble collapses, destroying the ship. All ships thus have multiple backups for that system to continue functioning at any cost during jump.

So if the jump is problem-free, you arrive with your jump tanks partly filled? How much of the traditional amount of fuel is backup? IYTU, that is?


Hans

 

[Azezel]

So if the jump is problem-free, you arrive with your jump tanks partly filled? How much of the traditional amount of fuel is backup? IYTU, that is?


Hans

I think he means the venting system is multiply redundant, not that ships carry more fuel than they need.



Anyhoo - Timerover, it seems you've decided that you don't like the jump and fuel concepts as presented (which is okay!) and nothing anyone says will change your mind.


However, the closest to cannonical function (given that different editions have said different things) is that:

1: You hits you the JUMP button and the powerplant goes into 'overload' mode, drinking down a big gulp of fuel to power the Jump Drive.

2: Because the PP is overloading some more fuel (at less than 33k) is used to cool the PP and vented into space.

3: The JD creates a tiny pocket of Normal space in Jump space and yet more fuel is used to 'inflate' this bubble to a volume big enough to contain your ship. Incidentally, it would seem to be step three that makes refined fuel important.

The reason why ships need so much 'fuel' to jump is because most of it actually isn't used as fuel, it's used for steps 2 and 3. Though of course, a lot of the details change depending on which of the million or so versions of Trav you're playing this week.

 

[rancke]

I think he means the venting system is multiply redundant, not that ships carry more fuel than they need.

But it would have to. To begin with there's the standard jump variation. Jumps take 168 +/- 17 hours. At the very least a ship would have to carry enough protective hydrogen for 185 hours, which would leave something over for the average jump. And then there are the misjumps that add several days to a jump. Wouldn't a ship want to carry enough hydrogen to survive that?

Anyhoo - Timerover, it seems you've decided that you don't like the jump and fuel concepts as presented (which is okay!) and nothing anyone says will change your mind.

Probably because there's no way to account for the jump and fuel concepts as presented. The best you can do is ignore the problems.

2: Because the PP is overloading some more fuel (at less than 33k) is used to cool the PP and vented into space.

Unfortunately for that theory there are liquids that are far better (in terms of effect per volume) for cooling purposes than Lhyd. Water, for instance.


Hans

 

[Azezel]

But it would have to. To begin with there's the standard jump variation. Jumps take 168 +/- 17 hours. At the very least a ship would have to carry enough protective hydrogen for 185 hours, which would leave something over for the average jump. And then there are the misjumps that add several days to a jump. Wouldn't a ship want to carry enough hydrogen to survive that?

I agree. I was just clarifying what (i think) Murphy meant).

Probably because there's no way to account for the jump and fuel concepts as presented. The best you can do is ignore the problems.

I agree, but the general concept I laid out works of you don't look too closely. It works better than some other parts of the OTU, anyway.

Unfortunately for that theory there are liquids that are far better (in terms of effect per volume) for cooling purposes than Lhyd. Water, for instance

I... agree.

But it's easier to use Hydrogen since you're already carrying that.

The long and short is all methods of FTL have insurmountable flaws so you just have to pick one and try not to poke it too hard.

It's more important that the economic and political models of MTU work than the Jump Drives.

 

[Murphy]

Unfortunately that won't work for the OTU. The way drop tanks work makes it clear that all jump fuel is used prior to entering jumpspace.

Agreed. I got rid of the drop-tank concept altogether.

So if the jump is problem-free, you arrive with your jump tanks partly filled? How much of the traditional amount of fuel is backup? IYTU, that is?

I meant it more like, if the flow stops, automated systems switch to backup flow control. I wasn't referring to backup tanks.

That said, IMTU most starships do carry at least 1/3 their displacement in LH2 -- but that's because it is used as reaction mass. (IMTU, gravitic drive is just a glorified mass driver -- gravitics can't break Newton's third law).

 

[Ishmael]

If that is the case, where is that spelled out anywhere in the various rule sets. All of them refer to the Liquid Hydrogen as fuel, not coolant.

Starship operator's Manual
"The heat is vented via a series of thermal transfer techniques: superconducting hull radiators built into the hull and convection techniques using some of the liquid hydrogen fuel as coolant and expelling it with the fusion byproducts out the rear of the ship."

Fire, Fusion, and Steel 1
"Jump drives require fuel, displacement mass, and coolant, all of which are collectively called jump fuel ( liquid hydrogen being used for all three functions )."

Fire Fusion and Steel 2 has the earliest mention of hydrogen formed jump bubbles that I can find.