Just how does a Jump Drive work re: Power/Fuel

[DickNervous]

First off, I don't want to get into a super gear-headed discussion of how a Jump drive gets you from point A to point B, mainly because I know that I would be totally lost by the 2nd or 3rd post and look like this guy ->

No, what I want to know is the higher level concept of how jump drives work in relation to power and fuel requirements. I am primarily interested in MgT (both 1st and 2nd Edition) since that is what I play, but I do want to know how other versions of Traveller handle it. I will start off with describing how I thought it worked until some recent reading and discussions made me start to doubt myself.

First, a very simplified description of how I think "jumping" works...

Making a ship jump requires a LOT of energy that is all expended at the time the jump is initiated. This creates the "jump bubble" that allows the ship to travel great distances. After that the only power requirements of the ship is for the general operation (life support, etc) during the time the ship is in jump. When the ship arrives at it's destination that "jump bubble" "pops" releasing a significant amount of that energy into space which is what sensors might see when they detect a ship arriving in a system.

In a standard ship I have always assumed that the power plant provides the power to the jump drive by burning the required amount of fuel and "charging" the drive up. Then after the course is plotted and all parties make the required checks the jump is "triggered" and off you go. However, while working on the design of the Normandy Class Stealth Scout, talking to others, and reading the MgT2 ship design books I have come to think that I might be wrong in that assumption.

So I decided to check it out and found conflicting information. These quotes support the fuel-direct-to-jump-drive method:

Total fuel storage for a ship must be indicated in the design plans.
There is no cost, but the capacity does influence how often the
ship must refuel. Ships in Traveller use the same fuel – hydrogen
– to power both the Jump drive and the power plant – the main
difference is how much they use up. (MgT Core, pg 107)

Jump Drives
The fuel tankage needed for a jump drive is related to the size of the ship and the length of the jump, as follows;

10% of the total tonnage of the ship, multiplied by the maximum jump score of the drive

The result of this is the number of tons that needs to be dedicated to jump fuel. MgT2 Beta High Guard, 02 - Ship Design, pg 6)

This quote from CT and a diagram I found from MegaTraveller both support the Power Plant supplying the power:

A ship requires fuel for its jump drives and for its power plant; the power plant converts fuel to energy for computers, jump drives, maneuver drives, weapons, and screens.(CT B05 High Guard 1980, pg 22)

And these two from Traveller5 seem to contradict each other and support both ideas....

Ships require a power source to support its drives and
routine operations. Power Systems process fuel (or do other
things) to provide the energy required.

Jump Fuel. Fuel equal to 10% of Hull times the Jump in
parsecs is required at the initiation of Jump. (Traveller5, pg 319)

So my question is, which way is it supposed to work: Does the Jump Drive draw the required power from the ship's power plant or does it burn the fuel directly? (Or is it one of those things that is left to the GM to decide?)

 

[mike wightman]

Once upon a time the jump drive didn't need a power plant as well - see the original x-boat.
Then the rules were changed to the jump drive requiring an installed power plant of equal rating to the jump drive.
Then in MegaTraveller it went back to jump drives not needing a power plant, stayed that way for a while (TNE, T4, GT, GT:ISW) and then it went back to jump drives requiring a power plant in subsequent editions (T20, MgT, T5).

One thing has remained constant (apart from MegaTraveller) - the jump drive requires fuel equal to 10% of the hull volume per jump number.

In CT HG2 a ship could power up its jump drive using energy acquired from a black globe, but there is an interesting line that says it can only jump if it has the required jump fuel to do so, despite charging the jump capacitors with the black globe.

This has lead many to the following conclusion(s):
to prep for a jump the jump capacitors must be charged - this is probably done routinely by the power plant
to initiate the jump the jump fuel is used to do something, either coolant for the coils/hull grid(delete as applicable to your rules of choice) as the ship makes the jump hole it drops into; some say it is used to create a bubble of normal space that protects the ship from jump space; others say all the fuel is used at the time of jump to initiate a massive power spike for the jump drive.

And now to answer your real question - no you can not use an antimatter power plant without also using hydrogen jump fuel until around the TL18+ (at least in the T5 OTU, in your version of the Traveller 'verse it can work anyway you want it to; supplementary note - using experimental or prototype AM plants you could get this down to TL16).

My pet theory is that the massive amount of fuel is used as a combination of coolant and as a way of generating a massive energy spike to generate the exotic particles needed to open the jump hole.

Collectors work by collecting these exotic particles from space itself, but that requires a massive capacitor and collector array.

The matter/antimatter annihilation must also produce these exotic particles, but more efficiently than fusion reactions.

 

[robject]

There is a self-contained jump drive that requires no power plant. However, it has never been explained in any rule set so far.

For every jump drive we know how to use in ship design, the power plant burns the fuel. And, antimatter can be used to power jump without hydrogen fuel.

 

[mike wightman]

Since when?

In MT you don't even need a power plant to power the jump drive.

The MT SOM info on the jump drive actually states that the jump drive uses the hydrogen fuel and has a fast burn reactor built in.

Every rule set says the jump drive requires hydrogen fuel to actually jump, except for collectors and antimatter plants in T5.

The later rule sets which go into details say the jump drive requires power during the time in jump space, this can be an antimatter.

But they all agree - you must have hydrogen fuel to actually jump (except the collector and T5 AM).

Oddly enough Marc's original Jump space article mentions that jump drives can be powered by fusion, collectors or antimatter.

 

[kilemall]

A further subtlety is that CT HG2 has fuel drop tanks for jump, indicating that the fuel is at a minimum all loaded into the jump drive at jump initiation.

Now whether it is all burned/used right then, in there fueling the jump drive for the whole jump, or partially burned and partially used for X process, is a very open question.

The whole question led me to muon catalyzed fusion as being involved, since that is a technology that would tend to greatly compress the volume of the fuel into a jump drive sized space.

https://en.wikipedia.org/wiki/Muon-catalyzed_fusion

 

[Condottiere]

As I understand the coming game mechanism, everything happens in the six minutes preceding the jump.

The energy points expended equal the tonnage of the fuel released into the jump bubble, and the starship coasts along until it plops out at it's calculated exit point, energy usage sufficient to run basic ship systems for the next week or so.

 

[whartung]

Nobody knows.

No, really.

Nobody knows. And anyone who "does know" refuses to say.

Where or how "10% per jump" fuel is used (save for TNE, natch), is undefined.

If you want to wrap your head around the "6 minute" number, imagine a 100K ton ship doing jump 6, 60K tons of fuel in 6 minutes. It must consume a swimming pool full of LHyd PER SECOND. Niagra Falls is just over 2 swimming pools/sec.

Back in the day, you could use Solar Power to jump. Back in the day, you could use Jump Capacitors to jump. But if you allow that, then the whole "10%/Jump" issue explode in to different ship designs and other things.

So, the reason we use 10%/jump is because the rules say so.

I've never seen a PP requirement for Jump drives. TNE doesn't have one, HG doesn't have one. Can't speak to MgT[12]

 

[McPerth]

There is a self-contained jump drive that requires no power plant. However, it has never been explained in any rule set so far.

The only one I know abaut is Annic Nova's...

For every jump drive we know how to use in ship design, the power plant burns the fuel. And, antimatter can be used to power jump without hydrogen fuel.

Maybe that is true in T5 (I don't know it), but in former versions that was not. In CT/MT, even if the ship has the capacitors full due to Black Globe, it is staed that it needs the fuel to jump, hinting that power is not enough.

 

[robject]

The only one I know abaut is Annic Nova's...

And the Xboat, which Mike mentioned earlier.

Maybe that is true in T5 (I don't know it), but in former versions that was not. In CT/MT, even if the ship has the capacitors full due to Black Globe, it is staed that it needs the fuel to jump, hinting that power is not enough.

You're correct about version non-uniformity. That's why I'm quoting T5.

By the way: T5 doesn't mention the standalone jump drive, but Marc has mentioned it. I'm looking for his reference to it in my email... here it is, from 2012: "Self-processing jump drive. Less tonnage than J+P but (insert drawback here)."

While I'm on about the Xboat: Marc doesn't mind if it has a maneuver drive. His quote: " “stripped-down” is all we really need."

He then suggested:

The decision to not have a maneuver drive was a top-down political decision.

Hmmm. What if we left out the maneuver drive?
(thinking… that’s stupid) (Saying “Yes, sir, that’s brilliant! You’ve solved the problem!).

 

[McPerth]

And the Xboat, which Mike mentioned earlier.

Sorry, I cut your post where I shouldn't.

I was refereing to hydrogen fuel, not to PP. Any MT ship can jump without needing the PP for it.

 

[Spartan159]

Per MgT²: Jump travel is the only known means by which a vessel may travel faster than light. To jump, a ship creates a bubble of hyperspace by means of injecting highenergy 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.

I for one will be totally ignoring the heck out of the hydrogen jump bubble theory, IMTU I can do what I want and that's one of them. FWIW I ignore the rule about needing fuel with a fully charged capacitor as well. Just my 2 credits worth.

 

[robject]

Sorry, I cut your post where I shouldn't.

I was refereing to hydrogen fuel, not to PP. Any MT ship can jump without needing the PP for it.

No worries. Yeah, as I mentioned, there is rules non-uniformity that drives us grognards to distraction.

 

[DickNervous]

First, thanks to everyone who has replied so far. I feel much better being confused about this after seeing that everyone has a different answer and there doesn't seem to be a right or wrong one.

So I have did a bit more digging and I have found a few other things. From the Traveller Wiki I found the following, both of which appear to support the "you must have fuel to jump" theory, except they don't.

Fuel Requirements
Starships must generate immense amounts of power to jump, and therefore additional fuel must be allocated for employment of the jump drive at the rate of 10% of the ship's tonnage per parsec to travel via jump. 1% of ship volume per jump number the drive is rated for is dedicated to accumulators, ie jump drive super capacitors. (High Guard, black globe rules declares specifics.)

A significant amount of the fuel consumed during charge to jump is actually used to supercool the reactor while it is in overload mode; more than normal is used as fuel itself, as overload mode is less efficent than normal mode in fuel use, and ship plants are less efficent than stationary power systems to begin with.(Traveller Wiki, Jump Drive)

This one states that a significant amount of fuel is used to supercool the reactor while it is charging, but it doesn't specify if that reactor is the standard power plant of part of the Jump Drive. Which means that if you have a reactor that is capable of generating the required power fast enough without over-heating you shouldn't need all that extra fuel.

Starships must generate immense amounts of power to jump, and therefore additional fuel must be allocated for employment of the jump drive at the rate of 10% of the ship's tonnage per parsec to travel via jump. Much attention has been paid to this in an attempt to reduce it. However, due to the tradeoffs of power system design to get this much power output in this small a space, and the cost and size of a large high efficiency plant, the optimum solution is a small plant that can operate at vastly higher output for short periods, and a large consumption of much cheaper fuel.

The critical bottleneck defining the general limitations everything else must conform to is the short time one can store that much power in a super-capacitor before it breaks down from the stress. This means the ship must generate all the power to use in jump within a half an hour before discharging it into the drive proper. Several experimental ships in the early days exploded due to capacitor failure. Only a capacitor is able to discharge it's energy store this rapidly, batteries of the electrochemical sort simply cannot serve in this manner of application.(Traveller Wiki, Jump Drive History)

This one also simply states that it is a tradeoff to use huge amounts of cheap fuel instead of a very high efficiency power plant in a ship. This would again indicate that the amount of fuel required is based on the type of fuel and the efficiency of the power plant generating the power.

So of course, this doesn't exactly help answer the question I posed, but combined with what others have said I have come to the following conclusions:

1. While not specifically stated it is implied in many sources that jump drives DO NOT consume fuel directly.

2. A Power Plant that is based upon a "standard technology" (fusion, fission, chemical, solar, etc) such as it typically available below TL15 is not capable of generating the power required for a jump in the required time without going into "overload" and therefore will require additional fuel to both be consumed and cool the reactor.

3. A Power Plant that uses different power generation method (TL16+) such as Antimatter, black globes, black holes, etc. MIGHT be capable of generating enough power in the appropriate time period to activate a jump drive without any additional fuel. This is neither denied or confirmed in any published materials that I have been able to find at this time.

I think the bottom line is that nobody has ever published anything definitive or detailed enough regarding some of the technology that is possible above TL15. Of course I could be completely off my rocker. :rofl:

And of course, the real beauty as others have mentioned, is that we can all do whatever we like in IMTU.

 

[Condottiere]

There are several ways to enter hyperspace.

Why there is this emphasis on a huge hydrogen consumption isn't quite clear, beyond a game mechanism to force a compromise between range and normal space performance.

If using pure energy as a means to transition was an alternative, warships would immediately drop the bunkerage, since having that large power reserve serves them in their primary role to shoot stuff up.

 

[kilemall]

I'm not sure where you are getting the 'jump drive doesn't consume fuel' assertion, CT HG2 at a minimum clearly uses the whole tankage else the fuel tank drops wouldn't work or there would not be a need for them.

A subtle implication is that with the dropping of the tanks volume of the ship to jump drops, so again volume of ship x parsecs to jump at once is the defining factor, no matter the 'actual' pseudo-engineering reason.

That wiki jump drive history to my knowledge is largely speculation and another 'take' on the process.

 

[whulorigan]

I'm not sure where you are getting the 'jump drive doesn't consume fuel' assertion, CT HG2 at a minimum clearly uses the whole tankage else the fuel tank drops wouldn't work or there would not be a need for them.

A subtle implication is that with the dropping of the tanks volume of the ship to jump drops, so again volume of ship x parsecs to jump at once is the defining factor, no matter the 'actual' pseudo-engineering reason.

That wiki jump drive history to my knowledge is largely speculation and another 'take' on the process.

I think the distinction he is making is the difference between the Jump Drives using the fuel directly in some way, versus the Power Plant using the said fuel at a high consumption rate in order to power the drive.

 

[aramis]

One thing has remained constant (apart from MegaTraveller) - the jump drive requires fuel equal to 10% of the hull volume per jump number.

Try, except in MT, TNE, T4, and GT...

MT, it's not linked to the JD requirements, and is measured in kiloliters (cubi meters) per week per kiloliter of drive.

In TNE, the PP requirements are in kL per year, as is T4.

 

[McPerth]

This one also simply states that it is a tradeoff to use huge amounts of cheap fuel instead of a very high efficiency power plant in a ship. This would again indicate that the amount of fuel required is based on the type of fuel and the efficiency of the power plant generating the power.

This would be coherent with MT decreased jump fuel needs as TL gows up, but even at higher TLs, where antimatter is usual power source, JD still requires fuel (albeit at lower quantities).

 

[Condottiere]

Hydrogen eats metal for breakfast, and the ship is bathing in the stuff for a week at a time.

 

[kilemall]

Hydrogen eats metal for breakfast, and the ship is bathing in the stuff for a week at a time.

Who says fuel tanks are metal?

I had in mind some near zero carbon synthetic with very tight bonding and a repulsion charge to prevent leakage.

Certainly would explain why they lose so much per hit, along with some king hell needs to pump it all into the jump drives fast (so they need to be big and contiguous, 300 fuel tanks would be great for damage limitation but incur that much more piping and pump arrangements).