Why is there a Jump Fuel requirement?

[Reynard]

Back to the original topic.

" I don't know why the jump drive required fuel to do that and not just energy from the power plant, and why does the Maneuver drive require only an energy input, I would thing this arrangement would be the opposite. Why not?"

Depending on the Traveller version, the energy is either generated by the power plant and sent to the jump drive or the jump drive itself has the power conversion capacity. Either way fuel is needed to create energy to create a jump effect.

Again, there are different descriptions as to what the maneuver drive is but all have it as a reactionless event, no mass needed to create movement. Energy is used to create the field or force, whether gravitic and/or interaction with universal quantum forces, to push and pull. There is no hydrogen expelled out the back no matter what the imaginative illustrations show nor is the energy converted to ions or photons for thrust.

Mongoose is interesting that its system requires both power from a source outside the drive AND 'fuel' directly consumed by the drive itself. Just in case I missed it, is there an actual reference that this 'fuel' is used in the bubble? Is this fuel actually used as a really big energy burst needed to create the jump rift and the power plant energy is needed to power the drive's fuel to energy conversion? I think they created the power points game mechanic for 2e but still wanted to retain the classic jump drive fuel requirement. Hey, as long as the ship jumps.

 

[Tom Kalbfus]

Back to the original topic.

" I don't know why the jump drive required fuel to do that and not just energy from the power plant, and why does the Maneuver drive require only an energy input, I would thing this arrangement would be the opposite. Why not?"

Depending on the Traveller version, the energy is either generated by the power plant and sent to the jump drive or the jump drive itself has the power conversion capacity. Either way fuel is needed to create energy to create a jump effect.

Again, there are different descriptions as to what the maneuver drive is but all have it as a reactionless event, no mass needed to create movement. Energy is used to create the field or force, whether gravitic and/or interaction with universal quantum forces, to push and pull. There is no hydrogen expelled out the back no matter what the imaginative illustrations show nor is the energy converted to ions or photons for thrust.

Mongoose is interesting that its system requires both power from a source outside the drive AND 'fuel' directly consumed by the drive itself. Just in case I missed it, is there an actual reference that this 'fuel' is used in the bubble? Is this fuel actually used as a really big energy burst needed to create the jump rift and the power plant energy is needed to power the drive's fuel to energy conversion? I think they created the power points game mechanic for 2e but still wanted to retain the classic jump drive fuel requirement. Hey, as long as the ship jumps.

That would be more energy released than from a thermos nuclear explosion, imagine a nuclear bomb exploding that is in the gigaton range! A little bit of hydrogen goes a long way with fusion. Seems to me that by having a reactionless drive, Traveller was eliminating the fuel requirement for the rocket and then replacing that requirement for Jump fuel, seems to me they could have just left it as a conventional fusion rocket and then added on a Jump Drive with a capacitor that needed charging from the main drive. the 2300 game has a different sort of FTL engine that doesn't require a prodigious amount of fuel, unlike the Jump Drive.

 

[Reynard]

MegaTraveller used capacitors to charge the jump drive. Mongoose used a different physics as many versions have to create a particular game mechanic but most assume tearing a hole in the fabric of reality costs energy and that energy is generated by the futuristic technology of fusion and that needs a lot of fuel. I like the fact they have, over time, included other alternative sources to power the reaction for a jump (as well as alterative means of FTL travel).

 

[Tom Kalbfus]

MegaTraveller used capacitors to charge the jump drive. Mongoose used a different physics as many versions have to create a particular game mechanic but most assume tearing a hole in the fabric of reality costs energy and that energy is generated by the futuristic technology of fusion and that needs a lot of fuel. I like the fact they have, over time, included other alternative sources to power the reaction for a jump (as well as alterative means of FTL travel).

How about ANNIC NOVA? That ship used a solar powered Jump Drive, it used no Jump Fuel at all.

 

[Reynard]

The jump drive is normal. It uses a Collector system to gather and store the exotic particles needed for jump. You can use a fission power plant for power if big enough.

 

[Condottiere]

It's a magic bubble.

But to be fair, what happened to all that hydrogen when you used a lanthanum grid?

 

[Reynard]

Just becomes part of the energy to power the drive. I don't believe the two systems exist in the same universe for whatever version of Traveller being used. I think T5 gives the option to use either/or but a gaming group will have to explain to themselves why both systems would exist at the same time.

 

[baithammer]

T5 allows for both to exist at the same time.

The bubble is simpler in design and allows for variable displacement hulls, such as external cargo, ect.

The disadvantage is due to the debris near a bubble can push the displacement to overload the bubble and misjump or fail.

The grid systems is more complex but allows for closer operation to the d limit and eliminates the debris issue.

It however doesn't work so well with variable displacement hulls.

 

[Condottiere]

I'd allow the lanthanum grid to arrive at the destination faster.

 

[Tom Kalbfus]

Here is an example of a starship without a Jump Drive:

Everything else is there including the fuel for the Jump Drive that was removed. I've recalculated everything, the price of the starship, the amount of cargo space when there is no Jump Drive. The Jump Fuel has been repurposed as power plant fuel, and when I do that this starship has a much greater operating time, about 328 weeks, this is enough to get it up to 0.996959% of the speed of light and then slow it down again. Could it be that this is the reason why there is a Jump Fuel requirement? You see if something were to happen to the Jump Drive, the ship's engineer could simply work on the plumbing to feed the Jump Fuel into the Power Plant to provide 328 weeks of power, and all the reactionless maneuver drive needs is power, so it can continue to accelerate for 328 weeks with this added fuel supply instead of just 4 weeks. You can see the various places this starship can travel to without a Jump Drive, and Traveller has another item called the Low Berth which seems designed for slower than light travel. The journey to Alpha Centauri in a starship which can accelerate continuously at 1-g takes 3.560 years of crew time, while actual elapsed time in the setting for this trip is 5.929 years. Seems like a starship crew with a competent engineer could perform this modification in an emergency involving an irreparable Jump Drive. Was this possibility in the minds of the game designers when they decided to give the Jump Drive a Jump fuel requirement? Seems like this jump fuel alone plus a power plant and maneuver drive still makes this a starship. What do you think?

 

[Reynard]

Ships that take years to travel between even the closest stars will be very different beasts. Oh, by the way, is that acceleration/deceleration or just acceleration for 6 years? Adding decel adds another 6 years. That's a long time to have a crew and 6 passengers in the spartan confines of a Trader. You might consider everyone in suspension, have a virtual crew for mundane monitoring and hope the company hasn't added a routine to explore any alien signals.


Ships making such long journeys will be running well planned missions and carrying every scrap of goods and material needed at the other end while the other end will have materials stockpiled for the return trip. No waste. People will be cargo shipped in low berth to cut life support costs. I see such ships running at half power. The ship themselves will be huge, thousands or tens of thousands of tons.


Colonies in a universe with such long travel times are going to be purpose missioned and very isolated. After the initial build up, the colony will need to be very self sufficient so very few habitats on less than environmentally ideal worlds. That will probably mean large distances between worlds and even greater times for travel. The world used for mineral exports better produce something you can't find in the same quantities in the home system's gas giants and asteroid belts. More often than not, these colonies are to relieve population pressures when the cultures are unwilling to enact population control.


At least digital communications will be slightly faster between worlds.

 

[AnotherDilbert]

Yes, spacecraft can do this. By traditional lore ships can't go faster than ~0.7C or so because of radiation shielding and micrometeorite deflection.

In T5 M-drives only work well in proximity to a star, but there are specific NAFAL drives for sub-light interstellar travel.

Note that the minimum fuel consumption is 1 Dt per four weeks so 41 Dt fuel only lasts 41 × 4 = 164 weeks.

 

[Sigtrygg]

Traditional Traveller OTU lore has a higher speed limit:

Sublight Movement: Sublight movement involves interstellar cruising at speeds approaching 80 to 90% of the speed of light. In game terms, this is a movement of one hex per game turn, executed during the owning player's First Movement Phase.

Imperium boardgame - part of OTU canon;
also:

Sublight movement involves interstellar cruising at 90% of the speed of light. In game terms, this is expressed as a movement of one hex per game-turn, executed during the owning player's First Movement Phase.

Dark nebula boardgame, also part of OTU canon.

Note the increase from 80 to 90% of c in Imperium to 90% as standard in Dark Nebula - TL increses may account for it

 

[Tom Kalbfus]

Yes, spacecraft can do this. By traditional lore ships can't go faster than ~0.7C or so because of radiation shielding and micrometeorite deflection.

In T5 M-drives only work well in proximity to a star, but there are specific NAFAL drives for sub-light interstellar travel.

Note that the minimum fuel consumption is 1 Dt per four weeks so 41 Dt fuel only lasts 41 × 4 = 164 weeks.

I'm assuming the crew goes into low berths for the duration of the trip. as for radiation shielding, most of the radiation will be coming from the front of the ship while it is accelerating and then from the stern of the ship while its decelerating. Since these ships use reactionless drives, it is perfectly okay to have one ship in front of another. So if one employs two ships, one ship can be unmanned and be placed in front of the crewed ship to act as a radiation shield. The cosmic radiation will have to go through the front ship first before it gets to the one behind that. If there is interstellar debris, it will hit the shield ship and then be reduced to a plasma due to the energy of the collision and then can be deflected by a magnetic field. I think STL ships will travel on convoys with the unmanned ships to be used as radiation and debris shields, and the ships will be spread apart far enough so that the plasma created can be dispersed and deflected by magnetic fields. But since reactionless drives are impossible anyway, I guess would could just hand-wave the cosmic radiation as well. I do think Colony Ships will be more common that simple merchant ships. The cost of an interstellar trip per person will be the fractional ownership of the starship that gets you there. In other words divide the cost of the ship new by the number of passengers and customers paying for the interstellar freight shipment. Once the ship makes its first crossing it will be completely paid off by all the passengers and freight shipped between the stars, and if the ship still works, it will either be used as an interplanetary ship at the destination system, or will make the crossing back. I don't think crew members will be paid for the time they are in their low berths, only when they are active. I think much of the crew will end up as colonists anyway, rather than sign on for the trip back.

 

[AnotherDilbert]

Traditional Traveller OTU lore has a higher speed limit:

I stand corrected, thank you.