Fuel costs--jumps vs. weeks of operation

[Master_of_Ritual]

Under Fuel Tank for a ship the main book gives you a total amount of fuel, and a number of weeks of operation that that fuel provides. Is that the number of weeks of operation assuming you don't use the jump drive in that time, and then you recalculate accordingly when you jump?

 

[AndrewW]

Under Fuel Tank for a ship the main book gives you a total amount of fuel, and a number of weeks of operation that that fuel provides. Is that the number of weeks of operation assuming you don't use the jump drive in that time, and then you recalculate accordingly when you jump?

That's weeks of operation for the power plant. Typically the fuel tank holds enough fuel for one jump + power plant fuel.

 

[Reynard]

Calculate them separately then add together for the ship's total fuel capacity. In emergencies, you can use as much of that capacity for real space maneuver and power operations but at the expense of not having enough fuel for a jump. Once a jump happens, the rest is useable for lights. It's not two separate tank systems.

 

[Master_of_Ritual]

Thanks for clarifying, guys.

 

[Condottiere]

Default is pretty simple: ten percent per parsec to be jumped, the balance dependent on fuel consumption by the power plant, which views manoeuvre drive power requirements as overhead.

 

[Garran]

A ship that doesn't jump can run for a very long time on its fuel: even a basic far trader can go for 84 weeks before emptying its tank. This isn't a bug: a ship that isn't making regular jumps is probably going to be staying in system (in whatever capacity) for a long time.

 

[phavoc]

Generally speaking, it's best to have 3-4 weeks of power plant fuel in addition to your jump fuel requirements. A merchant is going to be on the smaller side since merchants are built for profitability and unless there is profit for having lots of fuel, they will never install the tanks.

A military vessel, however, with an expectation of having longer cruise times, will be more likely to carry extra week(s) of fuel for operational flexibility. It will never want to dip into its' jump drive fuel except in emergencies. And having larger tanks is especially more likely for ships that are meant to cruise for longer periods, such as scout ships/cruisers and exploration vessels.

 

[Condottiere]

Squeezing out that last drop.

 

[Linwood]

I could see future systems collecting the 'waste' H2 as well. There are CO2 capture systems now that liquify the gas for use in carbonation and other applications.

Merchants will also want to consider how much insystem travel they may do - for example, between a gas giant and the mainworld. But that's where non-jump ships would have a competitive niche.

 

[Ursus Maior]

Waste H2 off course could be used in fuel processors to generate fuel or be used as such directly (depending on what form of hydrogen ships use as fuel). And CO2 is not really a waste product, but needs to be further processed to be useful again. At TL8+ a star ship should be becoming a biome with certain plant life or highly advanced (bio-)chemical processes using CO2 for oxygen generation (light will be available to some extent when not in jump space, and perhaps even there). And I am pretty certain that carbon is useful at least to waste management companies on planets.

Left-over H2 could even be added to CO2 for nutrient generation or the generation of carbon-hydrogen bonds and the creation of cleaning agents, alcohol, propellants and many more useful chemicals. This would also leave oxygen over as a by-product.

 

[Sigtrygg]

You have access to a multigigawatt fusion power plant. You could use diodes to produce light matched to the exact frequency needed for your photosynthetic processors.

 

[Condottiere]

How realistic are our biodomes in regard to oxygen regeneration?

 

[Linwood]

A (very shallow) internet search suggests an acre of trees can produce enough O2 to support 8 - 18 people per year while an acre of grass may produce enough O2 for up to 70 people per year. Definitely an instance where YMMV.

Likely biodomes would grow specially-bioengineered organisms optimized for super-efficient O2 production. Or they would be really large ships with really tiny crews. Most likely the biome would be a supplemental O2 generation system, possibly considered desirable because the ship's atmosphere will feel more 'natural' to the crew, thus boosting morale on long missions.

 

[Linwood]

Thinking about this a little differently -https://medium.com/@candidegardening/how-many-plants-would-it-take-to-produce-enough-oxygen-for-one-person-7312743ed70b

So figure you need 700 houseplants per crew member to be completely O2 self-sufficient. Or some really extreme bio-engineered organisms.

A space station or frontier outpost based on this would make an interesting adventure setting. Not so sure it would make for a practical small interstellar freighter...

 

[Ursus Maior]

I would think plant life would usually supplant artificial systems for reasons of space efficiency. But as mentioned, it boosts morale by feeling more natural. Plus, mixed systems might include hidden or invisible parts, like algae growing in tanks that are fed light and waste water to produce oxygen and convert waste products into more useful things like food etc. Hydroponics, aeroponics, aquaponics and anthroponics are viable part of agro-industries already today. Mixing water, human waste products, water borne animal life, standard atmospheres and different gravity levels will become a major factor in space travelling in the near future.

For Traveller the question is just, how designers imagine TL10-15 ships to work. This is the realm of space magic really from our point of view. Either the decision is that these technologies are integrated into every design - visibly or invisibly - as part of standard life support systems, but below the level of Highguards proper 'biosphere' option, or the decision is that this is not the case, because it's to expensive relative to its efficiency. Either way, life support systems somehow work the way they do and the technology behind them is either purely artificial or a mix of technologies.

 

[Condottiere]

Artificial resuscitation is more efficient, and space tends to be one of the principal constraining factors in Traveller ship design.

It becomes really interesting because of the cost of life support, and it's elimination, going by the design rules.

I'm doing some repotting at the moment, and you could cover a two metre by two metre wall with a hundred houseplants.

 

[NOLATrav]

I prefer to think of Trav standard life support as being whatever is most efficient, cheapest and easiest for a given tech level. In player terms, it’s Engineering (life support) that handles the day to day. In my mind this is a lot of filter/cartridge/membrane replacement and maintenance on machines, sensors and computer sub programs that actually do the work.

This saves the hydro/aqua/aeroponics stuff for characters with Science (whatever), and we work out the contribution it brings to the table, whether that’s actually edibles, or maybe just a reduction of monthly ship overhead. We’ve also used Profession (farming) for instance to allow a reduction of LS overhead.

Personally I find Traveller ship expenses to be way too high for a society with fusion tech; it feels like a holdover from the Classic era thinking and no one really seems into the free trader/accounting game anymore anyway. I still haven’t made up my mind about fuel costs - all those Hydro 0, Poor worlds with C and B ports bringing in fuel from the local gas giant should be charging quite a bit more than the book rates IMO, and a world like Regina (a relatively high tech world orbiting a gas giant) should be charging pennies compared to her neighbors.

 

[Condottiere]

The three essentials are oxygen, water and heat.

Heat appears to be more of a problem to get rid off.

Starships tends to have tonnes of tanks that you can fill with water. Or the crew can wear stillsuits.

Which leaves us with oxygen, usually handled by filtering the carbon dioxide and restoring breathable air.

Am I leaving anything out, besides instant noodles?

 

[Linwood]

Ummm - nutrients?

 

[Condottiere]