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Kirk Andersen
United States
Athens
Tennessee
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It seems to me the need for travel in the Traveller universe is going to be governed by the need for fuel. Is there a tried-and-true method for figuring fuel consumption for starships in the Traveller classic rules (for maneuver and jump drives)?
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James Lowry
United States
Sunnyvale
California
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I'd have to look it up for maneuver drives and reactor plant, but jump drive is very simple: 10% of the ship's internal volume is consumed in fuel per parsec of travel. It doesn't matter if you make one two-parsec jump, or two one parsec-jumps, the fuel consumed would take up volume equal to 20% of the ship's internal volume either way.
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Art Gorski
United States
Prescott
Arizona
Get my Mac software for Classic Traveller at http://naasirka.weebly.com/
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Yes, but good luck finding it. Can't remember where the jump fuel calculations are, although it's related to a discussion of fuel usage of multiple small jumps vs one big jump.
For maneuver drive fuel usage, there's a nifty table in Beltstrike.
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Steven Ege
United States
Fall River
Massachusetts
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Rindis wrote: I'd have to look it up for maneuver drives and reactor plant, but jump drive is very simple: 10% of the ship's internal volume is consumed in fuel per parsec of travel. It doesn't matter if you make one two-parsec jump, or two one parsec-jumps, the fuel consumed would take up volume equal to 20% of the ship's internal volume either way.
Jump Drive: 0.1 x M x Jn, where M is the ship tonnage and JN is the Jump number.
Power Plant: 10 x Pn, where Pn is the Power Plant installed.
Maneuver Drive: No formula.
High Guard makes it clear though that the tankage for the power plant also covers the maneuver drive, and that the fuel tankage is sufficient for four weeks' operation.
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I've always considered calculating the fuel usage for non-jump based stuff a waste of time. Just track it for jumps. Only worry about the other stuff when you want to make a plot point. And if you're making a plot point, don't make it a maths problem, just tell the players...
"You don't have enough fuel to reach the station!"
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Kirk Andersen
United States
Athens
Tennessee
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It's not really that hard to calculate maneuver drive fuel even when there is a time element involved. In Book 2, (Starships) two tables (typical distance and travel times tables) make figuring the times involved in travelling with the maneuver drive quite easy. There is also a table of in-system travel times in the referee's companion supplement in the Megatraveller game books.
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Kirk Andersen
United States
Athens
Tennessee
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I don't think you multiply the jump rating of the ship into the calculation of the jump fuel. For example, if you have a ship with a jump rating of 2 it can go twice as far on the same amount of fuel as say a ship with a jump rating of 1(if they have the same tonnage and fuel capacity). That's why the far trader is called the "far" trader. It has a higher ability to go long distances without refueling(it has a jump rating of 2) than say the free trader (jump rating of 1).
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Steven Ege
United States
Fall River
Massachusetts
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You have made an erroneous assumption in your thinking: the fuel capacity is a constant. It's not, and actually working with the formula proves it's not. The formulas come from the starship design section of The Traveller Book. When building a ship you must have sufficient fuel to support the maximum rating of the Jump Drive. Let's take a 600-ton ship capable of jump-3 and a 600-ton ship capable of jump-4.
0.1 x 600 x 3 = 180 tons fuel required
0.1 x 600 x 4 = 240 tons fuel required
That is the amount of tonnage that must be reserved for each ship to be able to perform the jump. It doesn't matter if it's broken down into three or four jump-1 jumps, or one jump-1 and one jump-2, so long as there's enough fuel to cover the maximum. As you can see above, the jump-4 vessel can travel further than the jump-3 vessel at the cost of increased fuel tonnage. Using your example, the jump-1 free trader would require 20 tons of fuel tankage to support the Jump Drive. The jump-2 far trader would require 40 tons, which would require the far trader's designer to sacrifice cargo space or a couple staterooms to make up the difference. Everything must balance and must fit within that hull.
Make sense?
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Kirk Andersen
United States
Athens
Tennessee
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Oh I understand what the rules say about calculating fuel consumption for jump drives I just don't agree with them. I have my own "house rule" for calculating jump drive fuel consumption that incorporates the fact that if two ships have the same tonnage the ship with a larger jump rating can go a farther distance on the same amount of fuel than a ship with a lower jump rating. The reason for this is in the stats for a survey ship in the Fighting ships supplement. If you go by your formula the survey ship would have to refuel after just three parsecs of travel. This doesn't make any sense because a survey ship is an exploratory vessel that should be able to travel long distances without refueling. In my house rule you simply take 10% of the ships tonnage to calculate the jump drive fuel in tons and if the ship has a jump rating of 3 it can travel three parsecs on that amount. So with my house rule a survey ship can travel 9 parsecs before having to refuel again. A far trader could travel 4 parsecs instead of 2 before having to refuel again. And so on. All of this is assuming that the fuel capacity of each ship is how much the ship's tank can hold in fuel in tons. This is the number in every high guard Universal Ship Profile listed after the word "fuel". Such as fuel:40. Maybe I'm just not getting the concept of fuel capacity right.Basically my formula leaves out the jump rating multiplier.
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Steven Ege
United States
Fall River
Massachusetts
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You asked for the formulas for fuel tankage and were given them straight from the book (the RAW). After being given them, you said, "I don't think you multiply the jump rating of the ship into the calculation of the jump fuel." You then spent the rest of your post justifying your statement.
Disagreeing with the concepts behind the RAW is perfectly acceptable, but instead of saying that you didn't agree with the RAW you declared the RAW itself to be wrong. I take a rather dim view of that, but I digress.
To actually respond to your post, regardless of whether the Book 2/TTB formula or the Book 5 formula is used, neither of which is mine, by the RAW the ship's fuel tankage MUST be sufficient to handle the maximum jump rating of the Jump Drive. In this case, the Survey Scout would in fact be only capable of travelling three parsecs before requiring fuel. Now, you have said the numbers don't make any sense because a Survey Scout should be able to go long distances before refueling. Based upon what?
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Kirk Andersen
United States
Athens
Tennessee
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The fact that you can always change the fuel capacity of a ship (by maybe shifting the amount of cargo space into fuel capacity space) means that the formula for computing the fuel capacity of a ship during ship design is not inherently wrong I just think that determining fuel usage by the way the books say should be different, that's all.
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Steven Ege
United States
Fall River
Massachusetts
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The RAW does mention that the fuel formula is the minimum, but that isn't why I asked the question I did. What I wanted to know was what book, film, or combination of the two influenced your decision.
I do understand where you are coming from since I have tried it myself. However, Traveller was designed to emulate science-fiction of the '50s and early '60s, before Star Trek changed everything. The setting assumptions in Book 2 and 5 make it difficult to break out of that box without essentially rewriting the entire design system. It's not impossible to do, but in doing it you have to think through the ramifications of the change and what systems it affects.
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Kirk Andersen
United States
Athens
Tennessee
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There is no book or film that influenced me in this. It was the simple fact that the survey vessel (and you admit this) is only able to go three parsecs before it has to refuel convinced me that computing fuel usage should be different. The scout/courier (which is also somewhat of an exploratory vessel),would be able to go six parsecs under my rule. It could only go three parsecs in the book's formula. If you look at the rules for generating subsectors in the scouts book there is a possibility that a subsector could only have a couple of star systems in the entire subsector. You would need a ship to traverse the long distances necessary to get to these systems. Under the official fuel consumption formula you would need a ship with a very large fuel capacity and very small tonnage in order to traverse some very long distances. Personally I don't think such a ship could be made and follow the fuel usage rules detailed in books 2 and 5.
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Art Gorski
United States
Prescott
Arizona
Get my Mac software for Classic Traveller at http://naasirka.weebly.com/
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Or you could use 2 ships, one of which is a large tanker.
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Steven Ege
United States
Fall River
Massachusetts
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There is a specific reason why large Book 2-design vessels aren't capable of high Jump factors. It all boils down to the general setting assumptions of the system. An interesting article (here) speculates that Traveller was based on the Dumarest of Terra series, since most of the Traveller setting assumptions were pulled verbatim or subtly modified from that series. For the Imperial element which appeared in Adventures and Supplements, the other source was the novel "Space Viking". The Dumarest of Terra series is easily the largest influence, and works under the following assumptions:
1. Distances are vast.
2. Travelling on ships to go from planet to planet is difficult, time-consuming and costly.
Traveller takes the ball from Dumarest of Terra and runs with it.
1. Distances are vast.
The smallest possible interstellar distance is one parsec (3.26 light years). Travelling shorter interstellar distances is impossible.
2. Travelling on ships to go from planet to planet is difficult, time-consuming and costly.
Ships are required to travel a minimum of 100 planetary diameters from a world, which takes hours. They then have to engage the Jump Drive, spend a week in Jump, hope they don't misjump, and come out at their destination needing a refuel. Travel is difficult because of the planetary diameters requirement and the possibility of a misjump. It's time-consuming because it requires a week to travel the distance regardless of the rating. It's costly because you have to refuel at the end of every jump (assuming you travel the maximum distance each time) at a cost of Cr500/ton (refined) or Cr100/ton (unrefined).
So there you have the foundations of Traveller space flight. I don't believe anyone here has questioned what you are attempting to do, since it is your game and your rules. It's easy to change rules, but to do so without truly understanding the underlying reasons behind the way things are could lead to unexpected problems in other areas.
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