Fuel consumption

[JAFARR]

Per Book 2:
At a minimum, ship fuel tankage must equal O.lMJn+lOPn, where M is the tonnage of the ship, Jn is the ship's jump number, and Pn is the ship's power plant rating. Power plant fuel under the formula (10Pn) allows routine operations and maneuver for four weeks. Jump fuel under the formula (O.1MJn) allows one jump of the stated level. Ships performing jumps less than their maximum capacity consume fuel at a lower level based on the jump number used.

In real life, what vehicle actually does consume fuel at the manufacturer’s stated rate? None that I have ever owned. Do all vehicles of the same model get the same fuel consumption? And what happens to fuel consumption as a vehicle is used? However, in Traveller ship design rules, we are given the consumption guide above. In order for this rule to work and the ships designed with it to always succeed in making a jump of the specified distance, we should then conclude that this is a worse case situation. If that is the case, then can we take advantage of a “best case” or even a “normal case” situation to save on fuel costs? If so, how?

Again borrowing from real life, I would suggest that we can make 2 assumptions. (1) All vehicles have a variance in fuel consumption from the design, and (2) this actual consumption increases with time after overhaul. An extension of these assumptions is that the base fuel consumption will vary from overhaul to overhaul. The big question is, “Is there enough variance to be worth the extra record keeping?”

[beeber]

unless the last powerplant etc. maintenance is way overdue, i'd say no, it's not worth the effort in record keeping. unless we want to stat all powerplants & drives to be "AU/kiloliter" or whatever, then add in "mileage" degradation tables. . . . O.o

[robject]

What he said, but, for a player's starship, a variation can add some interesting color.

[Zutroi]

Hmmmmm - as a problem for an engineer PC to solve, seriously out-of-spec fuel use could be a useful adventure handle, particularly out in a frontier environment without access to 'proper' diagnostic/repair facilities...

[rancke]

The plausible way to do it would be to say that power plant fuel was negligible, belowe the resolution of the ship design system, and filled up once a year during the annual maintenance.


Hans

[Swiftbrook]

DM: "OK, let's see" (rolls dice) "Your jump drive is not quite working up to peak performance." (rolls dice) "It just used 110% of normal fuel for that jump. Oh, um, you don't have that much. Um, so you jump drive just used up all your fuel, but you it didn't produce enougth energy to jump, sorry. You're power plant is now shutting down due to a lack of fuel. What do you do now?"

:-)

Too much of a headeach to worry about.

-Swiftbrook

[robject]

Originally Posted by Swiftbrook

DM: "OK, let's see" (rolls dice) "Your jump drive is not quite working up to peak performance." (rolls dice) "It just used 110% of normal fuel for that jump. Oh, um, you don't have that much. Um, so you jump drive just used up all your fuel, but you it didn't produce enougth energy to jump, sorry. You're power plant is now shutting down due to a lack of fuel. What do you do now?"

:-)

Too much of a headeach to worry about.

-Swiftbrook

Definitely don't want to do it that way. Random per jump won't work, as you say.

Instead, do it like Foodrunner or Adventure 3 did it: due to malfunction or poorly maintained hardware, your ship requires 110% j-fuel to jump; the ship has demountable fuel tanks installed in cargo space to increase fuel supply, or perhaps can only make Jump-1 instead of Jump-2 until something changes. Or, alternately, you've got a rare hand-built Droyne model that only needs 90% fuel.

[JAFARR]

robject is more in line with what I had in mind. In a slightly different context, the US Navy once had a class on destroyers rated at 36 knots. That means you should be able to expect all ships of that class to perform within a knot or 2 of that standard. There was one, however, that did 45 knots. It was sent to the shipyards for disassembly and inspection to see why. Nothing any different from specs was found and it was re-assembled. Then it only did 41 knots. The people in charge decided to keep it as it was and not do any more inspections.

Now what I had in mind was a roll at inital trials to establish actual consumption. Lets say the rules are a worse case statement and most ships actually consume 95% of stated consumption. Roll D6. 1 = 100%. 2 through 5 =95%. 6= reroll D6. 1 through 5 = say 93%. 6 = 90%. Now after each annual mantaince recheck consumption. Roll D6 1 = 100% 2 through 5 = inital established consumption. 6 = D6/2 less than inital established consumption.

What does this work out to in fuel savings? Take a 200 ton J2 ship. Worse case is 40 tons of fuel per jump (2 Weeks) 2-5 = 38 tons or 2 ton savings per jump times 25 jumps a year @ a jump every 2 weeks with a 2 week overhaul = 50 tons of fuel a year. If the inital roll was a 6 the the savings will be at least 70 tons with shot at 100 tons a year.

Note that a best case inital roll (6 & 6) followed by a best case roll after (6 & 6) overhaul saves a whopping 127 tons for that year. The numbers are the same for a 400 ton J1 ship.

[JAFARR]

Or having that extra fuel in the tank for a power plant 2 ship works out to several extra days of power plant fuel in an emergency. 10 * 2 = 40 tons of fuel for 28 days or 1.43 tons per day for a LBB2 power plant 2. That is 1.4 extra days power plant fuel for a 200 ton J2 P2 ship that acually uses 95% of the stated consumption rate.

[Madarin Dude]

Well I would think there are different standards. If your ship was in Combat you woudl use more those fusion guns and lasers require a few extra kilowatts. But if you are in survival mode and the ship temp is just above freezing and using only green lights you might be able to stretch it out a bit.