Different fuel question: transfer times?

[Putraack]

How long does it take to fuel up a starship? Assuming the connections are all standardized, of course.

Not that I'm interested in getting off the station in a hurry or nuthin', I'm just asking. You know, for a friend....

And I'm certainly NOT contemplating pumping out of a freighter that just happened to have its drives shot out. It was like that when I got here, officer, honest! :roll:

I was going to ballpark-guess at 1 ton per minute? Plus a minute or so to make connections? Maybe longer without automation, or in zero-G?

 

[far-trader]

Well... the real world KC-135 (midair refuelling tanker) does about 1500 gallons per minute, works out to about 5600 litres per minute, figures around 4dtons per 10 minutes in handy even figures.

Midair refueling is not something to dawdle over so the transfer rate is probably good. However it is a smallish hose and the planes drinking aren't handling that much fuel. I think for traveller you could get away with something faster. For ease of play (and recall) without pushing things too far... maybe 1dton per minute?

...for a dedicated fuelling operation

Now, something like fuel transfers from a dead ship to another ship, if you ever had to engage in such are not going to be routine, safe, or quick. If you could do it at all.

You'd need extra gear not part of the standard kit aboard most ships before you could even think about doing it.

 

[far-trader]

A bit further pondering...

...the above is probably going to be true(ish) for smaller ships (say up to 1000tons?). Larger ships are going to have bigger handling challenges and different fittings so they don't have to take a month to fill up

In general I think routine filling for any size ship is likely to take no more than an hour. So the specifics of the type of service and fittings is going to vary with the size of the ship and its fuel requirements. Probably. Maybe...

Or you can always resort to a Speed of Plot meme. If the players need to be delayed for 3 hours to allow the nemisis time to arrive then that is how long it takes to complete the fuelling

 

[Putraack]

Now, something like fuel transfers from a dead ship to another ship, if you ever had to engage in such are not going to be routine, safe, or quick. If you could do it at all.

You'd need extra gear not part of the standard kit aboard most ships before you could even think about doing it.

That's something I'd not initially thought of: assuming ships have "receiving" gear, while a station would have "transmission" gear, the ship trying to siphon gas out would need some kind of special gear.

I'm getting set to run "Pirates of Drinax" and I noted that their pirate-ship-to-be has enough fuel for one jump at a time. So, if it were going to heist something, they'd better do it AFTER fueling up, lest they get stuck in-system when the heat arrives. Or else pump it out of the prey, thus my question.

I'll give bonus points if a player that figures this out in time, but I think I'd better point it out before it all goes bad on their first hit.

 

[Easterner]

Tractor trailers have saddle tanks and can when available fill two tanks at once. So it is likely that ships at A&B and busy C ports can fill multi-tanks/have numerous fueling points so can do all at one time. Ocean refueling from internal hoses likely slower, diving and filling like submarine ballast tanks is probably an option in safe water i.e. no known tentacle creatures.

 

[phavoc]

Loading a supertanker 1,000 feet long, using three flexible 16ind diameter pipes (each one pumps 75,000 barrels of oil per hour) means it takes about 9-10hrs to fully load a tanker, under perfect conditions.

For the space shuttle main LH2 tank (390,000 gallons worth) it takes 3 hrs to fill completely. There are 3 17" lines running into the tank for fueling. The tank itself is 29.5m long and 8.4m in diameter, and it holds about 53,000 cubic feet of liquified hydrogen.

I think the shuttle example is closer to what you are looking for.

 

[Hopeless]

So the fuel transfer time should ultimately be related to the speed of plot? 8)

 

[Captain Jonah]

This would be with purpose built re-fuelling systems, armoured pipes etc. The shuttle example given early is a bit over 100Dtons of fuel or 33Dtons per hour or 10Dtons per hour per fuel pipe.

Normal civilian ships are not necessarily going to be designed for high speed refuelling where as military ships probably are. So a civilian ship maybe about six hours and a war ship three. This would give you a number of refuelling points to the fuel tanks to allow this many fuel pipes to connect at once. A Free trader with a whole 22Dtons of fuel would have a single refuelling connector. A far trader also would have one meaning its refuel would be five hours.

A subby would also have one where as a Lab ship with 88Dtons of fuel would have two points.

A Gazelle with 176Dtons of fuel would have 4 points.

So rough rule of thumb. One refuelling point (10Dtons per hour) per 200Dtons on a civilian ship and double that on a military ship. So a Patrol cruiser can take on 40Dtons per hour, a Liner 30Dtons per hour.

Any ship is going to have on board hoses and pipes in its maintenance and repair stores plus 3d Fabricators to make fittings. However pumping liquid H is not something you do fast using make shift piping. So half or a quarter the rate of fuel transfer. The ship itself will have onboard fuel pumps since I presume ships can transfer fuel between tanks and any ship with scoops and purifiers is able to move fuel around.

Call it half speed with an engineering (jump or power) roll or quarter speed safely with no roll.

Example A far trader can safely transfer 10Dtons per 4 hours from a wreck or in two hours with an Engineer roll (level determined by situation).

 

[F33D]

A simple rule may be 2 hours*Jn for civilian. 1/2 that for military.

 

[Hopeless]

Would the skill of the engineer(s) play a part in how long that might take?

For example it needs say 4 people to supervise and insure the refuelling is properly done whilst the better trained engineers could cut time on this through experience and perhaps covering themselves by adding a few more precautions to the procedure such as having the pipeline linking the two ships in the case of the wreck having a few extra safeties so if something goes critical somewhere along that pipeline it can be shut down without say for example the fuel blowing up and spreading back to their ship before they can do anything about it?

I wonder would it make sense to have say the equivalent of extra barrels of fuel aboard as emergency supplies?

Its just that if speed is of necessity is there anyway to collect such fuel in cargo pods or whatever so they can be used to refuel the ship whilst its heading back out dropping off these now emptied pods at a convenient marker in the outer system so they can be picked up and returned for the next ship that needs to be refuelled urgently?

 

[locarno24]

Its just that if speed is of necessity is there anyway to collect such fuel in cargo pods or whatever so they can be used to refuel the ship whilst its heading back out dropping off these now emptied pods at a convenient marker in the outer system so they can be picked up and returned for the next ship that needs to be refuelled urgently?

High Guard includes Drop Tanks. These are principally used for military strike ships (to allow them to carry fuel for particularly long jumps without impeding combat volume), but there's nothing preventing you jumping without blowing the tanks - making them detatchable tankage.

Well... the real world KC-135 (midair refuelling tanker) does about 1500 gallons per minute, works out to about 5600 litres per minute, figures around 4dtons per 10 minutes in handy even figures.

May be relevant for Pirates of Drinax style interception and grab everything attacks.

So about 2 dTons per combat round if the equipment on the other ship is co-operating. As noted, I'd make that 'per 100 dTons volume of the smaller ship' - that defining the limiting number of pumps/ports.

If you're salvaging from a ship without working pumps, then assume you've got to cut your way into the tank and set up a safe feed first, which is going to take too long to be done in combat.

 

[Captain Jonah]

You can carry extra fuel in demountable or collapsible tanks in cargo. Demountables are directly plumbed in and can be used as is. Collapsible tanks are fuel bladders that cannot stand the strain of directly providing fuel to the drives and so must be pumped into the main tanks before use.

Collapsible ones then collapse down to 1Dton per 20Dtons of fuel. Handy for double jumps but a bit fragile. Demountable ones are hard tanks that need a star port or bay to remove.

A space combat turn is what, 6 minutes.

How about 1 Dton per space combat turn at maximum rate. That is 10Dtons per fuelling point per hour. The Drinax harrier as a warship would have two connectors and could then transfer 20Dtons per hour.

Add an Engineer + INT, 1 space combat turn, 8+ roll to double the rate of fuel transfer for that turn but on a failure by 2+ negative effects the ship suffers a fuel breach losing that turns fuel into space and on a disaster 4+ negative effects takes a hit on the damage table (internal or external depending on how mean the ref is :wink: )

In terms of the “Donor” ship not having power. You can dock and provide it with power through the power/life support connections in the docking clamp if your engineer is any good. These being the ones that allow you to take air and power from a station when docked and powered down.

Or go with a tug, high G drives and clamps. Disable the victim, grab them and run off.

Hide in the black and pick them clean at your leisure. If you are going to do pirating do it properly :twisted:

 

[AndrewW]

Collapsible ones then collapse down to 1Dton per 20Dtons of fuel. Handy for double jumps but a bit fragile. Demountable ones are hard tanks that need a star port or bay to remove.

Collapsible ones take up 1% of the full tonnage when empty.

 

[phavoc]

Would the skill of the engineer(s) play a part in how long that might take?

For example it needs say 4 people to supervise and insure the refuelling is properly done whilst the better trained engineers could cut time on this through experience and perhaps covering themselves by adding a few more precautions to the procedure such as having the pipeline linking the two ships in the case of the wreck having a few extra safeties so if something goes critical somewhere along that pipeline it can be shut down without say for example the fuel blowing up and spreading back to their ship before they can do anything about it?

For the most part, fuel is pumped at the safest, fastest speed possible when it comes to anything big. The piping, valves and pumps are all designed to operate at the highest capacity. You really don't want your fuel lines rupturing inside of the ship and spewing liquid hydrogen. So I'd say the speed of pumping that was presented earlier is the maximum "safe" speed. Sure, your engineer could add more power to the pump to get the flow rate up, but then you would need to determine if there was a system failure, and where would it occur? Most likely from the fuel entry point(s) on the ship to the fuel tank. The fuel lines to the reactor and jump drive could be shut off, but that might blow a valve through overpressure. I'd just make a table of mishaps and roll against it.

As far as pumping fuel from a wreck, there's the risk of a line blowing in space, but I'd think the most risky part would be when you attach your hose to their tank and find out that the safety valves are shut and you have to manually open them by going inside the ship (or something similar). Then you get to have fun, err, "encounters" with the PC's.

I wonder would it make sense to have say the equivalent of extra barrels of fuel aboard as emergency supplies?

Its just that if speed is of necessity is there anyway to collect such fuel in cargo pods or whatever so they can be used to refuel the ship whilst its heading back out dropping off these now emptied pods at a convenient marker in the outer system so they can be picked up and returned for the next ship that needs to be refuelled urgently?

The rules already mention inflatable tanks. I can see where it might be useful to carry a week or more worth of power plant fuel if you expect to spend a lot of time in a system. Easiest way to handle that is just create a standardized container that stores hydrogen and just park it away in your cargo hold. You can tap it when needed (or, perhaps, a leaky valve vents enough hydrogen where it ignites and blows a hole in the ship...oops).

 

[Putraack]

I'm liking all of this, thanks! Especially Captain Jonah.

Regarding dragging the target off into the black, that's something I was thinking would need to happen. But I'm the referee, I'd much rather the players think of that on their own. I don't see towing clamps in the Core RB, are they somewhere else?

 

[Captain Jonah]

High guard, starting on page 45 at the bottom of the second block of text.

 

[Putraack]

Nuts, I haven't gotten HG for this edition yet, still only have CT.

 

[phavoc]

Here's the section on docking clamps (see below). You can pick up the pdf off DrivethruRPG pretty cheap. It's not necessary if you stick with smaller ships, but its nice to be able to reference additional systems and equipment to integrate with what's listed in the Core book.

Docking Clamp: A docking clamp allows a spacecraft to carry a small craft or other vessel on the outside of the hull. Recalculate the ship’s Thrust Number by adding the tonnage of the spacecraft and the docked craft together, round up to the nearest hull size, then
compare that to the thrust by drive volume table. If performance is reduced to the point that it has no rating, then treat the ship as if it has the equivalent of a solar sail. Jump performance is reduced in a similar manner, but reductions below 1 mean the drive cannot function.

For example, a 200–ton vessel has a docking clamp. Attached to the
clamp is a 50–ton cutter. Together, the vessels have a displacement
tonnage of 250, which is rounded up to 300. The 200–ship has M–Drive
B, which gives the combined spacecraft a Thrust of 1. When the cutter
disconnects from the clamp, the 200–tonner will be back at its normal
thrust of 2.

The size of the vessel that can be clamped depends on the size of the docking clamp.
Clamp Tonnage Attached Ship Maximum Cost
1 10–30 MCr 0.5
5 40–90 MCr 1.0
10 100–300 MCr 2.0
20 400–2,000 MCr 4.0
50 2,000+ MCr 8.0

 

[Putraack]

Thank you. I've moved it up my "to-get" list.

 

[Mithras]

On a related note i.e. accidents ..... what are the properties of liquid hydrogen (presumably cryogenically contained ... under pressure??).

In one game I ran I had it leak into the cargo hold... but would it turn into frozen gas? Would it still be a liquid? What would happen if 20 tons of LH leaked into the hold, or out of a disconnected hose???? Fire?