External collapsible tanks

[McPerth]

I guess it needs not to be insisited about the limitations to jump (or multiple ones) imposed by fuel needs.

To overcome them, several options have been proposed:

Fuel for multiple jumps: the easiest, but also the least usable, as it needs to devote large parts of the volume to fuel. Mostly useful at low TLs, or in ships with low jump capability.

Drop tanks: Being external, they don't use internal volumen, but they need to be mounted at each stop or them make your ship larger, with the performace (in jump and maneuver) reduction that means

Tankers: large ships devoted to carry fuel. They need to be realy enormous, as they need fuel or themselves (twice, if they are to return from where no fuel is available) aside from that carried to distribution. That means that a J3 tanker, needing 60% of the volumen for itself and about 10% more for drives, crew, etc... could only carry about 30% of their volumen as fuel for distribution, and a J4 one could carry less tan 10% of its volume for it (in MT, due to lessened jump fuel requirements, those numbers are different).

Collapsible/dismountable tanks: Devoting part of the hold to fuel, either in a semi-permanent way (dismountable) or in an inflable tank that does not use space when not inflated (collapsible).

My proposal in this thread would be for a mix among drop and collapsible tanks: External collapsible tanks.

Those tanks are as collapsible ones but taken externally, and folded (with an internal wire system) as they empty themselves as fuel is used. The folding mechanism would use some space, though (about 0.5% of their inflated volume).

Advantages:

• Minimal use of space (little more than drop tanks)
• Allow for another jump (as drop tanks)
• Reusable
• Don't increase the size of the ship when folded

Drawbacks

• Being unarmored they are fragile
• Built on light materials, they cannot hold fuel indefinitely (they leak some hydrogen)
• Installing them needs some refitting (as the folded tanks must be adapted)
• When inflated they increase size (as drop tanks)
• When inflated, they make this ship unstreamlined, regardless its true configuration
• They cannot be inflated by skipping (corollary of the former point)

Game use:

• They can be installed at any C+ starport at the expense (in volume) of 0.5% of their inflated volume and at the same cost of drop tanks (Cr 10000+1000 per ton of capacity). Installing them takes a week (but can be done at the same time of annual maintenance).
• When inflated, they function as drop tanks, but they slowly leack fuel, not being able to jump with its fuel after a week of inflating them (assuming their capacity os that of 1 jump)
• Any hit received while they are inflated destroys (1d6-1)x 10% of them, even if the hit produces no other damage (any no effect result)
• When folded, they are considered as internal to the ship, not having any effect (aside from the volume needed, as told above).

Ideas? thoughts?

 

[CliffBates]

I guess it needs not to be insisited about the limitations to jump (or multiple ones) imposed by fuel needs.

To overcome them, several options have been proposed:

Fuel for multiple jumps: the easiest, but also the least usable, as it needs to devote large parts of the volumen to fuel. Mostly useful at low TLs, or in ships with low jump capability.

Drop tanks: Being external, they don't use internal volumen, but they need to be mounted at each stop or them make your ship larger, with the performace (in jump and maneuver) reduction that means

Tankers: large ships devoted to cary fuel. They need to be ruly enormous, as they need fuel or themselves (twice, if they are to return from where no fuel is available) aside from that carried to distribution. That means that a J3 tanker, needing 60% of the volumen for itself and about 10% more for drives, crew, etc... could only carry about 30% of their volumen as fuel for distribution, and a J4 one could carry less tan 10% of its volume for it (in MT, due to lessened jump fuel requirements, those numbers are different).

Collapsible/dismountable tanks: Devoting part of the hold to fuel, either in a semi-permanent way (dismountable) or in an inflable tank that does not use space when not inflated (collapsible).

My proposal in this thread would be for a mix among drop and collapsible tanks: External collapsible tanks.

Those tanks are as collapsible ones but taken extrernally, and folded (with an inernal wire system) as they empty themselves as fuel is used. The folding mechanism would use some space, though (about 0.5% of their infalted volume).

Advantages:

• Minimal use of space (little more than drop tanks)
• Allow for another jump (as drop tanks)
• Reusable
• Don't increase the size of the ship when folded

Drawbacks

• Being unarmored they are fragile
• Built on light materials, they cannot hold fuel indefinitelly (they leack some hydrogen)
• Installing them needs some refitting (as the folded tanks must be adapted)
• When inflated they increase size (as drop tanks)
• When inflated, they make thi ship unstreamlined, regardless its true configuration
• They cannot be inflated by skipping (corolary of the former point)

Game use:

• They can be installed at any C+ starport at the expense (in volume) of 0.5% of their inflated volume and at the same cost of drop tanks (Cr 10000+1000 per ton of capacity). Installing them takes a week (but can be done at the same time of annual maintenance).
• When inflated, they function as drop tanks, but they slowly leack fuel, not being able to jump with its fuel after a week of inflating them (assuming their capacity os that of 1 jump)
• Any hit received while they are inflated destroys (1d6-1)x 10% of them, even if the hit produces no other damage (any no effect result)
• When folded, they are considered as internal to the ship, not having any effect (aside from the volume needed, as told above).

Ideas? thoughts?

Rather interesting. But they need to be jettisoned if the ship enters combat. But for commercial ships they could be a rather useful tool. There needs to be lets say a scoop and filtering system and the bypass to fill these inflatable H-tanks.

 

[McPerth]

Rather interesting. But they need to be jettisoned if the ship enters combat. But for commercial ships they could be a rather useful tool. There needs to be lets say a scoop and filtering system and the bypass to fill these inflatable H-tanks.

Not necessarily jettisoned, just folded (after all they are thought to be inflated just for the jump).

I thought abut filling from the tanks themselves (so with already refined fuel if you have a pruifier plant) while then filling the tanks again (if you do it with unrefied fuel, you have the whole jump time to refine it it).

 

[whartung]

There needs to be some structural element to keep the bolts from being yanked out when you're running around with several 1000 dTons of fuel in baggies.

Basically, some kind of reinforcement at the cables end points, or something.

 

[Lycanorukke]

There needs to be some structural element to keep the bolts from being yanked out when you're running around with several 1000 dTons of fuel in baggies.

Thats what came to my mind.

When the bags are inside the ship (the standard version) they are handled by the inertial comp system. The standard external tank (or drop tank) is a rigid structure bolted to the ship. Bags are on the outside are not handled by the the inertial comp system and lack a rigid structure, so spin your M-drive up and watch the bags rip off or bulge and rupture, with the additional bonus of your ships agility would be reduced to 'drunken cow' level.

And then of course there is the micro-meteor problem as well.

 

[Condottiere]

Zeppelins; or blimps; I think some people do come across this idea to add the minimum ballast required for a transition with a smallcraft.

But it also indicates likely maximum acceleration.

 

[SanDragon]

I don't think the collapsible tanks can be installed outside the hull.

IIRC, they are placed in the cargo hold, which increases your range, but at the expense of, hey, no cargo!

 

[Condottiere]

I'd call it the Blood Eagle Gambit.

 

[warwizard]

I believe that the original specs for the fuel bladders is that they used 10% of the volume in the cargo bay when empty so it might be that you are off by an order of magnitude on the deflated volume.

Next issue is the ship that the bladder mounted on 6g? Can the full bladder hold up to that level (or any level) of acceleration?

The internal fuel bladder has the walls of the cargo bay and internal g-comp fields, perhaps if you built a g-comp for the filled volume of the bladder. (Rules for per M3 per G cost mass power and volume given in the FF&S rules *(TNE and T4) The G-comp rating is the maximum acceleration the ship may sustain when the bladder is full. (varies by TL)

Full bladders are not airframe, but might be made to be streamlined, however they limit speed in atmosphere to low subsonic levels due to lack of a rigid surface high speed airflow will rip open the bladders.

I would have fairing panels that cover the deflated bladder and g-comp equipment to restore streamlining when deflated and this volume of the bladder, g-comp and fairing panels all be counted as part of the internal volume of the ship. These fairing panels may be armored to the same level of armor as the basic hull, providing protection from battle damage the same as the rest of the hull.

 

[mike wightman]

If the technology exists to pump fuel from drop tanks into the jump drive system within the timeframe of jump operation, then what you propose is to make a collapsible 'drop' tank that folds up as the fuel is transferred to the drive or internal tanks.

If such a thing is possible why not just use a fueling station or tender and a really long hose - transfer the fuel during jump prep?

 

[warwizard]

If the technology exists to pump fuel from drop tanks into the jump drive system within the timeframe of jump operation, then what you propose is to make a collapsible 'drop' tank that folds up as the fuel is transferred to the drive or internal tanks.

If such a think is possible why not just use a fueling station or tender and a really long hose - transfer the fuel during jump prep?

Well the tank will have large diameter fuel ports, the really long hose is more like a 2m pipe, (a small motor home is about 5 Dt how many garden hoses does it take to drain it in 30 min?) And how long is this pipe, 200m 500m? So we'd have 20 dt of fuel held in the pipe on a 200 meter one, and the bigger the ship the more pipes or larger pipes you would need, and mis-jump if the pipes used were too small and failed to provide enough fuel flow?

 

[salochin999]

Tankers: large ships devoted to cary fuel. They need to be ruly enormous, as they need fuel or themselves (twice, if they are to return from where no fuel is available) aside from that carried to distribution. That means that a J3 tanker, needing 60% of the volumen for itself and about 10% more for drives, crew, etc... could only carry about 30% of their volumen as fuel for distribution, and a J4 one could carry less tan 10% of its volume for it (in MT, due to lessened jump fuel requirements, those numbers are different).

Given the huge fuel requirements tankers never made much sense to me (so imtu I say fuel purification takes a lot more space and time so it pays to have specialist fuel refiners with a fleet).

However combining the idea of tankers with your external tank idea... how about you have tankers at the jump point and the ship jumping runs a fuel line to the tanker and uses that fuel to create the jump bubble so they still have a full tank on exit.

So a route with a J2 gap could have an orbital refinery around the gas giant and an SDB tanker parked full of fuel 100 diameters away so a Free Trader pays for the fuel for the first J1 and has full tanks for the second J1.

Although to me anyway this would require a change to my visuals of jump - slower and with a first stage where a pre-bubble is formed around the ship followed by ignition so the fuel line could be detached after the pre-bubble is formed.

edit: i see mike wightman already suggested this

 

[mike wightman]

You know what would have made a lot more sense than drop tanks - drop capacitors...

 

[McPerth]

Many good points here, I'll try to answer them...

There needs to be some structural element to keep the bolts from being yanked out when you're running around with several 1000 dTons of fuel in baggies.

Basically, some kind of reinforcement at the cables end points, or something.

(also to all other posts with similar reasoning)

Remember that those bladders are not thought to maneuver with them. Their use is to be filled (probably by fuel shuttles or similar) as close to the jump as posible, just to be used for the jump, and avoid maneuver with them.

And then of course there is the micro-meteor problem as well.

What's the possibility if they are inflated as few time as posible?

I believe that the original specs for the fuel bladders is that they used 10% of the volume in the cargo bay when empty so it might be that you are off by an order of magnitude on the deflated volume.

ITTR that they occupy no volume when not inflated, but I could not find the rules about it, so I may well be wrong. Do you remember where they are?

Full bladders are not airframe, but might be made to be streamlined, however they limit speed in atmosphere to low subsonic levels due to lack of a rigid surface high speed airflow will rip open the bladders.

For gaming reasons, the fragility of the bladders would mean it is not considered streamlining. See also that there's no point to land on a planet with them inflated, and to skip fuel you need a mínimum of speed to aspirate the fuel, so, the effect in game terms is no streamlined while inflated.

I would have fairing panels that cover the deflated bladder and g-comp equipment to restore streamlining when deflated and this volume of the bladder, g-comp and fairing panels all be counted as part of the internal volume of the ship. These fairing panels may be armored to the same level of armor as the basic hull, providing protection from battle damage the same as the rest of the hull.

If I understand you well, that's more or less what I had in mind. Think about a car airbag as the bladder. When not inflated, it's hold in a small, covered compartment (just it infaltes quite slowler tan an airbag and is folded quite more easily, in an automated way)

If the technology exists to pump fuel from drop tanks into the jump drive system within the timeframe of jump operation, then what you propose is to make a collapsible 'drop' tank that folds up as the fuel is transferred to the drive or internal tanks.

If such a thing is possible why not just use a fueling station or tender and a really long hose - transfer the fuel during jump prep?

You need the tender or station to do that, while the bladders can be inflated with fuel shuttles (or any smal lcraft able to skip fuel taht can fill them in a reasonable time).

You know what would have made a lot more sense than drop tanks - drop capacitors...

Capacitors cost (as given in HG description of the BG, page 31) is MCr 4 per ton, each ton holding up to36 EP. A ship requires (as given in the break off description, page 39 CT:HG) two turns worth of EP for a PP rating equal to jump (so, 0.01M*Jn*2). So a free Trader would need 2 EP worth capacitors (at MCr 4/ 36 EP, that would cost about Mcr 0.5, against the Kcr 11 for drop tanks.

This aside, in the BG description (page page 43) is told that the ship needs fuel, aside frm the EPs needed in its capacitors to jump...

See that, as I understand it, fuel is used to produce the energy for the capacitors, and while the energy is hold in them, the drop tanks are released (or the bladdres are fold), then releasing the power to the jump gird to initiate the jump. If what you have is the energy in the capacitors, then you have not time to release them, as the energy is already i nthe jump gird, so initiating the jump as the stored energy is released.

 

[mike wightman]

I should have said - I like the idea by the way.

 

[McPerth]

I should have said - I like the idea by the way.

Glad to hear

 

[McPerth]

I believe that the original specs for the fuel bladders is that they used 10% of the volume in the cargo bay when empty so it might be that you are off by an order of magnitude on the deflated volume.

ITTR that they occupy no volume when not inflated, but I could not find the rules about it, so I may well be wrong. Do you remember where they are?

Found it, in MT RM page 83:

Collapsible Tanks: Large fuel bladders that are istalled in the cargo hold (...) Collapsible tanks cost Cr 35 per kl¹. They take no space when empty

note 1: so about 125 per dton​

So you can see I made them quite more expensive and using volumen to reflect the fact taht they are in fact more robust to be used as external...

 

[warwizard]

TNE FF&S pp. 62
Collapsible Tanks
Insulated fuel bladders may be carried in the cargo hold to carry
additional fuel. This fuel may not be used directly, but must be
pumped into the normal fuel tanks for use. Collapsible tanks cost
Cr100 per cubic meter of fuel capacity, and when empty can be
stored at 5% of their full volume.

so we're both right, and the 10%, I'm thinking is from Bk 2 of CT.

 

[Condottiere]

I do seem to recall one rule that says that you can't use fuel bladders directly as jump fuel, it has to be transferred to the main tanks.

 

[McPerth]

TNE FF&S pp. 62
Collapsible Tanks
Insulated fuel bladders may be carried in the cargo hold to carry
additional fuel. This fuel may not be used directly, but must be
pumped into the normal fuel tanks for use. Collapsible tanks cost
Cr100 per cubic meter of fuel capacity, and when empty can be
stored at 5% of their full volume.

so we're both right, and the 10%, I'm thinking is from Bk 2 of CT.

I didn't find any reference to them in LBB2 (nor in any CT book), what's not to say it des not exist...

Good once more for inter-version coherence :devil:...

I do seem to recall one rule that says that you can't use fuel bladders directly as jump fuel, it has to be transferred to the main tanks.

That's what warwizard's quote says...

in this case, the use would be to inflate the baldder with unrefined fuel, use the refined one in the tanks, pump the unrefined from the bladder to the tanks (I asume this can be done as they are becoming empty, assuming they are divided into comparimentalized ones and pumping can be done quite quick, as the use of drop tanks hints), and jump with full tanks (of unrefined fuel, but with time to refine it) and folded bladder (unlike I explained before).