MgT HG 2e Special Fuel Tanks (Collapsible, Demountable, Drop Tanks)

[Condottiere]

While the Trillion Credit Squadron isn't essential, and can be a little inconsistent, it has useful information if you're interested in starship construction, reconstruction, and fleet maintenance.

 

[snrdg121408]

Hello Condottuere,

While the Trillion Credit Squadron isn't essential, and can be a little inconsistent, it has useful information if you're interested in starship construction, reconstruction, and fleet maintenance.

To be honest I have found many Traveller and other game rule sets to have material like Trillion Credit Squadron that are not essential and are a little inconsistent. I also feel that the other rule sets has useful information that, when interested or trying to fill in a blank area can be helpful.

 

[steve98052]

A type of fuel tank feature I'd like to see is an easy-convert fuel tank:
- Like a collapsible tank, it can be stowed to allow most of its space to be used for cargo.
- But like a demountable tank, it can be used directly as jump fuel, rather than requiring a pumping from a collapsible tank into main tanks before jump.

A ship with both a drop tank fixture and an external cargo cradle would partially satisfy such a feature's goals:
- It would be easy to switch between extra fuel and cargo.
- It could be used directly for jump fuel.
However, the item not currently in use – drop tank or external cargo hold – would have to be stored somewhere other than aboard the ship. It would also be fragile.

The latter complaint could be satisfied by making it a module like the ones that can be used in a modular cutter. But it would still require storage somewhere other than aboard the ship.

Can anyone think of a way within the rules to build a ship with space that could be converted between extra fuel space and extra cargo space, and still have the extra fuel space usable directly for jump without a separate pumping operation?

By the way, the only situation where such a feature would really be useful would be a ship that's built with a higher-jump drive than it usually uses. For example, a Far Trader that can haul an extra 20 dtons (or even 18 dtons) of cargo when it's making a Jump-1 instead of its maximum of Jump-2, or a ship that's capable of Jump-3 when it needs it, even though it usually does only Jump-2. Otherwise, the pumping operation required for a collapsible tank isn't really a big deal; the only problem there is that the collapsible tank is comparatively fragile, which can be resolved by including a partition between the cargo space where the collapsible tank can be used and the rest of the cargo hold.

- - -

As an aside, I don't imagine collapsible tanks as bladders. Instead, I imagine them as a set of solid panels that convert cargo hold space into fuel cryo-tanks, except that they're designed to be easy to dismantle into something that can be stowed in a much smaller space.

I would also imagine that they're specific to a given cargo hold configuration, so you couldn't use one built for a Free Trader in a Subsidized Trader even if the sizes were useful. For example, a Free Trader gets Jump-1 jumps out of 40 dtons of collapsible tanks, and a Subsidized Trader gets one Jump-1 out of 40 dtons of fuel, but you wouldn't be able to use the same 40 dton collapsible tank in both ships. You couldn't even use them in different models of the same ship; for example if there was an alternate model Free Trader with a taller but narrower cargo deck, it would need its own model of collapsible tank.

 

[phavoc]

For any ship carrying fuel as cargo, say a free trader looking to bridge a J3 rift, it's best to simply carry water, then run it through your on board processors to convery and fill your tanks.

Since your jump fuel is consumed at the start of your voyage you can pump the water and convert it all prior to exiting jump space, so your downtime is minimal while you plot your next jump. And it's about as low of a hazard you can get onboard a ship.

 

[Imeanunoharm]

A type of fuel tank feature I'd like to see is an easy-convert fuel tank:
- Like a collapsible tank, it can be stowed to allow most of its space to be used for cargo.
- But like a demountable tank, it can be used directly as jump fuel, rather than requiring a pumping from a collapsible tank into main tanks before jump.

A ship with both a drop tank fixture and an external cargo cradle would partially satisfy such a feature's goals:
- It would be easy to switch between extra fuel and cargo.
- It could be used directly for jump fuel.
However, the item not currently in use – drop tank or external cargo hold – would have to be stored somewhere other than aboard the ship. It would also be fragile.

The latter complaint could be satisfied by making it a module like the ones that can be used in a modular cutter. But it would still require storage somewhere other than aboard the ship.

Can anyone think of a way within the rules to build a ship with space that could be converted between extra fuel space and extra cargo space, and still have the extra fuel space usable directly for jump without a separate pumping operation?

By the way, the only situation where such a feature would really be useful would be a ship that's built with a higher-jump drive than it usually uses. For example, a Far Trader that can haul an extra 20 dtons (or even 18 dtons) of cargo when it's making a Jump-1 instead of its maximum of Jump-2, or a ship that's capable of Jump-3 when it needs it, even though it usually does only Jump-2. Otherwise, the pumping operation required for a collapsible tank isn't really a big deal; the only problem there is that the collapsible tank is comparatively fragile, which can be resolved by including a partition between the cargo space where the collapsible tank can be used and the rest of the cargo hold.

- - -

As an aside, I don't imagine collapsible tanks as bladders. Instead, I imagine them as a set of solid panels that convert cargo hold space into fuel cryo-tanks, except that they're designed to be easy to dismantle into something that can be stowed in a much smaller space.

I would also imagine that they're specific to a given cargo hold configuration, so you couldn't use one built for a Free Trader in a Subsidized Trader even if the sizes were useful. For example, a Free Trader gets Jump-1 jumps out of 40 dtons of collapsible tanks, and a Subsidized Trader gets one Jump-1 out of 40 dtons of fuel, but you wouldn't be able to use the same 40 dton collapsible tank in both ships. You couldn't even use them in different models of the same ship; for example if there was an alternate model Free Trader with a taller but narrower cargo deck, it would need its own model of collapsible tank.

I wrote a treatise on Cargo hold fuel tanks some time back (late 2013). I may or may not have been drinking, but in it I did make some rules for collapsible fuel tanks. If I rewrote it, I'd probably dot point it, or arrange it a little differently to make it clearer/less wordy. I sent it into to Mongoose, but didn't hear back, (probably due to the afore mentioned reasons )


Cargo Hold Fuel: Containers, Collapsible Bladders and Collapsible Tanks.
For some spacecraft on certain routes or missions it may be economical, expedient or indeed absolutely necessary to carry extra internalised fuel in their cargo holds.

Specialised fuel containers (TL-8) come in standard 10, 20, 50, and 100 dTon sizes (with multiples of 100 thereafter) and can carry the equivalent volume of fuel (The empty Mass is calculated 5% of the total, but the shell is considered thin enough in proportion to ignore). Cost is 0.1 MCr per dTon. Pump rates and requirements* are the same as bladders. They are not collapsible, but that does not mean that they cannot be jettisoned.

Bladders and tanks are both collapsible and take up 10% of their total deployed fuel capacity in d-tons (i.e. a deployed 50 dTon tank takes up 55 dTons of cargo space). The transition from collapsed to deployed, and vice versa, takes 4 + 2d6 rounds. For each technology level advancement above the initial one, this time is reduced by one round (minimum two rounds). Due to their structural rigidity requirements the folding framework cannot be partially deployed. They cannot exceed the size of the ships main tanks due to difficulties maintaining pressure differentials throughout the ship.

Reliable fuel bladders become available at TL-11. They cost 0.5 MCr per undeployed dTon. Fuel bladders are reserve tanks and cannot be used for a jump. Fuel must be pumped into the main tanks for that purpose, making a minimum one dTon fuel pump necessary*. Each pump can empty and fill tanks at 20 dTons of fuel every round, however if the craft is fitted with fuel processors those pumps can be used at an equivalent rate, though processing must cease while the taps are switched.

Collapsible Fuel Tanks (CFT) are available at TL-13 and cost 1 MCr per undeployed dTon. The fuel carried can be used for a jump with the following pump caveats. If the spacecraft has drop tank fittings of a large enough capacity (i.e. two tons per 50 tons fuel), the injectors in these can be co-opted for use with the CFT's, however without drop tank fittings, pumps must be added at one dTon per 50 dTon tank capacity (collars and mounts are not needed). Therefore, drop tanks and internal collapsible tanks cannot be used in the same jump without drop tank fittings and pumps*. Fuel processor pumps are not fast enough and cannot be used, however a standard filling pump is incorporated (see Bladders).

Hits on cargo holds have a percentage chance of damaging the tanks equal to the proportion of space taken in the hold. Note that leaked fuel may be very damaging to other items stored in the hold before it leaks into space.

*At TL-13 pumps are incorporated into the design of containers and bladders. At TL-15 CFT's do not need additional pumps to run drop and collapsible tanks at the same time. Note that in general most designs find it more expedient and flexible to dual purpose the other pump systems.

 

[Condottiere]

Carrying liquids isn't a problem; transferring them over to the tanks directly connected to the jump drive isn't much of one either.

But using the fuel directly from these containers is another kettle of fish.