Versatile Fuel/Cargo

[kevinknight]

I don't know if this has been addressed; if so I haven't found it, but is it possible to make a ship with it's fuel tankage having the ability of being used as cargo hold space? on a permanent basis (ie, not using drop tanks, demountable tanks, etc.)?
Say for example you have a 400 ton merchant. You put a jump 3 drive in it with the 120t of fuel but sometimes you only want to go a jump 1... you've basically got 80t of wasted space.
The idea I came up with is to modularise the fuel tankage so in this case you would have 3 40t internal fuel modules. If you only want to do a jump 1 you only fill up 1 module with fuel, leaving the other 2 40t modules to store cargo in. Since I'm sure you would need extra room for pumps, sealed doors, etc. you could impose a 10% tonnage premium and a cost of 10k per ton. In this instance each module would take up 44 tons and cost MCr0.44 and be able to carry either 40 tons of cargo or 40 tons of fuel.
Thoughts?

 

[-Daniel-]

I would imagine the best way to do this is design some of the fuel to take advantage of the collapsible fuel bladders and then store them when not needed thus opening the space for cargo. I don't think I would make the fuel tanks all ridged then try to drain and reuse the space.

 

[kevinknight]

I would imagine the best way to do this is design some of the fuel to take advantage of the collapsible fuel bladders and then store them when not needed thus opening the space for cargo. I don't think I would make the fuel tanks all ridged then try to drain and reuse the space.

The problem with Collapsible Fuel Tanks is this... Fuel cannot be pumped directly from these tanks to the jump drive, and so a ship must complete a jump before it can use fuel stored in collapsible tanks. Pg. 36 High Guard
Defeats the purpose of having a Jump-3 Drive unfortunately

 

[phavoc]

It's possible, but yu would probably pay a higher penalty, say 20 to 25% of lost tonnage to support your additional internal Lhyd tanks. Remember the is liquid hydrogen we are talking about, so you have to store it in a proper tank, you need cooling and insulation, and you need high speed pumps and vacuums to move it rapidly when you are jumping.

Now, if you were wanting to say take a jump 1 freighter and move it 3 jumps away without refueling, you could simply take on water ad cargo, and at the end of each jump 1 pump water into your tanks and refine (or not) and then jump again. Water itself requires no special issue and simple hoses suffice to pump it.

 

[Condottiere]

Jump drive physics are unforgiving, and I suspect, intentionally worded to prevent this.

 

[AnotherDilbert]

By RAW we cannot do that. And I kind of like it that way, it is one of the main barriers for eating the cake and still having it when it comes to ship design.

There is plenty of flexibility with drop tanks, demountable tanks, and collapsible tanks.

 

[PsiTraveller]

The loss of useful space to fuel is the main reason behind my (blatant product plug) Jump Station Echo module available on TAS. You are quite right in pointing out that unused fuel tonnage is not available for cargo usage and is dead space not being used.

You have a couple of options to improve on things.
1: Go to Drop Tanks and remove fuel tanks entirely, you can leave in Jump 1 fuel for a safety margin if you want. Then simply use fuel as needed.
2: Design the ship and use the fuel module from the Modular Cutter. They are designed to be used as fuel tanks anyway. They are not in your tonnage range that you mentioned, but are canon, so are a good starting point. You can argue that the modular storage space has connectors built in to act as fuel hoses.

3: Decide what you are trying to move, and what risk you want to take doing it and redesign your ship completely. Does your cargo or fuel need to be internal? Will you be in combat? If not go to external cargo mounts are awesome for increasing profits on a ship. A 200 Ton ship with 200 Tons of External cargo mounts with 120 tons of Fuel in Demountable External Tanks is 400 tons J3 fuel and 80 Tons of cargo attached to a 200 Ton J3 ship @400 tons. (an example of this kind of ship is in Jump Station Echo (2nd plug!)). When you are not hauling or Jumping 3 you can load 40 tons of fuel modules onto the External cargo mounts and 160 tons of cargo and Jump 1. Reducing the tonnage allowed from 80 tons to a lower number and asking to armour up the tanks might be an option while allowing load flexibility.

If you want everything internal and protected then you are looking at modular components to a ship as your best bet.

I did a Tricked out Far Trader as a J2 example in this thread http://forum.mongoosepublishing.com/viewtopic.php?f=89&t=119289&p=904491&hilit=tricked+out#p904491

hope this helps

 

[kevinknight]

If you want everything internal and protected then you are looking at modular components to a ship as your best bet.

hope this helps

Actually it did... everything needs to be internal, btw

using the 30t modules from a modular cutter are actually better than paying the 10% tonnage premium I had suggested

the demountable tanks are a bit confusing... why are they so cheap? why do they not require any extra tonnage for hoses, pumps, etc.? and why on earth do they take 4 weeks (apparently regardless of size) to install or uninstall?

 

[PsiTraveller]

I am not sure as to pricing. I think they are very cost efficient myself. (Don't complain! someone might notice how good they are) As for the time it takes to install, I think it is supposed to represent the task of running a liquid hydrogen capable line through a starship cargo bay into a Jump Engine without offering all sorts of instant critical, ship killing accidents.

For internal components then you need to look at Drop Tanks as your fuel supply. Keep 40 tons Jump fuel internal as a safety, and get a Drop Tank collar for the max tonnage you might ever need, which might be 1200 tons if I did the math right. (30 tons of Jump Engine for 400 Tons J3) divided by 2.5% j1 number = 1200 total tons possible to move at J1.

This means 120 tons of fuel Drop Tank collar. (Which is the same as J3, but always think of ways to make extra cash at J1.

 

[AnotherDilbert]

Collapsible tanks have one great advantage, you take them with you.

If you use modules or drop tanks (and drop them), you need more modules or drop tanks to get back to J-3 performance. That is a problem for a lone free trader. For a major shipping line doing scheduled run it should be fairly easy to have replacements handy when needed.

 

[PsiTraveller]

Collapsible tanks are excellent, and if used for water storage they allow a ship to carry a lot of fuel safely and easily. The magic of the fuel processor allows one ton of H2O to be turned into one ton of refined fuel, so the collapsible tank does not need to be cryonic anymore, just a big waterbed bag. Taking fuel along with you is now as easy as tanking cargo units of water in the cargo hold. These can be emptied into the fuel tank to refill it.

The weak point for a collapsible tank is that it cannot be used to power a Jump. The fuel has to be pumped into a fuel tank first. So some J3 compliant fuel tank is needed when you want J3.