Fuel/Cargo Containers from Deep Space Exploration book

M J Dougherty said:
The intent with these tank/holds was to permit ships operating in a sparse region or intending to cross between mains from time to time to be able to do it and retain most of their cargo capability when making shorter trips.
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The wasted fuel tankage is one of the great limiters of the Traveller ship design system, once you relax the conditions you get major consequences.


Commercial ships will greatly appreciate added flexibility. Trade routes do not always facilitate max jumps, e.g. the Rhylanor - Mora route is 10 Pc, at J-3 that is at least 4 jumps, some of which will be less than J-3. So, while commercial ships will strive to jump as far as possible, that is not always practical, and the added cargo space will probably be economical.


Warships are the most tightly packed, hence the most limited by the fuel, hence have the most to gain by relaxed fuel conditions.
 
Exactly AnotherDIlbert. When the route mandates things a J3 ship will have to Jump J1 or J2 to get to the system it needs to get to. This is the opportunity to move additional cargo. The stellar geography does not always allow a Jump Engine to work at its maximum.

Baithammer: I love external cargo mounts and Jump Nets. I think it is an area where players are well advised to put in aditional Jump engines and cargo mounts and Jump Nets to increase profit capacity when trading. I have written a couple of TAS modules dealing with exactly this. Seed of Doubt and Jump Station Echo. The Jump Station module describes a Drop Tank based trading system where the drop tank fuel savings increases cargo capacity using external cargo mounts. (end blatant plug)

I don't understand what you mean regarding drop tanks. I think drop tanks are an excellent way to move ships across distances.
In a long endurance ship a drop tank serves very well to increase profitability. The drop tank enabled ship increases cargo capacity by whatever percentage of fuel tank you convert to cargo. E.g. a 1000 ton J4 cargo ship would normally need 400 tons of fuel for jump. If you left in a J1 reserve in case of misjump and installed a drop tank collar you could increase cargo by almost 30 percent (minus the drop tank collar tonnage). That is an extra 2 million Credits per Jump along a J4 route.
 
It gives the commander options.

The same could be said for drop tanks.

This is the sort of thing military staffs have to figure out how to optimally employ.

My take on it is that the Imperium Navy is rich enough and large enough not to need the capability. Individual ships and/or classes might have it, for specific missions or deployments.
 
I'm redesigning and comparing some iconic ships, trades mostly. Looking at their original floorplan and options I notice a few things.

A F/C hold is either holding cargo or it holds fuel. You can't fill halfway and use the rest for the other. Those F/Cs are going to be dedicated to holding a specific amount such as a second jump or refueling other vessels. This isn't too much a problem and what the concept was all about, cluster jumping. Once on the other side, you go back to cargo hauling but still, it's either or. Oh, you may need to also carry an extra week of Power Plant fuel since you will be making double jumps.

Cargo holds are often also passageways to get to other ship areas. That could be a problem if you now make the hold F/C. You may need to partition some of the hold as F/C and the rest normal with open space to access other areas. There could be more than one partition to fit the design.

The Free Trader has huge cargo doors and a cargo crane to move large pallets and even larger containers into position. What kind of sealable openings do the F/C containment areas have give unrestricted access for cargo storage especially for those ceiling cranes while safely sealing off that large supply of liquid hydrogen?
 
A F/C hold is not necessary for fuel for a second jump, Collapsible Tanks are better for that. Extra PP fuel can also be carried in Collapsible Tanks.

F/C holds are only necessary to make the primary jump fuel flexible.

Hence F/C holds does not help crossing rifts, they only help to carry more cargo when making shorter than maximum jumps. A primary candidate for F/C holds would be the Subsidised Liner, and perhaps Corsair and Patrol Corvette.
 
You want a reasonable payload to shift across a rift.

When I dealt with it, the optimized jump performance I came up with was factor three and sixty percent tanks.

But drop tanks would allow anything from factor three to six without touching the organic bunkerage, with enough fuel onboard to correct for misjumps.
 
It's optimal; of course, you're parsecage may vary. It's a compromise of time, space and redundancy.

The higher factorized your jump route, the more complex the calculations; also, a technological level twelve piece of equipment should be easier to repair by the indigenes, or at least, source from their manufacturing base.

If you're not in a hurry, you add about eight days per extra leg.

I tend to view things from a technological level fourteen base, and you could improve the performance twice of a factor three jump drive, like improving fuel efficiency.

It's also a case where the tendency would be for a back and forth ferry, so having a set of drop tanks at both termini makes sense.
 
I just looked at high guard again and they removed a very important line from the final version. Drop Tanks fail if you roll less than an 8. In the earlier versions of the book this risk was removed once the tank was TL 14 or above. That line has been removed. This could make for expensive travel if you roll average numbers.
 
I don't think any military would accept crucial and expensive hardware with a proven 56% average failure rate so that is just silly.

When something makes no sense in a later version of Traveller I always go back to the original source - which for drop tanks is the Little Black Book High Guard which makes no reference to their unreliability at all.
 
RogerMc said:
I don't think any military would accept crucial and expensive hardware with a proven 56% average failure rate so that is just silly.
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Current drop tanks have a failure rate of 100% when dropped, yet they are still found useful...
 
Current fuel tanks do not cost half the price of a ship hull per ton.

The Drop tank usage for shipping cargo only makes sense if the drop tank survives for multiple uses. Otherwise you are spending 10 million in drop tank to ship 2.8 million in cargo. (assuming 400 tons of fuel being replaced with 400 tons of cargo for a Jump 4). This makes no sense.
 
How is it failure when they have done their job.

Also it is 3rd Imperium canon that on 097-1105 General Shipyards announces it will begin producing drop tanks for commercial use at the TL-13 yard at Pixie.

Whatever High Guard may say Tukera or Oberlindes are never going to spend shareholder money on a technology that is 56% likely to fail at the only important function it has.

Now it is also canon that in 1106 one of those commercial ships may have been lost due to drop tank malfunction but that is hardly going to represent an average 56% failure rate.

Clearly there needs to be some chance of failure however but I'd put it at rolling a natural 2 on 2D level.
 
It depends on what you are saying their job is. If a 400 ton drop tank costing 10 million credits blows up after 2 uses, it is costing 5 million credits to save 800 tons of space on a ship. (400 tons per trip). That is pretty expensive on a per ton basis. Maybe it makes sense in certain aspects.

From a commercial operation, when the price per ton is 7000 credits on a j4 jump, it makes no economic sense. A reusable drop tank that allows an extra 2.8 million in cargo to be moved per trip makes excellent sense. The Drop tank pays for itself in a few trips and then keeps generating money.
 
As fail in this sense is a 56% chance of something costing 25,000 a ton not being recoverable at all it could make military but never commercial sense.

The only exception might be at the Jump-6 level where freight and passenger rates are so high that building a ship that has a J6 drive but all its fuel in drop tanks meaning that all the 60% usually filled by fuel is free for cargo (or even better cargo/fuel tanks) might make sense.
 
i.e. if you can get someone to pay you 86,000 a ton for shipping freight in your J6 ship then a 56% chance of writing off the 25,000 cost of the drop tank that makes it possible to do that jump with that cargo might just make sense.

The market for goods and passengers who are so time-sensitive that they will pay J6 rates must be pretty limited though....
 
PsiTraveller said:
The Drop tank usage for shipping cargo only makes sense if the drop tank survives for multiple uses. Otherwise you are spending 10 million in drop tank to ship 2.8 million in cargo. (assuming 400 tons of fuel being replaced with 400 tons of cargo for a Jump 4). This makes no sense.
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It not that simple...

A J-6 ship that can carry 1000 Dt payload is about 7000 Dt (incl. 4200 Dt fuel tanks) and costs MCr 2600.
A J-6 ship using drop tanks that can carry 1000 Dt payload is about 1500 Dt and costs MCr 600 plus a drop tank of 900 Dt and MCr 23.

It's expensive to jump around empty fuel tanks.
 
Also there are Imperial Nobles so rich that money is no object at all - so having a J-6 yacht that uses the 60% fuel space for a full-size ballroom or Olympic swimming pool (which is basically filled with unrefined fuel anyway...) because you use drop tanks might well make perfect sense and they may not even bother getting someone to recover the dropped tanks.
 
AnotherDilbert said:
It not that simple...

A J-6 ship that can carry 1000 Dt payload is about 7000 Dt (incl. 4200 Dt fuel tanks) and costs MCr 2600.
A J-6 ship using drop tanks that can carry 1000 Dt payload is about 1500 Dt and costs MCr 600 plus a drop tank of 900 Dt and MCr 23.

It's expensive to jump around empty fuel tanks.
Click to expand...

There you go and they can charge 84,000 credits per ton to fill that 1,000 payload or 84 MILLION credits a jump - so even writing off every drop tank the ship theoretically could pay for itself in just 10 trips...

However so limited would the demand for 84,000 credit per ton freight services be that I can't see you'd want as much as a 1000 dton payload.
 
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