jump stations, jump pods and jump 6 cargo hauling.

[jfwking]

Taking a couple of facts and adding an idea or three that came to me I have come up with the following:

Firstly the facts.

1 the 80/20 rule of jump fuel use, a ship only needs to take with it 20% of the jump fuel for use in the week of travel.
2. Drop tanks demonstrate that physical objects in contact with a ship can detach after offloading the 80% jump fuel used in the jump.
3. Xboats

Next a conclusion.
1. Astrogators can plot a jump without being on the ship they are plotting for so long as Imperial crew regs are met.

Firstly the jump station. A megaton range platform just over the jump limit. A few 100,000 tons of fuel, an extensive cargo handling and warehousing array. Hangers for a fleet of big fuel skimming boats, a very large power plant and one or more astrogators so good that they can easily plot jumps in safety allowing for the penalty of drop tank type interferance in the jump feild.

The jump pods are large (1000 - 100000) ton barges with a high jump drive, J4 to J6, a power plant to run this drive in jump and the 20% of "in flight" fuel.

The pod is conected to the jump station via power and fuel cables. Its jump capacitors are charged by the station which has a large enough power plant to do this in one go, the fuel to create the jump bubble is fed out and the jump is started. The cables are ejected out of the field and the ship jumps using a plot provided by the high skill astrogator on the station so no misjump chance.
At the destination the pods either move to another jump station or if xboat types are picked up by a pod tug. They off load/onload and then move out to a safe distance from the station to be cabled up for the next jump.

A 10000 dton pod with a J6 and 20% fuel is going to be able to carry 7000+ dtons of cargo 6 parsecs. A jump 4 unit to follow the xboat routes can carry 8000+ dtons.

Helps shift a bit of cargo round the Imperium a bit faster

 

[fredofmars]

A difficulty with your megaton station concept is that even if your station is a sphere (the most compact 3D object), your pod will need to be at least 30 (thirty) kilometers away from the station before it can jump safely. That is quite a long boom! Even in zero-g I don't think you'd want 30km of lhyd and live power lines snaking around without protection.
- Joseph

 

[Moose]

A further variation, albeit less integrated, would be to have automated drop tank-equipped jump barges manouevred to jump point by a specialised tug, within which you have the astrogation pilot and controls.

The flight crew on the tug initiate jump procedures and pick up the dropped tanks before returning to megaton station. It's a little less elegant, but entirely practical.

 

[rancke]

1 the 80/20 rule of jump fuel use, a ship only needs to take with it 20% of the jump fuel for use in the week of travel.
2. Drop tanks demonstrate that physical objects in contact with a ship can detach after offloading the 80% jump fuel used in the jump.
3. Xboats

Where is the 80/20 rule from? Back when I came up with the idea of jump projectors for a TCS game, many years ago, all the fuel was expended before a ship entered jumpspace.

(Steve Higginbotham, my GM, came up with a refinement: The station is a long cylinder that the ship flies through; the ship's jump grid gets charged by induction during the fly-through.)

A 10000 dton pod with a J6 and 20% fuel is going to be able to carry 7000+ dtons of cargo 6 parsecs. A jump 4 unit to follow the xboat routes can carry 8000+ dtons.

Helps shift a bit of cargo round the Imperium a bit faster

The capacitors needed for drop tanks to work wasn't invented until recently. You'd need a considerable investment in infrastructure to get this off the ground. With an existing merchant fleet capable of handling the current freight load, there may not be capital available. Or maybe such setups are being build in the Imperial core this very moment. Or maybe there are undisclosed reasons why it doesn't work. The Trimkhana Brilliance disaster may have exposed an unsuspected flaw in the process. If the jump projector turns out to have, say, a 1/1000th risk of exploding every time it is used, they're going the way of the Hindenburg PDQ.


Hans

 

[minipainter]

the automated tug Idea wouldnt work IMTU because jump drives are schrodinger type drives which acording to http://www.projectrho.com/rocket/rocket3a.html
require a person to be present to monitor them or they fail to work. Are you after a B5 type feel to your campaign? as the jump station dosent seem that different from a jump gate

 

[far-trader]

Where is the 80/20 rule from?

I think T20 was the first to set hard numbers to it and is the source of the 80/20 rule but I'm pretty sure I came up with the same ratio decades ago from the Gazelle and it's drop tanks.

 

[pendragonman]

the automated tug Idea wouldnt work IMTU because jump drives are schrodinger type drives which acording to http://www.projectrho.com/rocket/rocket3a.html
require a person to be present to monitor them or they fail to work. Are you after a B5 type feel to your campaign? as the jump station dosent seem that different from a jump gate

Because if there is no one there to monitor them there is no way to know if they are working or not? :rofl:

Fun link, btw.

 

[coliver988]

Because if there is no one there to monitor them there is no way to know if they are working or not? :rofl:

Fun link, btw.

Actually, if no one is there to observe, the drives are both working and not working. The ship is both in normal space and jump space. The basis of jump sickness - collapsing the probability wave into reality can be quite upsetting apparently.

 

[whartung]

Others have done this, but rather than using drop tanks, we used fuel containers and fuel shuttles to fill the ship just prior to jump.

Turns out to be very cost effective, even when you count the price of the infrastructure to support the jump limit outpost, and the ships etc to service it. especially for longer jump routes.

The best route was to have, effectively, "Cargo riders" -- jump ships that took external cargo pods. These ships, save for servicing, never made orbit, staying at the 100d limit.

The ships would pop in, be unloaded. Awaiting cargo would be loaded on to the ship, then the ship jumps out. Fuel is provided by local tankers that separate and maneuver away just before jump.

Fuel itself is refined at the gas giant, and tugs are used to push them to the outpost, where other tugs wait to catch them and push back empties. There's always a bunch of these in flight in the pipeline.

Similarly, tugs and the containers are move from the 100D output to highport for delivery. Basically, like freight yards and container yards.

There's a lot of margin to be made up, even with all that infrastructure, to recover that jump volume on those ships.

But this is a volume operation, none of your tramp 200t Free Trader stuff here.

 

[minipainter]

whartung is it still cost effective at lower jump ranges J1&J2? and do you have 1 jump ship per destination system or would a cargo have to make connections?

 

[whartung]

whartung is it still cost effective at lower jump ranges J1&J2? and do you have 1 jump ship per destination system or would a cargo have to make connections?

The assumption was that, using the drop tank concept, some minimum percentage of the jump fuel consumed for the jump was necessary to the ship AFTER drop tank were dropped (i.e. you could simply power the jump drive solely from the drop tanks, with zero remaining jump fuel on board the ship after the tanks are discarded).

I don't recall the numbers I used, but let's just be crass and assume it's the same as J1.

The overall goal was to use the tanker fleet to fuel and power the jump drive charge sequence rather instead of drop tanks, and replace the capacity normally used for jump fuel with cargo.

Using a contrived example of a Book 5 Jump 6 ship which would have to have, what, 60% of ship volume dedicated to Jump fuel? Something like that (TNE is much less, like 5% ship volume per jump). But if the "final phase of jump", the period after the drop tanks are discharged but before the ship jumps, only require fuel for J1, i.e. 10% for our Book 5 example, then that means that the ship would have gain 50% of its volume for cargo.

Since for a J1 ship, you gain nothing for having tanks (since, in this example, you need minimum J1 of fuel anyway), then obviously all of that infrastructure is for naught.

And with J2, the extra 10% cargo space gained probably is not enough to justify the expense of the infrastructure.

I think when I did it, I was doing the math for a J4 route, but I think it was still profitable for a J3 route.

Hunt down my posts, and you can find my write up from a year or two ago in a thread about Drop Tanks and see what my math came out in terms of margin. It effectively boiled down to any large freight company would certainly do this, and even if they couldn't do this specific technique, a large freight company would profit simply from having it's own fueling infrastructure to skim and deliver fuel rather than paying 100cr per ton for refined fuel. The margins worked out, just not as nicely as with the fuel pods.

 

[minipainter]

thanks I'll go huntin' posts then.

 

[Gadrin]

But this is a volume operation, none of your tramp 200t Free Trader stuff here.

Sounds likely that an interface line might hang around here for cargoes heading off the beaten path. These would be smaller ships, the type depending on the jump route to be taken. But likely they'd be subsidized for regular cargo hauls.

You could use a mass-driver to move cargo between orbit and the 100-D, depending on how security conscious the system is. Also to move fuel from the GG to the station. That would look like one automated high tech place with no-fly zones for the cargo and fuels to move thru.

How fast of acceleration can mass-drivers get ? Wonder just how reliable it'd be ?

Sounds like a Core-type world operation. I think the Beltstrike Module has a similar setup for LSP moving hunks of rock. I'll have to check it out.


>

 

[Scott Martin]

I was involved in a fairly lengthy discussion of this type of infrastructure in the last couple of years (on this board)

whatever the jump rating (although, as pointed out, higher jump ratings are unfeasable *without* using this type of concept) there is a significant cost savings in 2 areas:

1) You don't actually need a maneuver drive
2) The cost of a jump tank is far less than the cost of hull space
3) your drives etc. are sized for the ship doing the travel, not the cost of the ship AND FUEL TANK

For #2 and 3 consider a jump-5 ship. If it's 10 Ktons, you have 5 kTons to play with to move carge etc.

A 5 kton ship with drop tanks needs *2500* Dtons of drop tank, and that 5 Ktons that are left requires a 300 dT jump drive - compare this with the 600 dT drive for the 10 kTon ship carrying jump fuel. - your J-Drive costs just dropped by 50% for the same payload AND you have an additional 300 dT of cargo capacity.

If you're doing an 80/20 thing this margin shrinks, but is still a powerful incentive, even if you need to carry an astrogator and all the rest of the crew

Scott Martin