Collapsibles and Drop Tanks

[Mike Wightman]

Unfortunately for those who just wish to ignore them the use of drop tanks is one of the earliest bits of setting fluff we ever got for the 3I setting.

REGINA/REGINA (031 0-A788899-A) Date: 097-1 105
Officials of the General Shipyards on Regina today announced that they have completed negotiations with Tukera Lines to locally manufacture L-Hyd drop tanks for use on high-capacity commercial vessels. The first production examples are expected to be available within six months, at which time Tukera Lines will begin high capacity service from the interior. Component assembly will be carried out at General's more modern facilities on Pixie (0303-A100103-D).

L-Hyd drop ships have only been in service for the last dozen years in the interior, being made possible by recent advances in the field of capacitor engineering, a joint press release explained. Commercial vessels equipped with the new generation of long-storage jump capacitors carry jump fuel in specially designed L-Hyd drop tanks in excess of their rated tonnage. Upon conversion of the fuel to the massive energy required for jump, the drop tanks are explosively jettisoned through the use of break-away connections and explosive bolts. Jump is executed when the remains of the tanks are a safe distance from the vessel. A spokesman for General Shipyards explained that local yards are not yet capable of manufacturing the long-storage capacitors required for the process, but that production of the drop tanks is possible, thus allowing the high capacity starships of the Tukera Lines to begin service to the Regina subsector.

L-Hyd drop tanks are not reusable, and thus increase the absolute cost per jump. However, experience has shown that the increase in cargo tonnage resulting from the elimination of internal J-fuel storage more than makes up for this, the press release explained.
The joint press release concluded by stating that local manufacture of L-Hyd drop tanks marked the dawn of a news era of commerce and prosperity in the Regina subsector. Following the announcement, common stock in Oberlindes Lines plummeted 27 points on the Regina exchange before trading was suspended.
Officials of Oberlindes Lines were not available for comment.

REGINA/REGINA (0310-A788899-A).Date: 101-1105
Close on the heels of the joint announcement by General Shipyards and Tukera Lines that L-Hyd drop tanks would soon be manufactured in the Regina subsector, came word by express boat from the Imperial core that a decision has been made to deploy Jump-6 L-Hyd drop tank express boats on all major express routes. Initial feasibility studies indicate that such a system could average jump 5.5 per week by executing maximum jumps where possible, and leaving current xboat units to disseminate information between the new major relay points. The system is expected to cut communication time to the lmperial hub to under 25 weeks.
The Initial System Deployment Schedule indicates that the Regina subsector can expect to be fully integrated into the network within a decade.

Well either those 'senior grognards' on the GT starships discussion got it completely wrong or possibly drop tanks are being confused with demountable tanks and other forms of additional fuel stowage which do require fuel to moved to regular tanks before it can be used.

Canonically drop tanks can be used to provide all the fuel needed for a jump and then they are dropped, not carried through jump. In the destination system a new set of tanks will be needed for subsequent jumps. Hence the setting description of them being used on the high capacity trade routes of the interior sectors.

[jason taylor]

Originally Posted by Mike Wightman

Unfortunately for those who just wish to ignore them the use of drop tanks is one of the earliest bits of setting fluff we ever got for the 3I setting.



Well either those 'senior grognards' on the GT starships discussion got it completely wrong or possibly drop tanks are being confused with demountable tanks and other forms of additional fuel stowage which do require fuel to moved to regular tanks before it can be used.

Canonically drop tanks can be used to provide all the fuel needed for a jump and then they are dropped, not carried through jump. In the destination system a new set of tanks will be needed for subsequent jumps. Hence the setting description of them being used on the high capacity trade routes of the interior sectors.

If they are not carried through jump, what is the point? Surely a standard tank would do.

[Mike Wightman]

I build a 1000t jump 6 ship. 60% is fuel.

I use drop tanks for the fuel, I can now transport 600t of cargo instead of empty fuel tank.

Downside is I need drop tank manufacture at both systems.

[tanksoldier]

Originally Posted by jason taylor

If they are not carried through jump, what is the point? Surely a standard tank would do.

The advantage age is the jumping ship is smaller when it jumps and the jump fuel doesn’t take up internal volume.

The Gazelle being discussed effectively has 100dt of fuel its 300dt hull doesn’t have to contain... and when it jumps it does do as a 300dt ship, not a 400dt ship.

Originally Posted by Mike Wightman

Downside is I need drop tank manufacture at both systems.

For commercial ships maybe, military ships have more options.

a Gilligan's Island position.

In canon the fuel is used and the tanks are dropped before the jump.

A Gazelle can make J2 on internal fuel and J5 with drop tanks if they are dropped pre jump.

...not a J2 then a J3.

[Fred Brackin]

Originally Posted by tanksoldier

T
For commercial ships maybe, military ships have more options.



In canon the fuel is used and the tanks are dropped before the jump.

A Gazelle can make J2 on internal fuel and J5 with drop tanks if they are dropped pre jump.

...not a J2 then a J3.

A J2 in and a J2 or 3 out is an option.

Also, even for the military tank retention is probably more common due to budgetary reasons.

[tanksoldier]

Originally Posted by Fred Brackin

A J2 in and a J2 or 3 out is an option.

Also, even for the military tank retention is probably more common due to budgetary reasons.

An option I mentioned several post ago.

...everybody realizes recovering the dropped tanks is the norm, right?

[malloyd]

Originally Posted by Mike Wightman

Canonically drop tanks can be used to provide all the fuel needed for a jump and then they are dropped, not carried through jump. In the destination system a new set of tanks will be needed for subsequent jumps. Hence the setting description of them being used on the high capacity trade routes of the interior sectors.

I think the core problem here is early Traveller authors didn't have a good feel for energy content of fuel. Ship designs are probably based on the kinds of tankage you might see in an oil powered naval warship, and a lot of stuff seems to assume that hydrogen fusion produces power levels not too dissimilar to combustion - hence the fuel requirements of power plants, the ability of unique ships to make jumps with solar power, and here the ability to burn all this stuff and store the energy in "capacitors" somehow without this technology obsoleting all other power plants, or letting you crack planets. This stuff probably *can't* be made to make sense, if you are going to preserve it's canon status you just have to take it at face value, and not try to work through the implications or logical alternative approaches.

[cptbutton]

Originally Posted by malloyd

I think the core problem here is early Traveller authors didn't have a good feel for energy content of fuel. Ship designs are probably based on the kinds of tankage you might see in an oil powered naval warship, and a lot of stuff seems to assume that hydrogen fusion produces power levels not too dissimilar to combustion - hence the fuel requirements of power plants, the ability of unique ships to make jumps with solar power, and here the ability to burn all this stuff and store the energy in "capacitors" somehow without this technology obsoleting all other power plants, or letting you crack planets. This stuff probably *can't* be made to make sense, if you are going to preserve it's canon status you just have to take it at face value, and not try to work through the implications or logical alternative approaches.

That is my assumption. They knew fusion was more energy-intense per kilogram than combustion, but thought it was 100 or 1000 times better, when it is actually more like 1,000,000 times better.

As I recently posted, IMTU most jump fuels is really protection from hyperspace, there are no jump capacitors, and drop tanks are much more expensive, require a ship with an overly large jump drive, and have to be retained throughout jump. But that clearly breaks with canon.

[Anaraxes]

Originally Posted by cptbutton

As I recently posted, IMTU... drop tanks are much more expensive, require a ship with an overly large jump drive, and have to be retained throughout jump.

So what makes them "drop" tanks, as opposed to a ship design that for whatever reason chooses to put the fuel tanks on the exterior of another "main" hull? What's droppable?

The "overly large jump drive" suggests that you have to equip the ship as if the tankage were part of the hull. So why not just build the ship that way with the regular design sequence, and say there are no such things as "drop tanks"? There has to be some practical difference for the naval architects to have a different bit of jargon.

Do you ignore the volume of drop tanks for purposes of ship displacement for performance? "Overly large drives" suggests not, but perhaps you have lesser fuel use, even though the drive is sized for the full displacement including the drop tanks?

[cptbutton]

Originally Posted by Anaraxes

So what makes them "drop" tanks, as opposed to a ship design that for whatever reason chooses to put the fuel tanks on the exterior of another "main" hull? What's droppable?

The "overly large jump drive" suggests that you have to equip the ship as if the tankage were part of the hull. So why not just build the ship that way with the regular design sequence, and say there are no such things as "drop tanks"? There has to be some practical difference for the naval architects to have a different bit of jargon.

Do you ignore the volume of drop tanks for purposes of ship displacement for performance? "Overly large drives" suggests not, but perhaps you have lesser fuel use, even though the drive is sized for the full displacement including the drop tanks?

I build a 300 dton ship with 180 dtons of internal tanks. I put in a jump 3 drive sized for a 400 dton ship. I add 100 dtons of external tanks, with jump grids built into them, with appropriate connections to the jump drive and main ship jump grid.

With full tanks attached, as a 400dton ship, I jump 3 parsecs, using 120 dtons of fuel. I detach the empty tanks, leaving me with a 300 dton ship with 160 dtons of fuel. I can now jump 3 more parsecs (90 dtons of fuel), and then 2 more parsecs (60 dtons of fuel). I end up dry 8 parsecs from home.

If I built a straight 400 dton J3 ship with 280 dtons of internal tanks, I could only do two 3 parsec jumps (120 dtons each) and a 1 parsec jump (40 dtons), ending up dry 7 parsecs from home.

So this ship can go 1 parsec farther without refueling. This might be useful in special situations. (But it has left the tanks behind, which is either a loss or must be recovered somehow.)

(I assume jump drives can be run at lower settings with lower fuel use, which may not be clear canonically.)

(I haven't actually run the numbers for such a ship design, sorry.)