Vacuum rated cargo haulage

[Condottiere]

Chances are from zero onwards, based on technological level.

Also, same occurred with lanthanum grid, so jump bubble doesn't seem to factor in.

 

[phavoc]

Alternately the mass automatically causes the bubble to change shape to match the shape of the mass.

More likely considering the existence of Jump Nets the hull and jump net has something that causes the shape of the bubble to conform to that of the mass. Brings you back to hull grids. Docking clamps must also have this "something" though why there wouldn't be a cheaper docking clamp for non Jump ships is a mystery.

Yeah, possible. Though the issue with that line of thought would be that (for MGT at least) the jump fuel is rapidly converted to exotic particles that fill up the area around the ship in a sphere.

Though, now that I type this, I could see that if you ran pipes from the jump drive that's creating the particles to areas around the ship you could equally fill up the area around the ship to create your exotic particle bubble. The book does not say anything about this, but it would work and allow you to create that equally spaced bubble. It wouldn't work, possibly, with jump nets, though maybe if you were to channel more particles towards the area where your jump net was it could work out roughly the same way.

Using that idea is another non-canon breaking explanation that sidesteps the neener-neener-neener you're wrong crowd. And no hand wavium required either.

 

[phavoc]

Drop tanks don't get destroyed. I need to find it but somewhere there was a description of fleets jumping out with drop tanks and the service ships picking them back up for reuse. They would only really be lost if a mis jump resulted. And ships like the Gazelle that don't usually drop their tanks when they jump are fine.

They CAN be destroyed, though it's not a guarantee that they are. Master Gwydion posted the latest rules on them (which vary from original CT somewhat).

 

[mavikfelna]

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High Guard pages 48 and 49 seem to disagree with you.

I see no contradiction to what I said there. Drop tanks can survive being ejected. If ejected, they may interfere and cause a misjump and be destroyed.
They also don't have to be ejected, you can easily carry tanks large enough for multiple jumps and continue to use them or even keep them attached when empty. They will continue to affect jump and maneuver drive performance, even if empty, and if they are lower than TL15 built they increase misjump chance. Since there is no cost difference for the TL of the tanks, they will always be the highest local TL, and in the case of naval units should always be TL15.

 

[MasterGwydion]

I see no contradiction to what I said there. Drop tanks can survive being ejected. If ejected, they may interfere and cause a misjump and be destroyed.
They also don't have to be ejected, you can easily carry tanks large enough for multiple jumps and continue to use them or even keep them attached when empty. They will continue to affect jump and maneuver drive performance, even if empty, and if they are lower than TL15 built they increase misjump chance. Since there is no cost difference for the TL of the tanks, they will always be the highest local TL, and in the case of naval units should always be TL15.

No.

If you jump and use/jettison a drop tank, you roll an unmodified 2d6. On a roll of 8+ the tank survives. On a roll of 7- the tank is destroyed or damaged beyond repair.

You are talking about two separate things. One is the modifier to the Engineering roll for jump (based on the TL of the ship/drop tank), which can cause a misjump. The other is the unmodified 2d6 roll that you make that determines if your drop tanks survive or not but cannot cause a misjump.

See the difference?

 

[rinku]

If a ship has sufficient unused internal tankage you could also transfer the drop tank fuel to the ship, then detach (NOT jettison) the drop tanks safely, allowing reliable recovery. The ship would be able to move away to a safe distance and make a regular jump in that case. But forgoes the special advantage of a drop tank in regards to using fuel without it counting as jump tonnage.

 

[Condottiere]

If I recall correctly, both the external cargo mount, and drop tanks, have explosive bolts.

 

[phavoc]

There's no real reason to have explosive bolts to jettison external cargo. It would be far safer to either have spring-loaded or hydraulic rams to shove the external item away from the ship. Depending on how many you are ejecting (and the geometry of your ship and the placement of the external items) the ship itself could fire thrusters and maneuver in the opposite direction, which would increase your separation rate.

Per the MGT book, the creation of the exotic particle bubble at the time of jump does potentially increase the risk of external tanks not clearing the bubble prior to jump being initiated. I suppose an extremely forceful ejection could help (or say solid-rocket ejection motors on the tank to speed it away from the ship that is jumping). Keep in mind that physics still take place in space, so by pushing or shoving an external tank away from the ship that same ship will drift slightly in the opposite direction. This will throw off your jump calculations slightly, and over a parsec even a small deviation can mean a bigger error margin.

Just some things to keep in mind when thinking up how'd you like for this stuff to actually work. Or not if you don't care about the mechanics.

 

[MasterGwydion]

There's no real reason to have explosive bolts to jettison external cargo. It would be far safer to either have spring-loaded or hydraulic rams to shove the external item away from the ship. Depending on how many you are ejecting (and the geometry of your ship and the placement of the external items) the ship itself could fire thrusters and maneuver in the opposite direction, which would increase your separation rate.

Per the MGT book, the creation of the exotic particle bubble at the time of jump does potentially increase the risk of external tanks not clearing the bubble prior to jump being initiated. I suppose an extremely forceful ejection could help (or say solid-rocket ejection motors on the tank to speed it away from the ship that is jumping). Keep in mind that physics still take place in space, so by pushing or shoving an external tank away from the ship that same ship will drift slightly in the opposite direction. This will throw off your jump calculations slightly, and over a parsec even a small deviation can mean a bigger error margin.

Just some things to keep in mind when thinking up how'd you like for this stuff to actually work. Or not if you don't care about the mechanics.

Mount the drop tanks on either side of the ship, so when you explosively expel them, the net force on your ship is zero. Easy. No need to overthink it.

 

[Fluffy Bunny Feet]

Mount the drop tanks on either side of the ship, so when you explosively expel them, the net force on your ship is zero. Easy. No need to overthink it.

Or just include the motion change in the calculations.

 

[MasterGwydion]

Or just include the motion change in the calculations.

Why make the job harder instead of simply building the ship right to begin with? Why would you want to add another variable to the calculation? It doesn't cost any different having 2 drop tanks versus having one drop tank. Seems like having only one drop tank should get you a Bane on your calculations for using substandard equipment.

 

[Fluffy Bunny Feet]

The motion change should be pretty tiny and standard from trip to trip as the tank is just a hollow light weight shell and the ship has a heavier hull and lots of internal machinery, likely cargo as well increasing the mass differential. It also has a fraction of the ships volume. No bane as it is a standard thing designed for.

Finally of course the M-Drive could compensate for that tiny thrust leaving you not changing the ships motion.

 

[Condottiere]

With or without the jump bubble, the drop tanks have to pushed away far enough so that their gravitational field doesn't interfere with the transition.

If you think about it, if they crumbled like a aluminum can, their reduced volume would have an even less of an effect.

 

[MarcusIII]

If you think about it, if they crumbled like a aluminum can, their reduced volume would have an even less of an effect.

I don't know. Their volume isn't what determines their gravity field but their mass. If that is what causes an effect.

 

[MasterGwydion]

I don't know. Their volume isn't what determines their gravity field but their mass. If that is what causes an effect.

In reality, yes. In Traveller, no. Otherwise 100D jump limits wouldn't be a thing. They would instead be 0.01G jump limits from planetary gravity.

 

[Fluffy Bunny Feet]

With or without the jump bubble, the drop tanks have to pushed away far enough so that their gravitational field doesn't interfere with the transition.

Or planned use of the M-Drive to get beyond the 100 diameter distance in which case higher g drives should decrease the interference and increase the survival rates of the tanks.

 

[MasterGwydion]

Or planned use of the M-Drive to get beyond the 100 diameter distance in which case higher g drives should decrease the interference and increase the survival rates of the tanks.

Most ships do not have enough power to use the jump drive and the m-drive at the same time. Plus, all of the rules for jump tanks are under jump tanks. No amount of fluff about maybe I can use my m-drive. Nope. The jump tanks rule tells everyone exactly how it works mechanically. You can explain it anyway you want, but the truth of the matter is that even if you ship doesn't have an M-drive it has the exact same chances of having an issue with drop tanks as a ship with an M-drive. Why? Because the rules under drop tanks don't say anything other than what they say.

Plus, if you were really going to do this? Just put a repulsor bay on the ship and call it done. Still doesn't get around RAW, but as a Referee, I'd allow it.

 

[MarcusIII]

Otherwise 100D jump limits wouldn't be a thing.

The 100D limit is just an easy convenience. It IS supposed to be because of the gravity of the star rather than its volume. Marc didn't want to make it so complex that one had to know the mass of the star and calculate each time.

 

[MasterGwydion]

The 100D limit is just an easy convenience. It IS supposed to be because of the gravity of the star rather than its volume. Marc didn't want to make it so complex that one had to know the mass of the star and calculate each time.

Same reason ships use volume instead of mass. The whole game use volume instead of mass, except for personal-scale items. Because it is easier to know the size of things as opposed to the mass of things at a glance.

If you have a 50m diameter ship, you must get at least 5km away from it before you can jump or suffer the penalties. The mass doesn't matter.

 

[phavoc]

Mount the drop tanks on either side of the ship, so when you explosively expel them, the net force on your ship is zero. Easy. No need to overthink it.

One can mount them anywhere. However depending on your ships design and where they are placed, that may not be possible. While the game doesn't much care about structural issues, they are in fact a thing and you can cause structural damage if you don't have things braced properly for acceleration, let alone maneuvering.

IF one wants to make it semi-realistic, then your drop tanks have to be somewhat conformal, and also not occlude sensors, airlocks, turrets, etc. Assuming a ship takes on drop tanks on-planet then they also have to be placed so that they would not greatly interfere with air movement and need to be secured properly so they literally don't fall off on their own.

Some players don't care and it's just a line on the ship form and they are fine with that. Others might want to think about how one could reasonably place them so that factors into their play.

A ship can also simply induce a spin, jettison the tank and let physics fling it away from the ship in addition to the force used during the ejection process. That actually is a better in some ways as the ship itself is not having to counter it's own course as much. Probably pretty easily handled using automatic thrusters, but another thing to consider if you are plotting a jump and your calculations need to be precise.