Battle Riders

[baithammer]

And further countered by HG 2ed.

A ship’s Thrust must be recalculated when carrying
a drop tank, using the combined tonnage of the ship
and the drop tanks it carries.

Which implies the tank has mass that is added to the tonnage of the ship while still attached to the ship.

As for the jump.

1.)

To jump, a ship creates
a bubble of hyperspace by means of injecting highenergy
exotic particles into an artificial singularity.

Sounds like the energy dump.

2.)

The singularity is driven out of our universe, creating
a tiny parallel universe which is then blown up like a
balloon by injecting hydrogen into it.

Which sounds like after the energy is used to create the pocket universe the hydrogen is used to expand the bubble by being injected into the pocket.

[locarno24]

In 1e, it's only volume, not mass, that affects drive performance (sublight or jump). Which is why drop tanks matter- they're volume external to the hull - as do ships on docking clamps, whilst the rules don't give a monkeys whether internal cargo bays and hangars are empty or stuffed to the rafters with pallets of bonded superdense plates.

You can jump with tank attached (whether or not it's empty) and count as a ship of higher volume, or drain it and jettison it, jumping as your normal size but with the risk of the tank being in the vicinity of the coalescing jump bubble (hence the 'only need to recalculate if it's still attached when you jump')

So a 100dton ship with a 100dton tank can jump with the tank attached as a 200dton ship (which may limit how far the same j-drive can throw it, no matter how much fuel is available), or drain-and-jettison and jump (with a risk for nearby objects) as a 100dton ship......not that any feasible jump for a 100 dton ship needs 100dton of fuel, but you get the point.

The nearby tanks.....look at it this way: a planet has a 100d limit, within which there is a penalty to jumping. Theoretically, the tanks also have a 100d limit, and you're jumping inside that. Obviously they're nowhere near as massive, even to scale (because if you jettisoned them they are going to be a hollow object), so the penalty isn't as bad.

[baithammer]

Doesn't make much sense for the tank to not effect jump calculations where it effects m-drive performance, especially when the tank needs to remain attached until its used its payload.

If the tank were consumed by the jump process like caseless ammunition then it would make sense.

[phavoc]

So a 100dton ship with a 100dton tank can jump with the tank attached as a 200dton ship (which may limit how far the same j-drive can throw it, no matter how much fuel is available), or drain-and-jettison and jump (with a risk for nearby objects) as a 100dton ship......not that any feasible jump for a 100 dton ship needs 100dton of fuel, but you get the point.

So if you have a 100Dton ship and it drains 100Dtons of hydrogen from the ship....where does this 100Dtons of hydrogen go? Logically you cannot double your internal displacement. Under CT fuel was used to rapidly generate energy to power the jump capacitors, so you were converting mass into energy. That falls within the laws of physics.

But in MGT, the hydrogen is now used to create a jump bubble. Which means as you are draining the tank you have to create the bubble of exotic particles. Now if the bubble is formed and the ship then enters the bubble, this might be possible. But nothing I've seen indicates this. The idea is that the ship is at the center of the bubble and the bubble is expanded outwards. Which means the hydrogen has to be drawn and converted simultaneously.

The nearby tanks.....look at it this way: a planet has a 100d limit, within which there is a penalty to jumping. Theoretically, the tanks also have a 100d limit, and you're jumping inside that. Obviously they're nowhere near as massive, even to scale (because if you jettisoned them they are going to be a hollow object), so the penalty isn't as bad.

Agreed, if we are going by just mass, the 100D limit of a jump tank is pretty minor. A ship traveling at just 1G speed would rapidly leave the tanks behind (especially if the 1G speed had been maintained for even just an hour).

[AnotherDilbert]

So if you have a 100Dton ship and it drains 100Dtons of hydrogen from the ship....where does this 100Dtons of hydrogen go? Logically you cannot double your internal displacement. Under CT fuel was used to rapidly generate energy to power the jump capacitors, so you were converting mass into energy. That falls within the laws of physics.

But in MGT, the hydrogen is now used to create a jump bubble. ...

Some fuel is used to create the exotic particles needed to create hyperspace, some fuel is used to blow up the bubble. We have no idea about how much fuel is used for each purpose. If relatively small amounts of fuel is used to blow up the bubble there is no problem.

Agreed, if we are going by just mass, the 100D limit of a jump tank is pretty minor. A ship traveling at just 1G speed would rapidly leave the tanks behind (especially if the 1G speed had been maintained for even just an hour).

The dropped tank would of course have the same velocity vector as the ship when it is dropped. With no air resistance it will keep that speed. It will not be left behind.

[AnotherDilbert]

Doesn't make much sense for the tank to not effect jump calculations where it effects m-drive performance, especially when the tank needs to remain attached until its used its payload.

The tank affects performance when it is attached.

Normal scenario:
1. You attach the tank at the starport.
2. You accelerate towards the 100D limit. The tank is attached so it affects performance.
3. You drop the tank.
4. You immediately jump. The tank is not attached, so performance is not affected.
5. You arrive at the destination and accelerate towards the starport. You have no tank attached, so performance is not affected.

The same rules apply to craft attached with docking clamps and external cargo.

[baithammer]

Some fuel is used to create the exotic particles needed to create hyperspace

Not according to the notes I mentioned, it only mentions hydrogen directly used to expand the pocket. What is mentioned is exotic particles which hydrogen isn't and could be generated due to the massive energy dump into the jump drive.

Normal scenario:
1. You attach the tank at the starport.
2. You accelerate towards the 100D limit. The tank is attached so it affects performance.
3. You drop the tank.
4. You immediately jump. The tank is not attached, so performance is not affected.
5. You arrive at the destination and accelerate towards the starport. You have no tank attached, so performance is not affected.

Which is contrary to the order presented in the drop tank section.

1.)

To jump, a ship creates
a bubble of hyperspace by means of injecting highenergy
exotic particles into an artificial singularity.

Sounds like the energy is used to generate the singularity sort of like a particle collider.

2.)

The singularity is driven out of our universe, creating
a tiny parallel universe which is then blown up like a
balloon by injecting hydrogen into it.

Which appears to suggest the hydrogen is pumped at the end of the jump sequence in order to cover the ship.

Also gets around the problem of tanks being a free pocket of fuel without any independent volume. ( Could be simulated by splitting the mass required for the coupling to add volume for the tank independently.)

Going to make changes to my ship building template to make distinction for external stores.

[phavoc]

Some fuel is used to create the exotic particles needed to create hyperspace, some fuel is used to blow up the bubble. We have no idea about how much fuel is used for each purpose. If relatively small amounts of fuel is used to blow up the bubble there is no problem.



The dropped tank would of course have the same velocity vector as the ship when it is dropped. With no air resistance it will keep that speed. It will not be left behind.

No, we don't have any idea. There is a lot of hand wavium going on here. Assuming the pocket universe is created instantly, you still are limited by physics in just how fast small tunes can pump liquid hydrogen into that universe and convert it to gaseous form. It obviously can't be liquid due to displacement issues. I've always considered the MGT switch to be a step in the wrong direction. At least the zuchai crystal and lanthanum grid and jump capacitors made for a more believable argument. The curent one went off in the wrong direction for no good reason, or at least no good reason I've yet to discover.

And yes while the tank will take on the velocity of the ship that drops it will still be left behind as the ship continues to thrust. The idea of continued thrust works in the ships favor since a vector change can increase the delta between their relative positions.

[AnotherDilbert]

No, we don't have any idea. There is a lot of hand wavium going on here. Assuming the pocket universe is created instantly, you still are limited by physics in just how fast small tunes can pump liquid hydrogen into that universe and convert it to gaseous form. It obviously can't be liquid due to displacement issues. I've always considered the MGT switch to be a step in the wrong direction. At least the zuchai crystal and lanthanum grid and jump capacitors made for a more believable argument. The curent one went off in the wrong direction for no good reason, or at least no good reason I've yet to discover.

The jump bubble comes from T5?

And yes while the tank will take on the velocity of the ship that drops it will still be left behind as the ship continues to thrust. The idea of continued thrust works in the ships favor since a vector change can increase the delta between their relative positions.

In a second that is only a few metres. I guess we will not have more than a few seconds from separation to jump?

[baithammer]

Given the description of drop tanks and the rules governing the ejection, the tanks are launched with significant force / velocity to sometimes out distance the expanding jump bubble.

[phavoc]

The jump bubble comes from T5?

No, jump bubble idea originated in MGT v1.

In a second that is only a few metres. I guess we will not have more than a few seconds from separation to jump?

A second might be too little time. The jump bubble concept complicates the original idea because before it was a question of a charge being held by the jumping ship. Now it's a bubble formation, which since you must physically pump liquid hydrogen into your new bubble (which is assumed to be a newly-created vacuum) that liquid turns to gas because of no pressure. Your pipes aren't going to be huge because that means they displace space that is already at a premium inside a ship. Plus, based on the mechanics of the ship, the drop tank needs to be routed through the jump drive machinery just like the internal fuel tank does.

The MGT usage of drop tanks is a bigger stretch to the idea from CT because of the change in the jump mechanism.

[phavoc]

Given the description of drop tanks and the rules governing the ejection, the tanks are launched with significant force / velocity to sometimes out distance the expanding jump bubble.

That's more of an assumption than a rule I think. But that's not uncommon with the MGT rules. They are written pretty loosely and are very interpretable.

[AnotherDilbert]

The jump bubble comes from T5?

No, jump bubble idea originated in MGT v1.

Thanks, I seem to have skimmed the MgT1 core book a bit too briefly.

I checked the old JTAS article, the descriptions of entering jump seems to be not mutually exclusive, merely light on details. They might possibly describe the same phenomena...

Only T5 defines the size of the bubble to be much larger than the ship?

[AnotherDilbert]

Some fuel is used to create the exotic particles needed to create hyperspace

Not according to the notes I mentioned, it only mentions hydrogen directly used to expand the pocket. What is mentioned is exotic particles which hydrogen isn't and could be generated due to the massive energy dump into the jump drive.

And where does the energy and exotic particles needed to create the bubble of hyperspace come from if not the jump drive and its fuel?

When the jump drive is activated, a large store of fuel is fed through the ship power plant to create the energy necessary for the jump drive. In the interests of rapid energy generation, the power plant does not work at full efficiency, and some of the fuel is lost in carrying off fusion by-products, and in cooling the system.

So, even as we generate the necessary energy, we are venting some excess hydrogen.

Normal scenario:
1. You attach the tank at the starport.
2. You accelerate towards the 100D limit. The tank is attached so it affects performance.
3. You drop the tank.
4. You immediately jump. The tank is not attached, so performance is not affected.
5. You arrive at the destination and accelerate towards the starport. You have no tank attached, so performance is not affected.

Which is contrary to the order presented in the drop tank section.

Not that I can find?

..., these are external fuel tanks that are jettisoned just as the ship enters jump space.

You carry the tanks, until just before the jump, when they are jettisoned.

Given the description of drop tanks and the rules governing the ejection, the tanks are launched with significant force / velocity to sometimes out distance the expanding jump bubble.

So you do agree the tanks are jettisoned before the jump?

[baithammer]

And where does the energy and exotic particles needed to create the bubble of hyperspace come from if not the jump drive and its fuel?

Considering the jump drive is creating a singularity that requires a great deal of energy, most likely pulls in the exotics through interaction with singularity.

So, even as we generate the necessary energy, we are venting some excess hydrogen.

Jump fuel isn't excess, it directly expands the bubble and you need the right amount of it to complete a jump.

3. You drop the tank.
4. You immediately jump. The tank is not attached, so performance is not affected.

The energy dump to jump drive occurs before pumping hydrogen in order to expand the bubble, so the tank needs to be attached until then unless there is some magical place to store all that hydrogen.

So the order is.

1. You attach the tank at the starport.
2. You accelerate towards the 100D limit. The tank is attached so it affects performance.
3. Initiate jump sequence by pumping the required amount of power.
4. Expand the jump bubble with the tanks hydrogen.
5. Once the pumping is complete the tank is ejected and the jump takes place.
6. Make the check to see if tank survives.
7. Take a break for 149 - 154 Hours.
8. Arrive at destination with no attached tank and make your way to the destination.

[phavoc]

Under this idea no ship would need jump fuel tanks, they could simply always use drop tanks. That is not how the Traveller universe works.

I think at TL14 drop tanks always survive a jump. Though I don't know how you can create a bubble and them shove your tanks out of it. That would seem to me that you risk a deflation or collapse of the bubble. There is no mention of any kind of field emitter to hold the bubble, so I'm assuming there is nothing of the sort. Thus puncturing the bubble with something as large as drop tanks would be catastrophic to the jumping ship.

Drop tanks really alter the mechanics of ship design and jump travel. It's one thing to add tankage externally and carry it through jump. It's another to cheat the system and skip the requirement of carrying your fuel internally, or at at least having to factor it into your operations and ship design.

[Sigtrygg]

Here is the actual CT canon; you will find that in 1105 civilian shipping in the core sectors have been using drop tanks for a couple of decades in order to carry more passengers and or cargo per trip.

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.

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.

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 fromsthe 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 jump5.5
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.

[AnotherDilbert]

Under this idea no ship would need jump fuel tanks, they could simply always use drop tanks. That is not how the Traveller universe works.

As Sigtrygg points out Drop Tanks have been available since CT.

Drop Tanks are not free, they cost money and are only available at the right starports. There are good reasons not to use them.

[AnotherDilbert]

So the order is.

1. You attach the tank at the starport.
2. You accelerate towards the 100D limit. The tank is attached so it affects performance.
3. Initiate jump sequence by pumping the required amount of power.
4. Expand the jump bubble with the tanks hydrogen.
5. Once the pumping is complete the tank is ejected and the jump takes place.
6. Make the check to see if tank survives.
7. Take a break for 149 - 154 Hours.
8. Arrive at destination with no attached tank and make your way to the destination.

So we basically agree?

Normal scenario:
1. You attach the tank at the starport.
2. You accelerate towards the 100D limit. The tank is attached so it affects performance.
3. You drop the tank.
4. You immediately jump. The tank is not attached, so performance is not affected.
5. You arrive at the destination and accelerate towards the starport. You have no tank attached, so performance is not affected.

[baithammer]

Under this idea no ship would need jump fuel tanks, they could simply always use drop tanks. That is not how the Traveller universe works.

If you read my steps the tank is attached through out the process so counts towards the jump mass calculation, especially with the tank needing to be empty and ejected at the end of the sequence.

I think at TL14 drop tanks always survive a jump. Though I don't know how you can create a bubble and them shove your tanks out of it. That would seem to me that you risk a deflation or collapse of the bubble. There is no mention of any kind of field emitter to hold the bubble, so I'm assuming there is nothing of the sort. Thus puncturing the bubble with something as large as drop tanks would be catastrophic to the jumping ship.

Confining this to MGT High Guard 2ed, which has specific rules on if the tank survives.

It's another to cheat the system and skip the requirement of carrying your fuel internally, or at at least having to factor it into your operations and ship design.

Which is addressed by the new jump sequence mentioned under drop tanks.

Drop Tanks are not free, they cost money and are only available at the right starports. There are good reasons not to use them.

Referring to free mass / displacement not cost, which is fixed for the reason mentioned above.

So we basically agree?

If you moved step #3 to after step #4 and delete the second part of the sentence of step #4.

There is no way that the tank should be able to be dumped before the jump takes place and undermines physics. ( The hydrogen has to have somewhere to go between the tank and the jump drive.)

Also breaks the physics where internal storage would be a subpar choice with drop tanks having no drawbacks in standard operation.