Jump Bubble diameter and location of Jump Drive
- Thread starter Condottiere
- Start date
The rules say nothing about the physical configuration of the drives. However, you can infer (if you like) some things from the formulas implied by the drive size and cost tables.
First, each drive has a 5dt "control room" overhead, which is essentially free, or bundled with the cost of the hull+drive in some way.
Second, each letter corresponds to a number of 5dt jump "units", which costs 10MCr each. Larger hulls require more jump units, but not larger control rooms.
There is no economy of scale in drive cost or size. More capable drives seem to just take more of the 5dt "units" to achieve their effect.
Now of course such a view requires you interpret the data, since as F33D will be happy to point out
, the RAW are silent on the subject, which means the GM is free to improvise.
In my current campaign (which is on hold for a while, but still technically "on") I'm using the trope (from Twilight's Peak) of the Far Trader with "short legs". In this case, the players need to buy a new jump module or repair the old one in some way. Their control room can handle two modules (class B), but one is malfunctioning.
First, each drive has a 5dt "control room" overhead, which is essentially free, or bundled with the cost of the hull+drive in some way.
Second, each letter corresponds to a number of 5dt jump "units", which costs 10MCr each. Larger hulls require more jump units, but not larger control rooms.
There is no economy of scale in drive cost or size. More capable drives seem to just take more of the 5dt "units" to achieve their effect.
Now of course such a view requires you interpret the data, since as F33D will be happy to point out
, the RAW are silent on the subject, which means the GM is free to improvise.In my current campaign (which is on hold for a while, but still technically "on") I'm using the trope (from Twilight's Peak) of the Far Trader with "short legs". In this case, the players need to buy a new jump module or repair the old one in some way. Their control room can handle two modules (class B), but one is malfunctioning.
Egil Skallagrimsson
Mongoose
Reynard said:
Dunno, you will have to ask Alice that one.
Rikki Tikki Traveller
Cosmic Mongoose
Personally, for MyTU, I like the idea of a spherical Jump Bubble. The jump drive is then located in the center of the ship and ALL FTL capable ships are spheres.
SO, that really changes the composition of a naval fleet with Battle Riders much more likely. It also makes Hi Ports much more common (say Starport Class-C or better always have them) and most smaller ports use shuttle service.
Of course almost none of the "standard" layouts would apply, but since I like designing ships, I wouldn't mind. The Tigress would work though!
You could probably come up with some kind of ship size penalty for a Flattened Sphere design (wasted volume of the jump bubble) and that MIGHT allow a smaller craft to fit within that jump bubble and not be directly connected to the other ship. Referee's decision.
It would likely make the game more like the Humanx Commonwealth of the Flinx stories.
SO, that really changes the composition of a naval fleet with Battle Riders much more likely. It also makes Hi Ports much more common (say Starport Class-C or better always have them) and most smaller ports use shuttle service.
Of course almost none of the "standard" layouts would apply, but since I like designing ships, I wouldn't mind. The Tigress would work though!
You could probably come up with some kind of ship size penalty for a Flattened Sphere design (wasted volume of the jump bubble) and that MIGHT allow a smaller craft to fit within that jump bubble and not be directly connected to the other ship. Referee's decision.
It would likely make the game more like the Humanx Commonwealth of the Flinx stories.
Condottiere
Emperor Mongoose
I like to thank everyone for replying to my questions.
I was considering spherical starships ala early Perry Rhodan,and wondered if you could shrink the jump bubble to hug the hull. If an exterior bulkhead were required, I considered making it a berliner, with the drives still central, but an exhaust port giving it a somewhat semi doughnut structure.
I was considering spherical starships ala early Perry Rhodan,and wondered if you could shrink the jump bubble to hug the hull. If an exterior bulkhead were required, I considered making it a berliner, with the drives still central, but an exhaust port giving it a somewhat semi doughnut structure.
Condottiere said:
Hi Condottiere. The following are the guidelines I use when writing Traveller material.
1. What's the diameter of the Jump Bubble?
Diameter = (Hull Tons * 13.5 )^1/3 *20 (in meters)
and
For most purposes, a Jump Bubble is about five times the diameter of the average of Length, Width, and Height of the ship and centered on the Jump Drive.
I think of it as: the radius from the jump drive to the end of the ship from which the drive is furthest from. That probably works out to the same thing, since most ships are much longer in one dimension than the other two, but the concept is that the bubble encompasses the ship, and is centered on the jump drive.
2. Does the diameter vary, depending on the tonnage of the drive, it's damage status, etcetera?
The diameter varies based on construction of the jump drive and the needs of the ship. If the jump drive is on the extreme end of the ship, the jump bubble will probably be quite large.
The bubble is the default, and cheapest, option. Two other options, Jump Plates, and a Jump Grid, offer tighter hull conformance -- and their own advantages and disadvantages.
3. Does the Jump Drive have to be placed on an exterior bulkhead or can you have them in the starship core?
It may be placed anywhere, but this will affect the bubble size.
4. Can Jump Drives be yoked in series, as long as the final tonnage equals to the required size necessary for the planned jump?
Yes, on the condition that the drives must be identical.
For example, an N2 or NN jump drive consists of two N jump drives. A Z9 drive is nine Z drives.
5. Do smallcraft need to be grappled during the jump, or if unsecured, could they drift and will they penetrate the Bubble boundaries?
They need to be in contact with the ship during jump, or else they are lost in jumpspace. Whether or not they 'drift' before being lost is unknown to me.
Condottiere
Emperor Mongoose
Seems more rule of thumb since how would the Jump Drive know the dimensions of the ship, as compared to having an installed grid that would tell it exactly?
Among other things that vex me are the Alphabet drives, which I assume are supposed to be commercial off-the-shelf variants, since presumably I could install a higher value one on the starship, and have it jump six parsecs, even if the ship was constructed at a much lower TL. Since jump technology is an equivalent to dweomercraft, I suppose you could restrict it based on the limitations of the software programmes needed for astrogation, whereas you couldn't make that excuse for maneuver drives, where brute force could make them go any speed and passenger safety would be the only constraint, ie inertial compensation available or acceleration couches/tanks.
Among other things that vex me are the Alphabet drives, which I assume are supposed to be commercial off-the-shelf variants, since presumably I could install a higher value one on the starship, and have it jump six parsecs, even if the ship was constructed at a much lower TL. Since jump technology is an equivalent to dweomercraft, I suppose you could restrict it based on the limitations of the software programmes needed for astrogation, whereas you couldn't make that excuse for maneuver drives, where brute force could make them go any speed and passenger safety would be the only constraint, ie inertial compensation available or acceleration couches/tanks.
GypsyComet
Emperor Mongoose
Condottiere said:
The software and the computer to run it are stated limitations and do have TL thresholds in MGT, so yes.
1 metre distance from I know i have seen it in T20, believe I have seen it somewhere else to.
In T20 and from what I have seen for CT i think, and Mongoose the jump drive has one external part in all of them, which takes no real mass. This is the jump grid, which I have seen used as small nodes placed around the hull. These make sure that the bubble does encroach on the ship destroying it, or part of it. So, in response to a ship that has a breach, the simple answer is not really unless you want a major misjump or complete destruction. However, one can simply re grid the jump grid around the ship so that it takes in account of missing grid nodes and prevents it from misjumps.
You can potentially exit the ship and stay with in the 1 metre zone, but you'd be having to look at the hull at all times. This would be true for what I have seen that mongoose has put of a hydrogen bubble. Because the person would still have to be in a Vacc suit. Though that would be something worthy of debate on if that is safe.
But in general, I wouldn't advise it. Too many risks involved. Cramped space, constant evasion of looking at something that will make you either sick or insane or worse. As well as normal EVA troubles. Would be very high pressured on whoever did try it so to speak.
In T20 and from what I have seen for CT i think, and Mongoose the jump drive has one external part in all of them, which takes no real mass. This is the jump grid, which I have seen used as small nodes placed around the hull. These make sure that the bubble does encroach on the ship destroying it, or part of it. So, in response to a ship that has a breach, the simple answer is not really unless you want a major misjump or complete destruction. However, one can simply re grid the jump grid around the ship so that it takes in account of missing grid nodes and prevents it from misjumps.
You can potentially exit the ship and stay with in the 1 metre zone, but you'd be having to look at the hull at all times. This would be true for what I have seen that mongoose has put of a hydrogen bubble. Because the person would still have to be in a Vacc suit. Though that would be something worthy of debate on if that is safe.
But in general, I wouldn't advise it. Too many risks involved. Cramped space, constant evasion of looking at something that will make you either sick or insane or worse. As well as normal EVA troubles. Would be very high pressured on whoever did try it so to speak.
Keep in mind the old 1 meter distance from the hull to the jump field was put forth when ships had a lanthanum grid in their hull to generate the drive field. MGT changed that with the jump bubble filled with hydrogen.
I'm not sure how opening the airlocks would equate to suicide though.
I'm not sure how opening the airlocks would equate to suicide though.
GypsyComet
Emperor Mongoose
The physics beyond the bubble is lethal to human life, but it may take the combination of the bubble and the hull to completely protect life.
Idea: the physics of jump space are somewhat Boyle's Law like. The more you compress J-Space away from the hull, the more energy it has and the more weirdness it radiates through the bubble. The large bubble is just as unsafe to life as the smaller fields a meter off the hull.
Idea: the physics of jump space are somewhat Boyle's Law like. The more you compress J-Space away from the hull, the more energy it has and the more weirdness it radiates through the bubble. The large bubble is just as unsafe to life as the smaller fields a meter off the hull.
