Fleet Jumps

[phavoc]

With the questions about the re-publishing of the Sector Fleet (i.e. Grand Fleet) being bandied about in the other thread, I went back to the Core rulebook and re-read the specifics on jumps.

Basically jumping into a star system, especially an enemy one, as a fleet is a statistical improbability. Every ship has the standard period that it will exist in it's 'pocket universe', but there is also a random timeframe from 6 to 36hrs that it will stay in jump space. This means that "fleet" jumps, or having large numbers of ships appear is unlikely at best. With the random factor added in, you are going to (most likely) see an invasion fleet start randomly popping into your system. And nobody knows the order that they are gonna appear in.

I had also speculated about the potential of interpenetration of ships jumping into a system and appearing inside of another ship. Well, a re-read of the rules would preclude that (at least that is how I interpret them). Since (technically) ANY object with sufficient mass will yank a ship out of jumpspace if it breaches the 100diameter rule, a ship should (again, in theory) never be able to enter normal space within 100 diameters of the opposing ship. So if you had a 40m long intrasystem freighter poking along and a 25,000 ton cruiser happened to drop out of jump space, it would be a minimum of 400 meters away from the freighter.

Yeah, yeah, I know, I'm not using diameter measurements properly, but since I don't have those, I just used the length as an example.

Comments? Now DFW... don't be shy!

 

[steelbrok]

This is one thing that favours Battle Riders rather than Battleships for an offensive. You can guarantee that the squadron will all arrive at once

 

[E.D.Quibell]

The notion of a squadron jump is one that has been around for a while.

Basically each ship in the squadron is tied into the same jump with the same jump co-cordinates, and all ships excicute the jump at the same time with the same sequence.

The jump is still variable, but it's variable for the squadron, and all the ships arrive at the destination at the same time.

It takes longer to set-up the jump in the first instance.

I can't find any references at present, but I'm sure somone else will jump in with them.

Best regards,

Ewan

 

[phavoc]

References would be nice. I have yet to find any references in the MGT rules that cover jumps. Astogation checks will get you to where you want to go, but as far as I can tell, the rules state that jump travel varies at the SHIP level... ergo no matter how accurate your jump estimates are, each ship will pop out of their pocket universe with a random time factor of 6d6 (6 - 36hrs).

An explanation of jump travel is not even listed in high guard that I recall.

 

[IanBruntlett]

Basically jumping into a star system, especially an enemy one, as a fleet is a statistical improbability.

In MTU we don't do much with spaceships, They get us from A to B etc. However, I would definitely have some excuse for a fleet to drop into a system in one fell swoop, Just to freak out the players, The fleet jump thing is just too good to be let down by rules

 

[Bense]

IIRC this problem was addressed in DGP's Starship Operator's Manual, or possibly an article in The Traveller's Digest. The idea was that the fleet ships could tie their computers together and take longer to plot the jump in exchange for reducing the time variable for each of the jumps to mere minutes rather than hours.
Since everyone arrived within an hour that made coordinated attacks much more viable.

 

[phavoc]

This would only work if the variable was the calculation of the jump itself, rather than some vague and little-understood aspect of jumpspace.

See, now something like this concept belongs in a FLEET sourcebook.

 

[hdan]

This is why fleets jump into the outer parts of a system and wait for everyone to arrive before moving in. (And 6G battleships make this not an unreasonable tactic.)

 

[BP]

Originally played time and location as slightly random (pre-MgT). MgT Core seems to support this notion - '...tends to arrive close to the target world, but outside or on the verge of the hundred-diameter limit.' pg 141.

IMTU, using a 3D variant, time is not random, but does vary by normal hours depending on systems one is jumping between (based on a formula). Time and location accuracy are determined by Effect.

 

[Egil Skallagrimsson]

Sector fleet does suggest a "Squadron or Fleet Jump", certainly for naval ships fitted with appropriate systems.

Not sure I go along with the idea, though can see the arguments on both sides, quite like the problems caused by staggered and only partly predictable emergence times from jump, and the need to consider that in your tactics if planning to launch a major attack, or even move a convoy through several jumps.

Egil

 

[phavoc]

NOT being able to coordinate your jumps opens up a whole interesting can of worms. As someone pointed out, battleriders are quite useful since they are, ton for ton, more effective than a jump-capable ship.

So your system defense forces see a few enemy ships pop into your system. Should you go engage them immediately? What are you going to do when other ships start appearing, or maybe they won't, or... Neither side will really know when someone else is gonna show up to the party, only the attacker knows the guest list.

And then it makes for interesting combats, as your supply ships and fleet train are gonna have to show up eventually, and then begin refueling and resupply operations. But ships that carry large quanties of things that go 'boom!' are best deployed in secured territory. Defense ships equipped with jump drives can do an intrasystem jump and cause all kinds of chaos too. Definitely makes for some interesting scenarios and lots of opportunities for the GM to drop a few "oh craps!" into play.

From a smaller, PC perspective, it lets the GM still play some nefarious tricks on unsuspecting players. Say the players are charged with escorting another ship. Should they jump earlier and stooge around the planned realspace exit point for a day or two, waiting on their client? But if they do that, they leave the same ship vulnerable in the departing system. Decisions, decisions!

 

[far-trader]

As much as the totally random scattered jump vaguely implied (imo) by the rules might be fun in some ways, it's never made sense to me. To paraphrase...

"Traveling through hyperspace ain't like dusting crops, boy. Without precise calculations we could come out too close to a star, and that'd end your trip real quick, wouldn't it?"

The random time and spatial deviation are imo meta-game aspects representing the variances resultant from the precise calculations needed. In-game you know, down to a very fine degree of precision, exactly where and when you will (should) come out of jump, and with just what vector, well in advance of the actual jump. This is supported imo by many other statements and examples throughout Traveller over the years, though I'm not sure how many of them MGT has addressed yet or will. To wit...

This permits the whole retention of vector rule to mean something and be useful. It requires some thought on the part of the players since boosting at full thrust running for the 100d from a size 8 world is going to be a problem on the other end if they plan to come out at the 100d aimed at a size 2 world.

It also allows the use of pre-programmed jump plots. Though of course you have to abide by the very precise jump requirements of the specific ship, the jump initiation point in space and time and the vector, the exact jump distance, and jump destination. Or risk a misjump.

It also means the Black Globe tactic of jumping in under cover of your BG and drifting past defenses to a secret sneak attack point will actually work.

It also matches with the old (paraphrased) "The first indication of a misjump is often the failure of the ship to precipitate at the calculated time, or precipitating before the calculated time."

Which also helps with crewing task, since you don't need to have the stations manned for hours at a time anticipating jump precipitation and being worried about exactly when and where you will end up.

And of course it lets you make coordinated jumps so fleets can plan an invasion beyond "Let's see what things look like when everybody gets there."

In short (too late... ) coming out of jump at a random place and time is just too dangerous. You might end up having to chase after the planet you were hoping to arrive at, wasting time and if low on life support or fuel that could be critical. Or you might end up having to dodge out of the way as the planet races at you from an unexpected vector.

...but I seem to be in a very small minority in my interpretation and expectation of some logic on this point. That's fine, I'm happy here

 

[phavoc]

Oh, I don't disagree with you on that Dan. I think its another feature 'creep' that got into the rules. Just as MgT changed jump travel to hydrogen being used to create a pocket universe instead of being converted into energy and powering your lanthanum lattice work on your hull to get you into jumpspace.

While I know any game master is free to wave their hand and modify the rules, I've always been a big fan of having good rules established upfront and then going on to modify them as you wish. It's just that when the rules don't make sense as published that I start threads like this.

 

[Egil Skallagrimsson]

far trader

Oddly enough the different emergence times make more sense to me, imho, eg, even if two similar vessels use the same co-ordinates, and the same power settings etc, they will not be occupying exactly the same point in space, and very small differences in headings creep in. Then multiply by 3 or more light years transitted in the pocket universe of jump.

(and I like the problems that phavoc indicated, there are ways to get around most of them, but they need different strategies from just everyone arriving in at the same time)

Imho,

Egil

 

[hdan]

In short (too late... ) coming out of jump at a random place and time is just too dangerous. You might end up having to chase after the planet you were hoping to arrive at, wasting time and if low on life support or fuel that could be critical. Or you might end up having to dodge out of the way as the planet races at you from an unexpected vector.

That's why I've been considering adopting the convention that a Jump that ends right at the edge of a gravity well is the most accurate, and what most commercial ships will attempt.

Here's my pseudo-scientific mumbo-jumbo justification:

Since the 100d limit can't really be what pulls you out of Jump space (else the Kuiper belt would prevent jump travel), I imagine that the "end" of the journey, as you approach our Universe again is when the gravity "bumpy-ness" of the fabric of space can begin to affect the ship.

I imagine J-space as being the hyperspace between the two hyperdimensional membranes that collided to make our Universe in M-brane theory. (Or in my fictional version of M-Brane theory at any rate.) J-Drives kick you out of the universe, but super-gravity (the force that pushes the 'branes together) will ultimately push you back into our universe. Gravity wells "stick out" (in my imaginary version of M-brane theory, at any rate) and as you begin to approach the universe, they are "stickier" than flat space. That's why you need to get away from them to jump. It's not impossible to jump into deep space, but due to minor but chaotic fluctuations in the 'brane beyond TL-15 technology to detect, you have a harder time pinpointing your re-entry point. Aiming for an obliging world (or at least star) can help increase predictability.

The ship's inertia relative to the last gravity well is preserved, so you won't find yourself being left behind by jumping to a different orbital distance. Come to rest relative to your departure world, and you'll start at rest (but falling) towards your destination world. A very clever navigator could possibly compute an outbound vector that would allow easy inbound orbital insertion (shaving time off your approach if you intend to orbit) but that would require excellent charts and instrumentation, and is still subject to the minor perturbations introduced by the chaotic nature of Jump space.

Sure, it's all hooey, but it makes a kind of sense in my brain at any rate.

 

[locarno24]

Since the 100d limit can't really be what pulls you out of Jump space (else the Kuiper belt would prevent jump travel), I imagine that the "end" of the journey, as you approach our Universe again is when the gravity "bumpy-ness" of the fabric of space can begin to affect the ship.

Even with objects producing 100D "bubbles", is the Kuiper belt really that dense?

 

[silburnl]

Even with objects producing 100D "bubbles", is the Kuiper belt really that dense?

No. Space it too big for the 100D limit to create effective linear (toroidal?)barriers to Jump-ing ships.

 

[phavoc]

I think the way the jump rule is written is too tight. I would say that an object with mass has to be X times more massive than you to pull you out of jump space. A star? Sure, I get that. A gas giant, or a planet with say .25 standard masses? Yeah, I can go along with that as well. But a 500m diameter space station? No. Your external jump tanks? Um, hell no?

Systems are going to have billions of objects floating within them. Systems with large asteriod belts would be a nightmare to enter/leave, especially if these system had objects floating in a shell rather than on the elliptical plane. And there are also (as was pointed out) many more objects in the kuiper belts.

Jump travel is better off plotting to avoid large, known stellar objects. I'm ok with the jump rule as written (random popping out of jumpspace), but it goes against the previous Traveller rule books where they talk about fleet actions and such. Changing the jump rules from lanthanum jump networks in the hull to a pocket universe populated by exotic particles derived from hydrogen is a relatively minor change. But fundamentally changing jumping to make it impossible for two ships to arrive/depart at the same time is a huge change. If you (i.e. MgT) is going to do that, you need to dedicate FAR more text in the rulebooks than what is listed. I am wondering how much thought went into the change, or if any was given, to all the possible ramifications.

I would also think that most ships arriving and departing a planetary system or body are going to using above/below the system's eliptical plane, since there should be fewer planets and large system objects in their way for their jump navigation.

 

[BP]

I think the way the jump rule is written is too tight. I would say that an object with mass has to be X times more massive than you to pull you out of jump space. A star? Sure, I get that. A gas giant, or a planet with say .25 standard masses? Yeah, I can go along with that as well. But a 500m diameter space station? No. Your external jump tanks? Um, hell no? ...

Good points, but actually, the rules as written aren't overly 'tight':

• 'A ship can only safely Jump when it is more than one hundred diameters distant from any object.'
  'Gravity can cause a Jump bubble to collapse prematurely...'
  '-8 if still within the hundred-diameter limit'
  - Core pg 141

There is some wiggle room in those statements and the mechanic implies that the 100D is not absolute. (CT had +15 for 10D and +5 otherwise when within 100D).

As to the 100D and mass of objects precipitating one out of Jump - the odds of coming within 100D of a smaller, unplanned for object, is extremely tiny. Having to make allowances for asteroid sized bodies and above accounts for the Jump Plot time. Mis-jump skill check accounts for the fact that not everything will be accounted for.

For jump away from 'drop tanks' - mere fractions of a second would normally cover separation distance. A space station is typically within 100D of a planet, but even if it weren't, 50 km from a 500m diameter one might sound far - but that is nothing compared to orbital speeds (i.e. solar orbit). From the standpoint of precipitating dropping out of Jump - a 100 km dia bubble is also nothing compared to the volume of space in a stellar system.

MgT is based on CT and does not fundamentally change the variable time for jump - CT HG stated - 'approximately one week (150 to 175 hours).'

My original take in CT was that the time variable was a game mechanic and in-game, the PCs would have a very accurate time of arrival - as far-trader suggested earlier. My read from the Traveller community over the years is that this is largely considered a random in-game thing. Personally, I prefer my jumps fairly accurate (as mentioned with a formula for a 3D version - with some seconds/minutes of variation normally based on task check).

 

[Rikki Tikki Traveller]

References would be nice. I have yet to find any references in the MGT rules that cover jumps. Astogation checks will get you to where you want to go, but as far as I can tell, the rules state that jump travel varies at the SHIP level... ergo no matter how accurate your jump estimates are, each ship will pop out of their pocket universe with a random time factor of 6d6 (6 - 36hrs).

An explanation of jump travel is not even listed in high guard that I recall.

I think you are reading too much into the basic rule in the TMB. It does not SPECIFICALLY state that the variation is PER SHIP within a Fleet. In fact, the rules say NOTHING about fleet jumps. That section of the rules is talking about a single ship going through the jump process.

This is one of those HOT TOPICS amongst the old guard. LOTS of discussion but no real good rules definition. MegaTraveller MAY have had something about it in the Starship Operations Manual (if you can find it), but that is about it.

This rule is completely subject to Referee interpretation. HOW and WHY there is that varfiation in the time of jump is never explained, only that it exists. A Referee is free to come up with a reason and that reason would determine how a fleet trying to jump together would react.

I am not aware of any OTU setting rules that specifically discuss fleet jumps, however, within the history of the setting there are numerous references to fleets jumping into a system and catching the locals by surprise. So at some level Fleet Jumps are allowed (and used) within the OTU. Make of that what you wish.

Back to MGT, the rules state that the ship forms a pocket universe which is inflated with Hydrogen and the ship moves into that. The question for a Referee is: If two ships are close enough, can they "share" a pocket universe? IF you say YES, then fleet jumps are possible in that situation, if you say NO, then probably not; but again, it goes back to what causes the variation in the time of a jump. It is not explained (at least not within MGT rules), so YOU have to decide for your game.
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