Can a fleet of ships "jump" together?

[ak_aramis]

Bill's "dodge" of the literal wording is how I've always read it. Everyone arrives within the same ±100 minute pane of a ±1008 minute arrival window.

[Sumner Kai]

Even better. Thanks all.

[Hans Rancke-Madsen]

Originally Posted by ak_aramis

Bill's "dodge" of the literal wording is how I've always read it. Everyone arrives within the same ±100 minute pane of a ±1008 minute arrival window.

I've never heard that suggestion before. It sounds like a workable way to implement it.


Hans

[JCD]

Mmm...space is big.

So why not just have the ships arrive a ways out? There is no way that whatever defenses a system has can cover all the approaches to a planet if spread out.

So if you see A destroyer appear at 3 a.u., the question you need to ask yourself as the defending leader is 'can I get enough forces there to destroy it before the Tigeress Dreadnaught shows up or not?' YOU can't arrive piecemeal either.

Not to mention, a few 'decoy' signals. You hear a 40,000 ton jump sig from two locations. Unless you have someone close by, how can you tell the 'decoy' tanker(s) from the destroyer group which is coming into your system?

[Sumner Kai]

Agreed, plotting a jump-arrival point for a fleet of warships intent on mischief could be as simple as "Pick a point a long way out, wait for everyone to arrive, form up and burn in."

But...

What if more tactical surprise is desired than 35+ hour arrival window and then a long voyage in-system?

Besides, if I were going to jump my fleet to a system so far out that the defenders could not respond w/i 35 hours anyway, why not go a little farther out? Then, I could form up, burn in for a bit, and then go quiet and ballistic, off of their scopes until it is too late...

...ignoring the debate concerning heat and all that...

[JCD]

I think that attack and defense get very complicated in space combat.

For example, I can see a 'big board' with the star system on it with 'shadows of 100 D placed for reference. "Well, Mars is in Transit so we don't need to worry about anyone coming in from Galactic East from 45 degrees to 86 degrees without giving us a chance to get our defenses mustered."

Which is the other side of the coin: How did the defenders deploy? Did they keep 'One Big Fleet' around? If so, the chances of it being in position to burn in in less than 8 hours seems problematic.

Is the timing of a jump statistically random i.e. one is just as likely to arrive 16 hours early as it is to arrive 16 hours late? Or is the arrival time in a bell curve, with most of the arrivals happening within a 3 hour window with a diminishing chance of a VERY late arrival?

If the bell curve is the case, then there is very little need to worry TOO much about having enough ships in the first few hours. Most of them will be arriving VERY shortly. That might have been one of the reasons for the early use of the battle rider ships: their navigational techniques weren't sharp enough to guarantee arrival times, so they essentially sent is a 'fleet' in one bundle.

The other question NOT asked is one of 'arrival accuracy'. Will the ships arrive right next to one another just like they departed or is there a 'random element' which might put them up to an a.u. apart?

[Anaraxes]

Originally Posted by JCD

Is the timing of a jump statistically random i.e. one is just as likely to arrive 16 hours early as it is to arrive 16 hours late? Or is the arrival time in a bell curve, with most of the arrivals happening within a 3 hour window with a diminishing chance of a VERY late arrival?

Pedantry: For the first case, you probably want the word "uniform" (same probability for all events). The bell curve is also "statistically random". It's just a different kind of random distribution.

Any of the rules that use more than one d6 to determine the arrival time become somewhat bell-ish. 1d6 is uniform. Adding up many uniform distributions* ultimately becomes the bell curve.

--
* Or any other distribution, for that matter.

[Bill Cameron]

Originally Posted by JCD

The other question NOT asked is one of 'arrival accuracy'. Will the ships arrive right next to one another just like they departed or is there a 'random element' which might put them up to an a.u. apart?

It hasn't been asked because it was definitively answered over two decades ago in Marc Miller's jumps space essay in the original JTAS magazine.

Jump's physical accuracy is 3000km per parsec jumped. Your actual exit point, as measured from the departure system, is within a 3000km sphere of your plotted exit point. Of course, the temporal deviation involved will place that actual exit point at varying distances from the various bodies within the arrival system, however, when measured from the departure system you arrive somewhere within 3000km of your plotted exit per parsec jumped.

[JCD]

Originally Posted by Bill Cameron

It hasn't been asked because it was definitively answered over two decades ago in Marc Miller's jumps space essay in the original JTAS magazine.

Jump's physical accuracy is 3000km per parsec jumped. Your actual exit point, as measured from the departure system, is within a 3000km sphere of your plotted exit point. Of course, the temporal deviation involved will place that actual exit point at varying distances from the various bodies within the arrival system, however, when measured from the departure system you arrive somewhere within 3000km of your plotted exit per parsec jumped.

Silly me for not having bought every single Traveller based magazine.

Thank you for the update.

[Fred Brackin]

Originally Posted by JCD

Which is the other side of the coin: How did the defenders deploy? Did they keep 'One Big Fleet' around?

If you have only one major target to defm3ed (such as your mainworld) then you keep just the One Big Fleet.

The gymnastics of intercepting a enemy incoming at a constant accel (or decel) are involved enough you don't station far from the target world.

For example, if the Opfor is 8 hours away at 4Gs you accelerate outward on the proper vector for 1 hour. Then you flip and decal for 1 hour. then you turn 180 degrees at accel toward the mainworld for another hour.

At this point if you've done your navigation right and the Opfor hasn't done something to complicate your life both fleets should be 1 hour away from the target world at constant decal and you are hopefully within range to begin shooting at them without whizzing past.

This is about the simplest intercept possible. Things could be much more complicated. It's quite possible you could decide to just park your ships in the enemy's path and wait for them to come to you, hopefully out of bombardment range of the world you're defending.