OK I read somewhere in the forums in the last couple of days about military ships being able to control the duration of the jump they take. Which makes it possiable for a fleet to leave and arrive at basically the same time. That is all well and good, as having your fleet arrive 1 at a time seems pretty much tantamount to suicide as the potential for a waiting fleet to blow each ship up as they arrive is very real in a conflict. Now for my question does a ship entering Jump have to be facing the target arrival area. meaning if you jump and I will just use 1 solor system jumping as an example for clarity sakes. Jumping from Earth to Mars does the ship have to face Mars or could Mars be to the ships side or rear. I ask this as I was thinking that if you had to face the direction you were gonna jump, it would be a major disaster for an entire fleet to jump and all of them arrive with a Defending fleet waiting for them from behind. All ready to fire everything up the bum so to speak. I feel that jump should not matter a ship's facing, as a fleet jumping into a possiable combat zone would want all guns facing out in all directions then not all guns would need to be brought into bearing for the conflict only a percentage which would be based on fleet make up. Another question I just thought of what about mining potential arrival points ships jump in and hit mines and bang 1 less ship. I mean the idea of being able to mine an entire solor system could not be done but mining key arrival points could work for some systems based on positions.
Jump Direction and Timing
- Thread starter Jacqual
- Start date
far-trader
SOC-14 10K
Well, yes you can coordinate jumps between multiple ships to allow them to come out more or less together. I've always read it not as controlling the time in jump but controlling the entry parameters so that the time spent in jump is the same for all ships. This fits my theory that time in jump and eventual point of precipitation is not random (the random rolls are game artifices) but well predicted. It has to be imo. So you can know, for a given set of parameters, exactly how long (to a very precise degree) a jump will take, and exactly (again with high precision) where the jump will come out. It just HAS to be that way for it to work the way it is described imo.
So, extending my personal view (based I think on the best logical take on canon) to your questions...
Does a ship entering Jump have to be facing the target arrival area?
In a manner of speaking, yes. Jump space maps to normal space, compressed by time in a fashion. So the orientation you set the jump up with is carried through jump. This is required for the canon practice of preserving your vector through jump space.
However you have to account for the time difference. If you point your ship at Mars from Earth and jump, a week later you'll come out of jump pointing right at where Mars was a week ago. If you want to come out of jump pointing right at Mars you have to calculate where it will be in a week and aim for that.
Personally I don't think you can orient a ship to come out in any facing but nose on in the direction of the point you are jumping too. That point could have you looking directly at Mars, or to the side of Mars, or even with Mars behind you. But your vector will be the same in each case, right ahead.
For a defending fleet to be able to ambush you would require knowledge in advance. A tricky thing to do when jump takes a week. You'd have to have a spy learn of the plotted jump and then make their own jump far enough ahead of the enemy to arrive first with time to organize the defense fleet in the proper place. Not impossible, but far from easy. And very easy to counter by holding the final jump plot until the last few minutes.
Another question I just thought of what about mining potential arrival points?
Another good question. The problem there is in canon there are no limits on where a ship can arrive at. Only limits on where it cannot arrive (i.e. within 100 diameters of any planetary body)
So you have to mine based on covering the 100d range of potential targets, and even then that only gets the ships trying to come out right there. If they come in at 150d then they just need to be careful in clearing the minefield before proceeding.
So, extending my personal view (based I think on the best logical take on canon) to your questions...
Does a ship entering Jump have to be facing the target arrival area?
In a manner of speaking, yes. Jump space maps to normal space, compressed by time in a fashion. So the orientation you set the jump up with is carried through jump. This is required for the canon practice of preserving your vector through jump space.
However you have to account for the time difference. If you point your ship at Mars from Earth and jump, a week later you'll come out of jump pointing right at where Mars was a week ago. If you want to come out of jump pointing right at Mars you have to calculate where it will be in a week and aim for that.
Personally I don't think you can orient a ship to come out in any facing but nose on in the direction of the point you are jumping too. That point could have you looking directly at Mars, or to the side of Mars, or even with Mars behind you. But your vector will be the same in each case, right ahead.
For a defending fleet to be able to ambush you would require knowledge in advance. A tricky thing to do when jump takes a week. You'd have to have a spy learn of the plotted jump and then make their own jump far enough ahead of the enemy to arrive first with time to organize the defense fleet in the proper place. Not impossible, but far from easy. And very easy to counter by holding the final jump plot until the last few minutes.
Another question I just thought of what about mining potential arrival points?
Another good question. The problem there is in canon there are no limits on where a ship can arrive at. Only limits on where it cannot arrive (i.e. within 100 diameters of any planetary body)
So you have to mine based on covering the 100d range of potential targets, and even then that only gets the ships trying to come out right there. If they come in at 150d then they just need to be careful in clearing the minefield before proceeding.
Oh cool, I get to use my new GURPS Traveller PDF that I just got:
So it depends on your game system for Traveller...
The first one indicates the ship is standing still and enter's jump space, which means it exits with the same vector and accel. Pretty easy.
The 2nd one seems to indicate that the ship just (as in only) has to decelerate, not turn around which is what happens in Book 2, you move, turn around at midpoint and thrust back the other way to stop.
So it might involve how much you're willing to read into it.
I'd say you can pretty much do what you're suggesting. I'd like a ref on the "military ships can regulate time in jump" just to be handy. What I've considered was that for fleet or convoy ops, one ship calcs the jump for all those involved, disperses the info, it's double-checked then used by all ships to make them arrive in unison.
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So it depends on your game system for Traveller...
Code:
Standing Jump: A standing jump attempts to give the emerging ship an
orbital vector at the destination system. (Note that this will almost certainly
require a non-orbital vector at the departure sytem.) Usually this is the safest type
of jump, since it minimizes the possibility of colliding with a random asteroid or
such. (Accidents still happen, which is why most starships have some armor.)
Running Jump: A running jump attempts to position
the ship such that it need merely decelerate to
approach the destination world. If poorly calculated, the
ship will be off course and can waste considerable time
maneuvering to the world.The 2nd one seems to indicate that the ship just (as in only) has to decelerate, not turn around which is what happens in Book 2, you move, turn around at midpoint and thrust back the other way to stop.
So it might involve how much you're willing to read into it.
I'd say you can pretty much do what you're suggesting. I'd like a ref on the "military ships can regulate time in jump" just to be handy. What I've considered was that for fleet or convoy ops, one ship calcs the jump for all those involved, disperses the info, it's double-checked then used by all ships to make them arrive in unison.
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CosmicGamer
SOC-14 1K
You need probably half a sphere surrounding the location if you know where the enemy is jumping from. [That sound right? I don't think you can jump 'through' the planet without hitting 100d and leaving jump space.] Even half a sphere at 6780 km (4213 miles) in diameter (your example of Mars) is LOTS of mines.
As hinted at (jumping to where Mars will be in a week) the location where you are jumping to also has an orbit so if you suround the planet Mars at 100d with mines, the planet will run into the mines unless the minefield somehow orbits the planet or has the same orbit as the planet so that it moves with it.
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My own take on time in jump is that a jump takes 7 days - that's 7 x 24 = 168 hours to the second. 1st ed has nothing about time in jump being variable. 
The second part, based on Asimov since 1st ed is blank on the subject, is tyhat the ship's vector is preserved. The vector, is of course, relative to the galaxy, not to any star system.
The third part, based on the 100 diameter rule, is that applies equally - as IMO it must - to the star. You won't be jumping from Earth to Mars because both are within the 100-diameter limit of the Sun.
YMMV
The second part, based on Asimov since 1st ed is blank on the subject, is tyhat the ship's vector is preserved. The vector, is of course, relative to the galaxy, not to any star system.
The third part, based on the 100 diameter rule, is that applies equally - as IMO it must - to the star. You won't be jumping from Earth to Mars because both are within the 100-diameter limit of the Sun.
YMMV
CosmicGamer
SOC-14 1K
The sun is approx 1,390,000 kilometers in diameter. 100 x 1,390,000km = 139,000,000kmMy own take on time in jump is that a jump takes 7 days - that's 7 x 24 = 168 hours to the second. 1st ed has nothing about time in jump being variable.
The second part, based on Asimov since 1st ed is blank on the subject, is tyhat the ship's vector is preserved. The vector, is of course, relative to the galaxy, not to any star system.
The third part, based on the 100 diameter rule, is that applies equally - as IMO it must - to the star. You won't be jumping from Earth to Mars because both are within the 100-diameter limit of the Sun.
YMMV
The Earth travels around the sun at about 149,600,000 kilometers.
Ref: http://www.nasa.gov/worldbook/sun_worldbook.html
149,600,000 > 139,000,000
Unless the data I got from NASA and other sources is wrong or I am interpreting something wrong, Earth and Mars (farther from Sun than Earth) are outside the 100d range of the Sun.
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The Oz
SOC-14 1K
I think you are correct in this. A ship's facing (where its nose is pointing) is separate from its vector (what direction the ship is moving). A fleet jumping could set up their vector to carry them the direction they wanted after exiting jump, then rotate their ships to cover all angles (if they wanted to) and then jump. The fleet would emerge from jump in the same positions and facings (relative to each other) as when they entered jump.
IMTU, of course....
Unless you jump to somewhere in the system that you're pretty sure is outside the weapons range of any defenders. You then wait for your stragglers to arrive, form up, and move towards the defenders, who has had up to 34 hours warning (but probably a bit less).
What attacking fleets can do is spend a lot more time calculating the jump and thereby reduce the jump duration uncertainty from +/- 17 hours to +/- 2 hours. In which case the defenders have only 3 hours warning -- plus the travel time from your arrival point to your target.
No. You just arrive with the same heading and vector as you left the departure system with.
Hans
I disagree. That is, I agree that the way a jump is described is a game artifice, but I believe the simplification lies elsewhere. A ship that jumps to a destination world aims for where that world will be in 168 hours. Say the destination world moves 100 diameters in 14 hours. That means that if the ship arrives at any time between 154 and 182 hours, the ship will be precipitated out somewhere along the planet's 100 diameter limit. If its vector is neutral with respect to the destination world, the ship will act exactly the way it is described. Only if it arrives in less than 154 or more than 182 hours will it not. So, assuming that jump variation follows a bell curve, a very large proportion of jumps will arrive at the jump limit. The simplification is that the game rules ignores the low-probability outcomes.
Hans
Orbital Assault
SOC-1
fleet formations
Actually I remember asking same question a very long time ago (B.I. [Before Internet] and to really arriving at an answer. However, to extrapolate your suggestion further, because the location of the potential enemy at the destination of fleet jump is unknown, the fleet would have to try and cover every direction, and therefore jump in a formation that would be a sphere, right? However, as I remember sensors are not unidirectional, so acquiring targets at Jump destination would be irrespective of facing direction, and having any percentage of the fleet face in the right direction (how does one calculate that?) would only matter if the number of ships facing is greater or equal to in weapons than the enemy.
Doesn't really answer your original question of post-Jump facing direction though....
Cheers
Actually I remember asking same question a very long time ago (B.I. [Before Internet] and to really arriving at an answer. However, to extrapolate your suggestion further, because the location of the potential enemy at the destination of fleet jump is unknown, the fleet would have to try and cover every direction, and therefore jump in a formation that would be a sphere, right? However, as I remember sensors are not unidirectional, so acquiring targets at Jump destination would be irrespective of facing direction, and having any percentage of the fleet face in the right direction (how does one calculate that?) would only matter if the number of ships facing is greater or equal to in weapons than the enemy.
Doesn't really answer your original question of post-Jump facing direction though....
Cheers
