Jump Bubbles

[phavoc]

Yeah, get rid of microjumping. Who really uses it anyhow and assume the drives are optimized for interstellar distances rather than inter solar.

If your destination is more than 7 days away in N-space, then jumping (assuming you have jump drive) is faster. I would say normally there would probably either need to be a very big need to get somewhere as fast as possible or that the destination is say around 9 days or greater in distance before a jump would be used. N-space might take a day or two longer, but you'll save a lot of potential fuel using your normal maneuver drives to get there.

No. There are PP's that are fission. Fission has ALWAYS been part of Trav. From '77 on.

Cite pages in the 77 edition that are not just trade goods, please.

Also keep in mind that the 77 edition is prior to the setting in any form.

Sorry, I missed this post. Um, for those who are new to Traveller. (didn't play the original version or weren't born yet) I believe that you'll find that FISSION PP's will most likely be listed in the LBB #3 under world generation, TL descriptions column for power sources by TL.
[/quote]

I scanned through the original Trav books #2, #3 and High Guard. There is one mention of fission in book #3 in relation to what TL fission is available as an energy source, but all of the original Trav books have fusion as the only power plant available for starships. I have the FFE DVD's so a keyword search is pretty fast.

 

[Reynard]

Okay, I did this in an earlier post and I'll do it again.

Book 3, on page 11, mentions fission fuel at TL 6. That's the age of nuclear subs and aircraft carriers. Non-starships begin at TL 7 and we know, at least in our reality, that atomic engines aren't launching or propelling spaceships. At TL 8 the Traveller universe has fusion for power and this is followed by starships. The drives are fusion not fission. Even air/rafts become available at TL 8 with the development of fusion and contra-grav that will move space and star ships.

Page 44 of Book 2 lists trade goods. I mentioned there was only a vague 'cargo' unit in a previous post but discovered this reference. I think I misread that when it referred to a quantity of a particular trade good. Radioactives are a commodity with no specific use and could be medical to power. After that there are no nuclear power plants for sale. I have a feeling you ship the parts to be built permanently on site.

No starship atomic power plants, Flash Gordon.

 

[sideranautae]

I scanned through the original Trav books #2, #3 and High Guard. There is one mention of fission in book #3 in relation to what TL fission is available as an energy source,

Correct. It lists at what TL's and later fission is a power source. Weird that someone thought that fission wouldn't be a power source in a high tech setting when its profile would make it the only logical choice.

 

[Bardicheart]

Hmmm, not so sure I would agree. I do agree the time that passed for the crew would seem like 148+6d6 hours, that part of the rules is pretty clear.

The rule is, Jump only 6 inches (in system jump) and it takes 148+6d6 hours. Jump 1 parsec and it takes 148+6d6 hours.

You need to restudy the rules.

Really... re-read what you quoted. I agreed with that part.

 

[Bardicheart]

This is the part about misjumps that I was referring to (from CR p141)

Misjumps
On rare occasions, normally because of a lack of maintenance or
using unrefi ned fuel, a ship can misjump. Some misjumps are lethal,
causing the Jump bubble to collapse early or for time in the bubble
to fl ow differently, so that trillions of subjective years pass inside the
bubble and all that comes out the other end is hard radiation caused
by protons exceeding their half-life. A merciful Referee, though, may
wish to subject his players to the most survivable form of misjump,
where the ship ends up 1d6 1d6 parsecs in a random direction.

I bolded the part specifically important. According to that it is possible the time in the jump takes longer, potentially much longer than the normal 148+6d6 hours. However, I also had misread that previously and was operating on the belief that time outside the bubble would pass while time inside the bubble remained about 1 week. That appears to be in error though I'm thinking there was a reference elsewhere to that effect. I can't recall where right now though, will look for it.

Hope that clears up any confusion.

 

[Condottiere]

Microjump: dead slow elevator.

 

[Meanderer]

From early in this topic:

One big reason to slow down or even stop before jumping you don't know what's in the region of the destination you enter. Space is big but there's still stuff out there. You won't have much reaction time if you come screaming out of the tunnel blind plus you might not be aiming toward your final destination.

I think slowing down or stopping isn't that big a deal because pretty much every item in the star system is moving relative to the star system and at a considerable velocity.

In the Sol system, Terra is moving approximately 30 kilometers per second. If you come out of jump in its path, no problem. At 100 planetary diameters it will take the planet about 12 hours to reach you and you can accelerate at 10 G's and get out of its way in about 20 minutes.

But that is because the distances are so huge. Now let's imagine you came out of jump because you came within 100D of a 20 displacement ton asteroid travelling at 10 kilometers per second.

That 100D is just 800 meters (assuming a spherical object 20 tons in size - works out to a diameter of 8m). So that asteroid is going to cross the distance and hit you in just 0.08 seconds. I doubt anyone is firing up their maneuver drive that fast to get out of the way and if you can accelerate to 10 m/s/s in one second, then doesn't that mean accelerating to 0.8 m/s/s in the time it will hit you? Considering the rock is 8 m in diameter, that isn't going to help you much getting your whole ship out of its way.

Of course if you are moving in its direction any velocity you have is only making things worse. But I think that coming in with zero relative velocity isn't necessarily making things safer. The primary protection is that space is pretty empty and the chance of such a forced emergence is low.

Also, if jump points are influenced by the gravity of nearby objects, then would being stationary relative to the star but moving relative to the planet have an impact? Maybe that is why 100 diameters is so important and there are penalties for being closer to the planet - but you are going to be moving relative to gravity sources because they are moving relative to each other.

I always allowed ships to be moving. The jump drive creates a gate inside the jump drive between the ship and the jump bubble and because the jump drive is holding this gate open the gate will move relative to the jump drive.

This keeps the ship from being a sitting duck while plotting a jump. The jump drives can be spooled up and jump course plotted while the ship is still in motion. Goes from an hour to make the jump down to a few minutes - but you still have to go through that preparation time and still need to cross the distance from the planet to a safe jump position. Allows emergency jumps on the way out (at say just 20 planetary diameters) if being attacked - taking chances with a misjump. Otherwise, if you have to stop and wait - why stop at just 20 diameters out?

 

[Meanderer]

This one is easy. If you aim for a planet but hit its 100D mark before you reach the planet how long are you in jump? 148+6d6 hours. Leaving jump because you reach a gravity well is considered a "normal" exit. No danger. Just use the same time period because a micro-jump uses the same time period. Deliberately ending a jump by sucking the hydrogen back into the ship (or whatever other creative means one uses) is a mis-jump situation. Roll on a table or let the GM take out his pent up aggression... :twisted:

Agreed. Ships don't misjump because they come into proximity with a gravity source they just re-emerge into normal space. I figure this is how some rogue planets and comets within the great rifts have been plotted. Trying to make a jump 5 across a great amount of space but only making it jump 2 before re-emerging 100D out from a chunk of rock in deep space. If you are lucky this chunk of rock has a high ice content where you can refuel to continue your jump (and plot its location for future reference as such a deep space refueling point could have strategic or economic importance.

But if you are coming out as much as 15 hours early or late the planet you are aiming for is no longer (or isn't yet) where you thought it was. If you were aiming for our solar system for an emergence near Terra, arriving 15 hours off means Terra will be 1.6 million kilometers distant from where you expected it to be (around 7 hours at 1G)

I find this great variability on emergence is important if we allow ships to maintain their velocity in jump (which I think we reasonably need to do). It doesn't take long for someone to realize that a ship jumping in at a significant velocity can do a lot of damage hitting a planet. Consider an old Lightning class cruiser that is near the end of its useful life and is turned into a missile. Twenty-seven hours of acceleration would give it a velocity of around two thousand kilometers per second. Assuming that 60,000 displacement tons equals a mass of 60 million kilograms, this ship would hit with a kinetic energy equivalent of more than 28 gigatons of TNT. That is more than ten times the total explosive force that would be unleashed by detonating the entire nuclear arsenal of the USA. Not going to crack open a planet, but that amount of energy hitting an atmosphere will have catastrophic effect. But the variation in arrival time means you can't reliably put it on a vector to hit the planet before you jump.

Kind of drills home the awesome power of just throwing rocks at a planet if velocity is enough. A 50 million kilogram rock accelerated at 6 G for one day will have a kinetic energy equivalent of 161 gigatons of TNT.

Makes me wonder how others have dealt with such destructive force and rationalizing why navies aren't planned around making such attacks on enemy worlds? Or are they in your Traveller universe?

 

[sideranautae]

I find this great variability on emergence is important if we allow ships to maintain their velocity in jump (which I think we reasonably need to do).

I don't allow inertia to transfer from one dimension to another. Different referential frames. Solves a lot of problems in the game. I could go either way but I chose that way just to simplify the game a bit.

 

[GypsyComet]

Microjumping still has its uses. A scale shift might be illustrative.

Some of you may remember the Judges Guild overland mapping system (http://www.judgesguild.com/downloads/index.html near the bottom), in which one of the big map hexes would become a full page display, covered in smaller hexes. The big hex was 33 of these smaller hexes across, allowing you to map in more detail.

Apply that to a subsector map. One hex now has several hundred smaller hexes nested within it, each one just about 0.1 light years across. Our entire Solar System still fits into ONE of these smaller hexes unless you include the farthest identified trans-Neptune objects. Even those are only in the next ring of hexes.

In fact, you can take that small hex and apply the 33:1 expansion to it, and seven of the eight planets will still fall within one of those even smaller (1089:1) hexes. Sedna, at nearly 1000AU from the Sun, is riding the edge of this map at aphelion.

That leaves a lot of territory within range of a "micro" jump. It is beginning to look like every one of those 33:1 hexes will have a rock or two in it, and many will have planet-sized rogues.

 

[sideranautae]

Microjumping still has its uses. A scale shift might be illustrative. <snip>

For sure. Our Ort cloud goes out to almost a light year. There will be binary & trinary systems with multiple sets of planets that are ~ ly apart. That's micro jump territory.

 

[Meanderer]

Micro-jumps may also have a tactical role. Have a force of fleet intruder cruisers (high jump capability, heavy missile load) jump in on a high speed vector to skim near a planet. If they are up to around 400 km / second, they can cross the weapon range of any satellite defense systems in about 4 minutes (less than one combat turn). With a good vector and this velocity, their maneuver drive can be used to alter the vector based on how far off the planned arrival time the cruisers arrive in-system. Whipping past the planet (and perhaps any defense vessels as well) at this speed, defenders may only get in one shot before the cruisers are out of range. (perhaps a few shots with missiles). The Cruisers will get a few volleys of missiles on their own against orbital facilities (and perhaps planet based targets as well).

With a great speed advantage missiles fired after them won't be able to catch up and 3-4 combat turns later the cruisers can be outside of the 100 diameter limit and can jump - but where.

(the key feature of a fleet intruder, like the Lightning Class cruisers, is its high jump. With Jump 5, it is possible to jump into a hostile system 2 parsecs away with sufficient remaining fuel to jump back without refueling.)

But what if you lost fuel in the exchange of fire when you skimmed past the hostile world, or if this isn't a full raid but an attempt to soften up the defenses before a larger task force arrives. The cruisers will need to get away from the planet and its defenses but will want to stay in the system to rendezvous with the main fleet or to refuel before attempting a larger jump home. The solution: a micro-jump further out in the system (could be to an outer gas giant or to a comet).

 

[sideranautae]

Micro-jumps may also have a tactical role. Have a force of fleet intruder cruisers (high jump capability, heavy missile load) jump in on a high speed vector to skim near a planet. If they are up to around 400 km / second, they can cross the weapon range of any satellite defense systems in about 4 minutes (less than one combat turn).

At 400 k/s you are about 1 hour from an Earth sized planet (starting from the 100 D area)... Plenty of time for the planetary based, Meson spinals to draw a real good bead.

 

[GypsyComet]

At 400 k/s you are about 1 hour from an Earth sized planet (starting from the 100 D area)... Plenty of time for the planetary based, Meson spinals to draw a real good bead.

Depends on the mission. Meson guns have a shorter range than PA for a given size, and a hit-and-run mission should be going after orbital elements (or testing responses for intel purposes) in most cases. Ground assaults are a very different mission precisely because the ground is such a handy place to mount lots and lots of defensive weaponry.

I'm just glad no one in this setting, with the possible exception of the K'kree, practices the Albedo style of planetary assault. Near-C shotguns are really hard on the real estate...

 

[Meanderer]

Well, most species have experiences fighting themselves and don't survive as a species without developing some sort of surrender reflex and a concept of limited conflict (war waged with some lines you just don't cross). Not to say humans have never waged total war, but we often wage something less than this.

Chemical or biological weapons may be kept as a threat but it is the sort of threat that once you use them you will be in a total war situation. Not so easy to negotiate some cessation of hostilities after you go to far.

That is what makes the K'Kree so crazy dangerous. They don't see the same lines that others do.

 

[sideranautae]

At 400 k/s you are about 1 hour from an Earth sized planet (starting from the 100 D area)... Plenty of time for the planetary based, Meson spinals to draw a real good bead.

Depends on the mission. Meson guns have a shorter range than PA for a given size, and a hit-and-run mission should be going after orbital elements (or testing responses for intel purposes) in most cases.

??? I'm talking about incoming ships NOT being able to surprise and get the jump on a planet. Meson, PA, whatever. That ships are NOT coming out of jump and surprising a planet. The planetary defenses will have more than enough time to ready a ship disintegrating welcome. Given it is of comparable ability.

In other words, you can't pull off Taranto type op.

 

[Meanderer]

At 400 k/s you are about 1 hour from an Earth sized planet (starting from the 100 D area)... Plenty of time for the planetary based, Meson spinals to draw a real good bead

The same could be said of any forces approaching each other at any speed from a distance. Time to prepare.

The fleet intruders don't need constant thrust to maintain that 400 km/s. So their full thrust can be directed in any direction enroute and their effective velocity will still be pretty much the same. It is the same as a slower moving ship maneuvering to evade fire as it comes into range and attacks a target. The difference is that massive velocity difference takes the cruiser out of range within a turn while the slower moving ship will still need to maneuver and evade fire.

Meanwhile, a missile launched in advance of coming into range will be well ahead of the cruisers.

For example, a missile capable of 5G acceleration over 4 combat turns might be launched to travel for 45 minutes before coming into range of the defensive positions. These missiles would be travelling at 525 km/s and about 73 thousand km ahead of the cruisers. Unless intercepted they will hit the orbital facilities before the cruisers come into range. And since we are talking about missiles launched three turns before the cruisers have come into range, there should be at least two more volleys of missiles coming in behind them.

Orbital facilities will be particularly vulnerable as missiles coming in that fast may be very hard to intercept considering they are continuing to maneuver. They would be at a penalty to hit a ship that is maneuvering and would get just one chance to hit (it's speed is too great for it to come back and re-engage) but the same would apply when attacking the fleet intruders as they pass by. Proximity hits might be equally ineffective. You would need a direct hit.

To be clear. I wasn't claiming the enemy planetary defenses would have no means to attack. But they would be firing at a maneuvering ship that will probably have already launched its missiles and would be dedicating all its efforts to maneuver/evade and intercepting missiles coming in. The lightning class cruisers, capable of only 2G would likely have their fighters launched and screening the cruiser from missiles trying to intercept because they are particularly poor at maneuvering. But that said, they aren't stationary targets.

You may plot where it will be on its current vector, for example, but if it turns the direction of thrust 45 degrees to any side for 5 seconds, it will be 175 m to the side and about 75 m behind where it would have been if it had stayed on course. This is for a ship just 61.2 m wide. And that assumes it stays on a constant course for those five seconds.

Space is big and the cruisers would have the same defensive abilities as if they engaged the enemy craft/stations in regular combat. In Traveller space combat your speed doesn't make you any easier or harder to hit, it is the rate in which you are changing speed and direction (maneuvering). But an argument can be made that if you are crossing the entire range of an enemy's weapons in about 1/4 of a combat turn and are maneuvering such that the enemy cannot predict where you will be more than seconds in advance, there should be additional penalties to hit the cruisers. (and additional penalties if the cruisers want to try to fire their own spinal mounts on any enemy ship. It is all happening too fast.

Of course if you have missiles capable of holding off the initiation of their burn (and why not. any computer guidance system can be programmed). The cruisers could launch multiple waves of missiles that use slight amounts of burn to fan out around the cruiser and then hold off until a certain range to target. So if the cruiser has 24 missile bays firing 12 missiles per turn, there is no reason it couldn't assemble five turns of missiles in a spread around the cruiser waiting until 1,000,000 km from target to start accelerating to their targets. That's 1,440 missiles launched well outside of the 100D limit of the planet. The cruisers could have a jump plotted, decelerate to let the missiles get out of the way, and jump before they reach the planetary defenses. They never come into range, just the massive number of missiles they launched that are coming in at 500+ km/s. Nasty.

 

[GypsyComet]

??? I'm talking about incoming ships NOT being able to surprise and get the jump on a planet. Meson, PA, whatever. That ships are NOT coming out of jump and surprising a planet. The planetary defenses will have more than enough time to ready a ship disintegrating welcome. Given it is of comparable ability.

In other words, you can't pull off Taranto type op.

I wasn't talking about surprise. Meson vs PA is more of a reach issue. If a ship can loiter beyond the "shore" guns and still snipe at orbital installations, surprise is not needed. If the orbital elements include outnumbering naval units that come out and play the intruder can just jump out, having collected useful intel. If the intruder outnumbers they just stay beyond the reach of the equalizing shore batteries and pound the mobile defenders to scrap.

 

[sideranautae]

At 400 k/s you are about 1 hour from an Earth sized planet (starting from the 100 D area)... Plenty of time for the planetary based, Meson spinals to draw a real good bead

The same could be said of any forces approaching each other at any speed from a distance. Time to prepare.

Except, one is an entire planetary defense system. So, the incoming ships are going bye, bye. Missiles at speed can't be used against a planet either. They will burn up. ANY competent defense will include actual iron asteroids (not ships) way out in geosync that would chew up cruisers SO fast that you won't know it happened.

 

[GypsyComet]

ANY competent defense will include actual iron asteroids (not ships) way out in geosync that would chew up cruisers SO fast that you won't know it happened.

That assumes a siege mentality far bloodier than OTU material suggests. Not saying this is wrong, mind you, just completely undocumented.

Missiles at speed can't be used against a planet either. They will burn up.

If I'm planning a planetary bombardment, I'm not using normal missiles.