Inaccurate Jumps in Traveller

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phavoc
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Re: Inaccurate Jumps in Traveller

Postby phavoc » Fri Jan 19, 2018 9:32 pm

Jump failures would have multiple potential failure points. Just a few:

ship hits an unplanned jump shadow in the departure system
ship hits an unplanned jump shadow in deep space (rogue planet for example)
ship hits an unplanned jump shadow in a system it is passing through to get to its' destination
ship hits an unplanned jump shadow in the arrival system

That's just a start, but each one could potentially set up an adventure for the GM to implement. I particularly like the unplanned jump shadow in deep space because as the planet is traveling through the deep dark it's going to be totally unknown and unseen. Plus the chances of encountering it are going to be low since it has to line up pretty much exactly in order for a ships path to cross it. Without a sun it should be pretty cold, but if it's volcanic enough it might have some sort of narrow habitable zones, harsh they may be. But it can't be TOO volcanic, as it would most likely be picked up by infared astronomy.
NOLATrav
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Re: Inaccurate Jumps in Traveller

Postby NOLATrav » Sat Jan 20, 2018 12:27 am

phavoc wrote:
Fri Jan 19, 2018 9:32 pm
Jump failures would have multiple potential failure points. Just a few:

ship hits an unplanned jump shadow in the departure system
ship hits an unplanned jump shadow in deep space (rogue planet for example)
ship hits an unplanned jump shadow in a system it is passing through to get to its' destination
ship hits an unplanned jump shadow in the arrival system
These are good points and I like the rogue planet idea.

'Unplanned jump shadow' makes me think of T5, where a ship can be knocked out of jump if it is shadowed at any point during its entire time in jump. IIRC an example in the book is a patrol cruiser knocking another ship out of jump in the departure system a few days after it jumped, making it show up a week later in the same place it jumped out of. That to me is a bit harsh.

I guess that I think of the jump space dimensions as analogous to normal space since there is no time dilation or navigation, just a straight shot to the destination. So ships would know about shadows in the departure system and pretty much every system in between. But a rogue planet is a fun idea and I could see the rare use of an unexpected planetoid or ice ball in an intervening system pulling a ship out of jump. The question is time - if the rogue shadow is at the halfway point, would the jump last half as long as normal? Or the full week as in T5? In my linear way of thinking about jump the ship would precipitate in half the normal time... hmm, more to ponder...
baithammer
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Re: Inaccurate Jumps in Traveller

Postby baithammer » Sat Jan 20, 2018 5:54 am

It would still last a week + deviation as nothing a jump ship can do effects this. ( As noted in MGT, even jumping less than 1 parsec still uses the jump formulation.)
steve98052
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Re: Inaccurate Jumps in Traveller

Postby steve98052 » Sun Jan 21, 2018 11:15 pm

HalC wrote:
Fri Jan 19, 2018 1:09 pm
GURPS Traveller misjump rules aren't quite the same as Mongoose Traveller (HAH!), but for what it is worth:
. . .
The "take ten" rule seems more like a house rule, and if it isn't, I'd be happy to be pointed towards where it is listed. :)
Here's a reference, cited by Dr Kromm (line editor Sean Punch) himself:
http://forums.sjgames.com/showthread.php?t=1017
The next issue involved is the fact that piracy was considered to be mainstream enough that the original CT ship building rules included turrets and pirate encounters etc. NO real thought was given to what the rules themselves implied, nor did the rules do much more than make for a nice story telling vehicle without paying attention to implied issues.
This was an issue of all early role-playing games. They had role-play assumptions, but the rules often didn't reflect the world as described. Fantasy games had grossly overpowered and underpowered spells that seemed to have their power levels defined mostly by "rule of cool". Science fiction games ignored (or hand-waved) automation so that humans would be relevant, and had conflicting rules (such as the much-discussed difference between low passage and fast drug). The idea of a kinetic planet buster based on extended acceleration of a large mass was ignored because it wasn't fun, even if it's a clear result of reactionless maneuver drives. Traveller's economic models often didn't make sense; the first example of that most players discovered was the perpetual motion machine of a raw material producer world near a consumer world.

And of course space piracy is attractive by rule of cool, but the rules as published don't make much room for piracy to be economically viable.
. . .
GURPS TRAVELLER has a few other oddities involved where there are no "power plant fuel expenditures" on the basis that fusion plants use sufficient quantities of water to fuse into energy - that would last 200 years from a small amount. . . .
This is only an oddity compared with other editions of Traveller. I ran the figures, and a tank of liquid DT should not need refueling except during annual maintenance, when the tritium lost to radioactive decay would be replaced -- and if the tank includes a nuclear damper box (like the type used for californium artillery, as described in the classic Mercenary), the tritium could be made stable.
. . .
Ultimately? The company could ONLY make a profit if it sold refined fuel only, as the cost of transferring unrefined fuel was not cost efficient. . . .
The right way to do this may be with fuel tankers that are just fuel tankage and a power cell to keep the liquid hydrogen cold. Give them a shove with a tug near the skimming operation, let them coast for weeks or months, and catch them with tugs near the fuel retail operations.
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Re: Inaccurate Jumps in Traveller

Postby Reynard » Sun Jan 21, 2018 11:47 pm

"And of course space piracy is attractive by rule of cool, but the rules as published don't make much room for piracy to be economically viable."

Except on 21st century Earth. Someone seems to think it's viable enough to keep trying. Unlike Traveller players and referees, modern seagoing freight haulers never install weapons for protection or regularly insist on armed military or mercenary starship as escorts.
Sigtrygg
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Re: Inaccurate Jumps in Traveller

Postby Sigtrygg » Mon Jan 22, 2018 12:18 am

That depends where on the oceans you are sailing. Military escorts and patrols have been pretty standard off the coast of Somalia for a long time now, as has been the practice of hiring mercenaries to arm your merchant vessels.
Condottiere
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Re: Inaccurate Jumps in Traveller

Postby Condottiere » Mon Jan 22, 2018 1:18 am

http://www.dailymail.co.uk/news/article ... TODAY.html

Not always with a happy ending.

You could equip the ships with sonic and water cannons.
baithammer
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Re: Inaccurate Jumps in Traveller

Postby baithammer » Mon Jan 22, 2018 8:26 am

The problem is a lot of these protection outfits don't bother looking at local jurisdictions and think they can just transit through territorial waters with impunity.
phavoc
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Re: Inaccurate Jumps in Traveller

Postby phavoc » Mon Jan 22, 2018 2:31 pm

Traveller gaming ideas originated with a model of the age of sail - where piracy happened regularly against merchantmen on the high seas. And they would mount light armaments to deter pirates. Merchant ships never mount heavy armament since that takes away from your profitability.

There's also the little problem of the science behind jumps and the near impossibility it should be for any pirate to be able to intercept a merchantman jumping into, or out of a system. Now in-system merchants would be normal prey, but jump-capable ones would rarely be able to be intercepted, let alone boarded.
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Re: Inaccurate Jumps in Traveller

Postby baithammer » Mon Jan 22, 2018 3:42 pm

Neglecting the part where pirates have agents in ports and sometimes even infiltrate or turn some crew members to get in on the action.
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Re: Inaccurate Jumps in Traveller

Postby Reynard » Mon Jan 22, 2018 5:48 pm

Jump exits especially for profit minded merchants are going to be as close to a planet's 100d mark and as close to the destination port as possible. Same for exiting the system as you want to shave every minute you can and every kg of maneuver fuel. That narrows down where the vast majority of ships will be travelling. Ships also produce a jump flash everyone can detect. Pirates just have to 'fly casually' in that particular region and go fishing when an opportunity presents itself.
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Re: Inaccurate Jumps in Traveller

Postby steve98052 » Mon Jan 22, 2018 5:54 pm

Due to the mechanics of jump, piracy is implausible, except through rule of cool. Hijacking, however, is plausible.
Condottiere
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Re: Inaccurate Jumps in Traveller

Postby Condottiere » Mon Jan 22, 2018 7:58 pm

Dodgy jump cartridge, that has a preplaced worm, and arranges to exit the wormhole at the pre appointed place.
phavoc
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Re: Inaccurate Jumps in Traveller

Postby phavoc » Mon Jan 22, 2018 8:24 pm

Jump exits are at a 100D sphere, therefore the number of exits are, umm, large to say the least.

Even flying casually you never know when a ship is due to arrive. For the inside job to work, the departure system would have to hAve agents spying on the ships and trying to cypher out when a ship is departing, then jump out ahead wirh enough time to arrive without fail prior to the arrival time of the other ship. AND the pirates would then have to get into position and fly casually, maybe for days, before the other ship arrived. And that assumes they guess right on the exit position.

There are so many variables here that it would be highly unlikely to ever be in the right place, at the right speed and right vector to intercept a ship that can carry it's outbound speed through jump.
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Re: Inaccurate Jumps in Traveller

Postby NOLATrav » Mon Jan 22, 2018 9:39 pm

T5 posits that jump is a straight line from system to system, thus you could conceivably limit your casual flying/lurking to one hex face or about 15% of the 100D sphere. Still big but greatly reduced area.
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Re: Inaccurate Jumps in Traveller

Postby Reynard » Mon Jan 22, 2018 9:39 pm

"Jump exits are at a 100D sphere, therefore the number of exits are, umm, large to say the least. "

Unless a certain planet has high and low starports all over the globe, ships are not going to purposely exit J space far from the designated docking facility. The inherent window of jump time is considered part of a jump and calculated in a world's flight space. Ships are expected to arrive in authorized regions for safety, security and traffic control. A lot of space around a world will be for local and interplanetary traffic. You really don't need the headache of ships popping in as they please with shuttles, pinnaces and planetary megafreighters everywhere. The larger and busier the port the more ships need to meet flight constraints. This is why the chance of encounters grow as you focus on the point of destination.

"If ships travelled through the whole of the space in a system,
they would never encounter each other. However, spacecraft
tend to crowd to just a few places in any given system, such
as the hundred diameter jump limit of colonised worlds,
industrial belts in orbit, and gas giants and settled moons."

This is why the rules give even pirates a measly chance to be in the right place at the right time. One thing we seem to forget is there are regular routes ships ply within a system having nothing to do with Jump. Ships don't just meander in a system for no reason, they have destinations from planets to free-space stations and these are known. Anyone with the need can know the regular flight lanes between any of these points. Once again, ships are not going to waste fuel zigging and zagging to their target. Those pathways are what pirates and privateers find most tempting because of the variety of craft traveling in deep space. Remember that the old Corsair had a 100 ton bay that opened wide. Perfect for scooping anything from gigs to shuttles.
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Re: Inaccurate Jumps in Traveller

Postby phavoc » Mon Jan 22, 2018 10:44 pm

NOLATrav wrote:
Mon Jan 22, 2018 9:39 pm
T5 posits that jump is a straight line from system to system, thus you could conceivably limit your casual flying/lurking to one hex face or about 15% of the 100D sphere. Still big but greatly reduced area.
Right, however depending on the angles between systems, you could have a very large area, or relatively small area. Plus you could easily spend a little more time in the departure system to adjust where you wanted to arrive (i.e. above or below the plane of the eliptic, or even in 'front' of the orbital path of the planet you are jumping towards.

And don't forget, if you spend 2hrs boosting, even at 1G, a ship with 6G at rest doesn't have a chance of catching an arrival on the periphery.
Reynard wrote:
Mon Jan 22, 2018 9:39 pm
"Jump exits are at a 100D sphere, therefore the number of exits are, umm, large to say the least. "

Unless a certain planet has high and low starports all over the globe, ships are not going to purposely exit J space far from the designated docking facility. The inherent window of jump time is considered part of a jump and calculated in a world's flight space. Ships are expected to arrive in authorized regions for safety, security and traffic control. A lot of space around a world will be for local and interplanetary traffic. You really don't need the headache of ships popping in as they please with shuttles, pinnaces and planetary megafreighters everywhere. The larger and busier the port the more ships need to meet flight constraints. This is why the chance of encounters grow as you focus on the point of destination.
At 100D, pretty much all starports on a planet are going to be equidistant (within reason). From orbit, with a 1G drive, there isn't any destination on a planet that is more than 10-20min difference in arrival times.

To get some organization and safety out of all this, it is well within the realm of reason that a planet designate certain sectors to be arrival zones for ships from planets within jump range. And designate departure areas as well. That would hold true for busy systems, but systems that didn't get much jump traffic would not spend the effort to police these. And I agree that once ships pass the 100D limit they are going to be vectored in by traffic control at specific speeds.
Reynard wrote:
Mon Jan 22, 2018 9:39 pm
"If ships travelled through the whole of the space in a system, they would never encounter each other. However, spacecraft tend to crowd to just a few places in any given system, such as the hundred diameter jump limit of colonised worlds, industrial belts in orbit, and gas giants and settled moons."

This is why the rules give even pirates a measly chance to be in the right place at the right time. One thing we seem to forget is there are regular routes ships ply within a system having nothing to do with Jump. Ships don't just meander in a system for no reason, they have destinations from planets to free-space stations and these are known. Anyone with the need can know the regular flight lanes between any of these points. Once again, ships are not going to waste fuel zigging and zagging to their target. Those pathways are what pirates and privateers find most tempting because of the variety of craft traveling in deep space. Remember that the old Corsair had a 100 ton bay that opened wide. Perfect for scooping anything from gigs to shuttles.
There won't be any fixed paths in a system. Planets are in constant motion, so those shipping 'lanes' will be constantly shifting every week - at least from the inner planets to the outer ones. Take, for example, the path between Earth and Mars. It would be constantly shifting as the planets rotate on different speeds. Say your destination is on the same side of the star as your origin planet. Easy navigation. If it's on the other side, would you go over, under or around (left or right?) of the star? Orbital mechanics would generally tell you what is the safest path, but they would all essentially be equidistant.

Pirates would have far better chances of intercepting in-system traffic because there are predictable paths. Not so much with jump ships. And with no knowledge of when a ship will emerge from jump space, how does a pirate hide in plain sight? Outbound traffic will detect any ship flying in circles and report that back to traffic control - assuming that traffic control hasn't already spotted the ship. I suspect that busy planets will have cheap traffic sats seeded at the 100D limit to scan for traffic, and also have in-system ships transmitting scans to traffic control.
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Re: Inaccurate Jumps in Traveller

Postby baithammer » Tue Jan 23, 2018 12:08 am

Jumps have a time deviation of 6d6 hours which can leave you a fair ways away from your target, which means you'll need to transit to your destination.

Further, piracy wouldn't occur in well populated systems and with most trade vessels being jump 1 or 2 means that some trade routes require jumping through less populated / less regulated space.
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Re: Inaccurate Jumps in Traveller

Postby Reynard » Tue Jan 23, 2018 12:28 am

phavoc, I did not mean to suggest these are static, fixed flight ways but they are most definitely predictable by any space faring culture and easily plotted otherwise the target ships couldn't fly there. This is another task for astrogators beyond calculating jump travel. Spend some time investigating the system by exploration or a little legwork dock side and you'll have a picture of all destinations, their importance and what traffic is like. Just decide where would be the best choice for hunting.

"And with no knowledge of when a ship will emerge from jump space, how does a pirate hide in plain sight? "

Space is big, sensors aren't. If a ship can see another ship, so you can be seen. Most civilian ships have lousy sensors while pirates and privateers will try to improve. Only paranoid player characters automatically assume every ship is a pirate and attack. The more important and larger the planet for trade the more ships transiting and that means greater occurrence of possible targets. Ships will be concentrated in a traffic control pattern so you don't have to cover huge amounts of space. Also allows patrols to be actually useful. Ships enter and leave jump space creating a jump flash that can be detected at the distances of light speed. You are not looking for a specific ship (usually) but any ship within your sensor range and a jump flash can be a reason to investigate. Choose a target with the best chance for possible interception.

I rebuilt the Corsair class with EAG and Stealth so it has a good chance to stalk targets and not be spotted by patrols plus has High Burn Thrusters for the pounce. Those features make it easier to sit within interplanetary space lanes for days hoping for prey. As the Encounter rules show, it's not always successful and they either go resupply and try again or hunt elsewhere. Since many merchants also don't mount weapons, pirates with a merchant vessel and pop-up turrets have a great element of surprise before showing their colors.
Last edited by Reynard on Tue Jan 23, 2018 1:07 am, edited 1 time in total.
Linwood
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Re: Inaccurate Jumps in Traveller

Postby Linwood » Tue Jan 23, 2018 12:57 am

I think a pirate’s best chance for an interception (short of having a collaborator on board) is simply knowing their prey. For example, a subsidized merchant with a regular route may well target the same volume for entry on the 100D limit (probably whatever gives the ship minimum transit time to the star port). A knowledgeable pirate could try to take advantage of that pattern. Combine that with some deception - a fake distress call, transponder codes spoofing the local LEO vessels) and they might have a decent shot.

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