Jumpship RetroTech

[FedComGirl]

They could have purchased or stolen scrapped warships and fixed them up.

[wundergoat]

Or the could have been Periphery naval vessels that were never accounted for..or wrecks of the same.

What it comes down to is the old primitive jump drives were essentially lower tech compact cores.  As tech got better, the cores got smaller and the range got better.  Someone figured out how to make a core that was less mass efficient but worlds cheaper, and suddenly that became the best option for the merchant marine while the compact core remained necessary for warships.  There isn't anything that suggests using a primitive compact core would realize any cost savings.  Yes, it should be simpler but a lot of the improvement might just be refinement in the manufacturing methods, drive tuning, and just a better understanding of KF technology in general.

[Knightmare]

In term of cost, also keep in mind some of the strategic costs of widespread use of primitive drives.

At the time many of the primitive ships were using their engines to recharge. That equals more fuel, which equals more money. With the reduction in jump range you now require more fuel for more jumps to travel between Point A and Point B. And don't forget the refueling stations, repair facilities (since more jumps & travel to X planet = additional wear and tear on the shiny bits!) etc. The whole support infrastructure for Primitive drives is pretty hefty compared to the-now Standard Core.

While the difference of wear and tear between JumpShip Cores and Types might be negligible, the primitive types do tend to cost more overall simply because they're jumping more and using more fuel. I'm not sure what the distribution of GravDecks was either. If many of the primitive types lacked GravDecks, the cost of operation continues to increase.

Sure primitives might work as an attack vessel in a pinch, but wouldn't a Merchant loaded with a couple of modified Q-Ships work even better? I mean, if some pirate is going to go through the trouble of outfitting a decrepit Aquilla, why not just outfit a couple of Mules? By the Star League era, I'm sure a common Trade DropShip cruising through a system is going to raise a lot less eyebrows than an ancient Aquilla. They're both easier to hide in plain sight and make a get away - especially with a standard core. With an Aquilla I can now limit my search radius to systems in 15 rather than 30 light years.

Yea, space is big, but shouldn't recharging via the engines make it easier to locate in-system compared to a low, slow sun charge? Anyone know if that's true or been addressed? 
 

[Moonsword]

What it comes down to is the old primitive jump drives were essentially lower tech compact cores.  As tech got better, the cores got smaller and the range got better.  Someone figured out how to make a core that was less mass efficient but worlds cheaper, and suddenly that became the best option for the merchant marine while the compact core remained necessary for warships.  There isn't anything that suggests using a primitive compact core would realize any cost savings.  Yes, it should be simpler but a lot of the improvement might just be refinement in the manufacturing methods, drive tuning, and just a better understanding of KF technology in general.

How much smaller they got is an open question.  A modern WarShip built to the same specifications as an Aquilla on everything but armor has right around 5.1k tons of extra space.  Keep in mind that one of the tonnage numbers we don't have is the transit drive.  Since we know primitive fighter drives are somewhat larger, it stands to reason that part of that may be going into the power plant and transit drive, not the core.  Interestingly, their fuel efficiency isn't any worse - the Aquilla uses the same 19.75 tons per burn-day as a modern unit would.  Fighter cockpits are also larger, so again, there's another possible place some of that tonnage is lurking, although that's a much smaller piece of it unless the primitive controls were designed for elephants instead of people.

Answering all of this is going to require Interstellar Operations to do more than reverse-engineer the total "missing" tonnage the way I did.

Yea, space is big, but shouldn't recharging via the engines make it easier to locate in-system compared to a low, slow sun charge? Anyone know if that's true or been addressed? 

It hasn't been addressed, per se, but it's not that big an issue.  Thermal and optical detection ranges (which this falls under) are low enough that most of the time radar detection is much more likely to pick the target up before you need to worry about that.  The "engine" isn't running, just the fusion plant, and therefore there's no drive plume to detect from 10 light-seconds out.  Check out the sensor rules on StratOps pages 117-119; the relevant sections are on page 119.

[Paladin1]

Actually this brings up a good point.  Would a Neutrino detector work better or worse on this primitive type of drive?

[Knightmare]

Actually this brings up a good point.  Would a Neutrino detector work better or worse on this primitive type of drive?

That's what I was thinking.

It hasn't been addressed, per se, but it's not that big an issue.  Thermal and optical detection ranges (which this falls under) are low enough that most of the time radar detection is much more likely to pick the target up before you need to worry about that.  The "engine" isn't running, just the fusion plant, and therefore there's no drive plume to detect from 10 light-seconds out.  Check out the sensor rules on StratOps pages 117-119; the relevant sections are on page 119.

Thanks Moon - I was trying to remember the relevant section. Appreciated!

[Moonsword]

Actually this brings up a good point.  Would a Neutrino detector work better or worse on this primitive type of drive?

You might want to review Cray's post here on them.  Since neutrino detectors are one of those things stuffed in a deep, dark hole out in the wilderness along with Far Country, I'm not sure this is something to worry about most of the time.

That said, neutrino detectors are looking for the fusion plant.  What matters is the fact that the fusion reactor is running.  Whether or not the difference in intensity and time (less and more, respectively) for a primitive core is important, I don't know, but the fact that they can reportedly spot the fusion plant of a Star League family car from 10 AUs argues that the reactor rate is irrelevant at the scale we're talking about, so you're probably exposed anyway.  On the other hand, unless you were sitting at the emergence point (which is a great way to get found by other sensors if someone bothers to go out there and look), the fusion plant was probably turned on to maneuver at some point, so the detector may have a very good chance of finding you whether you're charging from a sail or not.

[FedComGirl]

Sure primitives might work as an attack vessel in a pinch, but wouldn't a Merchant loaded with a couple of modified Q-Ships work even better? I mean, if some pirate is going to go through the trouble of outfitting a decrepit Aquilla, why not just outfit a couple of Mules? By the Star League era, I'm sure a common Trade DropShip cruising through a system is going to raise a lot less eyebrows than an ancient Aquilla. They're both easier to hide in plain sight and make a get away - especially with a standard core. With an Aquilla I can now limit my search radius to systems in 15 rather than 30 light years.

Mules can't jump away with their plunder or to get away from in coming warships. Besides by modern times I think if anyone saw a jumpship underway they'd think it was a warship. The results being they'd be fired on. Aquilla operators, if there are any, probably just used them as regular jumpships with no docking collars.

[Knightmare]

Mules can't jump away with their plunder or to get away from in coming warships. Besides by modern times I think if anyone saw a jumpship underway they'd think it was a warship. The results being they'd be fired on. Aquilla operators, if there are any, probably just used them as regular jumpships with no docking collars.

I'm just wondering why a Mule would have to get away from incoming WarShips. By the Star League era, using the DropShip/JumpShip combo could conceivably allow a Pirate group to hide in plain sight among normal civy traffic. If said group saw a WarShip protected convoy - Pass. Just hang out long enough for something better or move on to greener pastures. An ancient Aquilla might immediately draw unwanted attention. Sure you could eventually jump out, (Can primitives mount a L-F Battery?) but not before you're tagged.

Think of it like this. How often do you notice a specific run of the mill Honda or Volvo in the swarms of automobiles driving on the road? What about a Model-T or other super old Antique? Once a design becomes so antiquated outside of the norm the design's liabilities start to outweigh its usefulness depending on future use and user. In this case - Pirates.
 

[Moonsword]

I'm just wondering why a Mule would have to get away from incoming WarShips. By the Star League era, using the DropShip/JumpShip combo could conceivably allow a Pirate group to hide in plain sight among normal civy traffic. If said group saw a WarShip protected convoy - Pass. Just hang out long enough for something better or move on to greener pastures. An ancient Aquilla might immediately draw unwanted attention. Sure you could eventually jump out, (Can primitives mount a L-F Battery?) but not before you're tagged.

An excellent point about hiding.

We don't know whether they can in a rules sense (this is another one of those questions that's presumably going to be answered in Interstellar Operations), but the question of would primitive cores mount a lithium-fusion battery has a very simple answer: very, very unlikely.  They weren't formally introduced until 2531 (possibly on the Avatar cruisers, depending on whether the stats we have are for the first build or not), and even giving it a century of leeway for one-off prototypes (something I'm not inclined to do in my games, mind you, but I'll go along with it for the sake of argument here) would still be in the mid-2400s, over a century after the modern compact core was introduced.  They'd have to deliberately break out much older designs and tools to do the work with rather than designing around conventional, contemporary techniques.  Retrofitting with lithium-fusion batteries is evidently expensive and time-consuming, so I don't really see someone with the technology (which, in this time period, is the Hegemony and maybe the other Houses) as likely to expend the effort on primitive core designs.

[DarthRads]

An excellent point about hiding.

We don't know whether they can in a rules sense (this is another one of those questions that's presumably going to be answered in Interstellar Operations), but the question of would primitive cores mount a lithium-fusion battery has a very simple answer: very, very unlikely.  They weren't formally introduced until 2531 (possibly on the Avatar cruisers, depending on whether the stats we have are for the first build or not), and even giving it a century of leeway for one-off prototypes (something I'm not inclined to do in my games, mind you, but I'll go along with it for the sake of argument here) would still be in the mid-2400s, over a century after the modern compact core was introduced.  They'd have to deliberately break out much older designs and tools to do the work with rather than designing around conventional, contemporary techniques.  Retrofitting with lithium-fusion batteries is evidently expensive and time-consuming, so I don't really see someone with the technology (which, in this time period, is the Hegemony and maybe the other Houses) as likely to expend the effort on primitive core designs.

Yeah, teh Avatar is the earliest design we have so far for LF Batterie

[FedComGirl]

I'm just wondering why a Mule would have to get away from incoming WarShips. By the Star League era, using the DropShip/JumpShip combo could conceivably allow a Pirate group to hide in plain sight among normal civy traffic. If said group saw a WarShip protected convoy - Pass. Just hang out long enough for something better or move on to greener pastures. An ancient Aquilla might immediately draw unwanted attention. Sure you could eventually jump out, (Can primitives mount a L-F Battery?) but not before you're tagged.

Because unless they can jam the jumpships communications, the jumpship is going to call for help. That means the pirates would have to have a jumpship and dropship to evade capture. Which of course many do. An Aquila though can bluff others as being a warship as it can move about, which jumpships can't do. Then it can plunder and jump away. Or it could pretend to be a regular jumpship without docking collars if it jumps into occupied territory.

Think of it like this. How often do you notice a specific run of the mill Honda or Volvo in the swarms of automobiles driving on the road? What about a Model-T or other super old Antique? Once a design becomes so antiquated outside of the norm the design's liabilities start to outweigh its usefulness depending on future use and user. In this case - Pirates.

That all depends. I tend to notice older cars because I drive them older cars. I also love classics so they stand out to me. Newer cars though, I have a hard time telling apart.



The Periphery or anyone who wanted to be able to evade attack might be interested in a battery.

[Daryk]

More precisely, jumpships can't "move about" at 1G acceleration.   A "station keeping" drive's tenth of a G is plenty to move around a solar system on anything above a tactical time scale.

[FedComGirl]

Good point.  They're still targets though.

[Knightmare]

That all depends. I tend to notice older cars because I drive them older cars. I also love classics so they stand out to me. Newer cars though, I have a hard time telling apart.

Guess that's one of the benefits of using the standard DropShip/JumpShip routine when raiding. There's also some benefit to using DropShips over Small Craft when pillaging transferring cargo from one vessel to another. A standard JumpShip/DropShip duo has the option. The Aquilla, not so much. Assuming of course, the target craft has an extra docking collar you can connect directly with the target JumpShip. Alternatively, a Pirate group with extra docking collars can simply steal a target DropShip in its entirety. Armed with an Aquilla, again, not so much. Honestly though, either setup can still steal a JumpShip, so that's a moot point and fun!   

[FedComGirl]

Guess that's one of the benefits of using the standard DropShip/JumpShip routine when raiding. There's also some benefit to using DropShips over Small Craft when pillaging transferring cargo from one vessel to another. A standard JumpShip/DropShip duo has the option. The Aquilla, not so much. Assuming of course, the target craft has an extra docking collar you can connect directly with the target JumpShip. Alternatively, a Pirate group with extra docking collars can simply steal a target DropShip in its entirety. Armed with an Aquilla, again, not so much. Honestly though, either setup can still steal a JumpShip, so that's a moot point and fun! 

The Dropship/Jumpship combination is a big advantage why why the older jumpships faded away but there's still some small ones that can't carry dropships. Actually not having docking collars could be a plus because pirate dropships couldn't match up with them. They'd have to send small craft. Being able to maneuver then is a big advantage. It really all depends on the skipper and crew though. Some don't like fun. :)

[Knightmare]

The Dropship/Jumpship combination is a big advantage why why the older jumpships faded away but there's still some small ones that can't carry dropships. Actually not having docking collars could be a plus because pirate dropships couldn't match up with them. They'd have to send small craft. Being able to maneuver then is a big advantage. It really all depends on the skipper and crew though. Some don't like fun. :)

Too true. (But I have to say, no pirate crew in their right mind would ride a Jumper without rings! Otherwise, they'd just go with the Aquilla! ;))

[Moonsword]

The Dropship/Jumpship combination is a big advantage why why the older jumpships faded away but there's still some small ones that can't carry dropships. Actually not having docking collars could be a plus because pirate dropships couldn't match up with them. They'd have to send small craft. Being able to maneuver then is a big advantage. It really all depends on the skipper and crew though. Some don't like fun. :)

It could be but they're not especially common, with only two known classes, and those are both late in the game for what we're talking about and at the opposite ends of the scale for target desirability.  As a result, it's difficult to talk about what any of this looks like in general.  If you want to look the classes up, they're both in the back of TRO3026R and the Explorer was also republished in TRO3075.

One of those two classes is the Explorer, which will actually get targeted aggressively because they were frequently used as VIP transports.  That's a known pattern for piracy and other forms of accomplishing a kidnapping because it historically can pay off pretty nicely.  Given that they were unarmed, they probably stayed to well-policed travel routes where piracy was rare.  The other is the Quetzalcoatl, which is a former Scout (and therefore not necessarily deliberately targeted depending on how visible that is) that traded the collar for a pair of fighter squadrons and doesn't really have a lot of cargo space, nor any integral ability to move transportation for it, so it's primarily going to be supporting fighters out of the capacity.  This is for obvious reasons not really a desirable target under most circumstances unless you're just that hard up for spare parts and gas.

[rlbell]

In term of cost, also keep in mind some of the strategic costs of widespread use of primitive drives.

At the time many of the primitive ships were using their engines to recharge. That equals more fuel, which equals more money.

Yea, space is big, but shouldn't recharging via the engines make it easier to locate in-system compared to a low, slow sun charge? Anyone know if that's true or been addressed? 
 

Ignoring FASAnomics, charging with solar power represents a false economy.  Replacing the sail with the equivalent mass of extra tankage should be enough hydrogen fuel for the main powerplant to jump once a week for many decades, if not centuries.  The starlight is free, but the energy collector costs money.  Unless the fusion plant is shut down while charging the jumpcore, the power output of a fusion engine running at a low enough power to keep the plasma warm and running at a low enough power to keep the plasma warm while charging the core.

You might want to review Cray's post here on them.  Since neutrino detectors are one of those things stuffed in a deep, dark hole out in the wilderness along with Far Country, I'm not sure this is something to worry about most of the time.

That said, neutrino detectors are looking for the fusion plant.  What matters is the fact that the fusion reactor is running.  Whether or not the difference in intensity and time (less and more, respectively) for a primitive core is important, I don't know, but the fact that they can reportedly spot the fusion plant of a Star League family car from 10 AUs argues that the reactor rate is irrelevant at the scale we're talking about, so you're probably exposed anyway.  On the other hand, unless you were sitting at the emergence point (which is a great way to get found by other sensors if someone bothers to go out there and look), the fusion plant was probably turned on to maneuver at some point, so the detector may have a very good chance of finding you whether you're charging from a sail or not.

Neutrino detectors in the BTU are an even bigger departure from the laws of physics than BT fusion engines, or are subject to huge amounts of hyperbole.  Neutrino detectors work by the tyranny of numbers.  To detect a neutrino, you present a large amount of matter for it to interact with and hope that, despite the long odds, enough neutrinos interact with the detector make an observation.  Current detectors are not sensitive enough to provide realtime data on the Sun's location, even though they only have a fifty percent chance of missing a single photon created by a neutrino interaction (for every pair of neutrinos that they could detect, they only miss one), as, despite all of the neutrinos put out by the sun a second, less than one neutrino per hour interacts with the detector.  The other difficult part in a neutrino detector is that there are many, many other particles out there, so the detector has to be shielded from everything else.  Current detectors are in disused mineshafts one or two miles below the surface, but they are drilling a new one into the Antarctic icesheet.  As the ice is already there and transparent at the photon energies of interest, they can make the detector hundreds meters across, instead of merely tens.

Even these 'primitive' neutrino detectors will register a neutrino from a fusion powered car at 10 AU.  You just need to be patient and not have any other sources to mask the faint signal with noise, such as a star at one AU, or a running fusion plant only a few tens of meters away.

[Moonsword]

Ignoring FASAnomics, charging with solar power represents a false economy.  Replacing the sail with the equivalent mass of extra tankage should be enough hydrogen fuel for the main powerplant to jump once a week for many decades, if not centuries.  The starlight is free, but the energy collector costs money.  Unless the fusion plant is shut down while charging the jumpcore, the power output of a fusion engine running at a low enough power to keep the plasma warm and running at a low enough power to keep the plasma warm while charging the core.

No, it won't, because FASA physics is in play.  It takes approximately 10 burn-days to charge a jump.  Again taking the Merchant as an example, this is nearly 200 tons of fuel.  The sail, meanwhile, is only 46 tons.  There's no false economy here - the sails are a more efficient and cost effective solution.

Even these 'primitive' neutrino detectors will register a neutrino from a fusion powered car at 10 AU.  You just need to be patient and not have any other sources to mask the faint signal with noise, such as a star at one AU, or a running fusion plant only a few tens of meters away.

I was talking about precisely the ones Cray was in that comment and didn't bother to narrow it down.  You're quite right on how real world systems operate.  We're not dealing with those.

Knowing there's some extra neutrinos (assuming they can filter an extra plant out from noise from every other source, like say that local star you mentioned) isn't necessarily that big a deal.  That's not what BT neutrino detectors do.  Go back to that discussion I linked to.  There are some of them mounted in shipboard installations, which is not a great condition for noise isolation with that honking big fusion plant a few hundred meters back and a density of hull materials that puts Weberfoam to shame, and then there's the ones people are walking around with in their hands.  They will automatically see all of the fusion plants in 10 AUs, never mind whether the star is there or not, and at ranges that no other sensor aside from emergence wakes can manage.  (Yes, BT sensor ranges are short.  Welcome again to the difference between physics texts and the rule books.)  They'll also apparently find the locations, which is a major headache for someone trying to hide.

It's the technomagical ones that are dumped in the hole here.

[rlbell]

No, it won't, because FASA physics is in play.  It takes approximately 10 burn-days to charge a jump.  Again taking the Merchant as an example, this is nearly 200 tons of fuel.  The sail, meanwhile, is only 46 tons.  There's no false economy here - the sails are a more efficient and cost effective solution.

Two hundred tons of hydrogen is good for up to 54x10^18 joules.  A ten square kilometer jumpsail (bigger than any described in the canon) at 10 AU from the Sun can collect  1x10^15 joules in the week taken to charge the core.

[Moonsword]

Two hundred tons of hydrogen is good for up to 54x10^18 joules.  A ten square kilometer jumpsail (bigger than any described in the canon) at 10 AU from the Sun can collect  1x10^15 joules in the week taken to charge the core.

You missed the point of what I was saying.  Let's try this again.  I'll repost that remark so that we don't have to look at it again.

No, it won't, because FASA physics is in play.  It takes approximately 10 burn-days to charge a jump.  Again taking the Merchant as an example, this is nearly 200 tons of fuel.  The sail, meanwhile, is only 46 tons.  There's no false economy here - the sails are a more efficient and cost effective solution.

To expand on that, I'm not aware of a problem with your math and I'm not challenging the actual science here.  The problem is with your starting assumption that the formulas you're using accurately describe Reality According To FASA.  They don't.  This is why I said that this time around the problem isn't the fact that BattleTech economics are apparently made to make sense to Cthulhu, it's the fact that this is one of those times and places FASA's physics simply doesn't line up with reality.  In this one case there's compelling economic logic to this decision.

If you open StratOps and turn to page 88, you'll see the following: "Each power plant-based charging attempt of the drive requires 10 burn-days of fuel[,]" which is modified by margins of success or failure on a control roll on that same page.  It may go as low as 4 burn-days or if you truly screw up, it can go a lot higher, but 10 burn-days is a good quick and dirty reference.  Taking the Merchant as an example, we have a 120k ton hull according to TRO3057R page 92.  The sail is 46 tons (30 + 120k/7.5k) per formula on StratOps page 149.  The tons per burn-day figure is 19.75 for a hull this size (StratOps page 147), thus we have 197.5 tons, which I rounded up to 200 tons last time.  Fuel costs 15k C-Bills per ton according to StratOps page 179, although if you have a whole bunch of units sitting around doing nothing during a maintenance cycle but cracking water, you can supply it for free but then you've got to ship it out, which requires more gas, and thus more fission, fusion, or solar engines to do the cracking, and thus more deferred maintenance.  From the JumpShip owner/operator's point of view, that's probably academic.  I will note that in this area there may be FASAnomics involved since that figure may be either cheaper or more expensive than it needs to be.  Those of you who are interested may want to calculate the cost of sufficient .25 ton TR D fusion plants using the support vehicle rules to make hydrogen from water, their maintenance costs, and the incidental cost of shipping it out.

That standard 10 burn-days I mentioned costs 2.9625 million C-Bills. Anyway, fuel use may be somewhat lower but at best you can never expend less than 79 tons of fuel (1.185 million C-Bills) on this operation, and even being generous and saying they routinely manage a margin of success of 8 on the aforementioned control roll, you're expending at least 158 tons (2.37 million C-Bills) charging the core.  This is without any questions about station-keeping.  You've got to replace that about once a week and given where JumpShips usually jump in, doing it involves burning a lot of gas in and of itself.  The cost of the sail, including the final cost modifier, is 2.875 million C-Bills.  If you don't do better, it's cheaper in one week to just pay the money out for the sail.  It'll pay for itself on two jumps with an MOS of 8 on each one and in three jumps with the absolute minimum figure.  In this particular case, the cost of just paying the sail is lower.  They're using it because the physics is screwed up and, over time, it's cheaper than buying and shipping hydrogen

Whether the energy efficiency here has anything to do with the energy efficiency of this same hydrogen when used for thrust is another interesting question I'll leave for someone else.