How do jump drives really work?

[hdan]

I already covered that in my earlier post.

Forgive my dimness, but I couldn't find an earlier post in this thread from you that wasn't about light speed. Well, there was one that mentioned LHyd being a conductor, but that was a brief riposte to another statement.

Not trying to be difficult; just interested in reading your post and not very familiar with CoTI searching facilities.

/hdan

 

[whartung]

Greetings !

You should get a copy of Digest Group Publication's Starship Operator's Manual. The book provides some well very thought-out descriptions of how key starship systems function, including the Jump drive.
The book is slanted toward civilian ships, as the ship given as an example is the Far Trader. There is some basic information regarding military ship systems.

Do you think you can summarize what it says and how it relates to the discussions here? Not everyone has access to that 23 year old book.

 

[mike wightman]

The amount of energy they store and the time frames involved are completely dissimilar.

That's sort of the whole point - AN accumulators take weeks hence the Imperium adopting the hydrogen based jump drive as standard.

Won't work, because the technology involved is incompatible with that of the OTU.

No it isn't.

Irrelevant.

The guy who wrote it all is irrelevant?

That's the reason why the Annic Nova is incompatible with the universe that has evolved over the 30 years that has gone by since JTAS#1 was published. And that's why articles from JTAS #1 are inferior canon.

So now we have levels of canon?

So much of the OTU is inconsistent for the very reason that the designers just wanted a pinboard to stick stuff to.

Marc wrote Annic Nova as an OTU adventure, set in the golden age of the 3rd Imperium - accept it and explain.

What's the maximum amount of energy that can be collected by the Annic Nova's solar sails in six weeks, let alone one? If we accept the Annic Nova as a viable design, it follows that the amount of energy you actually need to initiate a jump is equal to or less than this amount. How much of a power plant would you need to equal that? I suspect you would be able to equal it with a small steam engine, but I may be wrong there. Be that as it may, you most certainly don't need 170T worth of machinery to do so. There must be far smaller alternatives. Just because the Annic Nova is a very impractical design doesn't mean more practical ones aren't possible -- if the implications are true.

Please don't try and bring real world physics into this - for all it's vector movement system (which is wrong) - Traveller is very much handwavium.

I still don't see what relevance that has.

Marc wrote it.

Without asking him I would guess it was to show how the rules could be used to provide alternatives - don't like huge hydrogen tanks have a solar collector instead - works the same if not a little bit worse.

 

[mike wightman]

Greetings !

You should get a copy of Digest Group Publication's Starship Operator's Manual. The book provides some well very thought-out descriptions of how key starship systems function, including the Jump drive.
The book is slanted toward civilian ships, as the ship given as an example is the Far Trader. There is some basic information regarding military ship systems.

That is all.
H. Leidner

While a very fine book I have reason to believe that the folks at DGP didn't have the latest version of CT to base their rules on - hence MT is broken with regards to CT.

 

[E.D.Quibell]

Acording to MT:Referee's Manual[*], a 20 kiloliter (roughly 1½ dTon) power plant has an output of 25 Mw and a fuel consumption of 0.0125 kiloliter per hour. That would be enough to match the performance of that 100m2 solar collector.

[*] If I've managed to work out the sums correctly, which may not be the case.​

I really don't think it would be a good idea to establish this technology as viable for the OTU.


Hans

You missed the scale efficency.

Minimum size fusion power plant at TL9 (10 kl) produces 40 Mw.

At TL10, a 9 kl fusion power plant produces 9x2x1.5 or 27 Mw. For 25 Mw you need 8.34 kl of power plant. At 0.003 kl/h fuel per kl volume of power plant you need 0.02502 kl/h or 4.20336 kl fuel per week (25.22016 for six weeks).

All for MCr 1.668 (capex) and MCr 0.000883 (six week opex).

Best regards,

Ewan

 

[whartung]

Part of the problem is writers in the old days did not follow cannon.

The big problem is that the writers didn't have to engage in the back and forth, interactive discussions with a diverse population of enthusiasts to try to reconcile those decisions of theirs that were made in a coffee shop or the morning shower but are now considered "The Word", particularly on topics that were simply not fleshed out.

Seems to me that from the JTAS 24 article (which is a later article, by MWM, post HG, and actually pretty long), there's few key concepts from the JTAS article.

One is that Something Other than a Fusion Power Plant can provide energy for the jump. Solar power was mentioned in the article.

Two, that a combination fusion/jump drive system can produce "excess power" if it inefficiently consumes fuel. This excess power is enough to charge the caps and perform the jump, and this power can be generated is "just a few minutes".

Three, that the Jump caps can be charged "over time", there appears to be no real rush to charge the caps quickly, only that they can discharge quickly.

None of these are inconsistent with what I've seen if we accept the large fuel requirements as simply the "Standard Operating Procedure" and "Best Practice" of how J-Drives are used, rather than the ONLY procedure and ONLY practice.

The only one that's really stands out now is the "unrefined fuel" causing misjumps, which now seems quite odd since most references imply all of the fuel is used prior to jump.

I can see how, potentially, unrefined fuel can, maybe, ABORT a jump in process, especially if you're using the SOP "charge it all at once burning lots of fuel quickly" technique. I can see unrefined fuel "clogging the Power plant" or whatever, thus delaying the charging sequence. But once the caps are charged, seems a lot less to go wrong IMHO. Hell, "dirty" LHyd probably does a better job cooling than "clean" LHyd does.

 

[aramis]

Part of the problem is writers in the old days did not follow cannon.

The Annic Nove for one.
Calling a Kinunir a Battle Cruiser at 1200 tons
A lot of the FASA Adventure class ships had weapons bays while weighing in at under 1000 tons. I could almost see a 500 ton ship getting a 50 ton bay but they still included a full compliment of hard points.

Writers were throwing all sorts of odd things at us for years, many before High Guard and Trillion Cred Squadron.

Cannon is trying to make sense out of all these tidbits. Not much can be resolved without SOME conflict.

As a aside, Maybe Annic Novas collectors also act as a hydrogen scoop when the ship is going into jump. A ramjet so to speak. It would explain all the extra tonnage. The entire ship feels like a prototype Battletech Jump ship before the game took off. It was the first double adventure so the timing is about right.

The Kinunir and Leviathan adventures were written by GW not GDW, and apparently written before HG was finished. In a Bk2-sized universe, the Kinunir was a cruiser, and a heavy one at that...

before HG came out and hit your campaign, the TU was topped out by 5000 ton battleships... at J1...

 

[rancke]

That's sort of the whole point - AN accumulators take weeks hence the Imperium adopting the hydrogen based jump drive as standard.

I must say that I've never thought that the 1 to 6 week timeframe was due to the accumulators being unable to store power at more than a given rate; I've always assumed that it was due to the amount of energy the solar sails were able to collect. I was misled by the bit in the text about the recharge rate depending on the distance from and spectral type of the star serving as radiation source.

But that's not the problem. The problem is that if the information in the adventure is correct, then the amount of energy the Annic Nova's jump drives need to function can be estimated and is very low. The amount of energy required is so low that a very small conventional power plant can fill those accumulators in half a week (the 1 to 6 weeks is what it takes to recharge fully, which means enough energy to power each of the two jump drives once). Who needs solar sails? Just put a power plant aboard and you can recharge while in jump. You're in there for a week anyway, so why not fill those accumulators in the meantime?

No it isn't.

Yes it is. If the Annic Nova's drives and accumulators actually worked the way the adventure claims, there would be some radical alternate design possibilities. Since the design system doesn't have those options, they evidently don't exist. Because if they did exist, they would be listed.

The guy who wrote it all is irrelevant?

The fact that it was him rather than one of the other Grand Old Ones is irrelevant.

So much of the OTU is inconsistent for the very reason that the designers just wanted a pinboard to stick stuff to.

And if all you want to do is to stick your own stuff to your own pinboard, do so with my blessing (not that you need it). But if you want to argue about the present-day manifestation of the OTU, then it's the accumulated body of 30 years' worth of material that's pertinent -- not the reason why one small part of that body came about 30 years ago.

Marc wrote Annic Nova as an OTU adventure, set in the golden age of the 3rd Imperium - accept it and explain.

Marc Miller and everybody else who wrote official campaign material over the years created a huge body of material, of which the Annic Nova adventure is one tiny bit. I would gladly accept it if I could do so without messing up a much bigger part of canon. But I can't. So, no.

Please don't try and bring real world physics into this... - for all it's vector movement system (which is wrong) - Traveller is very much handwavium.

Please don't tell me what to bring into this. It's not about real world physics. It's about self-consistency.

Marc wrote it.

Without asking him I would guess it was to show how the rules could be used to provide alternatives - don't like huge hydrogen tanks have a solar collector instead - works the same if not a little bit worse.

Without asking him I would guess it was to dash off an adventure for JTAS #1. But it really doesn't matter why he did it, 30 years ago. What matter is how well it fits with the rest of canon now, 30 years later.


Hans

 

[E.D.Quibell]

The Kinunir and Leviathan adventures were written by GW not GDW, and apparently written before HG was finished. In a Bk2-sized universe, the Kinunir was a cruiser, and a heavy one at that...

before HG came out and hit your campaign, the TU was topped out by 5000 ton battleships... at J1...

Was it really? I never knew Kinunir was written by the guys at GW. Nothing in the book suggests this. Where did you find this out Will?

Best Regards,

Ewan

 

[mike wightman]

I am so glad whartung jogged my memory - from the definitive jump space articel by MWM (the same one that the guys at GT invented jump masking over )

Normally, only a fusion power plant can supply this energy. Some alternative systems make use of soar power generators (which operate much more slowly)

And that was written in 1985 - by which time the OTU was firmly established.

Oh, and I still think the GT lot got it wrong with jump masking

 

[mike wightman]

Was it really? I never knew Kinunir was written by the guys at GW. Nothing in the book suggests this. Where did you find this out Will?

Best Regards,

Ewan

It wasn't

It was written by GDW.

GW published it under license in the UK.

 

[rancke]

I am so glad whartung jogged my memory - from the definitive jump space articel by MWM (the same one that the guys at GT invented jump masking over )

Normally, only a fusion power plant can supply this energy. Some alternative systems make use of soar power generators (which operate much more slowly)

And that was written in 1985 - by which time the OTU was firmly established.

To quote something Marc Miller once wrote on the TML: "It also has to make sense".

Yes, anything Marc Miller says certainly has a LOT of weight. But even he can't actually change the laws of logic. If Marc Miller says two things that are mutually contradictory, one of them has to be wrong. It really is as simple as that.

Now, which one of them is wrong is, of course, Marc Miller's decision to make. Sadly, however, in a number of cases he hasn't made that decision. So we have to muddle along without it.

Oh, and I still think the GT lot got it wrong with jump masking

And yet, it was endorsed by Marc Miller himself.

Not that I'd care very much if jump masking was retconned away again. I do think that it has some interesting ramifications, but since no adventure so far has actually explored those ramifications, jump masking could be excised with no bad effects on the OTU.


Hans

 

[abomination]

I thought it was because of the space pixies

 

[Ishmael]

Acording to MT:Referee's Manual[*], a 20 kiloliter (roughly 1½ dTon) power plant has an output of 25 Mw and a fuel consumption of 0.0125 kiloliter per hour. That would be enough to match the performance of that 100m2 solar collector.

irrelevant
You asked this question

What's the maximum amount of energy that can be collected by the Annic Nova's solar sails in six weeks, let alone one? If we accept the Annic Nova as a viable design, it follows that the amount of energy you actually need to initiate a jump is equal to or less than this amount.

and I gave a very rough estimate. We don't know how many square meters the annic nova's solar collectors are, and we should be able to assume that their efficiency is significantly greater than 18%. Closer to the star gives more energy; farther gives less, with correspondingly shorter or longer j-cap charge times.
Therefore, we can gauge that the energy needed to initiate jump for a 600dton ship is less than or equal to, what...90 Gw? using a deliberately low estimate of the solar collectors energy capture rate. It could be 3, 5 or even 10 times this energy estimate due to larger collector size, better efficiency and/or greater incident radiation.
The fact that a fusion plant can charge the caps faster is probably the reason that solar collectors are not in widespread use. But that's not the same as 'they cannot exist'.

So how much energy does canon say is needed to initiate jump? Is it significantly different from this crude estimate? by orders of magnitude? Enough of a difference to say it cannot exist at all, even in all of known space?

 

[rancke]

So how much energy does canon say is needed to initiate jump? Is it significantly different from this crude estimate? by orders of magnitude? Enough of a difference to say it cannot exist at all, even in all of known space?

Seeing as 1½ T is one quarter of one percent of 600T and that the energy we're talking about is enough to support one jump by a jump-2 drive PLUS one jump by a jump-3 drive -- something that would require devoting 50% of those 600T to fuel tankage using the "conventional" method -- I'd say it was significantly different, and I'd say that without even bothering to do the calculations.


Hans

 

[Ishmael]

that avoided the question
What is the canon energy requirements for entering jump space?
in SI units, if you please....

if its unknown or unstated, just say so.

guesstimating based on fuel tankage that would be needed for regular jump doesn't count unless you can state either "All jump fuel is used to produce energy" or "X% of jump fuel is used to produce energy and the rest is used for 'blahblahblah'".

 

[whartung]

To quote something Marc Miller once wrote on the TML: "It also has to make sense".

Yes, anything Marc Miller says certainly has a LOT of weight. But even he can't actually change the laws of logic. If Marc Miller says two things that are mutually contradictory, one of them has to be wrong. It really is as simple as that.

Which two things in conflict are you referring to?

And yet, it was endorsed by Marc Miller himself.

Are you saying the MWM endorsed Jump Masking, or GT, in total, and in general. It would be hard to imagine MWM not endorsing GT as a whole.

"Yea, I gave them a license but it's all wrong and GT sucks. All of those books are garbage."

Somehow, I don't see that happening. Yet, simply endorsing GT does necessarily mean he endorses all of the mechanics portrayed therein. Arguably, the mechanics that MWM endorses specifically are in CT, MT, T4, and T5, since he (apparently) had much more of a hand in those rulesets.

I'm interested in Jump Mechanics because I think the detailed jump sequence can lead to potentially interesting situations. The "slow charge", "low fuel" jump is potentially interesting as a last ditch survival mechanic.

Perhaps Jump Caps are "leaky" and a normal power plant can't charge them fast enough to overcome the leakage, but in "burn, baby, burn" mode, it can overcome the leakiness of the caps enough to fill them, and then you have a window between them hitting full charge and the caps leaking below threshold to actually jump. Maybe higher TL caps are "less leaky" and thus able to be slow charged.

Or, simply, fast charge is SOP. It's the most efficient time v dollar scenario for most ship actions, etc. No one wants their jump drive taking a week to charge.

Who knows.

 

[rancke]

that avoided the question
What is the canon energy requirements for entering jump space?
in SI units, if you please....

if its unknown or unstated, just say so.

It's unknown, but whatever it is, you need (in the case we're discussing) fuel taking up 50% of the ship's tonnage to provide whatever it is.

guesstimating based on fuel tankage that would be needed for regular jump doesn't count unless you can state either "All jump fuel is used to produce energy" or "X% of jump fuel is used to produce energy and the rest is used for 'blahblahblah'".

Yes, it does count, because whatever the fuel is used for, you need to use 50% of the ship's tonnage to carry it.


Hans

 

[rancke]

Which two things in conflict are you referring to?

In this case, the tonnage you need to dedicate to performing jumps by the conventional means and the tonnage you need to dedicate to performing jumps if the information about the Annic Nova is accurate.

Are you saying the MWM endorsed Jump Masking, or GT, in total, and in general. It would be hard to imagine MWM not endorsing GT as a whole.

I'm saying that the writers asked Marc Miller about the implications of his jumpspace article and he informed them that jump masking was one of them.

Perhaps Jump Caps are "leaky" and a normal power plant can't charge them fast enough to overcome the leakage, but in "burn, baby, burn" mode, it can overcome the leakiness of the caps enough to fill them, and then you have a window between them hitting full charge and the caps leaking below threshold to actually jump. Maybe higher TL caps are "less leaky" and thus able to be slow charged.

The capacitors in the Annic Nova is supposedly able to hold the charge for weeks.

Or, simply, fast charge is SOP. It's the most efficient time v dollar scenario for most ship actions, etc. No one wants their jump drive taking a week to charge.

Just because it takes half a week (two jump drives on the Annic Nova, remember) to recharge a capacitor using solar panels doesn't mean it will take half a week to do so using a fusion power plant. And if you can do it with something that takes up 5% of volume instead of 50%, you increase the payload significantly. Spending three days to recharge would be well worth it.

It's true that there are several possible assumptions that can be made. But if every assumption leads to a contradiction, that doesn't really matter.

Oh, and there's also the canonical background information that the rifts are significant barriers to travel. If capacitors like the Annic Nova's actually existed, that would not be true.


Hans

 

[shadowcat20]

OK, just to throw out some numbers.

HG* says ship lasers take 1 EP to power and Fusion and Plasma take 2 EP
Striker** says a Ship laser is 250 MW and a Ship Fusion gun is 500 (They only give 250MW for the plasma gun so I figure it is not as effective with power use). It seems reasonable to assume a EP is 250 MW.

* page 25 in the Turret Weapons chart.
** Book 2 page 41.

High Guard page 31 states a ton of capacitors holds 36 EPs or 9000 MW (9GW?) Caps equil .5% of the ships mass times the Jump Number (Same Page).

So a 100 ton J2 ship would require 1 ton of caps or 9000 MW to jump.

Plus 20 tons of LHyd......

EDIT:Also the recharge rate of the Annic Nova would be dependant on distance from and size of the star they are recharging off of. In Rift space there would be no close energy sources so charging times would be VERY long.