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The Expanse technical thread

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Rune    4361
Posted (edited)
On 11/2/2016 at 5:51 AM, mikegarrison said:

What does it look like to walk around in low G without a spacesuit? Because, you know, I've never seen it.

The humans don't have any artificial gravity in this show. They only have spin gravity and acceleration gravity. Which brings me to the interior set of the Roci, which is all wrong. In the set they walk horizontally to the different parts of the ship, but the ship is actually built like a layer cake and they should be climbing ladders to get to the different areas of the ship.

Actually, the Roci has several decks on top of each other,  connected with stairs which are quite obvious in a lot of scenes. And of course the cargo bay is down, under engineering, which should be pretty obvious some time on season 2/3. :wink:.

The show makes a damned good effort to respect science... except in its basic premises, like the Epstein drive. The plume power in those things is totally torch-like, and they completely miss the implications: cheap torchships mean cheaper relativistic missiles, and then why the hell would you build nukes.

 

Rune. Which is why this show is an amazing piece of space opera.

Edited by Rune

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Codraroll    298
1 hour ago, Rune said:

The plume power in those things is totally torch-like, and they completely miss the implications: cheap torchships mean cheaper relativistic missiles, and then why the hell would you build nukes.

Because a relativistic missile will still only affect targets that perfectly cross its path. Miss by ten metres, and you might as well have missed by ten thousand kilometres. You can't take out two ships with one missile without a warhead, or destroy a target that narrowly dodges out of the missile's path. A path that will be very predictable, by the way, if the missile is travelling on a ballistic trajectory.

Plus, I'd imagine that the Epstein drive is expensive and complicated enough that outfitting the missile with a warhead is trivial by comparison. You might as well slap one on there.

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hms_warrior    71
Posted (edited)
1 hour ago, Rune said:

and then why the hell would you build nukes.

Not exactly arguing against you here, but a shaped nuclear charge might have a few hundred metres of killrange while a kinetic-kill-missle needs a direct hit. Against ships that can pull 15gs, have active CM and anti-missle lasers that might be still useful.

Edited by hms_warrior

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Nikolai    180
On 1/8/2017 at 5:54 AM, Codraroll said:

It's been a while since I read the relevant book, but I seem to recall that it took several decades for them to spin up Ceres, and that it's been hailed as the greatest engineering achievement in history. And they started with it long after the Epstein drive was invented.

Even so -- even with decades and Epstein Drives and people saying "Gee whiz" -- if physics ruins a show for you, don't calculate how much energy this would take.

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Rune    4361
37 minutes ago, Codraroll said:

Because a relativistic missile will still only affect targets that perfectly cross its path. Miss by ten metres, and you might as well have missed by ten thousand kilometres. You can't take out two ships with one missile without a warhead, or destroy a target that narrowly dodges out of the missile's path. A path that will be very predictable, by the way, if the missile is travelling on a ballistic trajectory.

Plus, I'd imagine that the Epstein drive is expensive and complicated enough that outfitting the missile with a warhead is trivial by comparison. You might as well slap one on there.

I meant in the grander socioeconomic scheme of things: any bozo in the belt with access to a drive can blow up, say, North America if he is feeling like it. And I know the show kind of implies the belters threaten to drop rocks every now and then, but it's not like anybody realizes they can just as well blow up any fixed installations, and they don't need the rocks in their first place, just the drives on their ships. Why do they cower in fear? Why do Earth and Mars require building more warships to maintain the power balance? They are in the ultimate MAD situation just using widespread civilian equipment. But still they tip their interplanetary missiles with nukes. :rolleyes:

However, I forgive them, because as I said this is space opera, and all the timelines are very compressed, with events happening all over the place witnessed by the same people. I just think a x10 on the travel timeline and limiting the drives to "standard" fusion-like performances would turn this into much harder sci-fi. I know that thrust gravity over long periods is a very cool concept, but is it worth the price? Because with it, everybody would have in their hands a pretty acceptable starship-drive-slash-ultimate-doomsday-weapon.

Oh, and let it be known: you are both 100% correct on the implications for spaceship combat.

 

Rune. The lesson here: mind your drive implications when story-building.

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mikegarrison    797
1 hour ago, Codraroll said:

Plus, I'd imagine that the Epstein drive is expensive and complicated enough that outfitting the missile with a warhead is trivial by comparison. You might as well slap one on there.

As I recall from the books, a ship the size of the Roci was the very smallest that could have one of these Epstein drives. Anything smaller had to have a more conventional reaction drive (which they called a "teakettle drive").

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StarStreak2109    333
4 hours ago, mikegarrison said:

As I recall from the books, a ship the size of the Roci was the very smallest that could have one of these Epstein drives. Anything smaller had to have a more conventional reaction drive (which they called a "teakettle drive").

Wasn't the tea kettle drive some kind of RCS with superheated steam? And for the "normal" drives they always spoke of "fusion torch drives"?

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Tyko    536
2 hours ago, StarStreak2109 said:

Wasn't the tea kettle drive some kind of RCS with superheated steam? And for the "normal" drives they always spoke of "fusion torch drives"?

Yea, I think the same thing..."tea-kettling" was described in the first book as using steam to push ships around (hence the tea kettle reference) and sounded like it's only usually used over short distances. I equated it to RCS. I'm not sure they ever said what heated the steam, but fusion plants seem to be the heater of choice for most things.

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peadar1987    909
8 hours ago, Rune said:

I meant in the grander socioeconomic scheme of things: any bozo in the belt with access to a drive can blow up, say, North America if he is feeling like it. And I know the show kind of implies the belters threaten to drop rocks every now and then, but it's not like anybody realizes they can just as well blow up any fixed installations, and they don't need the rocks in their first place, just the drives on their ships. Why do they cower in fear? Why do Earth and Mars require building more warships to maintain the power balance? They are in the ultimate MAD situation just using widespread civilian equipment. But still they tip their interplanetary missiles with nukes. :rolleyes:

However, I forgive them, because as I said this is space opera, and all the timelines are very compressed, with events happening all over the place witnessed by the same people. I just think a x10 on the travel timeline and limiting the drives to "standard" fusion-like performances would turn this into much harder sci-fi. I know that thrust gravity over long periods is a very cool concept, but is it worth the price? Because with it, everybody would have in their hands a pretty acceptable starship-drive-slash-ultimate-doomsday-weapon.

Oh, and let it be known: you are both 100% correct on the implications for spaceship combat.

 

Rune. The lesson here: mind your drive implications when story-building.

Earth and Mars build warships to maintain the power balance for the same reason the USA and USSR kept building tanks and guns after ICBMs were invented. Neither was going to escalate things to a full nuclear exchange if they could have avoided it. If you're scrambling for influence over resources in the Belt, a warship is going to be a lot more use than going straight to scorching the surface of the earth.

Spoiler

In Nemesis Games, the reason the Belters dropped rocks was for stealth. I'd assume that the earth has a pretty robust system for obliterating any threats that it knows about.

 

Edited by peadar1987

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Gkirmathal    24
On 10-1-2017 at 1:00 AM, Tyko said:

Yea, I think the same thing..."tea-kettling" was described in the first book as using steam to push ships around (hence the tea kettle reference) and sounded like it's only usually used over short distances. I equated it to RCS. I'm not sure they ever said what heated the steam, but fusion plants seem to be the heater of choice for most things.

Haven't read the proloque yet regretfully. But I understood the 'tea-kettle' drives where, as a plot mechanic, fusions reactors where the plasma exhaust was fed 'a' reaction mass (water/LH2/NH3/etc). Giving about the same thrust levels as an Epstein, but far far less Dv.

Remember reading in one of the books those 'tea-kettle drives' where the technical norm for propulsion in the early days, when humanity started to colonise Mars and the belt. The were only used for orbital insertions/escape and the rest of the journey the ships coasted.

Edited by Gkirmathal

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mikegarrison    797
5 hours ago, Gkirmathal said:

Haven't read the proloque yet regretfully. But I understood the 'tea-kettle' drives where, as a plot mechanic, fusions reactors where the plasma exhaust was fed 'a' reaction mass (water/LH2/NH3/etc). Giving about the same thrust levels as an Epstein, but far far less Dv.

Remember reading in one of the books those 'tea-kettle drives' where the technical norm for propulsion in the early days, when humanity started to colonise Mars and the belt. The were only used for orbital insertions/escape and the rest of the journey the ships coasted.

Yes. Like I said, the "tea kettle" drive was basically what we have today. A reaction rocket in which thrust and ISP tend to be mutually exclusive. Due to the prevalence of cheap nuclear reactors in the Expanse universe, they were nuclear thermal rockets. Get a reactor hot, dump some water (or similar) onto it, get a bunch of hot exhaust, and direct it out as a rocket.

In contrast, the Epstein drive is pure plot magic (and admitted as such by the authors). It is a fusion-powered reaction drive, but it is magically so high in ISP that you can run a high thrust engine for as long as you want without having to carry a huge amount of reaction mass. Supposedly it was invented by a mad scientist named Epstein as a hobby, who used it to launch himself into interstellar space forever. But luckily for everyone else, he left behind the schematics.

It was stated in the first book that the Roci was just about as small as a ship could be and still have the Epstein drive. Anything smaller, like the Canterbury's shuttle that our crew is stuck in at the start of the book, has only the tea kettle drive.

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Tyko    536

O

1 hour ago, mikegarrison said:

Yes. Like I said, the "tea kettle" drive was basically what we have today. A reaction rocket in which thrust and ISP tend to be mutually exclusive. Due to the prevalence of cheap nuclear reactors in the Expanse universe, they were nuclear thermal rockets. Get a reactor hot, dump some water (or similar) onto it, get a bunch of hot exhaust, and direct it out as a rocket.

Here's what Leviathan Wakes says:

"Flying teakettle was naval slang for flying on maneuvering thrusters that used superheated steam for reaction mass."

This is RCS, but instead of drawing from a tank of compressed gas or using a chemical reaction, they're superheating water. So, yes it's basically tiny NTRs or heating elements drawing power from a central point in the ship.

Edited by Tyko

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Tyko    536

On a side note, I am still watching through Season 1 and I keep getting really annoyed with stupid oversights...for example, in the most recent episode, I watched as the Roci departed Tycho Station. They used RCS to push about a ship-length from the station, turned tail toward the station and lit their fusion drive...They entire side of the station would have been destroyed.

Edited by Tyko

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mikegarrison    797
1 hour ago, Tyko said:

O

Here's what Leviathan Wakes says:

"Flying teakettle was naval slang for flying on maneuvering thrusters that used superheated steam for reaction mass."

This is RCS, but instead of drawing from a tank of compressed gas or using a chemical reaction, they're superheating water. So, yes it's basically tiny NTRs or heating elements drawing power from a central point in the ship.

Yes -- if your ship has an Epstein drive, you only use the NTR for maneuvering thrusters. But when they talk about trying to self-rescue after the Canterbury is destroyed, you find out that their shuttle's main drive is also "teakettle".

At least, that's how I remember it. If you have the book at hand, you could confirm or correct this.

1 hour ago, Tyko said:

On a side note, I am still watching through Season 1 and I keep getting really annoyed with stupid oversights...for example, in the most recent episode, I watched as the Roci departed Tycho Station. They used RCS to push about a ship-length from the station, turned tail toward the station and lit their fusion drive...They entire side of the station would have been destroyed.

Possibly. But since there really are no details on how the Epstein drive works....

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Tyko    536
1 hour ago, mikegarrison said:

Possibly. But since there really are no details on how the Epstein drive works....

There's nothing to suggest it's reactionless and the giant glowing engine bell pointing out the back - plus the fact that the Roci has to take on reaction mass occasionally throughout the books - suggests it's still throwing mass out of the back to make it go forward. If it is throwing mass out, it all would have been impacting the side of the station at 100 meters or so. Given how quickly the Roci accelerated away from the station, it was also throwing mass pretty vigorously.

the writers acknowledge that the Epstein drive isn't fully realistic, but the variations seem to be in terms of power output and ISP rather than some sort of magical Star Trek drive or something.

1 hour ago, mikegarrison said:

Yes -- if your ship has an Epstein drive, you only use the NTR for maneuvering thrusters. But when they talk about trying to self-rescue after the Canterbury is destroyed, you find out that their shuttle's main drive is also "teakettle".

At least, that's how I remember it. If you have the book at hand, you could confirm or correct this.

" Flying teakettle was naval slang for flying on maneuvering thrusters " - this is a direct quote from the book. So there's no such thing as a teakettle drive, it's just a reference to using maneuvering thrusters instead of engaging the main fusion drive.

EDIT...below more info on the Epstein drive from the Expanse Wiki. Assuming this is the author's intent, it's pretty clear that it's just a really efficient reaction drive.

The drive utilizes magnetic coil exhaust acceleration to increase drive efficiency, which enables spaceships to sustain thrust throughout the entire voyage. A ship fitted with the efficient Epstein drive is able to run the drive continuously for acceleration to its goal and then after flipping at about the halfway point is able to run the drive continuously during deceleration. Previous engine designs used propellant less efficiently and could not be run long enough to achieve the high velocities that the Epstein drive permitted

Edited by Tyko

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mikegarrison    797
57 minutes ago, Tyko said:

" Flying teakettle was naval slang for flying on maneuvering thrusters " - this is a direct quote from the book. So there's no such thing as a teakettle drive, it's just a reference to using maneuvering thrusters instead of engaging the main fusion drive.

Tyko, I'm not going to post on this again. It's a waste of time to argue about fictional technologies.

But you clearly have not paid attention to what I said. I believe your quote from the book is not the full context. I mentioned a case where the main drive of a ship was "teakettle" and you continue to ignore that.

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Tyko    536
45 minutes ago, mikegarrison said:

Tyko, I'm not going to post on this again. It's a waste of time to argue about fictional technologies.

But you clearly have not paid attention to what I said. I believe your quote from the book is not the full context. I mentioned a case where the main drive of a ship was "teakettle" and you continue to ignore that.

:) this is all a friendly dialog. I'm doing my best to find and provide references to published info - the books themselves or the official wiki. I'd really appreciate it you found the reference you're referring to so we could both better understand the author's intent.

Edited by Tyko

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kerbiloid    2098

Isn't the mentioned Epstein engine just kinda EmDrive on steroids?
A bell-shaped nozzle throwing nothing, utilizes magnetic coil, with enormous ISP.

Edited by kerbiloid

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SargeRho    277
2 hours ago, kerbiloid said:

Isn't the mentioned Epstein engine just kinda EmDrive on steroids?
A bell-shaped nozzle throwing nothing, utilizes magnetic coil, with enormous ISP.

No, the Epstein Drive is basically a particle accelerator-boosted Fusion drive.

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Diche Bach    158

Still no clarification on why they need the "ice" that is mined from (aparently) Saturn's rings on "Ceres?"

Only up to episode 3 but wife and I are enjoying it. Realistic science fiction wouldn't be very fun to watch I think.

Edited by Diche Bach

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SargeRho    277
1 hour ago, Diche Bach said:

Still no clarification on why they need the "ice" from (aparently) Saturn's moons on "Ceres?"

Only up to episode 3 but wife and I are enjoying it. Realistic science fiction wouldn't be very fun to watch I think.

Ceres has been stripped of its ice, and is now a dry rock. The ECLSS on Ceres isn't 100% air- and water tight, and water is probably also used to produce fuel for chemical thrusters.

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DDE    604

THIS IS BLASPHEMY! NOBODY LINKED THIS VID YET!

3 hours ago, SargeRho said:

Ceres has been stripped of its ice, and is now a dry rock. The ECLSS on Ceres isn't 100% air- and water tight, and water is probably also used to produce fuel for chemical thrusters.

A lot of their drives use water as reaction mass. They're using a lot of it irreversibly.

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mikegarrison    797
10 hours ago, Diche Bach said:

Realistic science fiction wouldn't be very fun to watch I think.

I think you are confusing realism with lack of a plot. But since there is no accepted boundary for what is and is not science fiction, I suppose it could be claimed that anything completely realistic isn't science fiction at all.

I will certainly say that for most stories, a desire to be 100% realistic is very constraining. Probably this is because fiction, by it's nature, is unreal, and so trying to write "realistic fiction" is actually an attempt to create something that is "realistically unreal" -- a difficult task.

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Gkirmathal    24

Really a wonderful video by Scott Manley's, gave much to talk about with friends who also follow the Expanse. Good stuff!

---

Done some digging regarding the confusion about "teakettling" vs RCS propulsion. Teakettling has to do with steam, but not with RCS propulsion.

In book 5 Nemesis Games, I won't spoiler the story, a ship will be used for a couple of chapters in the plot. The ship itself dates back to the pre-epstein era, an oltimer so to say. It's main drive is an old style fusion-torch-drive (stuff like described on Projectrho site).

The ship mentioned in book 5 needed to 'coast from A to B', due to it's fusion drive, leaving the crew in zero-g for most of the trip.

It ran on it's fusion plasma only (high efficiency/low thrust), or augmented with a reaction mass (more thrust/much lower efficiency). This oldskool fusion propulsion was mentioned as a teakettle drive (a short description was also given in book one if i'm not mistaken)

---

Way back The Expanse started out as a tabletop rpg and that made me wonder what other games besides KSP are in the making.

Since I began reading the books, I have been looking for a new Sci/fi game which combines the Expanse in feel, scope and in technological development, with KSP like features.

A game like: KSP's ship construction/design, proper Newtonian physics, a large (full) scale solar system to explore, trade and walk around in. But not orientated on building/launching rockets, like in KSP.

I haven't been able to find any title besides KSP that checks most boxes. Most titles have unrealistic physics, submarine ship design, or artificial gravity mumbo-jumbo/propulsion/etc. Helion and Helium Rain seem to come close, though both have also have elements I really dislike.

KSP's 'realism' can really spoiled you :P, so is there anyone else who is looking for a similar type of game and know of something in development at this moment?

 

Edited by Gkirmathal

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Spaceception    2731

I can't wait to see the forth book on screen, that will be flippin' amazing!

23 minutes ago, Gkirmathal said:

Done some digging regarding the confusion about "teakettling" vs RCS propulsion. Teakettling has to do with steam, but not with RCS propulsion.

In book 5 Nemesis Games, I won't spoiler the story, a ship will be used for a couple of chapters in the plot. The ship itself dates back to the pre-epstein era, an oltimer so to say. It's main drive is an old style fusion-torch-drive (stuff like described on Projectrho site).

The ship mentioned in book 5 needed to 'coast from A to B', due to it's fusion drive, leaving the crew in zero-g for most of the trip.

It ran on it's fusion plasma only (high efficiency/low thrust), or augmented with a reaction mass (more thrust/much lower efficiency). This oldskool fusion propulsion was mentioned as a teakettle drive (a short description was also given in book one if i'm not mistaken)

 

I just finished book 5 yesterday :D

Anyway, I feel it's pretty realistic, if you ignore the Epstein.

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