The Expanse and its compatibility with OA

[Drashner1]

I'd need to see which ships are specifically being referred to, but as a first approximation:

a) OA uses droplet radiator systems a good bit, so the radiators may be folded away when the ship is not under power and so not visible.

b) A sufficiently advanced drive in OA may use magmatter components which are effectively immune to any amount of waste heat the drive can produce, making radiators either much smaller or not needed. There is also an ongoing and occasional mention of neutrino cooling in the setting, although the canonicity and details of that is often debated.

c) OA is a project that is largely built on the evolution of ideas, including in its artwork. As such, earlier items may not include things because they weren't thought of at the time or because our conception of things has shifted and/or matured over time. Almost nothing in the setting has sprung into existence fully formed and then never had a need to be updated (those bits that appear to date from the start of the project without updating probably need it but have either been overlooked or we haven't gotten around to them yet - letting us know about an issue is usually the quickest way to resolve such a thing).

Todd

[AstroChara]

I'd need to see which ships are specifically being referred to, but as a first approximation:

a) OA uses droplet radiator systems a good bit, so the radiators may be folded away when the ship is not under power and so not visible.

b) A sufficiently advanced drive in OA may use magmatter components which are effectively immune to any amount of waste heat the drive can produce, making radiators either much smaller or not needed. There is also an ongoing and occasional mention of neutrino cooling in the setting, although the canonicity and details of that is often debated.

c) OA is a project that is largely built on the evolution of ideas, including in its artwork. As such, earlier items may not include things because they weren't thought of at the time or because our conception of things has shifted and/or matured over time. Almost nothing in the setting has sprung into existence fully formed and then never had a need to be updated (those bits that appear to date from the start of the project without updating probably need it but have either been overlooked or we haven't gotten around to them yet - letting us know about an issue is usually the quickest way to resolve such a thing).

Todd

a) droplet radiators! Those are awesome things. Though, I think I've heard of this concept about 'dusty plasma' radiators that seems to be good as well, although I haven't looked into the details yet.

b) for this conversation, I'm referring only to 'near future' ships.

c) To be honest, thermodynamics isn't really a new idea, but I do admit it can easily be forgotten.

As for your question of which ship, the first thing that came to mind is the Starlark. This is a pic of it accelerating in Steve Bower's Starlark with what I assume to be an on-board drive, yet no red hot radiators were shown. Others are such as perhaps most, if not all early interstellar ships in the setting.

Unless if the OA engineers had found a way to redirect the nasty neutron away from hitting the ship early in the setting (on ToughSF's Discord server, somebody had made a concept on how to direct reaction neutron, I think it was by making sure the fusing atoms' orientation are just right, but I don't know the details), the radiator area is going to be quite big. That, and the drive has to be placed some distance away from the radiation shield.

I would've mentioned many ships from later in the timeline as well, but well, neutrino coolers. Ship designs after the early interstellar era are really beyond me.

[Noclevername]

a) droplet radiators! Those are awesome things. Though, I think I've heard of this concept about 'dusty plasma' radiators that seems to be good as well, although I haven't looked into the details yet.

...

Unless if the OA engineers had found a way to redirect the nasty neutron away from hitting the ship early in the setting (on ToughSF's Discord server, somebody had made a concept on how to direct reaction neutron, I think it was by making sure the fusing atoms' orientation are just right, but I don't know the details), the radiator area is going to be quite big. That, and the drive has to be placed some distance away from the radiation shield.

I'd suggest a combination of retractable radiators, which would start with droplets/dust (perhaps held in circulation patterns by invisible magnetic/plasma fields) and become made of increasingly advanced metamaterials, and then the neutron director by the time of the early interstellar ships.

[Drashner1]

a) droplet radiators! Those are awesome things. Though, I think I've heard of this concept about 'dusty plasma' radiators that seems to be good as well, although I haven't looked into the details yet.

They are indeed I've haven't heard of dusty plasma radiators - a bit of quick googling indicates that they might work even better than droplet radiators (potentially anyway - although some droplet designs also use magnetic fields to keep everything together - but plasma is just so much fun).

b) for this conversation, I'm referring only to 'near future' ships.

Ok

c) To be honest, thermodynamics isn't really a new idea, but I do admit it can easily be forgotten.

To clarify - In the early days of the OA project, images were much harder to come by and the editorial standards were more relaxed. Things have gotten better and stricter on both fronts, which helps with newer images. At the same time, our strong pack rat tendencies tend to make cycling older images out a more difficult process. It does happen, but it usually takes time unless someone takes it upon themselves to push the issue (not fight over it, but bring it up on a case by case basis and keep it top of mind).

As for your question of which ship, the first thing that came to mind is the Starlark. This is a pic of it accelerating in Steve Bower's Starlark with what I assume to be an on-board drive, yet no red hot radiators were shown. Others are such as perhaps most, if not all early interstellar ships in the setting.

Since Steve is active on the forum I'll leave it to him to address the Starlark issue. For other ships, I suppose it would depend on the earlier image factor I mentioned or whether the ship is under power. In some cases, it may be time to archive the current image and replace it with something more realistic. Certainly something we can discuss and if you come across other images that are problematic, please post about them here.

Unless if the OA engineers had found a way to redirect the nasty neutron away from hitting the ship early in the setting (on ToughSF's Discord server, somebody had made a concept on how to direct reaction neutron, I think it was by making sure the fusing atoms' orientation are just right, but I don't know the details), the radiator area is going to be quite big. That, and the drive has to be placed some distance away from the radiation shield.

D-He3 fusion (and p-B as well IIRC) is supposed to produce a much lower neutron flux, so that might be part of the answer. That said, current OA canon for early ships is that they mainly use amat catalyzed fusion which presumably produces lots of gamma rays and possibly some large amount of neutrons.

Some factors that could impact things here are:

a) the performance of the ship - if the ship is only accelerating at .01 to .1 G (or less) it may not need much in the way of radiators. Same if it only accelerates for a time and then coasts most of the way.

b) For advanced radiators - just how big do they need to be. Some time back we were having a discussion around waste heat on reaction drive ships and droplet radiators. I came across a (now unfortunately taken down) page that purported to calculate the performance of a droplet radiator of a given capability and also provide its dimensions. The resulting numbers were amazingly small - which led us to distrust them to some degree. It would be nice if someone could figure out the size of a droplet radiator based on different assumptions - both to help with the relevant EG entries and with image creation.

On a different note - I wonder what, if any, role laser cooling might play in this sort of operation. The waste heat would still need to go somewhere eventually - but the resulting design might look very different from what we are used to. With a high power drive you could siphon off some amount of energy to power a lot of lasers.

Going really far afield in the speculation dept and taking a page from Niven's Ringworld - might you be able to arrange things so that the plasma of the ship exhaust lases in specific spots that fire onto the ship hardware to cool it? With the waste heat from the process ultimately shooting out the back of the ship into space? I suspect there are any number of reasons why this wouldn't work, but throwing it out there anyway - because every now and again I'm surprised and (to quote Clarke) - the only way to find the limits of the possible is to venture a little way past them into the impossible.

I would've mentioned many ships from later in the timeline as well, but well, neutrino coolers. Ship designs after the early interstellar era are really beyond me.

As I said, neutrino cooling is somewhat controversial around here. My preference would be to find other methods, at least for ships made of conventional matter. But be that as it may.

Ok, time to finish lunch and get back to work.

Todd

[Noclevername]

b) For advanced radiators - just how big do they need to be. Some time back we were having a discussion around waste heat on reaction drive ships and droplet radiators. I came across a (now unfortunately taken down) page that purported to calculate the performance of a droplet radiator of a given capability and also provide its dimensions. The resulting numbers were amazingly small - which led us to distrust them to some degree. It would be nice if someone could figure out the size of a droplet radiator based on different assumptions - both to help with the relevant EG entries and with image creation.

According to Children Of A Dead Earth's science-based simulations, hotter radiators can be smaller. There's crunchy numbers involved, but I'm the wrongest person to analyze them. 


Maybe the ships in question have radiators, but the pics are just "artist's recreations" that don't emphasize all the details.

[stevebowers]

The Starlark does have droplet radiators (I think they are mentioned in the blog) but they aren't deployed in that image yet. The good thing about droplet radiators is that they fold away before and after use.

[Noclevername]

Getting back to the Expanse, they might have the neutron aligner, and all their troubles flow out of their exhaust.

(Of course that makes their civilian ships that much more weaponized. Every torch is also a collimated particle beam.)

[AstroChara]

b) For advanced radiators - just how big do they need to be. Some time back we were having a discussion around waste heat on reaction drive ships and droplet radiators. I came across a (now unfortunately taken down) page that purported to calculate the performance of a droplet radiator of a given capability and also provide its dimensions. The resulting numbers were amazingly small - which led us to distrust them to some degree. It would be nice if someone could figure out the size of a droplet radiator based on different assumptions - both to help with the relevant EG entries and with image creation.

According to Children Of A Dead Earth's science-based simulations, hotter radiators can be smaller. There's crunchy numbers involved, but I'm the wrongest person to analyze them. 


Maybe the ships in question have radiators, but the pics are just "artist's recreations" that don't emphasize all the details.

But the radiators are a pretty important detail of the ship...

On radiator temperature: yes, exactly, you’ll want to run your radiators as hot as possible. If I remember (and write it) correctly, the radiator surface area required to reject an amount of heat is inversely proportional to power of four of temperature, so as you bump the temperature up, the surface area required gets down extremely fast.

On Starlark: I thought the radiators have to be on almost immediately after turning on the engine...

On droplet radiators: This Space Calc page might be useful.

[stevebowers]

On Starlark: I thought the radiators have to be on almost immediately after turning on the engine....

Yes, but they won't work when the ship is stationary, and aren't deployed in the first few minutes of flight. The first few gigawatts are used to heat some of the water propellant into steam, adding a small amount of added delta vee.

[Noclevername]

Maybe early ships had a common practice of carrying large, cheap drop tanks of ice? The pics could have been "taken" just after dropping them but just before deploying radiators in their place. It could perhaps have been so very common that it wasn't mentioned much in the historical literature, just as a driver starting his car doesn't think much about the components of his car's internal combustion engine and radiator every time.