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Post by srbrant on Jul 27, 2018 4:28:28 GMT
Exactly how big does a ship have to get before it becomes inefficient or even dangerous in any particular way? Is an armada of much smaller ships better than one very large vessel? How big can a ship get until it begins wasting propellant, becoming a serious collision danger to planets or taxing its own structural integrity?
To help answer the questions I'm looking for, here are some relevant details about my story's universe.
- New, exotic materials have been invented through fusion-based metallurgy (fancifully called "Neo-alchemy") and other processes, most of them being supertensile solids and fibers. Things like plasteel, arachnite, etc. - Fusion engines are closed-circuit and incredibly efficient; so much so that it consumes only half the propellant necessary. In fact, some ships have heavy aesthetic additions simple for the sake of increasing mass so that they don't approach relativistic speeds!
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Post by apophys on Jul 30, 2018 10:24:45 GMT
An armada of smaller ships has the clear benefits of redundancy and being able to split into multiple effective forces. A larger ship can carry thicker armor when everything about it gets scaled up. However, it requires more structural mass to maintain the same integrity under thrust. With MPD-tier accelerations, this isn't a significant concern, but it may be an issue for your fusion drives (depending on what you use, and whether you use classic rocket builds or tensile structures with the rockets in front, dragging the payload behind).
A larger ship requires larger radiators; at a certain point, heat transfer will require large flows of coolant across kilometers of piping, which may be a problem. A Curie point radiator may be able to alleviate that a bit.
At a certain point, you will start running out of surface area to mount thrusters. If you try to go bigger, you will need to do some creative designs for more surface area.
Wasting propellant seems more applicable to the very small ships (drones, really) that can't afford the minimum mass or power for efficient drives. Not a concern for most. Space is big. Avoiding collisions is pitifully easy (unless the target planet is affected by Kessler syndrome, and you need to pass through the debris belt for some inexplicable reason).
Large ships may have the benefit of longer-ranged weaponry. But this difference doesn't apply if you are able to make a phased array laser with an armada of small ships (which should be possible, and in a high-tech universe can be safely assumed).
TL;DR: There's no obvious choice between large and small. But it's justifiable to have all warships within 1-2 orders of magnitude of each other in mass.
In fact, some ships have heavy aesthetic additions simple for the sake of increasing mass so that they don't approach relativistic speeds! This makes no sense. At all.
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Post by Apotheon on Jul 30, 2018 12:00:58 GMT
In fact, some ships have heavy aesthetic additions simple for the sake of increasing mass so that they don't approach relativistic speeds! This makes no sense. At all. Is he insane, or so sane that you just blew your mind?
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Post by jtyotjotjipaefvj on Jul 30, 2018 12:11:42 GMT
The point is that there's never a reason to add dead mass to a spaceship. If you don't want to go as fast, you lift your foot off the gas pedal once you hit desired speed.
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Post by The Astronomer on Jul 30, 2018 12:29:17 GMT
...er, I don't think a fusion ship will go relativistic just because it is a fusion ship.
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Post by AtomHeartDragon on Jul 30, 2018 18:51:47 GMT
- Fusion engines are closed-circuit and incredibly efficient; so much so that it consumes only half the propellant necessary. If only half the propellant necessary is actually necessary then, by definition, the propellant necessary is not the propellant necessary because it's twice the propellant necessary.
The point is that there's never a reason to add dead mass to a spaceship. If you don't want to go as fast, you lift your foot off the gas pedal once you hit desired speed. The only possible reason to add dead mass to a spaceship is when you have more delta-v AND acceleration than you know what to do with, so you no longer give a flying fuck.
Given current RL and CoaDE's state of the art in spacecraft propulsion such a situation is nowhere in sight.
Anyway, the ships are as big as they need to be and not bigger.
You might want a bigger ship if: - It is needed to accommodate large singular components for some reason.
- It is needed to house your state of the art weapon or the powerplant it needs.
- It allows you to remove redundancies created by housing different parts of your fleet's equipment on their dedicated ships.
- Your best space-drive doesn't scale down very well.
- You benefit more from armour than from manoeuvrability or throwing more targets at the enemy or simply need certain minimum armour thickness.
You might want a smaller ship if: - Acceleration or having spare ships is the best armour you have.
- Spreading out is tactically or strategically important.
- You have limited resources.
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Prancer
Junior Member
Jousting in space. We're all Knights of the Stars.
Posts: 57
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Post by Prancer on Jul 30, 2018 22:20:54 GMT
Large ships may have the benefit of longer-ranged weaponry. But this difference doesn't apply if you are able to make a phased array laser with an armada of small ships (which should be possible, and in a high-tech universe can be safely assumed). Correct me if I'm wrong, but by a phased-array laser with multiple small ships, are you saying that say a four-ship flight of laser ships could somehow merge their lasers together into a single more powerful laser??? I'm guessing that the weapons would have to be purpose-built for this. Would they retain utility as stand-alone laser weapons? How?
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Post by The Astronomer on Jul 31, 2018 0:38:55 GMT
Large ships may have the benefit of longer-ranged weaponry. But this difference doesn't apply if you are able to make a phased array laser with an armada of small ships (which should be possible, and in a high-tech universe can be safely assumed). Correct me if I'm wrong, but by a phased-array laser with multiple small ships, are you saying that say a four-ship flight of laser ships could somehow merge their lasers together into a single more powerful laser??? I'm guessing that the weapons would have to be purpose-built for this. Would they retain utility as stand-alone laser weapons? How? I guess you can just point them all at the same target.
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Post by apophys on Jul 31, 2018 3:07:18 GMT
Correct me if I'm wrong, but by a phased-array laser with multiple small ships, are you saying that say a four-ship flight of laser ships could somehow merge their lasers together into a single more powerful laser??? I'm guessing that the weapons would have to be purpose-built for this. Would they retain utility as stand-alone laser weapons? How? I guess you can just point them all at the same target. Not quite so simple as just pointing them at the same target; that would only multiply your intensity, with the same spread. You get a much tighter focus if all the laser light is additionally in phase; it is comparable to having a single larger aperture of equal area. This affects your weapon's (or weapon array's) effective range.
See here for a visual comparison for a phased array:
Yes, the individual laser ships would retain their utility as standalones, and you wouldn't need any specific number of ships either (5 or 5,000 work just as well).
The array as a whole doesn't get totally ruined by any one of them being slightly off.
You can include laser ships of different sizes if you please.
The ships in the array do have to all be the exact same wavelength of laser to make the array.
The technical challenges to be overcome are significant, but within a few decades' reach. It only works properly when the wavefronts overlap constructively at the target; in other words, you need a precision notably less than a wavelength for your phase, for every element in the array. Note that this means you have a tolerance in the scale of nanometers at best. Very difficult to achieve for unconnected, separately drifting spaceships.
Current phased array lasers are built as a bunch of physically connected lasers, and they don't move in relation to each other while firing. In order to make the technological jump, it will probably be necessary to use laser interferometry to precisely measure the distances between the spaceships in the array, use software to generate a 3-D model of the array with each ship as a vertex, and dynamically modify the output phase of the lasers accordingly with proper prediction software.
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Post by Fgdfgfthgr on Jul 31, 2018 4:17:50 GMT
If only half the propellant necessary is actually necessary then, by definition, the propellant necessary is not the propellant necessary because it's twice the propellant necessary.
What?
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Post by Anon1 on Jul 31, 2018 5:45:31 GMT
You could build a ship the size of a planet if you wanted to, but its acceleration would be crap. At around 10 to 20 billion metric tons, you have a ship capable of carrying enough nuclear ordnance to trigger a global extinction level event. I don't know why you would need to build a warship bigger than that. Now generation ships or mobile bases could reasonably be built larger; but once you get to Death Star 1 size, then there is really no need to build anything bigger.
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Post by AtomHeartDragon on Jul 31, 2018 6:51:08 GMT
Now generation ships or mobile bases could reasonably be built larger; but once you get to Death Star 1 size, then there is really no need to build anything bigger. What if you want to use Shkadov thruster as your propulsion?
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Post by AtomHeartDragon on Jul 31, 2018 17:58:51 GMT
Regarding phased array lasers - they have one other advantage. Given that they are effectively large areas covered by repeating tiny emitters, they are going to be quite damage tolerant and easy to cool.
They have a number of disadvantages as well - exposing tiny, very precise machinery on the surface renders it very vulnerable to micrometeorite, thermal and radiation damage.
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Prancer
Junior Member
Jousting in space. We're all Knights of the Stars.
Posts: 57
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Post by Prancer on Jul 31, 2018 20:26:59 GMT
I imagine mutli-ship phased array lasers would then have a limit to how much space they could practically cover in a dynamic battlefield, and as a result how many ships of a certain size could participate. Since light-speed lag would probably mean precise control becomes impractical past a certain distance.
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Post by AdmiralObvious on Aug 1, 2018 1:26:42 GMT
If your ship doesn't have a radius bigger than the sun's diameter it ain't big enough.
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