10-19-2019, 07:18 AM | #1 |
Hero of Democracy
Join Date: Mar 2012
Location: far from the ocean
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Spaceship Weapons and Gravity Layout
I'm laying out a super-science battleship for a damage control scenario, which gets more into the nitty-gritty of the ship than many other activities, and I could use some advice on how to lay the ship out.
The ship will be using artificial gravity. This is generated by grav-disks that apply either an attractive or a repulsive force to each side in a symmetric cylinder centered on the disk. Stacking a disk on each level requires changing the direction of gravity each time you pass a plate, which seems undesirable (likely at least 6 decks, if not more). I'm thinking the ship should be long and thin so that it can present a minimal profile to opponents. I'm tentatively sticking the engines (super-science boosted reaction engines) on the other side of the minimal profile. I'm unsure if I should orient the gravity down towards the engines, so the ship is built like a rocket or sky scraper, or if I should pick a long side of the ship to be "down", and orient the thing like a naval ship. The rocket orientation makes thrust and artificial gravity stress in the same direction, but gives a single point of failure for artificial gravity. It makes it easier to put gravity over the whole ship, but I'm not sure if that is a good thing or not. Conversely, the naval orientation looses gravity in chunks, rather than all at once, but doesn't line up with the thrust and is likely to result in corners of microgravity. Microgravity in the ship is considered a bad thing: most the crew is only passably trained for it, and when the gravity gets turned off all sorts of things come loose on a lived in ship. Does anyone have idea on how to arrange backup gravity systems? The assumption is if the gravity is out its because the grav-disk generating it has been hit, so a nearby backup isn't an option. I'm trying to figure out the layout of the guns. My two initial ideas are putting the main turrets all on one long side of the ship, sloped towards the front. This is to allow the ship to concentrate fire in one direction. The other option is to slope all of the sides towards the front and place the main turrets all the way around the ship. Point defense guns will need to be fairly evenly distributed around the ship, though putting extra in the same direction as the main turrets is likely a good idea. I'm also unsure if there is is a benefit to orienting turrets in a specific direction with regards to gravity. The ship has shields, so armor layout isn't as important as it might be, though structural integrity and relative compactness is still nice. And the ship will still be getting hit. What am I missing? How would you lay out the ship? Thanks for the advice!
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10-19-2019, 07:54 AM | #2 | |||
Join Date: Aug 2004
Location: traveller
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Re: Spaceship Weapons and Gravity Layout
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If your reaction engine system allows (e.g., doesn't spew radioactive death), it is helpful to place the main engines closer to amidships and make the hull a double cone. This reduces stress on the hull by reducing the "height" from the drive plane, and makes the ship easier to turn. You would need secondary batteries for the rear arc, but now you have some surface area to mount them. You could also have room for (e.g.) launching and recovering small craft without entering the main battery's firing arc. |
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10-19-2019, 08:21 AM | #3 | |||
Hero of Democracy
Join Date: Mar 2012
Location: far from the ocean
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Re: Spaceship Weapons and Gravity Layout
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It might also be interesting to mount the main gravity plate of a skyscraper layout in the middle of this ship, having the effective height. You have to switch gravity orientation once, but that might not be a big deal. A bigger deal might be that you can't easily thread things like pipes, power conduits, and passageways through the disk, Though I could embrace using lots of smaller disks rather than one big one.
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Be helpful, not pedantic Worlds Beyond Earth -- my blog Check out the PbP forum! If you don't see a game you'd like, ask me about making one! |
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10-19-2019, 09:35 AM | #4 |
Join Date: Nov 2015
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Re: Spaceship Weapons and Gravity Layout
What kind of force do those disks provide? And what about your engines?
And skyscraper is your only option really, unless you want ppl slamming against the walls every time your ship accelerated. And ofc if your disks provide a fixed 1G, you still have problems |
10-19-2019, 09:44 AM | #5 |
Join Date: Jun 2013
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Re: Spaceship Weapons and Gravity Layout
For gravity backups, having attractor-repulsor pairs at opposite sides of the ship could work. With the naval orientation, for example, you could have an array of attractor disks in the ventral portion of the ship, with a corresponding array of repulsor disks in the dorsal portion. For the crew, the attractive and repulsive forces would be in the same direction (“down”) and would probably be indistinguishable from each other. Up to you if you want both to generally be “on” (and thus loss of one cuts gravity in half, potentially adjustable back up to full) or if you want to have one always on and the other to turn on only when needed (so loss of one either has no effect or causes a brief few moments of zero G before the backup turns on). You should be able to manage a similar scheme with the rocket orientation as well.
Also, unless loss of gravity is unlikely without leading shortly to the destruction of the ship, the crew should be well-trained for zero G, and SOP should be to secure any loose tools/etc as soon as one is done using them (built-in electromagnets to let you stick it to any nearby metal surface when not in use would be useful). The skills are too important in space to neglect, and training isn’t exactly difficult when you’re already in space (just shut off the gravity to train).
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10-19-2019, 09:44 AM | #6 |
Join Date: Sep 2007
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Re: Spaceship Weapons and Gravity Layout
Skyscraper orientation aligns the gravity direction with the thrust direction. So, if you give the gravity generators sensors (or connect them to the engine controls; either way gives you more stuff to break and thus have to fix to get the gravity under control), you can automatically reduce the gravity as the thrust increases, or even flip the orientation of the gravity vector (if the tech allows) to counter thrust over 1G. If it's naval-ship orientation, with the "rockets" oriented out the "stern", then any significant thrust is going to be a sideways shove on the crew. That's especially bad if that thrust level changes a lot (say, to randomize the ship's vector), or if thrust is high (so the crew couldn't stand up while the ship was thrusting).
Note that on Earth, "naval ship orientation" is really the same as "skyscraper orientation". Both are aligned so that the decks / floors are perpendicular to the predominant direction of gravity ("down"). If you have high thrust that's often used, then the predominant direction is the direction of thrust. So it only makes sense to align the ship to take that into account, even if you have artificial gravity as a supplement. If the ship uses thrust only briefly and spends most of its time coasting, like a modern-day space probe, or has very low thrust, then you might ignore that direction as irrelevant during the mission. Naval ships are narrow compared to their length for hydrodynamic reasons -- less drag on the hull makes for a faster ship, though they have to keep some width for stability. Skyscraper are tall compared to their width because land in downtown cities is scarce and expensive and bought by area, not volume. (Also ego...) Neither of those factors are relevant in space. You might want a long, pointy ship just for the sake of tradition, but that's not really dictated by the environment. The fact that you have to travel more against gravity in a skyscraper (hence elevators), while you can walk horizontally over more of a ship, is a practical advantage for the ship layout, but it's not a dominant factor. (Besides, elevators are just another fun thing to break, right?) A sphere gives you the most volume for the area of the hull, and minimizes the travel distance between points inside the ship. (Not that travel is normally random; the architects will no doubt take into account where people have to get to in their jobs when choosing a layout.) Spheres also minimize the moment of inertia, so they can likely more easily change direction than a long, thin object. You don't have to have spherical ships, but other shapes will have a reason for their existence. |
10-19-2019, 10:54 AM | #7 | |
Join Date: Aug 2007
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Re: Spaceship Weapons and Gravity Layout
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Maneuvering in space battles is grossly overrated. Speed needs to be very high relative to weapon's range for it to be much use at all. Your artifical gravity system is confusing to say the least. However, unless it completely negates acceleration forces "naval" orientation just isn't an option.
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Fred Brackin |
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10-19-2019, 07:01 PM | #8 | ||||||||||
Hero of Democracy
Join Date: Mar 2012
Location: far from the ocean
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Re: Spaceship Weapons and Gravity Layout
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Come to think of it, ideally you want to point a small surface towards your target and then have your main thrust come orthogonal to that. I'm not sure how that effects the structural stress on the craft. It also gets weird if you want to close with your target. Quote:
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Lining up gravity and thrust is probably the best thing to do, I'm just trying to look at other knock-on effects. Quote:
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10-19-2019, 07:38 PM | #9 | |
Join Date: Aug 2007
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Re: Spaceship Weapons and Gravity Layout
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If you are going to maneuver this is exactly where naval orientation does not work. A crew can not operate with 1 G towards their feet and even 0.1 Gs behind or to the side of them. You could perhaps strap everyone in and turn off the artifical gravity but you'd still have problems for anyone not strapped in like damage control parties. Naval orinetation requires virtually all of any accelration forces to be completely neutralized which is how things work in Star Wars and Star Trek. If you're not doing that you'll only see "naval" orientation in immobile space stations.
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Fred Brackin |
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10-20-2019, 01:05 AM | #10 | |
Join Date: Feb 2007
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Re: Spaceship Weapons and Gravity Layout
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One exception: does your ship ever enter atmospheres, land, or otherwise operate very near planetary surfaces? If so, the 'wet navy' arrangement can make landing and near-surface operations more convenient.
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