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Post by Apotheon on Sept 7, 2018 18:56:01 GMT
Hey! As you may know I'm creating civilian spaceships which are aggressively minimised for special objectives. However, I also want my ships to be reasonably realistic. As an example, I've created a spacecraft, which works in CDE and I want to know why it wouldn't work in reality!
Here's the example spacecraft: (Edit: please tell me how to create spoiler tags here)
Inside, it's just a stack of an Apophys propulsion, Apophys power, and two stacks of propellant tanks with a command module in the middle.
My questions: - How realistic is CDE propulsion/power? I assume it's possible to re-create real propulsion or power and get accurate results within an order of magnitude, at least within reason, or is it coarse?
- How realistic is Apophys propulsion/power? The stuff is highly optimised and that makes me wonder if it's because he's getting his information straight out of rocket books or just abusing the code?
- How realistic are command modules? The dimensions are kind of arbitrary and the volume apparently comes straight out of NASA research (I've read it), which leaves me only wondering about the mass.
- Also, for command modules, I'm making mine out of polyethylene... sounds awesome... and it's freaking plastic. Can someone reassure me that this doesn't wear out or degrade in any way on the inside or outside from air, vacuum, cosmic and solar radiation, the acids on human skin, or anything such? Apparently, NASA already use some kind of "reinforced polyethylene", is this what we have?
- My propellant tanks are made out of vanadium chromium steel. I've not idea what it's used for IRL, but it's steel and I guess it does what it says on the box?
- My radiators are made out of lithium. Reasonable?
- As for armour, you can probably tell my ship only has a decorative graphite aerogel layer. AFAIK, the ISS has lots of different kinds of aluminium armour and to create something that can stand micrometeorites, I should probably copy that?
- Finally, I'm certain a lot of stuff is omitted in CDE, for instance someone has suggested all ships should be heavier because of life support and if anyone can give me any information about this, I'd appreciate it a lot. For instance, would adding 1 ton of cargo, representing life support systems or the weight of anything that's not simulated, make it more realistic?
Obviously, it's not possible to create fully realistic spaceships here and my objective is only to create what's realistic within the scope of CDE. In other words, I want to create modules that are as realistic as possible within reason in terms of the statistics CDE inputs and outputs and spaceships that at least give me a reasonably realistic idea of the mass of a spacecraft with a given payload and propulsion system... for instance, imagine a spacecraft for transporting a 1,000 ton payload to the Mars quickly with nuclear thermal rockets... what would it mass? Can we get a reasonably accurate mass at all and what other statistics may we reasonably estimate with the help of CDE, a reasonable spacecraft, reasonable modules, and maybe a few corrections?
At least, with the above spacecraft, any one of you could probably point out that "hey, that armour isn't going to protect against micrometeorites"! Can we fix it at least to the point where one cannot immediately point out problems?
Again, I want to stress the fact that all simulations have limits and that what makes them simulations. Yes, CDE spaceships haven't got any hatches, but adding a hatch probably wouldn't change any of the statistics shown above any more than adding a 10 kg cargo module would, which changes nothing... in other words, if it doesn't affect the input or output, it's irrelevant.
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Post by Kerr on Sept 7, 2018 19:15:59 GMT
Hey! As you may know I'm creating civilian spaceships which are aggressively minimised for special objectives. However, I also want my ships to be reasonably realistic. As an example, I've created a spacecraft, which works in CDE and I want to know why it wouldn't work in reality!
Here's the example spacecraft: 
(Edit: please tell me how to create spoiler tags here)
Inside, it's just a stack of an Apophys propulsion, Apophys power, and two stacks of propellant tanks with a command module in the middle.
My questions: - How realistic is CDE propulsion/power? I assume it's possible to re-create real propulsion or power and get accurate results within an order of magnitude, at least within reason, or is it coarse?
- How realistic is Apophys propulsion/power? The stuff is highly optimised and that makes me wonder if it's because he's getting his information straight out of rocket books or just abusing the code?
- How realistic are command modules? The dimensions are kind of arbitrary and the volume apparently comes straight out of NASA research (I've read it), which leaves me only wondering about the mass.
- Also, for command modules, I'm making mine out of polyethylene... sounds awesome... and it's freaking plastic. Can someone reassure me that this doesn't wear out or degrade in any way on the inside or outside from air, vacuum, cosmic and solar radiation, the acids on human skin, or anything such? Apparently, NASA already use some kind of "reinforced polyethylene", is this what we have?
- My propellant tanks are made out of vanadium chromium steel. I've not idea what it's used for IRL, but it's steel and I guess it does what it says on the box?
- My radiators are made out of lithium. Reasonable?
- As for armour, you can probably tell my ship only has a decorative graphite aerogel layer. AFAIK, the ISS has lots of different kinds of aluminium armour and to create something that can stand micrometeorites, I should probably copy that?
- Finally, I'm certain a lot of stuff is omitted in CDE, for instance someone has suggested all ships should be heavier because of life support and if anyone can give me any information about this, I'd appreciate it a lot. For instance, would adding 1 ton of cargo, representing life support systems or the weight of anything that's not simulated, make it more realistic?
Obviously, it's not possible to create fully realistic spaceships here and my objective is only to create what's realistic within the scope of CDE. In other words, I want to create modules that are as realistic as possible within reason in terms of the statistics CDE inputs and outputs and spaceships that at least give me a reasonably realistic idea of the mass of a spacecraft with a given payload and propulsion system... for instance, imagine a spacecraft for transporting a 1,000 ton payload to the Mars quickly with nuclear thermal rockets... what would it mass? Can we get a reasonably accurate mass at all and what other statistics may we reasonably estimate with the help of CDE, a reasonable spacecraft, reasonable modules, and maybe a few corrections?
At least, with the above spacecraft, any one of you could probably point out that "hey, that armour isn't going to protect against micrometeorites"! Can we fix it at least to the point where one cannot immediately point out problems?
Again, I want to stress the fact that all simulations have limits and that what makes them simulations. Yes, CDE spaceships haven't got any hatches, but adding a hatch probably wouldn't change any of the statistics shown above any more than adding a 10 kg cargo module would, which changes nothing... in other words, if it doesn't affect the input or output, it's irrelevant.
1. Propulsion suffers from the baseline physical simulations for the materials involved, besides this its fine. 2. Total game-based min-maxing, intermediate physics knowledge is helpful to get a good sense of how thing A might influence property B. But good physics skill aren't required in any way. 3. Seems like a game-balancing thing to me rather than anything else, qswitched can change the mass arbitrary depending on several possible, but valid, assumptions. 4. The command module usually isn't exposed, but you could use some kinds of plastics to do such a thing. 5. Depends on the purpose, there isn't much speaking directly against it when talking about the game. 6. Why exactly? The ISS just uses a multitude of Whipple shields and spall liners, depending on whether or not the game actually realistically simulates the kinetics in the hypervelocity regime you want to go with crystalline materials such as sapphire. But you want civilian armor, so multiple layers of Whipple shield make sense. 7. That really depends on your assumption, realistic according to whom? Actual spacecraft? |
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Post by Apotheon on Sept 7, 2018 20:44:04 GMT
Hey! As you may know I'm creating civilian spaceships which are aggressively minimised for special objectives. However, I also want my ships to be reasonably realistic. As an example, I've created a spacecraft, which works in CDE and I want to know why it wouldn't work in reality!
Here's the example spacecraft:
(Edit: please tell me how to create spoiler tags here)
Inside, it's just a stack of an Apophys propulsion, Apophys power, and two stacks of propellant tanks with a command module in the middle.
My questions: - How realistic is CDE propulsion/power? I assume it's possible to re-create real propulsion or power and get accurate results within an order of magnitude, at least within reason, or is it coarse?
- How realistic is Apophys propulsion/power? The stuff is highly optimised and that makes me wonder if it's because he's getting his information straight out of rocket books or just abusing the code?
- How realistic are command modules? The dimensions are kind of arbitrary and the volume apparently comes straight out of NASA research (I've read it), which leaves me only wondering about the mass.
- Also, for command modules, I'm making mine out of polyethylene... sounds awesome... and it's freaking plastic. Can someone reassure me that this doesn't wear out or degrade in any way on the inside or outside from air, vacuum, cosmic and solar radiation, the acids on human skin, or anything such? Apparently, NASA already use some kind of "reinforced polyethylene", is this what we have?
- My propellant tanks are made out of vanadium chromium steel. I've not idea what it's used for IRL, but it's steel and I guess it does what it says on the box?
- My radiators are made out of lithium. Reasonable?
- As for armour, you can probably tell my ship only has a decorative graphite aerogel layer. AFAIK, the ISS has lots of different kinds of aluminium armour and to create something that can stand micrometeorites, I should probably copy that?
- Finally, I'm certain a lot of stuff is omitted in CDE, for instance someone has suggested all ships should be heavier because of life support and if anyone can give me any information about this, I'd appreciate it a lot. For instance, would adding 1 ton of cargo, representing life support systems or the weight of anything that's not simulated, make it more realistic?
Obviously, it's not possible to create fully realistic spaceships here and my objective is only to create what's realistic within the scope of CDE. In other words, I want to create modules that are as realistic as possible within reason in terms of the statistics CDE inputs and outputs and spaceships that at least give me a reasonably realistic idea of the mass of a spacecraft with a given payload and propulsion system... for instance, imagine a spacecraft for transporting a 1,000 ton payload to the Mars quickly with nuclear thermal rockets... what would it mass? Can we get a reasonably accurate mass at all and what other statistics may we reasonably estimate with the help of CDE, a reasonable spacecraft, reasonable modules, and maybe a few corrections?
At least, with the above spacecraft, any one of you could probably point out that "hey, that armour isn't going to protect against micrometeorites"! Can we fix it at least to the point where one cannot immediately point out problems?
Again, I want to stress the fact that all simulations have limits and that what makes them simulations. Yes, CDE spaceships haven't got any hatches, but adding a hatch probably wouldn't change any of the statistics shown above any more than adding a 10 kg cargo module would, which changes nothing... in other words, if it doesn't affect the input or output, it's irrelevant.
1. Propulsion suffers from the baseline physical simulations for the materials involved, besides this its fine. 2. Total game-based min-maxing, intermediate physics knowledge is helpful to get a good sense of how thing A might influence property B. But good physics skill aren't required in any way. 3. Seems like a game-balancing thing to me rather than anything else, qswitched can change the mass arbitrary depending on several possible, but valid, assumptions. 4. The command module usually isn't exposed, but you could use some kinds of plastics to do such a thing. 5. Depends on the purpose, there isn't much speaking directly against it when talking about the game. 6. Why exactly? The ISS just uses a multitude of Whipple shields and spall liners, depending on whether or not the game actually realistically simulates the kinetics in the hypervelocity regime you want to go with crystalline materials such as sapphire. But you want civilian armor, so multiple layers of Whipple shield make sense. 7. That really depends on your assumption, realistic according to whom? Actual spacecraft? Point 6, I want realistic civilian armour against micrometeorites because if not the crew might.. explode? In case my final paragraph confused my message, the final paragraph is only meant to address that everything cannot be simulated accurately, but I still want to create ships that are as realistic as CDE allows and above what CDE simulates, even if, for instance, micrometeorites aren't simulated. Point 7, realistic is realistic. I don't believe any deeper discussion of semantics is necessary here. Anyway, I just saw that CDE command module sizes actually don't match NASA, for whatever reasons! - A 26 crew module in CDE can only support 12 people according to NASA standards
- A 55 crew module in CDE can only support 26 people according to NASA standards
(NASA recommends 25 cubic meters per person, AFAIK) One situation where this makes a difference is if you're designing a passenger ship designed for, for instance, 100 passengers and you end up with less than 50% of NASA's recommended volume! In other cases, of course, such as that with the 26 crew ship, you can simply say "Oh well, I guess it only houses 12 people now and that's probably a more realistic crew size anyway", but regarding passengers, 100 is 100, if you know what I mean.
In other words, I can already suggest an improvement for my ship: increasing the command module to 55 in order to create NASA-standard volume. However, instead I will keep its size and remember that it's only really got 12 crew.
Anyone know how command module volume is calculated? Maybe qswitched knows something I don't know and the NASA recommendation doesn't scale linearly, for instance.
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Post by someusername6 on Sept 7, 2018 20:47:09 GMT
(Edit: please tell me how to create spoiler tags here) When posting, go directly to the BBCode tab, and surround anything you want on a spoiler tag with the tags "spoiler" and "/spoiler", surrounded by square brackets. Like this.  |
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Post by Apotheon on Sept 7, 2018 20:50:40 GMT
(Edit: please tell me how to create spoiler tags here) When posting, go directly to the BBCode tab, and surround anything you want on a spoiler tag with the tags "spoiler" and "/spoiler", surrounded by square brackets. Like this.
Right! It doesn't preview correctly, but it works. |
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Post by AdmiralObvious on Sept 8, 2018 0:45:51 GMT
On 5 and 6.
Lithium is a bit "wobbly" and reactive with a lot of different types of coolants you might consider using. High acceleration will end up bending, if not completely snapping it off, if it's just monolithic lithium of not very good thickness.
Whipple shields are the current norm for spacecraft. Partially because it's cheap, and works, partially because aerogel will probably end up shifting if it's not contained, again depending on the acceleration. Aerogel alone won't stop a micrometeor either, you're going to need something to shock the incoming rock to disperse it's energy.
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Post by Apotheon on Sept 8, 2018 1:57:24 GMT
On 5 and 6. Lithium is a bit "wobbly" and reactive with a lot of different types of coolants you might consider using. High acceleration will end up bending, if not completely snapping it off, if it's just monolithic lithium of not very good thickness. Whipple shields are the current norm for spacecraft. Partially because it's cheap, and works, partially because aerogel will probably end up shifting if it's not contained, again depending on the acceleration. Aerogel alone won't stop a micrometeor either, you're going to need something to shock the incoming rock to disperse it's energy. What's a realistic anti-micrometeorite only armour? In fact, what's a great way to model micrometeorite impacts? Googling, it appears NASA uses approximately 1 cm aluminium spheres going 7 km/s... I made a gun that shoots it and it ate through a 5 cm aluminium monolith immediately even though that's supposed to stop it according to NASA. If micrometeorites are a concern for interplanetary spaceships?
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Post by AtomHeartDragon on Sept 8, 2018 14:58:55 GMT
Lithium:
I generally consider anything from the first column of the periodic table and anything but beryllium and magnesium from the second column to be unsuitable for any structural applications as unalloyed metal. Even in space.
Tell an engineer that you want to encase air, humans or warm/hot cooling water in lithium or potassium and he will run away screaming and flailing his arms so fast that he won't actually be within earshot any more when you mention any actual coating you intend to use.
For some extra fun you can also tell him you intend to use it to pump liquid fluorine too (after he returns).
Aerogels:
Thick layers (so not your 500 micrometers visual flourish) might actually be reasonably effective against micrometeorites - think of them as bulk whipple shielding.
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Post by AtomHeartDragon on Sept 8, 2018 15:16:55 GMT
Googling, it appears NASA uses approximately 1 cm aluminium spheres going 7 km/s... I made a gun that shoots it and it ate through a 5 cm aluminium monolith immediately even though that's supposed to stop it according to NASA. - Was "immediately" on the first shot?
- Is your 1cm (diameter, not radius!) projectile the same mass as 1cm (diameter again) sphere?
- Was there any mention of inner side indentations to limit the spallation?
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Post by AdmiralObvious on Sept 8, 2018 17:19:21 GMT
On 5 and 6. Lithium is a bit "wobbly" and reactive with a lot of different types of coolants you might consider using. High acceleration will end up bending, if not completely snapping it off, if it's just monolithic lithium of not very good thickness. Whipple shields are the current norm for spacecraft. Partially because it's cheap, and works, partially because aerogel will probably end up shifting if it's not contained, again depending on the acceleration. Aerogel alone won't stop a micrometeor either, you're going to need something to shock the incoming rock to disperse it's energy. What's a realistic anti-micrometeorite only armour? In fact, what's a great way to model micrometeorite impacts? Googling, it appears NASA uses approximately 1 cm aluminium spheres going 7 km/s... I made a gun that shoots it and it ate through a 5 cm aluminium monolith immediately even though that's supposed to stop it according to NASA. If micrometeorites are a concern for interplanetary spaceships?
There are multiple realistic micrometeor armor types. Layers of aluminum sheets with a RCC lowest layer is one example. Another example would be a single aluminum sheet with Kevlar (para-aramid I think) in front of some sort of steel plate. I'd personally be testing this with a 60 km/s disk of 1cm carbon steel as the projectile, since there have been impacts of that speed with a similar density and hardness metal in actual (unmanned) space craft. You only need the projectile to hit once. If you live, you pass. If it penetrates internal components or spins the ship so hard it's going to kill the crew, you fail. |
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Post by AtomHeartDragon on Sept 8, 2018 18:26:22 GMT
What's a realistic anti-micrometeorite only armour? In fact, what's a great way to model micrometeorite impacts? Googling, it appears NASA uses approximately 1 cm aluminium spheres going 7 km/s... I made a gun that shoots it and it ate through a 5 cm aluminium monolith immediately even though that's supposed to stop it according to NASA. If micrometeorites are a concern for interplanetary spaceships?
There are multiple realistic micrometeor armor types. Layers of aluminum sheets with a RCC lowest layer is one example. Another example would be a single aluminum sheet with Kevlar (para-aramid I think) in front of some sort of steel plate. I'd personally be testing this with a 60 km/s disk of 1cm carbon steel as the projectile, since there have been impacts of that speed with a similar density and hardness metal in actual (unmanned) space craft. You only need the projectile to hit once. If you live, you pass. If it penetrates internal components or spins the ship so hard it's going to kill the crew, you fail. Translation: Put it in a sloooow rate of fire capacitor gun.
60km/s seems a bit excessive, though. Being hit by something like this automatically qualifies as freak accident - those *are* allowed to kill you.
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Post by Apotheon on Sept 8, 2018 20:18:41 GMT
Googling, it appears NASA uses approximately 1 cm aluminium spheres going 7 km/s... I made a gun that shoots it and it ate through a 5 cm aluminium monolith immediately even though that's supposed to stop it according to NASA. - Was "immediately" on the first shot?
- Is your 1cm (diameter, not radius!) projectile the same mass as 1cm (diameter again) sphere?
- Was there any mention of inner side indentations to limit the spallation?
Yeah, first shot or so, maybe the second. It's my first gun and I'm guessing it's all kinds of wrong.
By the way, according to a NASA powerpoint, the average micrometerorite speed is about 25 km/s, but it goes as high as 70 km/s. However, no information on average mass or density.
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Post by AdmiralObvious on Sept 8, 2018 20:57:41 GMT
- Was "immediately" on the first shot?
- Is your 1cm (diameter, not radius!) projectile the same mass as 1cm (diameter again) sphere?
- Was there any mention of inner side indentations to limit the spallation?
Yeah, first shot or so, maybe the second. It's my first gun and I'm guessing it's all kinds of wrong.
By the way, according to a NASA powerpoint, the average micrometerorite speed is about 25 km/s, but it goes as high as 70 km/s. However, no information on average mass or density.
Well, my example of 60 km/s was based on some tail debris of Halies comet hitting a satellite. It withstood a few impacts prior to that, until there was a piece the size, of I think a quarter impacting the ship. |
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Post by Lurker on Sept 8, 2018 21:50:47 GMT
60 km/s? could we have a link please?
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Post by AdmiralObvious on Sept 8, 2018 23:46:35 GMT
60 km/s? could we have a link please? It's some third hand information I heard about from one of Scott Manleys recent videos about someone drilling a hole into one of the space capsules. I'm unable to pull it up at the moment, but the comet trail event happened in '06 or '09. Sorry, I can't remember in the break room at work. Edit: It was the Giotto spacecraft. The particle that hit it was the size of a pea, not a quarter. |
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