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Post by jonen on Nov 6, 2016 6:04:52 GMT
If you do enough damage to a crew module to pierce the armor, it pops. It's dead. It's gone.
Modeling the insides of the modules to calculate the exact effects of every impact would not really be feasible, and a sufficient number of sufficiently big holes means that anyone in that pressure vessel isn't going to be contributing much of anything useful to the engagement anyway.
So from a gameplay standpoint, it probably makes sense, but how realistic is it?
One atmosphere of pressure shouldn't be enough to make it pop like a balloon just because you poke a hole in it, right?
Realistically, shouldn't a lot of the high velocity kinetics - assuming they've not caused spalling, or shrapnel bouncing around inside the armor layer, and no explosives or anything - be going just about fast enough to punch clean through without shedding too much velocity or dumping too much energy into the crew module (well, depending on what's in their trajectory)? Small hole in, slightly messier hole in any intervening object or crew and messiest hole out. Worse if there's spalling from the armor layer. Worst if it starts bouncing around the insides of the module. And I figure the way to simulate multiple pressurized compartments is by using multiple crew modules (and eat the extra WW and AC technicians - not literally, even as emergency rations), so if there's too many or too big holes to patch in a module, and probably not enough spacesuits to go around, a penetrated crew compartment is at the very least mission killed.
But I'm not really a hard physics numbers guy - thoughts?
/This thread brought to you by: Insomnia, all those snips from Atomic Rockets with small holes being punched in crew compartments, that one scene in the Expanse, and a bunch of others.
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Post by nerd1000 on Nov 6, 2016 10:36:43 GMT
If you do enough damage to a crew module to pierce the armor, it pops. It's dead. It's gone. Modeling the insides of the modules to calculate the exact effects of every impact would not really be feasible, and a sufficient number of sufficiently big holes means that anyone in that pressure vessel isn't going to be contributing much of anything useful to the engagement anyway. So from a gameplay standpoint, it probably makes sense, but how realistic is it? One atmosphere of pressure shouldn't be enough to make it pop like a balloon just because you poke a hole in it, right? Realistically, shouldn't a lot of the high velocity kinetics - assuming they've not caused spalling, or shrapnel bouncing around inside the armor layer, and no explosives or anything - be going just about fast enough to punch clean through without shedding too much velocity or dumping too much energy into the crew module (well, depending on what's in their trajectory)? Small hole in, slightly messier hole in any intervening object or crew and messiest hole out. Worse if there's spalling from the armor layer. Worst if it starts bouncing around the insides of the module. And I figure the way to simulate multiple pressurized compartments is by using multiple crew modules (and eat the extra WW and AC technicians - not literally, even as emergency rations), so if there's too many or too big holes to patch in a module, and probably not enough spacesuits to go around, a penetrated crew compartment is at the very least mission killed. But I'm not really a hard physics numbers guy - thoughts? /This thread brought to you by: Insomnia, all those snips from Atomic Rockets with small holes being punched in crew compartments, that one scene in the Expanse, and a bunch of others. Here's another thing: Why wouldn't the crew (knowing that they're going into combat) put on space suits so that they can survive any depressurization event and (potentially) even keep fighting?
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Post by cuddlefish on Nov 6, 2016 10:54:19 GMT
I suspect that many, though not all, hull materials are such that the interior space after they are pierced would be rather inhospitable - spalling and related shock damage, radiated heat from molten hot segments, and so on. The odds of such a compartment being able to keep fighting meaningfully, both in terms of the crew being able to fight and (critcally) the control linkages to the various ship systems being in working order, seem remote whether or not there's actual killing of the crew involved.
That being said, agree with you that low profile mechanical counter-pressure suits and SCBA gear seem mandatory even for comparatively minor damage - beyond the risk of depressurization, IIRC the figure on airliner cabin fires is that if you're not out within 60-90 seconds, the fume exposure is either fatal or sufficiently incapacitating as to make escape impossible. So even if you kept atmosphere through the damage, there's plenty odds you might be wishing you hadn't.
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Post by goduranus on Nov 6, 2016 10:57:19 GMT
You can simulate crew robustness by adding a few remote control modules, the ship will probably keep on fightig no matter what.
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Post by nerd1000 on Nov 6, 2016 12:16:58 GMT
I suspect that many, though not all, hull materials are such that the interior space after they are pierced would be rather inhospitable - spalling and related shock damage, radiated heat from molten hot segments, and so on. The odds of such a compartment being able to keep fighting meaningfully, both in terms of the crew being able to fight and (critcally) the control linkages to the various ship systems being in working order, seem remote whether or not there's actual killing of the crew involved. That being said, agree with you that low profile mechanical counter-pressure suits and SCBA gear seem mandatory even for comparatively minor damage - beyond the risk of depressurization, IIRC the figure on airliner cabin fires is that if you're not out within 60-90 seconds, the fume exposure is either fatal or sufficiently incapacitating as to make escape impossible. So even if you kept atmosphere through the damage, there's plenty odds you might be wishing you hadn't. True to some degree. On the other hand, the rounds we fire at enemy ships are usually tiny little hypervelocity pellets, so the amount of spalled material is likely to be pretty small. The best point of reference is probably the effects of HEAT warheads (which achieve similar impact velocities to our railguns) on armoured fighting vehicles- a tank is a very confined space, yet when a tank is knocked out the crew usually survives unless the ammo explodes or they were directly in the path of the incoming projectile. Our crew modules contain no explodey bits and generally have much thinner plating than a tank while also having much larger volume for the crew to be spread out in, so I think most command modules could be penetrated many times without all the crew being killed. No debating the fact that pumping 500 bullets into a crew module will take it out, but sometimes our modules are disabled by a single round that's lucky enough to get through the armour when all other hits were successfully deflected. Control links to the rest of the ship are actually pretty easy to protect- they're going to be electrical wiring or fibre optics, which are small (thus unlikely to be hit) and easy to armour or provide extra redundancy. Any computers that rely on the command module atmosphere for cooling will overheat, though running a liquid cooling loop probably makes a lot of sense for them anyway (Ensign Bob's PlayStation on the other hand is toast). The module can also have internal subdivisions that block fragments and heat effects while also allowing you to seal off breached sections, so even assuming the module gets hit by one of the stock 286mm coilgun's 10 kilo dinner plates at 5 km/s it might be able to retain partial functionality (Bob and the rest of his section, however... well they won't be needing their PlayStation any more).
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Post by oprean on Nov 6, 2016 15:23:01 GMT
On this matter I think a compromise would be in order, I do agree that the current system is not perfect, and that a more advanced simulation on what happens inside a crew compartment would just add complexity where it's not needed, let's make one thing clear, I don't think the crew has space suits, they are traveling as light as possible, just as submarine crews don't have diving gear, they just hope they won't have to experience outside during their service times. So, if a crew compartment is punctured by a 1 gram projectile, are all 250 people in a 15290 m^3 tube going to cease to exist instantly? No, first all the air has to pass through that hole from 1 atm with the pressure decreasing, but that would take infinity time to reach total vacuum, so let's say the pressure has to drop to where a human looses consciousness, but the people will try to plug that hole, just put a plunger over it or something, so if the repair time is more than the time the pressure has to lower to where everyone looses consciousness the crew module shouldn't be destroyed, I mean, the math should be done as simple as possible, but I'd love to see something like this in game.
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Post by wafflestoo on Nov 6, 2016 15:29:24 GMT
I think it's in the canon material that crews are in compression suits, and I don't think it's mentioned but I doubt they have the crew cans fully pressurized. I think the ISS runs 1/2 atm or less. But still... imagine this flying through your crew module: Attachment Deleted
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Post by oprean on Nov 6, 2016 17:32:08 GMT
When you make a new crew compartment it sais the skin must be strong enough to withstand 1 atm of internal pressure, I just assumed they are at that pressure.
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Post by wafflestoo on Nov 6, 2016 18:27:26 GMT
Huh, well maybe we're operating from different assumptions then.
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Post by jonen on Nov 6, 2016 19:32:47 GMT
I figure some sort of lightweight compression suit they put on whenever they're coming up on an intercept. Nothing that'll hold up to full vacuum for long but will handle drops in pressure, and has a mask and a supply of breathable mix for if the compartment fogs up with toxic fumes. If the ship has EVA techs, probably only them and maybe the DC crew in anything like full space suits during combat. Realistic response to catastrophic damage to the pressure vessel with full loss of pressure is probably some kind of inflatable individual life-support ball - stay in the ship, hope you survive until the bombardment ends, hope one of the spacesuited DC techs survived to help you manhandle your pod out of wherever it's wedged into a an emergency rescue or reentry vehicle if possible/necessary, or to conduct enough repairs to maybe make the crew module marginally habitable while you wait for rescue. That'll probably not come in time, but 'ey - maybe you were part of a fleet, and your team won, and some of your surviving task force may be tasked with personnel recovery.
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Post by jaberwo on Nov 6, 2016 21:21:39 GMT
If your mass budget allows for emergency reentry vehicles, then space suits shludn't be a problem, should they? Life support balls seem very plausible though. In general, I would not want to be on one of those ships. The crew survival rates seem to be atrociously low. By the way, the ISS is on full sea level pressure: en.wikipedia.org/wiki/ISS_ECLSS (Could not verify the sources though) Is there any mention of how humans have (been) adapted to microgravity and exposure to radiation?
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Post by RA2lover on Nov 6, 2016 21:51:39 GMT
Here's another thing: Why wouldn't the crew (knowing that they're going into combat) put on space suits so that they can survive any depressurization event and (potentially) even keep fighting? The same reason submarine crews don't work while on diving suits: they're too cumbersome to use while keeping combat effectiveness.
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Post by jonen on Nov 6, 2016 21:52:23 GMT
If your mass budget allows for emergency reentry vehicles, then space suits shludn't be a problem, should they? Life support balls seem very plausible though. In general, I would not want to be on one of those ships. The crew survival rates seem to be atrociously low. By the way, the ISS is on full sea level pressure: en.wikipedia.org/wiki/ISS_ECLSS (Could not verify the sources though) Is there any mention of how humans have (been) adapted to microgravity and exposure to radiation? This kind of re-entry vehicle. (Emergency Re-Entry Capsule, Inflatable.) Reminder - the only two places with atmosphere you may want to do an emergency landing on rather than try to remain in orbit are Mars and Titan.
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Post by jaberwo on Nov 6, 2016 22:25:27 GMT
This kind of re-entry vehicle. (Emergency Re-Entry Capsule, Inflatable.) Reminder - the only two places with atmosphere you may want to do an emergency landing on rather than try to remain in orbit are Mars and Titan. That's pretty cool and seems lighter than what I was imagining. Still, not sure if it would be prevalent in the setting.
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Post by wafflestoo on Nov 7, 2016 4:54:53 GMT
Here's another thing: Why wouldn't the crew (knowing that they're going into combat) put on space suits so that they can survive any depressurization event and (potentially) even keep fighting? The same reason submarine crews don't work while on diving suits: they're too cumbersome to use while keeping combat effectiveness. True, but compression suits aren't so bad. My assumption is that hypersonic shock and the resulting firestorm are probably going to accomplish what decompression probably isn't.
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