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Post by Rocket Witch on Oct 29, 2017 3:42:03 GMT
ADDIT: Ah! more efficient! Nuclear thermal rocket. Interesting. So what is the actual status of this technology? Is it viable for cheaper surface to orbit costs too? A number were built and test-fired mainly in the 70s. Examples include NERVA, KIWI-B4, and RD-0410. My favourite is LANTR, which can inject oxidiser into the exhaust stream for a massive boost in thrust on-demand. They're a fully mature technology, but the general public's fear of nuclear things and concerns arising from what would happen if an NTR failed mid-flight (ie. radioactive dust going everywhere if it exploded) have precluded them from actual use to date. They aren't cheap at all, and their thrust/weight ratio is relatively bad. I've heard miniturisation of reactors has improved a lot since the days of NERVA, but I haven't seen any real NTR design that looks like the ones we have in CDE myself. wtf are you gonna use Iron or Titanium for when Steel (any type) and Beta Titanium are superior? U-235? Plutonium in general? RCC? Boron? Gadolinium? UHMWPE? etc. Hehe. You know, you gave me the idea of making a tier chart with all the materials. Anyway, yeah, there is just one pick for a given thing depending on what you want —a set of things each for mass, cost, and size optimisationin a given module— and some things just don't get picked. I don't like to be game-optimal myself though; it's in the spirit of the simulation to bear in mind what would work better in reality than ingame. Mc stands for megacredit, million credits. Small thing, but Q said once that the c doesn't actually stand for anything, it's just used as a generic currency symbol.
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Post by RiftandRend on Oct 29, 2017 4:25:50 GMT
I would say the "Strider" experiment was a failure. Very high dV but very low acceleration is not an option for making a transit from Themis to Mars on a short time frame. I watched a couple Youtubes where guys were using the Methane and/or Hydrogen tankers and I was able to very closely match their trajectories using those craft. I was NOT able to match those trajectories using the Strider design I posted up above. Arrived much later and some manuevers just were not possible "Overwhelmed by gravity." I would guess that something in the 50 to 100 micro g is a minimum for a ships acceleration. What sort of acceleration did your ship have with only MPTDs?
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Post by dichebach on Oct 29, 2017 6:50:01 GMT
I would say the "Strider" experiment was a failure. Very high dV but very low acceleration is not an option for making a transit from Themis to Mars on a short time frame. I watched a couple Youtubes where guys were using the Methane and/or Hydrogen tankers and I was able to very closely match their trajectories using those craft. I was NOT able to match those trajectories using the Strider design I posted up above. Arrived much later and some manuevers just were not possible "Overwhelmed by gravity." I would guess that something in the 50 to 100 micro g is a minimum for a ships acceleration. What sort of acceleration did your ship have with only MPTDs? An order of magnitude below the typical range of 40 to 200 micro g. Not sure if that is nano g?
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Post by bigbombr on Oct 29, 2017 7:04:01 GMT
What sort of acceleration did your ship have with only MPTDs? An order of magnitude below the typical range of 40 to 200 micro g. Not sure if that is nano g? An acceleration of over 5 milligee should be easily achievable. 40 µgee would be 40 000 nanogee. If your acceleration is measured in µgee, it's way to low for comfortable maneuvering. If you want to try maneuverability, use the Jovian system (Jupiter and it's moons) in sandbox to test if your craft have sufficient delta-v and acceleration. If you have more than 12 km/s of delta-v and an acceleration of 50+ mgee, you'll (almost) never have trouble maneuvering. 6 km/s and 10 mgee are good minimum thresholds IMO.
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Post by dichebach on Oct 29, 2017 14:35:13 GMT
An order of magnitude below the typical range of 40 to 200 micro g. Not sure if that is nano g? An acceleration of over 5 milligee should be easily achievable. 40 µgee would be 40 000 nanogee. If your acceleration is measured in µgee, it's way to low for comfortable maneuvering. If you want to try maneuverability, use the Jovian system (Jupiter and it's moons) in sandbox to test if your craft have sufficient delta-v and acceleration. If you have more than 12 km/s of delta-v and an acceleration of 50+ mgee, you'll (almost) never have trouble maneuvering. 6 km/s and 10 mgee are good minimum thresholds IMO. Ah, I'm confusing micro and milli . . . most of the stock ships have accelerations in the ~40 to 350 milli g ballpark. A few have values that are expressed in micro g "µ g". Apparently a ship with acceleration that small is fine as long as it never has to maneuver near a large object, the Belt Trawler for example. Having found that my beefy "Hydro D" (Hydrogen Deuteride ships with various weapon loadout focused on a specific theme and with WAAYY too much cross-section resulting from two 1kt HD tanks, as well as ridiculous quantities of power, big lasers 8 Sniper Nuke launchers, that sort of thing. . .) designs fell like Goliath to the stock designs in the Main Belt Extraction engagement, I'm now experimenting with "Hydro Dm" line "Hydrogen Deuterid Mini" using only two 250 t tanks and a tiny reactor (105 kW). When they can hit you with one of the smaller rail guns at like 55km you know you are just too big . . . The armor choices are triggering my OCD and the lack of a convenient in-game spreadsheet to allow all the materials to be compared readily is artificially inflating my play time. Fun way to pick up a few tidbits of materials science though! Yep! However, the UI seems to be very effectively designed. Apparently all values change "on the fly" so deactivating a particular module is an easy to way to check the stats without it!
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Post by dichebach on Oct 29, 2017 15:04:58 GMT
So I tried your armor configuration (more or less) and I must say, it didn't seem to perform very well. Course that could be because my ships were as big as a barn. Having skimmed the materials list a bit more I do have a few questions for you, this may arc off into an intense discussion of armor, and perhaps there is a not too old thread around that would be better to take the discussion to? Oh, this thread looks interesting: childrenofadeadearth.boards.net/thread/201/capital-ship-armor-threadThe first questions that come to mind: (1) Why "tin" instead of "lead." Lead appears superior in every way for the apparent role the tin is intended to serve, no? Cheaper, denser, higher melting point, stretches better, etc.?? (2) half a meter of graphite aerogel? Wow that is actually pretty massive, rather bulky, fairly expensive and I'm not entirely clear what it is doing? Is this a "heat absorbing" layer or what? Which specs are the key for heat mitigation? (3) amorphous carbon, is this like the "fall back" line? assuming the outer layers are being swiss cheesed this is sort of a "general purpose dense, hard, strong and slow to melt" layer? When you say "thin" does that mean 500 micro meters? (4) What the heck does the silk do!? I can see myself getting obsessed with just the armor design "Spaceship-Armorer Simulator 2017" . . . How does one achieve the sloping that millesmissiles referred to (in the OP of the thread linked above) where his ships taper from a ~5m diameter bow to a ~20 m diameter stern? place a 4 m diameter space in the front and a 19m spacer in the back? Given the guns are generally positioned radially at various points along the ship cylinders, what does "broadside" actually mean? Does this mean the ship will turn at _whatever_ angle gives it line of sight with maximum number of guns? Or is it actually a fixed angle and therefore one wants to actually arrange one's weapons in stripes running down the long axis of the hull? Given the obvious importance of cross-section, it seems to me that angling the hull from narrow to wide going from stem to stern and then positioning the weapons so that effectively all of them can have line of sight while the craft is pointing its nose directly at the target is the wise design, but I'm not sure to what degree the game engine affords this? Does the game account for blocked line of sight from modules blocking one another and/or opened line of sight from the angle of the hull?
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Post by The Astronomer on Oct 29, 2017 15:14:29 GMT
A quick question: why would you even build a helium tanker? Helium is almost useless in CDE except for those who uses MPDs, maybe.
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Post by dichebach on Oct 29, 2017 15:17:45 GMT
A quick question: why would you even build a helium tanker? Helium is almost useless in CDE except for those who uses MPDs, maybe. I noticed that the stock MPD ships had very high dV, and didn't realize their low acceleration is a "trap." To get hapless spaceship engineer noobs like me stuck orbiting Sol in awkward orbits, unable to overwhelm gravity . . .
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Post by The Astronomer on Oct 29, 2017 15:27:31 GMT
A quick question: why would you even build a helium tanker? Helium is almost useless in CDE except for those who uses MPDs, maybe. I noticed that the stock MPD ships had very high dV, and didn't realize their low acceleration is a "trap." To get hapless spaceship engineer noobs like me stuck orbiting Sol in awkward orbits, unable to overwhelm gravity . . . If you're bad at low acceleration maneuver like me, consider strapping Chandra into a seat on a large methane tanker or whatever tanker you designed.
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Post by dichebach on Oct 29, 2017 15:46:53 GMT
I noticed that the stock MPD ships had very high dV, and didn't realize their low acceleration is a "trap." To get hapless spaceship engineer noobs like me stuck orbiting Sol in awkward orbits, unable to overwhelm gravity . . . If you're bad at low acceleration maneuver like me, consider strapping Chandra into a seat on a large methane tanker or whatever tanker you designed. Yeah, I got her there using the Methane tanker I believe! The tradeoffs in these spaceship designs are fascinating Ah here we go, now we can get down to some SERIOUS spreadsheetsturbation childrenofadeadearth.boards.net/thread/143/materials-spreadsheet?page=2&scrollTo=3256I wonder if the devs version is better? Haven't used the command console yet.
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Post by dichebach on Oct 29, 2017 16:07:27 GMT
So if I wanted to create a dummy variable in that spreadsheet with three values 1 (for conductors), 0 (for 'neutrals' or missing values), or -1 (for insulators) what thresholds would I want to use for the cutoffs between conductor/neutral and neutral/insulator? I see copper has a Thermal conductivity of 400 W/(m K) whereas . . . fiberglass is like www.engineeringtoolbox.com/thermal-conductivity-d_429.html 0.04 According to pokington's spreadsheet, Aramid fiber is at 0.04, Polytetrafluoroethylene is at 0.25 and heavy water at 0.595. Obviously everything at 0.04 and below can be considered an insulator, but should materials with somewhat higher thermal conductivity also count as insulators? And what is the lowest value that should count as a "conductor? I'm thinking that layering of very thin alternating layers of conductors/insulators might be an effective laser/nuke flash defense, depending on how the layers are arranged? I would assume Conductor on outside, then insulator, then conductor?
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Post by bigbombr on Oct 29, 2017 16:31:31 GMT
... Having found that my beefy "Hydro D" (Hydrogen Deuteride ships with various weapon loadout focused on a specific theme and with WAAYY too much cross-section resulting from two 1kt HD tanks, as well as ridiculous quantities of power, big lasers 8 Sniper Nuke launchers, that sort of thing. . .) designs fell like Goliath to the stock designs in the Main Belt Extraction engagement, I'm now experimenting with "Hydro Dm" line "Hydrogen Deuterid Mini" using only two 250 t tanks and a tiny reactor (105 kW). When they can hit you with one of the smaller rail guns at like 55km you know you are just too big . . . ... I personally recommend using methane in a NTR/MPDT dual setup. Methane is denser than hydrogen deuteride, while having an exhaust velocity close to hydrogen deuteride in NTR's. If you're leaning more to MPDT's, heavy water is also worth considering in a dual setup if you plan to mostly use the MPDT. If you're going pure MPDT, neon is cheap, dense and a decent performer. When in a doubt, use heavy laserdrones. They eat most things for breakfast.
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Post by AdmiralObvious on Oct 29, 2017 19:53:38 GMT
So I tried your armor configuration (more or less) and I must say, it didn't seem to perform very well. Course that could be because my ships were as big as a barn. Having skimmed the materials list a bit more I do have a few questions for you, this may arc off into an intense discussion of armor, and perhaps there is a not too old thread around that would be better to take the discussion to? Oh, this thread looks interesting: childrenofadeadearth.boards.net/thread/201/capital-ship-armor-threadThe first questions that come to mind: (1) Why "tin" instead of "lead." Lead appears superior in every way for the apparent role the tin is intended to serve, no? Cheaper, denser, higher melting point, stretches better, etc.?? (2) half a meter of graphite aerogel? Wow that is actually pretty massive, rather bulky, fairly expensive and I'm not entirely clear what it is doing? Is this a "heat absorbing" layer or what? Which specs are the key for heat mitigation? (3) amorphous carbon, is this like the "fall back" line? assuming the outer layers are being swiss cheesed this is sort of a "general purpose dense, hard, strong and slow to melt" layer? When you say "thin" does that mean 500 micro meters? (4) What the heck does the silk do!? I can see myself getting obsessed with just the armor design "Spaceship-Armorer Simulator 2017" . . . It's been some time since I played, however, tin has very comparable properties to lead, and tends to not fragment as much as tin seems to do. I personally prefer lead as a whipple as well. However, I don't remember which had the higher "speed of sound", basically the one which is lower tends to turn liquid at the speed noted, which is usually bad for armor, especially once the liquid resolidifies. The graphigel basically serves as air, which more or less will reduce the impact of anything passing through it, especially if the shot in question is stupidly small. Think of it as an atmosphere, considering how fast the incoming shot is going. Amorphous Carbon is a good general purpose buffer, especially for its cost and weight. It tends to stop most things hitting it, and it doesn't fragment/spall much that I'm aware of. Spider silk is spider silk (I believe, it might be manufactured silk, not sure), it's incredibly good at catching any spall which does happen to escape, assuming you have enough space behind it for the silk to stretch.
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Post by Rocket Witch on Oct 29, 2017 20:14:42 GMT
So I tried your armor configuration (more or less) and I must say, it didn't seem to perform very well. Course that could be because my ships were as big as a barn. Having skimmed the materials list a bit more I do have a few questions for you, this may arc off into an intense discussion of armor, and perhaps there is a not too old thread around that would be better to take the discussion to? Oh, this thread looks interesting: childrenofadeadearth.boards.net/thread/201/capital-ship-armor-threadThe first questions that come to mind: (1) Why "tin" instead of "lead." Lead appears superior in every way for the apparent role the tin is intended to serve, no? Cheaper, denser, higher melting point, stretches better, etc.?? (2) half a meter of graphite aerogel? Wow that is actually pretty massive, rather bulky, fairly expensive and I'm not entirely clear what it is doing? Is this a "heat absorbing" layer or what? Which specs are the key for heat mitigation? (3) amorphous carbon, is this like the "fall back" line? assuming the outer layers are being swiss cheesed this is sort of a "general purpose dense, hard, strong and slow to melt" layer? When you say "thin" does that mean 500 micro meters? (4) What the heck does the silk do!? I can see myself getting obsessed with just the armor design "Spaceship-Armorer Simulator 2017" . . . How does one achieve the sloping that millesmissiles referred to (in the OP of the thread linked above) where his ships taper from a ~5m diameter bow to a ~20 m diameter stern? place a 4 m diameter space in the front and a 19m spacer in the back? Given the guns are generally positioned radially at various points along the ship cylinders, what does "broadside" actually mean? Does this mean the ship will turn at _whatever_ angle gives it line of sight with maximum number of guns? Or is it actually a fixed angle and therefore one wants to actually arrange one's weapons in stripes running down the long axis of the hull? Given the obvious importance of cross-section, it seems to me that angling the hull from narrow to wide going from stem to stern and then positioning the weapons so that effectively all of them can have line of sight while the craft is pointing its nose directly at the target is the wise design, but I'm not sure to what degree the game engine affords this? Does the game account for blocked line of sight from modules blocking one another and/or opened line of sight from the angle of the hull? (1) Lead has no appreciable tensile strength to hold the bulk of an armour sheet together, while the highly negative Poisson's ratio may exacerbate this*. When a projectile hits an armour plate there is compression at the site of impact, with a shearing force immediately around the edges thereof, while the rest of the material is stretched toward the impact as the material is strained. It seems you need a couple hundred MPa to withstand these shocks. *I just realised this seems to be bugged by lead having the wrong moduli. Here is a fix: childrenofadeadearth.boards.net/thread/1843(2) It's not massive; this aerogel is an incredibly light material; even lithium is over 60 times more dense than it. While the cost is quite high per kilogram, you're not actually using much of it compared to conventional armour layers (contrast with nickel-phosphorus microlattice, which is so amazingly expensive even its low density doesn't help). It is quite bulky indeed, but doesn't make the ship any larger than if it had a space-filled whipple shield instead. It is a decent buffer against heat ablation due to its sheer bulk and the high conductivity spreading that heat very well, and with an outer bumper like tin to plasmify projecitles it will absorb kinetics as well. (3) Amorphous carbon isn't dense, but yes, it kind of does everything so if you can only have one armour layer (as on turrets) this is fairly a popular pick. Personally I have more faith in boron carbide. (4) Silk is very elastic, allowing it to absorb impacts very well. It's not a particularly strong fibre compared to synthetic examples but by far one of the cheapest and very light too. I like to use it as the innermost layer for spall lining, but I'm unsure how effective it actually is. Either spacers or various sizes and shapes of propellant tanks can achive this effect. Broadside is actually an 'orient weapons toward enemy' command. A ship with a fixed frontal weapon will attempt to align its nose with the target vector. A ship with turrets both on the nose and sides will orient itself at a 45 degree angle, particularly if they are not the extruded kind. The game does not check for weapon line of sight. Ships can shoot through any part of themselves without harm. If you want to try out some extreme cheese you can make a ship with a bulge in the middle or front (like the Hiveship), then place turrets behind that so they are covered by sloped armour which they can shoot through. For realism I like to arrange guns in a spiral pattern: steamcommunity.com/sharedfiles/filedetails/?id=1183860486So if I wanted to create a dummy variable in that spreadsheet with three values 1 (for conductors), 0 (for 'neutrals' or missing values), or -1 (for insulators) what thresholds would I want to use for the cutoffs between conductor/neutral and neutral/insulator? I see copper has a Thermal conductivity of 400 W/(m K) whereas . . . fiberglass is like www.engineeringtoolbox.com/thermal-conductivity-d_429.html 0.04 According to pokington 's spreadsheet, Aramid fiber is at 0.04, Polytetrafluoroethylene is at 0.25 and heavy water at 0.595. Obviously everything at 0.04 and below can be considered an insulator, but should materials with somewhat higher thermal conductivity also count as insulators? And what is the lowest value that should count as a "conductor? I'm thinking that layering of very thin alternating layers of conductors/insulators might be an effective laser/nuke flash defense, depending on how the layers are arranged? I would assume Conductor on outside, then insulator, then conductor? Insulator outside, conductor behind. The conductor seems to suck heat through the insulator and keep it cool. You can also try something reflective (aluminium, magnesium, silver) with a conductor behind that; this will, or appears to, reflect most of the laser energy while the conductor keeps the reflector from melting. But yes, the conductor-insulator sandwich, usually employing diamond (conductivity 2100 W/m K) and PTFE or rubber, is very effective. Multiple thin layers of insulators with space between also works better than the sum of its mass & cost. These effects are most likely due to the lacklustre laser damage model, really, which is only effective at modelling low energy lasers. David made a laser armour spreadsheet here: childrenofadeadearth.boards.net/thread/1390
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Post by dichebach on Oct 29, 2017 22:52:31 GMT
Fascinating stuff! Thanks for all the detailed replies folks.
So the aerogel: is it more effective than simply a vaccuum space? I would assume so, which then raises the question of "what characteristics are the guide to what is the best material for this role?" Obviously the very low mass per volume. High thermal conductivity?
I know that they use spacing in contemporary tank armor (and probably other military applications too) so the idea that using space between layers has a lot of appeal. It is just such an esoteric topic, hard to guess what will work well. I suppose having a 5cm layer of a very light material like the aerogel between every layer (except the conductor insulator sandwich which obviously needs to be in contact) is a good general rule of thumb?
What about fiberglass insulation, or just plain old air!? I suppose keeping the layer pressurized to retain the air would be even more troublesome that just spraying the aerogel in there and letting it cure . . .
I noticed that remarkable thermal conductivity of diamond and it piqued by interest! Given how dense it is, it would seem to be a pretty good outer layer for kinetics too? Pricey I bet . . .
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