tag:blogger.com,1999:blog-8150340806781551727.post5586621512095896548..comments2024-03-28T16:08:53.493+00:00Comments on ToughSF: Liquid Droplet Radiator Inter-ReflectionMatter Beamhttp://www.blogger.com/profile/16721504049578296529noreply@blogger.comBlogger67125tag:blogger.com,1999:blog-8150340806781551727.post-63557602647474471392021-11-14T06:12:30.942+00:002021-11-14T06:12:30.942+00:00what's percentage of droplets evaporate,lose a...what's percentage of droplets evaporate,lose and can't be collected,i mean,many droplets can't renter the radiator's recycle,they disappear foreverAnonymoushttps://www.blogger.com/profile/03284334548672427104noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-6815594828985504562017-09-29T14:35:42.317+01:002017-09-29T14:35:42.317+01:00If you are going to combine the string with the dr...If you are going to combine the string with the droplets anyway, there is really no reason to cycle the string. Simply suspend the string between the spray and collection points. No need for drive motors, nor fancy switching systems. The problem here, though, is that the strings now become an essentially dormant part of the structure. You are adding mass, and it now actually matters somewhat if the strings break.<br /><br />The benefits of the "string stage" coolant are:<br />*less coolant loss than droplet radiators (greater control over molecular vectors, and greater retention following stray impacts, as stray molecules in both cases will be pulled back into position through molecular bonds in string... or even by simply surface tension in contiguous string segments with broken molecular bonds)<br />*easier to configure threadsinto sheets with optimum molecular density (contiguous monofilament)<br />*less mass than wire or even spidersilk radiators (whether on loops or strands)<br />*superior performance to wire or spidersilk radiators (due to relaxed temperature limits)<br />*simplified operating principals <br />*less vulnerable to damage than wire or spidersilk radiators<br /><br />The only real downside is that it does not perform as well as droplet radiators, due to even relaxed temperature limitations. However, this is likely well compensated for, given that there is likely to be much less coolant loss (causing better mass reduction) and better control over optimal densities for best performance (it can be really difficult to get optimal densities in droplet flows, especially since droplets that are too closely packed could easily ick each other out of their vectors toward the collectors).Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-4755092968607610602017-09-28T15:36:11.860+01:002017-09-28T15:36:11.860+01:00I have an idea. Scale up the strings a bit and inc...I have an idea. Scale up the strings a bit and incorporate piezoelectric elements acting on microscopic surface elements. These surface elements can be actuated to switch between a superhydrophilic and superhydrophobic surface - I am not sure how, but tiny moving 'hairs' might be the solution. <br /><br />The string is in a superhydrophilic state when it picks up the liquid droplets. The droplets easy slide up its surface due to surface tension. They stick to the string as it is pulled along. At the collection point, an electric current it run through the string and the hairs rise, creating a hydrophobic surface. The droplets ball up and fall off, allowing them to be collected. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-32506386609210641102017-09-28T13:15:37.363+01:002017-09-28T13:15:37.363+01:00Working in reverse:
Thinking about it, actual sug...Working in reverse: <br />Thinking about it, actual sugar based variants probably would not work very well, unless you had a synthetic sugar with an extremely high melting point. Also, you are quite correct that viscous liquid strings could never offer the same temperature performance as droplets. However, there are other issues to consider. Most imprtantly would be coolant retention. Isolated droplets are extremely vulnerable to mass flow loss due to droplets that escape from the collection field. The liquid strings don't actually HAVE to hold up under temperature. It would be fine (and expected) for the strings to break. The benefit is that you would need less coolant mass because even the broken strings would be much easier to recover than free drifting droplets. Keep in mind that the strings will most likely break toward the point of highest temperature, which would be the source. Once they are sprayed, there will be no further tension on them to break them... until they reach the collector and are reeled in, at which point the temperature would be much lower, and the structural integrity much stronger. Any molecules that are not on course would be towed back toward the rest that are moving toward the collector.<br /><br />Yes, the sugar string concept is a variant of the liquid droplet concept. My notes on the spider thread concept were based first on the loop/belt radiator, assuming either a free-floating belt (except for the anchor point where the loop passes through the heat exchanger; note that this would require a circulation wheel running at sufficient speed that the inertia within the fibres is sufficient to encourage the sheets to flow to the maximum extent, rather than for the fibres to get bunched up --think about how you would through out the end of a blanket to have it drop flat on a bed), or having loops relying on the centrepetal force. Later, I incorpared the idea of free-floating strands that were not cycled through (extending out more like tapered antennae).<br /><br />I agree that the idea works better when grouped in bands or sheets. However, the strands in the bands do not need to be anchored (or tied) to one another.Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-27228968009467766272017-09-27T23:37:59.991+01:002017-09-27T23:37:59.991+01:00The wire radiator variant anchored only on one sid...The wire radiator variant anchored only on one side uses centripetal force from spinning loops to hold them in position. The wire variant I was describing is one where physical support structures pull along the wires and hold them under tension, like belts and pulleys. It would be much more robust against stresses and damage but the mass of the extra equipment suggests it works best when bunched together in 'bands'. <br /><br />Your idea sounds more like a conventional liquid droplet radiator where strings are used to move the droplets around, like a series of elevators. <br /><br />I seriously doubt that sugar-based or viscous liquids will hold up to the temperatures that radiators operate at, but I understand the analogy. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-22466843577249951822017-09-27T15:35:29.639+01:002017-09-27T15:35:29.639+01:00OTOH, the thin strands would be much more difficul...OTOH, the thin strands would be much more difficult to hit; and, the fact that they would only be anchored on one side, and would be extremely flexible, means that they would be morely likely to "give" under impact, rather than to break or tear. So this is probably a rather useful idea.<br />You probably don't need to drag the filaments through the radiator, either. If you allow the strands to "drip" ("stream" would probably be more accurate) out into a natural taper, thermal conductivity/emissivity should allow the waste heat to distribute itself down the line. The effect would be similar to demonstrations of wafers that melt and cut through butter simply by conducting the body heat of the person holding the wafer.<br /><br />Actually, this leads me to a variation of the liquid droplet radiators. One suitable example for this discussion is the cooking of sugars to the "string" stage. The result is a very thin strand of high viscosity liquid. So, use some kind of sugar molecule (or something similar) as the base of the coolant loop, and let it stream out into long threads that are MUCH easier to collect than individual droplets.Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-53034066597317766462017-09-26T16:28:27.635+01:002017-09-26T16:28:27.635+01:00Pretty vulnerable. The material is strong and flex...Pretty vulnerable. The material is strong and flexible but such thin strands are probably weaker than wet paper.<br /><br />The good thing though is that a liquid tank of spider silk can unspool the strands for months on end. 1 ton of silk 'goop' can be dried and wound into 976 million km of micrometer spider silk wire.Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-39636515455639057982017-09-26T04:42:02.324+01:002017-09-26T04:42:02.324+01:00Great suggestion!
How vulnerable are these spider...Great suggestion!<br /><br />How vulnerable are these spider silk radiators in combat though? If they are, could they be retracted and the bioship ends up spewing out super-heated water to cool down during battle instead?John Triptychhttps://www.amazon.com/John-Triptych/e/B016E003QUnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-88783797898581762942017-09-25T20:55:27.843+01:002017-09-25T20:55:27.843+01:00Congratulations!
I have a solution to your questi...Congratulations!<br /><br />I have a solution to your question, with the added bonus of fitting within the 'gene tech' theme: spider silk radiators.<br /><br />This is a variant on the wire-loop radiator concept described in 'All the Radiators'. Thin wires are dragged through a heat exchanger, absorb heat, then radiate it as they are rolled into the vacuum of space like a clothes line. <br /><br />Thinner wires have better surface area to weight ratios, so their performance improves. High specific strength materials can allow for very very thin wires strong enough to remain under tension while the spacecraft accelerates. An example is genetically modified spiders drinking carbon nanotube-laced water and producing very strong spider silk. It can be spun into fibers and used in wire loop radiators. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-85509976595535207212017-09-25T11:10:04.445+01:002017-09-25T11:10:04.445+01:00The link is blocked to me for some reason, but thi...The link is blocked to me for some reason, but this is already the principle of operation of a radiator: it radiates heat to outer space. This is the only way to get rid of heat for a spacecraft, actually. Apart from using a heat sink, but this is a temporary solution as at some point the heat sink will be filled/depleted.<br /><br />As for thermoelectric generators, they work on a heat gradient: you have a hot object, a cold object, and heat flowing between those can be partially tapped for energy. But at some point, you have to get rid of the heat in the cold object or it heats up and there is no gradient anymore. This is what the radiator does.<br />Note: you could use colder radiators have a bigger heat gradient and thus more energy, but then the colder radiator have to be much, much bigger to get rid of the same quantity of heat.<br /><br />Now, when you are relaxing the standards and allow not-too-hard SF, little bits of magic can help. For example, the ~100% efficient torch Epstein drive of the Expanse. Similarly, you can have sort-of magical ~100% efficient weapons.<br />You can also decide that your FTL gizmo allows for dumping heat directly into hyperspace somehow - be careful with the implications, though, such a system probably many, many secondary applications that will have to be carefully thought out.Ethhttps://www.blogger.com/profile/13196257853962186227noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-63202317467613866552017-09-25T07:23:17.065+01:002017-09-25T07:23:17.065+01:00OK, I started writing the space opera novel (with ...OK, I started writing the space opera novel (with heavily armored battleships having glowing dust plasma wings firing gauss cannons and deploying casaba howitzer missiles with HEAT warheads yay!) and I needed to come up with an alternative to dust plasma radiators for another competing faction in the storyline (this other faction uses genome manipulation instead of physics based tech).<br /><br />I asked this on the worldbuilding forums on stackexchange and one contributor suggested this:<br /><br />https://spectrum.ieee.org/tech-talk/green-tech/solar/passive-radiators-cool-by-sending-heat-straight-to-outer-space<br /><br />A passive radiator that shunts heat directly into space. Could this be possible?<br /><br /><br />Also, what about liquid or gas transferred thermo electric generators?John Triptychhttps://jtriptych.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-9905154556790212922017-09-01T11:45:33.809+01:002017-09-01T11:45:33.809+01:00You probably ARE going to want at least one layer ...You probably ARE going to want at least one layer of actual solid shielding. Notably, this will be part of what naval designers call a "citadel", which is a "box" of armour surrounding the most important parts of the ship (it does not cover bow, stern, or superstructures). Whether part of a citadel or not, the solid armour would be necessary to protect against explosive shells. While sand and whipple shields might be sufficient protection even against ultra-high velocitiy kinetic projectiles that tend to distribute energy inward (as do explosive penetrator rounds, which are NOT the kind of explosive shells I am talking about here), an explosive shell is designed to partly pentrate into armour before it explodes. In this case, the explosion creates a LOT of lateral force that is meant to widen gaps in armour, as well as outward force that will rip armour away. Sand and whipple shields are fairly useless against such traditional shells.<br />For an idea of how to put this together, I suggest you search "Iowa class battleship armour arrangement". The Iowa class had an outer skin, as well as four separate interior hull shins (sometimes labeled as "SHD", numbered 1-4 moving inward... and NOT including the outer skin). Each of these hull layers had a "void" between them, some of which were used as fuel storage or drinking water storage. SHD#3 was the armour plate, and SHD#4 was mostly to catch spalling. I would suggest a similar arrangement, replacing SHD#2, SHD#3, and the void between as the zone for alternating "sand" and whipple shield layers. The outer void (void#1) would be filled with water (or water ice), and the outer skin would be a lightweight solid armour layer.<br />Note that what I am suggesting here would be a warship design. It would be much too heavy for a stealth craft, although it would probably integrate some stealth features, mostly to make it more difficult for accurate targeting.<br />Smaller vessels and craft would more likely rely on manoeuverability for protection. Although lasers can move quickly, it is extremely difficult to move them precisely at great distances.Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-39153817014122853252017-08-31T14:55:38.362+01:002017-08-31T14:55:38.362+01:00Got it! So a hull with multiple layers of Whipple ...Got it! So a hull with multiple layers of Whipple shields that can move around and in between will be fields of metallic sand. This is awesome.<br /><br />So it looks like I've got the ship defenses thought out, now on to the weapons! Thanks, all.John Triptychhttps://jtriptych.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-88100542190893583992017-08-31T13:27:05.454+01:002017-08-31T13:27:05.454+01:00@John Triptych,
Having it cover the outer hull wou...@John Triptych,<br />Having it cover the outer hull would not be a problem. However, there are certain drawbacks to covering the entirety of a hull. Among these arethe need for certain items to be exposed in orderto function properly, and the mass involved in trying to cover everything.<br /><br />@Matter Beam,<br />Yes, solid matter holds together much better. However, it is also that much more difficult to repair, and to move around. In short, it is much, much easier to take advantage of burn throughs in solid matter, and much more difficult to fill in these burn throughs.<br />Another issue is that being held together is not actually that much of a deterent against lasers (it is far more useful against kinetic weapons).<br />A good compromise would be to alternate layers of solid shielding with "sand" shielding.Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-44587425400595031352017-08-31T02:58:19.569+01:002017-08-31T02:58:19.569+01:00The same flux-pinning used for the flux-pinner sup...The same flux-pinning used for the flux-pinner superthermal radiator concept (see the 'All the Radiators" blog post) can be made to hold metallic sand in place. <br /><br />However, such a shield is useful only if you want to replace armor depleted by an attack or if the magnetic fields holding the particles in place is greater than the electrostatic forces holding the particles together if they were a solid. If it is the not the case, it is better to just use segmented solid plates that physically shift to cover gaps. <br /><br />Basically, unless you have magnetic field strengths of thousands of Tesla, then it is better to just use solid plates. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-86012523567358857212017-08-30T16:12:51.707+01:002017-08-30T16:12:51.707+01:00Thanks, Mikkel! Excellent point. My question is wo...Thanks, Mikkel! Excellent point. My question is would it be possible to "shape" the metallic sand (either through advanced magnetic fields or nanites) into an outer bubble to cover the entire ship's hull like the shields they have in Star Trek?John Triptychhttps://jtriptych.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-88153147514574852032017-08-30T11:37:36.660+01:002017-08-30T11:37:36.660+01:00It is unlikely that the plasma wings will be of mu...It is unlikely that the plasma wings will be of much use against lasers. The particle densities will probably be MUCH too low (by several orders of magnitude). However, I suggested somewhere (I don't remember if it was here or not) that a similar sheet of metallic sand might be useful, in a similar arrangement. The "sand" could be semi-bound through even micro-g attraction, surface tension, etc; and could be reinforced through the use of electric currents and/or magnetic fields. <br />Even better might be to suspend the "sand" in a high-viscosity gel, to allow more fluid motion. The main idea is that these layers can be much more easily reinforced in case of attack. You would probably get a burn-through of considerable depth, but it would be easier to recapture fragments, and fill-in burn-through holes/craters. There would therefor be much reduced opprtunity for the enemy to take advantage of burn-through from previous beams.Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-1505576099515879122017-08-30T11:21:08.616+01:002017-08-30T11:21:08.616+01:00Yes, K=1 would probably be a rather rare exception...Yes, K=1 would probably be a rather rare exception. However, it is probably about as good as any other single value for a single case scenario.<br />For clarification: I was assuming that K was addressing ADDITIONAL divergence factors, assuming a specific given wavelength (in other words, assuming a fixed value for lamda, it addresses reflector specific conditions that could modify the divergence). I made this assumption because F1 already appears to take divergence into consideration. Thus, I don't think that the wavelength values in this most recent post are relevent to K value variations.<br />For K=1, the divergence of the reflected beam should be the same as the incident beam, which is the value dependent upon wavelength. Instead, variations leading to 1>K would probably tend to be the result either of (convex) lensing (a beam passing through uneven transparent/translucent layers), or larger reflecting surface area (same as using a larger mirror for the original beam). Variations leading to K>1 would result from from rougher surfaces (diffusion effects), concave lensing, reduced reflecting area, etc. K=1 would probably require an absolutely smooth, polished surface.<br /><br />It isn't exactly a "different standard", as such. There are benefits and drawbacks to RF. An important drawback is that useful imaging resolution is virtually impossible at any meaningful distance. Another important drawback is that non-metallic materials tend to be transparent/translucent to large swaths of RF. Even metallic materials become increasingly transparent.<br />One benefit is that you have MUCH less energy per photon. Therefore, the photon flux for even very weak RF signals tend to be huge. This means that detection ranges can be huge (unfortunately, this doesn't work so well for DAR sensors, because of the decreased reflectivity of RF).<br />A second important benefit is that RF is generally not subject to blackbody interference. Most blackbody emissions begin in IR ranges. Although very intense BB emissions can expand into RF wavelengths, the actual photon flu from such emissions are still relatively weak, especially for longer wavelengths. This means that the receiver does not have to be colder than the source to avoid interference. All this is because RF emissions are produced by different means. Again, it is not because they don't behave like other photons.<br /><br />Addressing radio stealth: it is still quite viable. RADAR stealth is viable, even with powerful transmitters, because of the habit of RF to transmit THROUGH materials, rather than reflecting. Thus, it is actually rather difficult to get a good detection signal (especially if anything reflected is going in the wrong direction). Direct radio stealth is achieved by restricting radio emissions. RF is generally not produced by BB radiation, except at the very highest intensities... and even then the emission levels are fairly low. This means that you need to generate it through other means to be detected... and this is fairly easily shielded because, although most materials are rather poor at reflecting RF, they tend to be much better at absorbing RF.<br /> Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-35174799709336016602017-08-30T11:09:14.306+01:002017-08-30T11:09:14.306+01:00Wow, thanks! I never thought if it that way. I'...Wow, thanks! I never thought if it that way. I'm assuming that these plasma wings will glow from the radiation, giving it the effect of looking like wings made of energy, am I right? If that is the case the ship designs would resemble birds, butterflies or even the old sailing ships!<br /><br />Could these plasma wings be used for defense against lasers too?John Triptychhttps://jtriptych.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-66733964184387273072017-08-30T02:20:01.051+01:002017-08-30T02:20:01.051+01:00I might have to write a dedicated 'how to deal...I might have to write a dedicated 'how to deal with active detection' in the future. <br /><br />For now, I've found that K=1 is not necessarily true in the majority of cases. It can be incredibly small for short wavelengths reflecting of an extremely smooth hemispherical surface. It can become very large for certain radio wavelengths reflecting off an object with a large RCS.<br /><br />Also, radio sensitivity seems to follow different standards than optical sensitivity. Instead of W/m^2 values, all I can find is decibels, which implies that if the sensor platform is sufficiently shielded from unwanted radiations, then it can detect radio signals a few billionth W/m^2 above the universal background radio signal!! It makes a strong case for radio stealth only being really achievable with counter-electronic warfare measures, such as decoys, jammers and spoofing. To be further investigated. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-19865281846175997562017-08-30T02:13:04.355+01:002017-08-30T02:13:04.355+01:00Agreed. That would be the maximal practical densit...Agreed. That would be the maximal practical density of droplets in a sheet.Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-13094157356642533472017-08-30T02:12:05.133+01:002017-08-30T02:12:05.133+01:00Hi John! I'd be glad to assist you.
Armored no...Hi John! I'd be glad to assist you.<br />Armored nose cone, rotating ring for habitation, sounds good so far. <br /><br />Radiators need exposed surface area to remove heat from their coolant flow. Enclosing them in armor is counterproductive. Fusion exhaust is much much hotter than any radiator's coolant fluids, so since heat will move down a temperature gradient, the effect will be contrary to what we want. <br /><br />What I would suggest is to use plasma wings held in place by magnetic fields extending beyond the hull. The plasma holds tiny particles within it. This is the basis for dusty plasma.<br /><br />The dusty plasma can circulate the particles in a loop from a heat exchanger to the vacuum of space to cool them down, and back again. The plasma wings will give you a great freedom of choice for the shape of your hull. <br /><br />Shooting these plasma wings is like shooting a cloud. You'd need massive amounts of energy to disperse it, and then it can be recreated with a few grams of material. Convenient! Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-13105865893888208052017-08-29T17:09:03.183+01:002017-08-29T17:09:03.183+01:00Interesting. I'm currently brainstorming for a...Interesting. I'm currently brainstorming for a far future space opera setting with some hard sci-fi elements so the shape of the warships is of a particular issue.<br /><br />I have imagined the lead ship to look like a spike with a ring around its base- that would be the habitable section that would retract (and stop spinning) during combat. <br /><br />My question is- can a liquid droplet radiator be enclosed around armor so it would act as sort of an internal coolant protected by the hull? Can the radiator emissions be redirected as part of its fusion drive exhaust?John Triptychhttps://jtriptych.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-42458495703133452312017-08-25T11:25:55.144+01:002017-08-25T11:25:55.144+01:00BTW:
I have been actually been assuming that both...BTW:<br /><br />I have been actually been assuming that both detection and transmission platforms are capable of full spherical coverage, either through the presence of multiple units, and/or the use of scanning. Note that the latter option adds some inherent problems that could further limit detectability.Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-58339604592380009642017-08-25T11:22:21.489+01:002017-08-25T11:22:21.489+01:00It is worth noting that there IS one factor that h...It is worth noting that there IS one factor that helps reduce the total number of platforms required. Notably, any asset will have to eventually pass through a number of zones. For a well established network, it is unlikely that any gaps in coverage will occur in the same angular region (respective to the asset) in all zones. This means that you might do okay with even 10% probability coverage, if the asset has to travel through dozens of zones.<br />There is some risk with this, of course. With the resulting intermittent coverage, it can be difficult, if not impossible, to identify if you are tracking a single asset, or if you are dealing with multiple assets operating it relatively close proximity (within adjacent zones of arbitrary size).Anonymoushttps://www.blogger.com/profile/08104586551355707368noreply@blogger.com