[15:53:02] NASSP Logging has been started by thewonderidiot [15:53:04] morning! [15:53:37] indy91, sorry I got pulled away yesterday [15:54:03] but yes. also did you know that EDDs have a separately bound Parts 3 & 4 volume, filled to the brim with the flowcharts that Ron was trying to replicate? [15:55:15] nooooooo I didn't know that :D [15:55:24] also, hello [15:55:54] the EDDs are both earlier than the one we already have? The one we have does not have anything on e.g. the timebase 5 for deorbiting the S-IVB with a propellant dump [15:56:00] so it's likely not the last version [15:56:04] despite being from April 1972 [15:57:09] so upon looking more closely at these, there's one totally complete one, and then one that's actually 3 sets of change pages all bound together [15:57:26] the totally complete one is March 25, 1975 [15:57:41] specifically reprinted for ASTP [15:57:48] oh that is awesome [15:59:01] the sets of change pages are from April 23 1973 and January 22 1973 [15:59:08] so, all later than the current EDD [15:59:55] I like it very much [16:02:17] Parts 3 and 4 look insanely useful [16:02:33] :D [16:02:46] documentation for almost every routine, what it does, what variables uses and what they are, what inputs are required, flowcharts [16:03:01] it's too bad I didn't manage to find one of these for the Saturn V [16:03:37] now I want one even more haha [16:04:02] I never did the "generalized flight program" update for our Saturn IB LVDC [16:04:11] only for the Saturn V one [16:04:24] but maybe with those flowcharts it would be worth it [20:43:24] night! [14:58:35] hey [15:11:39] morning! [15:12:36] what's up? [15:16:04] mostly work. been spending a lot of time scrubbing the layer of dirt and junk off of the CDUs lol [15:16:32] haha [15:16:57] that's part of archeology [15:17:09] lol indeed [15:17:21] what about you? [15:19:40] putting a few pieces together for custom mission planning with TLI targeting. But I will go back into my SIVBPropulsion branch in a bit to tweak a few numbers so that RTCC and S-IVB agree about the amount of thrust of the propulsive LH2 venting [15:20:28] still not happy with how the pressures behave when the venting is off, but at least that doesn't cause any trajectory issues [15:20:48] just venting gaseous H2, so not even propellant being lost [15:21:01] overpressure venting I mean [15:21:07] when the propulsive venting is off [15:21:16] the pressure rises too much due to heat [15:22:02] the right amount of mass goes from liquid to gas though, so it must be a temperature or ullage volume issue [15:26:50] and I think LH2 is more compressible than your average liquid, right n7275? [15:28:49] hi [15:28:56] very compressible [15:29:22] yeah, that would mean the pressure doesn't rise as much when some liquid goes into gas [15:29:37] I think :D [15:30:01] I know, I know, all of this makes you want me to use a tank from our Systems SDK :D [15:30:13] hehehe [15:33:37] lol, I can see the pros and cons there haha [15:37:42] if a tank would be used then I would put the isolation factor to 0 at first [15:37:59] so that I can control all heat going in and out [15:38:29] with the current tank behavior, not your update, what sort of temperature range gives good behavior? [15:38:38] or is it suboptimal for every case [15:40:37] hmm the tank solution has more issues [15:40:53] like when the SIVBSystems are transferred from the Saturn to the S-IVB class [15:42:13] I think we should wait on the tank until we have docked stages [15:43:44] yeah [15:43:49] I'll not switch course now [15:44:04] if anything I will look into some ullage volume calculation [15:44:09] maybe that makes the behavior better [15:51:45] how warm does the liquid portion get? [15:52:36] hey [15:52:49] hey Alex [15:54:28] yo [15:58:13] hey Alex [15:58:30] n7275, I don't simulate the temperature [15:58:47] and I have a constant gas temperature [15:59:13] I just have a heat that theoretically goes into the liquid, but I just calculate a mass that evaporates immediately from that heat [16:04:03] oh I ment in the actual SIVb [16:05:55] hmm, I can look that up [16:06:13] but isn't it slightly irrelevant? There is just going to be some of it that evaporates [16:06:33] if it's getting warmer there is more of it going into gas [16:07:40] I do want to add a little bit heat for O2 as well actually. Just so that the rest of it evaporates eventually after passivation [16:08:46] I'm just curious how near to the critical temperature the liquid is. for H2 it's 33.2K [16:09:07] right, right [16:11:40] LH2 pump inlet temperature seems like a good measurement for it [16:12:13] about 38-39°R [16:12:20] 21-22K [16:14:28] there is also a LH2 bulk temperature measurement [16:14:33] but it's in a similar region [16:15:57] every temperature I see that is in contact with the liquid (so during burns, with LH2 actually flowing) is below 40°R [16:24:27] some quick math with densities and pressures says that the bulk modulus of LH2 at 20K should be around 450kPa [16:28:19] that seems low though... [16:30:22] the temperatures I am seeing in the documents or that pressure? [16:30:41] my calculated bulk modulus [16:30:54] don't trust that number [16:31:09] those temperatures make sense [16:31:32] I had put our substance simulation in a script last week [16:31:44] was going to play around with the behavior of a single tank like that [16:31:49] might try that some more now [16:32:09] oh, like a matlab version of ThermalComps? [16:32:14] yeah [16:32:25] do you understand everything h_substance::Condense and Boil do??? [16:32:31] there is some weird stuff with dt [16:32:39] must be preventing long timestep issues? [16:33:08] I plotted that at one point to make sense of it [16:33:25] I just put it in the script as is [16:33:26] *in an attempt to make sense of it [16:33:44] emphasis on the "attempt" [16:34:00] haha [16:34:07] I also have a Matlab version of our tank simulation [16:34:43] if I put the rough initial conditions from the flight evaluation report (liquid and gas masses at specific temperature) then I see a linear behavior of pressure, temperature and air volume [16:34:55] and it settles down [16:35:05] at 21.8 K [16:35:11] no heat input [16:35:42] I think I'll add a heat input and a bit of a CVS simulation to it [16:35:46] just to see how it will behave [16:37:01] everything using ThermalComps from your branch [16:37:24] if you have any plots I'd be interested in seeing those :) [16:37:56] sure [16:38:04] right now they aren't very interesting yet [16:38:19] it just settles down to stable conditions between liquid and gas [16:51:51] n7275, already ran into an issue. With pipe flow it seems to not consider the different phases. So there always flows a proportional amount of liquid and gas out of a tank that has a mixture [16:53:34] I could make it only take vapor_mass in my script, but then I'd have to add a Q calculation I think, as the amount of Q wouldn't be proprtional between liquid and gas, right? [18:19:58] correct [18:20:52] hmmmmmmmmmm I wonder if that is a problem in our code..... [18:22:02] I would like to think I did that any place that just liquid or just vapor mass are removed, but now I want to look again [18:28:49] I don't quite understand that sentence haha, sorry. Flow from tank to tank uses h_volume::Break [18:29:15] and h_volume overloads h_volume::operator += [18:29:41] and * [18:30:09] and I think they always take a proportional amount [18:30:19] temp.mass = mass * mult; [18:30:19] temp.Q = Q * mult; [18:30:20] temp.vapor_mass = vapor_mass * mult; [18:30:44] mult being the ratio of volume taken from the tank [18:31:05] I don't see any code that takes only liquid or only vapor [18:31:16] but maybe I am overlooking something [19:29:53] im back [19:30:24] thats good, i just wanted to check [19:34:16] just taking vapor_mass out of the tank with venting doesn't behave nicely [19:34:37] I could be copying some of the code wrong of course [19:34:48] it vents all of the gas [19:35:33] that is already with putting Q into it [19:35:56] temperature rises but not enough liquid becomes gas [19:38:08] oh yeah [19:38:13] I did copy something wrong I think [19:39:13] h_volume has a Q but has its own Q [19:39:27] h_substance has* [19:40:31] looks like it results in the same numbers if there is only one substance [19:46:03] I have issues with h_substance::Boil and Condense [19:46:12] vapor_mass += dt; [19:46:25] there are a few conditions that modify dt before this, but I am not hitting any of them [19:46:48] so the vapor mass just linearly grows with time, so kind of factor applied to it [19:51:09] no kind of* [20:17:54] I can work my way through the logic of *what* Boil and Condense are doing, but not *why* [20:19:58] hmm I see [20:20:15] there is no way it should work like this [20:20:46] I've just tried NASSP in debug mode and I am getting some cases at least where this logic is used [20:20:55] first timestep, 0.01 seconds [20:21:03] means 0.01 kg of vapor_mass is added [20:21:11] or I guess grams [20:21:46] yeah, grams [20:22:04] the code has always been like that though, I check it from the earliest commit we have on Github, 2009 [20:22:09] checked* [20:22:29] it's that way in the SPSDK source from 2003 I believe [20:24:05] It would probably make more sense ifthe boiling rate was proportional to the total mass of that substance in the tank [20:24:13] that basically makes it useless for my purpose, as it doesn't accurately simulate the amount of mass going from liquid to gas over time [20:24:47] This maybe another of the problems I ran into [20:25:09] I think I have some notes saved on it [20:26:31] anything that helps making those functions make more sense to me helps :D [20:27:34] but yeah, you can put as much heat into a tank as you want, it doesn't seem to actually boil more mass [20:27:42] it raises the temperature [20:27:49] I know I've seen a "delayed boiling" effect [20:27:53] with large tanks [20:28:03] and the tank you have is very large [20:28:11] yeah the effect would be more pronounced with large tanks [20:28:38] definitely large :D [20:29:27] and yeah, it doesn't boil when you put a lot of heat in, but on the other hand, it keeps boiling and increasing in pressure, long after you've stoppedd putting heat in. [20:29:43] *stopped [20:30:18] h_substance::VAPENTH [20:30:24] what does this calculate? [20:30:40] Enthalpy of vaporization [20:32:13] I guess its more like "heat of vaporization", not quite accurately named [20:32:59] if vapor_mass + ddt > mass - 1.0, I believe this tries to make sure there isn't more vapor_mass than mass [20:34:15] I think so [20:34:17] if Q < vapenth_temporary*ddt and because the vaporization takes Q from the substance, this tries to make sure the energey doesn't become negative [20:35:12] yes [20:35:44] but this [20:35:45] vapor_mass = vapor_mass + ddt; [20:35:48] surely is missing something [20:35:57] because in the normal case ddt is a time [20:36:29] one sec [20:36:50] the conditions for how much mass actually boils could be complicated, but I have no idea really [20:37:09] just looking at code that doesn't seem to correspond to physics :D [20:37:32] much of it sadly... [20:39:24] okay [20:39:35] sorry if ddt was confusing you, that was from my script [20:39:42] I didn't want to manipulate the actual dt [20:40:01] so I added some of this code, but its really just a drop in replacement for what was already in these functons [20:40:09] *functions [20:40:35] no worries, matlab c can be funny with things like that [20:40:45] yeah, that's how it seemed to me. You improved individual things in it, but you didn't make fundamental changes [20:40:46] *matlab can [20:41:39] it's a bit like trying to change a tire while driving [20:42:04] so, looking at the code, [20:42:15] that's why the RTCC has a couple of extra tires that I would like to get rid of, but they still somewhat touch the ground... [20:42:59] these physics say: boiling/condensing always happens at 1g/sec