[14:53:39] NASSP Logging has been started by n7275 [14:53:41] good morning [15:02:29] hey [15:22:09] have our Saturn IB and V a better drag model during first stage flight [15:22:11] gave* [15:22:17] still very simple [15:22:21] but a bit better [15:22:31] finally depends on Mach number :D [15:25:16] oh awesome [15:26:22] I know exactly which documents would have good numbers, but exactly those documents are not available [15:26:45] instead we have the same type of document for the aborted Saturn V [15:26:46] that's sadly usually the case [15:26:53] so S-IC + S-II and S-IVB but no CSM [15:27:16] but I think I've collected enough information for this simple model at least [15:27:41] I really want to add moment coefficients, too, as the vehicle are slightly instable in certain Mach regions [15:27:52] https://i.stack.imgur.com/d2eSh.png [15:27:55] slightly scared it will be bad at low frame rates haha [15:28:01] yeah [15:36:26] https://cdn.discordapp.com/attachments/780878788216881173/821574218654679060/p.png [15:40:25] Saturn V winning Olympic Gold against the ML in Wrestling [15:45:00] yep haha [15:45:37] on the other hand, right now we get an angle of attack during launch that is a bit too large, because there are no stabilizing moments [15:45:54] also leads to a bit more drag with my current model [16:08:21] morning! [16:17:46] hey Mike [16:21:56] what's up? [16:38:26] I may or may not have just accidentally deleted the container containing the new wiki's database... [16:38:53] Guess it's time to import everything all over again [16:45:02] oh no. [16:49:12] that doesn't sound good [16:52:12] Meh, I just need to run the maintenance scripts again to reimport all the pages and images, then recreate my account and tweak all settings. Mean I get to wait while that;s running again [17:15:33] thewonderidiot, you scanned too many things, I had to spend like 1 minute to find a specific document that Ron hadn't put up yet haha [17:19:56] the "Preliminary" Apollo 7 Flight Crew Abbreviated Checklist [17:20:06] it isn't as preliminary as the title page suggests [17:20:11] because it has updated page [17:20:16] that go up to September 1968 [17:20:23] so just before launch basically [17:20:44] I kind of want to change our Apollo 7 checklists based on that [17:20:48] but that's a lot of work :D [17:31:54] oh hahaha [17:32:18] I'm not sorry for scanning too much :D [17:34:39] yeah seems like the first part of that document is quite like the CSM Launch Checklist of the later missions [17:35:30] and it's the final document of this, so very good to have [17:35:43] the title page suggested it was from 1967 [17:36:31] it also has the SM RCS test firing on the pad [17:36:41] don't think we have safely do that in NASSP yet [17:36:43] the rocket would move [17:37:56] oh awesome [17:39:13] can safely* [17:43:21] yeah I've been having a lot of fun finding unexpectedly good things in the scans lol [17:43:33] I really did not look at most of these things too closely [17:45:55] yeah will be a while until we have properly digested it all [17:46:40] hmm, I gave the Saturn IB a moment coefficient that is way too strong and has the wrong sign [17:46:58] in other words, auto aborts due to large attitude rate is still working [17:53:59] haha, that must be fun to see [17:58:58] well it wasn't on purpose [17:59:02] but still fun to see [18:02:40] hehehehe [19:54:11] well, past the 200hr mark now [20:07:47] :D [20:42:34] How am I supposed to interprete NARAs reproduction fees? I found a document listed as 2 linear feet stored in 5 boxes, I see two different rates, one listed as "paper-to-paper" at $0.80 per copy and another as "Oversized and per linear foot" at $3.50 per linear foot. Which one applies? [20:42:35] https://www.archives.gov/research/order/fees [20:43:05] This is the document https://catalog.archives.gov/id/990772 [20:44:08] If it's $0.80 per page its gonna cost a small fortune to have scanned and I'm not sure how many pages it even has. [20:46:49] that's not a document, that's 5 boxes full of documents that are roughly categorized as checkout procedures [20:47:31] you're certainly looking at thousands of pages there [20:48:02] and that $0.80 per page is a fixed rate, you're reading that right [20:49:16] the "per linear foot" is talking about oversize materials -- things that are multiple feet long or tall [20:49:26] like a poster [20:50:07] Oh, I see it now. "Series". I thought I had found a nice document specifying a lot of before T-4H stuff. [20:51:47] Know anyone in Washington with nothing to do that knows how to operate a scanner? :P [21:02:42] NARA-SW might actually have the same documents if not a more recent version [21:06:07] Both actually. One listed as 2 ft. Same as in Washington. There is another entry for CSM checkout procedures listed at a whopping 24 feet! [21:09:08] yeah [21:09:14] there is a *lot* at NARA [21:15:54] I think I could sit there for days surrounded by towers of boxes [21:16:26] Maybe it's in my own best interest the archives are on a different continent [21:21:08] lol [21:47:21] thewonderidiot, what's volunteer program like? [21:47:27] ^NARA's [21:50:34] n7275: you mean like the kind of volunteer that Ron is? [21:54:18] it'd be better to ask Ron directly about it, but it's a bit more involved than the "volunteer" title suggests [21:54:54] there's a lot of paperwork to fill out, and you need to get recommendations from people who can attest to your archival history... or something like that [21:55:09] Ron said it was kind of like a job application [21:55:54] Yeah, I imagine it's fairly involved. [21:55:58] I will ask Ron [21:56:18] Are you interested in becoming a volunteer? [21:57:37] also from Ron: "The truth is that there are no enhanced privileges as a volunteer. The rules for volunteers explicitly guarantee there aren't any extra privileges. The sole reason I'm able to get these aperture cards for free (even though it's against the rules for volunteers) is that it was agreed-upon in advance and therefore has become a sanctioned activity. " [21:58:24] not really, since I'm nowhere near any of the archives and there isn't that much to be gained [21:59:33] oh I mean I'm not, I can't speak for Matt haha [21:59:44] We'll I'm in Maine, so that's about as far from anything as you can be. [21:59:53] heh [22:01:52] Sounds like there wouldn't be much point to it then. [13:58:35] hey [13:59:57] good morning [14:23:27] about the LVDC navigation update, I think in the end it still is definitely an improvement [14:23:34] not by as much as I thought but still good [14:24:12] getting very consistent results and orbital navigation isn't contributing any additional error as far as I can see [14:24:37] so any idea where the remaining error is coming from? [14:24:40] yes [14:24:42] all boost [14:24:55] Hey guys [14:25:00] Yeah that makes sense then [14:25:15] Is the large IMU torque after insertion a result of that error as well? [14:25:32] Morning Thymo [14:25:56] hey [14:26:00] hmm good question [14:26:16] I think the alignment is actually correct [14:26:28] it's the REFSMMAT that gets calculated at liftoff that is slightly off [14:27:01] because of non-spherical Earth assumption in the AGC [14:27:15] state vector is also quite off after launch in the CMC because of that [14:28:17] And we have a sphere in Orbiter [14:28:30] yes [14:28:49] some errors are expected and I think they make up at least a decent part of the error [14:29:02] the integration scheme [14:29:09] that would be interesting to be able to fix in Orbiter now [14:29:16] not taking into account the third and fourth harmonics in the boost navigation [14:30:27] those cause an error that just makes the state vector worse over time [14:30:58] in all scenarios I get a quite consistent error [14:31:09] 11,000 ft downrange at 1:45h GET [14:31:35] and that error is already predicted to happen after insertion, so not a contribution of orbital navigation [14:32:17] and that's well within even the strict Apollo 17 mission rule for a IU nav update [14:32:58] so if it really cuts the error we previously got in half in every scenario then we should really not need any IU uplink [14:33:10] and that is better than all actual missions I think [14:33:33] but to be fair, the main error source for orbital navigation is propulsive venting which is somewhat random [14:33:40] and we don't have that yet [14:36:03] one error source that the actual missions didn't have of course is staging [14:36:16] at staging the center of gravity of our Saturn is shifted [14:38:57] wonder if any timestep issues occur then as well [14:39:36] yeah maybe [14:39:57] those of course happen a few times during boost and can lend to error propagation [14:40:12] in any case, I think I am done with LVDC navigation for now, it should be better than before at least [14:42:14] any improvement is a good thing [14:44:21] there was a never ending confusion about the J3 harmonic, or "H" as the LVDC code calls it [14:44:32] we did in fact use the wrong sign for it [14:45:13] the LVOTs don't agree on the sign and our two source for orbital navigation didn't either [14:46:06] but I check the gravity vector against what the AGC calculates and I know which sign gives the correct result haha [14:46:09] checked* [14:58:35] good morning [15:03:12] hey Matt [15:18:48] I'm in the home stretch of Apollo 7 now. one more sps burn, then deorbit [15:19:29] the O2 and H2 stratification tests are making me want to work on systems again [15:24:41] I might need to let the LM lose more heat during TLC than it gains [15:24:56] I mean nothing is off scale high but it just seems higher than I'd like [15:25:09] hmm, Apollo 7... [15:25:44] the Earth Entry PAD has a tailoff DV [15:25:58] basically what the EMS will show at the end of the burn, so not at cutoff [15:26:10] I think that might not be implemented yet [15:26:18] probably hardcoded to 0 [15:27:51] yeah [15:27:55] need to fix that [15:37:49] got deleted from the Apollo 9 version of that PAD though [15:37:54] but we use the Apollo 7 one [15:39:36] oh I found something useful on the archived NTRS earlier [15:39:52] rare these days, we have almost gotten everything good from it by now... [15:40:02] Operational Data Book for Skylab [15:40:10] quite like the one for CSM and LM [15:40:15] 1200 pages [15:42:07] I was looking for drag coefficients for Skylab. Found the title of a document, looked at the restricted NTRS list and it was there. I was 99.9% sure it would be one of the not available documents, but I was wrong. [15:43:14] morning! [15:43:16] oh man [15:44:15] I found 3 volumes of it [15:44:21] 2 others are about experiments and stuff [15:44:39] the CSM Data Book would be another volume of it, but it's not available. [15:44:49] Something interesting, in the 16 LM activation checklist, the initial cb positions have the ASA cb open [15:44:51] I knew that about the CSM one [15:45:44] I also found the "Skylab Operational Command Listing" [15:45:59] basically all commands you could send to Skylab, CMC, IU [15:46:15] damn that's some good stuff [15:46:37] 16 and 17 both have the ASA open... [15:47:44] that seems odd [15:49:12] Well confirmed in the apollo 17 closeout pics ASA is indeed open [15:50:05] does that affect the heater? [15:51:45] Pretty sure [15:51:50] At least in earlier LMs [15:52:03] Apollo 15 has the breaker in [15:59:54] But in the LM 11 volume 2, it looks like it's open for prelaunch yet closed on the initial entry [16:01:31] but thats not in the activation checklist [16:03:05] so not closed until activation power up CB chart [16:04:59] in the LM activation checklists yes [16:05:10] however the AOH vol 2 has it closed during initial entry status checks [16:09:18] I trust the activation checklist over the AOH for what actually was done [16:11:13] yep same here...and the closeout photo of panel 16 for 17 confirms that being out [16:12:13] https://history.nasa.gov/alsj/a17/LM12-co8.jpg [16:12:20] https://history.nasa.gov/alsj/a17/LM12-co22.jpg [16:14:05] huh 15's seems out as well [16:14:06] https://history.nasa.gov/alsj/a15/lm10-co13.jpg [16:14:30] hmm maybe not [16:15:09] iiiinteresting [16:15:14] https://history.nasa.gov/alsj/a15/lm10-co14.jpg this one it looks in but it could just be the angle [16:15:18] I think its out [16:15:25] the flight copy of the Apollo 15 LM Activation Checklist has a comment about it being open [16:15:39] oh? [16:16:07] have a link? [16:16:10] https://readux.ecds.emory.edu/books/readux:sc5zx/pages/readux:sc688/ [16:16:52] don't think that means they should open it, they also changed the number of open CBs on the right [16:17:03] I think that means it should have been open [16:17:11] as shown in the closeout photos [16:17:23] yeah, so just like 16 and 17 [16:17:45] Wonder if there was any demonstration about the ASA being able to warm up later and be accurate [16:18:04] Or if it was due to additional heaters (MESA) being necessary [16:19:07] I guess 13 demonstrated the ASA could cool down and warm up and be accurate [16:24:32] right [16:28:10] interesting info for the J mission LMs [18:18:21] indy91 can you explain the differences in the LS and LS during TLC REFSMMATS? [18:19:13] so, the LS REFSMMAT as the AGC also calculates it in P52 option 4 you need a CSM state vector, as that defines the orbital plane of the CSM [18:19:33] how do you get that CSM state vector in TLC [18:19:44] you have to do all the effort like the LOI-2 REFSMMAT for Apollo 8 [18:20:07] which I think is the only way the real mission could do it, of course with the help of the MPT [18:20:23] the "LS during TLC" method defines the CSM orbital plane with the approach azimuth [18:20:43] and the landing site coordinates [18:21:01] so that works without a CSM state vector in lunar orbit at the landing time [18:21:13] I don't think the real RTCC had a method like that though [18:21:23] but it's much easier and nearly as accurate [18:23:06] it uses the approach azimuth from the LOI processor inputs [18:23:45] but once you are past LOI-2/DOI the LS REFSMMAT should be calculated using the CSM orbit [18:24:22] there is always a REFSMMAT update in lunar orbit before landing and it's always been very small compared to "LS during TLC" [18:27:22] makes perfect sense [18:32:01] hmm did I miss something? Was Apollo 16's flight pushed back for some reason? [18:32:12] Their prelim LOI was 4 hours after mine [18:32:19] and the flight plan [18:33:40] Oh wow [18:33:49] Disregard I had 15's open [18:35:19] oh speaking about 16, do you have a pre TLI scenario for me? I wanted to see how it does in terms of overburning/underburning [18:35:52] without implementing the post TLI LH2 venting, maybe it could improve accuracy a little bit if I bias the cutoff by the same amount that the LH2 vent was supposed to be [18:36:08] I think it was 0.26 m/s [18:36:50] so I am curious where the pericynthion altitude is in your Apollo 16 scenario [18:36:57] I should yes one moment [18:37:03] with IU nav update, so I need pre TLI [18:37:27] Take the caveat that the launch was done on my laptop, so timestep/frames could have had an impact [18:37:36] right [18:38:01] with a fresh SV the IU should be happy [18:42:05] 10m before tb6 ok? [18:42:08] yep [18:42:21] https://www.dropbox.com/s/udk47h4usinvggc/Apollo%2016%20-%20TLI.scn?dl=0 [18:42:43] in terms of IU state vector accuracy, there used to be a bug at liftoff that made the accuracy worse if you had a bad framerate [18:42:46] thanks! [18:43:30] so not sure how much that is still a factor [19:17:32] rcflyinghokie1, with a IU nav update I get a 3 ft/s MCC-2 at 30h GET [19:17:36] unconstrained [19:17:42] 5 ft/s with time constraint [19:18:00] thats really good [19:18:19] I would only make that worse when I mess around with the cutoff bias again, so I think I'll leave it alone :D [19:18:36] pericynthion altitude after TLI cutoff is 120NM or so [19:18:37] considering 16 burned 12.5fps [19:18:55] it means the presettings are good at least [19:19:11] The mission report shows 146.7 after TLI [19:19:14] and the cutoff bias agrees with the actual tailoff thrust [19:19:45] so hopefully with the now better orbital navigation TLI should be less of a problem [19:20:03] very nice [19:20:55] :D [19:22:01] well I really wanted to do this test to see if we now get a slight underburn because of missing LH2 venting [19:22:09] but we don't soo, test failed? :D [19:23:29] well the PC is still a little low [19:24:19] not compared to the planned number [19:24:25] that is 71.4NM [19:25:00] but the sensitivity is very high for that [19:25:15] 279 NM difference in PC altitude per 1 ft/s TLI cutoff difference [19:25:40] so basically nearly perfect [19:32:51] Fair enough! [19:36:04] you just have to look at the THC and your pericynthion has already changed by 10NM [19:39:36] Haha [19:55:22] LOI looks like its going to be a good one based on the pad and calcs [19:55:36] less dvz than actual [19:56:55] actual: -2781.6 -219.6 -256.2 RTCC: -2793 -233.3 -161.5 [20:01:15] yeah looks similar, actual mission rotating the orbit a bit more with the DVZ [20:19:45] very good burn [20:19:53] 0.6 on the EMS [20:20:23] -.2 -.2 0 on the N85 [20:20:56] 170x59.3 on N44 [20:26:37] I hope that's a -0.6 on the EMS [20:27:14] and even that should be even more negative I would think [20:27:31] unless you put in the total DV and not the DVC [20:30:41] with DVC the EMS should have -6.0 [20:40:56] sorry it was a +0.6 [20:42:03] Ahh [20:42:10] yep I used VT [20:43:17] Rookie mistake haha [20:54:02] previously the values were nearly the same [20:54:11] but not exactly, especially not for LOI [20:54:26] EMS accelerometer is along the X-axis of the CSM [20:54:38] but the thrust vector isn't exactly the same [20:55:04] so even before we got a 1-2 ft/s or so difference of DVT and DVC [20:55:37] the Detailed Maneuver Table shows the tailoff DV separately [20:55:53] so if you wanted the EMS to end exactly at 0 after a burn you could add DVC and DV TO [20:56:03] not sure if they ever did that for a maneuver [21:03:44] the RTCC maneuver simulation even has separate values for total DV of tailoff and tailoff DV along the x-axis like for the EMS [21:03:53] now that is not a very significant difference :D [21:05:15] Quickly cutting in here. Has any of you ever seen a panel 201 with a food warmer switch/cb? I'm listening to the baseline CSM configuration from the Apollo 13 tapes and I don't recall every seeing that. [21:09:04] there is a ACA utilitiy switch on a panel 201 [21:09:06] AC* [21:09:12] not sure if we have that [21:09:43] AC utility* [21:10:19] Same thing but relabeled maybe? [21:11:39] maybe [21:11:47] AOH mentions the food warmer switch [21:11:54] Volume 1 [21:11:56] We don't have CSM-109s system handbook. [21:12:00] OH. What page? [21:12:01] page 2.12-80 [21:15:19] I'm gonna check the CSM112-114 system handbook but I don't think we have this. [21:15:33] 104 systems handbook doesn't have the panel at all [21:15:57] It probably would go into AC utility as it is a stowed device. Probably relabeled [21:16:46] it's not even in the Apollo 14 Launch Checklist [21:16:57] the checklist starts with a list of initial switch states [21:17:06] or at liftoff rather [21:18:59] The system handbook still shows the switch as "AC Util" [21:20:18] seems like the other way around, food warmer until at least Apollo 13 and then later it's AC Util [21:20:38] That would make more sense [21:28:05] night! [22:02:15] .ask indy91 So about that Skylab document. you have a link or a hint of where I should look? I'm interested in it. [22:07:37] I can probably dig it up [22:07:40] actually [22:26:18] Awesome [22:26:21] thank you [22:27:08] it took us a bit to work that out lol [22:27:44] it's also possible, but a bit more difficult, to map a document number of the form Nyy-xxxxx (where yy is a year) to an NTRS ID [22:30:07] ahh [22:34:15] :) [22:41:02] I have a fairly large collection of offline documents now. [22:42:49] I used to have a bunch of shuttle docs circa 2007. at some point, I just figured I'd always be able to access them and stopped maintaining the archive [22:43:05] which was dumb [22:45:49] hah yeah having offline backups is always good [22:46:15] speaking of, I've been meaning to buy a big drive and back up all of the listings and engineering drawings and things we've added to archive.org..... I should do that this week [23:10:46] brb [10:29:55] .tell indy91 nevermind, Mike hooked me up with it and and showed me how to find stuff like this [11:00:16] Hey Matt [11:35:27] hey Thymo [11:41:10] what's up? [11:42:27] Listening to Apollo 13 again while working. They just read up the LM to CM power procedure. Also taking a glance at the ECA on the side to figure out how they made it work without disconnecting the batteries. [11:43:45] Also got the FLIGHT loop in one ear where they are discussing if the PLSS LCG water is safe to drink and optionally feeding it into a ASC water tank to use with the sublimator. [11:55:26] oh cool [11:56:59] They opted not to fill the tank because the tank would need to be empty (which took 30 hours) so that the delta pressure could push the water from the PLSS to the ascent tank and they're afraid the water in the DES tank would've frozen by then so they rather use that first. [11:57:58] Fred Haise also suggested this independantly but with the urine bags. That also wasn't done due to the 30 hours it takes to use that tank. [12:01:01] They also appeared to have done of the descent batteries short out causing a thump and venting from the descent stage. It was believed this was the relief valve on the ambient helium tank but post-flight they determined this was a small hydrogen explosion causing electrolyte to leak. [12:01:24] This was also shown in the telemetry [12:01:25] https://history.nasa.gov/afj/ap13fj/pics/battery-transients.png [12:01:38] Bus voltage dips and BAT 2 amps are off scale high [12:02:03] woah [12:02:13] They are going to get a battery fault light later but I haven't gotten there yet. [12:02:33] https://history.nasa.gov/afj/ap13fj/pics/battery-terminal.png [12:02:47] It's assumed the battery leaked and then caused the terminals to short [12:09:28] n7275: Also have you ever read something about what the X LUNAR BUS breaker was for? The X LUNAR BUS is also connected by a relay when CSM power is applied, the breaker only bypasses this breaker. I'm wondering if it's just there for contigency purposes if that relay fails to latch or if there's more to it. [12:12:25] huh, I have no idea [12:15:55] Hmm, I think I know. [12:16:33] The relays are operated by the DES ECAs so if for some reason you needed CSM power after staging or in case of DES ECA failure you would need to use the breaker to tie in the X LUNAR BUS [12:16:52] So I don't think it was used in normal situations [12:17:10] .ask rcflyinghokie Do you know if the X LUNAR BUS was closed as part of any normal non-contingency checklist? [12:41:21] I still have a bunch of systems work to do for proper Apollo 13 fuel cell deaths [12:41:43] Like the electrolyte solidifying and stuff? [12:47:52] eventually, but salt-water phase simulation is fairly complex. first I want more stable pressures to the cells, so I can make voltage proportional to the reactant pressures [12:48:10] I guess you also want PH stuff at some point [12:48:32] then "clogging" can be done by partial pressure and "contaminating" the O2 tank with n2 [12:49:35] There was also some stuff about KOH contamination in the fuell cells in the mission rules. Don't know where that would be coming from though [12:50:00] Isn't the electrolyte made out of that stuff? [12:51:33] yeah' KOH and water [12:52:11] there are teflon seals that keep the electrolite, H2 and O2 seperate [12:52:30] those can break down over 550F or so [13:03:22] then the steam+KOH mix leaks out and activates the pH sensor [13:26:52] Hey Ryan [13:28:44] morning [13:29:03] It was closed whenever the LM went under internal power [13:30:20] It was necessary to tie the negative returns since some LM systems were "grounded" via the xlunar bus and others vis the CDR/LMP negative busses [13:34:38] Hmm. I can see that. There is no such thing as CDR or LMP negative bus. Equipment usually used frame ground in the LM. I don't know of any equipment grounded to the x lunar bus though. AFAIK that bus only exists to bring the LM and CSM to the same reference as the CM did use a negative return bus instead of frame ground. [13:36:47] It looks like the systems that were used on CSM power indeed use the x lunar bus as their ground reference, so in that case it makes sense for that breaker to be in when those systems are used on lm power [13:36:54] Actually there are a few systems grounded through the xlunar bus, and there are CDR/LMP negative busses [13:37:21] The systems on the xlunar bus were those that were intended to be powered via CM (Nik and I went though a few weeks of this research haha) [13:40:03] I can find only one mention of a negative bus in the systems handbook and that is on the AC power drawing. It says the DC input and AC output of the inverters are tied to two separate negative buses which are both tied to structure ground. So would it really qualify as a bus if it's permanently bonded to structure ground? [13:40:17] That also doesn't matter for the x lunar bus tie breakers [13:40:44] the negative busses in this case are floating grounds, and they are grounded to the frame [13:40:51] but they are denoted as negative busses [13:41:14] In what situation are they not grounded to the frame? [13:41:40] If they are always grounded it's not floating [13:42:17] the xlunar negative busses are floating grounds [13:42:36] the CDR/LMP negative busses are frame grounded [13:43:00] the xlunar bus tie ties those floating grounds to the CDR/LMP negative busses which are grounded to the frame [13:44:33] Where are the CDR LMP neg. buses described? They are not on the drawing I'm looking at. [13:45:55] Which are you using? And they are all in the AOH for example [13:46:16] I'm looking at the LM10 AOH Vol.1 and the LM-3 systems handbook [13:47:00] The only two negative buses in the AOH are the x lunar bus and the ED negative bus [13:48:08] Haha I have the LM 10 AOH up looking at many -bus examples :P [13:48:25] page [13:49:47] for example look at pdf 356 [13:49:53] the CSM/LM power transfer logic [13:51:10] Those buses don't exist in the systems handbook [13:51:37] And I trust that more than this simplified diagram [13:52:24] Haha we went through all of this recently [13:52:36] I've sent a screenshot of how that is drawn in the systems handbook. No bus to be seen [13:52:40] On Discord [13:53:10] Yes I have that open [13:53:50] the frame ground is denoting the negative bus [13:54:19] So you agree that "CDR negative bus" is just a convenience term used in the AOH and not an actual bus [13:54:21] and the floating grounds are the xlunar negative busses [13:54:37] As in the drawing they are tied together but there is no actual bus to speak of [13:54:54] Are you asking if there is a physical bus bar versus just being frame grounded [13:55:13] I'm not asking I'm stating how I see it. [14:00:14] well in the functional schematics there is what looks like a physical negative bus [14:04:56] "DN2" appear to be physical bus bars [14:06:29] on the other topic of the apollo 8 scns starting P37 when you load them he is correct [14:09:21] Okay so -DN2 are actual bus bars. I assume there is also -DN1 then. I just find the name "CDR/LMP - BUS" confusing as in the CSM the negative bus is the reference point where in the LM that is just a convenience bus bar to bond it to chassis ground. I also don't think there is any other place than that one AOH drawing that refers to it by that name. [14:10:11] In my mind it implies that there is a separate ground reference point other than frame ground and the x lunarbus in the LM. [14:10:44]