[23:22:39] NASSP Logging has been started by thewonderidiot [23:22:43] GuenterWendt! [23:30:13] I guess my modem is acting up again after not having issues for a couple of months. [23:30:24] Sounds like it's time for fiber. [15:13:35] hey [15:17:14] good morning [15:21:21] I have been testing various cases for Apollo 7 with drag in MATLAB [15:21:33] specifically what phasing maneuver we need [15:22:01] drag-free DV is 1.7 ft/s [15:22:19] if the S-IVB stays in the least draggy attitude we would need about 2.9 ft/s [15:22:26] with realistic drag [15:23:01] in reality the S-IVB at some point has used up all its APS propellant [15:23:20] so it will start to tumbling, which means on average it has a larger drag area [15:23:57] I can replicate the worst case quite nicely, the operational trajectory has a worst case area and I get the same DV, 7.7 ft/s [15:24:33] actual mission used 5.7 ft/s which ended up being too litle so they had to do a second phasing maneuver [15:38:09] thats very promising [15:38:21] is this drag applied to all vehicles? [15:38:29] (thinking the CSM/LM for Apollo 9) [15:40:48] I'll probably end up giving all vehicles a drag coefficient of 2.0 in all attitudes. And probably tweak the drag area for all of them a bit. [15:41:29] does this take orbital altitude into account? [15:41:45] yeah Orbiter has a quite accuravy density calculation [15:41:52] accurate* [15:42:41] the aerodynamic properties of the atmosphere seem to change a bit below 80NM or so [15:42:49] smaller drag coefficients in the CSM Data Book [15:43:06] but the 2.0 is quite accurate for higher altitudes [15:43:56] it's a slight issue for Apollo 5 where the S-IVB already exists on the launchpad [15:44:31] The way I have it set up right now is that if S-IB and/or CSM/LM are docked to the S-IVB then the CD is nearly 0 for forwards and backwards motion [15:44:54] will this have impact on boost phase? [15:45:05] for Apollo 5 yes [15:45:10] other missions? [15:45:13] nah [15:45:25] I'm not changing the aerodynamics of the Saturn launch configurations [15:45:29] ok cool [15:45:30] only separated CSM, LM and S-IVB [15:45:50] I was going to say we have those looking pretty good with the real world masses and such haha [15:46:16] I mean, the launch stages don't very perfect aerdynamics either [15:46:28] but I'm mostly interested in orbital drag right now [15:46:57] right right, I just didnt know if these would impact other phases of flight [15:49:19] right, it would but those vessels don't exist on launch yet, only for Apollo 5 [15:49:55] and it's the most simple aerodynamics model in Orbiter, too. Can always be improved [15:52:35] yeah, the orbital stuff is good for now of course, especially for RTCC computations and the like [15:53:05] so the SIVB would get a little drag during TLI now [15:53:46] yeah. LVDC will need to use its drag calculations [15:54:50] shouldn't be too bad though. Not that much drag and not that much time spend in that orbit without LH2 vent [15:55:19] not like the 24 hours on Apollo 7 with a very lightweight S-IVB [15:56:47] right [16:05:31] in terms of targeting, I'm sure they will have used the prelaunch estimate for the first phasing maneuver [16:05:39] and some trial and error for the second one [16:05:56] that's how I'll implement it as well [16:06:08] not using Lambert targeting anymore for it [16:16:56] will that give you the underestimated DV? [16:17:04] requiring the additional phasing [16:18:59] not 100% sure yet. Depends how the S-IVB really behaves in NASSP. I don't think I have ever seen it properly tumble [16:19:14] I will first test it with the minimum drag [16:19:35] so 2.9 ft/s for the first phasing and then trial and error using minimum drag, too [16:19:41] for second phasing [16:20:00] another thing we do wrong right now is the APS propellant [16:20:12] the amount loaded is different for S-IVB 200 vs. 500 series [16:20:17] 200 has a lot less [16:20:33] but we only use the 500 series amount [16:20:49] so the S-IVB might not even have run out of prop at the time of rendezvous [16:38:54] how is the scenario editing going? LM ECS branch ready soon? [16:43:21] morning! [16:45:06] hey Mike [16:51:21] Yesterday snuck up on me work wise, I am going to be resuming 9 here shortly after a 1300 meeting (in 10 mins) [16:51:36] I'd like to be done this evening or tomorrow [16:52:06] great [16:54:01] I'm merging the branch where I implemented the lunar launch window targeting for the MCC. Have done enough testing for it I think [16:54:25] and as planned I will merge my LM EPS branch not until your ECS branch gets merged [16:55:57] I think I'll start with the drag update and Apollo 7 MCC updates now [17:33:28] hey [17:41:45] well lookie who we have here [17:42:02] good to see you AlexB_88! [17:43:08] hey Ryan :) [17:43:39] yeah I've been a bit distracted lately with other things [17:45:29] hows the new IRC network so far? [17:46:12] hey Alex [17:46:48] I had some connection trouble earlier lol. But it was the first time and no idea if it really was a problem with the network. [17:48:23] ah, right [17:48:28] so far its good for me [17:49:22] Yeah I havent seen much difference from freenode on my end [17:49:34] looks like you pushed that RTE stuff you were working on a few weeks ago, Ill have to give that a whirl! [17:50:03] yeah, got that done some time ago [17:53:35] freenode had a further meltdown yesterday -- they went and deleted every single registered channel and user, and created a "new" freenode that is entirely separate from the old freenode network [17:53:40] so it's well and truly dead now [17:54:29] wow [17:57:23] well good call on jumping when we did! [18:01:48] yep [18:17:31] Thymo: libera has a webchat feature now that might be worth linking in your IRC post on the forum: https://web.libera.chat/ [18:18:28] or better yet, https://web.libera.chat/?channel=#nassp [18:19:49] oh but you already linked one through kiwiirc directly [18:19:52] nevermind, ignore me :) [18:29:28] Ok only Apollo 9 left to do [18:29:38] making good progress [18:30:06] cya! [19:12:49] Ok 23 Apollo 9 scns left to edit then done, gotta resume tomorrow though lol [20:30:24] thewonderidiot: Yeah, KiwiIRC was the way to go while they didn't have their own webchat. Looks like this is basically a redirect. [20:34:45] cya! [13:38:35] hey [13:41:25] morning [13:43:06] learned something new. No CSM flown on a Saturn IB had an UP TLM switch for the IU [13:44:39] seems to always be enabled for a digital command system in a AS-200 S-IVB [13:44:56] for Skylab and ASTP the spot for that switch is simply empty [13:45:42] Apollo 7 had a switch there, but the panel diagrams I have aren't very high res. It has the switch positions record and rewing. Probably something for the flight qualification instrumentation only flown on Apollo 7. [13:45:54] rewind* [13:46:31] Apollo 7 S-IVB had a IU navigation update after CSM sep that I never implemented, that's why I was researching this. [13:54:11] huh, that's interesting [14:00:58] hey random question. is there Fortran source avaliable any of these RTCC routines that we have documentation for? [14:01:40] basically no [14:01:48] there are bits and pieces in MSC memos [14:02:13] but only rarely are they going to be 1:1 as programmed in the RTCC [14:04:24] https://web.archive.org/web/20100519203534/http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750065854_1975065854.pdf [14:04:43] this has FORTRAN code that is closely related to the actual development for the RTC [14:04:44] C [14:07:33] like, I am pretty sure the function to calculate atmospheric density in there is essentially the same as in the RTCC [14:07:53] closely agrees with the flow chart in the IBM RTCC document [14:11:45] I've been talking with Richard Cornwell (kiteguy on the pdp-10 channel, he popped on here once) and with his help I managed to get his IBM 7094 emulator running ibsys and compiling and running FORTRAN IV jobs. [14:12:28] so I've been feeding it any code I can find [14:13:32] ah fun [14:13:44] that document has some pretty complex code [14:14:31] https://web.archive.org/web/20100527004127/http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19700026563_1970026563.pdf [14:14:40] I'm also pretty sure that the RTCC had this routine, probably 1:1 [14:15:19] that's a bit simpler, one page [14:16:51] rcflyinghokie, you made a good point when you asked which vehicles would be affected by a drag update. I don't think I can get away with leaving the CSM+S-IVB configuration as it is in terms of drag. [14:17:11] but then, especially for the Saturn IB, it operates at lower altitudes as well [14:17:59] and using a CD of 2 in all attitudes might not be good enough for lower attitudes. I might have to use the airfoil system, the standard Orbiter aerodynamics. [14:18:08] altitudes* [14:21:10] sorry was in a meeting...catching up in IRC... [14:22:12] might need some experimenting [14:22:37] But yeah we have many different vehicles and combinations that have to take the atmosphere into account (especially 7 and 9) [14:24:11] I'm happy to use the simple system with only a SetCW call for CSM, S-VB and LM [14:25:04] that's using the numbers from the CSM Data Book, which apparently applies to orbital velocity and altitudes about 450k feet [14:25:14] above* [14:26:20] yeah I dont think it will have any major impact [14:27:01] but I'd also like to give the CSM+S-IVB configuration the same aerodynamics for LVDC navigation mainly [14:28:08] but that can operate at lower altitudes, at least directly after staging [14:29:54] Saturn IB staging happens at about 60km [14:36:00] right [15:16:08] the Orbiter airfoil function gives Reynolds number as a parameter [15:16:31] that could be used to decide which parameters to use [15:16:43] continuum flow vs. free molecular flow [16:41:39] yeah I think I'll implement airfoils for everything. I think I can get it quite realistic without being too complicated [17:24:14] morning! [17:30:58] hey Mike [17:33:40] what's up? [17:34:28] implementing some aerodynamics functions [17:34:41] mainly 3rd stage configuration, so CSM+S-IVB [17:36:03] this configuration can operate at lower altitudes where the aerodynamics are a bit different. So the legacy aerodynamics model in Orbiter, constant coefficients of drag at all altitudes and velocities, isn't quite good enough [17:40:47] mainly relevant for the Saturn IB which stages at about 60km and then has the CSM+S-IVB [17:41:19] oh nice [17:42:26] the main method in Orbiter to implement aerodynamics is implement a function that returns the coefficients of lift, drag, moment [17:42:48] quite powerful, Orbiter gives you Mach and Reynolds number [17:43:11] which I am using to calculate: https://en.wikipedia.org/wiki/Knudsen_number [17:43:46] the value of that decides between free flow and continuum flow. For those two we have sets of coefficients in the CSM Data Book [17:44:05] I don't have good numbers for the Saturn stages though [17:44:41] hmmmm [17:45:16] CSM+S-IVB and CSM have roughly the same shape though, right? :D [17:45:26] I feel like I remember seeing a lot of aerodynamics stuff from when we were doing the mass NTRS scraping.... [17:45:31] hahaha sure :P [17:46:00] I have collected a lot of stuff about the Launch Escape Vehicle [17:46:12] I have one document about the abort vehicle [17:46:21] that is, S-IC + S-II + S-IVB and CSM missing [17:46:27] or CM missing [18:33:23] "Study of drag coefficients for unusual vehicle configurations" is apparently a document that has orbital drag parameters for the Saturn [18:33:35] but we don't have it [18:33:43] restricted NTRS has it [20:52:26] night! [13:49:39] hello [13:54:22] hey [14:28:41] I'm finding too little sources on S-IVB orbital drag. And the sources I am finding for the most part disagree with each other :D [14:55:00] hmm [14:55:45] OpenFOAM has a DSMC solver.... [15:03:42] would be very hard to get sensible and useable results though [15:06:20] yeah [15:07:01] we do know the numbers that the LVDC uses [15:08:25] maybe the solution for free molecular flow is simply to make it compatible with the LVDC orbital navigation [16:53:36] well, I managed to compile that HANGLE subroutine you showed me yesterday [16:57:09] getting weird output though [16:58:21] morning! [17:01:26] hey [17:09:47] hey Mike