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Project Apollo - NASSP 6.4.3 released!
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Author Topic: Apollo 8 Beta Testing Bugs  (Read 17354 times)
indy91
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« Reply #195 on: February 16, 2017, 11:04:52 AM »

The only issue I see with the scn files so far (and it is very trivial) is that the RCS Logic breakers are in during most of the mission.  They should be opened after CM/SIVB sep and I believe not closed again until CM RCS checks before CM/SM sep.  I can fix this if you all want.

Alex will fix it. EDIT: Or you already did it Very Happy

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On another note, the 8 CMP checklist has the NONESS BUS being switched to MN B before P40 SPS burns.  However I cannot find mention of the NONESS breaker being closed.  Would it be safe to assume this breaker was closed before launch since no other documentation (that I have seen) mentions the NONESS breaker?

Hmm, The later launch checklists have the circuit breaker open and I can't find any reference to closing it. Later missions also don't have the switch setting in the P40 checklist. Maybe this is a CSM-103 only thing with special sensors on that bus.
« Last Edit: February 16, 2017, 11:10:42 AM by indy91 » Logged
jalexb88
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« Reply #196 on: February 16, 2017, 11:11:03 AM »

EDIT:  I have fixed the scn files to reflect the RCS LOGIC breakers

Sounds good!    EDIT:   In the Apollo 8 - 12 - Entry Preparations T+142h40min, I forgot to set the ROT CTRL PWR 1 & 2 from OFF back to AC/DC. Do you mind fixing that?
« Last Edit: February 16, 2017, 11:14:02 AM by jalexb88 » Logged
rcflyinghokie
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« Reply #197 on: February 16, 2017, 11:19:18 AM »

Alex will fix it. EDIT: Or you already did it Very Happy
Haha yeah, figured while I had them open might as well!

Hmm, The later launch checklists have the circuit breaker open and I can't find any reference to closing it. Later missions also don't have the switch setting in the P40 checklist. Maybe this is a CSM-103 only thing with special sensors on that bus.

I couldn't either which is why, given our lack of a true prelaunch checklist for 8, I think it may have been closed for launch as I cannot find another point where it would actually be closed.  Also I found in the Pre SC Sep addendum in the TL LOI TEI procedures, the NONESS is also assumed to be on MN B prior to sep, which begs the question since it was not turned on in the launch/insertion checklists, was it also turned on in prelaunch?


Sounds good!    EDIT:   In the Apollo 8 - 12 - Entry Preparations T+142h40min, I forgot to set the ROT CTRL PWR 1 & 2 from OFF back to AC/DC. Do you mind fixing that?

So they should be on AC/DC when you load that scn correct?

EDIT:  For the NONESS, the TL LOI TEI procedures also has the NONESS switched from MN B to MN A 2mins prior to SEP and then no record of switching it off.  I think you are right about there perhaps being some CSM 103 specific instrumentation on that bus.  Where would be a good source to find out?
« Last Edit: February 16, 2017, 11:26:00 AM by rcflyinghokie » Logged
jalexb88
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« Reply #198 on: February 16, 2017, 11:23:18 AM »

So they should be on AC/DC when you load that scn correct?

Yep should be on...the reason I turn them off is in case I bump my controller during time accel.
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rcflyinghokie
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« Reply #199 on: February 16, 2017, 11:28:02 AM »

I have fixed the scn files, I have not, however messed with the NONESS breaker or pre sep switching until we find out a little more about this.  Clearly they have no effect on our sim at the moment anyways so we can always change those down the road should we add power draw from that bus at a later date when we re examine the CSM power system.
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eddievhfan1984
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« Reply #200 on: February 16, 2017, 02:00:46 PM »

unless that SMa upper limit is smaller than the nominal return...

That is exactly the issue and why the -MA procedure had to be used. Both for the nominal Apollo 8 return and some abort cases. The maximum major axis P37 allows in Colossus I and IA (Apollo 8 and 9) is 8e8. Take half of that and you have the maximum semi-major axis. 4e8 is about a lunar distance, how they ever thought that was going to be enough...

Maybe it was intended for a minimum-dV abort from the Moon more than anything else, in which case it would suffice?
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indy91
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« Reply #201 on: February 16, 2017, 02:42:20 PM »

The Apollo 8 Spacecraft Operational Trajectory from October 25th 1968 still had a return 24h later as the nominal trajectory. In that case Entry Interface would have been at 171:05:32 GET with an entry velocity of 36071 ft/s. It also mentions the return one day earlier as an option, which is of course the trajectory that was then flown. So, with that trajectory there probably wouldn't have been a problem with P37.

Maybe it was intended for a minimum-dV abort from the Moon more than anything else, in which case it would suffice?

It suffices for all direct return aborts, yeah, not for the nominal return trajectory from a lunar orbit though.
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meik84
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« Reply #202 on: February 16, 2017, 04:26:20 PM »

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Maybe this is a CSM-103 only thing with special sensors on that bus.
I guess the FQR (flight qualification recorder -not to be confused with the DSE) was on the noness bus. AFAIK they wanted more data from the SPS when in deep space.
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indy91
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« Reply #203 on: February 16, 2017, 04:37:24 PM »

I guess the FQR (flight qualification recorder -not to be confused with the DSE) was on the noness bus. AFAIK they wanted more data from the SPS when in deep space.

Apollo 7, too. An early CSM-101 Systems Handbook (http://wayback.archive-it.org/all/20100525065443/http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720067986_1972067986.pdf) has 6 FQR circuit breakers on a panel 277, and those are powered by Non-Essential Bus 1.
« Last Edit: February 16, 2017, 05:00:49 PM by indy91 » Logged
eddievhfan1984
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« Reply #204 on: February 16, 2017, 07:57:25 PM »

Well, I did a ground-calculated version of the abort burn from TEC. Definitely works from that perspective, and I made it with about 2% SPS propellant. However. for whatever reason, P37 in precision mode won't converge on a new solution afterwards—it'll find the conic solution after I set up the -MA option, and be just fine with it, but it throws the program alarm during precision iteration that I've exceeded the number of permissible loops, though before the alarm is thrown, the SV time is within an hour of the ground-calculated EI.
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indy91
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« Reply #205 on: February 17, 2017, 06:17:55 AM »

Do you have a scenario after the RTCC calculated burn? Maybe you are running into some other kind of constraint in the precision phase. Or P37 can't deal wth something else on that trajectory. It must have been a really long burn, if you only have 2% of SPS propellant left.
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rcflyinghokie
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« Reply #206 on: February 17, 2017, 11:42:39 AM »

I have not check in Apollo 7 yet, but is anyone else getting a "drogues" verbal sound effect when they are deployed after entry in Apollo 8?  I do not think this is from orbiter sound as I couldn't find the effect.
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jalexb88
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« Reply #207 on: February 17, 2017, 11:49:57 AM »

I have not check in Apollo 7 yet, but is anyone else getting a "drogues" verbal sound effect when they are deployed after entry in Apollo 8?  I do not think this is from orbiter sound as I couldn't find the effect.

I do get that, but only after I load a scenario/quicksave just before entry interface. If I fly a scenario all the way from MCC-7 or entry preparations to splashdown, I dont hear that sound effect.
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eddievhfan1984
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« Reply #208 on: February 17, 2017, 02:00:40 PM »

Do you have a scenario after the RTCC calculated burn? Maybe you are running into some other kind of constraint in the precision phase. Or P37 can't deal wth something else on that trajectory. It must have been a really long burn, if you only have 2% of SPS propellant left.

2:21 burn time. I really thought it'd have to finish it off with RCS for a while.

I've attached the scenario, and selected abort mode in the MCC menu (which probably doesn't do anything after TEI anyways). The parameters from my last P37 after the burn should still be in there; I moved the TIG forward 15 minutes when the first iteration failed, according to the CMP checklist.

* (Current state).scn (103.93 KB - downloaded 50 times.)
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indy91
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« Reply #209 on: February 17, 2017, 02:21:43 PM »

The Drogues sound is from NASSP. So it's a feature, not a bug. If it only happens with saving/loading shortly before EI then there might be something wrong with handling of the different CM stages though. No idea.

I've attached the scenario, and selected abort mode in the MCC menu (which probably doesn't do anything after TEI anyways). The parameters from my last P37 after the burn should still be in there; I moved the TIG forward 15 minutes when the first iteration failed, according to the CMP checklist.

RTCC MFD gives a 1.2 ft/s corridor control burn at EI-2. Then I tried the normal Apollo 8 -MA procedure and got a 130 ft/s conic phase solution and the 605 alarm for exceeding iterations in the precision phase. The 130 ft/s solution is weird and I might have done an error in the procedure somewhere. Instead of the 70000E,E for the -MA I then tried the hardcode values used for Apollo 10 and later. Those values are 75725E, 75417E. With that the conic phase gives me a good solution about 1.3 ft/s. The precision phase fails again due to iteration limit. I will investigate this further. However, the reentry is faster than usual, 36800 ft/s with an angle of -6.62°. So maybe there is some other constraint that prevents P37 from working there. Although, that problem should then also happen with the RTCC MFD entry targeting...
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