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Project Apollo Beta 7.0 released!
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Author Topic: Virtual AGC  (Read 166138 times)
indy91
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« Reply #675 on: October 05, 2016, 03:13:37 PM »

The simulations might be interesting for us... although they probably only have to be as accurate as the simuated AGC needs. So Zerlina56 is my favourite of the documents left, too.
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thewonderidiot
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« Reply #676 on: October 05, 2016, 07:11:30 PM »

The simulations have some pages of setup information for the AGC, so it's possible that we might get the equivalent of a pad load out of them. Wink No promises, though. Either way, that Zerlina simulation is going to be our best bet at finding such numbers for it.
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kneecaps
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« Reply #677 on: October 05, 2016, 07:23:22 PM »

The simulations have some pages of setup information for the AGC, so it's possible that we might get the equivalent of a pad load out of them. Wink No promises, though. Either way, that Zerlina simulation is going to be our best bet at finding such numbers for it.

Regarding pad loads, I wonder if we might simply be able to make a request for such information. They must exist somewhere.

I'm so stoked by all these new docs, even the YUL source code and the fabled RETREAD.

So are we thinking the Zerlina software and sim?

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"Okay. As soon as we find the Earth, we will do it."
- Frank Borman, Apollo 8

Current Work: ?? What next??

Future Work:
I know the AGC pretty well so anything need doing there?

On Hold/Completed:
SPS TVC in P40 issues.
P11 FDAI Error Needles (98%) complete. Comitted. Working A7 scenario.
P06 AGC Standby. Concluded. It's done by the AGC PSU.
Got us a complete AOH Volume II
indy91
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« Reply #678 on: October 06, 2016, 08:39:03 AM »

Regarding pad loads, I wonder if we might simply be able to make a request for such information. They must exist somewhere.

I mean, we have two LM Pad Load documents and parts of CMC pad loads in the Apollo 14-16 G&C Checklists. We also have the pad load mostly figured out for our three CMC versions. But at least one complete CMC pad load, preferably Apollo 8 or 9, would be very nice to confirm that what we have figured out ourselves over the years is correct. Especially the TVC parameters and maybe some flagword presettings.
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kneecaps
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« Reply #679 on: October 06, 2016, 10:23:43 PM »

Regarding pad loads, I wonder if we might simply be able to make a request for such information. They must exist somewhere.

I mean, we have two LM Pad Load documents and parts of CMC pad loads in the Apollo 14-16 G&C Checklists. We also have the pad load mostly figured out for our three CMC versions. But at least one complete CMC pad load, preferably Apollo 8 or 9, would be very nice to confirm that what we have figured out ourselves over the years is correct. Especially the TVC parameters and maybe some flagword presettings.

Okay, I will reach out to Ron Burkey and Fabrizio Bernadini, i've not been in direct contact with either for several years but I'm sure the would be willing to make requests for the pad loads.
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"Okay. As soon as we find the Earth, we will do it."
- Frank Borman, Apollo 8

Current Work: ?? What next??

Future Work:
I know the AGC pretty well so anything need doing there?

On Hold/Completed:
SPS TVC in P40 issues.
P11 FDAI Error Needles (98%) complete. Comitted. Working A7 scenario.
P06 AGC Standby. Concluded. It's done by the AGC PSU.
Got us a complete AOH Volume II
indy91
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« Reply #680 on: October 07, 2016, 06:18:36 AM »

I am not sure there is much hope for more pad load documents right now, but I am sure Ron would know the right people to ask. I've been in a lot of contact recently with Ron, since he and @thewonderidiot helped us with some Virtual AGC bugs that prevented successfull lunar landings. I have also implemented in our version of the AGC engine whatever changes have been done to the Virtual AGC in the last few weeks. The most recent topic was standby mode (https://github.com/rburkey2005/virtualagc/pull/164), which I haven't implemented yet.

@kneecaps, your signature seems to indicate that you have worked on such things in the past. I am having a little bit of a hard time working out what changes have to be done to NASSP for the Virtual AGC standbye mode, so if you want to take a look at it, that would be great.
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kneecaps
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« Reply #681 on: October 07, 2016, 11:31:54 PM »

I am not sure there is much hope for more pad load documents right now, but I am sure Ron would know the right people to ask. I've been in a lot of contact recently with Ron, since he and @thewonderidiot helped us with some Virtual AGC bugs that prevented successfull lunar landings. I have also implemented in our version of the AGC engine whatever changes have been done to the Virtual AGC in the last few weeks. The most recent topic was standby mode (https://github.com/rburkey2005/virtualagc/pull/164), which I haven't implemented yet.

@kneecaps, your signature seems to indicate that you have worked on such things in the past. I am having a little bit of a hard time working out what changes have to be done to NASSP for the Virtual AGC standbye mode, so if you want to take a look at it, that would be great.

Good work on all fronts! Well with standby mode I concluded that it was essentially done as a hardware function of the AGC (specfically part of the power supply electronics). I'll see what changes have been made on yaAGC itself.

Edit: I've had a quick look and it does appear that the hardware elements to perform the standby are now provided as part of yaAGC. Also since some of the timing scalers were not phased correctly (as discussed here somewhere I recall), those corrections would likely improve the behaviour of timing sensitive flight code!
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"Okay. As soon as we find the Earth, we will do it."
- Frank Borman, Apollo 8

Current Work: ?? What next??

Future Work:
I know the AGC pretty well so anything need doing there?

On Hold/Completed:
SPS TVC in P40 issues.
P11 FDAI Error Needles (98%) complete. Comitted. Working A7 scenario.
P06 AGC Standby. Concluded. It's done by the AGC PSU.
Got us a complete AOH Volume II
thewonderidiot
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« Reply #682 on: October 08, 2016, 02:53:49 AM »

Unless I've horribly broken something (which has certainly happened before), the only timer phasing difference with this set of changes should be a shift of TIME6 counts to 0.3125ms after TIME1 increments. My gut feeling is that this shouldn't have that much of an impact on behavior, but I'd be happy to be wrong.  Very Happy
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indy91
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« Reply #683 on: October 08, 2016, 07:46:49 AM »

If anything correct TIME6 phasing will improve the RCS DAP of the LGC.

But what I was really getting at with asking for help, is that every day I work on Virtual ACG topics that are not important for Apollo 7+8, the 7.0 release happens one day later. I would really like to focus on getting the Checklist MFD files ready and fixing any exisiting bugs in MCC, RTCC or RTCC MFD. I would also like to see the standby mode being implemented, so I thought someone else could take over work on our Virtual AGC for now.
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kneecaps
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« Reply #684 on: October 08, 2016, 06:57:52 PM »

If anything correct TIME6 phasing will improve the RCS DAP of the LGC.

But what I was really getting at with asking for help, is that every day I work on Virtual ACG topics that are not important for Apollo 7+8, the 7.0 release happens one day later. I would really like to focus on getting the Checklist MFD files ready and fixing any exisiting bugs in MCC, RTCC or RTCC MFD. I would also like to see the standby mode being implemented, so I thought someone else could take over work on our Virtual AGC for now.

Are we thinking that the proper standby mode would be needed for Orbiter time acceleration? As the function wasn't used in real flights?

 
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"Okay. As soon as we find the Earth, we will do it."
- Frank Borman, Apollo 8

Current Work: ?? What next??

Future Work:
I know the AGC pretty well so anything need doing there?

On Hold/Completed:
SPS TVC in P40 issues.
P11 FDAI Error Needles (98%) complete. Comitted. Working A7 scenario.
P06 AGC Standby. Concluded. It's done by the AGC PSU.
Got us a complete AOH Volume II
eddievhfan1984
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« Reply #685 on: October 08, 2016, 07:06:07 PM »

Well, the original Apollo 7 flight plan called for drifting flight with the computer in standby to check CMC/IMU restart capabilities. It would be worth adding just for feature completeness and emergency checklist ops.
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kneecaps
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« Reply #686 on: October 08, 2016, 07:27:17 PM »

Well, the original Apollo 7 flight plan called for drifting flight with the computer in standby to check CMC/IMU restart capabilities. It would be worth adding just for feature completeness and emergency checklist ops.

Ahhh, I didn't know this. Did they actually perform it during the flight?

Agreed, it should definitely be in the checklists/working capability.
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"Okay. As soon as we find the Earth, we will do it."
- Frank Borman, Apollo 8

Current Work: ?? What next??

Future Work:
I know the AGC pretty well so anything need doing there?

On Hold/Completed:
SPS TVC in P40 issues.
P11 FDAI Error Needles (98%) complete. Comitted. Working A7 scenario.
P06 AGC Standby. Concluded. It's done by the AGC PSU.
Got us a complete AOH Volume II
indy91
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« Reply #687 on: October 08, 2016, 11:37:16 PM »

Ahhh, I didn't know this. Did they actually perform it during the flight?

According to the Apollo 7 Mission Report they did use P05 and P06 during the flight, so I think they did it as written in the preliminary flight plan, power down of the guidance and control systems during the sleep period. Reading the transcript for the relevant times could confirm that. There also is a very preliminary summary flight plan for Apollo 8 from September 1968 that also had the power downs each day, but after Apollo 7 everything worked so great, that there wasn't really a good reason to voluntarily loose alignment etc.

There is a standby mode implemented for the AGC++, so the changes to the CSMcomputer and LMcomputer classes ideally shouldn't break that.
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indy91
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« Reply #688 on: October 09, 2016, 10:02:05 AM »

I have now been getting a pretty bad clock problem, too, but in the CSM. After about 70h into the Apollo 7 mission the CMC clock is off by about 20 seconds and looking at old scenarios it has been getting progressively worse throughout the mission. @thewonderidiot, is it possible that any of the AGC engine changes in the last few months could have caused this? The clock already was off before I played around with the standy mode changes to the AGC engine. And @rcflyinghokie had/has a pretty bad problem with this in the LM, so maybe it was one of the first changes to the AGC engine done for the PDI issues.
« Last Edit: October 09, 2016, 10:12:43 AM by indy91 » Logged
thewonderidiot
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« Reply #689 on: October 09, 2016, 12:50:26 PM »

My math doesn't line up with exactly 20 seconds, but I found and fixed this: https://github.com/rburkey2005/virtualagc/commit/e30fefb1ace7abd318b0c7a4b3bf08f1cbde1eb0

That would skew the clock by 1/3200 of a second every 5.12 seconds (or 1/1600 of a second pre-standby-addition). That's in the same ballpark of error, at least.
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