Meadville Space Center

Project Apollo - NASSP => Support & Bugs => Topic started by: Admiral on February 04, 2008, 07:49:45 AM



Title: Apollo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on February 04, 2008, 07:49:45 AM
Hi all

I am new to the forums and have been working through the Apollo 8 FlightPlan over the last couple of weeks of the new year since the latest beta release on 15 Jan.

I am now at the 100 hour mark about to prepare for my final course correction before Earth reentry.

Well done to all for the very good work over a long period of time.  It is just sensational and you should be all very proud for the work you have achieved.  Well done.

Here is my feedback.
The checklists are of a very high quality and very easy to follow and very accurate.

Prelaunch, launch and separation worked fine

At my first state vector update at MET 08:00:00, I forgot to put in the launch mission time in the CMC update.xls.  (I recommend that this gets added to the excel Apollo 8 Flightplan, AGC worksheet as an instruction).  I was able to correct my mistake.

While on trans lunar coast my screen saver kicked in while on 10x warp.  I had a CTD when trying to regain the focus again.  I am running orbiter in a 1280 sized  window.

Between 052:30:00 MET (after 3rd P23 of the mission ) and 060:00:00 MET I noticed I had a constant Comp Activity light come on.

The 2nd mid course correction had prog error 1520 or error 1202 alarms occur at execute.  P00 would not set and the comp Activity light stayed on.

To fix, I did a V36 CMC restart procedure.  This cleared the comp activity light error and I performed an IMU recovery.  Interestingly I was out of both Earth and Moon SOI according to IMFD so did not do a state vector update until I was in th Moon SOI well after the burn.

No problems encountered with the Lunar insertion burn.  The only thing I found annoying was using the increment/decrement EMS wheel.  I couldn't refine it to exactly match the burn time.  I did get it close though.  I don't know if it can be programmed to be set using the mouse scroll wheel to adjust.

The circularisation burn ended up quite a bit shorter than it should have been.  Not sure why.

For the man set Roll, Pitch, Yaw scroll wheels.  I noticed if you decrease the butons from 001 to 000 (or 360 depending on you poinrt of view), 350 is displayed, then 359  is the next dowm, so just a minor display issue.


At 88:00:00, I left lunar orbit and had a constant Comp Activity light after that burn.  Another CMC reset fixed it

I am now at the 100 hour mark, and I've had another constant Comp Activity light and 1520 alarms at the next p23 program start.  I am testing to see if V96 is possible to use.  I seems it might temporarily delay the light enough to execute a procedure.  I am likely to do a cmc reset though.

The state vector updates after the first one were ok.  I key in the full 5 digits in the cmc (eg 00021) for each vextor.  It is a bit clunky to work with the copy and paste.  Is it possible to push the values to excel. Or if easier pushed to a text file on  v71 execution that can then be read and  imported via an excel macro as a simple alternative. 

The IMFD takes a bit of getting used to, but the more I use it, the more I see its power

I am performing all tasks listed in the flight plan and plenty of quicksaves along the way. 

With plenty of consumables left, I have just 45 hours to go until splashdown  I love this program. :D
The alarms along the way add to the realism and force good troubleshooting!



From The Admiral



Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: Tschachim on February 04, 2008, 10:23:35 AM
Thanks for your kind words and sharing your experiences!  :)

...The only thing I found annoying was using the increment/decrement EMS wheel.  I couldn't refine it to exactly match the burn time.  I did get it close though.

Use the right mouse button for fine tuning, also you need to set the delta velocity in ft/s, not the burn time: http://nassp.sf.net/wiki/EMS

Cheers
Tschachim


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: irnenginer on February 04, 2008, 11:32:17 AM
The 2nd mid course correction had prog error 1520 or error 1202 alarms occur at execute.  P00 would not set and the comp Activity light stayed on.

The state vector updates after the first one were ok.  I key in the full 5 digits in the cmc (eg 00021) for each vextor.  It is a bit clunky to work with the copy and paste.  Is it possible to push the values to excel. Or if easier pushed to a text file on  v71 execution that can then be read and  imported via an excel macro as a simple alternative. 

Welcome to the party.  :ThumbsUp432:

You win the prize. you found one of the current issues with the vAGC. The explination takes too long to go into right now (at work) There will be a big post soon that explains this and the other problem which you will find at LOI. I would suggest you DO NOT use the vAGC for the LOI burn, if you do you will see why :wink:.

I have no suggestion for making state vector updates go better other then you do not need leading zeros when entering the numbers.


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: lassombra on February 04, 2008, 01:33:27 PM
As I mentioned in another thread in development, we are going to be working soon on integrating the CMC update sheet with the MFD, this will provide a much cleaner system I think.


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on February 04, 2008, 04:04:26 PM
Thanks for the quick replies. Thanks for the EMS tip - very helpful.

I can also add that the minor display problem for the Attitude Set scroll wheel is on the Pitch wheel only when rolling to 000, it displays 350.

Cheers

The Admiral


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: Tschachim on February 05, 2008, 01:40:36 PM
I can also add that the minor display problem for the Attitude Set scroll wheel is on the Pitch wheel only when rolling to 000, it displays 350.

Yes, that's really a display problem: Only the last digit is rolled partially, the first 2 digits only show whole numbers/degrees. So if your pitch setting is 359 and you increase that number by clicking up with the right mouse button, which add 0.1 each click, the 9 begins to disappear and the 0 (of 000) begins to appear, but the first 2 digits show 35.. until you actually reach 0, so 359.9 looks almost like 350 and not almost like 000. This problem exists at every 10 step of every wheel and since it's some work to fix this rather minor problem, I don't expect a fix soon...

Cheers
Tschachim


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on February 05, 2008, 02:42:51 PM
For those following the thread, here is some more relevant information from irnenginer that relates to the issues I encountered mid flight using the vAGC

http://www.ibiblio.org/mscorbit/mscforum/index.php?topic=1566.0


Thanks Tschachim for your explanation on the scroll wheels.  It makes perfect sense and simple workaround.


The Admiral


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on February 10, 2008, 02:44:49 AM
Here's how I went on from the T+100hour mark.

The Comp Activity light was stuck on.   I found that V96, would terminate the activity.  I found that I could not load P00 without the light occurring though.  The reasons for the constant Comp Activity light are suggested in this thread.

I tried a CMC reset and tried a complete CMC shutdown and restart, but the light wouldn't clear.

I decided to postpone P23 and my final mid course correction until I was in Earth SOI.  IMFD showed me outside Earth SOI and outside Moon SOI.

Once I was in Earth SOI, I was able to enter P00 and the light problem cleared and able to do a state vector update.

I set up IMFD for the mid course correction.  I couldn't get the map IMFD to show a prograde intercept with the Earth for reentry.  It showed only as low as 158k.  On my current course, I was going to overshoot by a couple of thousand miles but at least land in the Pacific Ocean and reenter with a 6.2 degree entry angle. I decided that this would be okay on this first test run.  Better than missing the Earth entirely!  The only issue was that I would be entering 2 hours early.

All procedures up to reentry were nominal.

On reentry, all looked good by the AGC.  I was surprised by how much RCS activity there was orientating the spacecraft very quickly to entry orientation.   I was clearly going to overshoot as well.  I also realised my early arrival meant that I was going to splashdown in the dark.  Not quite ideal.


During the initial descent, the CM rotated 180 degrees a few times around its axis and there was a lot of RCS activity.  The heatshield remained pointing the right way so all seemed okay. I suspect the RCS activity was due to the overshoot.  I had programmed in the mission desired landing lat and long in the agc as the splashdown point.  I now realise imfd reentry displays entry interface lat and long.  How do i find out my new landing predicted splashdown point?

The G's maxed out and the crew died.  I thought my 6.2 degree angle would be too shallow if anything.

The rest of the descent was nominal (if I really didn't burn up).  On landing, the AGC displayed my lat on long, way off.

According to the AGC, my Lat and Lon on landing was 9.2 degrees north and 8 degrees west and 9800 miles away from the landing zone.
I knew i wasn't there.  The scenario editor pinpoints me at 8.96 degrees north, 145.99 degrees west which is in the zone of where I had been targeting.

It was hugely fun (except I killed the crew  :cry:) and will try reentry again.  It is very satisfying to have got to moon orbit and back under a full checklist.  The Apollo 8 Flightplan is very well done

The Admiral






Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: Christophe on February 10, 2008, 06:18:11 AM
Hi Admiral!
Congratulation for your flight, and thanks for sharing.

About your entry: I think you probably missed your TEI.

The TEI is usually considered as the most critical and tricky maneuver, but I remember that a procedure using IMFD 4.6 gave some good results.
Since I'm no longer familar with IMFD especially with the last IMFD 5 version, I guess it has to be updated, but anyway, here it is:



1/
On one MFD, (called further as MFD 2) open ORBIT MFD.
2/
On an other MFD (further called MFD 1) open IMFD, module BASE APPROACH
3/
on MFD 1 , IMFD:
- Set the Moon as the source (SRC button)
- Set TEJ equal to the Perigee time (PeT) displayed on orbit MFD (MFD 2)
- Set Longitude and Latitude equal to the coordinate of your landing site. You can use the historical one at first.
- Set ALT to 121.95 km. (caution! don't forget to set km and not meters!)
- Set REA to 6.50
- Set ANT to 21
- Set HINT to the historical value (from flight plan, mission report or any other doc you want) or adjust and search so as to get the mini Ov displayed on the IMFD.
4/
On MFD 2, bring up IMFD too and shared with the IMFD already displayed in MFD 1
From that step, we use "IMFD 2" to designate this IMFD and "IMFD 1" those where the Base Approach mode is running.
On IMFD 2, open the Orbit Eject program and choose the submode Base approach (don't mistake with the Base Approach prog)
5/
On IMFD 2, set and adjust TEJ to get the mini delta V
6/
On IMFD 1 (Base Approach running), Set the TEJ so as to be syncronysed with TEJ on IMFD 2
7/
IMPORTANT!
Check the EIN parameter. For the burn to be smooth and in order to avoid erratic and premature shutdown while in autoburn, this value should be less than 1.
If not, you can adjust some parameters to decrease it within 1. For example you can change the latitude of your landing site or maybe slightly change the TEJ. But don't change the other parameters and above all, don't change the following entry values: ALT, ANT, REA !
8/
That's all!
Perform your burn and welcome back home!

Note:
If you're not following the historical timeline and trajectory during lunar orbit, you may encounter some trouble with the historical landing site: wrong EIN and/or inappropriate heavy delta V (above your fuel capacity)
In this case, 2 solution:
1/
Wait for the historical TEI time and/or a proper time when the landing site is reachable again.
2/
Change the landing site.
NASA had a method for that:
It consisted in the definition of several longitude lines called as "recovery lines" where an adequate landing site could be located.
The latitude was updated in real time depending on time and lunar orbit inclination.
All the official recovery lines for a specific mission can be found on the presskit from that mission.
Presskit are available on numbers of web site. For example:
http://www.hq.nasa.gov/alsj/frame.html


If you would like to test wether that works in a way or an other with IMFD 5 I would be very pleased and I think it would be very helpfull for other people.

Regards,
Christophe


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 07, 2008, 03:06:10 PM
I'm also in the middle of running the Apollo 8 mission.  I agree with Admiral.  Everything is very well done.   :ThumbsUp432:

I have not encountered any CMC problems however, but I'm only at MET 037:xx:xx.

One question I have is regarding two different worksheets with similar names: "G&N maneuver" and "SCS Maneuver".  They both have similar procedures in them (TLI, MCC's, etc.)

1.  What is the difference between these two "sets" of procedures?

2.  It appears the G&N maneuver worksheet is not finished.  Or, at least, does not cover as many maneuvers as the "SCS Maneuver" sheet.  There is no LOI, LOC, TEI, or 3rd MCC.  Is this an error/oversite or intentional?  Perhanps the answer to question 1 will provide an answer to this question also.

Thanks

Reuben


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: pattersoncr on April 07, 2008, 06:16:47 PM
Reuben,
As I understand it, there are significant issues with the way thrust vector control (TVC) or engine gimballing works.  As a result, attitude control becomes unstable during long burns controlled by the vAGC.  See the thread Admiral linked in reply #6.


- Chuck


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: lassombra on April 07, 2008, 06:43:40 PM
The answer to the question is simple.  G&N procedures use the CMC to fly the ship through the procedure.  SCS procedures use the standby system, which is not as susceptible to the problems we currently have with the AGC due to our modeling of the TVC being incorrect.  Since the SCS is also modeled by us (and possibly also incorrectly) we are able to make sure that it works correctly.  Right now, some of the higher-duration burns are much harder to do using the CMC because of the poor TVC.  We are working on the problem, but in the meantime, if the maneuver you need to perform isn't on the G&N page, go to the SCS page.


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 07, 2008, 07:52:07 PM
Thank you Chuck and Lassobra.

I would assume that the G&N maneuvers was how it was actually done.  Are you using a PID loop to control the TVC?  I've worked with those quite a bit.  I'd be happy to lend a hand if anyone needs one. :twocents22:


Reuben


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: irnenginer on April 07, 2008, 11:53:53 PM
Currently the TVC is controlled directly by the AGC. There is some filtering in AGC software but the direct connection to the TVC angle creates an unstable condition that causes it to go out of control. Basically there is a big piece of the control loop is missing. There is a lot more to this piece and it really needs some work. If you like I will put together what I have figured out.


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: lassombra on April 08, 2008, 02:43:54 AM
Reuben, I think it'd be great to have you on the team.  I'm sure between you and irnenginer you guys can solve the problem with CMC navigation.


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on April 08, 2008, 06:26:45 AM
I'm also in the middle of running the Apollo 8 mission.  I agree with Admiral.  Everything is very well done. 

I have not encountered any CMC problems however, but I'm only at MET 037:xx:xx.


God speed Reuben.  It will be good to hear how the mission progresses.  I am interested to hear if you start getting cmc issues as you leave Earth SOI up to LOI after state vector updates.

I am just about to restart Apollo 8 and work it through fully again after my first attempt ended in the astronauts burning up on reentry.  Since my first attempt, I've been spending time learning as much as I can on apollo and the agc, especially wrt g&n. I found it to be a steep learning to go from Orbiter low earth orbit missions to apollo using the vagc  straight away as a Apollo noob.  I hope the effort and practice will pay off in a safe return this time.

This time I will take notes to scrutinize the documentation to particularly look for documentation improvements.  I also aim to hit the documented mission timelines this time to help get my TEI right .  My apogee and perigee were heights were off at the moon (my circularization burns were short in the agc) so this would have affected the time of TEI as well and my 3rd mid course correction was off. I expect CMC issues for the reasons in the link of post 6, but this time am a bit more informed to give it another go.

The Admiral


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 08, 2008, 12:49:26 PM
It would be an honor to join your team!!  :Excited432:  I certainly don't want to step on anyone's toes though.

I must confess that as a married father of two my time is a precious commodity, but I would very much like to help in any way that I can.  I think it would really help me understand what all the switches I'm toggling are really doing!

I would be very appreciative if someone would help me get started (i.e. create a working project, compiling/building, etc.).

Admiral, I will let you know how the mission progresses.

Reuben


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: lassombra on April 08, 2008, 03:59:00 PM
Reuben, I'll gladly work with you to get you started.

The first two steps are easy.  First, contact Tschachim here on the board and let him know you'd like to join the dev team.  Give him your sourceforge username (If you don't have one, register at sourceforge for one) so he can get you on the developer CVS.

Then follow the tutorial here (http://nassp.sourceforge.net/wiki/VC2005Express) to get VC++ 2005 express installed (If you want to use 2008 you can, the links are different, and the setup steps shown on that page should be irrelevant, as the 2008 installer sets up the variables and the platform sdk for you.)


Title: Re: Apoolo 8 Testing using Apollo 8 Flightplan
Post by: Tschachim on April 08, 2008, 06:26:11 PM
Hi Reuben, welcome to Project Apollo - NASSP!  :)
Just follow Lassombra's instructions and I'll add you to the developers.

... Basically there is a big piece of the control loop is missing. There is a lot more to this piece and it really needs some work. If you like I will put together what I have figured out.

That sounds like a rather major problem, yes, please tell us more. Also a scenario shortly before such a burn starts would be great, such in case you have one at hand.  :)

Cheers
Tschachim



Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 14, 2008, 03:34:06 PM
Admiral,

I have run into the same CMC issues.

Between 052:30:00 MET (after 3rd P23 of the mission ) and 060:00:00 MET I noticed I had a constant Comp Activity light come on.

The 2nd mid course correction had prog error 1520 or error 1202 alarms occur at execute.  P00 would not set and the comp Activity light stayed on.

I found this to be somewhere between hours MET 056:00:00 and MET 057:00:00.  Right around the time IMFD projected I would enter moon SOI.  Did you try to resolve the COMP ACTY problem prior to the 2nd MCC, and if not, is that why you received the 1520 and 1202 alarms?

To fix, I did a V36 CMC restart procedure.  This cleared the comp activity light error and I performed an IMU recovery.  Interestingly I was out of both Earth and Moon SOI according to IMFD so did not do a state vector update until I was in th Moon SOI well after the burn.

Where is the V36 procedure documented?  It's not in the Apollo 8 checklist.  How did you perform an IMU recovery?  Can you provide me with (or point me to) a procedure for that?

I am currently at MET 058:30:00.  I would like to resolve the COMP ACTY before the P52 alignment and 2nd MCC.

Thanks,
Reuben


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bluespace88 on April 14, 2008, 03:37:19 PM
V36 recovery is in the errors and failures tab of the mission checklist, under CMC restart..  From there, you'd go through P51 and P52 to realign the IMU, which was knocked out due to V36.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on April 14, 2008, 04:14:53 PM
Hi Reuben

I had more success with V96E later in the mission after I discovered it.  This would would terminate the comp activity light and I didn't have to realign the IMU.  You could try that.  V96 purpose is to provide a means of suspending state vector integration.  Then I went to V37E 00E successfully.

I initially didn't try to fix the comp activity light and this would have led to the 1202 and 1520 at 2nd MCC.

I got the V36 procedures where BlueDragon mentioned.  It just takes a while and by the time i left lunar orbit, V36 was proving to be ineffective.

Hope this helps

The Admiral


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bluespace88 on April 14, 2008, 04:18:14 PM
yeah, doing the entire IMU realignment takes a while.  I never tried V96, so thanks for pointing that out.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 14, 2008, 04:35:24 PM
Thank you BlueDragon and Admiral.

I reference a printed copy of the flight plan/checklists and neglected to print the "errors" page.  :oops:

If V96 suspends state vector integration, is it necessary to do a state vector update after the CMC has been reset?

Thanks,
Reuben


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bluespace88 on April 14, 2008, 04:45:07 PM
yep.  According to the manual, going to V96 does not maintain state vectors, so you would need to update them when you bring it out of suspension.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 14, 2008, 06:10:09 PM
yep.  According to the manual, going to V96 does not maintain state vectors, so you would need to update them when you bring it out of suspension.

What manual are you speaking of?


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bluespace88 on April 14, 2008, 06:11:28 PM
The Colossus 249 manual
http://www.ibiblio.org/apollo/links.html
the R-577 one.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: irnenginer on April 14, 2008, 07:32:40 PM
V96 suspends the current orbital integration cycle and goes back to POOH, which will eventually attempt another integration again. V96 does not invalidate anything like IMU alignment or the state vectors per se, though the state vectors will not get updated.

I missed the earlier email about lockup. I know exactly what that is about. I still need to commit changes to include solar position data into the AGC load(the current scenerio may also be missing an accurate lunar position as well). The AGC needs to know the position to correctly determine the state vectors when, particularly as orbiter shows, the sun and moon are dominate gravitationally.

For a while I managed to stay ahead of you guys on getting this sorta thing figured out. Now your passing me. :|

I was holding up committing until I got the TVC thing figured out. Since that will take a while I will go with what I have got, expect it in the next day or so.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 15, 2008, 01:28:08 AM
Hey irnenginer,

From where I sit, it looks as if you're still very far ahead of us.   :wink:  Let me know if I can be of help on the TVC.  After re-reading your posts, it sounds like a PID control loop would do the trick.

Thanks for the link to the AGC manual, BlueDragon.  That is by far the most comprehensive source I've seen!

Reuben



Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on April 15, 2008, 03:43:55 AM
Yeah, the manual is like the nuts poker hand for the AGC.  You just can't beat it.

It will be interesting to see if you can do the state vector update after v96, Reuben, pre and post irnenginer's commit to see if this affects the comp activity light before you get to 2nd MCC.

The Admiral


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: irnenginer on April 16, 2008, 12:22:29 AM
For some reason CVS is not letting me commit the changes to Apollo 8 to add the solar positioning. But since you are in the middle of the mission anyway I will add a cheat to add in to your scenario here as well so you do not have to start over. Add in the following
Code:
  EMEM2132 750
  EMEM2133 17451
  EMEM2134 60235
  EMEM2135 24074
  EMEM2136 71143
  EMEM2137 15361
  EMEM2140 22712
  EMEM2141 32350
  EMEM2142 1013
  EMEM2143 10220
  EMEM2144 343
  EMEM2145 11014
  EMEM2146 550
  EMEM2147 4340 

This should get rid of that pesky COMP ACTY lockup.  :ThumbsUp432:

Reuben,

Take a look at section 6.10 of that R-577. Section 6.10 contains a block diagram (page 6-66 :evil:) of the SPS actuators.  As it is shown there it is more complex then a PID could model. I do think we may be able to use a PID to get close enough to work. I am working on simulating this model, and we could adapt something from that.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: Tschachim on April 16, 2008, 08:29:15 AM
Hi irnenginer,

what problems did you encounter with CVS? Do you want me to commit these changes for you?
And a little bit OT, do we get a solar position for Apollo 7, too?  :)

Cheers
Tschachim


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: lassombra on April 16, 2008, 12:19:16 PM
Yeah, I wants me solar position  :Excited432:

Realistically though, it's nice that the AGC now knows where the sun is.  irnenginer, you are amazing...  Keep it up!


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 16, 2008, 12:36:33 PM
irnenginer,

Thanks for the scenario data.  I'll give that a try soon.

After looking at the block diagram you mentioned, I don't believe it's coincidental that the page number is 6-66.  WOW!!  :shock:

I'm not sure I understand what all the grpahical symbols mean.  For example the circle with the 'X' or the '+' with a slash that has 2 horizontal ends.

In addition, it doesn't appear that all the mathmatical symbols are defined.  I don't see a definition for TS (Tau).


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: irnenginer on April 16, 2008, 03:46:30 PM

what problems did you encounter with CVS? Do you want me to commit these changes for you?
And a little bit OT, do we get a solar position for Apollo 7, too?  :)

It was not accepting my password. I was going to try again before I got worked up about it.
We can also get A7 solar data as well. I have it calculated and I just need to enter it in as well.

For example the circle with the 'X' or the '+' with a slash that has 2 horizontal ends.

In addition, it doesn't appear that all the mathmatical symbols are defined.  I don't see a definition for TS (Tau).


The circle(X) blocks are summing nodes that either add or subtract based on the symbol of the inputs. The second is a limiter such that when a input goes above a limit the output holds to the limit.

I think TS is actually T5
:)


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on April 16, 2008, 04:15:35 PM
Code:
  EMEM2132 750
  EMEM2133 17451
  EMEM2134 60235
  EMEM2135 24074
  EMEM2136 71143
  EMEM2137 15361
  EMEM2140 22712
  EMEM2141 32350
  EMEM2142 1013
  EMEM2143 10220
  EMEM2144 343
  EMEM2145 11014
  EMEM2146 550
  EMEM2147 4340 

This should get rid of that pesky COMP ACTY lockup.  :ThumbsUp432:


I just tried this at 59 hours on a quick save that had the stuck light.  Within 44 seconds, poof, the light went out.

It worked!  Thanks irnenginer.

How did you work that out?

I missed the earlier email about lockup. I know exactly what that is about. I still need to commit changes to include solar position data into the AGC load(the current scenerio may also be missing an accurate lunar position as well).

I have stuck lights later in the mission so if you have an accurate lunar position data, I could check it in later quicksaves too

Hope this holds for you Reuben for the rest of the mission.



The Admiral


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 16, 2008, 04:23:26 PM
So, irnenginer, are you are able to model the entire diagram then?  If so, I'd say you're on your way to a solution.   :ThumbsUp432:

Sadly, I'm not very versed in mechanical control theory.  I don't think I can be much help after all.   :sorry345:

Good Luck!


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: irnenginer on April 16, 2008, 10:19:33 PM
How did you work that out?

I do have a Wiki item for the solar stuff but it does not have much in it yet.

http://nassp.sourceforge.net/wiki/Solar_Ephemeris

Actually the Solar Ephemeris is a layup compared to the lunar. Which I did check and found that it is correct in Apollo 8 so you should be good to go.

So, irnenginer, are you are able to model the entire diagram then?  If so, I'd say you're on your way to a solution.   :ThumbsUp432:

Sadly, I'm not very versed in mechanical control theory.  I don't think I can be much help after all.   :sorry345:

Good Luck!

In theory I should be able to get a model to work, but as they say, in theory communism works! :D In reality I was never very good at control systems. But I did pass the class.  :D


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: Tschachim on April 17, 2008, 04:53:16 AM
It was not accepting my password. I was going to try again before I got worked up about it.

I found this on the SourceForge status site:

Quote from: SourceForge
(  2008-03-07 05:25:00 - Project CVS Service, Project Shell Service, Project Subversion (SVN) Service, SourceForge.net Web Site  )   On 2008-03-06, during a routine security audit, SourceForge.net staff identified a deficiency in systems data control. We are unaware of any exploitation of this data, which was present in encrypted form. In addition to removing the data, as a preventative measure we have also forced password changes for all SourceForge.net user accounts.

( 2008-03-06 14:23:47 - SourceForge.net Web Site )   In support of improved security, all SourceForge.net user passwords have been expired and must be changed upon next login. CVS, Subversion and Shell users will need to login to the site to change their password before they will be able to access these services.

so perhaps you need to login on the SourceForge site at first and change your password.

We can also get A7 solar data as well. I have it calculated and I just need to enter it in as well.

Great news, thanks a lot!  :ThumbsUp432:

Cheers
Tschachim


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: lassombra on April 17, 2008, 02:56:29 PM
That doesn't affect me because I use an ssh key to log in :)


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 17, 2008, 05:19:54 PM
I added the EMEM values to my scenario and just as Admiral stated, the lock up disappeared within 30 seconds.  I was able to do my 2nd MCC with no problems.  :)

However, I am now at MET 065:16:00 and the lock up has resumed.  I have since save the scenario a couple of times and verified that the most recent scenario still contains those EMEM values.  Any ideas?



Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bluespace88 on April 17, 2008, 10:00:37 PM
Nope.  I had the same problem.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: Admiral on April 18, 2008, 03:38:16 AM
Did you try a state vector update?  If you had done a V96 mentioned in earlier posts, then you might have to try another manual state vector update again.  My  :twocents22:


The Admiral


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: lassombra on April 18, 2008, 04:07:35 AM
I believe it's something like 24 hours between required state vectors now.  There's a post about this somewhere...  The vAGC now knows what it needs to know to know when to force a SV update.  Though, if I remember, that should only cause a prog alarm, and only when doing something that requires the state vector.  So... I don't think that can cause the freeze up.

Instead, it sounds like messed up lunar ephemeris data.  If you are now in the lunar SOI, that is likely the new problem.

just my  :twocents22:


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bluespace88 on April 18, 2008, 06:58:02 AM
well, I went back and redid the state vectors.  I might have messed up a number somewhere when punching it in, as I'm now at 66 hours within the moon soi and no comp acty problems.

Need to fix the state vector stuff to let you choose between moon or earth soi when in the sun's soi.

EDIT: I'm now in a circular lunar orbit, and the computer has given me no problems at all.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: rwitham on April 18, 2008, 12:01:05 PM
After my last post, but before any replies, I tried V96 and that did stop the lock up.  I did not immediately to a SV update as I was scheduled to do one shortly there after.  Once I terminated the PTC at PeT=3.800k I did the SV update and things were OK.

I performed the LOI according to the SCS maneuvers of the flight plan but did not stay in orbit!  Before the burn took place I made a visual inspection of my orientation wrt to the moon and the CSM was pointed in the direction of travel.  Shouldn't I have been facing SPS-engine-bell-first for the burn to place me into orbit?

After the burn I could clearly see that I was not in orbit.  IMFD confirmed this.  I reloaded the scenario back to PeT=3.800k and tried the whole thing again with the same results.  Any clues as to why the IMFD BV screen is telling me to point the ship the wrong way?  I have attached the scenario at PeT=-1.400k after the ship has been oriented correctly (according to IMFD).

I am still running this scenario on the Jan 16 module release and not the latest in CVS.  irnenginer, do you recommend I use the new Solar Ephemeris solution in CVS?

I'm beginning to think that I should restart the mission over using the lastest in CVS as I am not happy with my course maneuvers all the way back to TLI.




Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: lassombra on April 18, 2008, 12:57:43 PM
Well, I haven't had a chance to boot up that scn, but what MFD mode are you using?


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bluespace88 on April 18, 2008, 01:23:35 PM
I see your problem.  When doing dVf, you want to go Negative for a retrograde burn,  Right now, you're burning positive dVf, which results in a prograde burn, so you're not actually slowing down, but speeding up.  Just set it to 0 and then adjust it by lowering the value.  Should get around -1.004k for dVf.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: irnenginer on April 18, 2008, 07:18:46 PM
FYI I just committed the Apollo 8 changes for solar data. Resetting my password did the trick


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bluespace88 on April 19, 2008, 01:43:43 PM
just came back to Earth, all safe and sound.  Had an issue during reentry when the gimbals locked, but luckily that was very late in reentry just before hitting 50,000 ft.  Though, I had to manually release the chutes and go to V16N67.  The values in the AGC for latitude and longitude were also off by quite a bit, almost 180 degrees for longitude.  Other than that, landing was smooth and there were no other major problems besides the gimbals and agc data.


Title: Re: Apollo 8 Testing using Apollo 8 Flightplan
Post by: bertog on April 20, 2008, 02:50:38 PM
Hi all,

I'm flying the 8 and everything is fine and smooth. I'm arrived near the MET+20.

Two question: I've read in the Apollo 12 Fligh Plan that soon after the insertion they have setup an LVLH - head down attitude following an orbital rate and i think this attitude is the same for all the apollo flight. There's some way to setup this attitude in the current release ?

In the same Flight Plan before any P52 there's a "Manovre to 52 Attitude". Could some one tell me what is a correct P52 attitude and how yo set it up ?