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Author Topic: Apollo 8 (vAGC) Synopsis, Flightplan and Procedures  (Read 24203 times)
jc121081
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« on: January 06, 2008, 10:00:18 PM »

Hello all!

After a good bit of work and testing its composition, the preliminary version of the Apollo 8 (vAGC scenario) Flightplan is now committed to CVS. I'll include some rough details for its use and a detailed report of my progress in testing the mission below.

The new Flightplan file is in much the same manner as before, but with some greatly varied procedures over the previous that work quite well and can be flown almost exactly to historic time references if followed correctly. In this version, I included the "SCS" procedures for the maneuvers, and will update the file to include the G&N (vAGC) assisted procedures once a few more issues (whom irnenginer was incredibly helpful in helping me to identify) are resolved. I did include the "G&N maneuvers" tab in the file so that you may be able to perform PTC, which I might add works quite well in this mission. The attitude for each PTC maneuver is included in the flightplan file and match the real historical attitudes used.

In the scenario's current state, you may also run into a few random and consistent COMP ACTY problems on the DSKY as you near the moon. If this should happen, I included a relatively quick procedure under the "Errors and Failures" tab which will help you clear the light and restart/realign the guidance platform.

Here is a detailed (perhaps a little too "overdetailed") evaluation of my experience in our Apollo 8 scenario:

SPS propellant remaining:
MCC1: 99.2%
MCC2: N/A (translational thrust)
LOI: 57.6%
LOC: 56.1%
TEI: 20.7%
MCC3: 18.3%

Velocities:
MCC1: 50.2 ft/sec (15.31 m/sec)
MCC2: 4.6 ft/sec (1.39 m/sec)
LOI: 3191.3 ft/sec (972.7 m/sec)
LOC: 138.3 ft/sec (42.15 m/sec)
TEI: 3890.0 ft/sec (1185.68 m/sec)
MCC3: 264.2 ft/sec (80.54 m/sec)

H2 QTY remaining at CM/SM sep: 45%
O2 QTY remaining at CM/SM sep: 54%
SM RCS QTY remainging at CM/SM sep: Quad A&D - 90lbs
SM RCS QTY remainging at CM/SM sep: Quad B&C - 85lbs

Re-Entry Trajectory:
REA: 6.40
Vacuum PeA: 20.9nm (38.68km)
Velocity at EI: 36,187.7 ft/sec (11,030 m/sec)
Max G's: 6.39G
EMS: Functioned sufficiently, scroll worked smoothly. Included procedure on its use. Thanks Swatch for this great feature! Thumbs Up

I'm interrested on hearing everyones' results following the new Flightplan. Enjoy! Happy

Regards,
jc121081


* Lunar Orbit.JPG (28.33 KB, 791x575 - viewed 1121 times.)
« Last Edit: January 06, 2008, 10:02:48 PM by jc121081 » Logged
Swatch
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jasonims
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« Reply #1 on: January 07, 2008, 05:26:34 PM »

This is great news!

Glad to hear the EMS worked sufficiently well.

I'm going to put a bit of code in that dumps the EMS scroll values, I think.   That way we can compare data a little better.
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My Project Apollo Work:
CM Visual
 -VC (~75% complete: texture work beginning again; mesh-78%; texture-70%)
Propulsion Particle Improvements (Focused on S1B right now, BETA 1.0 has been commited)
New Docking Method (~50% complete: research complete; coding partially completed, testing not underway)

Future Work:  (if it's here, it's deemed unnecessary to upcoming release)

Older Work:  (if it's here, it's fair game to whoever wants to improve)
EMS Implementation (committed: minor flaws, but groundwork is there, needs extensive testing)
EMS scrolls (committed: not refined, but usable)
SM Visual (committed: mesh-finished, texture-60%; possibly revisited in future)
J2 Texture (commited: room for improvement)
LRV (committed: mesh-finished, texture-90%; in future a ground up rebuild may be in order, but not on my plans)
Mooncat
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« Reply #2 on: January 08, 2008, 05:51:10 AM »

The EMS works well for me now, I'm not sure what I was doing wrong before but following your procedures has it scrolling away happily. Although I'm not sure the other astronauts were happy with my hamfisted re-entry piloting  Very Happy
Great piece of work  JC Happy
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jc121081
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« Reply #3 on: January 08, 2008, 08:51:28 PM »

Thank you very much!

I just committed updates on both the Apollo 7 & 8 Flightplan files. I included the EMS procedure on Apollo 7 as well as a couple of other changes to make it more user friendly. Also included is a new "Help" tab, summarizing the mission profile and explaining some functions to the more novice user.

As for the Apollo 8 Flightplan, I included a procedure for P52 option 2 for Entry REFSMMAT, which I'm glad to report works very well from as far out as the 3rd Midcourse Correction (FDAI ball Roll & Yaw were 0 at EI). This will be very beneficial to avoid gimbal lock during entry.

I'm tossing around a couple of ideas in my head that I'm thinking of including, but figured I'd get some opinions on them first. Eventually I'll include procedures for lunar landmark sighting and future landing point marking, but I was thinking about including a section simulating the lunar landmark photography taken during the mission. The "photo" (of course taken using your "Prt Scr" key) could be taken after the CSM was aligned so that the landmark could be sufficiently viewed outside of the docking window.

The other thing I've been thinking about is replacing the current P30 procedures with P31. Although right now the Lambert aim point will have to be calculated and then V71'd through use of the CMC update sheet, it will not only be more historically accurate but will get us used to having the values previously stored in the vAGC, good practice for when MCC is able to uplink PAD burn data (once implemented).

Comments and suggestions are always welcome.

Regards,
jc121081
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FordPrefect
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« Reply #4 on: January 09, 2008, 07:59:57 PM »

jc, I had a glance at all the files. Your work is outstanding!  Thumbs Up Thumbs Up

I hope I find the time to dive into all this soon, it looks very detailed and highly interesting.
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My Project Apollo work in progress:
* New detailed Lunar Module Ascent stage with virtual cockpit (VC currently planned as eye candy only) 18 % done

My Project Apollo work to be continued:
* new Service Module SPS engine bell
* various Saturn V textures, exhaust textures
* SIM Bay for the SM


My long-term plans are to create a:
* New detailed Lunar Module descent stage (eventually models of all flown LM's)
* New F-1 engines for the S-1C stage showing the foil (batting) insulation
* New LUT and launch pad (if nobody else does it)
Christophe
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« Reply #5 on: January 10, 2008, 02:38:31 PM »

The other thing I've been thinking about is replacing the current P30 procedures with P31. Although right now the Lambert aim point will have to be calculated and then V71'd through use of the CMC update sheet, it will not only be more historically accurate but will get us used to having the values previously stored in the vAGC, good practice for when MCC is able to uplink PAD burn data (once implemented).

The use of P31 requires the computation of the so called "cross-product steering", symbolyzed by the letter "c".
For P30 c=0 which is much more easy ( Very Happy) but for P31 it has to be calculated.
GSOP doesn't give the math but simply says that c was computed by the ground.

i randomly found this doc last week, where the method is described. It's a pdf file; scroll down to page 153.
Since that could help you I attached it to this post.

* 2_4_9_mit_role.pdf (7872.59 KB - downloaded 611 times.)
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jc121081
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« Reply #6 on: January 10, 2008, 05:23:51 PM »

The use of P31 requires the computation of the so called "cross-product steering", symbolyzed by the letter "c".
For P30 c=0 which is much more easy ( Very Happy) but for P31 it has to be calculated.
GSOP doesn't give the math but simply says that c was computed by the ground.

i randomly found this doc last week, where the method is described. It's a pdf file; scroll down to page 153.
Since that could help you I attached it to this post.

An interresting and very informative document you've found there. I'll take some time studying this. Thanks Christophe! Thumbs Up
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jc121081
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« Reply #7 on: January 12, 2008, 11:03:11 AM »

Updated both Flightplan files to include P51 and rearranged the procedures under the "alignment" tab. Also added an "about" tab to the Apollo 8 Flightplan summarizing the mission, as well as a couple of other small improvements to both files. The next update will likely involve G&N assisted procedues and several other additions, but will involve some testing before I commit it.

Regards,
jc121081
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jc121081
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« Reply #8 on: January 13, 2008, 01:03:08 PM »

Amidst some other improvements, I also added periodic System Checks to the flightplan files. Included (under the "Systems" tab) is a field where you may record the variables as indicated by the indicators. This little feature will allow you to note and compare spacecraft performance at different points in the mission as well as make it easier to evaluate technical specifics of each of the CSM's systems following the flight.

Regards,
jc121081
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Mooncat
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« Reply #9 on: January 13, 2008, 03:02:38 PM »

It just gets better and better Thumbs Up
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lauderj
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« Reply #10 on: January 16, 2008, 08:35:52 AM »

jc

Just wanted to tell you how much I appreciate you work with these flight plan files. I was having a bit of a difficult time working with IMFD and your procedures help considerably. However, I did have one particular issue last night when I was attempting to do the first Apollo 8 mid-course correction. Surlely I must have done something wrong but not sure what I did. I have two specific issues:

1.) When I pushed the "Thrust ON" button, nothing happened and then got a master alarm indicating that there was no SPS pressure and the engine did not lite. I immediately turned on the line heaters and got a good ignition. My SPS propellent temp was above 75 degs so I had turned them off ... so not sure what exactly happened here.

2.) The SPS did not turn itself off after the EMS delta v counter reached zero. I had to manually turn off the burn.

FYI ... I am running my own build based on a CVS update of 1/15/08.

Also, another question regarding setting of the IMFD GET parameters for TLI. I started the scenario from the - 3 hr mark so, as you indicated in your instructions, I added the 3 hrs time to the GET parameters in the IMFD. So the GET of the burn reflected 5:50. I expected the autoburn to occur then really at 2:50 per the flight plant but it indeed did not occur until the 5:50 mark. So I am a bit confused relative to if this "3 hour adjustment" is really required. I seem to recall from some prior threads that someone seemed to fix that problem by initializing the GET to zero at launch in the "Crawler" but not totally sure if I understood that correctly.

If you have any idea of what I might have done wrong in the MCC procedure and could comment on the "3 hr adjustment" rule, I would be much obliged.

Again JC, thanks for you great work with these flight plan files

Jerry
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jc121081
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« Reply #11 on: January 16, 2008, 01:01:09 PM »

1.) When I pushed the "Thrust ON" button, nothing happened and then got a master alarm indicating that there was no SPS pressure and the engine did not lite. I immediately turned on the line heaters and got a good ignition. My SPS propellent temp was above 75 degs so I had turned them off ... so not sure what exactly happened here.

First off, thank you for your kind words and for testing the flightplan. Happy The problem you mentioned above is something I've never experienced before, but we could probably get to the root of it. First off, (if you are using the most current version of the Ap8 flightplan), you should notice the "systems checks" added now. I'm not sure if you may have recorded the SPS tank pressures (He, N2A & N2B), but I was wondering if you could give me an idea of what they read. Did you happen to receive a "SPS" C/W light, by chance?

2.) The SPS did not turn itself off after the EMS delta v counter reached zero. I had to manually turn off the burn.

Hmmm, sounds to me like you may have missed a step there, but I suppose it could be something else. But that's okay, because it seems that you caught the problem. Did you happen to turn the EMS FUNC dial to dV SET prior to setting the Velocity Counter, then the EMS to MODE/NORMAL and then the FUNC to dV? This could be the only possible resolution to that problem that I can think of. The SPS should cut off once the Velocity Counter reaches 0.

Also, another question regarding setting of the IMFD GET parameters for TLI. I started the scenario from the - 3 hr mark so, as you indicated in your instructions, I added the 3 hrs time to the GET parameters in the IMFD. So the GET of the burn reflected 5:50. I expected the autoburn to occur then really at 2:50 per the flight plant but it indeed did not occur until the 5:50 mark. So I am a bit confused relative to if this "3 hour adjustment" is really required. I seem to recall from some prior threads that someone seemed to fix that problem by initializing the GET to zero at launch in the "Crawler" but not totally sure if I understood that correctly.

Sorry about that, I wrote some of the early stages of the flightplan before a few changes were committed and I'll be sure to remove that from the flightplan. Thanks for pointing that out. The most tricky thing about maintaining these files is that they remain compliant with new development, something I try to focus on alot but unfortunately, as you noticed, I may miss one every once in a while.

On the flip side, I'm testing the whole scenario from scratch and will be including more historically accurate trajectories to aim for as well as full procedures for PGNCS assisted maneuvers (again, many thanks to irnenginer for his hard work on the Apollo 8 padloads). I'm also weighing the possibility of simply removing the "SCS" style maneuvers from the flightplan, as they will essentially be unnecessary one the new procedures are in (unless more random failures are included that involve the vAGC in the future). Expect to hear something in a few days.

Regards,
jc121081
« Last Edit: January 16, 2008, 01:04:47 PM by jc121081 » Logged
lauderj
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« Reply #12 on: January 16, 2008, 02:00:41 PM »

JC

Regarding the SPS tank pressure, I did indeed get a C/W light and alarm. Also, perhaps an hour or so before the MCC I did indeed note SPS pressures and temps. My temp was reading zero and pressures where 2800 with N2A and N2B and 3800 for He. If I remember correctly, when I noted the zero temp, I turned on the line heater switches and by the time I went to do check the temp prior to MCC, I noticed that the temp was full scale high so I turned off the heaters. This may have been 30 to 40 minutes before the actual burn ... not totally sure. I wll check this more carefully durning the next MCC.

Regarding the EMS, deltaV thing ... reading your note I know what I did wrong. Instead of moving the EMS FUNC knob to dvSet, I moved it to either VoSet or RNG SET, not sure which one. Obviously, that was the problem.

With the speed that changes occur with this beta (good thing) I can understand how difficult it is to keep up the written docs.

Again, thanks for the feedback and your efforts

Jerry
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Tschachim
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« Reply #13 on: January 16, 2008, 03:48:58 PM »

Hi lauderj,

1.) When I pushed the "Thrust ON" button, nothing happened and then got a master alarm indicating that there was no SPS pressure and the engine did not lite. I immediately turned on the line heaters and got a good ignition. My SPS propellent temp was above 75 degs so I had turned them off ... so not sure what exactly happened here.

That's strange, neither the line heaters nor the propellant temperature affect the SPS burn currently. From the propellant pressure drop it looks like you closed the SPS Helium valves and switched them to ON or AUTO again before it worked, but I'd need a scenario shortly before the burn to tell definitely. More infos are here: http://nassp.sf.net/wiki/SPS

Cheers
Tschachim
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lauderj
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« Reply #14 on: January 16, 2008, 04:30:54 PM »

Tschachim,

Thank you for the tip. I am obviously a little confused over the manual operation of the SPS but the Wiki SPS page has really help out explaining this (and the EMS operation). I actually found the link at http://nassp.sourceforge.net/wiki/Service_Propulsion_System. The nassp.sf link seemed dead. In any event, I need to read over these more carefully.

Now if I could only figure out why my suit temp tends to go full scale high after awhile in the spacecraft

Thank you

Jerry
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