thermocalc
Active member
Hi to all.
After 1 month I completed Apollo 8 from Lift-off to Splashdown “almost” without a glitch using Orbiter2016 with MOON high resolution textures and NASSP v8 version 1749 (I know I know, I should use Orbiter Beta, but reading others in the forum I “think” to have understood that Apollo 7 and 8 which don’t have “docked vessels” can still be flown “successfully” even in Orbiter 2016, at least I can take advantages of the MOON and EARTH Apollo landmarks for making P22/P23…), with max x20 time acceleration during the long coast phases…and contrary to last year, when I used Apollo 8 in NASSP v7 on Orbiter 2010P1 this time the simulation was relatively smoothly, I never had AGC issues while running time accelerations and all MCC’s messages (almost) came up more or less around the checklist times, so I guess in this year of further development the sim got more robust and stable. A HUGE THANKS to all developers to achieve this target.
I said “almost” as I run into some “inconsistencies” which I would like to share with you, to understand what I did wrong (if it was my fault) or maybe can be traced back to computer issues due to low frame rates when using Orbiter2016.
Q1.
At GET 090:01:20 I got the ENTRY REFSMMAT uplink (090:00:15 according checklist time) and at time 090:05:00 I changed the REFSMMAT from LOI-2 to ENTRY doing P52-option 1. The next P52-option 3 went smoothly (see file “P52 series” for a bunch of them and values I got in N93).
At GET 102:46:50 I got the MCC-5 uplink with LM SV update, target load and ENTRY REFSMMAT (I guess “ENTRY REFSMMAT” in yellow text was just a “note” in the checklist to tell that for MCC-5 the burn attitude is referred to the ENTRY REFSMMAT…changed time back ago…don’t know/think that an ENTRY REFSMMAT (the rotational matrix elements so to speak, was indeed sent up again during the uplink, and if so why there was another P52-preferred to do?). Anyway, I completed the uplink, but after that when doing P52-option 3 at 102:52:00 the optics were far off from the target stars (see “optics not aligned” photo). Anyway I press on, I centered manually the stars and complete P52 (and as you can see from “P52 series” at that time on R2 N93 I got a huge angle difference), but after finishing this P52 a made another P52-optino 3 at time 103:00:00 and everything was correct again…(see again “P52 series” photo).
When the time came for making MCC-5 everything went well, the SXT STAR was there in the SXT at the correct time and Shaft/Trunnion angles as in the burn PAD…so I guess everything went well (indeed I splashdown “somehow”).
So the question is why after the MCC-5 uplink I got the optics out of alignment?
Was it supposed to work like that? Including the weird stars alignment to be manually corrected?
Or was I just “lucky” to be able to complete the mission?
If you are interested I will attach the scenario just few minutes before to get the MCC-5 PAD and after uplink, when doing P52 the stars should not be centered.
Q2
After receiving the final entry pad at 146:03:25 GET time (145:55:00 according checklist) I was supposed to see the Earth horizon pitching up to 268 degree at time 146:31:25, with +/- 5 degree tolerance, but even if I was at that attitude the Earth was not there in the COAS CDR window (again, if you want ti can upload the scenario at this time). Why? Was I in incorrect attitude? Or just the Earth Horizont was not visible as “night time” for A8 mission?
Anyway upon CM/SM separation by putting the CM at the PAD entry attitude at Pitch 152 (R=0, Y=0) I managed to survive and land…so I guess I was not in a too bad wrong attitude; OR is this event to be traced back to the weird issues I experienced at time 102:52:00 when I got that strange optical issue? Did I have indeed a wrong Entry REFSMMAT at all times ???
Q3
When making P61 at some time in the entry checklist it is written to read from the GNC the calculated values form some items to be compared with the ENTRY PAD values, and based on them decide for “PGNCS go / no-go”.
How should I know how to decide if go / no-go for an automatic CMC reentry? How much are the allowable tolerances between the ENTRY PAD and P61 displayed values?
For example I got:
N61 (lat +7.44, long -164.96, hds -1) -> entry PAD was (lat +7.44, long -164.96, lift vector up->which I guess it is “heads down -1).
N60 (Gmax +6.97, V pred 36214, gamma -6.55) -> entry PAD (Gmax 6.5, Vpred 36226, gamma -6.49)
N63 (RTGO 12858, VIO 36293, TEE -20 32) -> entry PAD (RTGO 1260.6 set in EMS, VIO 36315 set in EMS)
After N63 should I manually modify the EMS PAD values entered before to these new values displayed on N63?
Also the predicted time of EI 146:48:53 was slightly off from the PAD value of 146:48:25.
Should I be worried for these “deviations”?
Q4
In the ENTRY PAD the target, splashdown coordinates were +7.44 LAT / -164.96 LONG.
Upon splashdown I got in F16 67: R1 -00024 (I hit the target 2.4 NM short, if my interpretation is correct), R2 +00741 (+7.41 LAT) and R3 -16495 (164.95 LONG) … I guess not so bad.
BUT in the Apollo by Numbers I saw that the actual splashdown coordinates were +8.10 LAT and -165.00 LONG … so if the MCC “knows” where I am heading at all times, why he scrubbed MCC-6 and MCC-7 if he “predicted” a target splashdown in the ENTRY PAD which was not the historical correct one? Or in the MCC calculations the final target splashdown coordinates don’t enter into the actual calculations to be done for up linking a burn vector and TIG?
But anyway, if I got these numbers should I consider my mission a success or a failure?
Thanks for reading me.
Best regards.
After 1 month I completed Apollo 8 from Lift-off to Splashdown “almost” without a glitch using Orbiter2016 with MOON high resolution textures and NASSP v8 version 1749 (I know I know, I should use Orbiter Beta, but reading others in the forum I “think” to have understood that Apollo 7 and 8 which don’t have “docked vessels” can still be flown “successfully” even in Orbiter 2016, at least I can take advantages of the MOON and EARTH Apollo landmarks for making P22/P23…), with max x20 time acceleration during the long coast phases…and contrary to last year, when I used Apollo 8 in NASSP v7 on Orbiter 2010P1 this time the simulation was relatively smoothly, I never had AGC issues while running time accelerations and all MCC’s messages (almost) came up more or less around the checklist times, so I guess in this year of further development the sim got more robust and stable. A HUGE THANKS to all developers to achieve this target.
I said “almost” as I run into some “inconsistencies” which I would like to share with you, to understand what I did wrong (if it was my fault) or maybe can be traced back to computer issues due to low frame rates when using Orbiter2016.
Q1.
At GET 090:01:20 I got the ENTRY REFSMMAT uplink (090:00:15 according checklist time) and at time 090:05:00 I changed the REFSMMAT from LOI-2 to ENTRY doing P52-option 1. The next P52-option 3 went smoothly (see file “P52 series” for a bunch of them and values I got in N93).
At GET 102:46:50 I got the MCC-5 uplink with LM SV update, target load and ENTRY REFSMMAT (I guess “ENTRY REFSMMAT” in yellow text was just a “note” in the checklist to tell that for MCC-5 the burn attitude is referred to the ENTRY REFSMMAT…changed time back ago…don’t know/think that an ENTRY REFSMMAT (the rotational matrix elements so to speak, was indeed sent up again during the uplink, and if so why there was another P52-preferred to do?). Anyway, I completed the uplink, but after that when doing P52-option 3 at 102:52:00 the optics were far off from the target stars (see “optics not aligned” photo). Anyway I press on, I centered manually the stars and complete P52 (and as you can see from “P52 series” at that time on R2 N93 I got a huge angle difference), but after finishing this P52 a made another P52-optino 3 at time 103:00:00 and everything was correct again…(see again “P52 series” photo).
When the time came for making MCC-5 everything went well, the SXT STAR was there in the SXT at the correct time and Shaft/Trunnion angles as in the burn PAD…so I guess everything went well (indeed I splashdown “somehow”).
So the question is why after the MCC-5 uplink I got the optics out of alignment?
Was it supposed to work like that? Including the weird stars alignment to be manually corrected?
Or was I just “lucky” to be able to complete the mission?
If you are interested I will attach the scenario just few minutes before to get the MCC-5 PAD and after uplink, when doing P52 the stars should not be centered.
Q2
After receiving the final entry pad at 146:03:25 GET time (145:55:00 according checklist) I was supposed to see the Earth horizon pitching up to 268 degree at time 146:31:25, with +/- 5 degree tolerance, but even if I was at that attitude the Earth was not there in the COAS CDR window (again, if you want ti can upload the scenario at this time). Why? Was I in incorrect attitude? Or just the Earth Horizont was not visible as “night time” for A8 mission?
Anyway upon CM/SM separation by putting the CM at the PAD entry attitude at Pitch 152 (R=0, Y=0) I managed to survive and land…so I guess I was not in a too bad wrong attitude; OR is this event to be traced back to the weird issues I experienced at time 102:52:00 when I got that strange optical issue? Did I have indeed a wrong Entry REFSMMAT at all times ???
Q3
When making P61 at some time in the entry checklist it is written to read from the GNC the calculated values form some items to be compared with the ENTRY PAD values, and based on them decide for “PGNCS go / no-go”.
How should I know how to decide if go / no-go for an automatic CMC reentry? How much are the allowable tolerances between the ENTRY PAD and P61 displayed values?
For example I got:
N61 (lat +7.44, long -164.96, hds -1) -> entry PAD was (lat +7.44, long -164.96, lift vector up->which I guess it is “heads down -1).
N60 (Gmax +6.97, V pred 36214, gamma -6.55) -> entry PAD (Gmax 6.5, Vpred 36226, gamma -6.49)
N63 (RTGO 12858, VIO 36293, TEE -20 32) -> entry PAD (RTGO 1260.6 set in EMS, VIO 36315 set in EMS)
After N63 should I manually modify the EMS PAD values entered before to these new values displayed on N63?
Also the predicted time of EI 146:48:53 was slightly off from the PAD value of 146:48:25.
Should I be worried for these “deviations”?
Q4
In the ENTRY PAD the target, splashdown coordinates were +7.44 LAT / -164.96 LONG.
Upon splashdown I got in F16 67: R1 -00024 (I hit the target 2.4 NM short, if my interpretation is correct), R2 +00741 (+7.41 LAT) and R3 -16495 (164.95 LONG) … I guess not so bad.
BUT in the Apollo by Numbers I saw that the actual splashdown coordinates were +8.10 LAT and -165.00 LONG … so if the MCC “knows” where I am heading at all times, why he scrubbed MCC-6 and MCC-7 if he “predicted” a target splashdown in the ENTRY PAD which was not the historical correct one? Or in the MCC calculations the final target splashdown coordinates don’t enter into the actual calculations to be done for up linking a burn vector and TIG?
But anyway, if I got these numbers should I consider my mission a success or a failure?
Thanks for reading me.
Best regards.