Apollo 9 - orbiter version 1771

rcflyinghokie

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Hi,

Sorry for my late reply but I was occupied in other things … I did again some testing, about my previous Q1 and Q2, and I tried to point out what I am doing and observing; inside the 2 zip files some sceneries and some pdf in which I described in details the problems I faced for your further analysis.

Thanks as usual.
Kind regards.

FYI: during P22 on day 7 I noticed that I can maintain LVLH heads up attitude (by SRF MFD) with a -ve 0.075 deg/s pitch rate (manually created by IMPULSE mode) and the FDAI ORDEAL at 0-0-0 ... but this time there was a P52 "nominal" before, indeed also FDAI 1 (inertial) was showing 0-0-0 at time of start of the orb rate ... does this observation may help to shed light on my issues on day 6, when the REFSMMAT was different? (and the FDAI 2 GDC driven was aligned to the FDAI 1 INERTIAL driven with a different REFSMMAT) ... just guessing....maybe uncorrelated facts...anyway for P22 it works, no issues there :)
Regarding the P51's the star pair can play a role. I tried it with a few pairs and got almost perfect angles each time, even using each of the pairs you posted so I am thinking this is user error with marking somehow.

For the ORDEAL, that actually is the "correct" behavior for a retrograde attitude/REFSMMAT. Since the ORDEAL can only rotate one way, it rotates "away" from your position since you are using a retrograde DAP rate. You will notice your spacecraft stays in an orb rate attitude, but the ball rotates away from it and this behavior was seen on the actual mission as well.
 

rcflyinghokie

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You gotta null your rates real carefully before P51, else the huge deltas. I just use the killrot button in PAMFD for P51, works every time.
You dont need killrot, you can null them manually or with DAP or SCS hold pretty easily. The P51 marks have a larger tolerance and again it's just "orientation."

The deltas seen above I could not replicate, I was getting 00001 at the most without using any killrot in the posted scn.
 

thermocalc

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Hi, I would like to ask for some clarifications.

Q1) During day 9 when I was supposed to carry out the “HGA test” at time 192:40:00 there was a yellow text instructing to “yaw right approx. 30 degrees out of plane north” and similarly at time 194:27:00 another yellow text instructing to “yaw left approx. 30m degrees out of plane south” … in photo 1 and photo 2 the 2 cases showing the YAW attitude in which I was before doing P52.

Was I correct entering into such attitudes?

“Out of Plane North” -> means at yaw <360 (350, 340, 330, …)?

“Out of Plane South” -> means at yaw >0 (10, 20, 30, ….)?

Or it is the “opposite” of what I stated above? or a completely different things?


Q2) The “Block Data” PAD which come from time to time are supposed to be used for “ABORT” reentry scenarios right?
In such cases how to use the information displayed?

With reference to the PAD values in photo 3 for example:

XX 124-4B AREA

XXX +34.7 LAT

XX -163.0 LONG

196:12:22 GETI

XXX 252.0 DVC

if problems arise at a particular time, let's say at 195h, than I could chose to deorbit at any GETI available greater than 195h right?
so let's pick up the deorbit burn at GETI 196:12:22 with a Delta-V of 252.0 fps -> how to de-orbit? Should I enter the 252.0 into the EMS DV counter and burn in RETROGRADE attitude at the GETI time? and I will landing near to the LAT, LONG coordinates (and recovery zone) mentioned?

OR these values: target LAT/LONG and GETI, DVc, are meant to be used as initial “guess” solution to be entered into the P37 Return to Earth program? And the exact TIG, DV and burn attitude will be calculated by P37 itself and the burn will be done via P40?

I would like to try once to re-enter using the information provided in this PAD…

Thanks.
 

Attachments

  • photo 1 - yaw right 30 degree out of Plane North.JPG
    photo 1 - yaw right 30 degree out of Plane North.JPG
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  • photo 2 - yaw left 30 degree out of Plane South.JPG
    photo 2 - yaw left 30 degree out of Plane South.JPG
    86.8 KB · Views: 46
  • photo 3 - BLOCK DATA PADs.JPG
    photo 3 - BLOCK DATA PADs.JPG
    63.5 KB · Views: 43

n72.75

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Just so you know, with the HGA test: the signal source location is currently the center of the earth + mean radius. So the antenna wont track actual ground stations yet. This is on my list of things to add, but I need to understand how the station handover works a bit better first.
 

rcflyinghokie

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Q1) During day 9 when I was supposed to carry out the “HGA test” at time 192:40:00 there was a yellow text instructing to “yaw right approx. 30 degrees out of plane north” and similarly at time 194:27:00 another yellow text instructing to “yaw left approx. 30m degrees out of plane south” … in photo 1 and photo 2 the 2 cases showing the YAW attitude in which I was before doing P52.

Was I correct entering into such attitudes?

“Out of Plane North” -> means at yaw <360 (350, 340, 330, …)?

“Out of Plane South” -> means at yaw >0 (10, 20, 30, ….)?

Or it is the “opposite” of what I stated above? or a completely different things?
So this is after SPS 7 so you should have a posigrade REFSMMAT. So if your spacecraft is facing prograde you yaw left for north and right for south.

Q2) The “Block Data” PAD which come from time to time are supposed to be used for “ABORT” reentry scenarios right?
In such cases how to use the information displayed?

With reference to the PAD values in photo 3 for example:

XX 124-4B AREA

XXX +34.7 LAT

XX -163.0 LONG

196:12:22 GETI

XXX 252.0 DVC
Yes that is for a deorbit burn if necessary. Since in LEO they had many LOS and AOS sites, they would need this onboard if they needed to deorbit while not in comms.

if problems arise at a particular time, let's say at 195h, than I could chose to deorbit at any GETI available greater than 195h right?
so let's pick up the deorbit burn at GETI 196:12:22 with a Delta-V of 252.0 fps -> how to de-orbit? Should I enter the 252.0 into the EMS DV counter and burn in RETROGRADE attitude at the GETI time? and I will landing near to the LAT, LONG coordinates (and recovery zone) mentioned?
This is correct, basically you could use SCS/GDC for this burn or even the 31.7 degree line on the LH window on the horizon if you didnt have it.

OR these values: target LAT/LONG and GETI, DVc, are meant to be used as initial “guess” solution to be entered into the P37 Return to Earth program? And the exact TIG, DV and burn attitude will be calculated by P37 itself and the burn will be done via P40?
I dont think P37 was ever used in LEO, also it likely would have taken too long to punch all that in then get data spit back out. The block data was for a quick controlled deorbit that P61 could pick up from.
 
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