Apollo 7 ORDEAL

[thermocalc]

Hi,
I am new to this forum but a fun of NASSP.
I am using Apollo 7 scenarios, while I am still attached to the saturn IVB stage I saw that following the checklist provided once set up the ORDEAL it stay fixed on the LHLV all the time during the orbit while the FDAI 2 , which is set to GDC, is instead moving around ... but when I separate from the stage, and I am only with the CSM alone, setting up again the ORDEAL making V82, V83 maneuvering the CSM to Roll 0, yaw 0 and pitch up to reach again the local horizon (basically the aspect of the FDAI 1 and the Orbiter Surface display are the same) even if I set the average altitude, I flip the power switch to EARTH and to ORB RATE, after that I see that the CSM is not mantaining the LHLV attitude and even the FDAI keep changing, it doesn't stay fixed to the local horizont, it looks like the CSM is still keeping a fixed attitude respect some stars....what I am doing wrong?
thank you. PLEASE to the moderator, accept me in the forum and let me get my answers...thank you.

 

[Thespacer]

You seem to be following the checklist correctly. As far as I can tell, what you are seeing is perfectly normal behaviour.

While the CSM is attached to the SIVB, the SIVB automatically changes its pitch to keep the pitch, relatively to the local horizontal, at 0 degrees.

When the CSM is separated, however, then there is no automatic* way for the CSM to change its pitch.

*I believe there is some way to program the CMC to get the DAP to effectively follow the local earth horizontal - at least in Apollo 9 (I haven’t flown Apollo 7).

 

[thermocalc]

thank you very much; indeed I was thinking that it was the IU in the SIVB stage that was controlling the pitch rate of the whole vehicles...but once separated the CSM doesn't control it automatically (at least).
Somewhere in the Apollo Operational Manual or WIKI docs I think to have red (I am still try to look where it was written...) something like..."The ORDEAL only commands the pitch rate of the FDAI...and not the attitude of the CSM"...at that time I didn't fully understand the meaning, now it all makes more sense
I also found a G/N checklist in which it says how to set up a orbital pitch maneuver manually using the SCS and the scenario editor to set up the correct orbital pitch rate in degree/sec...I tried and more or less it worked...but I was wondering if there was a way "internal to the AGC" to make this happen...anyway, it seems that for Apollo 9 it is possible...maybe it is only question of the type of SW that was written on the AGC of that particular mission...anyway, thank you for you kind explanation...I am happy for the time being. Cheers. Paolo

 

[indy91]

but I was wondering if there was a way "internal to the AGC" to make this happen...anyway, it seems that for Apollo 9 it is possible...maybe it is only question of the type of SW that was written on the AGC of that particular mission...

Yes there is. For Apollo 13 and earlier you have to use a complicated procedure manipulating DAP settings. A bit scary, one mistake and the DAP might do very undesirable things. That procedure can be found in the AOH Volume 2: https://www.ibiblio.org/apollo/Documents/AOH_A16_VOL2_Part_1.pdf on PDF pages 304 to 310. On the later missions (Apollo 14+) this orb rate procedure is integrated into P20, so there it is fairly easy to do.

 

[thermocalc]

Thank you Indy91,
my fault, I didn't read that manual you provided me yet, I am still studying the Apollo Operational Handbook - spacecraft description as well as the DELCO manual for the AGC ... many things to read ehehehe ... OK, I saw it and indeed it sounds quite complicate to master for the time being, anyway I will try to understand it as much as I can...for the time being I am happy to know that all I was doing was correct and happy to knows that in later missions the ORDEAL procedure will get simplified.
Thank you again and let me tell you that I am a great admire of you, it is a real honor for me to talk to you...I am trying to study all your rendezvous MFDs and procedures...so far without success :facepalm: but hopefully one day I will make it, thanks also to have been accepted in this forum .... thank you again for your time.
Kind regards, Paolo

 

[Thespacer]

The RCS DAP Orb Rate procedure in the AOH works well, I just tried it around earth.

 

[thermocalc]

Thank you all; nice to know it works, i will give it a try as soon as i manage to understand what i am supposed to do to set up the DAP...anyway, for the time being I am using the PITCH ORBIT RATE MANEUVER (SCS) as described in the doc G/N check lists and it works...if really cannot figure out how to use the DAP i may come back later to this topic. Thank you again.

 

[thermocalc]

Sorry, I make a mistake, I address this post in another treat, please forgive me now it is in the correct place.

I tried the AOH procedure but nothing happened to me, i am sure I am making something wrong here and I didn't fully understood what I am supposed to do, so if you have time I would be glad to get some help from you as you did it.
Q1) when it says "use R02 to disable 2 adjacent RCS quads" -> I run V48 and I loaded into R2 the string 11010 (I use only quads A/C, so I disabled B/C ... I think?)
Q2) when it says "perform V49" to "load gimbal angles for init of orbrate" I only entered the RPY angles in N22 (V16 N22) "as they are indicated on the FDAI1 set in ORB RATE EARTH) - I didn't completed the automnvr as otherwise the vessel get pointed in another direction as he will interprets those angles as INERTIAL --- (I was checking with OrbiterSurface MFD and more or less I was "wing level head downs", so I had about R=180, P=Y=0 as I set up the FDAI to have ORDEAL reference (FDAI1 shows same as orbiter surface attitude indicator) -- of course I cannot keep all angles perfectly centered, even i hit KILL ROT on projectApollo MFD some small drift is always there) --- as the only angle which was drifting was the PITCH I entered in N22 a value as R=180, P=005, Y=000 .... i saw that it took many minutes to go from 0 to 5 degree in PITCH so i had time to enter all data in the AGC and hit ENTER to start the mnvr.
Q3) I wanted to set orbital pitch rate of -0.075 degrees/s heads down, so I look at the table at page 4-293 for the values to enter for CDUX = 180°, I suppose CDUX is X spacecraft axis around which ROLL is measure by the IMU (X=roll axis=CDUX, Y=yaw axis=CDUY, Z=pitch axis=CDUZ, am I correct here with the axis-angles relationship?)
VVVVV=00002
WWWWW=13100
XXXXX=77775
YYYYY=51300
ZZZZZ=52117
Q4) then I entered everything as described at page 4-291 and when I hit the last E at 7000E nothing happened even after waiting for the pitch to have been moved well beyond the 5° that i entered into the N22....but I saw on the FDAI1 that by the time I hit the last "E" on the AGC due to some drift ... the R and Y where not really at 180 and 0 anymore....they were off target some degrees....

don't know what I am doing wrong....

any help/suggestions?
thank you.
Paolo

 

[Miriam]

when it says "use R02 to disable 2 adjacent RCS quads" -> I run V48 and I loaded into R2 the string 11010 (I use only quads A/C, so I disabled B/C ... I think?)

Seems right. However, this would have no influence on how the maneuver comes out. It's just for saving fuel.

Q2) when it says "perform V49" to "load gimbal angles for init of orbrate" I only entered the RPY angles in N22 (V16 N22) "as they are indicated on the FDAI1 set in ORB RATE EARTH)

...and that's wrong. Those have to be inertial angles. We use the DAP for this stuff, and the DAP has no knowledge of how the CSM is oriented in terms of LVLH. It simply uses the actual IMU gimbal angles, no more, no less.

VVVVV=00002
WWWWW=13100
XXXXX=77775
YYYYY=51300
ZZZZZ=52117

Those are strange. My AOH has
VVVVV=00002
WWWWW=20700
XXXXX=00000
YYYYY=12300
ZZZZZ=53467.
However, this should just lead to a wrong rate. It should do something.

when I hit the last E at 7000E nothing happened

When you really missed the last 0 (it's got to be 70000E): that's the mistake. This will not reset the HOLD flag and the maneuver won't start.

 

[Thespacer]

Q3) I wanted to set orbital pitch rate of -0.075 degrees/s heads down, so I look at the table at page 4-293 for the values to enter for CDUX = 180°, I suppose CDUX is X spacecraft axis around which ROLL is measure by the IMU (X=roll axis=CDUX, Y=yaw axis=CDUY, Z=pitch axis=CDUZ, am I correct here with the axis-angles relationship?)
VVVVV=00002
WWWWW=13100
XXXXX=77775
YYYYY=51300
ZZZZZ=52117
Q4) then I entered everything as described at page 4-291 and when I hit the last E at 7000E nothing happened even after waiting for the pitch to have been moved well beyond the 5° that i entered into the N22....but I saw on the FDAI1 that by the time I hit the last "E" on the AGC due to some drift ... the R and Y where not really at 180 and 0 anymore....they were off target some degrees....

I have only tried this procedure from an LVLH pitch of 0 degrees (heads up). I recommend you try the same, as I do not think CDUX 180 degree values coincide with Roll of 180 degrees. I could be wrong, I haven’t tried it. Also I just cross-checked the figures in that table (for -0.075 rate) with your post, and while you correctly list VVVVV=00002, the rest of your figures are from the +270 degree values.

Suggest, for ease of trouble shooting, you also try the procedure from a circular orbit, set up ORDEAL accordingly, and use the heads up attitude (and 0 degree CDUX values), as I can assure you that this works. I would also recommend, if you are not already, using the keyboard CMC shortcuts, as that minimizes wrong clicking and makes the procedure very quick. Ideally, you want to time it so that the DAP starts the manoeuvre when your Theta is 0 (assuming the starting condition I’ve just outlined).

 

[thermocalc]

OK, thank you.
I will try to do as you suggested and let you know.
I don't know of any AGC shortcut keyboard ... I think I didn't see anything like that in the original Wiki for NASSP....anyway if you can kindly let me know "which" keyboard shortcuts are available in the sim they might be useful ... thank you. Paolo.
...but to do as you said...do I still need to deactivates some quads in V48? if so, what string should I enter in R1 and R2 when setting up the DAP?.
if i understood you correctly i only need to put the craft in LVLH attitude before starting entering all the values xxxxx, yyyyyy, and so on .... am I right? so no need to play around with V49 before to attempt the mnvr?
thanks.
I will try tomorrow, now too late for me...

 

[Thespacer]

1. Keyboard shortcuts for the DSKY are listed in a sticky thready in this forum - basically Shift key + numpad.

2. The V48 procedure seems to be optional as an RCS fuel-saving measure. In any case I did not see anything wrong in your procedure.

3. The V49 procedure is also optional. The key point is that you manoeuvre to the appropriate attitude for the initialization of the procedure, which should be easy if ORDEAL is set up (using V83). As you know, the desired gimbal angles for V49 will be inertial and therefore the pitch attitude will probably not coincide with 0 degrees LVLH.

 

[thermocalc]

Hi all,
yes indeed I saw that I wrote wrong information last time, mixing numbers for CDUX 0, 180 and 270 ... sorry for the confusion.

anyway this time I started in EPO (Apollo7) in FDAI1 ORDEAL set up by V83 with R/P/Y=0/0/0, the yellow error needles were all centered, i didn't do V48 (let on all quads: R1 11102, R2=11111) -> so i was already "wing level heads up", confirmed also by OrbiterSurface MFD; I didn't do any V49 and I didn't enter any attitude in V16 N22 ... I was expecting (according I understood reading all your comments) that by hitting/keying the last "E" in 70000E the craft should start pitching at -0.075 degrees/sec (and this time i made sure to use the correct numbers for CDUX=0) .... indeed I saw the RCS jets firing (by pressing E) but the SC started to spin out of control, with P, R, Y commanded rates above 0.5 degress/sec (even nearly 0.8 I got in pitch) in all axis without stopping or decreasing, all three yellow needles fly out of their end scale just after having pressed the E (I was using ERR/RATE 5/1 setting in the FDAI) not a orb rate for sure :lol: .

So I restarted all over again, this time I checked how long it takes to me to digit all the procedure (making slowly to cross check what I entered reading first from a piece of paper) and when I start the FDAI1 was not at pitch zero, but slowly going turning upward, at the end of keying data I am still at few degrees from pitch zero, V83 R3 says about 2-3 degrees, I wait and when I see on the register R3 of V83 "zero", cross checking that also the FDAI 1 is nearly at pitch zero, I hit the last "E" .... again I got the RCS jects firing and the craft starting again to spinning/thumbling out of control, again with rates >0.4 degree/sec on all axis.

the only common features, that I didn't try, was to set up via V16 N22 the equivalent pitch angle read on FDAI2, still in inertial coordinates, when eventually I get pitch 0 on R3 in V83 ... but again, reading your posts it should make no difference ..all I have understood is that I have to timing to start the mnvr (i.e. hit the last "E" in 70000E) when R3 in V83 is ZERO or the ORDEAL FDAI1 pitch scale is ZERO....am I wrong again?

> I will try again the procedure in the next days, not in an hurry, collecting results, if still negative i will summarize all I have attempted, with results, for you further considerations....thank again to take your time :facepalm:e

actually I was thinking to try this crazy things (if it works at all): if I deselect all Roll and Yaw quads letting ON only the pitch controlling quads and then doing the procedure there should be no way for the DAP to start angular rates in R and Y ... another remark, the last bit in R1 on V04 N46 is used to set up the rate...i always left to 2 = 0.5, but it should make no difference as the speed at which it will turn will depend on the string of octal numbers that the CDUX tables says...so (I think) those tables should somehow override the rate value set in R1 on V04 N46 .... ? anyway, next time i will set it to 0 = 0.05 degree/sec or 0.10 degrees/sec and see if something change...

thanks again for reading me ....