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Author Topic: Apollo 7 Rendezvous with S-IVB  (Read 6152 times)
DrLaufbahn
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« on: February 06, 2007, 08:06:20 AM »

In an older topic, movieman wrote

From what I remember, it opened but the panels kept wobbling around because there was no air to damp their motion, so they were scared that the CSM might be hit if they tried to 'dock' with it. That's why they switched to separating the panels.

I had a look at the Apollo 7 mission report: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760072144_1976072144.pdf

According to this, the one panel which was not fully open at the time of the rendezvous had apparently been fully open at some point.  This was deduced from the condition of a restraining cable, which would only have been drawn out when the panel opened fully.

Note to legion: perhaps the above-referenced mission report contains the answer to your question about the orientation of the S-IVB during the rendezvous.  Published pictures of the stage might also help to answer the question.
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legion
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« Reply #1 on: February 07, 2007, 08:18:47 AM »

Note to legion: perhaps the above-referenced mission report contains the answer to your question about the orientation of the S-IVB during the rendezvous. Published pictures of the stage might also help to answer the question.

thanx dr.

i already got the apollo 7 mission report, but the s4b/csm attitude at seperation wasn't so clear to me.
better: seems i missed this part somehow. thx. now i understand!

legion
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irnenginer
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« Reply #2 on: February 07, 2007, 11:24:40 PM »

I spent some time looking into this when I was researching Apollo7. I determined that the most likely orientation was in a "vertical up" with respect to the earth ground. roughly facing toward the sun at an angle. This orientation would allow the best viewing angle to the SIVB during the simulated docking maneuvers. Photos of the mission appear to back up this orientation. Look at the Wikipedia entry for apollo7 to see what I mean:

http://en.wikipedia.org/wiki/Image:As7-3-1545.jpg

Later on at 1st phasing the CSM is orient prograde and use the -X jets for the maneuver. This orientation allows for tacking of the SIVB using the optics without have to turn around. The "Vertical Up" orientation of the SIVB would facilitate spotting it with the sun shining on the side of the spacecraft. At least until it started to tumble.

I was going to answer the original post but it was locked.
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Tschachim
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« Reply #3 on: February 08, 2007, 05:37:41 AM »

I was going to answer the original post but it was locked.

Yes, no clue why/how, but I unlocked it again.
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DrLaufbahn
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« Reply #4 on: February 08, 2007, 09:41:28 AM »

Does anybody know how close an approach to the S-IVB was originally intended?  The presence of a docking target makes me suspect that a very close approach might have originally been in the plans.  I have a copy of Walt Cunningham's autobiography, "The All-American Boys," but it doesn't mention this.
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legion
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« Reply #5 on: March 15, 2007, 11:37:02 AM »

thx. now i understand!

ahh i got a final question to seperation at last: in option a) and b) of the NORMAL SC/BOOSTER SEP CHECKLIST theres a >compute sep att<. there the checklist says R17 = R20 (same for pitch and yaw)..
does this have anything to do with the icdu angles (e.g. p20 + p att mfd = pitch icdu agles + pitch att mfd angles ?)

and what is hds (also in booster sep chcklst)? nasa acronyms = HARDWARE DISCRIPTION SHEET?

thanx for help

legion
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Christophe
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« Reply #6 on: March 16, 2007, 01:56:29 PM »


Quote
and what is hds (also in booster sep chcklst)?


hds = heads
You usually find this acronym followed by up or down
Hds up = heads up: Vessel is turned such as the astronaut's heads are pointed toward the space
hds dwn = heads down: Vessel is turned such as the astronaut's head point toward the earth (or moon while orbiting around the moon).

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in option a) and b) of the NORMAL SC/BOOSTER SEP CHECKLIST theres a >compute sep att<. there the checklist says R17 = R20 (same for pitch and yaw)..
does this have anything to do with the icdu angles (e.g. p20 + p att mfd = pitch icdu agles + pitch att mfd angles ?)

Well... look at the "Doc\Project Apollo - NASSP\Check List\G&C checklist\colossus_1A_249"
In the part 1 "CMC_general", page 1-8, you have the list of available noon.
Look at Noon 20. It is said: "present ICDU angles". In other words, it's the present attitude that is currently displayed on the FDAI.
Look at Noon 17. It is said: "astronaut total attitude"
What does it means, you probably ask?
 This is simply an attitude that the astronaut want to have at some specific time, and they want to be stored into the CMC memory. This attitude is expressed in the form of ICDU angle, exactly like the N20's attitude is.
Then, look at the page 1-7 of the same part 1 CMC_general checklist. It's a part of the available verb list. Look at the Verb 63. It is said: "Mode 3, Display total astronaut attitude error (N17-N20)"
When a checklist says the word "error" it doesn't refer to some unwanted mistake ( Undecided) but refers to the error needles: the 3 yellow bars that can move across the FDAI
So, when you have entered a "total astronaut attitude" into the CMC via N17 and then when you key V63 into the DSKY, the error needles will move away from the centered position because they trend to indicate the difference between the desired attitude and the current one: N17 - N20 .
Then, rotate the spacecraft into the direction indicated by the error needles: when they will be centered again on each axis, then you will be on the desired attitude and the ICDU angles are those you have entered via the N17.

So let's go back to the separation attitude problem.
In real flight, this attitude was computed by the ground.
In NASSP you can determine a valid (but not absolutely and historically coorect) with the help of the attitude MFD.
Roughly, you have to point toward the sun in order for the LM to be lighten by the sun when you turn around and go forward to dock.
That's will I simply recommended in the checklist to use the Attitude MFD with the sun as a target to compute the desired attitude for the separation maneuver.
So, bring up the Attitude MFD, go to mod "target relative", set the sun as a target and copy the Pitch and Yaw attityude displayed on the MFD.
Key V16N20E on the dsky. It will show your present atttitude, in fact the present ICDU angles that are displayed on the FDAI.
Then, the FDAI/ICDU angles for the separation are very easy to compute; It is:
* Roll for separation= your present roll; (the R1 displayed ont the DSKY when V16 N20. That's what's called "R20")
* Pitch for separation = you present pitch (P20) plus the pitch value from Attitude MFD
* Yaw for separation = Your present yaw minus the yaw from attitude MFD.

Then key V25N17E and load the results into the CMC.
Now your separation attitude is into the CMC memory. Once you've further keyed V63, the error needles will display the difference (the "error") between your separation attitude and your present attitude. Following the error needles direction will "drive" you to the separation attitude.

The other usefull attitude for the mnvr is the docking attitude. This attitude and its related ICDU angles can also be loaded into the CMC with, this time, the help of the N22.
I let you looking at the noon list to get the definition.
It works exactly on the same way than the N17 and you can use the help of the error needles by keying V62 instead of V63.
The docking attitude computation is given by the "NORMAL SC/BOOSTER SEPARATION" checklist too:
Docking roll (R22) = 315 minus Separation roll (R17)
Docking pitch (P22) = Separation pitch(P17) plus 180
Docking yaw (Y22) = 360 minus separation yaw (Y17)

Hope this could help you.

Cheers
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legion
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« Reply #7 on: March 18, 2007, 02:40:31 PM »

hallo christophe

yes for sure hds means 'heads', i always noticed when it was written in small letters...in this case i thougt about an assembly the hole time. pardon me for my stupidness.
And i really had a broblem with the 'astronauts'-att. i am german and my english isnt rustet yet, but sometimes i got a problem with this specailised one.(  Confused)
thanx for your whole explanation. i hope this will help some other beginners too. you do a really god job with project apollo. with this forum, too. i love your sim. All you guys keep up the good work, one day i will construct myself a csm running with your sim(and lm will follow  Very Happy). think building a real flight simulator for project apollo would be a very nice thing..i often saw this for 'MS Flights..'..huhu with all those switches and cbs in real(in case of an apollo simulator).
but excuse me for now, i got a seperation to do  Cool

legion
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Christophe
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« Reply #8 on: March 18, 2007, 02:47:18 PM »

Quote
one day i will construct myself a csm running with your sim(and lm will follow  ). think building a real flight simulator for project apollo would be a very nice thing..i often saw this for 'MS Flights..'..huhu with all those switches and cbs in real(in case of an apollo simulator).

That's my dream too... Rolling Eyes

Who knows? May be one day this dream comes true and we spent some time in a CSM mockup.
Tschachim will be chief of astronaut office and will designate the crews  Very Happy
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tblaxland
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« Reply #9 on: May 21, 2007, 02:24:46 AM »

Some help for a newbie please...

I have been trying to separate and rendezvous with the S-IVB using the Apollo 7 quickstart scenario. After reaching orbit I start running through the "Normal SC/Booster Separation Checklist". All goes well up to and including "ALIGN GDC".

The next step brings me undone: "V48E". When I try and enter this into the DSKY, it accepts the "V4" then gives me an OPR ERR when I hit "8".

What's going on here? Am I missing something? What is the correct key sequence for loading the DAP at this point?

I noticed in the Colossus CMC General checklist the following "Caution! NASSP doesn't allow SIVB control in DAP mode". Is this the problem?

Thanks in advance for your help.

tblaxland
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Christophe
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« Reply #10 on: May 21, 2007, 06:52:16 AM »

V48 works only for vAGC which is not active in quickstart mode I believe.
Try vAGC scenario.
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tblaxland
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« Reply #11 on: May 22, 2007, 06:33:18 PM »

Thanks Christophe. I tried that and it worked just fine. I haven't had time to do the full rendezvous yet but I'll let you know if I have any other issues. You guys do a great job with this project BTW.
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tblaxland
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« Reply #12 on: May 28, 2007, 09:16:30 PM »

I loaded the DAP and did an auto-maneuver to the correct attitude for docking. I then closed in for simulated docking and station keeping. See external view. The attitude of the S-IVB is not historically correct however I'm pretty happy with achieving this on my first vAGC flight.

A couple of queries though. Before doing the auto-maneuver (V49E), I entered V62E. As I understand it, this should cause the attitude error (N22-N20) to be displayed on the FDAI error needles. The error needles did not show this, instead they stayed nulled (where they were from the last GDC alignment). V16N20E and V16N22E both showed (as far as I can tell) valid and different RPY angles. Am I doing something wrong on the AGC or could there be something wrong with the FDAI switches?

Also, historically speaking, does anyone know what error was allowable in the attitude between the LM and the CSM before contact? It would seem to me that the probe/drogue system would be more tolerant of attitude error than the androgenous system currently in use on STS/ISS.
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tblaxland
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« Reply #13 on: May 29, 2007, 05:47:24 AM »

I've answered my own question - I had somehow I managed to turn off the DAP. I activated the DAP and the error needles worked great! Sorry if I wasted anyone's time trying to find an answer.
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tblaxland
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« Reply #14 on: May 29, 2007, 06:28:14 AM »

I had a go at getting a more historically accurate rendezvous. See comparison. Not spot on, but about as close as I can get it.  Happy
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