Advanced Question Accurate Apollo TD&E

The 2-Belo

Capt. Refsmmat
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I wonder if someone whom has done this via the historical numbers can help point me in the right direction (puns; see below) on what is the proper way to transpose the CSM and dock with the LM in the Apollo 11 mission without using up too much thruster gas, but at the same time not "cheating" (i.e., cutting corners that Mike Collins did not).

1) My issue lies in what actions to take immediately after separating from the S-IVB. Once the four panels have fallen away the CSM is floating free, and at this point I'm supposed to pitch up, turning toward the LM for the docking attempt. But since the separation maneuver has put in a bit of a forward rate with respect to the S-IVB, by the time I turn around I've floated a good ways away from the booster, and it's even put in a little motion up and away from the line of sight.

I've figured out how to correct this (at least in Orbiter) by waiting about ten seconds after separation, switching to linear RCS, and thrusting backwards to null out the rate so I'm at zero velocity with respect to the S-IVB. But is this what Mike Collins did?

I suspect that there was some point where he stopped the outward movement, but was this before or after he pitched around? The Orbiter sim is realistic enough that you can see debris floating by the windows after the panels have separated; is a little distance necessary to make sure nothing hits the CM?

2) The other thing is, after I've ejected the LM from the booster, what to do with the S-IVB afterwards. In the real mission the flight controllers oriented the booster so it would slingshot around the other side of the moon and into a heliocentric orbit. This was done by venting the remaining propellant (rather than actually firing the engine, since it could only be fired twice). I suppose I should do it by switching ships to the S-IVB and then mashing down on the thrusters, but it seems like it never runs out of thruster gas, and I'm not sure what attitude to orient it. Should I just set up a maneuver using TransX like I would with any other vehicle?

Sorry for length.
 
1.) You must have a distance to the LM and turn the 180° around.
In the upper panel there is a cross that is also outside of the LM
line up with the dockingport.

After sepperation forward
then stop
180° turn
roll to line up the crosses
forward and docking

2.) You can simulate this. But I don't simulate this.
And when you do it you could use interplantary course programm to
do a free return.
 
1. Use attitude mfd during the docking procedure to kill your realtive motion whenever required.

2. AMSO already shifts the IVB for you a few minutes after LM extraction - doing NASAs job.
 
Actually I'm running NASSP, with the Virtual AGC (it's taken me nearly two weeks to get to this point strictly going by the real checklists!), so I don't see anything happening to the S-IVB after I pull away.

And re: the docking procedure: Yes, I was able to successfully line up and dock after I reverse-thrusted to a stop before I pitched around. I just wonder if that was the proper procedure in real life.
 
And re: the docking procedure: Yes, I was able to successfully line up and dock after I reverse-thrusted to a stop before I pitched around. I just wonder if that was the proper procedure in real life.
Reading the Apollo 10 Flight Journal, that is what they did: http://history.nasa.gov/ap10fj/as10-day1-pt4-tli-docking.htm (read comments at 003:02:51), but Apollo 15 tells a different story: http://history.nasa.gov/ap15fj/03tde.htm (read comments at 003:23:08). No doubt the procedures were refined over time.
 
I believe the SIVB autopilot is coming in a near-future version of NASSP. I also suspect the separation velocity may be too high in this version?

I'm not sure about the thrusters: I suspect the thrust is low enough that they can fire for quite some time before they run out of fuel.
 
Reading the Apollo 10 Flight Journal

Oh, now this is just what I needed. Thanks muchly.

(It even has graphics of what switches were thrown for what maneuver. Perfect!)

---------- Post added at 11:59 AM ---------- Previous post was at 11:56 AM ----------

I also suspect the separation velocity may be too high in this version?

That's also what I suspected, because at the rate I'm supposed to pitch around (5 deg/sec?) I'm quite a ridiculous distance away from the LM when I finally see it (and I always make sure to use the reticle for docking). I tried looking for a config value I could play with, but I guess that's internal.
 
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