Apollo 11 Docked IMU Coarse Align?

Wedge313

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Hello, I'm trying to get the coarse alignment for the LM, and need some help....

When the checklist says "calculate LM gimbal angles" what do I do? I grabbed the LM gimbal angles displayed on the PAMFD LGC page. For me they were +023.58, +055.06, +358.45. This is what I loaded into V21N22. I get the NO ATT light. At this point the FDAI shows R 000, P 055, Y 336, and stays that way after I enter V40N20 (the NO ATT goes out).

Shouldn't the FDAI show the angles I just entered? Or (as I suspect is the case) do I have no understanding what I'm trying to accomplish here?

Thanks
 

Miriam

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That seems right. Remember, the LM has the axes arranged differently then the CSM: what you'd call yaw in the CSM is roll in the LM, what you'd call roll in the CSM becomes yaw in the LM. That's why the FDAI in the LM has no red zone on the ball itself, but on the outer bezel.
 

Wedge313

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Ok! The light just came on, I think....although it's only a 4 watt. So the pitch (055) stays the same, the yaw value of 358 becomes a roll of about 000, but I'm not clear how the roll value of 024 becomes a yaw of 336. With some mental gymnastics I can see what's going on now, with only a little blood oozing from my ears, but I need to work on it. Thanks for the explanation.

This is my second time working through this part of the Apollo 11 scenario. My first attempt was doomed because I found the learning curve too steep. Lots of things I had questions about (like the LM alignment). I fought through the checklists trying to manually configure the LM, getting out of sequence on the "switch to LM" or "switch to CM" prompts, and too often it became a "where's Waldo" looking for switches etc. I got further and further behind until finally by the time DOI should have happened I was 20 minutes behind schedule! So I'm going through a second time, and this time I hope a little better planning will get me through on schedule.

I appreciate the help.
 
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rcflyinghokie13

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Yeah going back and forth between 2 vehicles is a lot of work. I can say the sequence is in order but its very very easy to get it out of order.
 
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