Apollo 16 Post LOI-1 Questions

Wedge313

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Just completed the LOI-1 burn. The good news is the orbit is 170 x 59, and appears to pass over Descartes. But a few things that I have questions about....

When I calculated MCC-4, my PAD attitude had my yaw at 283 degrees, which would have put me into a gimbal lock situation. I wasn't sure what to do with this, but ended up trying a switch from the PTC REFSMMAT I was in to a P30 REFSMMAT for the burn, and that seems to have worked. But I'm not sure if that was a correct solution or if there's a better way to do that?

When I ran P30, it showed my resultant Ha as +0345.4 and Hp as -0092.6. Not what I expected to see. I re-calculated the burn, but couldn't see any change in the result, the PAD Ha and Hp looked good, but P30 Ha and Hp still showed +0345.4 and Hp -0092.6. I couldn't figure out what I did wrong here. For lack of a better idea I went ahead and did the LOI burn, and ended up in what looks like a good orbit (170 x 59). I'm not clear on why the P30 showed that Ha and Hp?

Finally (for now) is there a good source to find the Apollo 16 documents? I got spoiled with Apollo 15, there was a ton of documentation. But for Apollo 16 I'm using the limited documents I can find, and filling in with the Apollo 15 stuff as necessary. So far no major issues but I wonder if this will create a problem later in the scenario?

Thanks.

P.S. Another NASSP v1833 comment, I notice I seem to have more control over my attitude, it's much easier to maneuver, to null rates etc. Was something tweaked here? If so, well done.
 

indy91

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When I calculated MCC-4, my PAD attitude had my yaw at 283 degrees, which would have put me into a gimbal lock situation. I wasn't sure what to do with this, but ended up trying a switch from the PTC REFSMMAT I was in to a P30 REFSMMAT for the burn, and that seems to have worked. But I'm not sure if that was a correct solution or if there's a better way to do that?

According to the mission techniques update document for Apollo 16 and 17 this is exactly what they would have done for middle gimbal angle > 60°.

When I ran P30, it showed my resultant Ha as +0345.4 and Hp as -0092.6. Not what I expected to see. I re-calculated the burn, but couldn't see any change in the result, the PAD Ha and Hp looked good, but P30 Ha and Hp still showed +0345.4 and Hp -0092.6. I couldn't figure out what I did wrong here. For lack of a better idea I went ahead and did the LOI burn, and ended up in what looks like a good orbit (170 x 59). I'm not clear on why the P30 showed that Ha and Hp?

This always happens with LOI-1, especially when there is CSM+LM. From the Colosuss 3/Luminary 1E program notes:

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Finally (for now) is there a good source to find the Apollo 16 documents? I got spoiled with Apollo 15, there was a ton of documentation. But for Apollo 16 I'm using the limited documents I can find, and filling in with the Apollo 15 stuff as necessary. So far no major issues but I wonder if this will create a problem later in the scenario.

I wished there was. But there is an "ok" amount of documents. I'm sure you have collected everything there is on AFJ and ALSJ, there also is the LM Activation Checklist on the Virtual AGC website. If you have looked at those three websites then you have as many Apollo 16 checklists as I have.

P.S. Another NASSP v1833 comment, I notice I seem to have more control over my attitude, it's much easier to maneuver, to null rates etc. Was something tweaked here? If so, well done.

I don't know when you last updated your NASSP. Back in September I changed the SM RCS thruster directions a little bit to now very accurate values. But otherwise I can't think of anything that would have changed.
 

rcflyinghokie

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Finally (for now) is there a good source to find the Apollo 16 documents? I got spoiled with Apollo 15, there was a ton of documentation. But for Apollo 16 I'm using the limited documents I can find, and filling in with the Apollo 15 stuff as necessary. So far no major issues but I wonder if this will create a problem later in the scenario?
As far as procedures go, you can get away with using the Apollo 15 docs to supplement the missing 16 ones as they are quite similar on 15 through 17.

P.S. Another NASSP v1833 comment, I notice I seem to have more control over my attitude, it's much easier to maneuver, to null rates etc. Was something tweaked here? If so, well done.
I would be willing to bet it was you getting used to how everything flies and being able to control it better :) I don't think anything changes wrt RCS or maneuvering since your 15 run started.
 
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