Problem Counting RR 5 Marks in LEM AGC- Apollo10

[sw34669]

 

[indy91]

Well done!

After doing a number of approaches i'm still struggling a bit to get the alt's converged and end up hot and high, not by much. A detailed look at the process talks about dropping the thrust to 10% until converged. Any advice here.

Not quite sure what you mean. The DH on N68 doesn't converge? Is the landing radar is doing its job? Where did you find the procedure with the 10% thrust?

The other area is the TLAND AGS variable needed (LM Epoch). I found that RTC MFD / Utils / LGC will calculate 2 of them, but, not sure what to enter here.

Hmm, right. The LM Timeline Book actually uses a nominal TLAND there, 254+0767.2. Have to look through the transcript if that gets updated. And the Timeline Book also says to load address 240 with the same value as address 231 (landing site radius), which is a number found on the PDI PAD. So I think I'll just tweak the checklist there a bit. Always use the 767.2 for address 254, as I don't think the precise timing of that is critical. And then let it load 240 with the value from address 231 from the PDI PAD.

 

[sw34669]

there's a bunch in duke uni (will need to find the link) that inrtervied a bunch of people, looking at man/machine interfacing and they seemed to have a fairly detailed description of the pdi process. http://hal.pratt.duke.edu/sites/hal...Apollo Lunar Landing Voice Communications.pdf

It was the interview notes associated with that paper. They were so detailed about each exact part of the PDI/Approach and landing. It seemed to be saying that thrust to zero until the correct attitude and approach was attained. Obv could be an error. I cant get onto http://www.ibiblio.org/mscorbit/mscforum/ at the moment as the forum i found it on is borking.

I've attached the start of PDI scenario you can tell me what you think when you have a moment. It is updating just seems a large delta h to start with. The result is by 8 mins and shifting into p64 almost on top of the landing site. I probably have something wrong.

thanks

 

[sw34669]

i seem to end up (after enabling radar upadting) to have an increasing dh not reducing. here's the PDI PAD from MCC i'm using. thanks

 

[indy91]

Ok, I tried your scenario. A few notes. The first DH that comes up in N68 is 5800 feet. That is pretty large, what I usually see is up to 4000 feet for Apollo 11. That nominal DH is mainly explained by bad astronomy. They could determine latitude and longitude of the desired landing site very accurately from Earth. But radius of the landing site not so much. All prelaunch estimates of the landing site radius for all Apollo missions were off, and in most cases they were improved by data from P22s done by the CSM. Not quite sure if they got to use that data for Apollo 11. But without such an update a few 1000 feet difference is actually expected. So the Landing Radar has some work to do.

I don't know why it's even larger for you, could be a bunch of things. Might be a degraded state vector, just like the real Apollo 11 mission had, although they mainly had it downrange. But for me it still converges without too much trouble. Just like in your picture above it overshoots the landing site, but not by a terrible amount.

So a few questions. Did you have a good P52 before DOI? You did the ca. 180° yaw maneuver so that the landing radar can point down? And then later, you did the V16 N68 and checked R3 which has the DH. And then the V57E. And then continued to monitor V16 N68 to see if R3 becomes smaller? Because for me it does converge. You fly over a bunch of craters of course, so the DH value going up and down a bit is expected. But as long as it converges in the long run you are good.

 

[sw34669]

that's interesting, of course, a lot of the approach maths had to be estimated thanks for the insight. I wil now answer your questions

1) P52 may have been partially CBI ......... compromised by ignorance
2) Yes - although it's a challenge not to have it thrashing around like a firework, i've got better, at it.
3) Tried to get V57E asap to see if that helped but, as you say, I was already hight, prob due to 1)
4) Understand the radar fluctuation due to

Will fly it a few more times, the LPD thing is also great with the control lag, reminds me of a car i used to have with 30mm of play in the steering bearing

Ok, get ahead of me now, what are the 3 bits of advice I take real care with for the ascent. I can guess 1 is good astronomy.
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yep, my position at PDI start is impacted by poor obs prior
If I get the yaw 180 and V57 in early it fully converges
learning p52+57 important