RTCC no TLI PAD

Max-Q

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So I'm in orbit on Apollo 17, and when I went to calculate my TLI PAD with RTCC just as I have for all the other RTCC missions it gave me nothing; I press CLC and no pad shows up.
I'm running NASSP 2004ish, In GitHub I created a branch with the base 2004 package then added Jordan's new VC textures and my lunar surface update branch; then I downloaded and complied all modules.
I tried rebuilding RTCC MFD, and still nothing. I tested in other missions and it gives me a valid PAD in other missions.
If I press on without a PAD, the S-II SEP light never comes on and ignition happens without warning.
P15 also throws a program alarm shortly after ignition; I can't even get a V05 N09 in to see what the alarm is.

Scenario attached. Thanks in advance!
 

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  • Apollo 17 - TLI Prep.scn
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indy91

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I can confirm the issue. TLI PAD doesn't calculate in your scenario. I've tracked it down to the RTCC TLI simulation. Specifically at ignition where there is an attitude maneuver of a few degrees. The RTCC even simulates that, or at least the part where the LVDC would limit the attitude rate to 1°. The current pitch angle is e.g. about +175° and the required pitch angle is about -175°. Instead of doing a rate limited 10° pitch-down maneuver, like the LVDC would do at TLI ignition, the RTCC simulation instead chooses to go the long way around, a 350° pitch up maneuver... And then it runs out of propellant before achieving TLI, which leads to the TLI PAD error.

Seems to be a rare bug, never seen this with other missions and even an old Apollo 17 scenario where I had launched with the same delay as the actual mission worked. Actual TLI was 10 minutes earlier than with the planned liftoff time. So I guess in the coordinates that the LVDC uses the pitch down at ignition would be from e.g. +200° to +190° pitch and the bug doesn't occur.

I've opened a pull request with the fix: https://github.com/orbiternassp/NASSP/pull/925
 

indy91

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Fix downloaded, RTCC recompiled, and I have a TLI PAD! Thanks!
Any ideas on the S-II SEP light or P15?

Oh right, I forgot about that. I haven't checked P15 because I didn't have a TB6 time, but I did get the S-II sep light like normal when I tried it. Just had to go through the TLI prep checklist, in your scenario the EDS power switch was off and the SECS breakers weren't all pushed in. S-II sep light at least needs the EDS power on.
 

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Aha. 🤦‍♂️
I just skipped the pre-TLI checklist and timewarped ahead to see if the S-IVB would ignite at all... That makes sense now.
As far as P15, it also did this on 15 and 16, I just left it alone until after shutdown then went to P00 manually.
IIRC it is a 1204 alarm; the G&N book says if ave-g on to continue. It keeps updating the state vector but locks out the DSKY.
 

indy91

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As far as P15, it also did this on 15 and 16, I just left it alone until after shutdown then went to P00 manually.
IIRC it is a 1204 alarm; the G&N book says if ave-g on to continue. It keeps updating the state vector but locks out the DSKY.

I just tried a TLI with your scenario, this time with P15. I am not getting this program alarm and I have never seen it before. Just to rule out any user error, you are entering the TB6 time from the TLI PAD, right? And then you have to enter the cutoff velocity. So not the DV of the TLI burn like you put in the EMS counter, but the 35000 something ft/s.
 
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