NASSP TEI Error

[jedimaster1214]

Hello all,

Having Issues with TEI on Apollo 11 with the latest builds.

In my scenario, ullage will complete, and the SIVB will ignite for all of about 3 seconds, and then will turn off.

I attached my scenario for context.

Thanks!

 

[indy91]

TLI is what you mean.

You seem to be using the Project Apollo MFD with the LTMFD for the TLI burn. That is no longer necessary and maybe not even possible in the NASSP 8.0 alpha version. NASSP now uses a simulated Launch Vehicle Digital Computer (LVDC++). Some launch scenarios (currently Apollo 8, 11 and 14) come with a fully configured LVDC++. That means the S-IVB is able to calculate and perform the TLI maneuver completely independently. No need to use the PAMFD and LTMFD for TLI at all. There are still remnants of the old IU autopilot, controlled through the PAMFD, so in your case the old IU autopilot and the LVDC++ might interfer with each other and cause the failed TLI.

My suggestion is going back to a scenario before you started using PAMFD for TLI. All you have to do is wait for the S-IVB beginning the TLI sequence on its own.

On the NASSP development side the PAMFD TLI features will probably removed in the near future. That should reduce confusion, it's an outdated feature.

 

[jedimaster1214]

Awesome, thanks for the update.

I guess the provided excel checklists need to be updated as well, because all of them state to use PAMFD & IMFD/LTMFD, and provide the necessary input information.

If the TLI guidance is provided by LVDC++, is it accurate enough to be used faithfully? Is there a different vector/loadout for every supported mission?

 

[indy91]

Awesome, thanks for the update.

I guess the provided excel checklists need to be updated as well, because all of them state to use PAMFD & IMFD/LTMFD, and provide the necessary input information.

Yeah, the Excel checklists are mostly outdated, too. For Apollo 7 and 8 they are already completely replaced by new word checklists more closely resembling the flown checklists. Also, procedures for the full missions are available in the Checklist MFD. The Checklist MFD already supports Apollo 7-11, other documentation for Apollo 9-11 is not available in NASSP yet. You can use the flown flight plan and the generic word checklists you can find in the NASSP Docs folder.

If the TLI guidance is provided by LVDC++, is it accurate enough to be used faithfully? Is there a different vector/loadout for every supported mission?

There is a different loadout (targeting presettings) for each mission. Apollo 11 and 14 are supported because we have the full documentation for these missions. So they use the exact same targeting parameters as those actual flights. Apollo 8 is supported because NASSP 7.0 included full mission support for Apollo 7 and 8. Apollo 9 and 10 will be supported at some point, NASSP 8.0 will support Apollo 7-11. There is a way to update the LVDC++ with new targeting parameters for other missions, using the RTCC MFD. But you don't have to do that with Apollo 11.

The LVDC++ uses the same guidance equations as the real LVDC and it gives pretty good results. A few people have tested it with Apollo 11 and the result is very small midcourse corrections. Works just like the real deal.