Launch azimut ?

[Joker]

Hello !

I'm working on a custom scenario with the Apollo 11 VAGC and I can't change the launch azimut.

I tried V78 during the prelaunch but not working. I've also tried to change it in octal but not working too. I tried with LV GUIDANCE on IU and CMC and happens the same result.

Is someone as any idea about this issue ?

Thanks a lot !!!

 

[indy91]

The launch azimuth in the AGC only changes the platform alignment of the IMU. The LVDC is controlling everything about the launch, not the AGC.

The LVDC has a mission specific polynomial, time into launch window versus launch azimuth. At T-17 seconds the LVDC will check the current GMT and compare it to the GMT when the launch window begins. So the only way to get a different launch azimuth is to launch later than planned. In NASSP there currently is no capability to stop the countdown. So the way we have been doing late launches is to just take the T-4 hour prelaunch scenario and change the MJD in there. For Apollo 11 that is:

Date MJD 40418.397222333

almost at the top of any Orbiter scenario. That MJD corresponds to 4 hours before the nominal launch time. Just change that to a later time and you will launch to a different direction. That is all that needs to be done to launch to a different azimuth.

In the RTCC MFD there is a LVDC page under utilities. That page can calculate the launch azimuth the LVDC is going to use, so that you can input it to the AGC with V78 and get the right IMU alignment for launch.

Note that this method only works for missions that have the full set of LVDC guidance presettings. Those are Apollo 8, 11, 14 and (with limitations) Apollo 17. The other missions can only launch at the nominal time to the nominal launch azimuth right now.