Flight Question Stock Atlantis launch azimuth

[BioEgo]

Hi! I've recently started to experiment with the space shuttle, and before getting into the complexities of the varius Fleets or SSU, I decided to try my hand with the stock orbiter Atlantis.
Since the main problem with the shuttle is the very limited dV launching into the correct azimuth is paramount to complete a randevous and docking with the ISS.
When fliyng DG style ships I usually considered even a 2° mis-alignment to be good enough, but I've seen that that's too much for the shuttle!!
To calculate the right launch azimuth I usually used a spread-sheet I made out with the equations found on the OrbiterWiki, until I found out about LaunchMFD (same results, but the ability to have them in game is definitely interesting:thumbup. The problem is that even using those tools and setting the resulting azimuth in the atlantis/launch script I almost consistently end up a couple of degrees misaligned with the ISS. I tried to reduce the gap by launching a bit before the intersection between the orbit of the ISS and the Cape, but with poor results. Taking a second look to the Orbiter2010 tutorial "Space Shuttle to ISS", I noticed that not only the launch was made 180-190 seconds before intersection, but also the azimuth was set to 139deg even though LaunchMFD suggested a 137.2deg azimuth: the difference between LaunchMFD and effective launch azimuth being about the same difference I get when launching based on the MFD:hmm:
Since I suppose the decision of adding those two degrees to the launch azimuth wasn't just made by chance, can someone explain me how how to correctly calculate the azimuth for the shuttle or give me some pointers to documents or books I could use to understand how to do it? lease:

As a second (but definitely less important) question: when trying to launch without using the script, during the initial roll how can I know I'm in the correct position to begin pitching and end up in the correct azimuth?? I know it must be something very stupid but I can't really get it right:embarrassed:: since the shuttle takes off with its nose up the compass readings are quite useless until I pitch up, but then its too late to change course.....or probably I'm just missing something somewhere!

Bye and thanks,
BioEgo

 

[N_Molson]

Correctly calculating a launch azimuth is not something trivial...

But the formulas are on OrbiterWiki.

Also, some launch windows are better than others. Be sure that the trajectory of the ISS passes right over your head (using MapMFD). The closer, the better.

In theory, you should launch your spacecraft X seconds before T0, where X is the "half orbit velocity time", or the time that your spacecraft needs to accelerate to the half of it's final orbital speed. Which depends of the trajectory you fly. I think .

Hopefully, trial and error is something we can afford in Orbiter.