Launching to Mir

[pandadude]

From the KSC is tricky. How can you work out what launch heading to take? I know there is a launch MFD, but I struggled with it and honestly prefer to work stuff like this out myself.

My question - would now (look at the pictures) be a good time to take off, and if so, what heading should I follow? BTW I know I would take off when the left MFD shows that RInc is best, but that picture is just before such a time would occur. I followed the instructions on the DG-IVs computer for calculating launch heading to achieve a desired inclination, and came up with about 45degrees. Does this sound about right. I know it would take up a lot of fuel to get there because I'd have to reduce the RInc once in orbit, but is this way of launching the most feasible? Is it even possible to get to Mir in the DG-IV with the medium setting for fuel? Or is there an all together more efficient way of getting to Mir than simply launching from KSC and then changing my Inc once in orbit? Thanks once again, maybe soon I can stop asking questions and start answering them. If there are any good tutorials feel free to just link them if it saves you having to explain it.
Pics:

 

[TSPenguin]

I think what will help you most (and save you your alignment burn) is taking off at the right time.
Look at the MapMFD. When the orbit of Mir intercepts with your position, you can take off directly in the plane of Mir. If you wait for the right time you can even launch and directly dock with mir before you even have made half an orbit.

Of course there are mathematical finesses to what is the optimum. But I can tell you, that when you launch at the time the screenshots where made, you chose the least optimal time

Also I think, that align planeMFD is only usefull once you really are in orbit. IMO it should be completely useless sitting on the ground.

Happy Orbiting

 

[pandadude]

Haha so I chose the worst time to launch? I guess my logic was that Mir's orbit path 'matched' mine as closely as it would at any time. Oops!
So basically, I should wait until its orbit takes it over the KSC, and then I should launch in a specific heading? I think it was about 45 degrees.
And I thought the Align MFD was useful for fine tuning the time you launch. Once the RInc has decreased as much as it will, you should launch then, shouldn't you?
I haven't really tried out much with docking with Mir, but that works for me with the ISS which is very easy to get to by comparison.
Thanks for the fedback (you Germans are pretty smart ), I'll give it another shot right now.

 

[Urwumpe]

The inclination of Mir is not 51.6° Equatorial, so 45° should be very far off. Looks more like you need to launch almost polar.

 

[TSPenguin]

Just remember: While you are sitting on the ground, you have no real orbital path. All you do is follow earth rotation. No instruments in orbiter are equiped to deal with this except those who contain launch calculations. (And even those usaly work backwards, calculating the launch data from your desired orbit).
I highly recommend Orbital Operations as a great tutorial to understand how it all works together and learn, well..., orbital operations.

Happy Orbiting

edit: Urwumpe, take into account his goal is not to launch at that moment, his goal is to launch a little bit more efficient.

 

[Urwumpe]

The ideal launch time is just a few seconds before the orbital plane passes over the launch site. Launch MFD has a very good calculation about this aspect.

 

[Woo482]

the other day I was trying to dock when the target was above my launch site and that worked quite good (apart from me doing the wrong kind of burn when I wanted to align planes)

 

[ar81]

You need to wait until orbit passes almost on top of you (Tn smaller than 450 in Align MFD), and calculate launch azimuth and use that azimuth as heading. I do not remember the formula.

 

[pandadude]

I don't know the formula for working out a launch heading, but I just took a stab at 10 degrees. As it turns out, I wasn't far off. I think a heading of about 15 degrees should be pretty much spot on. Even launching at 10degrees heading, during the launch I just changed my heading slightly and managed a RInc of about 3. And that is pretty easily corrected later on at a pretty low cost in terms of fuel. I'm not sure how I got 45 degrees, I just followed the instructions in the DG-IVs checklist and thats what I got. That has never really seemed to work for me though.

Once again, thanks for the help.

 

[Urwumpe]

pandadude: The formula is very simple, as long as you don't correct it for Earths rotation.

Launch MFD can calculate this VERY accurate, you should try it.

 

[pandadude]

Ok maybe I'll give Launch MFD another chance, I think the first time I tried it I rushed through reading the documentation and didn't really understand it.
All I remember is like a compass at the bottom of the MFD that started giving me various warnings even if I just changed my heading ever so slightly.

 

[Urwumpe]

All I remember is like a compass at the bottom of the MFD that started giving me various warnings even if I just changed my heading ever so slightly.

female voice: "After 250 NM, yaw 1° left"

 

[Enjo]

All I remember is like a compass at the bottom of the MFD that started giving me various warnings even if I just changed my heading ever so slightly.

Sorry for making my female instructor so precision demanding. I made her keep more silent in the newest version. You could disable those warnings with SND button... or have them back hehehehe.

Seriously, if you have any feedback about the MFD, then I'm all ears.