Flight Question Initial heading

[exe-c]

Hi there!
Just a small question - how to pick my initial heading direction. I know that for ISS it must be 162', but i totally don't know what's about Mir.

So my question is - how to calculate initial heading degree and achive a perfectly aligned with target orbit after ascent.

 

[Moach]

it really depends on where you're launching from... if your launch site has a higher latitude than the target's inclination*, you probably won't be able to launch in direct alignment... for instance, KSC to MIR won't happen without a plane adjustment burn, same goes for the Moon...

in any case - Launch MFD is your buddy! :thumbup: - check the hangar for it, it's really simple to use, with a flight director and all...

*(in equatorial frame)

 

[exe-c]

Thanks alot!

I've downloaded Launch MFD, but didn't find any documentation. Is there any tutorial, or documentation on that MFD?

 

[Iberville]

Where did you download it from? Because from the recommended addons from the forum, it contains plenty of doc and tutorials inside the folder.

 

[Enjo]

Oops. Indeed, I forgot to include the documentation... Will be fixed in the next release.
For now - http://www.elwico.pl/~ender-sz/orbiter-pdf/pliki/LaunchMFD-doc.pdf

 

[Thundersnook]

Oops. Indeed, I forgot to include the documentation... Will be fixed in the next release.
For now - http://www.elwico.pl/~ender-sz/orbiter-pdf/pliki/LaunchMFD-doc.pdf

Wonderful! I just want to ask for it! Thanks!

 

[Enjo]

Wow! Does it mean that somebody will read my documentation !?

 

[Thundersnook]

Wow! Does it mean that somebody will read my documentation !?

LOL! xD Well ... i just saved it on my hard-disk ... maybe I'll read it .. sometime ... xD
(Great documentation! )

 

[Tommy]

Launch headings for the ISS are 42 degrees or 138 degrees, not 162. I also recommend LaunchMFD, but if you want to learn to do it the "hard" way, I suggest getting the DGIV from Dan's Orbiter Page (check the quicklinks). In it's manual it gives the formula for calculating launch headings - including step by step instructions for using the DGIV's built in calculator to do it.

 

[insanity]

http://www.orbiterwiki.org/wiki/Launch_Azimuth

 

[exe-c]

Thanks alot for all theese answers!

A small additional question - as far as i know the optimal launch heading is 90'. Is there always a 'window' that allows launching at 90' heading, or in some cases we can only use pre-calculated headings?

 

[PhantomCruiser]

This is my layman's answer... Because, well, I'm a layman...
90 degrees might be considered to be optimal because it will allow you to take the earths rotation into consideration as you develop horizontal speed. Vertical velocity (straight up) will get you to space, but you won't stay there. Horizontal speed is what gets you to orbit. So, launching at 90' can "help" quite a bit, particularly when using "real" rockets.

 

[Tommy]

90 degrees is the optimal heading IF the 90 degree heading also results in the lowest relative inclination. This will only be true if the target's Inclination is equal to or less than your starting latitude. For instance, in a launch from KSC to an equatorial orbit, 90 degrees is best. No other heading will give you less RInc, and you get the full velocity caused by the Earth's rotation for free.

For Inclinations higher than the starting latitude (ie, KSC to ISS) you will want an inclination other than 90 degrees. You don't get the full "headstart" from the planet's rotation, but the loss there is much less than the cost of a plane change once in orbit.