How to determine what orbit direction you will be thrown into in encounters?

[panzer1b]

Well this is an issue ive come up with recently, how do i decide well ahead of the actual encounter what direction ill be thrown into when i get the ecounter.

Ive wasted tons and tons of dV trying to reverse the direction (its doable on very high orbits around weak gravity fields like duna, but its still alot of dV thats wasted for nothing). So can someone here give me some tips or tutorial/link to one that explains how to get into a counterclockwise/clockwise (depending on what i need to do) orbit around a body, and also it would be nice to get some help optimizing orbital maneuvers. Also, is it possible to reverse a orbit using a mun's gravity slingshot or something? I dont like to throw fuel away at things liek orbital reversals, so if possible, please tell me how to get my orbit right ahead of time.

Edited December 7, 2014 by panzer1b

[Reactordrone]

Once you have an encounter you can select focus view of the targeted body and zoom in. Small trajectory adjustments can then be made to correct your path to whatever side (or top) that you want to come in at. With interplanetary manoeuvres I usually aim straight at the planet and then adjust once I'm within the sphere of influence.

[Kryxal]

In your settings.cfg file, there are CONIC_PATCH_DRAW_MODE and CONIC_PATCH_LIMIT, you can change those to show more transitions and show them in different formats ... or add a mod like PreciseNode (which does a fair bit more too).

[psyper]

Once you have an encounter you can select focus view of the targeted body and zoom in. Small trajectory adjustments can then be made to correct your path to whatever side (or top) that you want to come in at. With interplanetary manoeuvres I usually aim straight at the planet and then adjust once I'm within the sphere of influence.

This. Once you get an encounter left click on where the target planet or moon is and choose 'focus view' on the context menu - this will change your view to the planet or moon itself and will show you where your orbit will come in at. If you want to go counter-clockwise (normal prograde orbit) you want to come in on the right hand side when looking top down outside of kerbins orbit (behind the planet or moon) or the left hand side when coming inside of kerbins orbit (in front of the planet). If you reach the planet or moon's SOI and you're on the wrong side then its easier to correct your direction there by placing a manoeuvre node a couple of minutes in front of your craft and then either pulling retrograde (backwards) which will slow your ships speed toward the target so it moves across your path or pull the radial out maker to pull your direction to the right (reverse this when heading in to the inner solar system). This will use up little dv compared to doing this once in orbit.

However, if you finally do find yourself in a orbit opposite to what you want or you need to change your orbit for whatever reason you use far less dv / fuel if you do the change in two manoeuvres - set a node down at your periapsis and pull the anit-normal or normal markers (pink ones) until your orbit is in a polar orbit (90 degress to your path) - this will also have the effect of sending your apoapsis out away from the planet/moon - don't worry about this unless its out side its SOI - if this is the case just pull on the retrograde marker until it drops back in - once you have a 90 degree orbit execute it and then put a manouver node in at your ap marker and do a similar thing there too to bring your orbit going the opposite way - you can now use the retrograde marker to bring your orbit in to your desired orbit and then circularize as normal - although you're doing several manouvers they will use less dv than just turning around and gunning it until you're going in the opposite direction.

Edit: left click will give you the menu to focus view on the planet or moon you click on them - not right

Edited December 7, 2014 by psyper

[panzer1b]

This. Once you get an encounter right click on where the target planet or moon is and choose 'focus view' on the context menu - this will change your view to the planet or moon itself and will show you where your orbit will come in at. If you want to go counter-clockwise (normal prograde orbit) you want to come in on the right hand side when looking top down outside of kerbins orbit (behind the planet or moon) or the left hand side when coming inside of kerbins orbit (in front of the planet). If you reach the planet or moon's SOI and you're on the wrong side then its easier to correct your direction there by placing a manoeuvre node a couple of minutes in front of your craft and then either pulling retrograde (backwards) which will slow your ships speed toward the target so it moves across your path or pull the radial out maker to pull your direction to the right (reverse this when heading in to the inner solar system). This will use up little dv compared to doing this once in orbit.

However, if you finally do find yourself in a orbit opposite to what you want or you need to change your orbit for whatever reason you use far less dv / fuel if you do the change in two manoeuvres - set a node down at your periapsis and pull the anit-normal or normal markers (pink ones) until your orbit is in a polar orbit (90 degress to your path) - this will also have the effect of sending your apoapsis out away from the planet/moon - don't worry about this unless its out side its SOI - if this is the case just pull on the retrograde marker until it drops back in - once you have a 90 degree orbit execute it and then put a manouver node in at your ap marker and do a similar thing there too to bring your orbit going the opposite way - you can now use the retrograde marker to bring your orbit in to your desired orbit and then circularize as normal - although you're doing several manouvers they will use less dv than just turning around and gunning it until you're going in the opposite direction.

ill try that next time im actually stuck in a bad orbit. It is most effective though if you do it as far away from planet as you can right as then the velocity change requirement is lower?

Also, could someone link me to a tutorial for maximum optimized rendezvous in terms of dV (be it a planet or a ship). Im sure they exist somewhere, but ive gotten to the advanced stage of ship design and orbit stuff, and id kinda like to be able to squeeze the most out of any given amount of dV, so anything could be useful.

[psyper]

ill try that next time im actually stuck in a bad orbit. It is most effective though if you do it as far away from planet as you can right as then the velocity change requirement is lower?

Also, could someone link me to a tutorial for maximum optimized rendezvous in terms of dV (be it a planet or a ship). Im sure they exist somewhere, but ive gotten to the advanced stage of ship design and orbit stuff, and id kinda like to be able to squeeze the most out of any given amount of dV, so anything could be useful.

Close to the planet gives you an effect known as the oberth effect where you'll get a lot more 'bang for your buck' but I think that only counts for retro and prograde manoeuvres (anyone care to back me up or contradict me on this?) - normal and anti-normal (up and down) isn't really affected by how far away you are - so whatever orbit you're in it doesn't matter where you make the 90 degree turn - I choose periapsis (close to the planet) so that you have less chance of getting pulled in to the planet while making the manouver (when you perform it you should see your path go in to then back out of the planet as it turns around).

Tutorials:

Scott Manley is pretty much the go-to guy in ksp - any of his videos are pretty good - for moon rendezvous go for this one:

That should link to the video with the whole tutorial series as a playlist so use them as much as you like.

[Heagar]

There are two rules if you want to change an orbit with minimum DV requirements:

• direction changes you make as far as possible away from you target -> is valid for a planechange too (midcourse correction burn).
  For that you mark your destination as target and burn at the AN (Ascending Node) in the direction of 180 degrees and at the DN (Descending Node) in the direction of 360/0 degrees of the currently orbiting gravitational source (star/planet/moon).
  
• speed changes you make as near at the target as possible
  

To see if you are on the right side (90 or 270 degree course for example) you can look in map view on the estimated course after leaving the SOI of the target.

For example a course to Mun.

If you have an orbit around Kerbin on the 90 degree course and plot an manouver node you can see that the ejection course is:

• prograde to muns orbit (can go strait out of Kerbins SOI) = you are on an 90 degree course at the target
  
• retrograde to muns orbit (maybe even in an figure eight pattern back to Kerbin = free fall return) = you are on an 270 degree course at the target
  

For fine adjustments you can switch the view to your target and look at the estimated course inside the SOI of the target.

[Taki117]

Simple explination: if you are on the day side as you come in you are in a clockwise orbit. If you are on the night side it's an anticlockwise orbit. You want to make your adjustment as far out as possible and burn radially (the blue markers on the navball) to change which side you are on. This is best done just inside the SoI boundary.

[Red Iron Crown]

Close to the planet gives you an effect known as the oberth effect where you'll get a lot more 'bang for your buck' but I think that only counts for retro and prograde manoeuvres (anyone care to back me up or contradict me on this?) - normal and anti-normal (up and down) isn't really affected by how far away you are

You are correct. Prograde and retrograde burns benefit from the Oberth effect and are best made at the highest speed possible (usually periapsis); radial and normal burns do not benefit from Oberth and are best done when moving as slowly as possible.

To the OP, small radial/normal burns are the best method for fine tuning your approach. The further from your target you make those adjustments, the less dV they will cost but the harder it is to be precise. Using RCS or thrust-limited engines allows better precision. I usually do a coarse course adjustment about halfway through the transfer, then a final adjustment once I enter the target SoI.

[Kryxal]

As a refinement, if you have a large component of normal/anti-normal to your adjustment, you'll probably want to aim for about a quarter of the orbit ... further than that and you're possibly losing effectiveness on that vector.

[Mesons]

In your settings.cfg file, there are CONIC_PATCH_DRAW_MODE and CONIC_PATCH_LIMIT, you can change those to show more transitions and show them in different formats ... or add a mod like PreciseNode (which does a fair bit more too).

I highly recommend doing this, and setting CONIC_PATCH_DRAW_MODE to 0 (zero). This will draw your orbit around the encountered body as if you were already in it's SOI, allowing you to easily determine whether you will be heading east or west when you enter, as well as where in the SOI you'll be entering. Trust me (and Kryxal), start here and check out some of those other fancy tips only if this isn't enough for you.

[panzer1b]

Thanks guys for the advice, the conics setitng helps ALOT, while i can do it manually, its alot easier now, and it doesnt clutter up the map view too much (it drawn a little more stuff but why not)