rendevousing advice

[jevry]

hello. i could probably use some advice with rendevousing with other crafts.

i have done a succefull rendevous mission once now but did take multiple tries.

i get the part now its important to get close and then match speeds or else orbit wont match and you will simply drift away later on.

but mostly getting close and matching speeds at the right time is kind of difficult.

atm my career world spams my mission list with rescue from low-medium orbit  missions probs due to the techs i chose to unlock so i will need the advice to get more efficient in this task

also about when to launch in the cases you start while landed. i already learned that launching when target is overhead you are already too late

 

note that i do not use informational mods. and am not planning yet on getting mods yet as i 1. feel that is the lazymans way of doing things and 2. i do not know enough about them yet to feel comfortable to use them (for example game and mod updates and their influence)

[Superfluous J]

Try my approach and rendezvous tutorials on YouTube. I also have one for Docking in the same series.

As to the rescue contracts, you get so many because you are accepting them. The game gives you more of what you tell it you like. Stop doing them, and they'll start to go away and be replaced by other contracts. It helps if you look at them and don't accept them, and helps more if you actually decline them.

Spoiler

 

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[bewing]

But if you turn down the rescue contracts -- later on you will wish that you had done them.

Those free kerbal employees are worth ten thousand times their weight in kash.

 

[Some Kerbal]

As per brewing above, I would do rescues until you are sick of them. One - the practice. Two - free kerbals

[Hodari]

2 hours ago, jevry said:

but mostly getting close and matching speeds at the right time is kind of difficult.

atm my career world spams my mission list with rescue from low-medium orbit  missions probs due to the techs i chose to unlock so i will need the advice to get more efficient in this task

also about when to launch in the cases you start while landed. i already learned that launching when target is overhead you are already too late

 

note that i do not use informational mods. and am not planning yet on getting mods yet as i 1. feel that is the lazymans way of doing things and 2. i do not know enough about them yet to feel comfortable to use them (for example game and mod updates and their influence)

If you're not worried about being especially efficient about it(and for stock game at least, you really don't need to be), then just do the following:

1.  Launch your craft into orbit.  Any stable orbit will do for now. 

2.  Set the other vessel as target.

3.  Warp to either the ascending or descending node and burn anti-normal/normal in order to match the target's inclination.

4.  Warp to your periapsis or apoapsis and burn until your orbit intersects the target's orbit in at least one point.  By now, you should see a 'closest approach' marker on your map.

5.  If the target is behind you in its orbit, you'll want to put yourself into a higher orbit so you take longer to go around and it can catch up to you.  If it's ahead of you, you want to be in a lower orbit so you catch up to it, if possible(but don't forget that you need to stay high enough to not enter the atmosphere, so if you can't go any lower, you'll have to put yourself into a higher orbit instead and wait until you circle all the way around relative to the target). 

6.  From your closest approach point, do a burn to put yourself into the appropriate orbit described in step 5.  Watch the separation distance shown at that closest approach point.  The greater the difference between your orbit's height and the target's, the faster you will catch up to it, but you'll also be moving faster relative to the target when you do approach it and need more dV to slow down.  There's usually no rush, so don't be afraid to spend several orbits slowly approaching your target like this.

7.  Keep time warping ahead to just after you pass the closest approach point and watch what the distance will be for your next orbit.  When it shows you getting reasonably close to the target on your next orbit(or passing it altogether), burn either prograde or retrograde to adjust this distance and try to get it as close as possible(ideally under 1km).  You might also need to do a slight correction burn on exactly the opposite side of your orbit to get it as close as possible.

8.  Once you have the close encounter set up, warp ahead to a couple minutes before that encounter.  You should now be close enough to see the target and will no longer need map mode.  From here on, switch to the craft view and you can do everything visually or with the navball.

9.  Switch the navball to target mode and point retrograde.  Burn your engines until you get your relative velocity down to under 10m/s. If you're planning to actually dock, click on the port you want to use and select 'control from here'. Now set SAS to point towards Target and turn on your RCS.   All remaining maneuvers can be done with that. 

10.  Maneuver so that the prograde marker is exactly aligned with your target marker(meaning that you are now moving directly towards the target). 

11.  (Optional)If you're planning to dock, switch to the target vessel, select the docking port on that ship and point it directly towards the other ship as well, then switch back to controlling your other vessel.

12.  Keep SAS set to point at target and continue adjusting the prograde marker to keep it aligned with the target marker as you approach.  Also as you get closer, reduce your approach velocity so you don't overshoot (or worse yet, collide with) the target.  I usually keep it to 10m/s when I'm within 1km of the target, 2-5m/s when within 100m, and all the way down to 0.2m/s for the last few meters.  If you're not actually docking and just doing a rescue contract, you can stop 20 meters or so away and just EVA across from there.

 

If you're trying to be more efficient about things, or course you'll want to try to wait until the target is going to be passing overhead and launch into the right inclination to begin with as well as timing it so you end up close to the target right when you get into orbit.  But since time doesn't matter much and it's easy to make a ship with plenty of dV to spare, this isn't required. 

For targets in equatorial LKO, I'd say launch when the target is over the ocean just before the continent the KSC is on and you should be fairly close.  The exact spot will depend on your ascent profile, so adjsut accordingly from there.

[Spricigo]

What 5thHorseman said. (thanks for all your videos btw) 

You may also keep the images from This guide around for quick reference. 

[Waxing_Kibbous]

This video made it click for me. The next thing is the EVA to the rescue ship, my early rescue attempts had many lights and lots of ladders to grab Now I just make sure the rescue craft is aligned so the hatch faces the stranded vessel and the rescue craft is pointed up in the orbit so it matches the Kerbal EVA alignment. These little steps will make life easier.

 

Edited December 29, 2016 by Waxing_Kibbous

[jevry]

15 hours ago, bewing said:

But if you turn down the rescue contracts -- later on you will wish that you had done them.

Those free kerbal employees are worth ten thousand times their weight in kash.

 

i don't as i don't want to lose the rep it costs to turn away a mission. what ussually works for me is do the ones i can do and hope contracts have dissapeared replaced by easyer ones when i come back.

 

but for the rest thx evryone. the videos have cleared things up for me now. (i am one of those guys who learns the most from seeing.)

rendevousing should less fuel and time consuming now. especially while being in orbit.

[steuben]

Probably mentioned in the vid links. But... don't approach your target at more than 5 m/s when you're less than 1 km from the target. I've ignored that advice. On a perfect approach at 17 m/s the results were spectacularly terminal for both the station and the new module.

[Superfluous J]

1 hour ago, jevry said:

i don't as i don't want to lose the rep it costs to turn away a mission

This is, for the most part, an invalid fear. Even declining the entire available pool won't ding your reputation in any appreciable way.

[GoSlash27]

17 hours ago, Some Kerbal said:

As per brewing above, I would do rescues until you are sick of them. One - the practice. Two - free kerbals

And 3 it pays well. I mean... just getting experienced kerbals for the cost of the mission is worth it, but then they *pay* you pretty handsomely for doing it! It's like taking candy from a baby who hates candy.

Best,
-Slashy

Edited December 29, 2016 by GoSlash27