Any tips to docking in Kerbol-orbit?

[lukaszett]

Hi guys,

I'm planning to build a space station in kerbol orbit but as of yet I didn't even came close to docking.

Are there any tips or tutorials?

Edited September 14, 2013 by lukaszett

[Scarecrow88]

The principles are the same as docking in Kerbin orbit. The only problem I found was that a 'close' encounter was usually some distance away compared to the 5km or so that many recommend when making a normal rendezvous. My suggestion would be to put your station together in Kerbin orbit, and only move it to a Kerbol orbit once it's ready.

[Dooz]

well Docking in Interplanetary Space is Very hard I Never have Attempted it Heres What its like Getting a Encounter With a Planet that is Very very very Small No gravity Well Make sure to put alot of Deltav On your Module

[Hannu]

There are problems with accuracy. Probably due to float-datatype or otherwise bad computing algorithms. You should adjust velocity several times before rendezvous. Let's say 3 days, 1 day, 12 h and 3 h. Typically you have very large delta v and you must start braking burn before you even see the distance marker of target. Little use of mathematics helps to solve right start for burn. Mechjeb is a great help, if you are not against it. When you are in range of several kilometers, do not use time warp. It can move crafts kilometers relatively to each other. Therefore docking takes much time and is boring. There are also some erratic influences, so that you should actively watch rendezvous parameters. I recommend that you should not intentionally plan dockings on solar orbit, but occasionally KSP's orbit calculations make large errors when you return from Jool and if you try to optimize delta-v near theoretical values, you may need rescue missions.

[Rage097]

well Docking in Interplanetary Space is Very hard I Never have Attempted it Heres What its like Getting a Encounter With a Planet that is Very very very Small No gravity Well Make sure to put alot of Deltav On your Module

This burns my eyes...why are you doing this to us?

But yeah, Docking in interplanetary space is waaaay more effort than it's worth.

[Respawn]

I have done a couple of interplanetary dockings and it's just like docking in kerbin orbit, except the distances is higher.

I've found that when in loading range of your target don't use time warp,

as your target will tend to jump around several km when physics is unloaded.

Use physics warp instead or just be patient.

[Captain Sierra]

The only question I have for the OP is where in interplanetary space are you attempting to dock? For example: a low kerbol orbit for a sun observatory station would be much easier compared to trying to dock outside of Moho orbit. Then again, docking is not the hard part here, it's the rendezvous. If you can get within 5-10 km or so and cancel relative velocity, you are almost done. Getting that rendezvous is a real b**ch.

[Sirine]

my advice is dont do it. too tedious.

[Sirine]

try search for a youtube，or even picture. you cant find one.

[ArmchairGravy]

Make sure your RCS is balanced. Have docking ports come out the ends, not the sides. Dockees face south, dockers face north. .2 m/s is plenty fast. Work with one axis at a time. Good luck!

[NeoMorph]

The secret to docking is when you get close (ie less than 2km) you zero out your relative velocity and then aim towards the target and burn... then when you are getting closer but off target you zero relative velocity again and then burn towards the target again.

The secret really is relative velocity. Oh and putting your camera in Chase View. Oh yeah and balancing your payload's RCS system (I wrote a tutorial to do that).

Check my sig for tutorials on various stuff.

Edited September 14, 2013 by NeoMorph

[lukaszett]

@NeoMorph

Umm... docking itself isn't my problem. Getting close to the station is my problem

[Kasuha]

If you never tried docking, you should probably practice docking on Kerbin orbit first, then move on to Kerbol orbit. I don't see any particular reason why should they be any significantly different except for greater distances.

Regarding docking:

Step 1: put the two things on orbit around the same thing (Kerbin, Kerbol, whatever). Drive one and set the other one as target

Step 2: match their inclination by adding and executing maneuver at either intersection node. You need the angle to be 0.0

Step 3: if the object you're docking to is ahead of you, go on lower orbit to catch up. If it is behind you, go on higher orbit to wait for it.

Step 4: when you're sufficiently close, add a maneuver and play with it until you get intersection or minimum distance sufficiently low. It's good if it happens at very close angle

Step 5: after you find such point and execute the maneuver, add another maneuver at exactly the meeting point and match the two orbits as exactly as you can. Execute that maneuver

Step 6: From now on you switch from map chase to navball chase. Check your navball, there are your prograde and retrograde marker and the two markers for direction towards and from your target. Notice that when you accelerate in a direction which is not straight towards prograde or retrograde, these two move around the navball. You need to push your prograde marker on top of the "toward target" marker. You can do so by either accelerating in a direction which on the opposite of the target marker than where your prograde marker is, or by decelerating in a direction which goes from target marker through the prograde marker. In either case you don't want your relative speeds to be very high, it should be less than 1% of your distance.

Step 7: When you are up close, kill the velocity and select the target plate as target and your plate as "control from here". If you can rotate the target, rotate it towars you and just go forward (at a reasonable speed). If you can't or don't want to rotate your target, you need to put yourself above the target spot visually.

Notice that in Kerbin orbit everything appears to rotate around the axis perpendicular to the orbit. To get rid of the target plate escaping, you can rotate it so it is perpendicular to the orbit (i.e. aims straight at south or north on polar orbit) and then place yourself against it. You don't even need to accelerate towards the target in that position, orbital mechanics will push you together as your orbits intersect.

In Kerbol orbit I assume the orbit matching part will be a bit harder and may require many tweaks to get you together close enough so you see the target in space. The docking itself should be easier though, as orbital mechanics play way less role there so no target rotating away will take place.

[lukaszett]

As I said: docking itself isn't a problem. I can dock in Kerbin orbit.

Btw: that's the closest I came:

[maltesh]

If you're in solar orbit, at 86 km planned separation, you are far more than close enough to start ignoring the map screen and begin the closing phase. In solar orbit, you can start doing that from tens to hundreds of thousands of kilometers of distance, on the timescales of a solar orbit, spacecraft move in effectively straight lines over periods of days to weeks. You need to manually switch to Targeting mode on the navball, and use your engines to maneuver your prograde relative-velocity indicator onto your target-direction marker from there.

[Kasuha]

As I said: docking itself isn't a problem. I can dock in Kerbin orbit.

Btw: that's the closest I came:

[image]

That's quite good. At that position you can just turn on RCS and start playing with it to check which direction makes the distance smaller. If it skips too much, just let the ship come closer. Otherwise you can nudge the intersection close to zero using short RCS bursts.

Also add a maneuver at the intersection and match the two orbits with it (apoapsis, periapsis and position, just overlay the two orbits with it). You can probably do that using navball too but it will tell you beforehand how long that correction will be and will leave you close to zero relative speed.

Edited September 14, 2013 by Kasuha

[Sirine]

@lukaszett

I try it, I know. You try it you know. It is impossible to get closer!!! "They" don't try it "they" don't know. The game and the scale size calculation can't work out.

[lukaszett]

I did it! =)

(well I had to cheat for about 300 m/s delta-v but it should be doable without cheats.)

I'll probably start a challenge about docking in interplanetary space.

http://www.fotos-hochladen.net/uploads/sucess2s8khjnumg.png

[Kasuha]

Congratulations!

[Technical Ben]

I'll try setting up a solar probe (no idea if I have the DV for it right now) and video an attempt at a rendezvous. Both manual and MechJeb assisted.

[JiWint]

There are 2 ways.Brute one,and maths one.If you don't use maths,(just like me) use the brute way.Wait until your target comes closest to you,then launch off,get in orbit around kerbol,and burn to your target!

[Sirine]

@lukaszett You did it. congratulation (without the mono-probe gas....).

@JiWint The closes is ...85km away?...when you try to catch up....it float aways...like...2000km away? And gaining like 1000km/seconds...

You guys who think you can do it...PROVE IT!!! Uncut Video only! I don't believe in picture s-h-i-t...

I can HyperEdit it to anywhere I want...With just a few click.

Edited September 14, 2013 by Sirine

[Kasuha]

You guys who think you can do it...PROVE IT!!! Uncut Video only! I don't believe in picture s-h-i-t...

Okay. I tried it. And I docked two ships on slightly inclined circular orbit between Moho and Eve in some hour and half real time. It may feel slow but I'm still a newbie to KSP, only started about two weeks ago. And the ship was not very well balanced for that purpose either, every time I used RCS it started spinning and rolling.

I admit it's tough to bring the intersection point close from far away, the game seems to have some precision problems. But apart of that everything went smooth.

I started from Kerbin and achieved elliptical orbit with periapsis gently intersecting the target orbit.

First maneuver was to bring both to the same plane.

Second maneuver was to lower apoapsis so they come reasonably close after one orbit (that would not be necessary if I planned the start of the second ship more accurately, I just started at random time and on first intersection they missed each other by some 1/5 of orbit)

Third maneuver was to fine-tune that meeting (to about 2000 km).

Fourth maneuver was to put the two orbits on top of each other.

And then I just navballed the two ships together. When they were still too far apart I was checking their meeting point and distance in the map because it was updating correctly.

I don't have a video or pictures because I don't care if you believe me or not. It is possible and it is not hard. I have much worse problems landing on Mun than I had with this.

[Sirine]

I dont believe this. sorry.

[greg12]

Here some docking in one vid. feel free to fast forward because it is 30min but it has

1. first ship launched to 75km circular orbit

2. timed launch of the second ship

3. docking

4. reentry and landing

here: http://www.twitch.tv/greg1277/c/2932970