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Kickn4fun

Docking Problems

Question

So, I'm having terrible (seeming) issues docking. I have my 2 modules on a perfect line, a closing speed of about 2 m/s, and once i get about 40m away, they just seem to rocket apart from each other. I've spent about 3 hours this morning trying, and I'm going to take a break.

I have spent a decent amount of time getting their orbits to match up, to the point that the 2 encounters are .1km apart, and relative speeds of >5m/s. What else am I missing in trying to dock? This is my first time trying this maneuver, so I'm sure I'm doing something wrong. I've looked up several tutorials, but they all seem to leave me guessing on my own a bit. 

Thanks for help, in advance.

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Posted (edited)

@Kickn4fun It seems like you aren't matching velocities.  The method in Scott Manley's video up above works, but it's a really bad way to do it.

I'm going to post this from what I posted in another thread.  First make sure your velocity indicator says "Target".  If not, click it until it does (you must have a target).

Burn here to "Push" the :retrograde: marker away from you to the :targetretro: marker while decreasing relative speed to the target.

qtCD7S1.png

Burn here to "Pull" the :prograde: marker to the :targetpro: marker while increasing relative speed to the target.

Oq3ti4H.png

When they are perfectly aligned, aim straight at the retrograde markers to simply slow down (relative to the target) as you approach.  You will want to have 0 Target Velocity before getting too close.

IY40WY1.png

Try to avoid doing outside the 5km range (the closer, the better).  If you are going too fast and your mass is high and engine is weak you will have to burn earlier just to have time to slow down, but try to avoid it.  Also the exhaust from your main engines will push the target, so avoid getting too close while they are on.  Once you are there, use RCS to dock (not pictured, those were hacked into orbit for screenshots)

Edited by Alshain
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Ok. Just before closest approach, set the navball to "target", hold retrograde, and burn till velocity is within 0.1m/s.

Point both ships toward each other using target hold (good for beginners) and use RCS to translate toward target. Keep the prograde marker on target marker with I,J,K,L. Do not use the engine! Use H and N  to control speed. Docking should be at 0.1 m/s. As soon as magnets start pulling you visibly, TURN OFF SAS ON ACTIVE VESSEL! Otherwise they will fight each other and not dock.

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Posted (edited)

@Kickn4fun

so it looks all with ships is right! Now 2 tipps if you are near to each other your rcs is your best friend! And you have 2 controll panels

WASD+Shift+Strg is for rotation yaw and pitch and for right left with your Ceneter of Mass (CoM) as axel and for main engine, best one disable the main if you are near and slow. And

IJKL+H+N for translation up down and stear left right, h and n give you the ability to speed up and slow down without turning the ship.

For docking you use best this combination and don't switch to docking mode..

@Just Jim i think this are the medium docing ports and there are allright (smile is seemable(?))

PS i hope we dont overcook here because so many are there:blush:

Urses

Edited by Urses

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can you post a screenshot? Without seeing what's up it's hard to say... but my first guess, based on what you've written, is if they're pushing against each other, then one of the docking ports may be upside down.

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I'm sorry, I must have explained it a little wrong. They aren't pushing each other, they aren't even meeting up. 

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At closest approach, did you match your velocity?

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Posted (edited)

It would be very usefull if you show us a screenshot. Take a screenshot using F1 ingame, the screenshot will appear in .../Kerbal Space Program/Screenshots/.. Upload it to something like imgur and copy the image link to the forum.
Just to make sure, the two docking ports can parent? E.g. they are the same size, the junior can't dock with the normal one. 
Are you playing in stock? or mods.

 

Welcome to the forum btw! :) 

If you're talking about the whole Maneuver tingy, Here's a great video of Scott Manley explaining how to dock.

 

Edited by DrLicor

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Posted (edited)

8 minutes ago, Kickn4fun said:

I'm sorry, I must have explained it a little wrong. They aren't pushing each other, they aren't even meeting up. 

Ahhh.... OK. But so you know, and don't feel bad, docking is one of the most challenging things to learn in KSP.... so don't give up. :)

 

Edited by Just Jim

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Posted (edited)

Hi

3 addotional questions.

1. Play you pure stock?

2. Are you sure the docking nodes are same diameter?

3. Are there build in in right manner?

I ask because on my first docking in real game i manged to try to dock a medium and a junior and the medoum was invards:D

Funny Kabooms 

Urses

PS: pics and/or craftfiles would be beautiful for sure 

Edited by Urses
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6 minutes ago, Urses said:

Hi

3 addotional questions.

1. Play you pure stock?

2. Are you sure the docking nodes are same diameter?

3. Are there build in in right manner?

I ask because on my first docking in real game i manged to try to dock a medium and a junior and the medoum was invards:D

Funny Kabooms 

Urses

PS: pics and/or craftfiles would be beautiful for sure 

1. Yes, pure stock game, no mods. 

2. I habent unlocked different size docking nodes yet. 

3. I'm 'assuming' it's built correctly, the nodes snap-locked into place when I built them. 

21 minutes ago, Brent Kerman said:

At closest approach, did you match your velocity?

No, I wasn't checking that. I'll have to try that.

 

Pics incoming. (was cleaning house..)

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Here's a view of the 2 vessels in close proximity. they get closer, but they move away quite quickly.

Ssm7nL7.png

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You have to match your velocity! Very important! Then you approach the target on RCS. You are just flying by, you have to stop relative to the target before final aproach towards it. And find a newer video, the one posted is from .18, there have been a lot of changes, specifically with SAS.

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Here's my 2 vessels. The command module, and the science lab. The lab still has the last stage of the rocket on it.e53XA1l.pngnw0geME.png

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The problem is they snap lock in both positons! Inside and outside!

Thus means you have the juniors at the moment. The right side for out is the side without the proonged cilinder. If you look precisely you see black smiley there.

Here you see the right position

Spoiler

OYfDVSz.png

And here is the smiley where i talk about:

Spoiler

BqDeE1W.png

As you see on the first one the docking ports have 2 snapnodes and this will provoke some position failures at first attempts.

The most valuable advice for docking will be maybe following.

1. Don't be to fast at first trys, 0,5m/s will be to much to manage

2. Make it step by step. first rotation than tranlsation and vice verse, you need some correktures on first trys

3. if you are below 0,5m range and does all right till than the magnetism will do the rest. if you are there and nothing happens than is something fishy for sure!

and the best one gave you @Just Jim don't give up^^

Try, evaluate, try again!

I hope sth here helps, and if not try to post some pics please.

Funny Kabooms

Urses

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2 minutes ago, Brent Kerman said:

You have to match your velocity! Very important! Then you approach the target on RCS. You are just flying by, you have to stop relative to the target before final aproach towards it. And find a newer video, the one posted is from .18, there have been a lot of changes, specifically with SAS.

So should I match my velocity before i get within 100m? Say, 500-1000?

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Posted (edited)

3 minutes ago, Kickn4fun said:

Here's my 2 vessels. The command module, and the science lab. The lab still has the last stage of the rocket on it.nw0geME.png

If i am not realy blind i think the docking port here IS the wrong way:D

Urses

Can you please get it in near pic?

Edited by Urses

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I usually do it about 50m, but I'm good at rendezvous. I would suggest at about 250m (if you get that close) 

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Posted (edited)

OMG... the navball!!!  Click on the velocity gauge at the top of the navball and switch it to target... that will help you match velocities.

Also, it looks like you're using Docking Port Srs... IMO those are the easiest to accidentally get flipped upside down.

 

Edited by Just Jim

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here's the science lab docking port and the command module port.ki0YnpA.png

qL15VSx.png

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It seems to me your problem is rendezvous. Do you ever come to a complete stop relative to the target?  The navball on the second picture suggests otherwise.

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6 minutes ago, Brent Kerman said:

It seems to me your problem is rendezvous. Do you ever come to a complete stop relative to the target?  The navball on the second picture suggests otherwise.

No I don't. I think that's the big problem I'm having, is the rendezvous. 

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OK, docking ports look right.... That ruled out, my next guess would also be matching velocities and then moving in slowly... I tend to match as soon as I'm within visual range (2.2km) then move in slowly, and correct if and when needed.

4 minutes ago, Kickn4fun said:

No I don't. I think that's the big problem I'm having, is the rendezvous. 

OK, try this... target the ship you're aiming for, and then the docking port itself when you're close enough (within 200m) and make sure the navball is set to target. Then turn your ship retrograde and throttle up slowly until your velocity reached 0.0m/s. At this point your velocity is now matched up with your target ship. Now you can turn and aim the ship at your target and then slowly move in closer. 

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1 hour ago, Urses said:

Hi

3 addotional questions.

1. Play you pure stock?

2. Are you sure the docking nodes are same diameter?

3. Are there build in in right manner?

I ask because on my first docking in real game i manged to try to dock a medium and a junior and the medoum was invards:D

Funny Kabooms 

Urses

PS: pics and/or craftfiles would be beautiful for sure 

1. Yes, pure stock game, no mods. 

2. I habent unlocked different size docking nodes yet. 

3. I'm 'assuming' it's built correctly, the nodes snap-locked into place when I built them. 

Do you guys think I should drop the current science module, and try again? I'm thinking maybe remove one of the large fuel tanks, and make a small stage just to maneuver the craft into position. 

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Posted (edited)

4 minutes ago, Urses said:

@Just Jim i think this are the medium docking ports and there are allright (smile is seemable(?))

You're right, I should have said something when I saw one up close  :)

Edited by Just Jim
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2 hours ago, Alshain said:

@Kickn4fun It seems like you aren't matching velocities.  

Same impression there. Both @Alshain and @Urses explained the docking procedure,  choose one explanation and follow it. 

There is two common methods to match velocities(in both cases use navball in target mode) :

1) wait for closest approach and burn retrograde until relative speed drop to 0.0 

2)match direction as soon as possible,  gradually reduce the relative as you come closer to the target (less than 20m/s for each 100m of distance works well) 

 

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