Docking - I just don't get it

[lugge]

Folks, I post this with huge rage.

Just wasted two hours in docking again. I just don't get it.
After years of playing this game, thousands of launches, hundreds of rendezvous and a lot of docking, I still have problems.
Sometimes, it's easy to me, sometimes, like now, it just wont work.  Everytime I think I finally got it, the next time it will not work at all.

Simple scenario: interplanetary mothership in orbit, separate launch for crew, supplies and landing vessel for landing at destination.

 

Yeah, well, it's dark.
That doesn't make things easier.

So, what did I do?
- rendezvous (easy)
- switch to mothership and align it till the desired docking port is pointing exactly "down"
- switch back to crew vessel and align it so my docking port is point exactly "up"
- set other docking port as target
- control my vessel "from here" (from docking port")
- activate RCS, play with translation keys
- profit

Well, no. No profit. Sometimes it's easy, this time it didn't work and after typing this post (in rage) I have to go outside and so some running before my neighbors wonder what I'm shouting all the time.

I watched a lot of videos and I thought I got it.
Just use translation keys, don't even look at the camera view because the navball is all I need.
Play with translation keys to adjust my prograde marker to match the target marker.

But how am I supposed to do this?
Everytime, the keys behave differently. OK, this is due to the vessel's orientation. Sometimes "n" will make the craft go left instead of down, then I have to adjust camera and / or vessel orientation.
A good docking manouveur for me is like gambling.

Come on, what are your ideas? Consider the situation in the screenshot. What am I supposed to do now?

 

 

[AngryKitty]

Quite honestly can't see a thing in this screenshot. Do you have a daylight version?

[klesh]

36 minutes ago, lugge said:

Come on, what are your ideas? Consider the situation in the screenshot. What am I supposed to do now?

 

Hi,

Don't worry.  Docking is definitely one of those "get it" kinds of things.  Once it clicks, all of the content you've watched to help you understand will make sense.  Some is just more effective at communicating it ceonceptually to you.

 

In your above screenshot, take it again with either sunlight showing things, or the ambient light setting turned up.  It can be found in settings.  Its really hard to tell whats going on.

[lugge]

Sure I have.

 

Quote

 

Hi,

Don't worry.  Docking is definitely one of those "get it" kinds of things.  Once it clicks, all of the content you've watched to help you understand will make sense.  Some is just more effective at communicating it ceonceptually to you.

 

In your above screenshot, take it again with either sunlight showing things, or the ambient light setting turned up.  It can be found in settings.  Its really hard to tell whats going on.

 

It's not that all the explanations don't make sense. They totally do and about half of the time docking is no problem.
Check navball, use translation keys to match prograde marker with target marker.

However, the keys sometime behave totally weird, depending on vessel orientation.
Sometimes, I just have no clue how to control make craft and end up hitting random keys till it "clicks".

Edited April 30, 2018 by lugge

[CrashyMcCrashFace]

Switch the camera mode to "locked" and it will give the correct orientation, and then move the camera to behind the ship (behind the control from here docking port). The rotation will be correct and the same each time.

Edited April 30, 2018 by CrashyMcCrashFace

[HebaruSan]

47 minutes ago, lugge said:

Play with translation keys to adjust my prograde marker to match the target marker.

This is only a good idea if your target marker is already straight ahead for your craft. I.e., your orientation is correct and your position relative to the target is correct. Otherwise you'll end up zooming in diagonally, which makes it more difficult. To get them lined up, you want to overshoot the target marker till to moves to the center of the navball (and then hastily thrust in the opposite direction to zero out your velocity).

47 minutes ago, lugge said:

But how am I supposed to do this?
Everytime, the keys behave differently. OK, this is due to the vessel's orientation. Sometimes "n" will make the craft go left instead of down, then I have to adjust camera and / or vessel orientation.

Are your RCS blocks aligned with the center of mass? If not, then using them for translation can cause torque, which might be what you're seeing.

47 minutes ago, lugge said:

Come on, what are your ideas? Consider the situation in the screenshot. What am I supposed to do now?

Another option is to use the target marker mode of SAS for both craft instead of normal and antinormal. This can be a bit more forgiving as any lateral drift is automatically accounted for.

[Snark]

On 4/30/2018 at 8:15 AM, lugge said:

However, the keys sometime behave totally weird, depending on vessel orientation.

This is not the case.  The keys always do exactly the same thing, relative to the ship, regardless of vessel orientation.

There are some issues that can cause confusion, sometimes:

• If you're actually looking at the camera view of the ship... this can confuse you.  Because, for example, K will always thrust to the ship's starboard (right) side, which might be up, down, left, right, or whatever on your screen, depending on how it's oriented.  So unless you can train your eyeballs and brain to do the necessary mental gymnastics to reorient your perception in line with the ship (which some folks can do more easily than others)... you may need to just force yourself to ignore the camera and focus on the navball.  Because the navball is golden:  it will always, always show you things relative to the ship, which is what matters for the control keys.
• Make sure that the navball is in target-relative mode (i.e. it says "Target" and not "Orbit").  This is important, because otherwise the critically important and markers will be completely useless for docking.
• Be aware of the significance of "control from here".  If your docking port is on the front of your ship, pointing in the same direction as your probe core or command pod, then this isn't so much of an issue.  But it's anywhere else-- e.g. mounted on the side of your ship, pointing sideways-- then you need to make sure that your "control from here" point is set to the docking port, and mentally orient yourself to that docking port since that's what the navball will now show.
• Make sure your RCS thruster placement makes sense.  If you've got a long ship with all your RCS thrusters at one end... it's going to be unmaneuverable, because trying to translate sideways will cause it to rotate all over the place.  Either put your RCS thrusters in a ring around your CoM "equator", or (for long skinny ships) put a ring at each end.
• Use "fine control" when docking (toggle this on via caps lock).  This does fancy magic with your thrusters, giving them proportional thrust that automatically compensates for CoM placement.  It won't help you if your RCS thruster placement is catastrophically bad (e.g. if you have a long skinny ship with the thrusters all at one end)... but if your placement is even approximately reasonable, this works wonders.

Here's an illustrated docking tutorial I wrote a while back, which you may find helpful.

[klesh]

Ahh, okay.  I had just edited the previous screenie to see what was happening, it had a simpler situation compared to what you've posted now.  Its okay, I can explain this one too.

 

I'll presume foreground ship is what you're flying and background is the target. 

1) You've got the dockingport target targeted, control from here on your port.  Good.  Your relative movement is 0.

2) The target is effectively "behind" your docking port, so first thing is SAS on, RCS on, Press Shift to go to fine RCS controls, Press N to back yourself "downward" to be below the ship.  Retract the lower Gigantor panel on the motherhip for safety.  Back away until you are perhaps 10-20m below the ship and press H to cancel your backward motion and come to a stop relative to the docking port.

3) Using RCS while holding yuour ship's direction, press J and see what happens.  It will push your ship to your ship's "left", but unless you have sorted out your orientation, you dont know what that movement will do relative to your target.  L is the opposite of J, so you can use it to stop that movement and come to a halt again, or if J made you move away, you can use L to make you move closer.

4) Repeat step 3, but this time use I and K.  This will be the other 2 directions relative to the target.

5) The goal of steps 3 and 4 is to allow you to slide your ship under the target docking port while keeping it pointed in the same direction as you see in your screenshot.  Once you are close to being directly under it and, say, 20m away, AND have sorted out IKJL and how those buttons will move you, THEN you have the info you need to for final approach and docking.

6)Once you've gotten under the target port, and you're in target mode on the navball as you are, you will see the target icon on the navball.  In fact, you will use that icon when sliding under the target port to know when you're right under it.  When you are directly under it the icon will be smack on your forward-pointing-dot (pointed at the horizon on your screenshot).  You want to be directly under the mothership's port, pointing right at it, at a 0m/s relative speed.

7) Once there, use H to move forward at 0.5m/s or less.  Once you initiate that forward movement, the prograde marker will show up, and since you'll be pointing at the target , the prograde marker will overlap it.  Due to the orbit both the ships are in, the longer it takes to make this last 20m, the more adjusting the prograde marker with IJKL will be needed to keep it overlapping the target icon perfectly.  When they are perfectly overlapping AND your ship-forward-dot is in the center its telling you a) my control from here point -my docking port- is pointed directly at the target docking port. b) my entire ship is moving directly forward at the target docking port.  If during the final approach the prograde marker slides away from the target icon, you use only IJKL to slide it back.  That takes some getting used to, but with the orientation you discovered in steps 3 and 4, you should already understand how to make your very minor corrections here without panicking.

 

[lugge]

 

I don't know whats happening today, this is the worst docking I ever did.

I try to only use the navball. I thought I'm good with navball because rendezvous or target-landing are no problem.
Is my navall orientaded correctly? Should I change my orientation?
The target marker is showing up every now and then but it is moving just at the edges of the navball. No way I can catch it with my prograde marker.
Is this a sign of wrong navball orientation?

As you can see, my navball in the screenshot has no marker at all.

[Snark]

11 minutes ago, lugge said:

Is my navall orientaded correctly? Should I change my orientation?

Ding ding ding.    Your ship is pointed wrong.  (On the plus side, your relative velocity to the target is nicely zeroed, and you've got your navball in target-relative mode, so those are good.  It's just your ship orientation that's the problem.)

Looks to me like you're not even vaguely pointed in the right direction.  I'm assuming that you've already got your "control from here" point set to your docking port, right?

In that case, you want your docking port to be pointed at the target, right?  In that case, your marker should be dead-centered on your navball.  That's how you know you're pointed at it.  Since it's not even showing, that means you're not pointed even close to it.

I mean, from your screenshots, I think your docking port is located on the top of the lander can, i.e. at the right end of the ship in the screenshot you've just posted.  Look at it-- your ship isn't even slightly pointed towards the target.

So you should use your WASD keys to rotate your ship until your docking port is pointed at the target.  Then start using your RCS to maneuver to dock.

[HebaruSan]

18 minutes ago, lugge said:

As you can see, my navball in the screenshot has no marker at all.

Yup, that's the problem. It's not a question of navball orientation though. Your relative position is wrong.

Press 'n' to go backwards until you see the target marker again, then use ijkl to move it to the center of the navball, then try again.

[Snark]

14 minutes ago, HebaruSan said:

Yup, that's the problem. It's not a question of navball orientation though. Your relative position is wrong.

Actually, unless I'm mis-reading his last screenshot, I think that actually orientation is the problem.

My impression is that his docking port is located on top of his lander can, at the far right side of his ship in that most recent screenshot.  It's pointing off to the right.  It needs to be pointing at the target ship.

Or am I all confused and missing the point, here?

[lugge]

OK so I got it wrong all the time.

This is what my navball now looks like:

 

@Snark I always thought the ports have to match orientation relativ to the orbited body.
Thus why my motherships points "down" (relativ to Kerbin) and my vessel points up. Then I used translation keys to fix x, y and z coordinates.
Because when I do this, translation keys will not let my craft move "diagnoal" (relativ to Kerbin).

Seems I got it very wrong.

Now I orientated my craft to the target as you can see in my navball.
maybe I'm more lucky now.

 

Update:

I just got a contact, however, it was more by luck then by skill ;-)

But they didn't dock. Seems I have more problems here.
I placed the docking port at the side of the hitchikers. According to forum, this may lead to problems because docking ports must never clip but always placed on attachment points.
Otherwise, they wont work properly.

If so, I just have to get this ship rebuilt and up again... :-((

Edited April 30, 2018 by lugge

[HebaruSan]

4 minutes ago, Snark said:

Actually, unless I'm mis-reading his last screenshot, I think that actually orientation is the problem.

My impression is that his docking port is located on top of his lander can, at the far right side of his ship in that most recent screenshot.  It's pointing off to the right.  It needs to be pointing at the target ship.

Well, look at the target docking port. It's pointed directly leftwards in the image, just as the main craft is pointed rightwards. Assuming that you're right about the active port, that means the ports directly oppose one another, so the orientation is fine, but they're translated several meters apart. Rotating the ship is an option, but then you have to either un-rotate it again later, or rotate both ships. Approaching it as a translation problem avoids those complications.

[lugge]

5 minutes ago, HebaruSan said:

Well, look at the target docking port. It's pointed directly leftwards in the image, just as the main craft is pointed rightwards. Assuming that you're right about the active port, that means the ports directly oppose one another, so the orientation is fine, but they're translated several meters apart. Rotating the ship is an option, but then you have to either un-rotate it again later, or rotate both ships. Approaching it as a translation problem avoids those complications.

@HebaruSan
Yes, I always handled it this way since I "learned" it this way years before.

Let one port face "left" (or up...) and let the other one face "right" (or down...) relativ to Kerbin and solve the situation by translating the craft.
In this approach every translation key will move the prograde marker in exactly one direction acrross the navball (e.g. hit n, marker will go down).

Otherwise, the marker will move diagonal.

However, @Snarks approach sounds reasonable. In my approach, I my end up with no target marker, like in my first screenshots.

However, now I have to check if the clipping-docking-port bug is still there.
Seems I have to use a radial attachment point because KSP doesn't like ports directly on hitchiker cans.

[Snark]

13 minutes ago, HebaruSan said:

Well, look at the target docking port.

Oh.  Duh.  Yes, of course, you're exactly right.  I managed to miss that in the screenshot, I assumed he'd already gotten his target lined up and just needed to point at it.

So yes, in this case his target ship was pointed wrong, too.  Neither ship was pointed towards the other.

As you quite rightly point out, this can be treated as a pure-translation problem.

@lugge, in case this conversation between @HebaruSan and me is confusing you, and you're trying to figure out which of us is right-- we both are.  We're just describing different ways to dock, because there's not only one correct way to do it.

• HebaruSan is optimizing for "don't rotate anything", i.e. do everything with translation.
• I'm optimizing for "rotate them to point at each other, then translate".

Neither way is "right", it's a question of what works best for you.  I tend to prefer my way because, in my experience, what's hard and tricky (especially in the dark) is taking a ship and flying it around the target to put it in the right spot.  To me, that's a navigation nightmare.  I far prefer rotating both ships so that their docking ports are pointed at each other.  That way, the actual translation part of docking becomes dead simple:  just head straight towards the target, with at most just a little bit of lateral correction as it approaches, in case it wasn't quite lined up to start.  Because to me, "rotate the ship until my port points at the target" is a much easier, simpler operation than "fly my ship around in 3D space to put it in front of where the target happens to be".

That's just how I do it, though.  Other people have different techniques, and HebaruSan's way also makes perfect sense.

20 minutes ago, lugge said:

 

@Snark I always thought the ports have to match orientation relativ to the orbited body.

Huh?  No, why would you think that?  The orbited body is completely irrelevant.

I mean, if you're trying to put a cap onto a pen... you need to have the pen and the cap lined up with each other.  It doesn't matter whether the pen is right-side up or upside-down or pointing north, south, east, or west.  The orientation of your house is irrelevant.  All that matters is their positioning relative to each other.

20 minutes ago, lugge said:

(relativ to Kerbin)

Kerbin doesn't matter in this case.  It's completely irrelevant.  You might as well think of it as pretty background wallpaper.

Using the pen and cap analogy, here's a summary of the different ways HebaruSan and I are suggesting that you dock.

Imagine that you're holding a pen in your left hand, and the pen's cap in your right hand, and you want to get the cap onto the pen.

• HebaruSan's way (if I may take the liberty of putting words in his mouth-- hope I'm not getting it wrong):  Rotate the cap until its hole is parallel to the pen's point.  Then move your right hand until the cap is right in front of the pen's point.  Then push the cap onto the pen.
• My way:  Without moving the location of either the pen or the cap, rotate each one until it's pointing at the other.  Now push the cap onto the pen.

These ways both work.  They're just following a different set of steps.

20 minutes ago, lugge said:

I placed the docking port at the side of the hitchikers. According to forum, this may lead to problems because docking ports must never clip but always placed on attachment points.
Otherwise, they wont work properly.

No, that's not the case.  They work just fine if you put them anywhere.  That's why they're radially attachable.  You just need to make sure they're not clipping something (which they won't, if you simply put a docking port on the side of a Hitchhiker).

20 minutes ago, lugge said:

If so, I just have to get this ship rebuilt and up again... :-((

No, you shouldn't have to do that, unless I'm missing something else.  Something else is going on.

[Greenfire32]

Things to do to make docking easy:

1)  Put both vessels in a North/South orientation. This eliminates "drift" as your vessels will rotate with an axis instead of against an axis.
2) set the docking port you intend to dock WITH as "control from here" and make sure you select the port you intend to dock TO as your target.

3) Put the camera so it's facing straight into the back of your port outward (imaging the top of your docking port is a cockpit and the "back" of the port is an engine, put your camera in a postition where you would be looking "up" the exhaust)

4) LOCK the camera and NEVER touch it. This prevents you from learning that certain keys move certain ways and then confusing yourself when you move the camera and find that your brain still thinks "I should move a certain way with these certain keys," but your eyes don't confirm that because the ship isn't moving relative to the camera.

5) celebrate with cake because now you're docked.

[Snark]

2 minutes ago, Greenfire32 said:

1)  Put both vessels in a North/South orientation. This eliminates "drift" as your vessels will rotate with an axis instead of against an axis.

Could you elaborate on this?  As long as both vessels are parked close to each other at zero relative velocity, how they're oriented relative to the planet doesn't make any difference, does it?  How does this help in any way?

[Kryxal]

5 minutes ago, Snark said:

Could you elaborate on this?  As long as both vessels are parked close to each other at zero relative velocity, how they're oriented relative to the planet doesn't make any difference, does it?  How does this help in any way?

Assuming it's an equatorial orbit, then any difference in position when aligned for docking will not result in off-axis drift over time.

[Greenfire32]

14 minutes ago, Snark said:

Could you elaborate on this?  As long as both vessels are parked close to each other at zero relative velocity, how they're oriented relative to the planet doesn't make any difference, does it?  How does this help in any way?

Sure. It's easy to match two vessel's relative speeds, but it's much harder to match two vessel's relative rotations. Think of it like this: there's two people walking on track. One person is using the inner most lane and the other is using the outermost lane. They are maintaining a position where they remain parallel to one another. On the straight-aways, both people find it really easy to keep pace. The outtermost person will have to walk at the same speed as the innermost.

But on the corner bends, the outtermost person will have to walk, or even lightly jog, to maintain their position relative to the innermost person while the innermost person will also have to walk slower.

Now that's not too difficult on it's own, but now let's say that both people are only ever allowed to face one direction the entire time they walk the track (meaning at some point both people will be walking backwards, sideways, normally, sideways in the opposite and backwards again). This is the rotation.

Now the straight-aways are easy again, but the corners get really tough. In addition to having to walk faster or even jog, the outermost person will have to rotate at a slower rate, while the innermost person will not only have to walk slower, but rotate at a quicker rate.

There are no straight-aways in orbit. You're constantly on the corners. And because of the limitations of the game, you can only ever control  one vessel at a time, meaning you cant control both lanes of the track.

By aligning both ports into a North-South orientation, you 100% eliminate the need to adjust rotation and can focus solely on translation. You don't need to rotate slower or quicker, you only need to walk faster or slower.
------
TLDR: by aligning yourself and your target properly, you eliminate "drift" from either vessel. 99% of the difficulty of docking comes from "drift." Get rid of it, and you can do it in your sleep.

Also, North/South really only works for equatorial orbits. You would have to determine your "neutral" rotation around a planet for different inclination orbits, however the concept remains the same.

Edited April 30, 2018 by Greenfire32

[HebaruSan]

11 minutes ago, Snark said:

• HebaruSan's way (if I may take the liberty of putting words in his mouth-- hope I'm not getting it wrong):  Rotate the cap until its hole is parallel to the pen's point.  Then move your right hand until the cap is right in front of the pen's point.  Then push the cap onto the pen.

Heh, I'll go ahead and endorse those words after the fact.  Note that the "pen" might be a space station much more massive (or wobbly) than the cap and therefore inconvenient to rotate. But I'm not necessarily advocating either approach; I noted the "rotate both" option in my first reply. I'm just trying to build on what the OP is already doing, which starts with the old "orient normal and anti-normal" strategy.

7 minutes ago, Snark said:

Could you elaborate on this?  As long as both vessels are parked close to each other at zero relative velocity, how they're oriented relative to the planet doesn't make any difference, does it?  How does this help in any way?

It's a subtle effect, but it has to do with how the difference in the orbits affects the crafts' relative movement over time. A normal/anti-normal orientation means that the difference between the orbits is just (extremely slight) inclination, so somewhere you have an ascending node and a descending node, and simply waiting will inevitably bring the two craft together at one of those points. Whereas if you go for radial/anti-radial then one of the craft has a (very slightly) higher semimajor axis, and therefore slower orbital period, and therefore they'll tend to drift apart rather than come together. I think prograde/retrograde is like a compromise, with not quite the problems of radial, but still a bit more painful than normal. If you dock within a minute or two of rendezvous it won't matter, but if you're up there for multiple orbits, it can be a minor help.

[HebaruSan]

2 hours ago, lugge said:

Everytime, the keys behave differently. OK, this is due to the vessel's orientation. Sometimes "n" will make the craft go left instead of down, then I have to adjust camera and / or vessel orientation.

I think I understand what you meant by this a little better now.

'n' thrusts backwards, always. But if you're watching the nav ball, 'n' will move the velocity vector away from the center. This is because the velocity vector shows a combination of your forwards and sideways velocities, and the center of the navball is always forwards. When you decrease your forwards velocity (assuming you are currently moving forwards), your sideways velocities get larger by comparison, so the marker moves more towards the sideways directions. (If you are moving backwards, then all of that is reversed---'n' will move your retrograde velocity vector towards the center of the navball, because it makes you move backwards even faster.)

If you are looking at the navball and wanting to move your velocity vector around, only use ijkl. This will behave consistently. Only use 'n' and 'h' to control whether you are moving towards or away from your target.

[Snark]

On 4/30/2018 at 9:59 AM, Greenfire32 said:

TLDR: by aligning yourself and your target properly, you eliminate "drift" from either vessel. 99% of the difficulty of docking comes from "drift." Get rid of it, and you can do it in your sleep.

On 4/30/2018 at 9:59 AM, HebaruSan said:

It's a subtle effect, but it has to do with how the difference in the orbits affects the crafts' relative movement over time. A normal/anti-normal orientation means that the difference between the orbits is just (extremely slight) inclination, so somewhere you have an ascending node and a descending node, and simply waiting will inevitably bring the two craft together at one of those points. Whereas if you go for radial/anti-radial then one of the craft has a (very slightly) higher semimajor axis, and therefore slower orbital period, and therefore they'll tend to drift apart rather than come together. I think prograde/retrograde is like a compromise, with not quite the problems of radial, but still a bit more painful than normal. If you dock within a minute or two of rendezvous it won't matter, but if you're up there for multiple orbits, it can be a minor help.

Oh, is that what was meant?

I'm aware of that effect... but I tend to ignore it, because in my own experience it's neither necessary nor sufficient for docking, because although the effect is real, it's so minuscule that it gets dwarfed by other factors that render it basically irrelevant as far as I can tell (like that myth about what hemisphere you're in determining which way water swirls down the drain).

Additional thoughts in spoiler because I'm probably getting sufficiently verbose that it won't really help @lugge with the problem at hand.

Spoiler

Regarding "not necessary":  If you've got two vessels that are parked within a few dozen meters of each other, and they're initially at zero relative velocity... then any drift effect that's induced by their actually being in slightly different orbits is tiny.  Yes, if you just parked them there and left them sitting there for an hour without doing anything, it would cause drift.  But if you're docking, it means you're moving around at least one of the ships anyway, and the speeds involved in docking are so much higher than this type of drift that it's basically just lost in the noise.  A typical docking scenario looks like:  1. Make rendezvous, kill orbital velocity.  2. Align.  3. Dock.  Steps 2 & 3 put together take a minute or less, and any "drift" caused by orbit variation is, in my experience, centimeters at most.  It's simply a non-factor.

Regarding "not sufficient":  Unless you're using some kind of specialized navigational mod, it's basically impossible to get to true zero relative velocity anyway.  The navball's relative velocity indicator won't read any value smaller than 0.1 m/s, meaning that it's really hard to make your relative velocity lower than 3 cm/sec or so.  In practice, there's always going to be that last bit of drift that's due to this 10 cm/sec uncertainty in your actual relative velocity.  And that drift is going to shove your ship out of place no matter where you've got it parked.  And, in my experience, that "velocity uncertainty" drift is going to dwarf the "orbital positioning drift", to the point that the latter becomes irrelevant.

My own preference is to ignore the supposed orbital-drift problem, therefore.  In my experience, not only is it small enough to be indistinguishable from other sources of error, but also, docking velocities take place at much higher speeds anyway (e.g. 10 to 30 cm/s) so that it's simply not a factor.  Any two ships left parked near each other, in any relative position, anywhere, are going to drift significantly on a timescale of tens of minutes.  It's why "park A next to B, long term" is not something one does in KSP.  If you want things to stay together, they need to be stuck together.

So I tend to advise people not to care about this, mainly because if you do want to follow an "align north/south" strategy, this eliminates some otherwise useful degrees of freedom and requires the player to precisely fly their ship to the correct relative (x,y,z) coordinate in 3D space, relative to the target.  Which is certainly doable, but in my experience is more challenging to a newbie than "just park anywhere you like close to the target, and then rotate them to point at each other."  The "north/south" strategy seems to me to be making things more difficult, rather than less.

@lugge, the TL;DR to this little debate here is that there are some folks who contend that orienting ships north/south helps, and others who say it doesn't matter (or may even make things harder).  I happen to be in the latter category myself.    As for which side is "right", well, about all I can advise is try it both ways and see what works better for you.

 

On 4/30/2018 at 10:14 AM, HebaruSan said:

If you are looking at the navball and wanting to move your velocity vector around, only use ijkl. This will behave consistently. Only use 'n' and 'h' to control whether you are moving towards or away from your target.

^ @lugge, this.

Just wanted to make sure you don't miss this key bit of advice, amongst the flood of information here. 

Just to reiterate-- you may want to take a look at the illustrated docking tutorial I mentioned.  It's not a video, it's an explanation-with-pictures, and shows how the navball behaves as you maneuver for docking.  Section 5 may be of particular interest to you.

[lugge]

OK, I re-did the mssion.

This time, I strictly followed @Snarks approach.
And it was easy as pie, can't believe it :-)
Does this mean all my previous docking attempts in the last years were merely based on lucky instead of knowledge? ;-)

However, I still have issues getting the two ships docked.
The ports touched each other, then my craft flipped away.
I rebuilt the mothership, this time with attachment points to make sure the docking ports do not clip into something, like, the hitchikers.
Don't know what's happening here.

Today I did a test with the senior docking ports (at the end of the mothership), they worked just fine.

Strange thing: even when the two ports are very close to each other, the distance readout says 7,9m.
But in the picture, this does not look like 7,9m.

And yes, I selected the port as target ;-)
Any ideas?

[Snark]

10 minutes ago, lugge said:

And it was easy as pie, can't believe it :-)

Great! Glad it worked out. 

10 minutes ago, lugge said:

However, I still have issues getting the two ships docked.
The ports touched each other, then my craft flipped away.
I rebuilt the mothership, this time with attachment points to make sure the docking ports do not clip into something, like, the hitchikers.
Don't know what's happening here.

That's... odd.  No clue what's going on.

To repeat, it shouldn't matter that your target docking port is mounted to the side of a Hitchhiker.  I do that all the time.  You don't need the attachment points, seriously.  Whatever your issue is, that isn't it.

A couple of questions:

• How fast were you going when you were on the approach?  i.e. what was the relative speed?  Was it nice and slow (e.g. under 0.3 m/s), or was it something crazy-fast (like 1 m/s)?
• Did the docking field engage, or not?  (i.e. when they got within a meter or so of each other, could you see that they were then drawn together like magnets?

10 minutes ago, lugge said:

Strange thing: even when the two ports are very close to each other, the distance readout says 7,9m.
But in the picture, this does not look like 7,9m.

And yes, I selected the port as target ;-)
Any ideas?

Did you select your ship's own docking port as your control-from-here point?  Because if you didn't, then it may be controlling from another point (e.g. the center of your lander can, or whatever), which could affect the displayed distance.