Docking (I'm sure this has been answered)

[giddonah]

Ok. I'll admit it. I'm frustrated. Docking is what made me give up the game last fall. I've been back since the .24 update and it's awesome, but I'm at my same old problem now. ....ing docking is a huge pain in the ass and I don't get it.

I have two craft within 20m of each other. I've actually managed to bump them into each other even. The claw is supposed to make this easier since I can "dock" with a craft that doesn't have a docking port? I'm not getting it.

I've watched the videos, I've read the posts. It just doesn't make sense. Is this possible without RCS? Do I need to just abandon the flights that are currently 20m apart and just use docking ports? Do I need RCS engines and tanks on every rocket?

This is supposed to work. I've seen videos of this working.

I don't use any mods. Mostly because I don't have the time to invest into what mods will work and won't work with each update, and I don't want to start using a mod that will break with an update. So I play the vanilla game. WTF. I just want to transfer some fuel. I'd like to build a space station some day, but if I can't even "dock" two rockets, that seems impossible.

Someone please help me. I don't get it. Docking mode? Nothing happens! I go back and forth wasting tons of fuel just to get them close to each other, and they just bounce off and now I'm scrambling and wasting even more fuel. I sure would like this to work.

Edited August 6, 2014 by giddonah

[Sirine]

Perhaps, post your persistent.sfs or quicksave.sfs.

We could help you to identify the problem. Pretty quick.

[Wanderfound]

We need more detail. Screenshots, preferably. What speed, what angle, what size ship, what mods, are your docking ports installed correctly, etc.

If you have the docking ports lined up, the ship in line with the port, you approach at less than 0.3m/s and turn off your SAS when you get close, it should connect.

RCS makes it easier, but it isn't absolutely necessary. Similarly, aids like the Lazor Docking Cam aren't necessary, but they do simplify things.

[giddonah]

Thanks for the help, but I'm not using any mods. Zero. No docking ports, I'm using the claw thing. No RCS on the ships I'm attempting with.

I realize mods might make this easier, but with updates I hesitate to run anything that might break. Plus, it's possible without mods.

My approaches are under 5m/s, but they're not under 1m/s, I'm not that good. I end up burning in circles if I try to approach too slowly.

I approach slowly, then the orbit changes and then all of a sudden I'm getting further away. So I burn towards the target. Orbit changes, and I'm moving further away... rinse and repeat. Bash head on desk.

Can I attach the .sfs directly, or do I need to link to it?

Edited August 6, 2014 by giddonah

[Vlk]

There was a bug where the magnetic force of the docking ports did not activate. But i think it happened only after you docked at least once.

20m seems far, for me. The docking ports have to meet perfectly (less than 1 m). Like here (15:00):

It is possible to do this without rcs, but for the first time, rcs can be useful. For the rcs to work reliably, you have to balance them out around the center of mass. (Be careful: the center of mass might move away if you use up fuel. (You can design a ship where it stays in one place))

[giddonah]

I'm not using docking ports.

I repeat: I'M NOT USING DOCKING PORTS.

I think I'm just going to abandon both flights and rebuild the ships using RCS and docking ports.

[Scarecrow88]

You ask about docking, and then tell us you are not using docking ports. I'm confused.

[giddonah]

There's a claw thing that you can grab stuff with. It can be used instead of docking ports. You just float up to another rocket and "grab" it, and you're "docked". I don't get the details though, because I've rammed that thing into another rocket and it didn't grab at all. And by "rammed", I mean at 4m/s.

Which is why I'm inclined to just give up and use RCS thrusters and docking ports.

[Laie]

I never used the claw, but heard that it needs quite some force to activate. So if you are using the claw, try to ram the other ship with some gusto, like 2 meters per second.

If you are actually docking, you need to be more gentle (less than 1m/s, preferably no more than 0.2) and you have to match the docking ports pretty much dead center. The navball is a great aid in this. It is desirable for them to be parallel as well, but a 20° tilt will still work out more often than not as long as you manage to hit the other ships' port.

RCS isn't stricly necessary, but... Let me put it this way: If docking is like riding a bike, docking without RCS is like doing handstands on a bike.

[Sirine]

register a free account at www.. Upload, and post the link here.

[Simes]

There's a claw thing that you can grab stuff with. It can be used instead of docking ports. You just float up to another rocket and "grab" it, and you're "docked". I don't get the details though, because I've rammed that thing into another rocket and it didn't grab at all. And by "rammed", I mean at 4m/s.

Which is why I'm inclined to just give up and use RCS thrusters and docking ports.

Apologies for asking what might be obvious, but: is the claw deployed?

[LordFjord]

...

My approaches are under 5m/s, but they're not under 1m/s, I'm not that good. I end up burning in circles if I try to approach too slowly.

I approach slowly, then the orbit changes and then all of a sudden I'm getting further away. So I burn towards the target. Orbit changes, and I'm moving further away... rinse and repeat. Bash head on desk...

This sounds familiar to me from my 1st docking attempts. (the close misses, circling)

- you are already 20m close, so you are almost there already. Is this a stable 20m or the closest you got to it? I assume its your closest approach and you are not in a stable 20m away position.

- lets say you are still several km away.

- make sure that your navball speed indicator is switched to target mode - then it will show your relative speed and trajectory to your target.

- Find your retrograde marker (the green X). Aim at it and give some thrust until you get your relative speed down to 0 m/s. -> now you are in a stable position relative to your target.

- Now point your claw towards the target - I assume its at the front of your vessel - give a little thrust and try to crash into your target very gently.

- if you seem to miss it - repeat the last step. Try to kill your relative speed to the target and try again.

- happy grabbing and don't panic

[Wanderfound]

My approaches are under 5m/s, but they're not under 1m/s, I'm not that good. I end up burning in circles if I try to approach too slowly.

5m/s isn't docking, it's ramming. If you can't get it down to below 0.5m/s you've got no chance. Ideally, you want to be moving at 0.1m/s at the moment of contact.

See http://forum.kerbalspaceprogram.com/threads/89294-Rondevousing-ness-ity?p=1326300&viewfull=1#post1326300 for how to do it.

[DrMonte]

I never used the claw, but heard that it needs quite some force to activate. So if you are using the claw, try to ram the other ship with some gusto, like 2 meters per second.

If you are actually docking, you need to be more gentle (less than 1m/s, preferably no more than 0.2) and you have to match the docking ports pretty much dead center. The navball is a great aid in this. It is desirable for them to be parallel as well, but a 20° tilt will still work out more often than not as long as you manage to hit the other ships' port.

RCS isn't stricly necessary, but... Let me put it this way: If docking is like riding a bike, docking without RCS is like doing handstands on a bike.

I would suggest quite opposite. Try more gentle way. 4m/s might be far too high. Try same speeds as the docking ~ 0.2m/s. The angle of claw attachment is also important. Try aiming to the center of the part (like some big fuel tank).

p.s.

Also the obvious - is the claw armed?

[diomedea]

Some good sugggestions were already given. But I feel something still missing.

1) RCS. Those are your friend when you need to make precision maneuvers, and docking certainly qualifies as such. Is it possible to dock without RCS? Yes, but requires a lot more skill, a vessel able to turn fast and with engine able to deliver very tiny amounts of thrust. RCS must be properly positioned, when used in translation mode their collective thrust vector has to be the closest as possible to the Center of Mass of the vessel, if used in rotation mode the pivot point closest to CoM.

2) Closure speed. No need to ram your target. Docking ports only work correctly at low relative speed, the claw works with some more umph but still will grab if touching the target at just the slightest of speed. A high speed will most probably make you bounce, and send your target spinning. Better to avoid.

3) Claw: it grabs if the surface to be grabbed on the target is at a low angle to the claw axis (best if perpendicular). Won't grab if angled too much. So, choose you approach so to come at a perpendicular angle to your target. Also good to aim for the center of mass of the target, but that is required only to maintain mass aligned with your vessel main axis (e.g. in case you want to push your target afterwards).

[Russoft]

Once you've activated the claw, point it at the other ship and slam into it. Unlike docking ports, it tends to need a bit of speed. As for approaching slowly and having the orbit change, just learn to keep your velocity vector pointed at your target on the navball. Learn how to burn to correct for misalignment. Then you won't burn circles around the other craft but slam right into it.

[NecroBones]

I've found the claw to be a bit picky about how it makes contact. It needs more incoming velocity than docking ports. For instance, with ports, you can approach at about 0.1-0.5 m/s, but the claw seems happier closer to 2-3 m/s. But it also really wants to touch a flat surface, perfectly perpendicular. Try to find the flattest surface on the target and approach right into it. The approach needs to be straight... if you're moving diagonally, the claw will probably want to bounce off.

Also don't forget to make sure the claw is deployed first.

And really, RCS is your friend here. You don't need it, technically, but doing any sort of docking without RCS is a more "advanced" method.

Edited August 6, 2014 by NecroBones

[Greenfire32]

Things that will help you with either the claw or a docking port:

1) RCS. For beginners and for more advanced users, even, RCS is an absolute must. You simply cannot make the fine tune adjustments and directional changes without it. Docking without RCS is more of a "challenge" than "proof of a master docker."

2) Whether with the claw or with a docking port, ALWAYS line your target/ target port up with either the North or South pole of the planet you're orbiting. What this does is anchor your target in orbit. While you and the target are in orbit, if you've correctly aligned your target, it will NEVER drift away from North/South. All you have to do to successfully dock is put your docking port/claw on the opposite pole of the target. Example (with docking ports):

Target Port Facing South (180 degrees)

{||||||}

....[]....

....[]....

{||||||}

Controlled Port Facing North (red line on navball)

Imagine grabbing that text illustration and holding it between your index and thumb in front of you. Now, "holding" that illustration, if you move your hands in a circle that goes from the screen to you (and not in a circle that goes from your head to your feet), you can see that while the illustration does indeed rotate around an invisible "planet" in front of you, the docking ports never move in relation. They're always facing North and South.

3) If you haven't done so yet, make sure you "target" the actual docking port you're intending to dock with and make sure you right click and choose "control from here" on the port that you intend to do the docking with. Then, when you're about 20m away from your target, just line up the yellow prograde marker (make sure your speed is in target mode!) with the purple target marker. What this means is that you are traveling straight towards the targeted docking port.

4) Once you're within 10m of target, ignore the navball. You will be too close for it to help you anymore and will find yourself drifting (even with the prograde marker on top of the target marker). Go from eye here on out and you'll be much better off.

5) Lastly, and it goes without saying, learn the RCS keys. To make docking even easier, after "controlling from here," press V until your camera is in "chase mode" and center it directly behind your craft. Try controlling it with RCS now. You'll find it waaaay easier to maneuver.

[giddonah]

Thanks everyone for your input and encouragement.

hahah, yeah, the claw was deployed

The two craft are both probes, so I'm not really losing anything by leaving them up there. I did get them rather close and stable, but my attachment failed. I'm thinking this has to do with my angle of approach and my speed being a little too high. I'll try the claw again some other time. For now, I'm going to take everyone's advice and just build a couple simple rockets with docks and rcs and just practice before making this part of some inter-planetary mission. I'm sure I'll get it eventually and it won't be such a big deal anymore (like landing on Mun was). Right now I want to get to the point where I can transfer fuel, so having an actual goal makes me want to stick with it.

Thanks again everyone!

[gazzareth]

I have been trying to use the claw the same way,in my case docking probes to a mothership which is probably 100x the weight of the probe. You can dock it with next to no velocity, just get it onto the claw and rcs onto it a couple of times. However, after I managed to do that my orbit went from 120k round to sub-orbital so not convinced I will be persisting with idea...

G

[Pecan]

...I'm sure I'll get it eventually and it won't be such a big deal anymore (like landing on Mun was). Right now I want to get to the point where I can transfer fuel, so having an actual goal makes me want to stick with it.

This is so much the right attitude, well done.

Small ships that are relatively easy to dock are the way to go and practicing with RCS and docking ports will pay off. Don't make it hard on yourself when you're starting; use the RCS, get the techniques nailed and, yes again, once you've got it you'll wonder why you ever found it so hard for so long.

And that's just one of the reasons KSP is so great - we choose to do these things ... not because they are easy but because they are hard.

[giddonah]

So I just wanted to report back. This was by far the hardest thing I've done in this game yet. It probably wasn't the prettiest docking maneuver, but I did manage to dock and transfer fuel. Used the Clamp-O-Tron and lots of RCS adjustments and zero mods. It was incredibly tedious, and I'm sure I'll waste less fuel the better I get at this. I'm just going to watch this thing orbit for a few minutes now.

Thanks!!

[DBT85]

Congratulations :-) it's always a good moment when you dock for the first time. I find it much easier with RCS as I have much more precise control over everything.

My only tip is to put something in orbit with a few docking ports on and make the smallest lightest ship you can to practise rendezvous and docking until you nail it every time.

It does get a lot easier once you've wrapped your brain around it.

[Random Tank]

It's funny how many times people need to say 'the claw needs some speed to attach properly' before they realise others have already said it... Do people not read previous posts or something? :/

One thing with the claw: Were you controlling the ship that had the claw? The claw won't work if it's mounted on an uncontrolled vessel which you're trying to dock to, it has to be on the controlled vessel...

[giddonah]

Ah, that's a great tip. The claw was on the ship I was using to "ram" with, so I think the problems were all with my speed/angle. I'll definitely remember for the future that you can't ram into a claw, that it's got to be on the ship you're controlling.