Docking training session; any tips?

[Rmack]

I've been trying to do the docking training scenario, but I just can't get it.

I can get the tilt down to zero, but trying to set up a burn that matches that orbit is eluding me.  I pull the prograde until my orbit gets up to the stranded ship, but I can barely get one set of the pink and gold markers to line up, let alone both at the same time.  I've tried playing with normal/antinormal, but still can't get all four of them lined up.  Going with one set matched doesn't seem to leave enough fuel to do anything left.

How do I get both sets of markers lined up?  I do have to get the same colors matching, right?  I've hit a couple spots where they merge and become one color, but that doesn't seem to be it.

Is there anyway of getting more fuel in a training exercise, so I can experiment more?

[James Kerman]

You can use the debug menu to enable unlimited fuel.  Alt + F12 by default.

[Reactordrone]

Once you've done the plane change you'll have to set up the manoeuvre node about a third of an orbit ahead of your position in order to get the right phase angle for an intercept. If you've done a few orbits and aren't in the start position you can just go around until you're approaching the right angle with respect to the target and then place a node just in front of you to set up the intercept.

Edited May 16, 2016 by Reactordrone

[Rmack]

Well, I finally intercepted.  I was within 100 meters, but I couldn't get closer.  The target ship seemed to be circling me.  I would thrust towards it, using main engine on low throttle, but after getting within a few dozen meters, the distance would start increasing again.  All the while changing relative position, as I said, so it seemed like it was circling me.

I thought that if I got within a hundred meters, I would be able to just translate over.  I was both below 10 m/s and faster sometimes, but to no avail.  Any idea what's going wrong?

Also, is there any way to save a training session, so I don't have to go through all of the preliminaries before trying the close approach?

1 hour ago, Reactordrone said:

Once you've done the plane change you'll have to set up the manoeuvre node about a third of an orbit ahead of your position in order to get the right phase angle for an intercept. If you've done a few orbits and aren't in the start position you can just go around until you're approaching the right angle with respect to the target and then place a node just in front of you to set up the intercept.

I wish I could see these screen shots, but I'm on a laptop, and the info is just too small.

What is the extra writing in yellow?  That doesn't happen in my training exercise.

Edited May 16, 2016 by Rmack

[Reactordrone]

8 minutes ago, Rmack said:

Well, I finally intercepted.  I was within 100 meters, but I couldn't get closer.  The target ship seemed to be circling me.  I would thrust towards it, using main engine on low throttle, but after getting within a few dozen meters, the distance would start increasing again.  All the while changing relative position, as I said, so it seemed like it was circling me.

I thought that if I got within a hundred meters, I would be able to just translate over.  I was both below 10 m/s and faster sometimes, but to no avail.  Any idea what's going wrong?

Also, is there any way to save a training session, so I don't have to go through all of the preliminaries before trying the close approach?

I wish I could see these screen shots, but I'm on a laptop, and the info is just too small.

What is the extra writing in yellow?  That doesn't happen in my training exercise.

Once you're within 100m kill all of your velocity relative to the target by burning retrograde in target mode. You can then point at target prograde and slowly thrust towards it with the RCS at less than 1m/s.You want the prograde and target prograde markers on top of each other. Use RCS translation controls to push the prograde marker around. If you aren't lined up on the other port select target prograde hold with the SAS and translate to move your ship in front of the other ship's docking port.

The extra writing is just a few notes I put on to help explain the process.

[Rmack]

7 minutes ago, Reactordrone said:

Once you're within 100m kill all of your velocity relative to the target by burning retrograde in target mode. You can then point at target prograde and slowly thrust towards it with the RCS at less than 1m/s.You want the prograde and target prograde markers on top of each other. Use RCS translation controls to push the prograde marker around. If you aren't lined up on the other port select target prograde hold with the SAS and translate to move your ship in front of the other ship's docking port.

The extra writing is just a few notes I put on to help explain the process.

OK, if I remember right (I'm still sort of punch-drunk from doing almost nothing except flying around in space for over eight hours) I did null the closing rate (delta-v, right) to 0.  I'm thinking I did this at under the 5k distance to target.  So, I messed things up moving in too fast?  I thought I only used time acceleration, but there were a lot of new things going on.

Didn't Gene say to stay under 10 m/s for the approach from 100 meters?  Now that I think about it, that does seem high.  Did I confuse this with the 1000m transition.  That would seem to make more sense.

So, I should stay on my approach vector till under 100m and then null my closure to 0?  I was fixated on my distance, and didn't worry about the closure rate, figuring I had plenty of time to null that out.

Thank you very much for helping a newbie.  I'll try this next time. If I'm right about this, that is.

Also, Gene was telling me to select the docking port on the target ship as my target.  I couldn't do this from my view screen.  Is there a way to make the target ship your view subject?

The in-game index isn't that good.  Can anyone recommend a good wiki or something to have open on my second computer?

[Rmack]

4 hours ago, Rmack said:

I've been trying to do the docking training scenario, but I just can't get it.

I can get the tilt down to zero, but trying to set up a burn that matches that orbit is eluding me.  I pull the prograde until my orbit gets up to the stranded ship, but I can barely get one set of the pink and gold markers to line up, let alone both at the same time.  I've tried playing with normal/antinormal, but still can't get all four of them lined up. 

This is wrong.  I was actually fiddling with radial in/radial out.  Right?  I used normal/antinormal to adjust my orbital plane discrepancy.

[James Kerman]

One small mod you might consider is Docking Port Alignment Indicator.

[G'th]

A handy tip is to treat it like landing on the Mun. If you can do that, you can rendezvous and dock. 

Presuming you're launching to rendezvous, launch below and in front of your target when its approaching approximately 5* (that number may be off, but visually you're looking for an 8th Pie slice. So imagine a quarter circle and cut it in half) off the launch pad (IE, in map view, you can measure a 5* angle between the launch pad and the target). While doing this, make sure the target is set (right click and target), then, as you coast to apoapsis set up your maneuver node.

From here, play with it until you get a good encounter. At this stage, its okay to have it anywhere under 10km, though if you can launch and then circularize into physics load distance (2.3km or lower), then even better.  Once you have that node set up, go ahead and keep coasting and then make your burn. Be sure to start with your normal/anti-normal (The purple markers) to make sure you're as close to your targets plane as possible before doing anything else. It will help get you your encounter markers. A good tip here is to zoom in on your projected orbit and compare it to your targets orbit when it comes to burning normal or anti-normal.

Something to keep in mind here is that may have to raise your orbit higher than your targets orbit in order to hit the encounter. If you do this in map mode, watch the markers as you play with the nodes. Once the orange marker shows up, you should see one stay static while the other moves around the orbit. This will help guide you towards an encounter.

Then, once thats done, put your craft on prograde and turn on your RCS. Go into map view, focus on Kerbin (so your screen stays static rather than following your craft) and hover your mouse over your encounter markers (non static screen makes it a pain to keep your mouse on these markers) so it lists your sep distance and relative speed. Then, using the IJKL/HN keys, maneuver your craft so that the sep distance becomes lower and lower until you get as close as you want to get. 0.1km is ideal, though I typically prefer 0.3km, as it gives me some room to slow down without damaging my target. At this point, you may hit a point where you simply can't get the distance to go lower no matter which key you hit. In this case, plop a maneuver node on the next asc/desc node, and play with the node until the distance comes down.

Now, once your sep distance is perfect, the issue becomes your relative speed. This also needs to be as low as possible, but is much easier to manage once you have a good encounter. Ideally, you want to wait until you hit your encounter and come into physics load range. At this point, you're basically landing on the Mun, except the Mun in this case is your target. So, treat your pro/retrograde markers like you would on the Mun, but treat your target as the center of your navball. (like on the Mun when you want your retrograde marker to be in the center of the blue horizon, indicating your coming straight down).

Point your craft towards your anti-target marker (the Y shape one) and maneuver your retrograde marker onto it. If your relative speed is very high (2-300m/s range), you will want to use your actual engines for it, as RCS won't do it fast enough unless yours are very powerful (as in, beyond stock powerful) or you have a ton of them. Push the retro marker on to the anti-target, and then just keep it there as you slow down. The retro marker will move around during this.

Finally, once you've slowed down to about 10m/s or better, point your craft towards the target marker (the broken circle with a dot) and maneuver the prograde marker onto it. You will have to speed up a bit to do this, as your craft is still going backwards relative to the target. Then, just use your RCS to keep your prograde on the marker until you meet up with your target. Be sure during this to stay below 10m/s until you get comfortable doing it faster.

 

Docking isn't very hard once you've rendezvous'd. First set the port you want to dock to as your target, and align your craft with it. You don't want to rely on the target markers here, and instead eye ball it. You want your craft to be oriented in such a way that, if the port was directly in front of your craft, you could just RCS forward and dock. Once you're oriented and you have your relative speed cut down to a minimum, start using your RCS to maneuver to the port. Here, you definitely want to be patient, and keep CapsLock turned on at all times.

What this does is cut your input by a significant degree so that your RCS comes out in tiny, weak bursts rather than full power blasts. One or two pulses of your thrusters in the direction you need to move in is all you need at this stage. So, for example, lets say you've done all the above and your target port is 300m ahead of your craft, and to your crafts left and above it. So, 2 pulses to the left, 2 pulses forward, 2 pulses up. (in this case, the pulses would push to the right, backwards, and downward, respectively*) and wait. Once you start to get close, pulse in the opposite directions to slow down and eventually stop. At this point, you can pull up your nav ball, and presumably your target marker and prograde marker should be starting to get lined up, if they haven't already. If they have (that is, center of prograde on center of target), just pulse forward until you meet up and dock. If not, use your thrusters to get the markers lined up, and pulse forward. 

Once the ports meet, they should magnetize and then dock. If the ports are placed strangely (Such as part clipped, or if theres other things your craft may otherwise be colliding with, you may have to put some thrust forward in order to dock. 

[SalehRam]

Did not read the other replies, but I am sure they are well explained and detailed, but my short and quick tips are:

1. When you get really close to your target in orbit (such as 10km or around that range), your navball references will change to be related to your target velocity. If you are very close to your target, and your navball is still using your own orbit velocity as a reference, you can click the little box on top of the navball that shows what reference is the navball using (such as orbit, surface, or target).
2. Once your navball is referring to your target, first make sure you burn retrograde (related to the target) until you get your speed to be 0m/s related to the target speed.
3. Then point your craft to the target itself (the purple indicator on the navball), burn a little bit, this should set your prograde (relative to target) indicator on top of the target indicator.
4. Make sure you don't go fast, for starters do it slow, like 10m/s or something, then keep watching your prograde indicator, it WILL drift, watch it as it drifts away form the target indicator.
5. When you feel the drift is now large, you need to kill your relative velocity to the target, this will take you back to step 2, so go back to step 2 and repeat the circle until you get to meet your target.

Hope these helps, this is how I did it once I wanted to learn rendezvous and docking. Once you master this, you can make your rendezvous faster with more practice and time...

There is the mod Docking Port Alignment Indicator, which is an awesome docking mod, but I really don't recommend using mods for a thing until you know how it works without the mod, then use the mod to save time or have more controls or numbers at your screen. I only use this mod for large crafts dockings, but form medium/small ships, I just use the stock docking methods.

Edited May 16, 2016 by SalehRam

[bewing]

4 hours ago, Rmack said:

Well, I finally intercepted.  I was within 100 meters, but I couldn't get closer.  The target ship seemed to be circling me.  I would thrust towards it, using main engine on low throttle, but after getting within a few dozen meters, the distance would start increasing again.  All the while changing relative position, as I said, so it seemed like it was circling me.

I thought that if I got within a hundred meters, I would be able to just translate over.  I was both below 10 m/s and faster sometimes, but to no avail.  Any idea what's going wrong?

 

Heh. That's exactly what happened to me the first time I tried to intercept.  And that's exactly what I thought at the time, too.

But yes, the basic point is that you were going too fast. When you are down to 100m, it's probably a good idea to keep your speed down to .4 m/s or less until you get the hang of it. Also, if you miss, stop your ship! Then retry. Don't just turn and thrust again, or you will end up going faster and faster in circles around your target again.

The other part of the point is that there are things called "coriolis forces" when you pilot a ship in orbit. This is probably the main thing that the game is trying to teach you. When you thrust forward, the coriolis forces will always push you a little to the side. Until you are really close, you cannot just point your ship straight at a target and thrust -- or you will certainly miss. As you come in, even from 100 meters, you will need to adjust, and readjust.

 

[Rmack]

I've been trying to follow all the advice, and listen to Gene also.  I've got the game paused, I'm about 1000k away, closing 3.5 m/s.  I try everything I can think of, but it gets within a certain range, and starts widening again.

[SalehRam]

1000km is still very far away... usually rendezvous is considered possible when you get really really close like less than 50km or something...

You need to play with maneuver nodes to get much more close encounter...

Get yourself either in a higher orbit or lower orbit relative to your target and then place a meneuver node and play with it... dont worry if you need to complete multiple orbits before getting the close encounter you need... try to get something like 10km or less separation distance, then the tips we said above will help you reach your target...

Also make sure your ascend/descend nodes are no more than 1 or -1 degrees this is important

Edited May 16, 2016 by SalehRam

[Rmack]

Well, I finally hit my target vehicle.  And I do mean hit. Kaboom!

I'm on the road to success, though.   I learned the trick of thrusting on the other side of the target marker from the prograde marker to bring them together.  Being able to stop that waltzing around the target was a big win for me.  And a wiki mentioned that locked view now does what chase view used to, as the instructions in the tutorial said.

Question;  how far away from the target does the pulling the prograde marker to the target marker work?  I'm sure it's limited, but about how far?

 

Thanks again for all the help.  I'm go for another try!

[Reactordrone]

45 minutes ago, Rmack said:

Question;  how far away from the target does the pulling the prograde marker to the target marker work?  I'm sure it's limited, but about how far?

 

I'd say no further than about 10-15km from the target in most cases. Any further away and you may be correcting in the wrong direction since the marker positions will move around relative to each other as you orbit.

[Rmack]

45 minutes ago, Reactordrone said:

I'd say no further than about 10-15km from the target in most cases. Any further away and you may be correcting in the wrong direction since the marker positions will move around relative to each other as you orbit.

That's what I suspected, I just didn't have any experience on how far away that was.  It probably varies, too, depending on the planet, huh?

[SalehRam]

5 hours ago, Rmack said:

It probably varies, too, depending on the planet, huh?

Nah, it is not related to the planet, the body you are orbiting can only influence the orbital speed and altitude, but cannot affect the good separation distance which you can work in it to rendezvous...

At the end, when you are chasing/meeting an object in orbit, you don't really care about anything other than your relative velocity, inclination and distance from that object, other things (assuming you don't over correct and fall into atmosphere/surface) are just data (aka: have no meaning for you yet at this stage) for this situation.

[Plusck]

6 hours ago, Rmack said:

That's what I suspected, I just didn't have any experience on how far away that was.  It probably varies, too, depending on the planet, huh?

Sort of. It depends mostly on how tight the orbit is (which can be very tight around a small body), how eccentric it is and so on.

Generally speaking, once I have a close rendezvous to my target in map view, I warp ahead to about 1/8th of an orbit before the encounter to push retrograde over antitarget a little, then warp again about 1/16th of an orbit further to do the same thing again. In most cases this improves the final encounter. In some cases, however, this can slow you down too much: from only just touching, your orbit and the target orbit will start to separate, so you have to flip around and burn towards the target instead (and in this case, burning has the effect of "pulling" prograde towards where you burn).

If your orbit is very eccentric, and you are trying to meet near the periapsis, you might find that even a relatively short distance away from the target, heading straight for the target sets you on a trajectory which will miss it. In this case you really have no option but to use a maneuvre node to find the right collision course.

edit: ah - I misread you. You were saying how far away does pulling prograde over target work. Yes, this only works much closer than pushing retrograde over antitarget, since by increasing your velocity to target you are increasing the difference between your two orbits.

Edited May 17, 2016 by Plusck

[Rmack]

I finally did it!  I docked.

THAT WAS NOT EASY!!

Thanks for all the tips, everybody.  What should I try next?

 

Uh, how do I get control of my ship again after transferring crew?

 

Edited May 17, 2016 by Rmack

[SalehRam]

2 hours ago, Rmack said:

I finally did it!  I docked.

THAT WAS NOT EASY!!

Thanks for all the tips, everybody.  What should I try next?

 

Uh, how do I get control of my ship again after transferring crew?

 

I would say go hunt for asteroids... They are more PITA to rendezvous with than normal ships specially if they have a trajectory inside Kerbin SOI...

Or maybe mess with aerobraking and atmospheric reentry, that will become very useful later in the advanced stages of your game...

Maybe also build a modular space station now that you can dock stuff together, you can build an all purpose interplanetary ship that can go anywhere...

For getting control back of your ship, maybe try the keys "[" or "]" switch to something other than your ship, then switch back to it, that should fix things if you cannot control it somehow. IF you are using REMOTETECH, then that is a different story, where you need an active antenna and an active connection to KSC or a command station to be able to control probes and unmanned ships...

Edited May 17, 2016 by SalehRam

[Reactordrone]

4 hours ago, Rmack said:

I finally did it!  I docked.

THAT WAS NOT EASY!!

Thanks for all the tips, everybody.  What should I try next?

 

Uh, how do I get control of my ship again after transferring crew?

 

You could try a space station or space debris clean up with the klaw. Docking is one of the harder parts of the game to learn and practice will make it much easier.

 

To undock and return the crew in the training mission right click on one of the docking ports and select undock. Only one of the ports will have that option so you may need to try both, (also if you're undocking a part that's never been docked before it will say decouple node rather than undock.)

[Rmack]

5 hours ago, Rmack said:

I finally did it!  I docked.

THAT WAS NOT EASY!!

Thanks for all the tips, everybody.  What should I try next?

 

Uh, how do I get control of my ship again after transferring crew?

 

I'm an adrenaline-addled fool.  I probably need to do this a few more times at least.  Not to mention the landing tutorials.