rendezvous and docking - separating the men from the boys

[GungaDin]

This seems to be the big hurdle in space travel and I have not managed it yet.  If someone can recommend a good document or video I would appreciate it. I've seen Scott Manlys and some others but they are frustrating to watch and sometimes run right past where the detail is that you need.  

I can navigate close to my target, like within 10 clicks, but after that I panic and go all wonky. 

I would PAY for a pause button with this sim like EVERY OTHER sim I've ever played or heard of!!! Has anyone ever learned why KSP does not have that feature?  In my glorious sim career I have torpedoed the Yamato and lander a Viper with the HUD blown out but I would never have learned what was going in without being able to pause and see things from different angles.  Anyway.  End of Rant...

Anyway when I'm under 10K and closing on my target I get disoriented.  It's not just the whacky Newtonian physics when in orbit but the disorientation of direction and the poor camera controls.

Any help in the way of references would be appreciated.   I refuse to give up.

 

[bewing]

37 minutes ago, GungaDin said:

but the disorientation of direction and the poor camera controls

You do not need to use the camera or any direction info to rendezvous. The difficulty of a rendezvous depends on your orbital velocity. To rendezvous, you exclusively use map mode and the navball until you are within a few hundred meters of your target. 10km is the very outer limit for beginning an actual rendezvous maneuver for an expert at doing rendezvous. A rendezvous beginner needs to use orbital maneuvers in map mode to get within 1km before even thinking about the final rendezvous.

Once you are within 10km, look at your orbit relative to your target. Correct the inclination error at the An/Dn. Your orbit needs to cross your target's orbit. If your target is behind you, you need to slow down -- so raise your Ap until the "closest approach" goes below 500m. Otherwise, lower your Pe until your closest approach goes below 500m. Once you get to your closest approach, burn retrograde in target mode until your relative velocity goes to 0.0 m/s. Now you are stopped relative to your target. Point your nose at your target, give your craft a little gas, and when you get below 30m separation burn retrograde in target mode until you are at 0.0 m/s again. You have now accomplished a rendezvous.

Now point directly at your docking port, give your craft a little thrust (up to maybe 0.5 m/s), and complete your docking.

An advanced technique for rendezvous is to "push or pull your retrograde/prograde marker around on your navball" as you approach your target. But I'd recommend doing it the easy way (above) first.

Edited November 9, 2019 by bewing

[Superfluous J]

16 minutes ago, GungaDin said:

This seems to be the big hurdle in space travel and I have not managed it yet.  If someone can recommend a good document or video I would appreciate it. I've seen Scott Manlys and some others but they are frustrating to watch and sometimes run right past where the detail is that you need.

 I'm pretty proud of my rendezvous and docking tutorial videos, in 3 handy spoilers below, rendezvous, approach, and docking.

Spoiler

 

Spoiler

 

Spoiler

 

16 minutes ago, GungaDin said:

I would PAY for a pause button with this sim like EVERY OTHER sim I've ever played or heard of!!! Has anyone ever learned why KSP does not have that feature?  In my glorious sim career I have torpedoed the Yamato and lander a Viper with the HUD blown out but I would never have learned what was going in without being able to pause and see things from different angles.  Anyway.  End of Rant...

I don't have any inside knowledge or anything but I always figured you can't pause because NASA can't pause.

16 minutes ago, GungaDin said:

Anyway when I'm under 10K and closing on my target I get disoriented.  It's not just the whacky Newtonian physics when in orbit but the disorientation of direction and the poor camera controls.

For sure you need part 1 above. And maybe part 2.

16 minutes ago, GungaDin said:

Any help in the way of references would be appreciated.   I refuse to give up

Good!

[Waxing_Kibbous]

lots of good tutorials but this one clicked for me when I first started. Start with some LKO rescues first and park closer and closer until you get comfortable with rendevous, then try docking. First time docking line everything up so that the ports are facing each other and the vessels are on parallel lines, then just rcs slowly. I find orienting the craft you control so that the rcs controls are really on axis, aka don't mess with diagonal rcs movements or inverted movements, is important. Trust me, once you have a couple under your belt it becomes second nature and pretty relaxing to do.

https://www.youtube.com/watch?v=1v1ZLXLBMQo

 

[Goody1981]

Bewing’s response is excellent (as are, I’m sure, 5thhorseman’s videos even though I didn’t watch them).. but to summarise in fewer words:

1 - get an intercept as close as possible. 10km is pretty far, as Bewing says aim for 1km

2 - at 1min before intercept, quicksave

3 - burn retrograde in target mode (do you know how to change modes?) until your speed is 0.

4 - burn prograde in target mode until speed is 10m/s and wait until the distance to target reduces by half

5 - repeat steps 3 and 4 until you are stopped next to your target

Then it’s time to dock (I’m assuming your difficulty is getting close enough to attempt docking, not the docking itself)

Edited November 9, 2019 by Goody1981

[Foxster]

I personally find docking tiresome. It's not like anyone in real life would do it without computer aid these days. So if you too find it tedious then I recommend MechJeb's docking tool. 

Edited November 9, 2019 by Foxster

[AHHans]

My $0.05: for a rendezvous in low [Kerbin/Duna/Eve/whatever] orbit, I fiddle with the maneuver nodes until the predicted closest approach is way closer than 10 km. I usually go to at least less than 1 km, with 0.3 km being a typical value. Then while performing that maneuver I keep an eye on the closest approach in the approach info tab in the maneuver display (that was introduced with KSP 1.7), to see how close I can get. Then, during the approach, I follow the method outlined in @Snark's Illustrated guide to docking to refine my trajectory and get close to the target.

 

[DunaManiac]

What I do is that I move in my closest approach in to as close as possible, even right on top of it! The way that you do this is that if you are within 10km (as said in the OP), you not only have to just point at the target and burn, you also need to move the prograde vector so that it is aligned with the target in the target mode on the nav-ball. Slow to stop near the spacecraft, then right click on the target where you want to dock at, it will set your target to where the target docking port is. Then, use your RCS thrusters to maneuver in, (the controls are IJKLHN, not WASD). If you get close enough to the docking port, the ports will attract together, pulling your two ships together.

[Vanamonde]

I made a trainer that launches as one and then can undock two smaller ships so that people can practice just the last phase of docking without having to fly a rendezvous first. May be useful? 

[GungaDin]

Sure but how does the craft fly itself??

[GungaDin]

Thanks to all of you.  Great stuff - I'm off to try it but here a few follow up questions... 

1 - When in target mode the Nav Ball shows relative speed but does not indicate if I am closing or parting.  Am I missing something or do you have to  determine that on the fly by seeing if the distance is changing?

2 - You all seem to be able to get your intercept points to within a few K but my problem is that the slightest twitch of my hand moves them by quite a lot. Again am I doing it wrong is is this just a matter practice?

[Zeiss Ikon]

The Nav ball has different symbols for prograde ( closing with target) and retrograde ( moving away from target).  If your prograde marker is on or close to the target marker on the nav ball, you're approaching.  If it's the retrograde marker near the target, you're moving away.

When you click the handles on the maneuver node, you can hold the shift key (IIRC -- been playing RO so long and so badly, I haven't done a rendezvous in a year or more -- just today got an RO career to the point of using nodes again) to greatly slow the rate of change for a given movement of the node handle.

[Goody1981]

8 hours ago, GungaDin said:

2 - You all seem to be able to get your intercept points to within a few K but my problem is that the slightest twitch of my hand moves them by quite a lot. Again am I doing it wrong is is this just a matter practice?

Also are you aware of being able to use the mouse wheel to make slight adjustments?

[AHHans]

9 hours ago, GungaDin said:

1 - When in target mode the Nav Ball shows relative speed but does not indicate if I am closing or parting.  Am I missing something or do you have to  determine that on the fly by seeing if the distance is changing?

You are not really missing anything. But when I switch from map view to vessel view a few minutes before the (predicted) intercept, then I kind of assume that I'm closing. Also when I set my vessel to point target-retrograde and I see that it is pointing its ass - errr ... the end with the rocket engines - towards the target then I also know I'm closing. And finally if I see target-retrograde marker on the navball next to the "retro-target" marker (this one: ) - or prograde next to target - then I'm also closing.

9 hours ago, GungaDin said:

2 - You all seem to be able to get your intercept points to within a few K but my problem is that the slightest twitch of my hand moves them by quite a lot. Again am I doing it wrong is is this just a matter practice?

Are you talking about setting up the maneuver node, or actually doing the burn? For the first one see @Goody1981 comment: I use the mouse wheel (one "click" at a time) for fin adjustments. For the second: it's a combination of practice and reducing the engine thrust. Sometimes I also do some corrections with small puffs of RCS.

[GungaDin]

On 11/9/2019 at 9:48 PM, Zeiss Ikon said:

The Nav ball has different symbols for prograde ( closing with target) and retrograde ( moving away from target).  If your prograde marker is on or close to the target marker on the nav ball, you're approaching.  If it's the retrograde marker near the target, you're moving away.

When you click the handles on the maneuver node, you can hold the shift key (IIRC -- been playing RO so long and so badly, I haven't done a rendezvous in a year or more -- just today got an RO career to the point of using nodes again) to greatly slow the rate of change for a given movement of the node handle.

Interesting. I tried holding the shift key but that's the throttle!  I'll try the mouse wheel tonight.  I'm making progress though!  Got within 200 M last night and then - guess what! I ran out of electricity and could only maneuver with engines thrusting.  I'll slap on some solar panels and try again tonight.

Edited November 11, 2019 by GungaDin

[Dan Kerman]

Best tutorial I have seen...  taught me how and now it's pretty easy.. 

 

Illustrated Guide to Docking

[Zeiss Ikon]

7 hours ago, GungaDin said:

Interesting. I tried holding the shift key but that's the throttle!

Other shift?  I'm on Linux; my two shift keys have different functions in game.  If you're on Windows, it may be ALT instead.

[MPDerksen]

I would only consider myself an Intermediate player.  Nothing like some of the pros here.  But I do seem to have no issues docking anymore, and have a few additional tips:

1.  I don't use RCS at all.  I don't even put them on the ship.  Get close, burn retrograde to the target (making sure the navball is in that mode) until I hit 0.0.  Then flip around, and burn at the target (pink circle) slightly and the prograde marker will appear on top of the target marker.  Repeat with smaller and smaller changes in velocity.
2.  Once you are within 2km, you can switch back and forth between the 2 vessels.  You want to make sure the target points it's docking port at the incoming vessel.  Right click on the incoming docking port and select as target.  Then, back to the other, and re align that one.  Back and forth.  SLOWLY.  this is why approaching at just a few meters/second is wise.
3.  Right click on the engine of the craft you are flying towards the target, and lower the thrust from 100 down to as little as you need (5?).  Then, when you thrust forward, you don't go zooming along.  However, you still need enough that you can kill your relative velocity when you go retrograde.  I tend to use around 20%.  Hitting "Z" still gives me a nice push, but a single "Shift" is a very gentle nudge.
4.  If you have it unlocked, try using the advanced grabber unit.  You can "stick" it onto the side of a target's fuel tank, and has a wider cone to connect.
5.  Similar to #3 above, I tend to get my encounter arrows close, but then not use a maneuver node to fine tune at all.  I turn my thrust way down, and make small thrusts while watching the distance in Map view.  I'll watch it close, for example, from 10km down to 2km, then start to rise again, and I hit "X" and stop.  Once you do get close, if your relative velocity is pretty high, you will want your engine back at 100% to get to 0.0m/s as quickly as possible (this happens when you cross paths, but your orbits are vastly different.

I suddenly was able to do this when I realized I needed to stop looking at my orbit once I got the target in view and ONLY look at the navball in Target mode to adjust from there.

[MPDerksen]

Oh yeah, last thing:  you ask how you know if you are getting closer to, or further from, your target?  If the NavBall is in Target mode, the Retrograde marker REDUCES THE RELATIVE SPEED BETWEEN THEM.  If you were flying towards your target, Retrograde would slow your approach.  If you are flying away from your target, Retrograde will slow your path away from it.  In other words, it won't matter.  Your NavBall will read your relative velocity in m/s.  This number goes down when you burn Retrograde.  Once the rate <1.0, the marker disappears and you are left with just SAS.  then you have to find the pink circle to point your ship at/from your target.  

Is that helpful? 

[Snark]

On 11/11/2019 at 12:43 PM, Dan Kerman said:

Best tutorial I have seen...  taught me how and now it's pretty easy..

Illustrated Guide to Docking

Thanks. 

I got tired of forever having to link people to an archived page, and couldn't stand it any longer, so I just now went and ported it to the Tutorials subforum here:

Hopefully that'll make it a bit easier for folks to find.