Docking with Richfal - Orbital Rendezvous II

[MajorMushroom]

Some may remember my first topic of Saving Richfal, where I asked about the basics of an orbital rendezvous. Now that’s all we’ll and good, I can get a lovely intercept and that’s all solved. But now, docking. However this time the question is simple and only really requires one answer: Is there a way to align docking ports, for an easier time? The only way I can thing of is to be able to use SAS to lock onto target, but say I’m using a drone, is there another way? Because my main problem is that I keep missing ports. How can this be fixed?

[Cpt Kerbalkrunch]

As long as you still have power in the vehicle you're going to rescue, it's pretty easy to line them up. Once you have a close enough rendezvous and kill relative velocity, target the stranded ship and the hit "target hold" on your SAS. Now switch to the stranded vessel and target your rescue ship. Hit "target hold" again. Now both ships' docking ports are lined up and the two ships are "not moving". Switch back to the rescue ship and start easing forward with your RCS. Have SAS on "hold" only. Not "target hold". The reason why is that you'll most likely need to maneuver a bit to stay lined up. Move forward really slow; like .2-.4 m/s. Use timewarp to speed things up, and kill it if you start drifting. Just keep your prograde marker lined up with the target marker and you should be fine. And you can always hit "n", kill all relative velocity, line up the ports again, and then start moving forward again. It's not a race. Until you get used to it, just go slowly. You'll get it.

And you're probably already familiar with it, but I neglected to mention that you should right-click each ship's docking port and hit "control from here", and when you're within 150m or so, right-click each of the other ships' docking ports and hit "set as target". If they're small ships, it won't make a huge difference, but the extra precision certainly won't hurt.

Edited October 14, 2017 by Cpt Kerbalkrunch

[MajorMushroom]

14 minutes ago, Cpt Kerbalkrunch said:

As long as you still have power in the vehicle you're going to rescue, it's pretty easy to line them up. Once you have a close enough rendezvous and kill relative velocity, target the stranded ship and the hit "target hold" on your SAS. Now switch to the stranded vessel and target your rescue ship. Hit "target hold" again. Now both ships' docking ports are lined up and the two ships are "not moving". Switch back to the rescue ship and start easing forward with your RCS. Have SAS on "hold" only. Not "target hold". The reason why is that you'll most likely need to maneuver a bit to stay lined up. Move forward really slow; like .2-.4 m/s. Use timewarp to speed things up, and kill it if you start drifting. Just keep your prograde marker lined up with the target marker and you should be fine. And you can always hit "n", kill all relative velocity, line up the ports again, and then start moving forward again. It's not a race. Until you get used to it, just go slowly. You'll get it.

And you're probably already familiar with it, but I neglected to mention that you should right-click each ship's docking port and hit "control from here", and when you're within 150m or so, right-click each of the other ships' docking ports and hit "set as target". If they're small ships, it won't make a huge difference, but the extra precision certainly won't hurt.

Ah, that was a bit of an issue as I was using a basic probe core with no SAS options. I’ll be using pilots more often so it shouldn’t be much of an issue. Thank you for the advice

[Cpt Kerbalkrunch]

19 minutes ago, MajorMushroom said:

Ah, that was a bit of an issue as I was using a basic probe core with no SAS options. I’ll be using pilots more often so it shouldn’t be much of an issue. Thank you for the advice

You won't have the "hold" options then, but you'll still be able to see the markers themselves. You'll just have to turn the ship until you line up the markers. As long as you at least have the ability to see the markers and control both ships, you'll still be okay. Until you get used to it, I think moving slowly is the key. Just use timewarp to speed things up so you don't lose your mind. But it's a lot easier to slow time than your ship.

But for future docking, you'll want better probe cores/command modules, not just for the better SAS controls, but also for their reaction wheels. You want to have responsive controls when making the fine adjustments that are often necessary for docking. RCS can help provide control, but also propulsion; so that as it's turning your ship, it's also pushing your ship (however minutely) in one direction or another.

Edited October 14, 2017 by Cpt Kerbalkrunch

[Spricigo]

25 minutes ago, Cpt Kerbalkrunch said:

RCS can help provide control, but also propulsion; so that as it's turning your ship, it's also pushing your ship (however minutely) in one direction or another.

My advice: don't use RCS for orientation, let reaction wheels deal with this. Have your RCS thrusters set to only respond to translation commands. (Needs advanced twekables enabled in settings,  on context window click show activation toggles)

The advantage are: 1.No monopropelant used to steer the vessel.  2. Rotation commands don't cause  unsolicited translation. 

 

 

[Cpt Kerbalkrunch]

2 minutes ago, Spricigo said:

My advice: don't use RCS for orientation, let reaction wheels deal with this. Have your RCS thrusters set to only respond to translation commands. (Needs advanced twekables enabled in settings,  on context window click show activation toggles)

The advantage are: 1.No monopropelant used to steer the vessel.  2. Rotation commands don't cause  unsolicited translation. 

 

 

That's what I was advising. The OP has a basic probe core without SAS options. I'm assuming that means it doesn't have reaction wheels either. I was explaining that RCS can be used for alignment, but reaction wheels are better for the task because they aren't pushing you off course at the same time as they're trying to line you up. For me, the weight is not a concern. Just results and ease of use.

[Quoniam Kerman]

In career mode, inexperienced pilots can't hold on target, no? I'm having a lot of issues to dock two early ships together with only some RCS on the front (M.O.L.E mod capsules), I just can't get the ships aligned with eachother and keep circling around one another, it is quite annoying, been doing that for two hours.

In fact I HATE docking, that's why I don't make space stations or refueling ships to begin with... Why I don't do Apollo style missions either. I wish developers or modders would make a functionality to make ships dock automatically, really.

A simple orbital rendez-vous without docking is fine, transfer crew via EVA is alright. But docking, pls no.

Edited October 15, 2017 by Quoniam Kerman

[Cpt Kerbalkrunch]

34 minutes ago, Quoniam Kerman said:

In career mode, inexperienced pilots can't hold on target, no? I'm having a lot of issues to dock two early ships together with only some RCS on the front (M.O.L.E mod capsules), I just can't get the ships aligned with eachother and keep circling around one another, it is quite annoying, been doing that for two hours.

In fact I HATE docking, that's why I don't make space stations or refueling ships to begin with... Why I don't do Apollo style missions either. I wish developers or modders would make a functionality to make ships dock automatically, really.

A simple orbital rendez-vous without docking is fine, transfer crew via EVA is alright. But docking, pls no.

Docking is one of the toughest things to do in this game; until you get used to it. Then you'll wonder why you had such a hard time with it in the first place. It's all about relative velocity. You already know to set your navball to "target" mode. Once you do, and you near your rendezvous with the other ship, burn retrograde until the navball reads zero. At that point...

8 hours ago, Cpt Kerbalkrunch said:

Once you have a close enough rendezvous and kill relative velocity, target the stranded ship and the hit "target hold" on your SAS. Now switch to the stranded vessel and target your rescue ship. Hit "target hold" again. Now both ships' docking ports are lined up and the two ships are "not moving". Switch back to the rescue ship and start easing forward with your RCS. Have SAS on "hold" only. Not "target hold". The reason why is that you'll most likely need to maneuver a bit to stay lined up. Move forward really slow; like .2-.4 m/s. Use timewarp to speed things up, and kill it if you start drifting. Just keep your prograde marker lined up with the target marker and you should be fine. And you can always hit "n", kill all relative velocity, line up the ports again, and then start moving forward again. It's not a race. Until you get used to it, just go slowly. You'll get it.

And you're probably already familiar with it, but I neglected to mention that you should right-click each ship's docking port and hit "control from here", and when you're within 150m or so, right-click each of the other ships' docking ports and hit "set as target". If they're small ships, it won't make a huge difference, but the extra precision certainly won't hurt.

 

7 hours ago, Cpt Kerbalkrunch said:

You won't have the "hold" options then, but you'll still be able to see the markers themselves. You'll just have to turn the ship until you line up the markers. As long as you at least have the ability to see the markers and control both ships, you'll still be okay. Until you get used to it, I think moving slowly is the key. Just use timewarp to speed things up so you don't lose your mind. But it's a lot easier to slow time than your ship.

But for future docking, you'll want better probe cores/command modules, not just for the better SAS controls, but also for their reaction wheels. You want to have responsive controls when making the fine adjustments that are often necessary for docking. RCS can help provide control, but also propulsion; so that as it's turning your ship, it's also pushing your ship (however minutely) in one direction or another.

Just move slowly, and don't give up. You will learn to dock. And when you do, it'll open up a whole new world. There'll be nothing you can't do, and all the other things will follow.

[Geonovast]

6 minutes ago, Cpt Kerbalkrunch said:

Docking is one of the toughest things to do in this game; until you get used to it. Then you'll wonder why you had such a hard time with it in the first place. It's all about relative velocity. You already know to set your navball to "target" mode. Once you do, and you near your rendezvous with the other ship, burn retrograde until the navball reads zero. At that point...

I thought it was incredibly frustrating until I learned how to line up the prograde marker with the target marker on the navball.  Now I'll typically have to make almost no adjustments while drifting in for the last couple hundred meters.  Usually none if I'm in high orbit.  I love docking now.

The Navball by itself can be very intimidating until you get used to it. 

[Quoniam Kerman]

I still don't get to do it properly. I still have the ship overlap eachother no matter what I do. I tried the tutorial scenarios, I couln't get to complete them, spent hours to try to aign two ships sith each other, no way, i can't achieve it.

I try to be at 0.1 m/s relatiive velocity, even with that I can't adjust. when I burn to be at 0 m/s I can't adjust, each maneuver makes it worse. I can't get those markers aligned properly each time I try to burn to akigne them, they seem to go apart even more. Maybe it is because the ship turn too slowly, I seem to be able to do it with a Kerbal on EVA because its RCS react much faster.

It might be because I don't align the markers in the right order (direction, target attitude, I seem to be doing do the opposite each time)

Edited October 15, 2017 by Quoniam Kerman

[Geonovast]

10 minutes ago, Quoniam Kerman said:

I still don't get to do it properly. I still have the ship overlap eachother no matter what I do. I tried the tutorial scenarios, I couln't get to complete them, spent hours to try to aign two ships sith each other, no way, i can't achieve it.

I try to be at 0.1 m/s relatiive velocity, even with that I can't adjust. when I burn to be at 0 m/s I can't adjust, each maneuver makes it worse. I can't get those markers aligned properly each time I try to burn to akigne them, they seem to go apart even more. Maybe it is because the ship turn too slowly, I seem to be able to do it with a Kerbal on EVA because its RCS react much faster.

Are you doing it with full SAS capabilities (like in sandbox or an advanced career)?

The built-in docking tutorial is... not great.  I was never able to complete it either, and I pretty much ended up orbiting the ship I was trying to dock with.

[Quoniam Kerman]

No in carreer mode, both my pilots only are at lvl1, they only can hold prograde and retrograde, and can't hold the other direction nor can they hold target. I'm only on normal difficulty, btw. And as you I can only turn around the ship I want to dock, even if I switch ships to make them face eachother. I'm orbiting Kerbin at approx 120 km. At first I thought I was doing docking maneuvers too low so orbuits were too fast, but I tried in sandbox around Minmus, even around a low gravity bory I can't do it with fully equipped ships and fully trained pilots, so I guess it is really a method problem. There is something I don't do right at some point, maybe I try to aign too close from the target (below 100 m) The ship maneuvers too slowly, it puts my nerves on fire and I lose it. Controls are never aligned so I always get to try to see in what direction goes what key, very frustrating. I'm amazed at yyoutubers getting docking at firs t sight as though they get to love their girl at first date... Unicums...

Edited October 15, 2017 by Quoniam Kerman

[Geonovast]

3 minutes ago, Quoniam Kerman said:

No in carreer mode, both my pilots only are at lvl1, they only can hold prograde and retrograde, and can't hold the other direction nor can they hold target. I'm only on normal difficulty, btw. And as you I can only turn around the ship I want to dock, even if I switch ships to make them face eachother.

That's probably why it's so hard.  I wouldn't worry about docking too much until your pilots are more experienced and can hold target.

Also not a bad idea to practice some in a sandbox save just to get the hang of it.

[Quoniam Kerman]

I tell you, even in sandbox, I can't do it...

[Spricigo]

Maybe a videotutorial may help you visualize (pun attempted)

 

[MajorMushroom]

4 hours ago, Quoniam Kerman said:

I tell you, even in sandbox, I can't do it...

I know I’m no expert, but something I learned as well was to use IJKL like WASD to control RCS better. You can use this to try and align prograde and target markers. I think..

[Quoniam Kerman]

Thx for the tutorial, but it didn't teach me anything new.  I tried in Sandbox with the same ships, for once the ships are nicely paralel but can't adjust themselves to be exactly in front of eachother. This is so frustrating ! Even with cheated perfects orbits I can't do it ! LOL even cheats can't make me do it ! Also, it doesn't help, I always seem to encounter my target at nitght time... But since I spend hours circling around it I also have daytime, but even in daytime, I'm clueless...

Edited October 15, 2017 by Quoniam Kerman

[MajorMushroom]

5 hours ago, Quoniam Kerman said:

Thx for the tutorial, but it didn't teach me anything new.  I tried in Sandbox with the same ships, for once the ships are nicely paralel but can't adjust themselves to be exactly in front of eachother. This is so frustrating ! Even with cheated perfects orbits I can't do it ! LOL even cheats can't make me do it ! Also, it doesn't help, I always seem to encounter my target at nitght time... But since I spend hours circling around it I also have daytime, but even in daytime, I'm clueless...

If you could set up a recording system to record your screen, I’m sure that could help others help you. Or perhaps take a few f1 screenshots and describe what your doing, so that some experts can help you directly. 

Also about the night time issue, try to fit some lights if you can, and align your ships with that light glow of the universe that spans across horizontaly.

As a rookie myself I know how frustrating it is when the only advice left is ‘just practice’ but I’m thinking that’s all you can do. Maybe try a ‘I’ll try this’ approach where you try different things and see what happens, it might just help  

[Geonovast]

To combat the nighttime issue, you can also crank up the ambient light boost, at least temporarily.  Basically negates the problems with it being night.

[Grand Ship Builder]

Right click on your docking port, click "Control from Here".

Don't worry about aligning. Just get close enough to the docking port. Use I,J,K,L to move down, up, left, and right, H to move forward, and N to move backwards. A good tip is to switch to "Target" mode on the navball, and get your prograde vector onto the target vector. When you get close to the docking port, start aligning. Turn off RCS if it makes it too hard for you. Once you and the docking port are aligned, start moving forward towards it. Remember to keep your prograde and target vector aligned, to be moving forwards towards it.

[Spricigo]

Are you using precise mode (CAPSLOCK) ?

Ok, something to keep in mind: you only need to be 'perfect' at the moment the docking ports touch each other, before that you have time to corrections.

Most docking tutorials (including the training scenario and the video I linked) tell to kill relative velocity at some point. That pause is useful while learning, you did the rendezvous and now will start the final approach. In any case is not necessary and often make the rookie worry to much about it and slowdown to an unecessary crawl. You cannot reach the target if you always stop before reaching it.  Instead I prefer to suggest controlling your velocity. This control is twofold: direction and intensity.

1) Direction is done by maintaining  on top of  (and consequently,   on top of ) , experimenting a bit you will get the hand of to "move the marbles",  the point is: if those markings coincide you're moving directly towards the target if not you will just pass next to it.

2) Intensity is done by burning (either with engines or RCS) in  and  directions. You don't want too slow because your maneuvers to change direction become easy to overdo and thus require corrections (waste of fuel), also we want to meet, more velocity less time to meet it. But we don't want to meet the target at dozens or hundreds m/s. The sums up to what I call 'maneuvering time rule': velocity should be low enough to allow maneuvering but not lower. 

Notice: lower velocities because a safety margin are ok, in fact highly recommend, specially while you are learning. The rule is intended to make docking fast and simple, not some kind of time challenge.

Now, you are struggling with docking,  it's possible your craft may be not very well balanced and your engines too powerfull, so let's start with a maneuvering time of 30s. That is plenty of time to make errors and corrections,  adjust it if you feel overwhelmed or confident to proceed quicker.  Now get an intercept as you already did and when you are about 10km (a safe distance for a rokie, with experience and confidence you may get much closer, among other things because you setup better encounters and you need much less time) away from the target. Make sure the navbal is In target mode. Keep your eyes in the navball, the only re reason you have to look elsewhere is to check the alignment and distance to target except that, all info is in the navball. 

At 10km if you are slower than 300m/s you are within the maneuvering time.  Make  the markers coincide and proceed. As soon as you can switch to the target and align it properly (If you feel necessary slowdown a bit more for this) As you close distance you will notice the markers moving, just keep maneuvering to maintain it in the same place and burn retrograde to keep the velocity within the time (200m/s  at 6km; 100m/s at 3km; 30m/s at 1km...) . While you are far away (10-3km) the main engines are precise enough for the maneuvers, as you get close (3-1km) start to control from the docking port and use RCS, and for the last bit (1km-0) use precision mode. 

There will be moment where you will be well aligned and slower then the 'recommended' velocity. Technically you could accelerate,  but that is not very wise because the unnecessary fuel expent, so use timewarp instead to advance to where further maneuver are needed. 

 

Some considerations:

-I'm not saying this is "the best" method,  rather is a different methods that I prefer. And I share hoping it may be useful. 

-That post contains a lot of 'words' about something much easier to understand with 'images' preferable moving.  I still suggest you watch some videos to see the real thing.

-Docking is actually  'simple' after you 'figure out' what's happening and get used to some techniques.  It's really something that depends on the 'student' take practice and have insights.

-Learning is difficult when you ate tired and frustrated.  When you feel like that go do something else,  relax and try again later.

 

 

 

[Quoniam Kerman]

Thx for those insights. 

Anyway, even if I understand the principles, It is on my nerves that the fault is, so everytime I make a mistake and try to correct it, it just makes the mistake bigger and bigger, it is a general problem with me since the beginning. I usually am much slover than what you advise, speed wise.

As for my ships, I guess I overengineered them in terms of engines and fuel, so I had plenty of fuel left and they are big and heavy so Reaction wheels don't make them turn fast enough to react for an engine burst correction (I was on early career, without full RCS, the capsule I used had a few built in RCS, only on the side for one direction, and truly, not having RCS to "brake" or back off doesn't help !

I hate dumping fuel tanks when there is still fuel in them, but I should have, because I had designed the ship to have a small engine for orbital maneuvers and was still using the main circularising engine, I should have dumpd it to make the ship lighter and more easily steerable by reaction wheels. Even the fuel tank I put on the ship for orbital maneuvers was overkill considering I explicitely diminish engine thrust for such maneuvers down to 1% of nominal in order not to overshoot, I could get way with a few more percent up I guess, like get the thrust up to 5% of nominal would be enough.   Yeah I'm really not confident. I'm the type of guy going to Minmus with a 9000 deltaV rocket just in case I make a mistake and decelerate until 1000 meters from the surface still with the main tranfer engine and dumping it to surface with still some fuel left and activating the ship own engine only for the last slowdown before touch down, helps preserve the possibility of a (more than one) take off and landing elsewhere on the moon for science gathering on another biome quickly, the ship having science data storage containers. When I think I could do a Duna or an Eve mission with that kind of ship... I'd be a waster IRL... I use one stage ships on landing because I'm afraid of not being able to do an Apollo style mission because I hate docking.

On my career, I advanced to RCS rechs now, I'll try to make a balanced RCS ship and this time dump the main engine to make it turn quicker. I'll do it next time I'll have a lab in orbit, when I couldn't do docking on my first little lab, I simply deorbitted everything and launched another one with more assets to be autonomous and not need an orbital supplying mission. I was not lacking money thanks to tourists contracts !

Also I don't know if some of you use the M.O.L.E mod, can you confirm these MOLE docking ports have magnets because they don't seem to. Once the two docking ports just went past eachother but the ships didn't move to stick to each others like I saw on videos. So, either it was because of the additonal weight making the ship too slow to rotate on their own, either the docking ports were farther from one another that I could see (didn't angle camera to see on the top view if they were that close, tbh...)

According to my liquid poor experience, docking is easier the smaller ship you have...

Also, I don't find the IHJKLN key to be practicle, I always mix them up (and also always forget to rotate the ship in the normal way to have directions going in the right direction, I always expect the ship to on the right when I press the right key and forget the ship goes on its right and if it is not in the correct inclination, the ship goes in the wrong direction)

To be honest I find the game controls and interface quite badly designed to begin with, althoug getting used to three dimensional movement can be a bit of a stretch for someone used to bi dimensional movement in video games. The only other space games I own are strategy games and the ships move on their own when you give them commands.

I once tried, in an exhibition about space, a simulation about docking to the ISS with a laser guidance system like the real ships do, I couldn't pull it off even with a laser guidance...  It takes ages, IRL, they take three days to rendez vous with the ISS when they can be on orbit in about twenty minutes... Three days just to change orbit, match plan inclination, get a rendez vous, approach and dock. Most of it is fully automated and even if the astronauts have to check everything is going on as planned, they must get quite bored, stacked in this little tin can... Docking is good for computers and robots (quoting inspired by Obi-Wan here, I guess)