Tips on orbital rendezvous?? (SOLVED)

[RealKerbal3x]

Hello everyone, I’ve recently been doing my ‘Kerbollo’ Apollo style Mun missions. This is my 1st Mun landing mission and for the last few days I have been trying and trying to rendezvous my kerbals with the command module, but I can’t seem to do it. I’ve watched a few YouTube tutorials, and I’ve even managed to get an encounter within a kilometre, but I can’t get the relative speed below 15 m/s, despite repeatedly using the target/anti target markers. Any tips or help from you more experienced players out there?

Edited January 21, 2018 by RealKerbal3x

[IWanttobeEVA]

Best way is to use the prograde and retrograde markers when you are switched to 'target' in the navball. Choose retrograde and fire until you hit zero m/s. Then you can choose 'target' and then fire toward the craft you're docking with. As you orbit around Mun or Kerbin the vector between you and the target will misalign, so repeat the procedure again as needed until you close. As you gain more experience with orbiting you will be able to figure out the thrust vector you need to keep moving toward the target. At less than 200m I kill all of the momentum and I switch to RCS and use 'H' and 'N' to close the last distance at a few m/s so I don't have to keep flipping my ship around. 

[Vanamonde]

Thread moved to Gameplay Questions, since it is seeking help rather than offering it. 

[GoSlash27]

Best advice I can give:

 1) Set yourself up for success with an intercept orbit. 2) Learn how to "push the ball" in retrograde, "pull" in prograde to keep yourself headed toward the target. 3) Keep your closure rate a function of your distance.

 If you do this and practice it until it becomes second nature, rendezvous is easy.

Best,
-Slashy

 

[bewing]

And then beyond that, rendezvous and docking is the very hardest thing for most new players to learn. There are many little tricks. So yeah, this is a major skill to learn, and it's going to take quite a bit of time and practice.

 

[RealKerbal3x]

Thanks guys!!! Also @Vanamonde thanks.... Haven’t posted on this sub- forum before

[Guest]

I was screaming with frustration when trying to figure out RV and docking. Thing is hard to learn.

Once you've got the hang of it though you can do it in your sleep.

Here's how I do it -- a more detailed breakdown of what's already been said, mostly:

1. Align the orbital planes: fly to the DN or AN, and burn normal at the DN (align your navball with the pink triangle pointing up) or anti-normal at the AN (pink triangle pointing down, with the lines coming out of it) until both nodes read 0.0 give or take 0.1.
2. Set up the RV. Put a maneouvre node somewhere, with enough retrograde/prograde (depending) to give you an intersect; then drag it around until the arrows align, and adjust until the orbits are just touching. Note that sometimes you can't do this in one orbit, so click the +/- markers on the manoeuvre node to check if you can set up a better one some other orbit. If they're really hard to line up, adjust your current orbit a bit to see if it helps. You don't have to be 100% exact at this point, if it's within a km or two it's fine. (Note: If your orbits are close to circular, this is easier to do. I'd recommend starting with these; once you've got the hang of it you can plan encounters from highly elliptical orbits, or even without aligning the planes by hitting them at the DN or AN, but leave that for later.)
3. Execute the burn.
4. Fine-tune immediately: either use RCS H and N or dial the thrust limiter on your main engine, and burn prograde/retrograde in the map view, until you get the markers as close as possible. If it's below 1 km I'm reasonably happy but usually I can get it down to below 0.5 km at this point. Take note of the relative speed of the vessels at the encounter -- it's going to be a completely different exercise if you're doing an RV from Munar orbit to LKO (it'll be around 800 m/s!) than if you're changing orbits around Minmus (less than 10 m/s). High-speed encounters are no different from low-speed ones, you just need to start braking earlier... but to start with, don't attempt an encounter where the relative speed is more than 150 m/s or so.
5. Warp to near the encounter; the closer your encounter and the lower your relative speed, the closer you can warp to. Switch out of map view and the navball to Target mode, and your autopilot to Retrograde. This will get you pointed the right way. 
6. Once pointed at target retrograde, move your camera so you can see your target, and switch SAS to regular mode. You can get up to this point just by following these instructions, from here on out it takes a little bit of practice.
7. Brake as you approach. You're "pushing" the retrograde marker towards the target. I.e., imagine a line from the target marker through the retrograde marker: (x) --- (•). Line up your navball along this line, about the same distance behind the retrograde marker:  V---(x)---(•). Fire your engine: you'll see the retrograde marker move toward the target marker as your relative velocity drops. (If you're going too slow and need to accelerate towards your target, it works the opposite way -- instead of "pushing" the vector, you "pull" it. Try it, you'll see.) The closer you get, the slower you should be going. I like to be going at around 50 m/s at 2 km, 20 m/s at 1 km, 10 m/s at 500 m, and 5 m/s at 200 m at which point it's time to go to the next phase.
8. During the approach phase, when you're below 2 km, switch to the other craft. Find the port where you want to dock, and select "Control from here." Then select the approaching craft as target, and line up its navball with the target marker. This will point the target port at the approaching craft. Note: Docking with an uncontrollable craft is a lot trickier as you can't do this. Don't try it now, leave it for later.
9. If you did everything right so far, you should have your craft approaching each other at around 5 m/s, docking port of the target vessel pointed at the approaching vessel, and a couple of hundred metres distance between them. Make any adjustments you need to get there, and prepare to dock. 
10. Flip your approaching craft so it points at the target craft: line up the navball with the target marker; don't worry if the vector is a little bit off.
11. Switch on RCS.
12. Use IKJL to move the vector up, down, left, and right. Get it lined up with the target marker -- always at the centre of the navball -- and keep it there. As you close in, brake with N (and accelerate with H, if necessary). 
13. Once within 100 m, slow down to 2.5 m/s. 
14. Once within 50 m, slow down to 1.5 m/s and hit the caps lock for docking controls (less jittery).
15. Once within 25 m, slow down to docking speed -- 0.8 m/s. 
16. Once within 10 m, switch off RCS and just focus on keeping the navball lined up with the target marker. 
17. Click!

Note that going too slow in the approach will complicate things: your orbits will be different which means you'll be drifting apart, which means you'll be burning fuel to stay on target. So if you're, say, 5 km away but your relative speed is only 10 m/s and the map says your encounter is going to be a little off, go ahead and accelerate towards the target until you're going at, say, 50 m/s. It'll be easier and cheaper on dV. 

[Rocket In My Pocket]

Follow along with these illustrated step by step instructions; that's how I learned.

[Geonovast]

56 minutes ago, Rocket In My Pocket said:

Follow along with these illustrated step by step instructions; that's how I learned.

I gotta print this out and tape it to the wall next to my desk.  This is not how I've been doing it.

[Rocket In My Pocket]

1 hour ago, Geonovast said:

I gotta print this out and tape it to the wall next to my desk.  This is not how I've been doing it.

Well to be fair; there is more than one way to skin a cat.  I typically link this one to new players because it is the simplest and easiest to understand.

See this full thread for the rest of the illustrations demonstrating all the different approaches.

 

Edited January 15, 2018 by Rocket In My Pocket

[RealKerbal3x]

1 hour ago, Geonovast said:

I gotta print this out and tape it to the wall next to my desk.  This is not how I've been doing it.

Or even better, make it your desktop wallpaper. Then you'll see it every time you log in. Though that might not work as it's quite a long (tall?) image.

Anyway, thanks for the help everyone!!

 

[Plusck]

1 hour ago, Geonovast said:

I gotta print this out and tape it to the wall next to my desk.  This is not how I've been doing it.

Well, @Rocket In My Pocket said that that was how he learned. Which is reasonable enough.

But I really don't think you should try to follow that guide after getting the hang of things. It's hugely inefficient (four different burns in different directions where two should be enough) and highly imprecise (5km is far too distant, unless your rendezvous is many tens of thousands of kilometres away, like a rendezvous in solar orbit or in orbit around Jool).

So, by all means practice with that guide, but you should end up making only two significant burns for a perfect, 100m-distant rendezvous:

- a first burn that makes sure that your orbit actually intersects the target orbit, at the right time to meet the target. You don't need to align planes, just get them to cross (pushing AN/DN around so that it coincides with the target orbit) at the right time so that the chevrons (on that orbit, or on a later one) coincide within a kilometre or two. Sliding the node around will show what's possible with a minimal burn. If you can't get close like that, add a second dummy node after the intersect and see how you'll meet on later orbits. With only slightly more of a burn than needed to cross orbits, you are guaranteed to get a perfect hit sometime in the next few orbits.

- a minor correction about an eighth of an orbit before you actually meet, using target mode to "push the marble" on the navball so that you are in fact heading straight for your target, bringing the intercept down to 0.1km or 0.0km. If you got the first burn perfectly right, you won't need this correction at all.

- a second major burn when you are about 2/3 * n seconds from target, where n is your approach velocity divided by your craft's acceleration, aiming directly at the retrograde-to-target indicator on the navball. Once you get good at this, you can narrow it down to nearly 1/2 * n... but it can get a bit scary and very messy if you mistime things...

 

[xlm]

Like the others said, when syncing speed with target, use the pro/retrograde marker instead of the target marker.

Also, 1km is pretty far, I usually make it less than 200m. If I'm trying to rendezvous with a ship orbiting mun, I usually set up mun encounter and lower the pe on mun encounter all the way on kerbin, and make the orbit almost tangent to the target halfway from kerbin to mun, burn retrograde at periapsis to enter mun orbit and setup encounter at the same time, and fine tune the encounter distance at apoapsis. If the relative speed is too big at encounter, you can get in an orbit closer to your target's, use Kepler's 3rd law to calculate the exact apoapsis you need if you want to rv at n orbits away, and fine tune the rv point at the apoapsis of your last orbit before encounter.

The maneuvers are easy to plan but hard on execution, though. If you don't have a high level pilot or don't want to use one of dem expensive probe cores, you are gonna need mechjeb. If you are not playing career mode then it would be a lot easier.

[RealKerbal3x]

UPDATE:

TL;DR (in the spoiler)

Spoiler

Jeb, Bill and Bob made it home!!!!

The longer answer for those with a larger attention span:

After frustration and many attempts, I have FINALLY made my 1st orbital rendezvous!! (Sorry for no pics, I’m posting this from my phone). After a pretty normal ascent into Munar orbit, and a bit of fiddling with nodes, I got an encounter of about a kilometre. As I got closer, I was worried about slowing my relative velocity. But I found a solution: instead of using the target/anti target markers on the navball, put the navball in Target mode and use retrograde/prograde markers! It worked perfectly and I got my relative speed down to around 2 m/s.

Closing in, I thrust limited my engine to about 5% and slowed down. However, as I got really close, I overcooked a braking burn and went flying in the opposite direction. I turned around and tried again, but of course I overcooked that one as well.

The annoying thing was that this was happening in the ‘night’ side of the orbit. But eventually I got my speed under control, and pointed towards the target, which was about 30 m away.

I switched to the command module, and got lined up towards the target. I then gingerly used H and N to keep moving towards the lander. There were a couple of times where the lander started moving away very slowly, but I kept that in check with RCS. Also, as the SAS was in Target mode, it really helpfully kept me pointed directly towards the docking port. I moved closer, correcting my path as necessary. And as I got about 2 metres away, the magnetism kicked in and......

We docked!!!!

I sat there for a few seconds just staring at the screen, then shouted ‘YES!!!’ I’d done it!!

A quick transfer of crew and fuel later, I made a manoeuvre node that would give me a periapsis of 20 km, well inside the atmosphere. When I did the burn, I even bested that by getting a trajectory that would put me 11 km above the ocean. Then I would get shot out of the Kerbin system, but that would change when we entered the atmosphere.

To make a long story short, we landed safely in the ocean and Jeb got out to have a swim and breathe Kerbin’s fresh air. He took off his helmet (I have the Kerbal Inventory System installed so I can do that). He even stood atop the capsule for a screenshot.

I wouldn’t have been able to do this without you guys, so a big thanks for your help and support. Next I’m going to do an Apollo style Minmus mission, where I’ll use the experience I’ve learned here to reach further and climb higher in the Kerbalverse.

Well, that pretty much sums it up

[Rocket In My Pocket]

Congrats! 

[RealKerbal3x]

15 minutes ago, Rocket In My Pocket said:

Congrats! 

I have a physics test tomorrow, and the funny thing is that I probably know more about orbital mechanics than my physics teacher 

Edited January 21, 2018 by RealKerbal3x

[Geonovast]

1 hour ago, RealKerbal3x said:

We docked!!!!

I sat there for a few seconds just staring at the screen, then shouted ‘YES!!!’ I’d done it!!

You do that a few more times, and you'll be into "How was this ever a problem?" territory.
 

Good job!