[Tutorial] Orbital Rendezvous Made Easy

[VincentMcConnell]

That was from a 100km parking orbit to the 120km orbit?

Yes. LM was in 120, CM was in 100. It would have been the other way around, but I forgot to put RCS on my LM ascent stage...

[VincentMcConnell]

Why do you ask, Kosmo-not?

[Kosmo-not]

Why do you ask, Kosmo-not?

Idk. I just wasn\'t thinking, I guess.

[VincentMcConnell]

Idk. I just wasn\'t thinking, I guess.

Ok. The rendezvous went great, actually. Took a little bit of time and more fuel than it should have because of a few altitude corrections I had to make thanks to KSP\'s warp limitations...

Thank you for sending me that custom chart, by the way. It helped greatly.

My Kerbin rendezvous altitude is always 200KM, so the burn is at 50.5.

My Mun rendezvous altitude is always 120KM, so the burn is 49.5

[Motorsheep]

Hahaa! Managed munar orbit rendezvous today. Took me only two flights. I used circularized my orbits with MechJeb this time though.

Last time, for the Kerbin orbit rendezvous, I used only the orbit info from MechJeb in order to be able to do more precise burns.

So I don\'t know if that counts in y\'all\'s book of achievements..

[VincentMcConnell]

Hahaa! Managed munar orbit rendezvous today. Took me only two flights. I used circularized my orbits with MechJeb this time though.

Last time, for the Kerbin orbit rendezvous, I used only the orbit info from MechJeb in order to be able to do more precise burns.

So I don\'t know if that counts in y\'all\'s book of achievements..

Yes, it counts, but it\'s considered better if you can do it without Mecjeb. In fact, I think I\'ve only done rendezvous with MecJeb once just to try it, but I didn\'t like it because it got in the way of the screen.

[scouseyank]

is there a mod or a way to keep the craft point at the horizon at all times as it travels around the planet?

[Nibb31]

Yes, with the MechJeb plugin.

[Rickenbacker]

This table is awesome! Got me within a few hundred meters of my KSS (Kerbal Space Station) and I managed to eyeball it from there, on the first try!

[Piaer]

Apollo Lunar Orbit Rendezvous. Command Module and Lunar Module.

(photos)

What spacecraft/mod is that for Apollo spacecraft?

And Kosmo-yes, could you also share your spacecraft?

Thank you for the great tutorial

[Tarmenius]

Incredible job (as always) Kosmo-not! Just a quick clarification question about your table: Are the white distances for prograde burns and the grey ones for retrograde? I wanted to make sure I was reading that correctly.

Also, have you tackled the problems with intercepting a target 'behind' you in orbit? I found myself in that situation earlier today with the target\'s orbit at 100km and mine at 80km. It wasn\'t very difficult adjusting my orbits to arrange an intercept, but because it was all guess-work I doubt my method was as efficient as it could have been. Just raised Ap to 120km for a couple orbits, then raised Pe to 98km for a couple more once the target got relatively close. Once I was less than 10km from the target, I matched orbit velocity but from there my rendezvous was a mess. Overshot, then undershot... eventually I got there, though.

Any tips for figuring out which direction to thrust in when closer than 10km but still too far to see whether the target is moving toward or away from you?

[NCC81701]

Incredible job (as always) Kosmo-not! Just a quick clarification question about your table: Are the white distances for prograde burns and the grey ones for retrograde? I wanted to make sure I was reading that correctly.

Also, have you tackled the problems with intercepting a target 'behind' you in orbit? I found myself in that situation earlier today with the target\'s orbit at 100km and mine at 80km. It wasn\'t very difficult adjusting my orbits to arrange an intercept, but because it was all guess-work I doubt my method was as efficient as it could have been. Just raised Ap to 120km for a couple orbits, then raised Pe to 98km for a couple more once the target got relatively close. Once I was less than 10km from the target, I matched orbit velocity but from there my rendezvous was a mess. Overshot, then undershot... eventually I got there, though.

Any tips for figuring out which direction to thrust in when closer than 10km but still too far to see whether the target is moving toward or away from you?

1) White numbers are distances within visual range, Grey numbers are distances out side of visual range. You can\'t see targets greater than 100km. Numbers to the left of 0.0 are retrograde burns, numbers to the right of 0.0 prograde burns.

2) I don\'t quite understand why you are burning to reach 120km orbit when your starting orbit is 80km and your target orbit is 100km. Easiest way to do this is to start in a circular orbit so that when you burn the PE will be where ever you started the burn. Burn until AP is at your target orbit and if you timed your burn according to the table you should get pretty close to your target vehicle once you\'ve reach the AP. Once you\'ve meet up with your target craft, burn prograde again to increase your PE to the target orbit and now both you and your target should be at the same place in the same orbit.

3) The few times I\'ve tried this, 10km is still a bit far to use station keeping burns. If the target is ahead and you are falling behind, I would burn retrograde a bit with RCS so I\'d catch up. If the target is behind and you are moving away, burn prograde a bit with RCS so you\'ll be at a higher orbit and slow down. Once you are within 5km or so you can start using RCS and burn toward the target. Just slight taps and keep monitoring your distances and you should be able to get there.

P.S. Thanks Kosmo-Not, I managed to 'dock' on my 2nd try using your table. I was also wondering if you have any suggestions for trying to rendezvous when the difference between starting orbit and target orbit is greater than 40km? (meaning starting your burn at beyond visual range).

[Tarmenius]

1) Thanks for that clarification... makes better sense now.

2) I was too early on launch and my target ended up a ways behind. Since there was only 20km difference between orbit altitudes, it seemed like a faster solution to set my Ap at 120km (then set Pe to 98km) to let the target catch up.

3) Thanks for the tip, I\'ll give that method a shot next time.

[Abrexus]

Thanks to your amazing guide I was able to dock with my station for the first time! I ran out of RCS fuel and had to use the main engines to close in which was a bit tricky, but it worked!

[VincentMcConnell]

OMG. That space station is awesome! Craft file and list of mods?

[Abrexus]

OMG. That space station is awesome! Craft file and list of mods?

Thanks for the compliment! I still feel very noobish when it comes to designing things.

I made that using the Silisko Industries BACE pack. I will rebuild and post the base for you tonight!

[Temstar]

I made a thread about docking with landing legs here:

http://kerbalspaceprogram.com/forum/index.php?topic=12026.0

Now about those legs. From my experiment that arrangement above is not that good. Together the six legs will prevent any lateral movement between the two spacecraft (within reason, I\'m sure if you really tried you could break them). However they don\'t really 'grip' the opposing ship as such, so if the two ships where to move apart without any lateral movement then the two arms will slip off.

How I thought very long and hard about this and this is the improved docking arm I came up with:

The improvements are:

• 
  [li]Tip of the arm now uses decoupler rather than fuel tank, this is because decoupler seems to have a bulging mid section for the claws to grip onto[/li]
  [li]claws are now placed at the very tip of the decoupler right on the lips, improving length of the grip as well as make the legs close together tighter
  [/li][li]notches are added on the arm to provide some traction for the claws to grip onto[/li]
  [li]increased number of claws per arm from four to six to increase strength[/li]
  

When I get some free time I\'ll try the docking again and see if this makes things better. If it works I\'ll try to connect four spaceships to that station (notice I put a passive 'female' docking arm on the tail end of of that craft). If the improved 'hand to hand' docking turns out to be firm I\'ll try the male-female docking and see how that works. If it also turns out to be a solid dock then Munar Orbit Rendezvous mission profile for Munar landing is a go.

[Zephram Kerman]

@Temstar: If you have any trouble with legs breaking off, you can reinforce them with struts.

[Piaer]

How to make a rocket that lifts such tri wing rendevous module without any perturbations? My rockets keep rotating ... I need something with at least one (3 wings for better look) for better orientation.

[Vanamonde]

AAARRRGH! Pant! Pant! AAARRRGH! I just spent 3 hours trying to rendezvous. It can not be done! You guys who think you did it just imagined it! The attempts drove you insane, and you were delusional.

Kosmo-not, I\'ve read your instructions 3 times and I can\'t visualize them. Is there any way you could make a side-view sketch?

[VincentMcConnell]

AAARRRGH! Pant! Pant! AAARRRGH! I just spent 3 hours trying to rendezvous. It can not be done! You guys who think you did it just imagined it! The attempts drove you insane, and you were delusional.

Kosmo-not, I\'ve read your instructions 3 times and I can\'t visualize them. Is there any way you could make a side-view sketch?

Interesting... I seem to have an entire album containing about 200 screen shots of my crafts approaching various space stations in a rendezvous. I also get the feeling the maybe Apollo, Shuttle, Skylab and Gemini accomplished rendezvous and docking...

[Fulbert]

So I see a topic called 'Orbital Rendezvous Made Easy', I open it to find out how to make an orbital rendezvous even possible for a simple guy like me and the first thing I see is this:

??? ?? ???

[Maraz]

So I see a topic called 'Orbital Rendezvous Made Easy', I open it to find out how to make an orbital rendezvous even possible for a simple guy like me and the first thing I see is this:

??? ?? ???

There are some off-topic messages, unfortunately... please read first post by Kosmo-Not, it\'s very instructive!

Maraz

[Kosmo-not]

AAARRRGH! Pant! Pant! AAARRRGH! I just spent 3 hours trying to rendezvous. It can not be done! You guys who think you did it just imagined it! The attempts drove you insane, and you were delusional.

Kosmo-not, I\'ve read your instructions 3 times and I can\'t visualize them. Is there any way you could make a side-view sketch?

I\'ll see if I can sketch a diagram and post it. Give me a couple days, though.

[Vanamonde]

Give me a couple days, though.

No hurry. Thanks a bunch for doing it at all.

Okay, now I can visualize the video. Thank you.