Tips and tricks for docking small-large objects in orbit.

[nascarlaser1]

Hi guys!

 

I was wondering if anyone has a link to another forum post with tips and tricks for docking small, medium and large items together in Kerbin orbit. If you have tips of your own I would really like to learn.

 

Thanks!

[bewing]

There have got to be a million tutorials on docking over in the tutorials section. The basics are pretty quick, though. Use standard orbital techniques to generate a close approach. Burn retrograde in target mode until your relative velocity is 0. Turn around and point directly at the target, and burn to give yourself a little closing velocity depending on your comfort zone for closing velocity. Disable the rotation axes on all your RCS controls, so they only work for translation -- this allows you to have SAS turned on at the same time as you are doing your docking. Then use your rcs controls to keep the prograde marker directly over the center of the target marker -- and you'll get a really slick docking every time.

Of course, it helps to flip control temporarily to the target vessel and point the docking port at the incoming vessel.

Edited July 24, 2016 by bewing

[nascarlaser1]

I understand the concept of docking, but my last attempt resulted in the unintentional deorbit of my target ship.... Anyway thanks for the info! This will help me with my ultimate plan to build a giant sphere around the earth, like a giant shell.

3 minutes ago, bewing said:

Burn retrograde in target mode until your relative velocity is 0.

Quick question I forgot to put above. What is target mode and how do I get into it? Also, how do I figure out what my relative velocity is? I can only see my orbital speed.

[bewing]

Your navball should flip into target mode when you get within 60km of your target (after setting some vessel as your target in map mode). If your navball isn't in target mode, just click on the mode/velocity readout (where it says "orbit: 2282 m/s" at the top of your navball). There are 3 modes -- orbit, surface, and target. When in target mode, the velocity it shows is the relative velocity of your vessel to the target.

Edited July 24, 2016 by bewing

[nascarlaser1]

ok thank you very much!

[bewing]

21 minutes ago, nascarlaser1 said:

 but my last attempt resulted in the unintentional deorbit of my target ship....

Yes, this is definitely something to be careful of. If either of the two ships is in a very low orbit and you are maneuvering for a close approach or docking -- a burn can easily put your Pe down into the atmosphere. You have to watch for that, and undo it if you see it happen. The lower the target orbit is above the atmosphere, the more careful you have to be about approaching it.

[Rocket In My Pocket]

I think one of the most important tips is that the direction your nose is pointing and/or thrusting is not the same as the direction you are actually moving.

The prograde marker shows you where you are actually going, if you are thrusting prograde you are basically "pulling" that marker about, if you are thrusting retrograde you are "pushing" it.

So as you are making your final rendezvous procedure, you want to make sure that prograde marker is directly over the target marker. This may require you to switch between a pushing/pulling mindset as you accelerate/de-accelerate. RCS comes in very handy for fine tuning the prograde marker over the target marker as it lets you directly translate it instead of pushing/pulling. It's sort of hard to explain but once it "clicks" with you, you'll get exactly what I'm talking about.

Edited July 24, 2016 by Rocket In My Pocket

[Aethon]

51 minutes ago, bewing said:

Burn retrograde in target mode until your relative velocity is 0. Turn around and point directly at the target, and burn to give yourself a little closing velocity depending on your comfort zone for closing velocity.

When you're within 5 km, instead of stopping completely and burning toward the target, you can push and pull the prograde/retrograde makers to line up with the target marker.  The prograde marker moves toward where the nose of the craft is pointing when you burn and the retrograde marker moves away from where the nose is pointing when you burn.

Also mind your closing speed with the target.  When I'm 2 km out, I try to keep my closing velocity around 20 m/sec.

[nascarlaser1]

I plan on having my dyson sphere at an AP of 300,000 and PE of 100,00 (not very good at making them even) if it helps. I mostly am going to make it out of fuel tanks and other flat objects, and add some crew modules and docking ports :). I will also have 1 hole in it so I can send ships out of the planet like normal.

[Rocket In My Pocket]

1 hour ago, nascarlaser1 said:

I plan on having my dyson sphere at an AP of 300,000 and PE of 100,00 (not very good at making them even) if it helps. I mostly am going to make it out of fuel tanks and other flat objects, and add some crew modules and docking ports :). I will also have 1 hole in it so I can send ships out of the planet like normal.

Not to burst your bubble but there's a hard coded limit to how big something can get given that the physics engine cuts out about 2.5km from the currently controlled craft.

Of course you could  make it up of separate vessels sort of "floating" near each other but I'm not sure how well this will work out. The sheer number of parts involved is likely to turn even the most impressive computer into a slideshow.

I like your ambition, but I think you've bitten off more than you or anyone else can chew. I don't think an actual Dyson sphere is possible in KSP (or in real life for that matter.) Maybe go for a Dyson "swarm" or "ring" instead?

[dire]

My suggestion is start practicing out in high munar orbit, where rondesvous is cheap and easy and the lag won't affect your launches at KSC too badly.

[StarStryder]

On 7/24/2016 at 6:36 PM, nascarlaser1 said:

I will also have 1 hole in it so I can send ships out of the planet like normal.

Also, not technically a Dyson sphere if it's encapsulating a planet.  The whole point of a Dyson sphere is to capture the entire energy output of a star.  Putting one round a planet would both cut the population off from the star's energy while also presenting a sub-optimal surface on the outside for solar energy capture.

Still, a planet circling ring station would be rather cool.

[Tyko]

I did a ton of docking this weekend. It's really fun and satisfying when you get the hang of it. A few things I've learned:

1. First I try to keep my target vessels in at least 125Km orbits - I chose this because orbits can get strange and jittery below 100Km (it's a game bug). By choosing 125Km it allows my approaching vessel space below for faster orbits that are still above the 100Km mark.
2. always remember to select your docking port and "control from here"
3. on target vessel, select it's docking port, "control from here" and point it at the inbound vessel
4. 0.2 m/s is a safe docking speed and it still gives me enough forward velocity that I'm not waiting all day. I always use that speed for the last 20-30 meters
5. If you're open to Mods, the Docking Port Alignment Indicator is just brilliant.
6. Lastly - I have a rule that ships within 100 meters always shut their main engines down before docking - right click on engine and "shut down". I made this rule because there have been way too many times when, after docking I accidentally hit my throttle buttons and the ship pushed my whole station out of its orbit.

Edited July 26, 2016 by tjt

[DD_bwest]

my biggest tip would be top sas on both ships allowing them both to auto target eachothers ports lol   with this, all you need to do is get close, have them both aim at eachother, then gently move your towards it keeping your prograde over the target symbol.    makes it easy peasy.

other tips include,  turning rcs power much lower on smaller ships,  and if our rcs nozzles are off center, consider turning off sas in the last 5m to let the ports do the work.

[steuben]

On ‎2016‎/‎07‎/‎24 at 1:36 PM, nascarlaser1 said:

I plan on having my dyson sphere at an AP of 300,000 and PE of 100,00 (not very good at making them even) if it helps. I mostly am going to make it out of fuel tanks and other flat objects, and add some crew modules and docking ports :). I will also have 1 hole in it so I can send ships out of the planet like normal.

Dream big launch big. But given those orbit specs I don't know that you will get a Dyson sphere, maybe a Dyson ellipsoid. Assuming physics still works... would be an epic failure to watch though if it doesn't.

Edited July 26, 2016 by steuben

[nascarlaser1]

Thanks for all your help guys... My computer died not long after I got half of a ring around the planet.. :(.. there goes that project. As for practicing in a munar orbit, my last 2 attempts at getting anywhere close to them mun resulted with me either shooting past it into the sun's orbit, or with me failing  to understand what "mun encounter" meant in map view and promptly smashing into the surface at escape velocity.... I think I'll stick with looking for the Kerbin north pole flying saucer easter egg for now... thanks anyway!

[bewing]

1 hour ago, nascarlaser1 said:

 or with me failing  to understand what "mun encounter" meant in map view and promptly smashing into the surface at escape velocity

lol! Of course, you did understand correctly -- but there is also a rock there that you need to make sure you dodge, and you have to look extra closely at the map view to know whether you need to dodge or not.

 

[nascarlaser1]

1 hour ago, bewing said:

lol! Of course, you did understand correctly -- but there is also a rock there that you need to make sure you dodge, and you have to look extra closely at the map view to know whether you need to dodge or not.

 

The map said "mun encounter", and then "mun escape" so I assumed I was doing a fly by. I time warped while in map mode, a few seconds before mun encounter I switch back, and I see the ground rushing at me at a good 400 m/s.... rip my pilot.

[bewing]

Yes -- the other vastly important thing you need to see is a Munar Pe.  

[Spricigo]

So you missed the fact that the line between Mun encounter and Mun escape crossed Mun surface.  Or,  as stated by bewing,  Mun Pe was inside Mun.  (Mun Mun Mun Mun Mun....Mun) 

Mun always wins the chicken game. 

[LN400]

Possibly the biggest breakthrough I ever had when it came to fine maneuvering was to have a dedicated set of keys (through the controls setup) for anything translation using RCS (look for translation movement in the ship control section). My setup (for whatever that is worth) is

Forward H

Back N

Arrow keys where up = up, left = left etc

You may find a different combo that suits you better.

The distance between the H/N and the arrows makes it easy for me to have full control over translating movement.

 

This made a world of difference for me when it came to steering the prograde/retrograde markers around on the navball. Mind you, the slower you move relative to the target, the more efficient the key presses (and fuel consumption) become.

[nascarlaser1]

19 hours ago, Spricigo said:

So you missed the fact that the line between Mun encounter and Mun escape crossed Mun surface.  Or,  as stated by bewing,  Mun Pe was inside Mun.  (Mun Mun Mun Mun Mun....Mun) 

Mun always wins the chicken game. 

When I was seeing this the mun was still on the other side of the Kerbin. That's why I was time warping. When I cam out of time warp it was too late :(.

[FullMetalMachinist]

1 hour ago, nascarlaser1 said:

When I was seeing this the mun was still on the other side of the Kerbin. That's why I was time warping. When I cam out of time warp it was too late :(.

When you intercept another body's SoI (in your case, the Mun encounter and Mun escape), you can focus the view on that body in map mode and see what your current trajectory through that SoI is in between the encounter and escape points. 

So what the others are saying is that when you saw that you had an encounter, you should focus on the Mun and see what your orbit will look like once you enter it's SoI. If it turns out that your orbit line passes through the Mun (PE inside or under the surface) then that means you will crash into it. 

The good news, is that while you're focused on the Mun, you can still control your ship. This means that you can place a maneuver node just ahead of where your ship currently is, and see how that node will affect your orbit around the Mun in real time. You can then thrust radial or prograde/retrograde as needed to get your Munar PE above the surface. 

[nascarlaser1]

 

24 minutes ago, FullMetalMachinist said:

When you intercept another body's SoI (in your case, the Mun encounter and Mun escape), you can focus the view on that body in map mode and see what your current trajectory through that SoI is in between the encounter and escape points. 

So what the others are saying is that when you saw that you had an encounter, you should focus on the Mun and see what your orbit will look like once you enter it's SoI. If it turns out that your orbit line passes through the Mun (PE inside or under the surface) then that means you will crash into it. 

The good news, is that while you're focused on the Mun, you can still control your ship. This means that you can place a maneuver node just ahead of where your ship currently is, and see how that node will affect your orbit around the Mun in real time. You can then thrust radial or prograde/retrograde as needed to get your Munar PE above the surface. 

Thanks. After a few more tries of just pure luck I will probably start another thread asking someone to explain it in better detail for me. Hopefully my pure luck will work, and I'll be able to land finally on my own. If not, there's always the community!

 

Also, hasn't this thread gotten a tad off topic :P....

Edited August 1, 2016 by nascarlaser1
This thread is off topic lol.

[Tyko]

If you're plotting a planet or moon encounter just get yourself ANY kind of encounter, then left-click on the planet/moon and select Focus View. Now you can zoom in on the target body and see exactly where your encounter path is.

If you're open to mods, Precise Maneuver (amongst other things) will map keyboard buttons to the six directional arrows on the Maneuver Node. Using those 6 buttons you can tweak your Node while your in a close-up view of your planet/moon.

Using this method, it's really easy to nail precise flybys or put yourself in an exact orbit.