Sign in to follow this  
bflave13

Trouble matching orbits

Recommended Posts

Hi everyone, I'm new with KSP. Im trying to get started by building a fueling station in Earth orbit but I have such a hard time getting their orbits to match up so I can add on. Any advice?

Share this post


Link to post
Share on other sites

How are you missing?

If you're arriving too soon or too late, save the game, launch to the target's orbital height and note the time that takes, then load your save and launch when the target is that far east of KSC.

If you're missing north/south, is the target on an equatorial orbit?

It very much depends on what the specific situation is. Can you give us more information?

Share this post


Link to post
Share on other sites
Hi everyone, I'm new with KSP. Im trying to get started by building a fueling station in Earth orbit but I have such a hard time getting their orbits to match up so I can add on. Any advice?

Assuming station is in prograde equatorial orbit:

One way of doing it would be to launch "ahead" of your target.

1) launch 1/6 orbit or so before the target passes overhead KSP (the closer to the target, the less d/v you need.. but no biggie)

2)Raise your apoapsis to that of the target orbit

3)Coast to apoapsis

4)Burn at apoapsis until your closest encounter is as good as it will get (if inclination is matched it will be <1km). This will give you an elliptical orbit with an apoapsis higher than that of your target.

5)Match inclination by burning in normal/antinormal direction at the first ascending/descending node

6)Coast to Apoapsis. Here you can use RCS to do any fine adjusting either prograde or retrograde. It will take slightly more d/v, but you have more control. Any close encounter <5km can easily turn into rendezvous, but elegance demands <200m.

7)Coast to closest encounter. Change velocity view from "orbit" to "target". Burn at retrograde marker until 0. Then point at target, burn again until relative velocity is 10m/s or so. Then coast until new closest encounter, point retrograde and burn till relative velocity is 0. Rinse and repeat.

<EDIT>

the benefit of said method over a direct rendezvous in the first orbit is the much lower need for accuracy. for a direct approach you need to launch at a fixed time, and use a fixed ascent profile. You can somewhat modify the launch window depending on the ascent profile.. But if your struggling you will more likely than not miss. That gives you a scenario where you will take several orbits anyway.. And likely use more d/v as well. The two orbit method not the most elegant.. but it is probably the most idiot proof.

Hope that at all made sense/was a tiny bit helpful.

Edited by plausse

Share this post


Link to post
Share on other sites

Is this an illegal station IRL? You did say "In Earth Orbit" :)

Besides that, I have a tutorial on everything you need, there's a link in my signature. Check it out.

Share this post


Link to post
Share on other sites

Wow a fueling Station around Earth? Didn't heard anything bout your station on the news! Naaaaawww just kidding :P

So first: Welcome aboard, Kerbonaut!

You should check out some Youtube Vids to get a good sense about orbital mechanics and docking, also you may try the ingame tutorials, helped me a lot.

Now go an conquer the solar system for whole kerbalkind! :)

Share this post


Link to post
Share on other sites

I usually don't do a direct rendezvous, I just wait to launch until the target is right over head or just a little before. It usually takes about 3-4 orbits to rendezvous. I use a similar method as plausse described above.

-First set apoapsis to match your target

-Then coast to the apoapsis and set your periapsis accordingly (make sure you have actually targeted your target first so you see intersections and inclination)

* If you are behind your target set periapsis slightly lower than target

* If you are ahead of target set periapsis a little above your target's

-Then correct your inclination at the next inclination node (it helps to use a maneuver node here so you know which way to burn)

-Warp time and orbit while monitoring your separation at each intersect (Seperation should be decreasing)

-When you see your positions flip flop burn either prograde or retrograde (depending on if your periapsis is higher or lower than targets) until your intersect closes to less than 1 km

-Approximatley 1/4 orbit before your intersect switch your navball over to target mode and burn towards your target until prograde indicator is inside your target indicator (you actually burn off to one side of the target node to do this)

-Flip retrograde and burn to reduce your speed in relation to your target.

-Repeat last two steps until prograde indicator is inside target indicator and you have an intersect of 0.0 km.

-Inside of 1 km from target switch to RCS and begin thrusting retrograde to bring your speed down. By the time I'm 100 meters or so out I like to be under 5 m/s. Keep the prograde and target indicators lined up.

That's about it. Then you just have to dock

Share this post


Link to post
Share on other sites

Here are 2 separate tutorials for learning how to dock,they are by the same person (Scott Manley).You can go to his channel for more KSP tutorials,I find them very educational.

Share this post


Link to post
Share on other sites
This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this