I can not dock ships for the life of me

[theattackcorgi]

Problem: I understand how to get orbit heights and such. But my problem is my ships are orbiting on different plains. one is north to south and the other is southwest to east. I don't know how to move them that way. i know how to increase orbit and dock but not this. Please help as i can not get any farther into kerbal space program until i figure this out. http://forum.kerbalspaceprogram.com/images/smilies/k_huh.gif

[Hodo]

Here you go.

[Rage097]

You can fool about with manuver nodes until you get a close encounter, then when you reach that point in the orbit (after executing the manuver) (and make sure you set the craft you want to dock to as your target) make sure the speed display says "Target". it's showing your speed reletive to the target. you want that to be zero before you progress any further. If the display DOESN'T say target, click the display until it does, then to cancel out your velocity reletive to the target you'll want to burn Prograde or Retrograde. (the icons switch so it's Prograde and Retrograde reletive to your target) after burning and reaching 0 mps in relation to the target, aim at the pink Target marker and burn towards it to get closer. when you're close enough, slow down a bit by burning at the pink marker that means you're facing AWAY from the target. when you feel you're close enough, kill your reletive velocity. then use RCS to try and put the docking ports together.

Good luck!

[Anton P. Nym]

Plane changes to match orbits is fairly simple once you know the trick to it.

- In map mode set the other craft as your target and look for the "AN" and "DN" nodes in yellow. Those mark the Ascending Node and Descending Node, where your orbit crosses the target's. Mousing over the tag shows how many degrees off the two orbits are to the nearest 0.1 degree.

- Set a maneuver node at one of those nodes and pull the purple indicators (which show the normal/anti-normal axis); this will cause the AN/DN nodes to move and display different degrees of inclination. Play with them until you get AN & DN showing less than a degree; ideally you want to see "0" or "NaN" (not a number) as the result.

- Aim your craft along the maneuver node's indicated axis, then burn for the indicated time just like any other maneuver.

- Clear the maneuver node and check the new AN/DN figures to make sure you got it right; if not, set another maneuver at the new AN or DN as above.

- Once the AN/DN show "0" or "NaN", you're in the same plane as your target and now you can work on closing the range.

Plane changes cost a lot of fuel, but once you learn the maneuver node system they're not too hard to plan out and execute.

-- Steve

[Evrion]

- Set a maneuver node at one of those nodes and pull the purple indicators (which show the normal/anti-normal axis); this will cause the AN/DN nodes to move and display different degrees of inclination. Play with them until you get AN & DN showing less than a degree; ideally you want to see "0" or "NaN" (not a number) as the result.

Plane changes cost a lot of fuel, but once you learn the maneuver node system they're not too hard to plan out and execute.

-- Steve

Sounds like what I do, EXCEPT for large plane changes. If one craft is in polar orbit and one in equatorial for example. In that case, play with the purple indicators AND the Retrograde (maybe even prograde) markers.

If you pull only on the purple nodes, then the orbit will get quite a bit larger. For that reason you need to drop the orbit with the retrograde marker. Again, this is only really necessary for significant plane changes, say 15 degrees or more.

edit: and they are expensive! might be better to just end the flight (from the Tracking station) and send up another rocket.

[LameLefty]

The previous responses show how to get your orbits into matching planes to enable a rendezvous (and ultimately, docking). I'll add one point - it's a LOT easier to set up a rendezvous and docking by launching the two vehicles into the same plane, or at least very close to the same plane, to begin with. As noted above, plane change maneuvers take a lot of ∆v and hence a lot of fuel.

As an aside, I'll note that avoiding large plane changes is the main reason why most real-world missions have limited launch windows; they cannot afford the hit to mission performance needed to make very large plane changes. So they avoid the issue entirely by launching in-plane or as close to in-plain as they can manage.

[capi3101]

It helps if you target the craft you want to dock with early - on the pad is ideal if your ship doesn't fall apart in the meantime (which is an indication of other problems that won't discussed here). Check your nodes during your ascent as often as you can; steer slightly northward or southward of 090 to adjust the nodes as necessary. I also find that waiting until the target is 450,000 m downrange of KSC before launching really shortens the time it takes to rendezvous; I can usually affect a rendezvous within an orbit or two.

Okay - so one more time:

1) Launch with the target 450,000 m downrange of KSC. Put your apoapsis as close to the altitude of the target as you can. Fly north or south of 090 slightly to minimize the degree of the ascending/descending node.

2) Watch the encounter chevrons when you're setting up your maneuver node for orbital insertion. If you can get a close encounter, great, but make sure your apses are both out of the atmosphere.

3) Zero out the nodes. This means a burn to the north at the descending node or to the south at the ascending node. Go slow if you're on LOX - a single notch on the throttle is often a bit too much. If you can't zero it out in one go, go as low as you can, stop and try again at the next node.

4) Set up a maneuver node at the next apsis. Dink with the prograde vector and watch the encounter chevrons. If the distance decreases, keep pulling on it until it increases again. If it increases, stop pulling on it and start yanking on the retrograde vector. Get the distance as low as you can.

5) Set up another maneuver node at the next apsis and repeat #4. Expect lesser results.

5A) If playing around with a maneuver node at the next apsis doesn't generate appreciable results, try a maneuver node somewhere between the apses. Be prepared to try a radial adjustment - but don't do those just for jollies.

6) Physics engine kicks in once the target's distance is down to 2,250 m.

You know docking - so I won't go into that bit. In fact, most of this seems to be superfluous since you're just having issues with plane changes, but it might still be useful to someone.

[Ivan Ivanovich]

The foolproof way to lining up crafts. Note that this is NOT the most fuel efficient way to do it, just the easiest.

1. For this training purpose, put a vessel into a 100x100 km orbit (i.e. a circular orbit at about 100km), this will be our "passive" vessel (the one we dock to). Try to make it fly roughly towards 90°, i.e. around the equator.

2. Launch the second vessel (the "active" one) when the other one flies above the peninsula west of the continent the KSP is on, also towards 90°, i.e. towards the east. Make sure this vessel has RCS and quite a bit of surplus fuel. Get it to an orbit of about 110x80km (i.e. apogee 110,000, perigee 80,000).

3. Click on the "passive" vessel and set it as target. A few new markers will appear. Two green markers labeled "AN" and "DN", and two orange and two red markers. "AN" and "DN" is where the crafts intersect in the horizontal plane (i.e. when they switch sides from left to right), the other markers are where the crafts intersect at the vertical plane (i.e. where they switch their "above" and "below" positions), with the two markers representing how far the crafts are apart when this change happens. The dotted line is where the target will be when the active one is at the other marker. Don't worry if you don't get that right away, we'll get to it.

4. Wait for your craft to get close to the next "AN" or "DN" marker, and while you do, align the ship. If you're getting close to DN, aim towards 0 degrees (always at the horizont, i.e. where the navball's blue and orange parts meet, essentially aim your craft towards the north pole and keep it horizontal towards the planet, not pointing "up" or "down"). If you're approaching AN instead, aim towards 180 degrees. When you're close to getting there, gently accelerate. If you mouse over the marker, you'll get a number that represents your orbits' separation. The closer this gets to 0, the less thrust you should apply. When you're at 0.3 or below, you're good enough.

5. Wait for the craft to fly past the next "solid" red or orange marker. I.e. the one where there isn't a dotted line towards the planet. You'll notice that when your craft passes that marker, the target ship will be at the "dotted" marker. When your craft passes the non-dotted marker, you will notice that the dotted marker moves to a new location. This is where your target will be the next time your active ship passes the marker you just passed. Now it's time to adjust the orbit to match up. If the dotted marker (i.e. your target ship) is AHEAD of you, point your active ship RETROGRADE (i.e. against your flight path), if it is BEHIND you, point it PROGRADE. Yes, that means you slow down to catch up and you throttle up to fall back. Orbital mechanics at work, they make sense once you wrap your mind around it. To make it easier, click on the number above your artificial horizon until the word "orbit" appears, then point to the normal green marker on the artificial horizon to point your ship prograde, or the crossed out green marker to point it retrograde.

6. Look at the map, mouse over the marker you just passed (the solid red or orange one) and carefully throttle up. You will notice that the number next to "separation" gets smaller. If it does not, turn your ship around and thrust in that direction instead. You want to get that number down to about 0.4km (400m) or so.

7. Time warp until you've gone almost once again around the planet (i.e. until you're approaching that marker again), mouse over the marker and stop time acceleration once separation reads less than 2000.

8. Click on the number on the artificial horizon again until it reads "target" and point your craft towards the crossed out green marker. Look around, the target should be close (watch out, you might well hit it at some speed...). Thrusting towards the crossed out green marker on the artificial horizon while it reads "target" will reduce your speed relative to your target. Once it reads 0.0 (or close to it, it's kinda hard to get right TO 0.0), you're "standing still" relative to the target craft (although both you and your target zip around the planet at about 2.5km/s.

If everything worked out, you should be about 300m or so from your target. Now throttle up carefully towards the target, wait until you get close enough to see that docking port, point to the crossed out green marker again and zero the relative speed, then it's time to switch to the docking view and do the final approach.

Happy docking.

Edited September 12, 2013 by Ivan Ivanovich