Help! Rendezvous

[Sgt]

Hello all!

So I have been playing KSP for a day or so now, and unfortunately I can't seem to get past the Docking training.

I have:

-Set the stranded ship to target.
-Added new maneuver node (near the ascending, correct?)
-Adjusted ascending and descending so the 'angle' or 'degree' is that of the stranded ship (still trying to understand this).
-Executed successful burn.

Here's where I'm getting confused (and please bare with me):

-Added new maneuver node (anywhere?)

From what I understand the idea is to get the 'two orange intercept icons' to meet up within 5km of each other? This is accomplished by... adjusting the prograde and retrograde icons, AND also adjusting the node location? (Wow!)
What are the 'two pink intercept icons? Do they need to meet up as well?

After 2+ hours of attempting it I resorted to searching for YouTube videos, but still can't wrap my head around it. But I am defiantly still feeling optimistic and want to nail this!

Sorry I don't have any screenshots or more information! If anyone has any additional links to helping me understand this better, it would be much appreciated!

[paulprogart]

I remember this tripped me up too... the tutorial doesn't quite do a thorough enough job of explaining it I think.  (Though it's otherwise pretty good.)

Add the new manoeuvre node and adjust it until you get it close to the target orbit.  If you get it close enough to the target orbit to intersect you'll get an orange set of markers.  One shows where the intersection is, the other shows where the target is at intersection.  This is why you want them to line up - you want the target to be there when your ship is.

Now if your projected orbit just touches the target orbit, that's all you'll see.  However, if your projected orbit crosses the target orbit, you will have two intersections (two arcs crossing at two points), and that's when you see the pink set of markers.  The pink set is the second intersection.

You only need one set (pink or orange) to line up, and indeed only one ever will unless you're already practically matching the target orbit.  You can pick either one at this stage.

Yes it's a lot to coordinate but it gets easier with time.  Also it helps to remember to use the mouse scroll wheel (hover over one of the node handles) for fine-tuning.

I don't remember the exact details of the tutorial but yes I believe the node can pretty much be anywhere.  Placement will affect efficiency but at this stage you don't care about that, you just want a rendezvous.  So as long as you don't lower your course to get into Kerbin's atmosphere or anything like that you're okay. 

Edited March 9, 2017 by paulprogart
clarification, because I never explain properly on the first go

[Sgt]

35 minutes ago, paulprogart said:

I remember this tripped me up too... the tutorial doesn't quite do a thorough enough job of explaining it I think.  (Though it's otherwise pretty good.)

Add the new manoeuvre node and adjust it until you get it close to the target orbit.  If you get it close enough to the target orbit to intersect you'll get an orange set of markers.  One shows where the intersection is, the other shows where the target is at intersection.  This is why you want them to line up - you want the target to be there when your ship is.

Now if your projected orbit just touches the target orbit, that's all you'll see.  However, if your projected orbit crosses the target orbit, you will have two intersections (two arcs crossing at two points), and that's when you see the pink set of markers.  The pink set is the second intersection.

You only need one set (pink or orange) to line up, and indeed only one ever will unless you're already practically matching the target orbit.  You can pick either one at this stage.

Yes it's a lot to coordinate but it gets easier with time.  Also it helps to remember to use the mouse scroll wheel (hover over one of the node handles) for fine-tuning.

I don't remember the exact details of the tutorial but yes I believe the node can pretty much be anywhere.  Placement will affect efficiency but at this stage you don't care about that, you just want a rendezvous.  So as long as you don't lower your course to get into Kerbin's atmosphere or anything like that you're okay. 

Thank you Paul!

This is a huge help, along with Scott Manley's videos.

I've read that it's taken players some serious time to get this right!

[FullMetalMachinist]

21 minutes ago, Sgt said:

I've read that it's taken players some serious time to get this right!

Yep, the general consensus is that it's one of the hardest things to do learn in the game. So if you're trying to tackle it after only a day or two, then you're much braver than I. 

Anyway, another couple of things that might help. I know of two good docking tutorials here and here. Hope these help. 

Edited March 9, 2017 by FullMetalMachinist

[Sgt]

8 minutes ago, FullMetalMachinist said:

Yep, the general consensus is that it's one of the hardest things to do learn in the game. So if you're trying to tackle it after only a day or two, then you're much braver than I. 

Anyway, another couple of things that might help. I know of two good docking tutorials here and here. Hope these help. 

Wow! Huge help.

Thanks FullMetalMachinist.

[HebaruSan]

It sounds like you've got the basics. There are three (or six) ways to miss your target: You can be north or south of it, you can be above or below it, and you can be in front or behind it (or any combination). Each of these can be compensated for with one of the drag handles or by moving the node, but it isn't always easy to tell which handle will do what. The "coplanar" step that you've already done in the tutorial solves the north/south direction for you, and making the lines touch addresses above/below. So all that's left is to make sure you're not too far ahead or behind the target, which is most easily done by adjusting when you leave your starting orbit.

(I just tried this tutorial, and for what it's worth, I normally would not bother with that coplanar step. I'm a fan of bringing the AN or DN together with the orange intercept markers for a <0.5km intercept, coasting to about 45 seconds before closest approach, and then burning retrograde in target mode to keep the time-till-closest-approach around 30-45 seconds, till target-relative velocity is under 10-20 m/s. That final step will take care of any needed plane changes for you automatically. Typically when I drop out of map mode, my target is floating serenely a few dozen meters in front of me. Maybe something to try once you feel comfortable doing it the tutorial's way.)

[Sgt]

Update!

I was able to get past the first part of the docking training - using the normal and anti-normal maneuver nodes to aline the rescue ship's orbit with the stranded ships orbit (wow! I'm starting to sound like I know what I'm doing lol).

After adding a new maneuver, and FINALLY (somewhat) understanding the concept of lining up the intercept icons, the Next button lit up! Although I'm still not done, it took me 2 days to come this far lmao.

I am a little confused again now, after executing the burn the ships still didn't intercept properly (even though the distance between ships said 3-4km before the burn).

Tomorrow is a new day!

[bewing]

The intercept in that tutorial is very delicate. A tiny bit of extra speed results in a big difference in distance. When your burn is almost complete, it's best to shut the engines down and then do the last little bit of the burn in puffs -- watching the intercept markers, and not the dV gauge. If you go a teeny bit too far, then you can turn around retrograde, and burn a tiny puff that direction.

Once you've traveled nearly to the intercept point, there are other little maneuvering tricks that you will find in tutorials that will get your intercept very very close.

 

Edited March 10, 2017 by bewing

[Sgt]

Update............

My throat is sore from yelling so much. Feeling defeated! 

[HebaruSan]

9 hours ago, bewing said:

it's best to shut the engines down and then do the last little bit of the burn in puffs -- watching the intercept markers, and not the dV gauge. If you go a teeny bit too far, then you can turn around retrograde, and burn a tiny puff that direction.

I like to lock prograde, rotate till the red north line is on top of the nav ball, and then turn on RCS and fine tune with the HNIJKL keys. Pick a direction and press it very briefly; if the intercept gets closer, keep going, if it gets farther away, then try that direction's opposite. This technique gave me a 0.0 km intercept for this tutorial.