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Brute Force Station Rendezvous


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I wanted to share some rendezvous info that works pretty well for me and might be helpful for newer players also. I'm calling it a "brute force" rendezvous because it's a series of small burns to get you close, not a single exact burn. That's not to suggest that I'm claiming to have discovered this though...I'm sure it's probably nothing new for the more seasoned folks.

If you're like me, you might want to practice in sandbox mode with fuel cheats enabled, put aside all the fancy details (like getting it perfect on the first maneuver) until later, and just do a plain, basic rendezvous to acquire some general familiarity with the whole process. Then move on to dealing the more complicated details like precise maneuvers, fuel efficiency/consumption concerns, etc.

To start with, this rendezvous guide is fantastic and you should already be familiar with the maneuver node intersect indicators he talks about:

His initial burn gets him within 4.7k of the station, but with a real heavy load (or due to certain noob factors on my part), after my initial launch maneuver I usually end up ~50+k away from the station instead. Clearly my launch maneuver was not very exact, but what to do? Revert to the launchpad and try the whole thing again? No!

Assuming you have Target selected in the navball's velocity indicator (not Surface or Orbit) as you should:

1. Turn to face the yellow 3-prong petrograde marker and wait/warp until you are no longer closing the distance to the target. Then burn until velocity shows as close to zero as you can get it.

2. With relative velocity at (or near) zero, turn to face the magenta target prograde marker and burn toward the target. Choose a reasonable speed based on how far away you are.

3. Repeat step 1.

That's it! It will use up a bit more fuel, so you're going to want to get better at reducing the number of burns, but following these steps over and over will eventually get you close to the station. The trick is: do not burn toward the target unless your relative velocity with it is zero, otherwise you might as well be trying to swim in a whirlpool.

Some extra info:

- As suggested in the video, it's easiest to sit on the launch pad and warp until the target station is directly overhead (+/- 20 degrees or so). Then launch. Otherwise you'll want your orbit to be above or below the target so you or it can catch up.

- If you can't seem to get the intersect indicators to move closer together by dragging the maneuver node's prograde vector, then try moving the maneuver node itself to a slightly different location in your orbit. That almost always does the trick for me.

- The further away you are from the station, the more affect a non-zero relative velocity will have prior to burning prograde toward the target. In other words, you burn directly toward the target, but by the time you get there you're way off. So take the time to chase the petrograde marker around and get your relative velocity as close to zero as possible prior to burning toward the target, as it will reduce the total number of burns you'll have to do.

- This should go without saying, but the target's orbit inclination should be 0 degrees to make it easiest. Take the time to get your station into a good, workable orbit before trying to rendezvous with it.

Anyway, I hope this is helpful for anyone else who has tried to follow some rendezvous tutorials and ended up in situations that weren't exactly like the "perfect world" situations depicted in them.

- - - Updated - - -

It wouldn't let me pick How To" as a thread prefix, so I had to pick [Answered].

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1. Turn to face the yellow 3-prong petrograde marker and wait/warp until you are no longer closing the distance to the target. Then burn until velocity shows as close to zero as you can get it.

2. With relative velocity at (or near) zero, turn to face the magenta target prograde marker and burn toward the target. Choose a reasonable speed based on how far away you are.

3. Repeat step 1.

Don't kill your velocity. You can push the retrograde marker on the target's retrograde marker or pull the prograde marker on the target's prograde marker. Look at step 7 of this tutorial: http://forum.kerbalspaceprogram.com/threads/92480-Illustrated-Tutorial-for-Orbital-Rendezvous

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I first started doing what you do instead of starting over, but soon discovered what Harry suggested as a much more fuel efficient way of doing it. It's just a matter of adjusting your course rather than being stopped relative to the target and starting again each time. Sometimes it's difficult when you can't see the markers though.

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Don't kill your velocity. You can push the retrograde marker on the target's retrograde marker or pull the prograde marker on the target's prograde marker. Look at step 7 of this tutorial: http://forum.kerbalspaceprogram.com/threads/92480-Illustrated-Tutorial-for-Orbital-Rendezvous
I first started doing what you do instead of starting over, but soon discovered what Harry suggested as a much more fuel efficient way of doing it. It's just a matter of adjusting your course rather than being stopped relative to the target and starting again each time. Sometimes it's difficult when you can't see the markers though.

You're both right of course, but clearly you're also both quite familiar with doing rendezvous. For people who are not, stuff like that doesn't really make sense yet. It just serves to overcomplicate the whole thing and makes it that much harder to learn the basics. When I was trying to learn, it frustrated me that all the tutorials I found have obfuscated the simplicity of the whole process by adding extra tricks and shortcuts like that. It's like trying to learn simple addition/subtraction by sifting through lessons on polynomials.

What I found easier to digest in the beginning was this simple, 2-step algorithm. That helped me get familiar with the navball markers, the RCS strafe controls, and to know instinctively at any given time what direction I need to burn. Before I had all that straight in my head it was totally pointless for me to try and optimize my approach with advanced techniques and fancy shortcuts. So I posted it for people like me who haven't had that "eureka moment" yet. Take a complex problem and separate it into smaller, more manageable parts. Divide and conquer.

I thought I was clear that this is not the most fuel-efficient way to rendezvous. Just the simplest for beginners, at least in my mind.

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Once you're familiar with the navball it's much easier, yes. Here's the basics of adjusting your course.

Click your velocity so that it shows target speed. This will also change your prograde and retrograde markers to be relative to your target's speed.

Find the locations of the prograde and target markers.

Draw an imaginary line from the prograde marker going through the target marker.

Figure out roughly 90 degrees from the prograde marker on that imaginary line. It can be less, but this will also increase your approach speed, not really a bad thing. Just don't be more than 90 off.

Apply thrust. If you can see the markers, you'll see the prograde marker approach the target marker.

Once lined up, cut thrust and coast.

Repeat.

Using reaction wheels only helps not waste fuel because you can turn to check the markers and thrust a bit at a time if you can't see them. But you should at least be able to see the target marker.

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I am going to have to disagree pushing or pulling your markers does not work well when you are 50km away from the target. I would say zeroing your velocity and checking the map for a proper orbital rendezvous is better. If your behind slow down, ahead speed up. Try to get the encounter around the AN/DN or fix the AN/DN on the way to the intersection.

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I first started doing what you do instead of starting over, but soon discovered what Harry suggested as a much more fuel efficient way of doing it. It's just a matter of adjusting your course rather than being stopped relative to the target and starting again each time. Sometimes it's difficult when you can't see the markers though.

Yeah, this way also make it much easier to learn how to synchronize orbits of ships with very different orbital situation (position) but same period. By altering the Apoapsis or Periapsis (depends on situation which one is more efficient) and moving the node around to achieve encounter after few orbits around celestial body.

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Bleh! That far away, I am still progressing based on orbital period.

Though KAC doe make it trivial to adjust course. Just accelerate along prograde until the closest encounter distance stops shrinking. Then correct inclination and wait a quarter orbit to intercept to fine tune further. I can always get and encounter within 10 m of my target this way.

KAC also makes multiple orbit phase changes more accurate to.

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