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Nerfherde

A rant about KSP

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Sorry this hasn't helped so far, Nerfherde.

Other planets, I'll use Duna as the easiest example:

- Design a ship with at least 10000 m/s delta V that you can safely get into orbit. Get that ship into a roughly circular 100 km orbit. (I'm just trying to make sure you don't add extra frustration by running out of fuel, here.)

- My all-stock Mars One-Way rover has 11 km/s vacuum delta V, but it's designed for powered landing. It's also ugly and inefficient, but it's an example. https://dl.dropboxusercontent.com/u/2934859/Mars%20One-Way.craft

- switch to map view and zoom way out to where you can see Kerbin and Duna's whole orbits.

- rotate the map view to put Kerbin at the "3 o'clock" position.

- you want to launch when Duna's roughly at the 1:30 position and Kerbin's at 3:00 (for less simplistic terms, when Duna is about 45 degrees ahead of Kerbin. For even less simplistic terms, http://ksp.olex.biz is a transfer burn calculator.)

- So, if you're not already lucky enough to be at that point in the orbits, switch to a landed craft and fast-forward until about that point, then switch back to your interplanetary ship.

- after you've fast-forwarded time to line up the planets, slow it down and exit map view. Fast forward at a slower pace until it's sunset. Set up a maneuver node about 10 minutes ahead of that sunset point, and give it enough prograde to get you out a little past Duna's orbit. Then make that burn - depending on your craft you may have to start it at different times; if it's a 10 minute burn you can start it a couple minutes before you get to the node, if it's a 1 minute burn just start it 30 seconds before you reach the node.

At that point, you should be roughly on your way to Duna. First step is definitely being "close" to the right orbit! Coast until just after you exit Kerbin's sphere of influence.

Then...

- go back to map view and right-click on Duna itself, and set as target.

Important note, if any of this shows a change in SoI on your future orbit, stop and go with that instead of continuing with these instructions. You'll be at Duna when you get there!

- if your orbit isn't showing a closest approach indicator already, you probably either didn't go out far enough, or are angled from Duna's orbit.

- check the green indicators. If they're more than 0.2 degrees off or so, you'll need to correct that. You should already be relatively close to either the ascending or descending node on your orbit. If you're at the ascending, you'll need to burn "south"/"down/normal-" (three different ways to say -normal), if you're near the other you'll need to burn "north/up/normal". Set up a node a few minutes or even hours ahead on your orbit and put in those adjustments until the post-burn orbit shows 0-ish inclination on the green indicators.

- If you're already at a 0 on the green indicators and have no greyish closest approach indicator, try setting up a prograde burn node. The map view can be tricky, and what looks like a far enough out orbit may not be actually crossing Duna's orbit; angle the map view to see duna's orbit from the side of the orbit where you'll be crossing it and see if it's really crossing. set up your prograde burn to take you a bit further out than Duna's orbit, or to get a closest approach indicator.

Once you have that indicator, you're mostly done with prograde burns.

- If the "target position at closest approach" indicator is AHEAD of your "closest approach point" - set up a -Radius (towards the sun) maneuver node. play with adding prograde and -Radius components to the burn; you should be able to use -radius burns to move your encounter point closer to Duna, but it will also be removing distance from your outwards travels so some prograde might need to be added too.

- do the opposite if your closest approach is ahead of Duna on its orbit. mostly +radius burn away from the sun, adding retrograde a bit as needed to keep from heading for Jool instead.

Using that adjustment plus possibly some tweaks to north/south, you should be able to get to a point where you have an SoI change.

Once you fast forward time to within a few weeks of Duna, you can try using the same tricks to lower your closest approach - or you can just brute force a braking burn for a re-entry once you're in Duna's SoI.

Edited by khyron42

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Watch the two below tutorials -- I think they provide adequate information on how to rendezvous and dock. Try it yourself. Next, watch them again. Next, try it again. Rinse/repeat until you get it right! I agree that this aspect is one of the most challenging parts of KSP, but with practice and determination you will get a great deal of satisfaction once you succeed. Make sure you have RCS, ASAS, mono-propellant, and most imporantly have placed your RCS controls at CENTER MASS of your ship -- when using RCS, be sure to TURN ON ASAS or your ship will not move correctly!

Rendezvous Tutorial:

Docking Tutorial:

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I had a problem with docking for the LONGEST time. I could get within range to use RCS (1 or 2 Km), but I couldn't seem to control my ship using RCS thrusters to make it go the direction I wanted. It would invariably start rotating whenever I tried to translate laterally or vertically. The solution was both simple and AMAZINGLY difficult to implement.

1. The MOST important thing is balance. Make sure your RCS is at your ship's center of mass (CoM). And by ship I am talking about JUST the part you are docking without any of the sections that will be used to get it into orbit. When I design a ship, I fully design the docking module and check its balance before I add other stages. Make sure you have RCS pointing in all directions and they are ALL in line with your CoM indicator. (You can turn that on and off in the lower left of the design window of the VAB.)

2. Understand that if you are dealing with fuel tanks on your docking craft, what is in balance in the VAB may not be when you are trying to dock because the tanks are full when you are designing the craft and they are likely to be empty (or partially depleted) by the time you make rendezvous for docking. This moves your CoM. the farther the CoM is from the center of thrust of your RCS thrusters, the more the ship will try to spin as you perform translation maneuvers. You can either transfer fuel from other parts of the ship to try to re-balance everything or you can attempt to counteract spin by applying pitch and/or yaw as you fire RCS. I go for balance whenever possible. It's easier ... for me. As mentioned elsewhere, ASAS and SAS will also help with control issues to some degree, but they can only do so much. Balance is critical.

3. Once you get within RCS range of the target, before you do anything else, reduce your relative velocity to zero.

4. Now for the AMAZINGLY difficult part. Go REALLY slow. I can't stress this enough. And by "slow" I'm talking about "nudging" your craft in any one direction at a speed that will seem only slightly faster than continental drift. Then you wait FOR-FREAKING-EVER (patience grasshopper) until you've drifted as far as you need to in that direction and cancel your relative momentum to the target by firing RCS is the opposite direction. Then you get to repeat the process a LOT until you dock. Keep in mind, your RCS thrusters are not used like rocket engines. You will be firing them in single short bursts. You are not setting a course so much as correcting your trajectory over and over and over and over until you are close enough to target the individual docking port you are aiming for. As you get closer still, your corrections get smaller and smaller until you finally dock. The smaller your course corrections are the easier they are cancel and re-correct. If you are doing it right, you will feel like you are moving somewhat slower than glaciers or software updates. As you get better, your speed will increase until you are going almost as fast as a snail with asthma.

Hope this helps.

Edited by Doc Anderson

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4. Now for the AMAZINGLY difficult part. Go REALLY slow. I can't stress this enough. And by "slow" I'm talking about "nudging" your craft in any one direction at a speed that will seem only slightly faster than continental drift. Then you wait FOR-FREAKING-EVER (patience grasshopper) until you've drifted as far as you need to in that direction and cancel your relative momentum to the target by firing RCS is the opposite direction. Then you get to repeat the process a LOT until you dock. Keep in mind, your RCS thrusters are not used like rocket engines. You will be firing them in single short bursts. You are not setting a course so much as correcting your trajectory over and over and over and over until you are close enough to target the individual docking port you are aiming for. As you get closer still, your corrections get smaller and smaller until you finally dock. The smaller your course corrections are the easier they are cancel and re-correct. If you are doing it right, you will feel like you are moving somewhat slower than glaciers or software updates. As you get better, your speed will increase until you are going almost as fast as a snail with asthma.

Hope this helps.

OK, I gotta correct this one bit. If your ships are oriented north-south, with the ports pointing at each other, then yes, go glacial. Any other time, and your orbits (and bearing!) are are not quite in sync, and when closing 100 m at 0.2 m/s, that's 500 seconds to close--about half an orbit. In that time, while you started off pointed at (and moving towards) your target, all that **** has moved 180 degrees relative to you.

The most important thing I ever read on a forum or video guide was the 1/100 rule: for every 100 m apart you are, close the gap at 1 m/s. 1000 m apart? Close at 10 m/s. 500 meters? close at 5 m/s. This gives you 100 seconds to turn around and stop all motion, and it's not a lot of dv either. importantly, orientation won't change in those 2 minutes. Much, at least. Ever wonder why when you're 2000 m apart and you point at the purple prograde and hit the gas, and 2 or 5 or 10 minutes later you're at your closest approach but instead of kissing you're 300 freaking meters away? Yeah. You orbited out of synch. You'd need to lead the target, and bully to the pilot that can do that. Which brings me to point #2:

Point your docking port on the north/south axis (pointed either to the 180 degree vertical mark on the navball, or the 0/360 one, centered on the horizon line). When you zoom out and look at Kerbin the ship, assuming the port is on the nose, should look like it's pointing straight up and down but flying sideways. Point your docking craft in the opposite direction. Once the docking ports are close to lined up, even if separated by dozens of meters, they will not wobble. Much. I promise. At this point, when you don't have wobble, and ONLY THEN can you move at a glacial pace. I honestly don't know how people do it slowly in any other way, you end up chasing a moving target and never closing the distance.

But your point about ship balancing and RCS port placement is really good--docking really does begin in the VAB.

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Sorry to say OP but you need practice. Get to Mun first. Then land there 10million more times until you can do it with your eyes closed.

Next go to Minmus. Try to go to Mun from Minmus. Repeat ten thousand times

Finally, put a simple ship in LKO with a docking port. Try to rendezvous. Run out of RCS, try to do wth main engine, explode. Repeat ten thousand times.

That is what KSP is all about

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A personal note to Nerherde:

you gotta break down the problem. Think about it this way--the problem can be solved. It might actually be many small problems. Is it a problem with your ship being out of balance? post that craft file (dropbox). Is it a problem with orbital mechanics? You REALLY need to learn how to use the nodes--I cannot stress that enough, and it's so easy to learn, because the nodes don't do anything until you point towards it and start thrusting--so play, trial and error. Is it physics? you REALLY need to understand at least the vector part of physics (motion in any direction in 3 dimensions has an x component, a y component, and a z component--if this doesn't make sense, you need to understand that)--and I say this as a guy who dropped out of intro physics.

Frankly, for all the outpouring the community has shown you, you've gotta give a little back, you know? Give us some data to work with, show us the problem (screen caps or craft files or save files). I tell my friends this is a scientist's game, so you need to be patient and methodical, break problems down, trial and error, determine a problem then find a solution by trying, and lots and lots and LOTS of failure--I cannot stress this enough. Like I said, it took me 80 hours to learn to dock. You'll do it too, but be methodical about it--break the problem down into bite sized problems and address each one in turn. You've provided so little information that I really can't comment on your problem(s) specifically--just one screenshot (which could easily be fixed with NODES). Put up your craft and save files, and an image of your closest approach.

Good luck.

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First step to basic docking: match your orbits. It doesn't matter where your ship ends up in relation to your target ship at this point, just make sure that the two ellipses (circles, nominally) are very very similar. Judging from the picture you posted a couple pages back, that's your first problem. While you might have the same values for the apoapses and periapses, it's so much easier to have them in the same place.

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OK, I gotta correct this one bit. If your ships are oriented north-south, with the ports pointing at each other, then yes, go glacial. Any other time, and your orbits (and bearing!) are are not quite in sync, and when closing 100 m at 0.2 m/s, that's 500 seconds to close--about half an orbit. In that time, while you started off pointed at (and moving towards) your target, all that **** has moved 180 degrees relative to you.

Birrhan, excellent info and I agree with you 100%.

The rate you close on a target needs to be relative to your distance or you're never going to get there. And I really like your approach to setting up both vehicles on north/south headings.

I was mostly making the point (and I was certainly exaggerating the point in my initial post for emphasis) that docking is a fiddly and tedious process and that the most common mistake people make starting out is to rush things. So go slower than you think you need to because, when you are first mastering docking, speed kills. Don't be afraid to take as much time as you need on your approach. The slower you go, the more time you have to work things out.

I didn't talk about the NAV ball because it sounded like they were still dealing with controlled movement with RCS.

Once you have the hang of moving your ship and can get it close enough for a final docking approach, then you're ready to fine tune things with the NAV ball.

At least that's how it worked for me and that's really all I can comment on.

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Let me also suggest that you start with extremely simple ship designs ... as simple as you can get it. Do this just to practice the mechanics of rendezvous and docking. Once you've mastered the mechanics, then you can worry about making your creative design something that can be docked.

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I forgot to say thanks, im a little suprised by the response. Birrhan, i font know if you see that I posted an orbital map of my 2 crafts in orbit yesterday. Orbits I strangely can master hehe. Hmm feel like playing 0.85 again, think I still have that file somewhere...

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I feel the OPs frustration but to be honest OP I suck too but I just keep trying and trying and trying and eventually I make it happen in my own messed up way =)

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I forgot to say thanks, im a little suprised by the response. Birrhan, i font know if you see that I posted an orbital map of my 2 crafts in orbit yesterday. Orbits I strangely can master hehe. Hmm feel like playing 0.85 again, think I still have that file somewhere...

I saw that map, thanks. It looks like you could place a node at one of the two points where the circles cross nearest each other, and drag the blue arrows until your projected orbits get close. Start there, and post a picture of the result. If you're confident, try to perform the burn that the node calculates for you: it will put a blue cross on the navball and a gauge to the right of the navball that has ### m/s, and below that will be a time--when the timer is finished, you need to be aiming at the blue cross (the direction you need to aim), and burn engines till the gauge reads almost zero (the gauge is the amount of thrust you need to add in that direction).

I strongly recommend uploading your craft file too, so we can see how your RCS ports are placed and how they behave. Even a screenshot of the craft would help.

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I remember having such a bad time trying to dock by just eyeballing. then i realized there's a target mode in the navball with relative velocity/target + and -. those and timewarp do make life easier once you get it

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Hey, pebblegarden's videos are no longer private. Cool enough :)

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Have you tried to do what birrhan told you? Tell what's the problem

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Sooo any thoughts?

Well THAT'S your problem.

But seriously, delete all the 6-fold symmetry RCS ports. The only way to ever do RCS--EVER--is 4-fold symmetry.

Also, go back to the VAB, separate the lifter stage, and toggle the center of mass on your orbital craft--then put a ring of 4 RCS ports (1x4 fold symmetry) around the green center of mass ball. Also make sure to add monoprop to your craft--you can never have too much when you're learning. If that whole thing is your orbital craft (yikes!) go small first--just stick with the top bit.

Did you try to mess with the nodes at all? Nodes just predict a course for you--you're not committed to it until you re-orient your craft and hit the gas. I cannot stress this enough. Just try to use nodes to lines the orbits up more or less together. Practice this, and I'll try to recreate your craft when I get home and show you what I mean about the RCS ports (funny enough, there's lots of threads about it but NO PICTURES). This is the closest I could get: HydroTech_RCS_Autopilot.jpg

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Holly Molly, this thread exploded in a short time,

Actually, I think the translation keys (as well as the rotation keys, for that matter) are mapped the way they are because that's how it's done in most flight simulator games, where the keyboard directions correspond to the joystick directions. The "up" key is the same as pushing the joystick forward, which pitches the nose down, while pulling back on the joystick / pushing the "down" key brings the nose up. I've never had problems with the default scheme, but that might be because I used to play a ton of Red Baron as a kid.

Well for what i know Orbiter uses joystick for both attitude and linear control. So it's kind of understandable they would switch up and down for both methods (plane mode) as the stick is in vertical axis in both cases.

But in KSP we use two different controls, one being WSAD or joystick and second IKJLHN. I recently found here that Space Shuttle uses two different sticks for attitude and linear RCS control, just like KSP. And infact UP means UP in linear RCS for the commander seat while RCS attitude control joystick remains in "plane" mode.

Also the RCS stick axis is not vertical but horizontal.

It's good that there are people that like the default method too :). I think control scheme is an important issue in this day and age since people come from vastly different backgrounds, like different flight simulations, real life radio control methods, and many other systems that control many dimensions. I think there should be more talk about different control schemes, and maybe even an choice between them implemented in KSP.

This is where the CHASE mode for the camera comes in really useful. As your ship rotates, so does the camera (so the ship stays fixed on the screen and everything else seems to be rotating instead). This means that IJKL will always move your ship in a consistent direction relative to your screen. Once I discovered CHASE camera mode, it made my docking attempts at least 10 times easier.

Thats true but since we don't have a docking cam and docking ports not always align easily through the main ship axis its sometimes hard (or just not fun) to watch at the ships back while docking ports remain out of view.

With the change to the default control method, i could use any camera angle and instinctively know which button moves in which direction. Also the navball actually stays in CHASE mode the whole time, so we could just use it.

Of course the CHASE mode tip is valid for every control method, so thanks for pointing that out.

[a big snip]

9) Hit "v" until it says "chase cam mode". Look from the back end of your ship. Tap the "I, J,K,L" keys, see which direction your RCS ports thrust. Often times this is not intuitive--"J" may thrust you left, right, up or down, just keep it straight. It's always OK to tap it to remind yourself.

Great tutorial!!

I'll hijack it to add to my point (hope you don't mind me nitpicking).

That's the whole problem of reversed IK controls, they are not intuitive. Now days with IK reversed i almost never tap a button to check directions (unless the ship is rotationally symmetrical so its hard to know where is up just by watching it), especially when i start from behind a ship in chase mode.

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Step one: Get into a circular orbit higher/lower than your target.

Step two: Right-click your target's orbit from the map.

Step three: Make a maneuver node, set it so your orbit's [PE] marker is touching your target's orbit.

Step four: Drag around your maneuver node by left-clicking and holding the circle part of it, then dragging it around your orbit. Watch if your two orange markers come very close together.

Step five: If your orange markers give you an encounter of less than 5km, go to step six. If not, wait until you go around one more orbit and repeat steps 3, 4, and 5.

Step six: Follow your maneuver node, hit f5 on your keyboard. This may be important later on. Double-click the speed indicator on the navball to switch it to "target" mode.

Step seven: When you get close enough, point towards the three-pointed green indicator and thrust until the speed hits zero. If you failed, hit f9 and try again.

Step eight: Point at the pink, four-cornered indicator, and get closer to your target. Slow down before it's too late.

Step nine: Use RCS to maneuver yourself towards the target. Remember to use the IJKL keys to move left, right, up, and down, and the H and N keys to move forwards and backwards.

Step ten: Get close enough to the docking port to get pulled in by it.

Then, you have docked, and your troubles will mostly be over.

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