Docking and rendezvous trouble in KSP & Simplerockets?

[swjr-swis]

29 minutes ago, pandaman said:

2. The strain of launching to get to space in the first place will probably finish me off if I'm that unwell.

But what a way to go, right?

[AlamoVampire]

10 hours ago, Kokanee said:

Hasn't this entire thread been rendered irrelevant by MechJeb?

not really, because people STILL insist that it is cheating, or that they would rather babysit their rockets during long tedious burns or perform the same launch, same rendezvous and same docking a thousand plus times. I will never understand it. I use mechjeb because automation shall set me free!

[rcp27]

I respect the game creator's efforts at producing a particular experience, as a work of art.  If I've tried it and it's too hard, or I've done it and it's become dull and repetitive, fine, but at least the first few times, I think it is important in experiencing the game as intended by the developers to play it "naked" with no mods.

[pandaman]

On 24/12/2015 at 10:40 PM, swjr-swis said:

But what a way to go, right?

Hell yeah! !!!

[The Optimist]

This thread is getting derailed rather quickly.

[Kokanee]

3 hours ago, The Optimist said:

This thread is getting derailed rather quickly.

Edited December 26, 2015 by Kokanee

[Gargamel]

We're not there yet!  It may have derailed, but it hasn't invaded poland yet.

Well, by the time we're to orbital hospitals, I'd like to hope we'd have the space elevator up and running, it'd be one of the few safe ways to transport a patient to space. 

And back to the OP, yes, MJ would be the way to go for him.  I'm a die hard MJ user, but in this case, I'd call it cheating.  I did everything MJ does, manually, at least once before using MJ full time (A few times I had to watch MJ do it to learn it), but if you want to use it as a crutch to avoid learning something new and spectacular (how many of your friends can claim to know orbital mechanics??), then you are only cheating your self. 

 

[Ten Key]

On 12/21/2015 at 0:52 PM, Cloakedwand72 said:

Is any one still having Docking and rendezvous trouble in KSP & Simplerockets?After all the YouTube tutorials etc?

Hi Cloaked. 

I was where you are about a year and a half ago. I found that same Youtube video, watched it all the way through, and came away frustrated. I watched it a second time, and almost missed it again. . .roughly 8 seconds of dialog that solved my problem. 40 minutes of video for eight seconds of dialog is not a very efficient way of conveying information. I feel your pain.

I've never played Simplerockets, so let's start with rendezvous in Kerbal Space Program. I'm going to type out a basic procedure for a simple rendezvous mission-- if any of this doesn't make sense, feel free to ask questions, either in this thread or by private message. We'll get you there.

Set up: First, you'll need a spacecraft. You can use whatever you like, but make sure it has RCS thrusters and sufficient monopropellant reserves. One of the 200 unit monoprop tanks should be plenty. Don't forget the docking port. You will need to be familiar with the RCS hot keys. There are two separate groups: "Q,W,E,A,S,D" are the attitude control keys (which way am I pointed?) and "H,N,I,J,K,L" are the translation control keys (which way am I moving?). I recommend rebinding the translation keys to the numeric pad in the options menu. 

Step One: Launch the spacecraft into a 100 km equatorial orbit. Don't worry if it's not perfect. This spacecraft is the TARGET. 

Step Two:  Let the target go around Kerbin once, until it passes over the launch pad. Let the target get one quarter of the way around the planet, and then launch a second copy of your spacecraft into a 75 km orbit. This second ship is the CHASER, and we'll fly it to the rendezvous. Go ahead and select the first ship as the target from the orbital map screen.

Step Three: Align orbital planes. Unless you got very lucky (or are using something like MechJeb) your target and your chaser are probably not in exactly the same orbital inclination. Think of two hula hoops lying one inside the other, and one of them is not quite flat. In the orbital map screen, you will see two markers "AN" and "DN". These stand for Ascending Node and Descending Node. These are the points where the two orbits cross. Set a maneuver node at which ever one is closest, and adjust either the normal or anti-normal slider (the purple arrows) until the AN/DN markers read 0.0 or NaN. Execute this maneuver. If you overshoot a little bit, use your RCS thrusters (translate forward/backward) to bring the number back to zero. 

Step Four: Rendezvous burn. Because we're in a lower orbit, we'll eventually want to perform a prograde burn to raise our orbit to intercept our target. Go ahead and set a maneuver node somewhere on the orbit, and adjust the prograde slider until the two orbits intersect. You'll see one, and then two pairs of markers appear on the orbital track. These are the points of closest approach. For each pair, one of the markers will have a dashed line connecting it to the orbital track. This is the position of the TARGET. Because of the way we launched, the target should be behind us no matter where we set the maneuver node. Two tricks that the game doesn't tell you-- first, you can drag a maneuver node around on an orbit by left clicking and holding on the circle in the center of the node. Second, right clicking on the circle brings up an additional pair of buttons-- these buttons let you add or subtract orbits from the maneuver. Basically, they let you tell the game to wait a certain number of orbits before setting the maneuver. Try clicking on them and see how they move the intercept markers. Get the markers close with the add/subtract orbit buttons, and then line them up by dragging the node with the left mouse button. You may need to adjust the prograde slider just a little to get the intercept point. Anything within 1 kilometer is acceptable, and anything under half a kilometer is good. Don't try for a "0.0" intercept until you know what you're doing.

Time warp as needed and execute the maneuver. Again, if you overshoot, use your RCS translate forward/backward until the number is where you want it. 

Step Five: Intercept. From this point forward, we don't need the orbital map view anymore-- everything we need is on the nav ball. As you approach your target, the nav ball will switch automatically from orbital velocity to target relative velocity. You can click on the velocity indicator on the nav ball to manually cycle between surface relative velocity, orbital velocity and target relative velocity. Being in target relative velocity mode does two things: first, the #### m/s indicator will now show you how fast you are approaching or moving away from your target, but critically, it will also switch the green "prograde/retrograde" markers on the nav ball to show you the direction you are moving towards or away from your target. This is what was tripping me up. 

Turn your spacecraft so that you are facing the green "retrograde" marker on the nav ball. When you're nearing closest approach (you should have a rough idea of where your closest approach point is from your maneuver burn) throttle up your engine and bring your relative velocity to zero. Doing so will have the effect of very nearly matching your orbit with your target's. 

Step Six: Rendezvous and Docking. Make sure you are comfortable with the RCS translation controls before performing this step. You will need them. Turn the spacecraft so that the gold position arrow in the center of the nav ball is pointing at the pink circle that indicates your target's position. Use your engine or RCS thrusters to burn towards your target until your velocity reads about one m/s. Now, this is where NASA messed up-- there are no straight lines in space. Even light does not travel in a straight line. You are moving towards your target, but along a curved path. What we want to do is to keep all three markers, the gold arrow, the pink target circle and the green velocity indicator stacked up on top of each other. As you approach, use the RCS translation controls (up/down, right/left) to keep the green velocity indicator centered on the pink target circle. You may find yourself slowing down or speeding up as you do this. . .use the translate forward/backward RCS keys to keep your velocity where you want it. Feel free to speed up if it's taking too long, just make sure you have the time and fuel to slow down again later. 

When you're within 200 meters or so, use the bracket [ ] keys to switch to your target spacecraft. Go to map view, and target the approaching spacecraft. Then, use the nav ball to turn your target spacecraft until it is pointed at the chaser spacecraft. Then use the bracket keys to switch back. Keep the velocity marker centered on the target marker all the way home, and it should take you right up to your target. Switch back and forth to keep the two vehicles pointed at each other, and slow down to about 0.5 m/s for the last ten meters or so. Switch off the SAS just before contact. 

 

If any of the above doesn't make sense, feel free to let me know. Happy Holidays!

Edited December 27, 2015 by Ten Key

[Gargamel]

That is waaay too long for the OP to read.