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# How to get into stable (not changing height) orbit??

## Question

Can someone tell me please step by step and using vanilla parts how I can put a rocket in stable orbit (stable as not going up, not going back to Kerbin) and still being able to gett back when I want to return to the surface? My best attempt at the moment ended with the three kerbalnauts flying to the emptiness of the space, they\'re still flying around lol

Will really apreciatte it.

Thanks.

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Okay let\'s layout some terminology so that we can be perfectly clear what you\'re trying to accomplish.

You said your bet attempt ended with flying into the emptiness of space.

That\'s a hyperbolic trajectory.

An Kerbal orbit would be a circular/oval trajectory around Kerbin.

When you get an orbit around a planet, there\'s an elliptical orbit and a circular orbit.

Kinda self-explanatory.

A circular orbit is a perfect circle,

an elliptical orbit is an oval, or ellipse.

I\'m not quite sure if you\'re asking how to make any type of orbit, or if you want a very circular orbit

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I want to orbit Kerbin indefintely withou falling to the surface or flying to the empty space. Just like our satelites. I don\'t mind If is elliptical or circular. Once I\'m tired of staying up there, I want to know how to come back.

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1. Fly up to about 50-60,000 m

2. Fly sideways and press m, wait until you have a periapsis and an apoapsis, with the smallest height of either being 70,000

3. Wait until you are at either the Apoapsis or the Periapsis.

4. If you are at the Low point of orbit, you will be moving faster, turn your craft to the green circle with x on the nav ball and fire your engines, go to the map by m again and wait until you have an almost perfectly circular orbit.

5. If you are at the high point of orbit, you will be moving slower, turn your craft to the green circle with no x on the nav ball and fire your engines, go to the map again and wait until you have an almost perfectly circular orbit.

6. Mission accomplished.

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Here\'s how I do it.

Going Up

0, Activate SAS and press M for map and raise the navball so you aren\'t fumbling for it later.

1, Launch at full throttle.

2, When you reach 12,000 meters, tilt right so the V indicator is on 90 degrees on the navball, halfway to the orange part of the navball.

3, When you reach 24,000 meters, tilt right again so the V is between the 90 and the line where the navball turns orange.

4, Go to the map screen and watch your Apoapsis marker, press X when it gets to 75,000 meters.

5, Coast until near to the Apoapsis marker, tilt to the blue/orange dividing line and fire your engines until the Apoapsis and Periapsis markers flip around, press X, you are now in a stable orbit.

Coming Down

When ready, point in the opposite way you are traveling ( the green marker with the X is pointing the way you came from ) and fire your engines until your Periapsis is below 35,000 meters.

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Here is a great step by step guide to get yourself in to orbit, made by my favorite astrophysicist.

It\'s an older video, but nothing has changed in the ability to do this. He has made many other video\'s that you might like to check out.

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I think my problem is controlling the rocket direction so it properlly do what\'s shown in the video, specially the part where you aim to the Peryapsis. Need to keep training, maybe someone have a tip?

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It helps to watch the nav ball more closely than the animated rocket. In other words, the camera angles look cool but make navigation confusing, while the nav ball is always properly oriented.

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Yes, I\'d highly suggest watching a video or two, and then make sure you focus on using the NavBall.

I\'ll tell you right now that without a NavBall, I could attain orbit 20% of the time optimistically speaking.

And they wouldn\'t be very pretty orbits either.

NavBall shows you which way your facing, where your apoapsis/periapsis is and a few other goodies. It makes a world of difference once you learn how to use it.

It\'s not tough, but there\'s a bit of a 'getting used to it' time period.

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The navball shows your prograde and retrograde directions on your orbital vector. You need the map to see your apoapsis and periapsis (but you can see them on the altimeter, they are the points when you stop going up (or down) and start going down (or up).

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The flying using the navball is a must. Using that and the help from youtube tutorial author I got my first orbit today!

Thanks a lot to all.

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Hi

Maybe you should start with using MechJeb. It will make you familiar with three steps of orbiting and so on.

It\'s a long time to recognize all the nuances of advanced orbiting, but here are my three 'rules of thumb':

1) to raise your Apoapsis, warp till your Periapsis and then burn Prograde (according to RealDarko, it is a must using the navball, it will really simplify your life. I guarantee.)

3) To lower your Apo/Peri -apsis, warp till the opposite end of the orbit and then burn Retrograde.

Good luck,

Shaun

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What\'s MechJeb?

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Most complicated but also most easy-to-use plugin ever. LINK.

It\'s (not only) an autopilot that can do almost everything for you.

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Wow! Looks like an amazing MUST HAVE!

But have some questions.

- Can the autopilot control any kind of rocket? Even big ones carrying satellites?

- Can MechJeb send me to the Mun and back in one piece?

- Can MechJeb be adjusted so you can meet other pieces in the space?

Thanks!

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Yes, but the rocket should be able tu fly . However, the rendezvous part of MJ is new, and I had no chance to try it out for now. (I think it is not really for meeting up but can be used. You can also configure the ascent autopilot to launch exactly when you whould meet the other ship in space)

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What about the Mun part? Can MechJeb, put me in orbit, then send me to the Mun and back?

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Yes, but I don#t know how. I\'m terrible at flying anything.

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MAYPS! MECHJEB Ain\'t Your Personal Slave!

1) It won\'t take your ship right to the Mun, actually. There is no Mun button.

2) But there is an oldschool trick, invented by a very talented astrophysist that plays KSP. You get into a near-100km orbit (MechJeb is designed for delivering you to a perfect 100km orbit with just one button) and wait till the Mun rises, than you burn prograde*. I advice you to use map for this burn. You go to the Map view (key 'M'), unfold the navball (the tab just in the bottom of Map view) and burn prograde until the curve of your orbit touches the line of the trajectory of the Mun. Then IMMEDIATELY press X to cut off your engines.

3)The next step is landing, it\'s a bit more complicated, but I think it\'s easy with the MechJeb, that shows you your TRUE altitude over the Mun (tab 'Surface Information'). If the Mun is trying to literally kick your ass, IMMEDIATELY burn retrograde and easily kiss the surface with your landing legs.

4) ??????

5) PROFIT!!!!!!!!

Sincerely yours,

Shaun.

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I did not say that Mechjeb can bring you to the Mun with one click, I just wanted to say that it is damn easy with Pro/Retro orientation and Landing/Ascent autopilots...

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Actually, with v1.8 and the transfer function in the new orbital operations section for MechJeb, it can put you into orbit around the Mun with one click to transfer and another click to circularize.

So yes, there is a Mun button.

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Actually, with v1.8 and the transfer function in the new orbital operations section for MechJeb, it can put you into orbit around the Mun with one click to transfer and another click to circularize.

So yes, there is a Mun button.

Isn\'t that technically two buttons for the mun?

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Jeeze, all this talk of Mechjeb, it\'s getting to the point where you may as well just press play on a youtube vid of a Mun flight

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It\'s a crutch.

I split this post up into sections to make it a little easier to 'take in.' Warning, walls of text.

The planet of Kerbin orbits in such a way that taking off into the east is easiest as the planet\'s surface will help 'launch' you forward. This is because with reference to the poles, the planet\'s surface is always moving about 140m/s to the east.

The top of the atmosphere of kerbin is at 69100m. If the lowest point of your orbit is not above this height, you will have some atmospheric drag which will slow your ship back down.

So, to help you understand basic orbiting... think of an orbit this way.

If you\'re throwing a tennis ball, it\'ll fly a short ways before gravity succeeds in pulling it back to the ground. As you throw the tennis ball harder and harder, the tennis ball will have more and more horizontal travel distance before it falls back to the ground. If you throw it hard enough, you can get the tennis ball to fly horizontally far enough that the curvature of the planet starts to come into play, and it\'ll 'fall' at the same rate that the ground is 'falling away' from it.

So, as you have more horizontal speed, you can 'fall' around the planet a little further and further. If you have enough horizontal speed, you\'ll 'fall' so fast that you\'ll actually ascend.

You\'ll have the most effect on your orbit by either facing directly parallel to your path, or directly perpendicular to it. If you are facing along your path, the two key points are the Apoapsis and the Periapsis (Ap and Pe).

These are the two key points for accelerating or decelerating your ship to have the most effect on your orbit.

If you accelerate at the Ap, you\'ll increase the height of your Pe and get a rounder orbit. If you accelerate at your Pe, you\'ll get a more oval (more eccentric) orbit that will extend further away from the body you are orbiting. If you decelerate (or accelerate backwards) At your Ap, your orbit will become more eccentric and your Pe will decrease height. If you decelerate at your Pe, your Ap will decrease height.

In general, acceleration at x will increase the height of y. Decelerating at x will decrease the height of y.

If you do a burn perpendicular to the path of your orbit, you will be able to change the path the orbit goes around the planet. If you are initially orbiting the equator, you can make your orbit shift towards the north by accelerating north. The same effect can be achieved by pointing south. Your orbit\'s path ahead of you will shift north or south, respectively, while the orbit path behind you will shift in the opposite direction (Newton\'s second law: equal and opposite reaction).

WATCH YOUR AP AND PE HEIGHTS AS THEY CAN 'SLIDE AWAY' FROM YOU IF YOU ARE NOT ALWAYS PERPENDICULAR TO THE PATH OF YOUR ORBIT.

A completely round orbit is almost impossible to achieve in KSP as there are slight rounding errors that will always take effect. Although, in all practicality, you can get the high and low points of your orbit within 5% of each other.

Make small changes, it doesn\'t take much to make a large effect when you\'re in space. Remember, there are no 'reactive forces' in space, such as drag and friction. If you accelerate, you\'ll accelerate until you quit applying thrust.

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I\'m not sure whether it\'s a good thing I don\'t use Mechjeb, or a bad thing a lot of others seem to. Sure, it takes more practice, but I\'ve managed several Mun landings just using a totally stock game, including all parts... Mun orbits and free-return trajectories are just variations thereof (as in, not hitting the Mun at first instead ). Using Mechjeb just seems to me like a waste of time -- it\'s far more fun (in my opinion) to do it all myself.

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I did not say that Mechjeb can bring you to the Mun with one click, I just wanted to say that it is damn easy with Pro/Retro orientation and Landing/Ascent autopilots...

On the contrary, the algorythm of Retrograding is so fussy and buggy that it is sometimes much faster to turn retrograde than wait untill it is done automatically.

The 'Mun' button you talk about isn\'t enough a munbutton. I mean, this is just an easy way to calculate the orbit or just put yourself onto that orbit. Of course you had better know what is orbiting about, though.

The guide made by hubbazoot is good enough, I think it\'s just perfect. And, just in case, there\'s one more PDF tutorial made by Guekko, it is now being translated somwhere.

Cheerz,

Shaun.