Messing up my manoeuvres

[Zeb Kerman]

I've been playing KSP for almost two months now, and all my kernels are either in the astronaut complex or solar orbit (see my other post). I can't get something into a circular orbit (when I actually get them into  an orbit) I have concluded that it is because I don't know when to burn. Any tips?

[Gargamel]

Well, we have quite a few very good tutorials on reaching orbit, along with a number of good videos that can be found elsewhere. 

But basically, you launch with a gravity turn.   Each vessel will fly a bit differently, but the principle is the same.   You launch, and very shortly there after when the velocity of the vessel will allow for reasonable control (like 50 m/s), you tip eastward (90 degrees on the navball) about 5-10 degrees.    Let the SAS hold it there until the prograde marker catches it, and then switch the SAS to Prograde.  The craft will slowly tip over as it goes up.  This sends you upwards in altitude, but is also bringing you closer to your final path in orbit. 

As you are going up, keep on an eye on the map view, it will show you your Apoapsis.  It should be getting higher at a decent rate.  Too fast and you're not turning over enough, and will need to burn more than necessary later; too slow, your turn is too much, and you'll spend too much fuel fighting atmospheric drag.  With practice you'll get the feel for what this needs to be.   When your Ap gets outside the atmosphere (70km, I like to get mine to 80-100km so I have some wiggle room), cut your engines.   You will now coast up to the Ap before you start falling back down to Kerbin.   

You now have two options.   You can set a maneuver node at the Ap, firing enough in the prograde to bring your Periapsis (Pe) up to match your Ap.  Keep your ship in the prograde attitude until you get near or out of the atmosphere.  This will reduce your drag for as long as possible, and will keep the Ap as high as possible, as drag will cause it drop as you coast.  Once you break atmo, point the ship towards the node on the navball, and when the burn indicator says to, complete your burn.  If all goes well, you should be in a pretty circular orbit.  

Or, alternatively, you can just eyeball it.   This takes a little more practice, but works just as well for the most part.   When your ship is about to reach Ap, point prograde, and burn until your Pe is equal to your Ap.  The practice part is knowing when to start and end the burn. 

That's how I fly my ships, but I'm a notoriously bad pilot.  Other's will come along and give better tips, but this method works for me. 

[Xd the great]

6 hours ago, Zeb Kerman said:

I've been playing KSP for almost two months now, and all my kernels are either in the astronaut complex or solar orbit (see my other post). I can't get something into a circular orbit (when I actually get them into  an orbit) I have concluded that it is because I don't know when to burn. Any tips?

Mods like mechjeb can help you launch properly.

Sometimes watch and learn is a good method.

[Kryxal]

Also, the other reason for a gravity turn (because in old versions, people were fine with going up to 10 km and making a sharp turn) is that now it's very hard to MAKE that sharp turn unless you go a lot higher, and there's less need for it (the lower atmosphere isn't as "soupy").  Now, depending on your rocket design, it's going to be either near-impossible to get more than a few degrees off prograde or really dangerous to try, and either way it raises drag.  Above maybe 25-30 km you can DO it, but try to avoid it unless you're coming up a bit short on your launch.

[Vanamonde]

I haven't updated my guide for quite a while, but it might still be helpful. 

Also, a perfectly circular orbit has few advantages other than aesthetic tidiness. Real spacecraft seldom bother to match periapsis and apoapsis precisely.