Circularization Troubles

[Joeybafoey]

I'm a recovering Mechjeb addict and am currently learning to fly my rockets all by myself (basically, I'm learning to play the game again). I have no problem with flying onto a suborbital trajectory, but when I go to create my circularization burn, I can't seem to get a near-perfect orbit, and am clueless when it comes to exexuting precise maneuver nodes. Does anyone have any trips?

[Theysen]

Click near the apoapsis and drag until the orbit becomes roughly circular. This gives you a good estimation of burn time. Start your burn according to the given maneuver node value and watch your vertical speed. Once it reaches 0 you start falling back to Kerbin. Pitch up to counter to this movement and "ride the apoapsis" until the camera flickers. Doing so you don't change your desired apoapsis as you maintain ~ 0 m/s vertical speed at the highest point of the trajectory. As you might play with KER or MechJeb for telemetry output you can burn until your periapsis will be at the same altitude as the apoapsis. You're guaranteed to be in a near circular orbit. All you have to do is to keep your vertical speed at around 0 once you reached apoaopsis. Beware though, this is quite the fine handling in stock system size. You can also throttle down towards the end of the burn so you get much more fine control over things.

[DChurchill]

Do circularization burns at apoapsis or periapsis. While not absolutley nesessary. you only have to fiddle with the prograde and retrograde handles to get a circular orbit. The arms are pretty fiddly, unfortunately.

[DD_bwest]

if you wanna get your node right at the ap or pe,  create a node near to it, press tab to focus view on it and zoom in as much as you can, and slowly drag it towards the point you want.  radial in/out can also help adjust if you want to at a height thats not your ap/pe

Im also a recovering Mechjeb user, started playing without it to prepare for ps4.  once you get a hang of things it comes pretty quick.  Im still working on getting better at inter planetary burns,  im no where near as efficient as mechjeb lol

[DaMachinator]

This is an interesting question because I am writing a kOS script to make perfectly circular orbits for communications satellites.

[Hans Dorn]

I had some success with watching the time until periapsis apoapsis and lowering thrust when it moves away into the future. Requires some fiddling, and takes a while to complete.

Edited June 7, 2016 by Hans Dorn

[regex]

I generally don't bother with perfect orbits.  During launch I burn at AP once out of atmosphere to raise PE to orbit and then, if it's not already circular and I want to circularize, I burn PE higher than AP.  When I next come around to AP I squirt the engine to raise PE up to about AP and call it good.  Good orbits require tuning.

[Fearless Son]

Once you have raised your suborbital apex to near where you want your orbit to be, make sure your rocket is pointing parallel to the surface (on the horizon line on the navball) and thrust that direction.  The closer you are to your apex when you do this, the less further out your apex will be pushed, so start it well before it raises to the point you want it to be.  Once it does get to the point you want it to be, take the advice others have said here and drop a maneuver node on the apex and extend a prograde thrust until the resulting predicted orbit is near-circular.  Then just burn it like any other maneuver.  If you have a good thrust-to-weight ratio, you might consider doing a lower-throttle burn nearer to the apex to get yourself better control and fuel-efficiency.  A lower thrust-to-weight ratio will require a longer burn starting earlier lest you fall back into a suborbital flight.  

Do not bother with a perfectly circular orbit, those are almost impossible to achieve without automatic guidance.  Just stick with an approximately circular orbit.  

[LordFerret]

I usually just shoot for 'close to circular', then when passing the Ap/Pe nodes (while watching in map mode), a few short bursts of RCS can fine tune and get real close.

[Rocket In My Pocket]

As you make your burn to circularize you want to keep your Ap marker just ahead of your ship; 5-10 seconds ahead of your craft is usually where I like to be. (You can see time to Ap in stock by mousing over the Ap marker in map mode.) Imagine that you are "pushing" it along.

Take care not to pass your Ap marker, if you do nose up gently until it catches up to you then level out and continue as normal. As your Pe rises to match your Ap towards the end of your burn you'll notice the time to Ap rising quickly, you'll want to nose down to counteract this. If you stay just behind it in this manner you should end up with a very nice circular orbit.

That's how I do it anyways. Best of luck!

Edited June 7, 2016 by Rocket In My Pocket

[blorgon]

13 hours ago, DaMachinator said:

This is an interesting question because I am writing a kOS script to make perfectly circular orbits for communications satellites.

Would love to hear about your approach, out of curiosity. I recently finished a script that gives amazingly consistent results across all sorts of crafts.

[Nathair]

21 hours ago, Joeybafoey said:

I can't seem to get a near-perfect orbit, and am clueless when it comes to exexuting precise maneuver nodes. Does anyone have any trips?

It's funny that you should mention precise maneuver nodes...