Circularization burn minigame

[kinnison]

After ascending and having my apoapsis reach the desired level, I kind of think that the Less i need for a Circularization burn, the better job i did at efficiently ascending. or am i deluding myself?

[Kabloosh]

No, you save fuel in the long run when you do a proper burn. When you are taking off from the mun or any other body without an atmosphere it is best to start turning immediately save to avoid hitting mountains due to this. For atmospheres you might just want to burn straight up but after a certain point a gravity turn is a must.

[Streetwind]

After ascending and having my apoapsis reach the desired level, I kind of think that the Less i need for a Circularization burn, the better job i did at efficiently ascending. or am i deluding myself?

Pretty much, yes.

The most efficient ascent is one where you reach your apoapsis at the same time your apoapsis reaches your desired height AND your periapsis also does so (i.e. you gravity turn directly into a fully circular orbit and don't need any circularization burn at all). In practical application this is so difficult when launching out of an atmosphere that even MechJeb can't do it, because the optimal ascent profile is unique for each individual rocket. And the difference between the optimal ascent and a slightly suboptimal one, where you do a bit of apoapsis surfing while circularizing and your apses are maybe a kilometer or two off from your desired ideal, is really just a few percent.

Honestly, if you can achieve two thirds of your orbital velocity by the time your apoapsis is where you want it and you cut your engines off to coast, you're doing decently. That's about 1500-1600 m/s for Kerbin. If you can do three quarters (1750+), that's excellent and only a small number of people even bother with more accuracy than that.

Edited March 5, 2014 by Streetwind

[problemecium]

I usually shoot for 2000... but then again I'm obsessive. I find around 1800 is enough.

[magnemoe]

I had an refueler I used during the Jool lander mission who ended up with needing less than 200 m/s for circulate, more fun less than 100 m/s with the refueler itself.

Yes I had to launch more than ten of them so I optimized between the launches.

[Ascension Islander]

I've found that with slight adjustments to throttle and pitch, it's not that hard to get a decent apo/per combo without cutting off the engines. The trick is to watch your time to apoapsis. Pitching down past the horizon and backing off the throttle both will decrease it. Try to get it to count down to zero at the same time as your eccentricity reaches zero.

[kinnison]

I usually have no problem getting an orbital velocity of over 2k before I get my apoapsis to 75k. Usually need less then 1k delta to circularize.