Mun Orbit?

[Buckeye1]

I've been working through the tutorials for ksp on ps4. I'm trying to get into Mun orbit. I understand the mechanics of maneuvers and I can get fairly close to the Mun. The tutorial wants me to have a relatively circular orbit under 200,000. My closest periapsis has been ~132,000 while my apoapsis has been ~240,000. My eccentricity has been 0.2. However, I run out of fuel to get any closer because the tutorial has me creating all these maneuvers and burning retrograde at least three times. Any suggestions. (Sometimes I get estimated burns to be 3-10 seconds. Is this a glitch or should I just roll with it?)

Edited July 29, 2016 by Buckeye1

[dafidge9898]

19 minutes ago, Buckeye1 said:

I've been working through the tutorials for ksp on ps4. I'm trying to get into Mun orbit. I understand the mechanics of maneuvers and I can get fairly close to the Mun. The tutorial wants me to have a relatively circular orbit under 200,000. My closest periapsis has been ~132,000 while my apoapsis has been ~240,000. My eccentricity has been 0.2. However, I run out of fuel to get any closer because the tutorial has me creating all these maneuvers and burning retrograde at least three times. It wants me to have a relatively circular orbit under 200,000. Any suggestions. (Sometimes I get estimated burns to be 3-10 seconds. Is this a glitch or should I just roll with it?)

Estimated burn time never really was accurate. At least for me. When you make your intercept with the Mun, make sure your periapsis is at 200 km. Make sure it reads 200 km before you even get into the Mun's SOI. Then you circularize at periapsis of the Mun for a 200km circular orbit. This uses less fuel. If you can't get the intercept right on 200km, then correct before you reach the Mun. 

[Buckeye1]

1 minute ago, dafidge9898 said:

Estimated burn time never really was accurate. At least for me. When you make your intercept with the Mun, make sure your periapsis is at 200 km. Make sure it reads 200 km before you even get into the Mun's SOI. Then you circularize at periapsis of the Mun for a 200km circular orbit. This uses less fuel. If you can't get the intercept right on 200km, then correct before you reach the Mun. 

To circularize the orbit, should I use a retrograde burn or an anti-normal/normal maneuver?

[dafidge9898]

18 minutes ago, Buckeye1 said:

To circularize the orbit, should I use a retrograde burn or an anti-normal/normal maneuver?

Retrograde. If you're circularizing at periapsis (which in this case, an intercept, you are), you always circularize burning retrograde. If you're circularizing at apoapsis, then you burn prograde. 

[bewing]

Retrograde at your Pe is always the most efficient, because of the Oberth effect. And as dafidge9898 said, adjusting your Munar Pe just as you are leaving Kerbin is also the most efficent for fuel. (Click on the Mun, and say "Focus view" -- and it will show you your Munar flyby trajectory in realtime as you burn.) Anything from a 20km to 200km Pe is good.

You use Radial-In and Radial-Out burns to fine tune the circularity of the orbit after you've done most of the burn at the Pe.