How can I return to Kerbin from the Mun using Mechjeb?

[DrunkDave89]

So, with the assistance of mechjeb, I finally managed to get a rocket to munar orbit and onto the surface. Once I got back up to a 5km circular orbit, I found that there was no way to get home save my (incredibly inept) manual piloting skills. Unfortunately, the trans section under orbital operation does not have a way to get me back home that I can see. Am I missing something? I managed to make a blind guess and get myself into an elliptical orbit that intercepted Kerbin, unfortunately I intercepted it at about 700 m/s, and my chutes failed...

What is the best way (using mechjeb) to get from munar orbit to a stable orbit over Kerbin? Im beginning to run out of pilots.

[bsalis]

I don't think MechJeb supports returns. It doesn't do the inclination to get to Minmus either.

Though it seems you made it back to kerbin anyhow. Your chute should not fail if attached correctly and activated before the opening altitude. I have done straight-in re-entries without an orbit and the chute was fine.

It's not that hard to do it well enough manually. I won't go into explaining it because that's not what you asked, and someone else can probably do a better job, or more likelly point to existing material to explain how to do it.

[Legal2k]

My wild suggestion is you have to reach Mun escape velocity, after that you are in Kerbin Soi and orbiting Kerbin, then do retrograde burn at apoapsis (as it uses less fuel) until your orbit is less than 70km.

Edited August 16, 2012 by Legal2k

[maltesh]

I don't think MechJeb supports returns. It doesn't do the inclination to get to Minmus either.

Mechjeb does indeed do an inclination change to get to Minmus, if necessary. Mechjeb does it at a high altitude , when the spacecraft is moving much slower, and thus the fuel cost to change inclination is lower (generally halfway to two-thirds of the way there, in my expeirience, I presume it's actually doing the math for minimal fuel costs.)

After all, you don't have to match Minmus' orbital inclination to reach Minmus, you only have to go through Minmus' orbital plane at the place and time when Minmus is nearby.

If you want to return from the Mun just using Mechjeb, get into orbit, then use its Orbital Operations panel to raise your apoapsis to a point higher than the radius of the Mun's SOI (2200km or so.) That will get you out of the Mun's SOI, and allow you to then land on Kerbin. It's not the most efficient way to return from the Mun, however.

A very efficient way involves burning directly from the Mun's surface (or very low Munar Orbit) into an orbital path that is hyperbolic, and puts you at or near the center of the trailing edge of the SOI moving fast enough to cancel most of the Mun's 545 m/s of velocity. If you're in orbit of Kerbin at 11400km altitude, and moving slower than 176 m/s in any direction, your orbit will intersect Kerbin, as shown in this video.

[togfox]

From the mun, flight straight up till you reach 700m/s then cut engines. Switch to map view and make sure your AP is outside the Mun SOI. Warp forward and you'll be in Kerbin orbit. From there, retroburn till your PE hits 30km altitude

[Kosmo-not]

If you're in an equatorial orbit, wait until the pink marker is at 40° above the horizon and then burn prograde up to around 825 m/s. This is approximately the most efficient you can be.

[DrunkDave89]

Thanks for all the help guys. I'm hoping to get a manually flown flight to the moon done sometime in the next week.

[togfox]

From the mun, flight straight up till you reach 700m/s then cut engines. Switch to map view and make sure your AP is outside the Mun SOI. Warp forward and you'll be in Kerbin orbit. From there, retroburn till your PE hits 30km altitude

I wrote a MECHJEB autom8 script to do exactly this last night. You may not use autom8 of course, but if you do, there is now a script for it.

[DrunkDave89]

^ I do not fully understand what autom8 is. I assume it functions by me downloading a script or somesuch and then typing something into the autom8 box to execute it. Am I anywhere near correct? My understanding of how programming works is at the level where I understand that scripts have nothing to do with theatre, and that's about it, so I'm flying pretty blind here.

That said, I'd be more than glad to give it a try, if you'd kindly post a link.

[Legal2k]

^ I do not fully understand what autom8 is. I assume it functions by me downloading a script or somesuch and then typing something into the autom8 box to execute it. Am I anywhere near correct? My understanding of how programming works is at the level where I understand that scripts have nothing to do with theatre, and that's about it, so I'm flying pretty blind here.

That said, I'd be more than glad to give it a try, if you'd kindly post a link.

IF you look at this thread: http://kerbalspaceprogram.com/forum/showthread.php/16503-MechJeb-Autom8-Scripts-Megathread

you find plenty of info what is Autom8 and how to use it and ready made scripts.

[togfox]

Dave - your summary is correct. Put the right file in the right place then execute a single command. You need not know programming, that's the job of others. Legal has provided a link, that's the best place to ask further questions.

[DrunkDave89]

Cheers for that.