How The kerbal do I ................

[griffin247]

How The kerbal do I curculise a orbit using Mechjab 2 ? yes i know there is a manover mode for it but when i uses it the countdown passes the motors dont fire and i go slaming into the mun( lucky its only a probe)

[RoboRay]

Thrust retrograde at periapsis or thrust prograde at apoapsis?

[Noticeably FAT]

If you just click 'Go' it only sets up the maneuver node for you, you still have to run the ship. If you want MJ to actually run things you have to click 'Execute node'.

[astropapi1]

Yeah, obviously you slam into the mun.

Check your grammar.

[griffin247]

well ive tried all that, MJ just wont fire up the motors.

[Chocki]

When using Mechjeb to perform maneuvers, keep an eye on your node heading (the blue mark on the nav ball). It tries to align that point before any time warp, and before the burn.

If you have a large ship that rotates slowly, and sas can't keep up to hold that point, it won't be able to realign after time warp before the burn. It likes to keep a node, and be accurate (to the point of trying to adjust an orbit if it is out by 0.2 m/s) If it is not on mark, it tries to rotate, then burn, leaving you way out of postion for planned node. Usually burning late, and then attempting to correct the orbit with weird (but mathematical correct) burns.

Your only choice, besides redesign, is to boost the rotation rates using rcs, to ensure that your heading is on mark for the burn.

Be aware that mechjeb2 loves to deplete rcs fuel. Also, if you have a multi part docked ship (mun lander upside down on top of a travel booster) that you are controling from the ship facing the correct way (such that main motors are point back, like a normal rocket).

Just remember that MJ is trying to fly by math alone. It works well on small quick maneuvering ships, less so on large slow rotaion ships.

[Peenvogel]

As much as I love all the info Mechjeb 2.0 gives me, I have to say it is a terrible autopilot. Thanks to Mechjeb I´ve learned to ascend, land, navigate, plot my courses, dock, do transfers and rendezvous, switch planes and inclination all by hand, probably because my ships were to unstable to be controlled by the autopilot. The RCS is way overpowered and puts most of my ships into spins just by using the most basic maneuvers like TGT+ or REVL-.

However, once you use Mechjeb with a command pod, the control of the autopilot is a lot better! I basically watched what Mechjeb was doing and learned from that to control my own ships.

What you want to do is:

Plot your course to the Mün

Once you're in the SOI, check your posistion

Decide how you want to approach

Change your periapses to the height you want it to be

Change you inclination to what ever you need it to be

Now fly to the newly set periapses and just before you pass it, burn retrograde to circularize

Edited May 3, 2013 by Peenvogel

[griffin247]

wow thanks lads that explains alot i will experiment and report back

[Sovek]

simple, dont rely on MJ2 to fly your ship for you. Execute the burns yourself, and let it handle SASS functions.

What you want to do is:

Plot your course to the Mün

Once you're in the SOI, check your posistion

Decide how you want to approach

Change your periapses to the height you want it to be

Change you inclination to what ever you need it to be

Now fly to the newly set periapses and just before you pass it, burn retrograde to circularize

And this is possibly good, but not quite. Inclination changes outside of the Mun's SOI is tricky, but getting your Pe right outside of the SOI is more efficient. Adjust as needed once you reach Mun's SOI.

Edited May 3, 2013 by Sovek

[Peenvogel]

And this is possibly good, but not quite. Inclination changes outside of the Mun's SOI is tricky, but getting your Pe right outside of the SOI is more efficient. Adjust as needed once you reach Mun's SOI.

But I suggested to change the inclination once you're in the SOI of the Mün.

[magnemoe]

When using Mechjeb to perform maneuvers, keep an eye on your node heading (the blue mark on the nav ball). It tries to align that point before any time warp, and before the burn.

If you have a large ship that rotates slowly, and sas can't keep up to hold that point, it won't be able to realign after time warp before the burn. It likes to keep a node, and be accurate (to the point of trying to adjust an orbit if it is out by 0.2 m/s) If it is not on mark, it tries to rotate, then burn, leaving you way out of postion for planned node. Usually burning late, and then attempting to correct the orbit with weird (but mathematical correct) burns.

Your only choice, besides redesign, is to boost the rotation rates using rcs, to ensure that your heading is on mark for the burn.

Be aware that mechjeb2 loves to deplete rcs fuel. Also, if you have a multi part docked ship (mun lander upside down on top of a travel booster) that you are controling from the ship facing the correct way (such that main motors are point back, like a normal rocket).

Just remember that MJ is trying to fly by math alone. It works well on small quick maneuvering ships, less so on large slow rotaion ships.

Look to me that the best way to do this is to first let mechjeb caculate the node, then do an manual align towards the node and then press execute, for extra safety warp manually do an realign and press execute an minute before node.

For mechjeb it should be an option to set time to rotation and align.

[Sovek]

But I suggested to change the inclination once you're in the SOI of the Mün.

Was referring to the Pe adjustments mainly.

[griffin247]

well something is wrong as i sill cant curilise orbit, even thou am on the blue curcle motors dont fire and to make things worst i cant even stage not even if i shut down the MJ nothing i do will let me fire motors manuly or even stage the probe so can use probes motor

[Sovek]

Wait, Ion engine? If so, there is your problem.

[griffin247]

no it is not a ion motor

[Payload]

nothing i do will let me fire motors manuly or even stage the probe so can use probes motor

I'll bet you have no electrical power. It's not mechjeb that is your problem. I always put at least one RTG on my stuff so this doesn't happen.

I do find it amusing how people blame MechJeb for all their problems. It must be that crazy computer you don't understand right? Not the million other things you don't understand about the game or space flight in general.

[griffin247]

oohh i go away and find the kerbal sparky fella

[Nibb31]

Once you have your Mun transfer node, in Kerbin orbit, adjust it BEFORE doing the burn by pulling back the yellow marker. This will raise the Pe so that

your trajectory doesn't slam into the Mun. You save fuel by doing the Pe adjustment in Kerbin orbit.

erbin

[griffin247]

doah now why dint i think of that .....................you know when you play to long cause you forget the sillyest thing

[Panichio]

Maybe you need to stage, because the engine isn't actually activated yet. Although 'blue curcle motors' really does sound like an ion engine. Alternatively, your whole craft could be without power, in which case nothing will work. Add some solar panels or and RTG, as well as extra batteries if this is the case.

[griffin247]

hey thanks all . the problems have now been sorted. as i said if play long enough and hard enough you tend to forget the simple things anyhowwzzzzzzz thankies again.

[LeathalMeatball]

just do manual retro/prograde burns