[Mod] MechJeb Rendezvous Issues

[GreatWyrmGold]

There being no "Modded KSP Questions" subforum, I figured I'd go here.

I have done many things in my time as a KSP player. I've sent a rocket to Eve. I've sent a helicopter to Eve and realized that an ion engine plus the propeller wouldn't get my kerbal back into orbit. I've sent more missions to Minmus than I can count, built spaceplanes, explored the poles, and tried to figure out Interstellar. But one thing I have not been able to do for the life of me is rendezvous (unless the other object has a sphere of influence).

I decided to try out MechJeb's rendezvous autopilot, but determined that it simply did not work. "Auto-Warp" was a complete bust, unless "auto" here means "only allow 1x". Moreover, it was creating maneuver nodes but then not executing them, which I'm pretty sure is the bare minimum you'd expect an "autopilot" to do. I'm not sure what was going on, but I'm willing to bet that I screwed up something rather than MechJeb is inherently screwed up.

Now, if it was just "MechJeb isn't very good at this; I should see if I can get better at it," I'd just work at my own rendezvous skills. But when I have such a profound failure, I just can't help but wonder what the heck is going on.

[Taki117]

Mechjeb's Rendezvous Autopilot isn't the best thing in the world. Generally speaking, you can do one of two things to rendezvous.

1) Get into a lower orbit and catch up with your target

2) Get into a higher orbit and let your target catch up with you.

Although, I find that instead of using Mechjebs Rendezvous autopilot, it is far easier to go "Hohmann Transfer to target" Then "Fine tune Closest Approach 200m" then "Match velocites at closest approach" if you want to go full Mechjeb.

[Pecan]

There being no "Modded KSP Questions" subforum...

There is a MechJeb thread though: http://forum.kerbalspaceprogram.com/threads/12384-PART-0-24-2-Anatid-Robotics-MuMech-MechJeb-Autopilot-v2-3-1

[FleshJeb]

The Rendezvous window only sets up the nodes for you. You still have to Execute them through the Maneuver Planner. The auto warp only kicks in after the ship has rotated to the node.

[juanml82]

I find the best way to use MJ is to use the RV planner instead of the autopilot.

Be at a different altitude than your target. No idea how much of a difference is optimal. I usually work with whatever orbit I'm starting, specially if it's outside Kerbin's SOI

Match planes

Play with the nodes to get an intercept or let MJ plan it for you and execute it. You can fine tune it with RCS and the H/N keys instead of chasing the marker.

You can then create a "match velocities" node. There are tutorials about how to do it manually if you wish. IIRC, you need to set your navball to target mode and burn towards the yellow retrograde marker until the speed relative to target (which is what the navball will show) is close to zero.

Now, with the navball still in target mode, point at the purple prograde marker (the one with the circle) and burn until your closest approach to the target is either below 100 m or doesn't decrease too much. You might want to create a custom MJ window with distance and time to closest approach. KER probably displays that as well, but I don't use it in RV mode.

Match velocities again. If you aren't close enough, burn towards the purple marker again.

[Zylark]

If jumping from planet to planet, from a moon to another moon or going from a planet to a moon, Mechjeb is pretty much useless. You're better off setting up the maneuver node manually and just use the Maneuver Node Editor of MJ to fine tune it.

Rendezvous Autopilot can be a time-saver *if* you and your target is in more or less the same orbit. If your orbit differs by say 100km or more you're probably better off using good'ol Hohmann Transfer.

Edited September 3, 2014 by Zylark

[Daveroski]

Mechjeb has a variable to restrict the number of orbits it can do before going for the intercept. This is changeable on the autopilot window. I use 5. MJ usually goes for it within 3.

If my target is at 100 km I start my autopilot at 250km.

On starting, MJ warps (with warp on) to the AN or DN to match planes.

Then gets into position for transfer.

Transfers

Matches speed with target.

Intercepts at closest approach.

Moves close to designated distance from target. I usually use 50m on smaller vessels without incident.

[KandoKris]

Mechjeb also dosn't like the new nasa parts and wont fire the rockets till T-minus 0sec instead of buring perfectly this tends to make Rendezvous harder as it keeps missing the mark and starting again.

Honestly I was once the same as you but it is easy.

I no longer even make node for LKO just eyeball.

Easiest way is if your taret is say 100km orbit you go to 200km orbit and then when the target has almost cought-up ( approx 30ish degrees ) reduce your alt to meet(100), make sure your meeting within 30 km so the nave ball does an auto change to "target" from "orbit" speed mark the meeting point with a node just to help with time-warping (move the node back and forth till you have a good intersect)

Once the nav ball changes turn to the crossed circle and burn till your speed is 0 to target or close to it. Now point to your taget (purple circle) now under 30km away and visible as a yellow circle

Burn again. In LKO 20m/s is more then enough.

If your yellow circle move away from the purple one you have drifted. To fix that just burn to the oppersite side of the drift till the yellow and purple match again and repeat if you need to and try to keep that speed to target around the 20 mark then point to the purple cross and wait tll you reach the closest point, before you ram your taget, burn till speed to target = 0m/s depending on how far away you still are you may need to repeat till your under 150m then switch to docking mode (delete key ) turn on RCS and have fun docking.

Its that easy ---- Remember Practice makes perfect and Mechjeb Stops you learning

[John FX]

I find it works fine although I don`t use the autopilot unless I am doing something else and I come back to the game later to find the craft sort of near the target and do a few maneuvers to get it docked. I use the `match planes with target` then as long as I am in an orbit 20km different from the target I just do a hohmann transfer and set an alarm. It uses the least fuel and I can get on with other stuff in the mean time.

[TonesTheGeek]

I am still Forced to manually initiate burns when using the Rendezvous autopilot. Is this mod even being updates and are the developers of it even aware of the problem and doing anything to fix it? I was really enjoying this convenient tool that allowed me to fucus more on designing the spacecraft rather than flying them.

[James Kerman]

Welcome to the forum @TonesTheGeek,

As this is a very old thread it may be better to ask here:

 

[TonesTheGeek]

1 minute ago, James Kerman said:

Welcome to the forum @TonesTheGeek,

As this is a very old thread it may be better to ask here:

 

Thank you, I actually just found that one and asked the same question.

[Vanamonde]

As the info in this thread pertains to outmoded versions of the mod, why don't we go ahead and close it.