MJ launch to rendezvous - does it work?

[kurja]

I tried to use mechjeb's launch to rendezvous and ascent autopilot to send new parts for a ship I'm putting together in 75x75 orbit, but the launches end up ten to fifty kilometers off target; what am I doing wrong? Or does it work any better for anyone else?

[thescientist]

I tried to use mechjeb's launch to rendezvous and ascent autopilot to send new parts for a ship I'm putting together in 75x75 orbit, but the launches end up ten to fifty kilometers off target; what am I doing wrong? Or does it work any better for anyone else?

Remember that even if it is less accurate than a manual launch-to-rendez vous (it's possible to obtain less than a Km of distance with a little practise), this save a lot of time and fuel. 10 Km aren't so bad also for a medium-skilled player.

[kurja]

I guess my expectations were too high, then. I just don't see a lot of difference in ending up ten or fifty kilometers away with mj or doing it by my own guesstimation, if I'm 200 or 20 kilometers away I'll need to adjust my orbit anyway to get closer so it makes no difference. I've had mechjeb launch to rendezvous and ended up over seventy kilometers to target so it's not exactly precise either. Well okay I'll need to wait with timewarp on a few more orbits to catch up the longer distance but that has no implication, no more fuel is used.

[Torminator]

One thing to keep in mind, is LtR needs to know your rocket's launch phase angle. That is, how long does it take to establish orbit. You first do a practice launch, circularize in the orbit you'll want, and then MJ will remember the phase angle. Revert, choose Launch to Rendevous, and that angle will be automatically entered.

[kurja]

I had no idea that MJ had such "learning capability", thanks!

[allmappedout]

With an accurate launch phase angle, Mechjeb can put you within 100m of the target. Good output requires good input

[DChurchill]

It's hit-or-miss. I've hat it put me within a couple kilometers, other times I'm off by 50 like in your example.

[Starwaster]

One thing to keep in mind, is LtR needs to know your rocket's launch phase angle. That is, how long does it take to establish orbit. You first do a practice launch, circularize in the orbit you'll want, and then MJ will remember the phase angle. Revert, choose Launch to Rendevous, and that angle will be automatically entered.

Crap! So I guess it's bad that I keep zero'ing that field out, huh?

[Traches]

You can do it manually too-- Make a custom window that shows you the phase angle to your target, record that angle at launch and when you circularize, and work out the difference so you know precisely when to launch.

[DelayedReaction]

oh yay I've remembered my forum credentials! sorry to resurrect an old post but I have a question regarding launching to rendezvous and while it has been semi-answered in this thread I need a bit more information.

so I set my target, click the launch to rendezvous button, then engage the autopilot and wait for the magic to happen... do I have to set my orbit altitude in MJ as well? the first time I launched to Rendezvous I noticed my orbit was equal to the old data I had in the box from a previous mission.

Or is that just a sheer coincidence because my target's orbit was within 5k of my old orbit?