Hi there, I am using the Launch to rendezvous function in the same way as I did in MechJeb 2.0.7, but its no longer working and often out by a few hundred kilometers. Also It takes me to an orbit of that which is entered in the autopilot box at the top of the ascent guidance window and not to that of the target selected.

The rendezvous autopilot function also hasn't been working in orbit, it will make it to the phasing orbit but not do a retrograde burn to initiate the Hoghmann transfer orbit.

I am using KSP version 0.20 and MechJeb 2.0.8.0

Thanks for all your hard work making MechJeb

The "launch to rendezvous" function is not very well documented. Here is how it is intended to be used:

1. Pick a target.
2. Enter the altitude of the target into "Orbit altitude."
3. Do a normal launch (NOT a "launch to rendezvous"). MechJeb will use this launch to measure the phase angle between launch and entering the desired orbit.
4. Once you get into orbit (probably nowhere near the target), restart the flight.
5. Select the target on the map view.
6. Do a "launch to rendezvous"; the angle text box should be auto-filled with the appropriate angle MechJeb measured during the practice launch.
7. MechJeb will wait until the appropriate time, launch, and hopefully finish the circularization burn within a few kilometers of your target.

The idea is that MechJeb needs a practice launch to learn the correct launch phase angle. Unfortunately the interface gives no hint of this, which is something we need to improve.

The rendezvous autopilot issue sounds separate; could you make a separate bug report for that? If you do it will be helpful to have more information, like: What is your starting orbit? What is your target's orbit? What status is the autopilot displaying when it fails? Is there anything going on in the debug log, which you can bring up with Alt-F2?

Ahh ok thank you for the quick response and explaining that to me. I must have been doing a normal launch first when I was building my ships to test them and this was why it was working for me before the update. After this I suspect the rendezvous function is working fine too and its just something I am doing wrong. I will try and replicate what was happening before and if it pops up I will let you know the details.

Thanks again. Mechjeb is great. It makes the game so much more usable and fun.

There still looks like something is off with ascent module.

I launch from the Mun (not sure if this is a factor).

Quicksave, select the target, set the angle to 0 just in case, do normal launch (not rendezvous). Quickload.

I now have some angle value, do "launch to rendezvous" and I'm off by ~40 degrees on the orbit.

The orbit is 70km, ascent is really steep - immediate start, 10km end, 20% turn. I'm not sure if save and load is supposed to work. The procedure gets me ~50deg angle, the values that by hand get me close to target ship is 2deg. Maybe that's a factor that launch profile is almost like a transfer orbit. I can upload save if you want.

Launching from the Mun complicates things. Currently, if you want to launch to rendezvous from anything except Kerbin, you'll have to mark the time of liftoff manually during your practice launch. To do this, make a new custom info window and add the "MARK" item to it (maybe make an Ascent Stats preset window and add MARK to it). "MARK" is just a button that says "MARK." You'll need to press that button when you lift off from the Mun during your practice launch.

I'll think about how to simplify this whole process for both Kerbin launches and off-Kerbin launches.