Patched Conics Reliability

[gooseapple5]

I keep having problems with patched conics, where after my maneuver it says for instance at Duna I should arrive about 200km off, but when i get about halfway between the transfer (No RCS or accidental engine touches) the patched conic suddenly changes to another number, however once I get to the planet it is a whole other number that isn't even close, in one of my games it got about a million km difference. Is it normal for it to be like this, and is there a way to minimize or hopefully fix this problem? The game version is 1.8.1.

[AHHans]

I think that the patched conics as such are fine, but your orbit changed. I have the impression that when you switch immediately to a high time-warp then the way that the current motion of your ship gets converted to an orbit has at least rounding errors(*) that causes you orbit to change a little bit. And a small change in orbit while escaping Kerbin will translate to a large difference on where you'll arrive around Duna.

I do two thing to minimize this issue: one is to not jump to high time-warp when controlling a ship, i.e. not just click on "jump to next maneuver" or so, but first go to 50x or so manual time-warp and then hit that button. Or to leave the vessel completely, e.g. by going back to the KSC, and doing the time-warp there. The other is that whenever I come out of time-warp with an already set maneuver node I check that node by clocking on prograde/retrograde/whatever without actually dragging - and thus changing - the marker. That will apply the maneuver node to my currently actual orbit, and I can adjust it if needed.

(*) I think they are not typical rounding errors but probably errors with the getting the time-stamp right for the conversion from one reference frame to another.