hi karsten,

yes the airfoil is symmetric. I believe you are right that a and b will switch depending on the blade. that isn't something that affects me but if it is messing you up, let me know. I know in the code there are four outcomes that I had to program. clockwise, counter-clockwise, swept forward, and swept back. so you may run into that as well. I don't have moi yet. I was waiting for v4 to come out, to try and make the switch easier. I don't know anything about the node editor or all of max's custom scripts. I have been reading the forum for years though. so I kind of know what all has been going on. but I haven't used any of it. I'm sure i'll have lots of questions once I get started.