I am not plagarising anyone - since unlike you I understood this before - I think I said something in a very early post on this thread along the lines of "Crab's misunderstanding most likely comes from his confusion about which reference axis (or plane) he is using - but that's another story" - I prompted you to start reading the text books - NO you are wrong about LEISHMAN he DOES STATE IT very CLEARLY at the ref I gave - the only reason to mention these publications and authors is to show that it's not just me who understands the helicopter in this way - since you wrongly charged me with that. I hope you can honorably say that as a result you now understand something fundamental to helicopters which you previously had not. You can call the Hub Axis the "Shaft Axis" if it makes you feel better - but it's no more correct than the "Drive Axis" "Input Axis" "Head Axis" etc and it doesn't matter too much if you want to refer to the Plane either - call it the 'driving plane' and 'driven plane' if you like. One thing is quite clear - you did not understand it before and you almost do now - admit it (for once)