In every aeronautical engineering publication I've seen, the convention for "positive" has been: -- Positive aileron deflection creates a positive rolling moment, positive around the +X axis, i.e. roll to the right; -- Positive rudder deflection creates a positive yawing moment, positive around the +Z axis, i.e. yaw to the right; and -- Positive elevator deflection creates a positive pitching moment, positive around the +Y axis, i.e. nose up.
... and likewise for the trim. The conventional orientation of the axes is: http://www.av8n.com/how/htm/motion.html#fig-axes see also http://www.av8n.com/how/htm/motion.html#fig-rotations Now the peculiar thing is that internally, FG uses the opposite convention for the /controls/flight/elevator property ... and likewise for the elevator-trim property. I do *not* propose to change the FG internals. I repeat, we should *not* change the existing internal properties. However, for external purposes, i.e. for gui purposes, I cannot bring myself to expose the backwards elevator convention. I don't see any way to explain that to the users; it doesn't pass the red-face test. As the saying goes, sometimes a few lines of straightforward code is better than a hundred lines of tortured, apologetic documentation. Therefore, for the convenience of gui implementors, I have created the new properties /controls/flight/flipper /controls/flight/flipper-trim following the terminology of Langewiesche. If it's good enough for old Wolfgang, it's good enough for me. These new properties are the same as the corresponding elevator properties, except for a minus sign. If you don't like this new feature, you don't have to use it, and it costs you nothing. http://www.av8n.com/fly/fgfs/flipper.diff The gui that uses this feature will be discussed shortly. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
