I thought that I had build a Lancair IVP turbine, but after seeing all of the post, it must be something else.

 

  My IVP has no yaw damper, and no winglets.  It is very stable in yaw in all regimes of flight.  One does need to trim the rudder with speed and power changes.  My rudder trim in on the stick for this reason as is the aileron and elevator.

  By the way, I also found the 727 to have no yaw problem with the dampers off except at high altitude, the operating manual noted this very strongly.  I only flew the 727 for 18,000 hours in all three seats, so I am not really an expert. 

 

Jim Hankins