An Experimental Investigation of the Stability of a Bearingless Model Rotor in Hover

A 1.79 m diameter model rotor was used to investigate the aeroelastic stability of an isolated bearingless rotor blade in hover, and the results were compared to theory. Configurations tested included: 1) an uncoupled configuration with a leading and trailing edge pitch link; 2) a cantilever pitch arm configuration with a single pitch link on the leading edge of the blade (three pitch link radial locations were studied); 3) a cantilever pitch arm configuration with a single trailing edge pitch link (again three radial locations were studied); 4) a trailing edge pitch link lacation with 2.5 degrees precone; and 5) a trailing edge pitch link location with &minus 2.5 degrees droop. Lead‐lag damping and frequency were heavily dependent on pitch link radial location at higher pitch angles for the cantilever pitch arm configurations studied. Theoretical predictions show stability trends quite well in almost all cases but show discernable differences in damping at higher pitch angles.