NACA-RPT-1351, NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS REPORT 1351: THEORY OF SELF-EXCITED MECHANICAL OSCILLATIONS OF HELICOPTER ROTORS WITH HINGED BLADES (R.P COLEMAN, A.M. FEINGOLD) (NOV-1958)

NACA-RPT-1351, NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS REPORT 1351: THEORY OF SELF-EXCITED MECHANICAL OSCILLATIONS OF HELICOPTER ROTORS WITH HINGED BLADES (R.P COLEMAN, A.M. FEINGOLD) (NOV-1958)., Vibrations of rotary-wing aircraft may derive their energy from the rotation of the rotor rather than from the air forces. A theoretical analysis of these vibrations is described and methods for its application are explained in Chapter one. Chapter two reports the results of an investigation of the mechanical stability of a rotor having two vertically hinged blades mounted upon symmetrical supports, that is, of equal stiffness and mass in all horizontal directions. Chapter three presents the theory of ground vibrations of a two-blade helicopter rotor on anisotropic flexible supports.