Influence of unsteady aerodynamics on hingeless rotor ground resonance

Calculations of the model frequency and damping for a hingeless rotor on a gimballed support in hover are compared with measured results for two configurations (differing in blade flap stiffness). Good correlation is obtaned when an inflow dynamics model is used to account for the influence of the unsteady aerodynamics. The effect of the unsteady aerodynamics is significant for this rotor system. The inflow dynamics model introduces additional states corresponding to perturbations of the wake-induced velocity at the rotor disk. The calculations confirm the experimental observation that the inflow mode introduced by these additional states is measurable for one configuration but not for the other.

[1]  David A. Peters,et al.  Theoretical Flap-Lag Damping With Various Dynamic Inflow Models , 1980 .

[2]  Wayne Johnson,et al.  A Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics. Part 1. Analysis Development , 1980 .

[3]  Edward Seckel,et al.  Characteristic Lateral-Directional Transients , 1964 .

[4]  David A. Peters,et al.  Use of Multiblade Coordinates for Helicopter Flap-Lag Stability with Dynamic Inflow , 1980 .

[5]  R. Loewy.  A Two-Dimensional Approximation to the Unsteady Aerodynamics of Rotary Wings , 1957 .

[6]  David A. Peters,et al.  Hingeless Helicopter Rotor Response with Nonuniform Inflow and Elastic Blade Bending , 1972 .

[7]  William G. Bousman,et al.  An Experimental Investigation of the Effects of Aeroelastic Couplings on Aeromechanical Stability of a Hingeless Rotor Helicopter , 1981 .

[8]  D. Banerjee,et al.  Parameter identification applied to analytic hingeless rotor modeling , 1979 .

[9]  D. Peters.  Hingeless rotor frequency response with unsteady inflow , 1974 .

[10]  David A. Peters,et al.  Theoretical prediction of dynamic inflow derivatives , 1980 .

[11]  Edward Seckel,et al.  Stability and Control of Airplanes and Helicopters , 1964 .

[12]  Kurt H. Hohenemser,et al.  Identification of state variables and dynamic inflow from rotor model dynamic tests , 1977 .

[13]  R. H. Miller,et al.  Rotor blade harmonic air loading , 1964 .

[14]  Paul J Carpenter,et al.  Effect of a Rapid Blade-Pitch Increase on the Thrust and Induced-Velocity Response of a Full-Scale Helicopter Rotor , 1953 .