CORRELATION STUDIES FOR HINGELESS ROTORS IN FORWARD FLIGHT USING 2GCHAS

The results from the Second Generation Comprehensive Analysis System ( 2GCHAS) are correlated with those from two aeroelastic codes independe ntly developed at UCLA is presented. These results comprise rotating f requencies, trim variables, aeroelastic stability and response of the rotor blade in forward night. The two models developed at UCLA have co nsiderable differences in both modeling assumptions and the method of solution. The first model was developed for isotropic blades undergoin g moderate deflections. The second model was developed for swept tip c omposite rotor blades and accounts for moderate deflections, shear, wa rping, and general blade cross sectional properties. In the second mod el the axial degree of freedom is retained, while it is eliminated in the first model. The formulation and spatial discretization in the two models are fundamentally different as well. Despite these differences very good correlations for trim and aeroelastic response are obtained . Overall, the stability correlations are also good, except for consid erable difference in the torsional damping predicted by 2GCHAS and the other two analyses.