DERIVATION OF ROTOR BLADE GENERALIZED AIR LOADS FROM MEASURED FLAPWISE BENDING MOMENT AND MEASURED PRESSURE DISTRIBUTIONS
Final rept., Jun 1964-Sep 1965
CORNELL AERONAUTICAL LAB INC BUFFALO NY
Pagination or Media Count:
A limited study of methods of deducing generalized air loads acting on a helicopter rotor blade or a propeller blade from bending-moment measurements is presented. A new set of basic functions called orthonormal- moment distributions is proposed as the best set for fitting the moment data. The blade-tip deflections computed from pressure distributions measured on an H- 34 helicopter rotor in steady level flight at 112 knots are compared with tip deflections derived by four methods based on use of measured bending-moment distributions. The degree of agreement between quantities obtained from the pressure distributions and those obtained from the moment distributions is encouraging but not satisfactory. Neither the lift nor the moment distributions were measured with sufficient accuracy for the purposes of the study. Deficiencies in the accuracy of the measurements and in the accuracy of the description of the blade mass and elastic characteristics obscure any meaningful differences between the various methods of operating on the moment data.