Dynamics of the McDonnell Douglas Large Scale Dynamic Rig and Dynamic Calibration of the Rotor Balance

iii NOMENCLATURE C r modal damping, lb-sec/ft C T rotor thrust coefficient H transfer matrix relating the vibratory hub loads to the balance signals; inverse of the dynamic calibration matrixˆH complex representation of H i −1 Im imaginary part of a complex number K r modal stiffness, lb/ft M r modal mass, slug nP n-per-rev or n per rotor revolution Re real part of a complex number s frequency response of shaker excitation, complex scalar, lb u i input vector indicating type of shake, complex constant ˆ u i frequency response of input vector, complex U real representation ofˆUˆU input matrix with column u i , complex v vector of uncorrected five-per-rev balance signal components, real w vector of corrected five-per-rev hub load components, real y i frequency response vector of balance transfer functions, complex ˆ y i frequency response vector of balance channels, complex