ROTOR VIBRATORY HUB AND BLADE LOADS PREDICTION AND CORRELATION

This paper presents results of an ongoing comprehensive vibratory hub and blade loads flight test correlation effort. The study focuses on the capability and consistency of one analytical methodology, COPTER, applied to seven modem four-bladed hingeless and bearingless rotor configurations: prototype models M4BW, M222/ALR, and M222/680, and production models M407, M412, M427, and M430. Baseline correlation is augmented by an investigation of modeling effects to provide some physical insight into the ability of providing a consistent level of correlation across multiple platforms. COPTER’S current methodology results in excellent trim parameter correlation, good blade load consistency, and fair hub load prediction for these aircraft. This level of correlation has been consistently achieved for seven modem rotor configurations using a consistent analytical methodology. Vibratory hub loads are very sensitive to vortex viscous diffusion. Because Drees and time-domain wakes are not sensitive to these effects, vibratory loads correlate better at high speed. Future vibratory hub loads research should continue to include forward flight vortex wake measurements and associated analytical improvements.