Calculation of rotor blade-vortex interaction airloads using a multiple-trailer free-wake Tmodel

Analytical results of rotor blade-vortex interaction airloads are presented with two different wake models in the comprehensive analysis CAMRAD II, and these calculated results are compared with the experimental data obtained from the higher-harmonic-control aeroacoustic rotor test (HART-I) program. The HART rotor was a 40 percent, Mach-scaled model of the hingeless BO-105 main rotor. Two wake models used in the comprehensive analysis are the single-trailer and the multiple-trailer free-wake models. The multipletrailer wake model shows good prediction of lift distribution, M2cn, as a function of azimuth for baseline, minimum noise, and minimum vibration cases, and shows significant improvement relative to the single-trailer model in prediction of the tip vortex wake geometry.