A METHOD FOR COMPUTING ROTARY WING AIRLOAD DISTRIBUTION IN FORWARD FLIGHT
CORNELL AERONAUTICAL LAB INC BUFFALO NY
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An investigation was made to obtain a solution to the airloads problem for a rotating wing in steady-state translational flight. A sufficient amount of the wake detail was retained to enable accurate computation of the wake-induced velocities at the blade. The method of solution developed is numerical, utilizes high-speed digital computation, and is relatively simple to use. Each blade was represented by a segmented lifting line and the shed and trailing vorticity distributions are represented by a continuous mesh of segmented vortex filaments originating at the instantaneous position of the blade. The wake of each blade of the rotor was different these wakes change with the azimuth position of the blades to correspond to the instantaneous wake configuration for each azimuth position. The method developed was used to compute the rotor airload distributions for the Bell HU-1A, the Sikorsky H-34, and an NASA model rotor in forward flight. The computed airloads were harmonically analyzed and the radial distribution of each harmonic compared with the measured distributions. In general, encouraging agreement is obtained in these comparisons. Effects of changing some of the parameters of the computation were investigated.