Evaluation of Rotorwash Characteristics for Tiltrotor and Tiltwing Aircraft in Hovering Flight
SYSTEMS CONTROL TECHNOLOGY INC ARLINGTON VA
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The rotorwash characteristics of eleven different types of tiltrotor and tiltwing aircraft in hovering flight are presented for comparison purposes. Rotorwash characteristics that have been quantified included the mean and peak outwash velocity profiles off the left wing position azimuth 270 degrees and nose position azimuth 0 degrees. Maximum values from each of the peak velocity and peak dynamic pressure profiles are also presented as a function of distance from the rotorcraft along both the 0 and 270 degree azimuths. Calculated personnel overturning forces are presented along both azimuths for a six foot tall person. All documented results were calculated with the ROTWASH analysis program. Flight test data, as correlated with the analysis program, are presented for the XV-15 tiltrotor and the CL-84 tiltwing. These hover characteristics do not represent the worst case scenario characteristics which would be expected at a vertiport. Scenarios involving ambient winds and maneuvering flight near hover generate higher rotorwash velocities. Unfortunately, the identification and prediction of worst case scenario results for comparison purposes is not presently possible. A companion report, entitled Rotorwash Computer Model - Users Guide, DOTFAARD-9025, discusses the ROTWASH analysis program. This computer program is used to predict rotorwash characteristics of helicopter, tiltrotor, and tiltwing aircraft. The program also has the capability to analyze several different types of rotorwash related hazards which might be encountered in a vertiport environment.