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The influence of disturbances to the flow around a heli-copter resulting from a resultant reaction of the wake fromthe main rotor on the tail rotor, on the loading as well ascontrol and noise of the helicopter was presented. The ana-lysis was based on a rotational model of the system. Thebasis of the model of the interference is the replacement ofwake generated by rotors and fixed lifting surfaces by a uni-form rotational model in the form of discrete rotational grids.This allows for the integration of fields induced through allrotational elements of the system, in accordance with theBiot-Savart law. This law was accepted in view of the factthat, as the only law included in the flow model, it enablesa constant processing of load calculations in an undefinedflight, with the retention of a reasonable calculation time.The undertaking of this subject should help explain pheno-mena not completely recognized and which exert a signifi-cant influence on safety when operating helicopters certainstates of flight. The results of modeling, carried out for theSW4 helicopter, contain an evaluation of disturbances of thefield of flow around the tail rotor in given states of flight, inwhich the case of take-off in a sidewind and with the car-rying out of a directional maneuver is of primary signifi-cance. In other cases, when the tail rotor does not enter intointensive disturbances of the velocity field by the main rotor,the interference phenomena are of lesser importance. Thenumerical program used allows for information about flowaround and loads on the tail rotor in flow disturbed by the(main) rotor to be obtained. Resultant loads on the tail rotorcan be evaluated, along with its chosen elements.
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