Anti-torque device with shrouded rotor and phase modulation of the rotor blades positions for helicopters

摘要

The tail rotor consists of a multi-bladed variable-pitch rotor (7), mounted coaxially inside an air flow channel (6) surrounded by a housing (5) containing a flow rectifier (8). The rotor blades (10) move perpendicular to the axis of the channel (6) and have an angular distribution round the rotor's axis with an irregular azimuthal modulation determined from a formula based on the number of blades. The azimuthal modulation of the rotor blades corresponds basically to a degraded sinusoidal law, according to which the angular position of one blade varies by a maximum of +/- degrees relative to a fixed angular position. The air flow rectifier is in the form of a stator with fixed blades (9) positioned so that they straighten out the air flow from the rotor, forming a flow parallel to the rotor's axis. IMAGE